Action potential duration and force-frequency relationship in isolated rabbit, guinea pig and rat cardiac muscle

P. Szigligeti, C. Pankucsi, T. Bányász, A. Varró, P. P. Nánási

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

The effect of action potential duration and elevated cytosolic sodium concentration on the force-frequency relationship in isolated rabbit, guinea pig and rat papillary muscle preparations was studied. Shortening of action potential duration in guinea pig and rabbit from 150-200 ms to values characteristic of rat (20-40 ms), using the K(ATP) channel activator levkromakalim (15 μmol · l-1), markedly reduced the force of contraction and converted the positive force-frequency relationship into negative one at longer pacing cycle lengths. This conversion was greatly enhanced in the presence of acetylstrophanthidin (0.2 l μmol · l-1), an inhibitor of the Na-K pump. Acetylstrophanthidin (1 μmol · l-1) alone, however, had no effect on the force-frequency relationship. Prolongation of action potential duration in rat with inhibitors of cardiac K channels (4- aminopyridine [10 mmol · l-1] plus tetraethylammonium [2 mmol · l-1]) increased the force of contraction and abolished the negative force-frequency relationship observed in rat at longer pacing-cycle lengths. It is concluded that both action potential duration and cytosolic sodium concentration are major determinants of the force-frequency relationship in mammalian myocardium.

Original languageEnglish
Pages (from-to)150-155
Number of pages6
JournalJournal of Comparative Physiology - B Biochemical, Systemic, and Environmental Physiology
Volume166
Issue number2
DOIs
Publication statusPublished - Jun 1996

Keywords

  • Action potential duration
  • Force of contraction
  • Frequency- dependence
  • Intracellular calcium concentration
  • Mammalian Cardiac muscle

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Biochemistry
  • Physiology
  • Animal Science and Zoology
  • Endocrinology

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