In pithed rats, general characteristics and the nature of the positive chronotropic response to intravenous administration of 5-hydroxytryptamine (5-HT) were analysed. 5-HT (25-200 μg/kg), immediately after injection, produced a quick, significant, dose-dependent, but short-lasting increase in heart rate. The tachycardia was not affected during the depolarizing block of the sympathetic ganglia and the adrenal medulla induced by nicotine. In rats pretreated with either reserpine or 6-hydroxydopamine the increase in heart rate was not significantly altered. Cyproheptadine produced a dose-dependent supression of the positive chronotropic response to 5-HT, while slightly potentiating the control tachycardia evoked by noradrenaline. It is concluded that in rats the increase in heart rate caused by 5-HT (25-100 μg/kg) results mainly from the activation of 5-HT receptors in cardiac tissue.
|Original language||English (US)|
|Number of pages||2|
|Journal||IRCS Medical Science|
|State||Published - Jan 1 1981|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)