SOME PROPERTIES OF 5‐HYDROXYTRYPTAMINE RECEPTORS IN THE HINDQUARTERS OF THE RAT

Abstract

The rat hindquarter preparation, as described, responds with reproducible vasoconstriction to noradrenaline and tryptamines. The receptors involved in these responses are distinct. Evidence of heterogeneity of tryptamine receptors was not obtained. The 5‐hydroxytryptamine (5‐HT) antagonists, methysergide and cyproheptadine, although very potent, displayed antagonism of a non‐competitive type whereas a series of phenothiazines and phentolamine displayed competitive antagonism against 5‐HT. For the phenothiazines the order of increasing potency was promazine < chlorpromazine < triflupromazine. 1979 British Pharmacological Society