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Cited by 66Cardiac electrophysiology and arrhythmiasIon channel regulation and functionIon Transport and Channel Regulation

Effects of K+ and K+-induced polarization on (dV/dt)max, threshold potential, and membrane input resistance in guinea pig and cat ventricular myocardium.

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Kishida, H, Surawicz, B, Fu, L T·1979·Circulation Research
DOI 10.1161/01.res.44.6.800
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Abstract

We studied the non-membrane potential-dependent effect of K+ on (dV/dt)max and threshold potential in guinea pig and cat ventricular myocardium. Membrane potential (MP) was changed uniformly in segments (length less than or equal to 1.0 mm) of papillary muscles by applying extracellular polarizing current pulses across a single sucrose gap. Control [K+]o was 5.4 mM and test [K+]o values were 2.0, 10.0, 11.5, 13.0, 16.2, 20, 22, and 24.0 mM. Each muscle was studied under four conditions: (1) control [K+]o and unaltered (control level) resting MP (Em); (2) one of the test [K+]o values and the unaltered (test level) Em; (3) the same test [K+]o and Em held at the control level; (4) control [K+]o and Em held at the test level. At all [K+]o greater than or equal to 11.5 mM, (dV/dt)max showed a decrease significantly (P less than 0.01) greater than the corresponding MP-dependent decrease in both guinea pig and cat myocardium. This non-MP-dependent decrease averaged 7.5% at 11.5 mM, 26.5% at 13.0 mM, 37.2% at 16.2 mM, and 22.7% at 20.0 mM. At [K+]o greater than or equal to 20.0 mM, (dV/dt)max was predominantly slow-channel-dependent; it was increased by hyperpolarization to -110 mV at [K+]o = 20 and 22 mM but not at [K+]o = 24mM. Threshold potential became progressively less negative with increasing [K+]o, but this effect was dependent only on MP. The membrane input resistance (rm) was determined by two opposing factors: at a given [K+]o, rm increased with depolarization; and at a given MP, rm decreased with increasing [K+]o. Our study shows that non-MP-dependent depression of (dV/dt)max in the ventricular myocardium occurs at [K+]o concentrations that may be encountered in vivo.

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  • Mild hyperkalemia lowers the resting membrane potential more than it reduces the threshold potential, leading to increased cellular excitability and enhanced conduction.

    “Mild hyperkalemia lowers the resting membrane potential (making it less negative) more than it reduces the threshold potential. This diminishes their difference, leading to increased cellular excitability and enhanced conduction [24, 25].”

    From Clinical Significance and Management of Atrioventricular Block Associated With Bradycardic/Antiarrhythmic Drug Therapy: Drug-Induced or Drug-Revealed? (2025) · cites this paper as [24]

    The Threshold Potential section (p. 13) reports that increasing extracellular potassium makes the threshold potential less negative, with changes paralleling the resting membrane potential. It does not establish that mild hyperkalemia changes the resting potential more than the threshold or that this enhances excitability and conduction. Clinical Implications (p. 13) instead discusses depressed action-potential upstroke and a possible effect on conduction velocity in severe hyperkalemia. (LLM, conf=0.84)

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  1. Carmeliet EE: The potassium and chloride permeability in Purkinje fibers. In The Specialized Tissue of the Heart. Amsterdam, Elsevier, 1961, pp 108–114

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Related

Authors
Kishida, H., Surawicz, B., & Fu, L. T.
Venue
Circulation Research
Publisher
Ovid Technologies (Wolters Kluwer Health)
Published
1979-06
Volume
44
Issue
6
Pages
800-814
ISSN
  • 0009-7330 (ISSN-L)
  • 1524-4571
DOI
10.1161/01.res.44.6.800
OpenAlex
W1989569821
Cited by
66
References
26
Citations by year
2025: 2 · 2023: 2 · 2021: 3 · 2020: 1 · 2019: 2 · 2017: 3 · 2016: 5 · 2015: 2 · 2014: 3
FWCI
4.35
Type
journal article
Language
en
Open access
Locations
  • Circulation Research (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Cardiac electrophysiology and arrhythmias
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Ion channel regulation and function
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Ion Transport and Channel Regulation
Keywords
potassium, extracellular potassium, membrane potential, ventricular myocardium, threshold potential, membrane input resistance, slow channel, hyperpolarization, papillary muscle, cardiac excitation, potassium depolarization, guinea pig, cats, species differences, cardiac refractory period, arrhythmia risk
MeSH terms
Action Potentials, Animals, Cats, Electric Stimulation, Guinea Pigs, Heart Conduction System, Heart Ventricles, Membrane Potentials, Microelectrodes, Myocardium, Papillary Muscles, Potassium, Potassium Chloride, Purkinje Fibers, In Vitro Techniques

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