[Effect of forskolin, isoprenaline and propranolol on spontaneous contractions of the isolated atrium of guinea pigs].
Forskolin (0.375 mumol 1(-1)) produced positive inotropic and chronotropic effects on the isolated, spontaneously beating atria of the guinea pig. The same effects were also observed or even increased in the presence of various concentrations of isoprenaline (0.024 and 0.12 mumol 1(-1)) in the organ bath. The effects of forskolin on the isometric contraction and the atrial rate of the isolated, spontaneously beating atria of the guinea-pig were significantly inhibited by propranolol (9 mumol 1(-1)). These results indicate that the action of forskolin on the spontaneously beating atria of the guinea-pig is mediated by stimulation of the adenylate cyclase system, but in some steps of this action, a direct stimulation of beta-adrenoceptors might also be implicated.
D000818:Animals; D005576:Colforsin / Q000494:pharmacology*; D004347:Drug Interactions; D005260:Female; D006168:Guinea Pigs; D006325:Heart Atria / Q000187:drug effects; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D011433:Propranolol / Q000494:pharmacology*
D005576:Colforsin; D011433:Propranolol; D007545:Isoproterenol
Action de la forskoline, de l'isoprénaline et du propranolol sur les contractions spontanées de l'oreillette isolée du cobaye.