5-Hydroxytryptamine contracts human coronary arteries predominantly via 5-HT2 receptor activation.

5-Hydroxytryptamine (5-HT) caused contractions of human isolated epicardial coronary arteries which were markedly antagonised by ketanserin (10 nM-1 microM). The antagonism was not competitive. The selective 5-HT1-like receptor agonist, GR43175, caused only small, ketanserin-resistant contractions. These results suggest that the predominant contractile effect of 5-HT in human isolated large coronary arteries is mediated via 5-HT2 receptors but that, in addition, 5-HT1-like receptors contribute to some degree to this response in vitro.