Quantitative determination of serotonin released from human platelets

A high-performance liquid chromatographic technique has been used for measuring the amount of endogenous serotonin (5-hydroxytryptamine, 5-HT) released from human platelets stimulated by adenosine diphosphate (ADP) and collagen. Four minutes after challenge both agents induce maximal and similar 5-HT releases corresponding to 14% (ADP) and 17% (collagen) of the intraplatelet 5-HT content. ADP and collagen seem to have different mechanisms of inducing secretion, documented by the different relationship between the release patterns and the optical tracings for aggregation. Endogenous 5-HT release might be useful tool for monitoring states of platelet activation.