Inhibitory effects of bacterial endotoxin and reserpine on the uptake of 3H-5-hydroxytryptamine by granule fractions of blood platelets

Abstract

In rabbit platelets, bacterial endotoxin (lipopolysaccharide), at a concentration of 10 −4 g/ml, inhibited the uptake of 3H-5HT by platelets, especially by the granule fraction. Reserpine, at a concentration of 10 −7 g/ml, counteracted the uptake of 3H-5HT by platelets, especially by the granule fraction. It was discussed that there were two different mechanisms operating in the storage granule of 5HT: The one is the uptake mechanism of the exogenous 5HT and the other is the upkeep mechanism of the endogenous 5HT. Although reserpine is able to impair both mechanisms, the 5HT uptake mechanism is more susceptible to the low concentration of reserpine than the 5HT upkeep mechanism. On the other hand, bacterial endotoxin seems to inhibit more markedly the 5HT upkeep mechanism than the uptake mechanism.