Evidence for the existence of 5-hydroxytryptamine receptors, which are not of the 5-HT2 type, mediating contraction of rabbit isolated basilar artery

Abstract

In the rabbit isolated basilar artery the contractile action of 5-hydroxytryptamine (5-HT) was little affected by high concentrations of ketanserin (1.0 × 10⁻⁶ M) indicating that 5-HT-receptors other than those of the 5-HT₂-type were involved. The contractile action of 5-HT was mimicked by methysergide and 5-carboxamidotryptamine (5-CT) with equipotent concentration ratios (5-HT = 1) of about 22 and 0.6 respectively. This profile is characteristic of that in the dog saphenous vein which contains a 5-HT receptor type that may be described as ‘5-HT₁-like’.