[Role of 5-HT2 receptors in the positive chronotropic action of serotonin on the isolated atria in rats].
5-hydroxytryptamine (5-HT), from the concentration of 5 microM to 50 microM has a positive chronotropic activity on the rat isolated atria. The tyramine-like indirect sympathomimetic effect is the main mechanism of the 5-HT action at high concentration (50 microM). In this study, we have demonstrated that 5-HT2 receptor stimulation is also involved in the 5-HT-induced increase in atrial rate. Thus, when the tyramine-like effect was inhibited by reserpine, which causes a noradrenaline depletion of atria, the positive chronotropic effect of 5-HT (50 microM) was reduced but not abolished. The remaining response to 5-HT was completely inhibited by the 5-HT2 antagonist ketanserin (1 microM). Moreover, the increase in atrial rate induced by 5-HT, at the lower concentration of 5 microM, was fully abolished by this antagonist.
Laboratoire de Pharmacodynamie, Université Paris-Sud, Faculté de Pharmacie, Châtenay-Malabry, France.
C
C
el Rawadi
R
R
Haddad
M
M
Davy
M
M
Midol-Monnet
Y
Y
Cohen
D000818:Animals; D016275:Atrial Function / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects*; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000494:pharmacology; D012702:Serotonin Antagonists
D012702:Serotonin Antagonists; D012701:Serotonin; D007650:Ketanserin
Rôle des récepteurs 5-HT2 dans l'action chronotrope positive de la sérotonine sur les oreillettes isolées de rat.