Indirect sympathicomimetic component in the 5-hydroxytryptamine-induced tachycardia in guinea pigs

M. K. Krstic, Z. S. Katusic

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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 languageEnglish (US)
Pages (from-to)288-289
Number of pages2
JournalIRCS Medical Science
Issue number4
StatePublished - 1982

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology


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