Serotonin and Platelet Aggregation in Patients with Essential Hypertension Compared with a Normotensive Control Group

Serotonin is a naturally occurring amine with vasoactive and platelet aggregating properties. It may be involved in the pathogenesis of hypertension. Almost all the serotonin circulating in blood is stored in platelets. Serotonin and other platelet contents are released from platelets during platelet aggregation, which occurs in a stepwise manner. Initially there is a reversible change in platelet shape from a disc to a spiny sphere, and then platelet clumping, and finally a release of platelet contents (Holm sen 1977). The contents of the dense granules, including serotonin, adenosine diphosphate, adenosine triphosphate, calcium and inorganic pyrophosphate, are released before the contents of the a granules, which include ~-thromboglobulin, platelet factor 4, acid hydro lases and fibrinogen (DeClerck 1986; Holmsen et al. 1977). Serotonin released during platelet aggregation could cause vasoconstriction, increased blood pressure and further platelet aggregation. The object of this study was to compare serotonin-induced and spontaneous platelet aggregation in whole blood, platelet serotonin content and plasma ~-thromboglobulin in patients with untreated essential hypertension and in a normotensive control group.