Effects of chlorprothixene isomers on platelet 5-hydroxytryptamine receptors: evidence for different 5-hydroxytryptamine conformations at uptake and stimulatory sites

Abstract

The thioxanthene neuroleptic, cis-chlorprothixene, was approximately 200 times more potent than its transisomer as an inhibitor of the aggregation of human blood platelets induced by 5-hydroxytryptamine (5HT). Against the active uptake of 5HT by these cells, however, trans-chlorprothixene was twice as inhibitory as its cisisomer, and this inhibition was found to be competitive. It is suggested that 5HT adopts different conformations for binding to its two platelet receptors.