Abstract
5-Hydroxytryptamine (5-HT) stimulated prostacyclin release, measured by radioimmunoassay as 6-keto-prostaglandin F 1 α , from rat aorta in a dose-dependent manner (3 × 10 −7 − 10 −4 M). A statistically significant stimulation was observed at concentrations higher than 3 × 10 −6 M. Norepinephrine also increased prostacyclin release but only at a high concentration (10 −4 M) and histamine (3 × 10 −5 and 10 −4 M) had no significant effect. Among some structurally 5-HT-related analogues, only tryptamine exhibited a dose-dependent stimulatory effect on prostacyclin release but it was slightly less potent than 5-HT. Tryptophan and 5-hydroxytrytophan had no effects whereas 5-hydroxyindoleacetic acid at 10 −4 M stimulated slightly. Prostacyclin release stimulated by 5-HT was depressed by non-specific 5-HT antagonists, methysergide, mianserin and cyproheptadine. In contrast, a specific 5-HT 2 antagonist ketanserin (3 × 10 −7 − 10 −5 M) had no antagonistic effect. These results suggest that 5-HT stimulates the release of prostacyclin from rat aorta by interaction with receptors distinct from its 5-HT 2 subtype.
Published Version
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