Sex related differences in platelet TxA2 generation.

Platelet lipid composition, c arachidonic acid (AA) metabolism by platelets (stimulated with thrombin), serum thromboxane (Tx)B2 production and plasma lipid composition were investigated in 53 healthy females (18-45 years) and 65 males (19-45 years) with similar dietary habits. In males, serum TxB2 production and cholesterol platelet membrane levels were found significantly higher (p less than 0.001 and p less than 0.05) than in females. No differences were observed between the two groups in the AA conversion through cyclo-oxygenase and lipoxygenase pathways or in the platelet phospholipid fatty acid composition. These findings indicate that in males the platelet proaggregatory capacity is greater than in females and the higher platelet TxB2 production does not depend on a larger AA availability or on enzyme activation for its conversion. The increased TxB2 production may be, at least in part, induced by functional differences such as a different membrane cholesterol content inducing, in its turn, an increased microviscosity and/or higher number of platelet receptors for thrombin.