Cited by 35Nitric Oxide and Endothelin EffectsBiochemical and Molecular ResearchFolate and B Vitamins Research

Deficient BH4production via de novo and salvage pathways regulates NO responses to cytokines in adult cardiac myocytes

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Ionova, Irina A., Vásquez-Vivar, Jeannette, Whitsett, Jennifer, Herrnreiter, Anja, Medhora, Meetha, Cooley, Brian C., Pieper, Galen M.·2008·American Journal of Physiology-Heart and Circulatory Physiology

Abstract

Adult rat cardiac myocytes typically display a phenotypic response to cytokines manifested by low or no increases in nitric oxide (NO) production via inducible NO synthase (iNOS) that distinguishes them from other cell types. To better characterize this response, we examined the expression of tetrahydrobiopterin (BH 4)-synthesizing and arginine-utilizing genes in cytokine-stimulated adult cardiac myocytes. Intracellular BH 4 and 7,8-dihydrobiopterin (BH 2) and NO production were quantified. Cytokines induced GTP cyclohydrolase and its feedback regulatory protein but with deficient levels of BH 4 synthesis. Despite the induction of iNOS protein, cytokine-stimulated adult cardiac myocytes produced little or no increase in NO versus unstimulated cells. Western blot analysis under nonreducing conditions revealed the presence of iNOS monomers. Supplementation with sepiapterin (a precursor of BH 4) increased BH 4 as well as BH 2, but this did not enhance NO levels or eliminate iNOS monomers. Similar findings were confirmed in vivo after treatment of rat cardiac allograft recipients with sepiapterin. It was found that expression of dihydrofolate reductase, required for full activity of the salvage pathway, was not detected in adult cardiac myocytes. Thus, adult cardiac myocytes have a limited capacity to synthesize BH 4 after cytokine stimulation. The mechanisms involve posttranslational factors impairing de novo and salvage pathways. These conditions are unable to support active iNOS protein dimers necessary for NO production. These findings raise significant new questions about the prevailing understanding of how cytokines, via iNOS, cause cardiac dysfunction and injury in vivo during cardiac inflammatory disease states since cardiac myocytes are not a major source of high NO production.

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Crossref · 10.1152/ajpheart.00748.2008

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  • In conditions in which dihydrofolate reductase is inactive or absent, recovery of eNOS coupling by sepiapterin supplementation is ineffective.

    “In conditions in which dihydrofolate reductase is inactive or absent, the recovery of eNOS coupling by sepiapterin supplementation is ineffective (452).”

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Authors
Ionova, I. A., Vásquez-Vivar, J., Whitsett, J., Herrnreiter, A., Medhora, M., Cooley, B. C., & Pieper, G. M.
Affiliations
Medical College of Wisconsin (US)
Venue
American Journal of Physiology-Heart and Circulatory Physiology
Published
2008-11
Volume
295
Issue
5
Pages
H2178-H2187
ISSN
  • 0363-6135 (ISSN-L)
  • 1522-1539
OpenAlex
W2143404494
Cited by
35
References
68
Citations by year
2023: 1 · 2022: 2 · 2021: 2 · 2020: 2 · 2019: 1 · 2018: 1 · 2017: 1 · 2016: 1 · 2015: 3 · 2014: 5 · 2013: 1 · 2012: 1
FWCI
3.16
Type
journal article
Language
en
Open access
Locations
  • American Journal of Physiology-Heart and Circulatory Physiology (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
National Heart, Lung, and Blood Institute (R01HL069996, HL-069996, HL078937, R01HL067244, R01HL078937, HL067244)
Topics
  • Health Sciences › Medicine › Physiology › Nitric Oxide and Endothelin Effects
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Biochemical and Molecular Research
  • Health Sciences › Medicine › Rheumatology › Folate and B Vitamins Research
Keywords
tetrahydrobiopterin, nitric oxide production, inducible nitric oxide synthase, cardiomyocytes, cytokine induction, GTP cyclohydrolase, sepiapterin, dihydrofolate reductase, 7,8-dihydrobiopterin, cardiac allograft, cardiac inflammation, cardiac dysfunction
MeSH terms
Alcohol Oxidoreductases, Animals, Arginase, Biopterins, Cells, Cultured, GTP Cyclohydrolase, Male, Nitric Oxide, Proteins, Pterins, Rats, Inbred Lew, Rats, Inbred WF, RNA, Messenger, Tetrahydrofolate Dehydrogenase, Time Factors, Heart Transplantation, Cytokines, Rats, Sprague-Dawley, Phosphorus-Oxygen Lyases, Myocytes, Cardiac, Intracellular Signaling Peptides and Proteins, Rats, Nitric Oxide Synthase Type II

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