Abstract
In pithed guinea-pigs, general characteristics and the origin of the tachycardia produced by intravenous injection of 5-hydroxytryptamine (5-HT) were analysed. The study was undertaken to provide evidence that the tachycardia results not only from the direct cardiac action of 5-HT, but also from its indirect sympathicomimetic action. The tachycardic response to 5-HT (25-200 μg/kg) was considerable, long-lasting and dose-dependent. During the depolarizing block of the sympathetic ganglia and the adrenal medulla evoked by nicotine, the 5-HT-induced tachycardia was significantly reduced. Moreover, in animals pretreated with reserpine, bretylium or 6-hydroxydopamine the tachycardia was significantly diminished. There was not a significant difference between the reduction of the tachycardic response to 5-HT produced by 6-hydroxydopamine and that produced by nicotine or reserpine. It is concluded that in guinea pigs the positive chronotropic effect of 5-HT is partly due to the release of noradrenaline from sympathetic nerve terminals as the consequence of the activation of cardiac sympathetic ganglia by 5-HT.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 288-289 |
| Number of pages | 2 |
| Journal | IRCS Medical Science |
| Volume | 10 |
| Issue number | 4 |
| State | Published - Jan 1 1982 |
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)