Verapamil inhibition of 5-hydroxytryptamine (5HT) uptake in rat platelets

The effect of verapamil on 5-hydroxytryptamine (5HT) uptake into rat blood platelets was investigated in vitro. Verapamil produced a non-competitive inhibition (IC50 = 8.2 +/- 0.5 microM) of 5HT uptake. The administration of verapamil to rats also produced inhibition of 5HT uptake and reduced the concentration of this amine in the platelets. The present data indicate that verapamil has an influence on the uptake processes for 5HT in blood platelets in rats.