RELATIONSHIPS BETWEEN SERUM-LIPIDS, SEROTONIN, PLATELET-AGGREGATION AND SOME FIBRINOLYTIC PARAMETERS IN HUMANS

We have studied relationships between serum lipids, plasma serotonin ( 5-hydroxytryptamine, 5-HT), platelet aggregation in the platelet-rich plasma (PRP), and some fibrinolytic parameters in healthy volunteers. LDL was positively related to 5-HT-induced platelet aggregation. Highe r serum HDL levels were related to higher fibrinolytic activity expres sed by shorter euglobulin clot lysis time (ECLT). No correlation exist ed between serum lipids and plasma 5-HT. Plasma 5-HT was found to be r elated to tissue plasminogen activator (t-PA), suggesting some link be tween plasma serotonin and the release of t-PA from endothelial cells. There were mutual relations among fibrinolytic parameters such as tis sue plasminogen activator (t-PA) antigens, total plasminogen activator inhibitor-1 (PAI-1), t-PA-PAI-1 complex, free PAI-1, and ECLT. In con clusion higher LDL may be more thrombogenic due to enhanced 5-HT induc ed platelet aggregation whereas high HDL may be more protective agains t thrombosis due to enhancement of fibrinolysis.