Platelet formation of 12-hydroxyeicosatetraenoic acid and thromboxane B2 is increased in type IIA hypercholesterolemic subjects.

The formation of the major metabolic products of endogenous arachidonic acid (AA) via cyclooxygenase and lipoxygenase pathways in platelets from normal and type IIA hypercholesterolemic subjects was evaluated. 12-Hydroxyeicosatetraenoic acid (12-HETE) and thromboxane B2(TXB2) were determined by selected ion monitoring (SIM) after extraction and purification of collagen stimulated platelet-rich plasma (PRP). The levels of both arachidonic acid metabolites in the non-stimulated PRP of control and type IIA subjects were below the detection limit of the method, rising significantly after collagen stimulation. Both 12-HETE and TXB2 levels in collagen-stimulated PRP samples from the patients were significantly higher than levels in controls (P less than 0.001). In view of the key role of 12-HETE in mediating smooth muscle cell migration and proliferation and in stimulating macrophage activity, these data may provide information for the understanding of the elevated incidence of thrombosis and atheromatous lesion in patients with type IIA hypercholesterolemia.