Inotropic effects of endothelin on mammalian ventricular contractility.
Endothelin-1 elicited a concentration-dependent positive inotropic effect on the isolated rabbit, guinea pig, and rat, but not on the dog ventricular myocardium. The duration of isometric contractions was prolonged by endothelin-1 in a concentration-dependent manner, mainly by prolongation of relaxation time. Phorbol 12,13-dibutyrate (PDBu) (a tumor-promoting phorbol ester) inhibited the positive inotropic effect of endothelin-1, as well as myocardial alpha 1-adrenoceptor stimulation at low concentrations (10(-9) mol/l and above) without (10(-8) mol/l) or less (10(-7) mol/l) affecting the basal force of contraction, and the positive inotropic effect of beta-adrenoceptor stimulation. The present findings indicate that endothelin elicits a positive inotropic effect on mammalian ventricular myocardium, the characteristics of which are very similar to those of myocardial alpha-adrenoceptor stimulation.
Endoh
M
M
Department of Pharmacology, Yamagata University School of Medicine, Japan.
Takanashi
M
M
D000818:Animals; D002046:Bupranolol / Q000494:pharmacology; D004285:Dogs; D016232:Endothelins / Q000494:pharmacology*; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000187:drug effects; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D010210:Papillary Muscles / Q000187:drug effects / Q000502:physiology; D010656:Phenylephrine / Q000494:pharmacology; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D016276:Ventricular Function
D016232:Endothelins; D010656:Phenylephrine; D015240:Phorbol 12,13-Dibutyrate; D002046:Bupranolol; D007545:Isoproterenol; D011224:Prazosin