The effect of drugs upon the uptake of 5-hydroxytryptamine and metaraminol by human platelets

Abstract

Abstract The abilities of some tricyclic and bicyclic antidepressive drugs and an α-receptor blocking agent, phenoxybenzamine, to inhibit the uptake of 5-hydroxytryptamine (5-HT) and (—)-metaraminol into human platelets have been compared in vitro. All the drugs inhibited the uptake both of 5-HT and of metaraminol into platelets. But there were differences in their abilities to inhibit the uptake of these two monoamines. The desmethylated antidepressive drugs were more potent inhibitors of metaraminol uptake than were their tertiary analogues, whereas imipramine, a tertiary amine, was by far the best inhibitor of 5-HT uptake. The order of the activities of the antidepressive drugs in inhibiting the uptake of 5-HT and metaraminol into platelets paralleled their potencies in blocking the uptake of 5-HT, and noradrenaline or metaraminol into nerve endings. It is suggested that the uptake of 5-HT and metaraminol into platelets is a useful model for the neuronal uptake of 5-HT and noradrenaline, respectively.