Amrinone relaxes potassium-induced contracture of failing right ventricular muscle of cats

Marion S. Gaide, William S. Fitterman, Jay R. Wiggins, Robert J. Myerburg, John S. Cameron, Arthur L. Bassett

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

The effects of amrinone (5.3 X 10 -4 M) on isometric contraction and K +-induced contracture force of right ventricular muscle isolated from normal cats (n = 6) and cats in right ventricular failure (RVF, n = 6), 3-14 days after partial pulmonary artery ligation, were studied. Peak isometric contractile force (P(o) and maximal rate of force development (dP/dt) of RVF muscles (1.38 ± 0.21 g/mm 2; X̄ ± SEM, and 1 ± 11 ± 1 g/s/mm 2, respectively) were significantly lower than normal muscles (2.46 ± 0.41 g/mm 2, p < 0.025, and 24 ± 3 g/s/mm 2, p < 0.005, respectively). Duration of contraction (DC) was significantly lower in RVF muscles (442 ± 32 ms) than in normal muscles (361 ± 11 ms, p < 0.025). Times to peak twitch force (TTP) and peak K +-induced contracture force ((JP(c)) of RVF and normal muscles were not different. Amrinone increased P(o) and dP/dt significantly in normal muscles (+78 ± 24%; X̄ ± SEM; p < 0.01, and +53 ± 17%, p < 0.025, respectively), but not in RVF muscles (+11 ± 16% and +8 ± 19%, respectively). TTP and DC of normal muscle were unchanged by amrinone, whereas TTP was unchanged while DC was shortened (-12 ± 3%, p < 0.025) in RVF muscle. Amrinone relaxed P(c) similarly and significantly in normal (-28 ± 7%, p < 0.005) and RVF (-26 ± 4%, p < 0.025) muscles. These results suggest that part of amrinone's salutary action in the failing heart occurs through modification of myocardial relaxation.

Original languageEnglish (US)
Pages (from-to)335-340
Number of pages6
JournalJournal of Cardiovascular Pharmacology
Volume5
Issue number2
DOIs
StatePublished - 1983

Keywords

  • Amrinone
  • Cardiac failure
  • Isolated ventricular muscle
  • Isometric contraction
  • K-contracture
  • Pressure-overloaded muscle

ASJC Scopus subject areas

  • Pharmacology
  • Cardiology and Cardiovascular Medicine

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