Cited by 201Cardiac Ischemia and ReperfusionMitochondrial Function and PathologyCoenzyme Q10 studies and effects

Differential effects of complex II on mitochondrial ROS production and their relation to cardioprotective pre- and postconditioning

Open access
Dröse, Stefan·2013·Biochimica et Biophysica Acta (BBA) - Bioenergetics

Abstract

The production of reactive oxygen species by the mitochondrial complex II (succinate:ubiquinone oxidoreductase) recently has gained broad scientific interest. Depending on the (patho)physiological situation, ROS produced or triggered by complex II can have either beneficial or deleterious effects. This ambivalence can be explained mechanistically by the diverse role of complex II on mitochondrial ROS production: it can be a source as well as a suppressor or enhancer of ROS generation by other respiratory chain complexes. Since complex II directly links the respiratory chain to the tricarboxylic acid (TCA) cycle, the TCA-cycle intermediates - especially oxaloacetate that acts as a high affinity endogenous inhibitor - have major impact on complex II-related ROS release. The review relates the diverse effects of complex II activity on the mitochondrial ROS production that have been observed during cardioprotective ischemic or pharmacological preconditioning and the oxidative burst that occurs during ischemia/reperfusion. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.

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Registry

Crossref · 10.1016/j.bbabio.2013.01.004

Cites

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Claims the paper makes

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  • Findingcitation

    A 5% drop in the mitochondrial membrane potential reduces hydrogen peroxide release from isolated mitochondria by 95%.

    “that a drop in ΔΨ by only 5% reduces the hydrogen peroxide release of isolated mitochondria by 95%.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [18] 18. T.V. Votyakova, I.J. Reynolds, ΔΨ-dependent and -independent production of re- active oxygen species by rat brain mitochondria, J. Neurochem. 79 (2001) 266-277. source

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  • Findingcitation

    Experimental evidence for oxaloacetate-dependent inhibition of complex II under anoxic conditions is lacking.

    “However, experimental evidence for an oxaloacetate-dependent inhibition of complex II under anoxic conditions is lacking [109].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [109] 109. E. Maklashina, A.B. Kotlyar, J.S. Karliner, G. Cecchini, Effect of oxygen on activa- tion state of complex I and lack of oxaloacetate inhibition of complex II in Langendorff perfused rat heart, FEBS Lett. 556 (2004) 64-68. source

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  • Findingcitation

    In isolated rat heart mitochondria, succinate-driven superoxide production at complex I by RET can be abolished completely by 10 nM atpenin A5, a concentration that only partially inhibited succinate-dependent respiration.

    “We could show in investigations with isolated rat heart mitochondria, that the succinate-driven superoxide production at complex I by RET can be abolished completely by atpenin A5 concentrations of 10 nM, a concentration that only partially inhibited succinate-dependent respiration [16].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [16] 16. S. Dröse, L. Bleier, U. Brandt, A common mechanism links differently acting com- plex II inhibitors to cardioprotection: modulation of mitochondrial reactive ox- ygen species production, Mol. Pharmacol. 79 (2011) 814-822. source

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  • Findingcitation

    A physiological correlate of experimentally induced antimycin A inhibition has not been identified.

    “However, it has to be pointed out that a physiological correlate of the experimentally induced antimycin A inhibition has not been identified yet [25].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [25] 25. L. Bleier, S. Dröse, Superoxide generation by complex III: from mechanistic rationales to functional consequences, Biochim. Biophys, Acta (2013), http://dx.doi.org/10. 1016/j.bbabio.2012.12.002. source

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  • Premisecitation

    Complex II activity can strongly influence ROS production by complexes I and III.

    “Furthermore, it is well known that complex II activity can have major impact on the ROS production by complexes I and III [15,16].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [15] 15. S. Dröse, P.J. Hanley, U. Brandt, Ambivalent effects of diazoxide on mitochondrial ROS production at respiratory chain complexes I and III, Biochim. Biophys. Acta 1790 (2009) 558-565. source

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    • cites [16] 16. S. Dröse, L. Bleier, U. Brandt, A common mechanism links differently acting com- plex II inhibitors to cardioprotection: modulation of mitochondrial reactive ox- ygen species production, Mol. Pharmacol. 79 (2011) 814-822. source

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  • May combine two claims. 45
  • Classified as probably not a substantial claim. 33
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    Findingown data

    The modulation of mitochondrial ROS production by atpenin A5 was independent of K+ ions, indicating that a putative mitoKATP channel was not involved.

    “Importantly, the modulation of mitochondrial ROS production was independent of K + -ions, indicating that a putative mitoK ATP channel was not involved.”
    Quote in the paperSubstantial claim
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    Findingcitation

    Similar atpenin A5 concentrations stimulated superoxide production at the Qo site of antimycin A-inhibited complex III, which may represent the source of signaling ROS during ischemic and pharmacological preconditioning.

    “In addition, similar atpenin A5 concentrations stimulated the superoxide production at the Q o site of antimycin A inhibited complex III, which may represent the source of 'signaling ROS' during ischemic and pharmacological preconditioning [15].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [15] 15. S. Dröse, P.J. Hanley, U. Brandt, Ambivalent effects of diazoxide on mitochondrial ROS production at respiratory chain complexes I and III, Biochim. Biophys. Acta 1790 (2009) 558-565. source

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  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Some complex II subunit mutations linked to cancer or neurodegeneration can increase ROS generation.

    “However, some mutations in complex II subunits that have been linked to specific forms of cancer or neurodegeneration can lead to an increased ROS generation (reviewed in [12][13][14]).”
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    • cites [12][13][14]

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The respiratory chain supplies most ATP in eukaryotic cells and is also a major source of reactive oxygen species.

    “The respiratory chain provides the main portion of ATP in eukaryotic cells, but is also a major source of reactive oxygen species (ROS) [2][3][4][5][6].”
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    • cites [2][3][4][5][6]

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    Premisecitation

    Complex II oxidizes succinate to fumarate and reduces ubiquinone, thereby directly connecting the TCA cycle to the respiratory chain.

    “Mitochondrial complex II (succinate:ubiquinone oxidoreductase; succinate dehydrogenase, SDH) oxidizes succinate to fumarate and reduces ubiquinone, thereby creating a direct link between the tricarboxylic acid (TCA) cycle (also known as citric acid or Krebs cycle) and the respiratory chain [1] (Fig. 1).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [1] 1. G. Cecchini, Function and structure of complex II of the respiratory chain, Annu. Rev. Biochem. 72 (2003) 77-109. source

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  • Classified as probably not a substantial claim.

    Premisecitation

    Complexes I and III are generally viewed as the main ROS sources in the respiratory chain, while intact complex II is thought to contribute negligibly.

    “Within the respiratory chain, complexes I (NADH:ubiquinone oxidoreductase) and III (ubiquinol:cytochrome c oxidoreductase; cytochrome bc 1 complex) are generally regarded as the main ROS sources, while the contribution of intact complex II seems to be negligible [3][4][5][6].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [3][4][5][6]

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Mutations in complex II subunits C and D near the Qp site are associated with hereditary paragangliomas and pheochromocytomas, and SdhA mutations can cause Leigh syndrome.

    “This seems to be especially the case for mutations in complex II subunits C and D located in the vicinity of the Qp site that have been associated with specific forms of cancer such as hereditary paragangliomas and pheochromocytomas (overview in [13,14,36]) and in SdhA that can cause Leigh syndrome, a progressive neurodegenerative disease [14,94].”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [13] 13. C. Bardella, P.J. Pollard, I. Tomlinson, SDH mutations in cancer, Biochim. Biophys. Acta 1807 (2011) 1432-1443. source

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    • cites [14] 14. T.M. Iverson, E. Maklashina, G. Cecchini, Structural basis for malfunction in com- plex II, J. Biol. Chem. 287 (2012) 35430-35438. source

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    • cites [36] 36. S.J. Ralph, R. Moreno-Sanchez, J. Neuzil, S. Rodriguez-Enriquez, Inhibitors of suc- cinate: quinone reductase/complex II regulate production of mitochondrial re- active oxygen species and protect normal cells from ischemic damage but induce specific cancer cell death, Pharm. Res. 28 (2011) 2695-2730. source

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    • cites [94] 94. B.A. Ackrell, Cytopathies involving mitochondrial complex II, Mol. Aspects Med. 23 (2002) 369-384. source

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationcitation

    The increased succinate pool under hypoxia may come from glutamate via alpha-ketoglutarate by transamination or from partial reversal of the TCA cycle from malate through fumarate, which would require complex II to act as a fumarate reductase.

    “This increased succinate pool under hypoxia might be supplied either from glutamate through α-ketoglutarate by transamination [76,77] or by a partial reversal of the TCA cycle from malate through fumarate, which requires that complex II would become a fumarate reductase under hypoxia [36,79].”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [76] 76. R.J. Wiesner, P. Rosen, M.K. Grieshaber, Pathways of succinate formation and their contribution to improvement of cardiac-function in the hypoxic rat-heart, Biochem. Med. Metab. Biol. 40 (1988) 19-34. source

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    • cites [77] 77. R.J. Wiesner, A. Deussen, M. Borst, J. Schrader, M.K. Grieshaber, Glutamate degra- dation in the ischemic dog heart -contribution to anaerobic energy-production, J. Mol. Cell. Cardiol. 21 (1989) 49-59. source

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    • cites [36] 36. S.J. Ralph, R. Moreno-Sanchez, J. Neuzil, S. Rodriguez-Enriquez, Inhibitors of suc- cinate: quinone reductase/complex II regulate production of mitochondrial re- active oxygen species and protect normal cells from ischemic damage but induce specific cancer cell death, Pharm. Res. 28 (2011) 2695-2730. source

      Not checked in the free run.

    • cites [79] 79. C. Hohl, R. Oestreich, P. Rosen, R. Wiesner, M. Grieshaber, Evidence for succinate production by reduction of fumarate during hypoxia in isolated adult-rat heart-cells, Arch. Biochem. Biophys. 259 (1987) 527-535. source

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  • May combine two claims.

    Premisecitation

    E. coli SQR exclusively produces superoxide, whereas QFR produces mainly superoxide at lower succinate concentrations and relatively more hydrogen peroxide at higher succinate concentrations.

    “E. coli SQR exclusively produces superoxide.In contrast, E. coli QFR produces mainly superoxide at lower succinate concentrations and comparably more hydrogen peroxide at higher substrate concentrations [101].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [101] 101. K.R. Messner, J.A. Imlay, Mechanism of superoxide and hydrogen peroxide for- mation by fumarate reductase, succinate dehydrogenase, and aspartate oxidase, J. Biol. Chem. 277 (2002) 42563-42571. source

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  • Classified as probably not a substantial claim.

    Premisecitation

    Quinlan et al. proposed that complex II generates ROS only when the flavin is reduced and the carboxylate binding site is unoccupied.

    “They proposed a mechanism for ROS production by complex II that relies upon the occupancy of the carboxylate binding site and the reduction state of the enzyme, i.e.ROS are only generated when the flavin is reduced and the carboxylate binding site is not occupied.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [37] 37. C.L. Quinlan, A.L. Orr, I.V. Perevoshchikova, J.R. Treberg, B.A. Ackrell, M.D. Brand, Mitochondrial complex II can generate reactive oxygen species at high rates in both the forward and reverse reactions, J. Biol. Chem. 287 (2012) 27255-27264. source

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    Premiseown data

    E. coli SQR and QFR show maximal ROS at intermediate succinate concentrations between 0.1 and 1 mM and lower rates at lower and higher substrate concentrations, resembling mammalian and nematode complex II.

    “Furthermore, both enzymes showed maximal rates of ROS at intermediate succinate concentrations between 0.1 and 1 mM and decreased rates at lower and higher substrate concentration, which resembles the dependence found later for mammalian [37] and nematode [100] complex II.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [37] 37. C.L. Quinlan, A.L. Orr, I.V. Perevoshchikova, J.R. Treberg, B.A. Ackrell, M.D. Brand, Mitochondrial complex II can generate reactive oxygen species at high rates in both the forward and reverse reactions, J. Biol. Chem. 287 (2012) 27255-27264. source

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    • cites [100] 100. M.P. Paranagama, K. Sakamoto, H. Amino, M. Awano, H. Miyoshi, K. Kita, Contri- bution of the FAD and quinone binding sites to the production of reactive oxy- gen species from Ascaris suum mitochondrial complex II, Mitochondrion 10 (2010) 158-165. source

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  • May combine two claims.

    Premisecitation

    Complex II activity is regulated by succinate concentration and by TCA cycle intermediates, especially oxaloacetate, which competitively inhibits complex II.

    “The activity of complex II is directly influenced by the concentration of other TCA cycle metabolites, since malate, fumarate, citrate and especially oxaloacetate [65][66][67] have been shown to inhibit competitively with succinate.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [65][66][67]

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  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    The complex II ROS production observed by Quinlan et al. was completely sensitive to malonate and only partially repressed by atpenin A5, leading them to conclude that ROS was produced at the flavin site of complex II.

    “Furthermore, this ROS production was completely sensitive to the competitive carboxylate site inhibitor malonate and was only partially repressed by the Q-site inhibitor atpenin A5.Therefore, the authors concluded that the ROS must have been produced at the flavin site of complex II [37].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [37] 37. C.L. Quinlan, A.L. Orr, I.V. Perevoshchikova, J.R. Treberg, B.A. Ackrell, M.D. Brand, Mitochondrial complex II can generate reactive oxygen species at high rates in both the forward and reverse reactions, J. Biol. Chem. 287 (2012) 27255-27264. source

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Messner and Imlay concluded that QFR releases superoxide from fully reduced flavin if the [2Fe-2S] cluster is available to sequester the semiquinone electron; otherwise the electron is rapidly transferred to nascent superoxide and hydrogen peroxide is released.

    “Messner and Imlay concluded that QFR releases superoxide from the fully reduced flavin if the [2Fe-2S] cluster is available to sequester the semiquinone electron; otherwise this electron is rapidly transferred to the nascent superoxide and hydrogen peroxide is released [101].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [101] 101. K.R. Messner, J.A. Imlay, Mechanism of superoxide and hydrogen peroxide for- mation by fumarate reductase, succinate dehydrogenase, and aspartate oxidase, J. Biol. Chem. 277 (2002) 42563-42571. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Mitochondrial ROS have an ambivalent role in ischemia/reperfusion and preconditioning: they contribute to cellular damage during prolonged ischemia/reperfusion but also participate in cardioprotective signaling during ischemic and pharmacological preconditioning.

    “An ambivalence of mitochondrial ROS production has been also detected in the context of ischemia/reperfusion and ischemic or pharmacological preconditioning: while reactive oxygen species are among the main determinants of cellular damage during longer periods of ischemia and reperfusion, there is also ample evidence that mitochondrial ROS production is involved in cardioprotective signaling”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [8,[38][39][40]

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    Interpretationcitation

    The protective effects of complex II inhibitors can be explained by their differential effects on complex I and complex III ROS production: they reduce complex I reverse-electron-transfer ROS during reperfusion and promote Qo-site complex III ROS by shifting the Q-pool to an intermediate redox state.

    “The protective effects of complex II inhibitors could then be explained by their differential effects on complex I and complex III related ROS production: they reduce ROS that are generated at complex I by reverse electron transfer (RET) during reperfusion while they promote production of ROS at the Q o site of complex III by shifting the redox state of the Q-pool to an intermediate state [15].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [15] 15. S. Dröse, P.J. Hanley, U. Brandt, Ambivalent effects of diazoxide on mitochondrial ROS production at respiratory chain complexes I and III, Biochim. Biophys. Acta 1790 (2009) 558-565. source

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    • Rests on an assumption: The mechanisms of complex II-related ROS production observed in isolated mitochondria, submitochondrial particles, bacteria, and nematodes are representative of mammalian cardiac mitochondria relevant to ischemia/reperfusion and preconditioning.
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    Premisecitation

    In coupled mitochondria and submitochondrial particles, high ROS production with saturating succinate is largely attributable to complex I via reverse electron transfer from complex II, because it is sensitive to complex I inhibitors, requires high membrane potential, and does not occur in uncoupled submitochondrial particles.

    “In coupled mitochondria and SMP, high ROS production is observed under these conditions, but this can be largely attributed to complex I due to reverse electron transfer from complex II, since (i) it is sensitive to complex I inhibitors like rotenone [18][19][20]24,91,92], (ii) requires a high membrane potential, i.e. is sensitive to uncouplers and ionophores [15,[18][19][20]91] or ADP (that”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [18][19][20]24,91,92]

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    • cites [15,[18][19][20]91]

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    • cites [32] 32. S. Dröse, U. Brandt, The mechanism of mitochondrial superoxide production by the cytochrome bc 1 complex, J. Biol. Chem. 283 (2008) 21649-21654. source

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    • cites [93] 93. Q. Chen, E.J. Vazquez, S. Moghaddas, C.L. Hoppel, E.J. Lesnefsky, Production of re- active oxygen species by mitochondria: central role of complex III, J. Biol. Chem. 278 (2003) 36027-36031. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    In adult Ascaris suum submitochondrial particles, succinate-dependent ROS generation was not affected by a complex I inhibitor and was completely or partially suppressed by malonate or atpenin A5, indicating that complex II was the exclusive ROS source under those conditions.

    “The succinate-dependent ROS generation of SMP from adult worms, that do not contain complex III and IV activities in their respiratory chain, was not influenced by a complex I inhibitor and was completely and partially suppressed by malonate or atpenin A5, respectively.This indicates that complex II is the exclusive ROS source under these conditions.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [100] 100. M.P. Paranagama, K. Sakamoto, H. Amino, M. Awano, H. Miyoshi, K. Kita, Contri- bution of the FAD and quinone binding sites to the production of reactive oxy- gen species from Ascaris suum mitochondrial complex II, Mitochondrion 10 (2010) 158-165. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Quinlan et al. observed that complex II in isolated rat skeletal mitochondria produced ROS at a significant rate with succinate concentrations below 5 mM, peaking around 400 micromolar, when the downstream respiratory chain was inhibited.

    “This was also confirmed by Quinlan et al. [37], however these authors also observed that complex II in isolated rat skeletal mitochondria produced ROS at a significant rate with succinate concentrations below 5 mM (with a peak at around 400 μM) and when the downstream respiratory chain was inhibited.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [37] 37. C.L. Quinlan, A.L. Orr, I.V. Perevoshchikova, J.R. Treberg, B.A. Ackrell, M.D. Brand, Mitochondrial complex II can generate reactive oxygen species at high rates in both the forward and reverse reactions, J. Biol. Chem. 287 (2012) 27255-27264. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Complex II-related ROS rates approach or exceed the maximum rates of complexes I and III, suggesting that complex II may be an important contributor to physiological and pathological ROS production.

    “Finally, it was shown that the complex II related rates approach or exceed the maximum rates of complexes I and III indicating that complex II may be an important contributor to physiological and pathological ROS production [37].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [37] 37. C.L. Quinlan, A.L. Orr, I.V. Perevoshchikova, J.R. Treberg, B.A. Ackrell, M.D. Brand, Mitochondrial complex II can generate reactive oxygen species at high rates in both the forward and reverse reactions, J. Biol. Chem. 287 (2012) 27255-27264. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    E. coli SQR and QFR both produce ROS with a linear dependence on dissolved oxygen, although SQR produces ROS at a much lower rate.

    “Both enzymes produced ROS with a linear dependence on the dissolved oxygen concentration, although SQR produced ROS at a much lower rate.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [101] 101. K.R. Messner, J.A. Imlay, Mechanism of superoxide and hydrogen peroxide for- mation by fumarate reductase, succinate dehydrogenase, and aspartate oxidase, J. Biol. Chem. 277 (2002) 42563-42571. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Complex II can oxidize malate to the enol form of oxaloacetate, which binds the dicarboxylate site with high affinity.

    “Besides a direct competition between succinate and malate, it has been observed that complex II can oxidize malate to the enol form oxaloacetate [67,68], which binds to the dicarboxylate binding site with high affinity [66].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [67] 67. B.A.C. Ackrell, E.B. Kearney, M. Mayr, Studies on succinate-dehydrogenase. 24. Role of oxalacetate in regulation of mammalian succinate-dehydrogenase, J. Biol. Chem. 249 (1974) 2021-2027. source

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    • cites [68] 68. Y.O. Belikova, A.B. Kotlyar, A.D. Vinogradov, Oxidation of malate by the mitochon- drial succinate-ubiquinone reductase, Biochim. Biophys. Acta 936 (1988) 1-9. source

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    • cites [66] 66. E.B. Kearney, B.A.C. Ackrell, M. Mayr, Tightly bound oxalacetate and activation of succinated dehydrogenase, Biochem. Biophys. Res. Commun. 49 (1972) 1115-1121. source

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    Interpretationcitation

    Under aerobic conditions, succinate concentrations in tissues and mitochondria are submillimolar, indicating that complex II does not operate at maximal velocity under standard conditions.

    “The succinate concentration in different tissues and mitochondria is in the submillimolar range under aerobic conditions [22,72,73], indicating that complex II is not working at maximal velocity under 'standard conditions'.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [22] 22. A.A. Starkov, The role of mitochondria in reactive oxygen species metabolism and signaling, Ann. N. Y. Acad. Sci. 1147 (2008) 37-52. source

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    • cites [72] 72. S. Hoyer, C. Krier, Ischemia and the aging brain -studies on glucose and energy-metabolism in rat cerebral-cortex, Neurobiol. Aging 7 (1986) 23-29. source

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    • cites [73] 73. K. Brockmann, A. Bjornstad, P. Dechent, C.G. Korenke, J. Smeitink, J.M.F. Trijbels, S. Athanassopoulos, R. Villagran, O.H. Skjeldal, E. Wilichowski, J. Frahm, F. Hanefeld, Succinate in dystrophic white matter: a proton magnetic resonance spectroscopy finding characteristic for complex II deficiency, Ann. Neurol. 52 (2002) 38-46. source

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    Interpretationcitation

    Increased oxidation of the Q-pool explains the increased ROS generation by antimycin A-inhibited complex III, because superoxide generation at the Qo site is maximal at intermediate reduction states of the ubiquinone pool when the Qi site is blocked.

    “This can be explained by an increased oxidation of the Q-pool, since it was shown that the superoxide generation at the Q o site is maximal at intermediate reduction states of the ubiquinone pool if the Q i site is blocked by antimycin A [25,32,33].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [25] 25. L. Bleier, S. Dröse, Superoxide generation by complex III: from mechanistic rationales to functional consequences, Biochim. Biophys, Acta (2013), http://dx.doi.org/10. 1016/j.bbabio.2012.12.002. source

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    • cites [32] 32. S. Dröse, U. Brandt, The mechanism of mitochondrial superoxide production by the cytochrome bc 1 complex, J. Biol. Chem. 283 (2008) 21649-21654. source

      Not checked in the free run.

    • cites [33] 33. C.L. Quinlan, A.A. Gerencser, J.R. Treberg, M.D. Brand, The mechanism of super- oxide production by the antimycin-inhibited mitochondrial Q-cycle, J. Biol. Chem. 286 (2011) 31361-31372. source

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    Premisecitation

    In SQR, high-potential centers are close to the Q site, while in QFR, FAD and the [2Fe-2S] clusters have the highest redox potentials and accumulate electrons near the dicarboxylate binding site.

    “In SQR the high potential centers ([3Fe-4S] and heme b, which attract electrons and pull them away from the dicarboxylate site) are close to the Q site, while in QFR, FAD and the [2Fe-2S] clusters have the highest redox potentials and hence accumulate electrons close to the dicarboxylate binding site.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [12] 12. V. Yankovskaya, R. Horsefield, S. Tornroth, C. Luna-Chavez, C. Leger, B. Byrne, G. Cecchini, S. Iwata, Architecture of succinate dehydrogenase and reactive oxygen species generation, Science 299 (2003) 700-704. source

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  • Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing).

    Premisecitation

    The differential contribution of TCA cycle enzymes and the conditional removal of oxaloacetate are key factors controlling succinate-dependent ROS generation.

    “it was suggested by Muller et al. that the differential contribution of TCA cycle enzymes and the conditional removal of the endogenous complex II inhibitor oxaloacetate are key factors that control succinate-dependent ROS generation [23].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [23] 23. F.L. Muller, Y.H. Liu, M.A. Abdul-Ghani, M.S. Lustgarten, A. Bhattacharya, Y.C. Jang, H. Van Remmen, High rates of superoxide production in skeletal-muscle mitochondria respiring on both complex I-and complex II-linked substrates, Biochem. J. 409 (2008) 491-499. source

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  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Under simultaneous NADH-generating substrate and succinate supply, electrons can flow downstream through complex I, which should attenuate RET.

    “Zoccarato and colleagues have shown that under these conditions electrons can flow downstream through complex I, which should attenuate RET [21].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [21] 21. F. Zoccarato, L. Cavallini, S. Bortolami, A. Alexandre, Succinate modulation of H 2 O 2 release at NADH:ubiquinone oxidoreductase (complex I) in brain mito- chondria, Biochem. J. 406 (2007) 125-129. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing).

    Premisecitation

    Malate reduces succinate-dependent ROS formation via accumulation of oxaloacetate that occurs unless acetyl-CoA is available.

    “They have proposed that the reduction of the succinate-dependent ROS formation by malate is due to an accumulation of oxaloacetate that occurs unless acetyl-CoA is available.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [23] 23. F.L. Muller, Y.H. Liu, M.A. Abdul-Ghani, M.S. Lustgarten, A. Bhattacharya, Y.C. Jang, H. Van Remmen, High rates of superoxide production in skeletal-muscle mitochondria respiring on both complex I-and complex II-linked substrates, Biochem. J. 409 (2008) 491-499. source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    Different NADH-generating substrates have opposing effects on ROS generation.

    “other studies demonstrated that different NADH-generating substrates have an opposing effect on ROS generation [23,35,108]”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [23] 23. F.L. Muller, Y.H. Liu, M.A. Abdul-Ghani, M.S. Lustgarten, A. Bhattacharya, Y.C. Jang, H. Van Remmen, High rates of superoxide production in skeletal-muscle mitochondria respiring on both complex I-and complex II-linked substrates, Biochem. J. 409 (2008) 491-499. source

      Not checked in the free run.

    • cites [35] 35. F. Zoccarato, C. Miotto, L. Cavallini, A. Alexandre, The control of mitochon- drial succinate-dependent H 2 O 2 production, J. Bioenerg. Biomembr. 43 (2011) 359-366. source

      Not checked in the free run.

    • cites [108] 108. S. Bortolami, E. Comelato, F. Zoccarato, A. Alexandre, L. Cavallini, Long chain fatty acyl-CoA modulation of H 2 O 2 release at mitochondrial complex I, J. Bioenerg. Biomembr. 40 (2008) 9-18. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Fully reduced FAD can transfer one electron to molecular oxygen to form superoxide, probably the major reaction in complex II but only confirmed for E. coli SQR, or transfer both electrons to O2 to form hydrogen peroxide, as shown for E. coli QFR.

    “In principle, fully reduced FAD can either transfer one electron onto molecular oxygen which leads to the formation of superoxide (probably the major reaction in complex II, but only confirmed for E. coli SQR [101]) or it may also transfer both electrons onto O 2 which leads to the formation of H 2 O 2 (as shown for E. coli QFR [101]) (Fig. 2B).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [101] 101. K.R. Messner, J.A. Imlay, Mechanism of superoxide and hydrogen peroxide for- mation by fumarate reductase, succinate dehydrogenase, and aspartate oxidase, J. Biol. Chem. 277 (2002) 42563-42571. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Mutants of E. coli SQR lacking heme b showed unchanged ROS generation, indicating that heme b does not serve as a sink for excess electrons.

    “Mutants of E. coli SQR that do not contain heme b showed an unchanged ROS generation, indicating that this prosthetic group is not serving as a 'sink' for excess electrons [102,103].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [102] 102. Q.M. Tran, R.A. Rothery, E. Maklashina, G. Cecchini, J.H. Weiner, Escherichia coli suc- cinate dehydrogenase variant lacking the heme b, Proc. Natl. Acad. Sci. U. S. A. 104 (2007) 18007-18012. source

      Not checked in the free run.

    • cites [103] 103. Q.M. Tran, C. Fong, R.A. Rothery, E. Maklashina, G. Cecchini, J.H. Weiner, Out of plane distortions of the heme b of Escherichia coli succinate dehydrogenase, PLoS One 7 (2012). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Yankovskaya et al. proposed that the key difference in ROS production between E. coli SQR and QFR lies in the differential arrangement of redox potentials among the redox centers.

    “Yankovskaya et al. [12] proposed that the key difference in the ROS production by E. coli SQR and QFR lies in the differential arrangement of redox potentials among the redox centers.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [12] 12. V. Yankovskaya, R. Horsefield, S. Tornroth, C. Luna-Chavez, C. Leger, B. Byrne, G. Cecchini, S. Iwata, Architecture of succinate dehydrogenase and reactive oxygen species generation, Science 299 (2003) 700-704. source

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    The prevalent view is that under these conditions ROS are produced by complex I due to reverse electron transfer from complex II, although alternative explanations have been proposed.

    “While alternative explanations for the source or mechanism of ROS production under these conditions have been proposed [34,36], the prevalent view is that under these conditions ROS are produced by complex I due to RET from complex II [18][19][20]23].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [34] 34. F. Zoccarato, L. Cavallini, A. Alexandre, Succinate is the controller of O 2 -•/H 2 O 2 release at mitochondrial complex I: negative modulation by malate, positive by cyanide, J. Bioenerg. Biomembr. 41 (2009) 387-393. source

      Not checked in the free run.

    • cites [36] 36. S.J. Ralph, R. Moreno-Sanchez, J. Neuzil, S. Rodriguez-Enriquez, Inhibitors of suc- cinate: quinone reductase/complex II regulate production of mitochondrial re- active oxygen species and protect normal cells from ischemic damage but induce specific cancer cell death, Pharm. Res. 28 (2011) 2695-2730. source

      Not checked in the free run.

    • cites [18][19][20]23]

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    These redox arrangements favor the respective physiological activities and also imply a differential disposition for superoxide production under aerobic conditions.

    “While these arrangements favor the respective physiological activity (i.e., ubiquinone reduction for SQR and fumarate reduction/menaquinol oxidation for QFR) they also presuppose a differential disposition for superoxide production under aerobic conditions.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [12] 12. V. Yankovskaya, R. Horsefield, S. Tornroth, C. Luna-Chavez, C. Leger, B. Byrne, G. Cecchini, S. Iwata, Architecture of succinate dehydrogenase and reactive oxygen species generation, Science 299 (2003) 700-704. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    The most likely ROS source in wild-type complex II is the fully reduced FAD, although a Q-site contribution might occur in mutants.

    “While a contribution of the Q site might occur in the respective mutants, the most likely source of ROS in wild-type complex II is the fully reduced FAD [37,101].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [37] 37. C.L. Quinlan, A.L. Orr, I.V. Perevoshchikova, J.R. Treberg, B.A. Ackrell, M.D. Brand, Mitochondrial complex II can generate reactive oxygen species at high rates in both the forward and reverse reactions, J. Biol. Chem. 287 (2012) 27255-27264. source

      Not checked in the free run.

    • cites [101] 101. K.R. Messner, J.A. Imlay, Mechanism of superoxide and hydrogen peroxide for- mation by fumarate reductase, succinate dehydrogenase, and aspartate oxidase, J. Biol. Chem. 277 (2002) 42563-42571. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Atpenin A5-induced ROS generation by complex II is somewhat lower than ROS generation induced by a downstream block at the complex III Qo site, explained by altered succinate dehydrogenase activity upon atpenin A5 binding.

    “However, atpenin A5 induced ROS generation by complex II was somewhat lower than ROS generation induced by a further downstream block (at the complex III Q o site by myxothialzol), which has been explained by an alteration of the succinate dehydrogenase activity upon atpenin A5 binding [37].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [37] 37. C.L. Quinlan, A.L. Orr, I.V. Perevoshchikova, J.R. Treberg, B.A. Ackrell, M.D. Brand, Mitochondrial complex II can generate reactive oxygen species at high rates in both the forward and reverse reactions, J. Biol. Chem. 287 (2012) 27255-27264. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Mitochondria can scavenge large quantities of internally and externally produced ROS, especially hydrogen peroxide.

    “Recent investigations indicate that mitochondria are not only an important source of ROS, but can also scavenge large quantities of internally and externally produced reactive oxygen species, especially hydrogen peroxide [22,[111][112][113][114][115][116].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [22,[111][112][113][114][115][116]

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Inhibition of complex II and attenuation of succinate-supported ROS generation have been shown by Dzeja et al.

    “Accordingly, inhibition of complex II and attenuation of the succinate supported ROS generation have been shown by Dzeja et al. [130].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [130] 130. P.P. Dzeja, P. Bast, C. Ozcan, A. Valverde, E.L. Holmuhamedov, D.G.L. Van Wylen, A. Terzic, Targeting nucleotide-requiring enzymes: implications for diazoxide-induced cardioprotection, Am. J. Physiol. 284 (2003) H1048-H1056.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationreasoning

    Alternatively, substrate flow through the TCA cycle differs depending on substrates, which might affect the activity of NADP+-dependent isocitrate dehydrogenase and malic enzyme.

    “Alternatively, the substrate flow through the TCA cycle differs depending on the substrates, which might affect the activity of the other two mitochondrial NADPH-regenerating enzymes the NADP + -dependent isocitrate dehydrogenase [119,120] and the malic enzyme [118,121].”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [119] 119. L.A. Sazanov, J.B. Jackson, Proton-translocating transhydrogenase and NAD- linked and NADP-linked isocitrate dehydrogenases operate in a substrate cycle which contributes to fine regulation of the tricarboxylic-acid cycle activity in mitochondria, FEBS Lett. 344 (1994) 109-116. source

      Not checked in the free run.

    • cites [120] 120. S.H. Jo, M.K. Son, H.J. Koh, S.M. Lee, I.H. Song, Y.O. Kim, Y.S. Lee, K.S. Jeong, W.B. Kim, J.W. Park, B.J. Song, T.L. Huh, Control of mitochondrial redox balance and cellular defense against oxidative damage by mitochondrial NADP + -dependent isocitrate dehydrogenase, J. Biol. Chem. 276 (2001) 26732. source

      Not checked in the free run.

    • cites [118] 118. J. Rydström, Mitochondrial NADPH, transhydrogenase and disease, Biochim. Biophys. Acta 1757 (2006) 721-726. source

      Not checked in the free run.

    • cites [121] 121. W.H. Ying, NAD + /NADH and NADP + /NADPH in cellular functions and cell death: regulation and biological consequences, Antioxid. Redox Signal. 10 (2008) 179-206. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Uncouplers and complex I inhibitors attenuate ROS-induced damage in ischemia/reperfusion hearts.

    “They identified uncouplers and complex I inhibitors as compounds that attenuate the ROS-induced damage in I/R-hearts.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [123] 123. Q. Chen, A.K.S. Camara, D.F. Stowe, C.L. Hoppel, E.J. Lesnefsky, Modulation of electron transport protects cardiac mitochondria and decreases myocardial in- jury during ischemia and reperfusion, Am. J. Physiol. 292 (2007) C137-C147. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Overall ROS release from isolated mitochondria may appear almost unchanged under antimycin A, but ROS production shifts from complex I to complex III.

    “Hence, the overall ROS release from isolated mitochondria might appear almost unchanged, yet the ROS production is shifted from complex I to complex III.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Ischemic preconditioning can be mimicked by diazoxide and other substances, a phenomenon termed pharmacological preconditioning.

    “Ischemic preconditioning can be mimicked by the K ATP channel opener diazoxide and various other substances, a phenomenon termed pharmacological preconditioning [39].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [39] 39. P.J. Hanley, J. Daut, K ATP channels and preconditioning: a re-examination of the role of mitochondrial K ATP channels and an overview of alternative mechanisms, J. Mol. Cell. Cardiol. 39 (2005) 17-50. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The mitochondrial antioxidative defense system includes the thioredoxin/peroxiredoxin system and the glutathione/glutathione peroxidase system.

    “The highly effective mitochondrial antioxidative defense system encompasses the thioredoxin/peroxiredoxin system as well as the glutathione/glutathione peroxidase system (overview in [22,117]).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [22] 22. A.A. Starkov, The role of mitochondria in reactive oxygen species metabolism and signaling, Ann. N. Y. Acad. Sci. 1147 (2008) 37-52. source

      Not checked in the free run.

    • cites [117] 117. C.C. Winterbourn, M.B. Hampton, Thiol chemistry and specificity in redox sig- naling, Free Radic. Biol. Med. 45 (2008) 549-561. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Diazoxide transiently induces increased ROS production, consistent with mitochondria-derived ROS being involved in cardioprotective signaling during ischemic and pharmacological preconditioning.

    “Diazoxide transiently induces increased ROS production [43,[131][132][133], which is in agreement with the view that mitochondria-derived reactive oxygen species are involved in cardioprotective signaling during ischemic and pharmacological preconditioning (overview in [8,39,40]).”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [43,[131][132][133]

      Not checked in the free run.

    • cites [8] 8. A.P. Halestrap, S.J. Clarke, I. Khaliulin, The role of mitochondria in protection of the heart by preconditioning, Biochim. Biophys. Acta 1767 (2007) 1007-1031. source

      Not checked in the free run.

    • cites [39] 39. P.J. Hanley, J. Daut, K ATP channels and preconditioning: a re-examination of the role of mitochondrial K ATP channels and an overview of alternative mechanisms, J. Mol. Cell. Cardiol. 39 (2005) 17-50. source

      Not checked in the free run.

    • cites [40] 40. L.S. Burwell, S.M. Nadtochiy, P.S. Brookes, Cardioprotection by metabolic shut-down and gradual wake-up, J. Mol. Cell. Cardiol. 46 (2009) 804-810. source

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    Mitochondria are both targets and sources of injury during cardiac ischemia and reperfusion.

    “It has been recognized that the mitochondria are both targets and sources of injury during cardiac ischemia and reperfusion [123].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [123] 123. Q. Chen, A.K.S. Camara, D.F. Stowe, C.L. Hoppel, E.J. Lesnefsky, Modulation of electron transport protects cardiac mitochondria and decreases myocardial in- jury during ischemia and reperfusion, Am. J. Physiol. 292 (2007) C137-C147. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    ROS production under these conditions is attenuated by both classes of complex II inhibitors, uncouplers, ionophores, and complex I inhibitors.

    “ROS production under these conditions is therefore not only attenuated by both classes of complex II inhibitors, but also by uncouplers, ionophores and complex I inhibitors.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Premisecitation

    Ischemic preconditioning, in which brief cycles of ischemia and reperfusion precede prolonged ischemia, reduces damage from ischemia/reperfusion.

    “However, the damage occurring during ischemia/reperfusion (I/R) can be reduced by ischemic preconditioning where the prolonged ischemic period is preceded by one or more brief (2-5 min) cycles of ischemia and reperfusion [8,39,124].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [8] 8. A.P. Halestrap, S.J. Clarke, I. Khaliulin, The role of mitochondria in protection of the heart by preconditioning, Biochim. Biophys. Acta 1767 (2007) 1007-1031. source

      Not checked in the free run.

    • cites [39] 39. P.J. Hanley, J. Daut, K ATP channels and preconditioning: a re-examination of the role of mitochondrial K ATP channels and an overview of alternative mechanisms, J. Mol. Cell. Cardiol. 39 (2005) 17-50. source

      Not checked in the free run.

    • cites [124] 124. D.M. Yellon, J.M. Downey, Preconditioning the myocardium: from cellular phys- iology to clinical cardiology, Phys. Rev. 83 (2003) 1113-1151. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    High succinate concentration and elevated complex II activity suppress ROS generation from FAD but induce superoxide production at complex I due to RET.

    “A high succinate concentration and elevated complex II activity will suppress ROS generation from FAD, but will induce superoxide production at complex I due to RET (Fig. 3A).”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Diazoxide and brief ischemic intervals during early reperfusion improve heart recovery and reduce infarct size, a phenomenon termed postconditioning.

    “Diazoxide as well as several very brief ischemic intervals (10 s) during the early phase of reperfusion also improve the recovery of the heart and reduce infarct size, a phenomenon termed postconditioning [8].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [8] 8. A.P. Halestrap, S.J. Clarke, I. Khaliulin, The role of mitochondria in protection of the heart by preconditioning, Biochim. Biophys. Acta 1767 (2007) 1007-1031. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The Qo site of complex III has been considered a source for mitochondria-derived signaling ROS in several cellular processes including HIF-1α stabilization.

    “This site has been considered as a source for mitochondria-derived 'signaling ROS' in several cellular processes including the stabilization of the hypoxia-inducible factor 1-α [135][136][137].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [135][136][137]

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Diazoxide and ischemic preconditioning-associated ROS production is attenuated by myxothiazol, indicating that the Qo site of complex III is the source.

    “Importantly, diazoxide and ischemic preconditioning associated ROS production is attenuated by myxothiazol [132,134], which clearly indicates that the Q o site of complex III is the source.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [132] 132. O. Oldenburg, M.V. Cohen, J.M. Downey, Mitochondrial K ATP channels in preconditioning, J. Mol. Cell. Cardiol. 35 (2003) 569-575. source

      Not checked in the free run.

    • cites [134] 134. T.L. Vanden Hoek, L.B. Becker, Z. Shao, C. Li, P.T. Schumacker, Reactive oxygen spe- cies released from mitochondria during brief hypoxia induce preconditioning in cardiomyocytes, J. Biol. Chem. 273 (1998) 18092-18098. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    It seems plausible that uncouplers and complex I inhibitors protect by suppressing RET-induced superoxide production by complex I, though Chen et al. suggested complex III as the ROS source.

    “It seems plausible that both substance groups exert their protective effects by suppressing the RET-induced superoxide production by complex I (Section 3.2), but Chen et al. suggested complex III as the source of ROS [123].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [123] 123. Q. Chen, A.K.S. Camara, D.F. Stowe, C.L. Hoppel, E.J. Lesnefsky, Modulation of electron transport protects cardiac mitochondria and decreases myocardial in- jury during ischemia and reperfusion, Am. J. Physiol. 292 (2007) C137-C147. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    A prolonged period of ischemia followed by reperfusion irreversibly damages the heart and other tissues.

    “It is well known that a prolonged period of ischemia followed by reperfusion irreversibly damages the heart and other tissues (overview in [8,9]).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [8] 8. A.P. Halestrap, S.J. Clarke, I. Khaliulin, The role of mitochondria in protection of the heart by preconditioning, Biochim. Biophys. Acta 1767 (2007) 1007-1031. source

      Not checked in the free run.

    • cites [9] 9. D.M. Yellon, D.J. Hausenloy, Mechanisms of disease: myocardial reperfusion in- jury, N. Engl. J. Med. 357 (2007) 1121-1135. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    During ischemia, only a small increase of ROS is detected, but a burst occurs upon reperfusion.

    “During ischemia, only a small increase of ROS has been detected, but a burst occurs upon reperfusion [43,125].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [43] 43. P. Pasdois, B. Beauvoit, L. Tariosse, B. Vinassa, S. Bonoron-Adele, P. Dos Santos, Effect of diazoxide on flavoprotein oxidation and reactive oxygen species gener- ation during ischemia-reperfusion: a study on Langendorff-perfused rat hearts using optic fibers, Am. J. Physiol. 294 (2008) H2088-H2097.

      Not checked in the free run.

    • cites [125] 125. L.G. Kevin, A.K.S. Camara, M.L. Riess, E. Novalija, D.F. Stowe, Ischemic preconditioning alters real-time measure of O 2 radicals in intact hearts with is- chemia and reperfusion, Am. J. Physiol. 284 (2003) H566-H574.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    There is general uncertainty whether applied concentrations in various test systems result in similar effective concentrations, influenced by partition coefficient and membrane permeability.

    “However, there is general uncertainty whether the applied concentration in various test systems will result in similar effective concentrations, which might be largely influenced by the partition coefficient and relative membrane permeability of the applied drug.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationown data

    Diazoxide probably binds to the Qp site of complex II and might directly induce ROS generation at FAD at relatively low succinate concentrations.

    “Alternatively, diazoxide that probably binds to the Qp site of complex II (unpublished results) might directly induce ROS generation at the FAD at relatively low succinate concentrations (Fig. 3C).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites unpublished results

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    Effects of diazoxide on mitochondrial respiration occur at concentrations above those usually applied for mitoKATP opening.

    “It has been pointed out that the effects of diazoxide on mitochondrial respiration occur at concentrations that are above the concentrations that are usually applied for mitoK ATP opening [151].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [151] 151. A.J. Kowaltowski, S. Seetharaman, P. Paucek, K.D. Garlid, Bioenergetic conse- quences of opening the ATP-sensitive K + channel of heart mitochondria, Am. J. Physiol. 280 (2001) H649-H657.

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    It is uncertain whether this mechanism correctly describes ROS generation in vivo.

    “Hence, it is uncertain whether this mechanism correctly describes ROS generation in vivo.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    It was concluded from many investigations that diazoxide targets mitoKATP and that this channel plays a central role in cardioprotection by ischemic and pharmacological preconditioning and by ischemic postconditioning.

    “It was concluded from many investigations that diazoxide targets a mitochondrial form of ATP-dependent K + channels (mitoK ATP ) and that this channel plays a central role in cardioprotection by ischemic and pharmacological preconditioning and by ischemic postconditioning [140][141][142].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [140][141][142]

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    The effect of atpenin A5 was independent of complex II inhibition, and the authors suggested opening of the putative mitoKATP channel as the mechanism.

    “The effect of atpenin A5 was independent of complex II inhibition, and the authors suggested that opening of the putative mitoK ATP channel is the underlying mechanism.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [44] 44. A.P. Wojtovich, P.S. Brookes, The complex II inhibitor atpenin A5 protects against cardiac ischemia-reperfusion injury via activation of mitochondrial K-ATP channels, Basic Res. Cardiol. 104 (2009) 121-129. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S1 (asserted).

    Premisecitation

    An alternative hypothesis relates the cardioprotective effects of atpenins to modulation of mitochondrial ROS production.

    “Hence, an alternative hypothesis was presented that relates the cardioprotective effects of atpenins to the modulation of mitochondrial ROS production [16].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [16] 16. S. Dröse, L. Bleier, U. Brandt, A common mechanism links differently acting com- plex II inhibitors to cardioprotection: modulation of mitochondrial reactive ox- ygen species production, Mol. Pharmacol. 79 (2011) 814-822. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    A model was presented that merges the two conflicting views, i.e., that complex II may be a component or regulator of the mitoKATP channel.

    “Recently, a model was presented that merges these two conflicting views, i.e. that complex II may be a component or regulator of the mitoK ATP channel [44,156,157].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [44] 44. A.P. Wojtovich, P.S. Brookes, The complex II inhibitor atpenin A5 protects against cardiac ischemia-reperfusion injury via activation of mitochondrial K-ATP channels, Basic Res. Cardiol. 104 (2009) 121-129. source

      Not checked in the free run.

    • cites [156] 156. H. Ardehali, Z.H. Chen, Y. Ko, R. Mejia-Alvarez, E. Marban, Multiprotein complex containing succinate dehydrogenase confers mitochondrial ATP-sensitive K + channel activity, Proc. Natl. Acad. Sci. U. S. A. 101 (2004) 11880-11885. source

      Not checked in the free run.

    • cites [157] 157. A.P. Wojtovich, P.S. Brookes, The endogenous mitochondrial complex II inhibitor malonate regulates mitochondrial ATP-sensitive potassium channels: implications for ischemic preconditioning, Biochim. Biophys. Acta 1777 (2008) 882-889. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    KATP channel subunits could not be identified in highly purified mitochondria, challenging the existence of mitoKATP.

    “Especially, the fact that the K ATP channel subunits could not be identified so far in highly purified mitochondria challenges its existence [145,146].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [145] 145. T. Brustovetsky, N. Shalbuyeva, N. Brustovetsky, Lack of manifestations of diazoxide/5-hydroxydecanoatesensitive K ATP channel in rat brain nonsynaptosomal mitochondria, J. Physiol. Lond. 568 (2005) 47-59. source

      Not checked in the free run.

    • cites [146] 146. D.B. Foster, J.J. Rucker, E. Marban, Is Kir6.1 a subunit of mitoK ATP ? Biochem. Biophys. Res. Commun. 366 (2008) 649-656. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Diazoxide inhibits complex II, while the KATP channel antagonist 5-HD can be metabolized by mitochondrial β-oxidation.

    “Diazoxide inhibits complex II [128,129,147], while the K ATP channel antagonist 5-HD can be metabolized by the ß-oxidation pathway of the mitochondria [148][149][150].”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [128] 128. P.J. Hanley, M. Mickel, M. Löffler, U. Brandt, J. Daut, K ATP channel-independent targets of diazoxide and 5-hydroxydecanoate in the heart, J. Physiol. 542 (2002) 735-741. source

      Not checked in the free run.

    • cites [129] 129. S. Dröse, U. Brandt, P.J. Hanley, K + -independent actions of diazoxide question the role of inner membrane K ATP channels in mitochondrial cytoprotective sig- naling, J. Biol. Chem. 281 (2006) 23733-23739. source

      Not checked in the free run.

    • cites [147] 147. S. Ovide-Bordeaux, R. Ventura-Clapier, V. Veksler, Do modulators of the mito- chondrial K ATP channel change the mitochondria in situ? J. Biol. Chem. 275 (2000) 37291-37295. source

      Not checked in the free run.

    • cites [148][149][150]

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The existence of a mitoKATP channel is controversial.

    “However, the existence of such a mitoK ATP channel is controversial [8,39,[142][143][144].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [8,39,[142][143][144]

      Not checked in the free run.

65 of 65
  • The paper relies on this without support.

    The mechanisms of complex II-related ROS production observed in isolated mitochondria, submitochondrial particles, bacteria, and nematodes are representative of mammalian cardiac mitochondria relevant to ischemia/reperfusion and preconditioning.

    “It is important to note that the overall structural and functional similarity of E. coli SQR and QFR to mammalian complex II has made them useful models systems for structure-function investigations and the analysis of disease-related human mutations [14].”
1 of 1

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • In sub-mitochondrial particles, CII can produce ROS upon Qp site inhibition only when FAD is reduced and the dicarboxylate site is unoccupied.

    “In sub-mitochondrial particles, it has been previously established that CII can produce ROS upon Q p site inhibition only when FAD is reduced and the dicarboxylate site is unoccupied.7,38”

    From Ubiquinone-binding site mutagenesis reveals the role of mitochondrial complex II in cell death initiation (2015) · cites this paper as [38]

    Section 3.1 states that complex II generates ROS when FAD is reduced and the dicarboxylate site is unoccupied; the Conclusions say Qp-site inhibitors can promote ROS production from the flavin site. But the paper presents the occupancy-and-reduction mechanism as proposed, not established specifically in submitochondrial particles. Its discussion of the relevant mammalian experiments identifies isolated mitochondria as the preparation. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

Cites

Flagged first, then by citations

1 of the 158 references couldn’t be matched to a known paper.

Cited by

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Authors
Dröse, S.
Affiliations
Goethe University Frankfurt (DE)
Corresponding author
Dröse, Stefan
Venue
Biochimica et Biophysica Acta (BBA) - Bioenergetics
Publisher
Elsevier BV
Published
2013-05
Volume
1827
Issue
5
Pages
578-587
ISSN
0005-2728 (ISSN-L)
OpenAlex
W2084933852
Cited by
201
References
158
Citations by year
2026: 4 · 2025: 11 · 2024: 14 · 2023: 16 · 2022: 23 · 2021: 19 · 2020: 21 · 2019: 13 · 2018: 23 · 2017: 14 · 2016: 14 · 2015: 14 · 2014: 12 · 2013: 3
FWCI
2.11
Type
journal article
Language
en
Open access
Locations
  • Biochimica et Biophysica Acta (BBA) - Bioenergetics (publishedVersion)
  • PubMed (publishedVersion)
Funders
Deutsche Forschungsgemeinschaft (SFB815)
Topics
  • Health Sciences › Medicine › Pathology and Forensic Medicine › Cardiac Ischemia and Reperfusion
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Mitochondrial Function and Pathology
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Coenzyme Q10 studies and effects
Keywords
succinate dehydrogenase, succinate-ubiquinone oxidoreductase, mitochondrial reactive oxygen species, cardioprotection, preconditioning, postconditioning, ischemia-reperfusion injury, respiratory burst, TCA cycle, oxaloacetate, electron transport chain, cardiomyocytes
MeSH terms
Electron Transport, Humans, Mitochondria, Models, Biological, Succinates, Myocardial Reperfusion Injury, Reactive Oxygen Species, Ischemic Preconditioning, Myocardial, Electron Transport Complex II

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-09-30.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-09-30.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

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