Effects of cadmium treatment in vitro on the uptake and release of [3H]serotonin by human blood platelets.

Effects of cadmium treatment on human platelets were studied with respect to uptake and release of 5-[3H]hydroxytryptamine (5-HT). The uptake of 5-[3H]HT in the presence of varying concentrations of CdCl2 (0.001-10 mM) was inhibited significantly with respect to control platelets and the inhibition was maximum at 1 mM CdCl2 concentration. From studies on the kinetics of 5-[3H]HT uptake a higher Km and significantly lower Vmax for CdCl2-treated platelets were observed. CdCl2 stimulated spontaneous release but inhibited thrombin-induced release of 5-[3H]HT. Spontaneous release of 5-[3H]HT induced by CdCl2 was not significantly altered in the presence of externally available CaCl2 (1 mM).