Cholera toxin-induced changes in force of contraction and cyclic AMP levels in canine ventricular myocardium: Inhibition by carbachol

Masao Endoh, Masahiko Maruyama, Teruyuki Yanagisawa

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Cholera toxin (1-10 μg/ml) had a biphasic inotropic action on the isolated canine ventricular muscle: it produced a transient negative and a long lasting positive inotropic effect. The negative effect reached a maximum 43 + 2 min (n = 12) after administration of the toxin, while it took 3-5 hrs for the positive effect to reach a steady level. The positive inotropic effect of cholera toxin was accompanied by a prominent abbreviation of the time to peak tension and the relaxation time of individual contractions. The level of adenosine 3′,5′-cyclic monophosphate (cyclic AMP) of the tissue was elevated by cholera toxin in a time- and concentration-dependent manner. Carbachol (1 μmol/l) administered 3 or 5 hrs after the administration of cholera toxin (10 μg/ml) reversed the increase in force of contraction and the elevation of cyclic AMP levels induced by cholera toxin. These results indicate that cholera toxin exerts a cyclic AMP-dependent positive inotropic effect and a negative inotropic effect which is not related to cyclic AMP levels in canine ventricular myocardium.

Original languageEnglish
Pages (from-to)2397-2406
Number of pages10
JournalLife Sciences
Volume35
Issue number24
DOIs
Publication statusPublished - 1984 Dec 10

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)

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