Molecular link between membrane cholesterol and cyclic nucleotides in human platelets.

Because of the unresolved complex role of membrane cholesterol content in platelet activity, the present study was addressed to understand two specific issues; firstly whether variation in membrane cholesterol content could influence cyclic nucleotide levels within platelets, and secondly whether the membrane cholesterol modulated cyclic nucleotide levels were mediated through phospholipase A2 activation. The results of this in vitro study revealed that membrane cholesterol not only had the inherent capacity to induce changes in the levels of cyclic nucleotides within human platelets but also that this effect was mediated through its ability to modulate phospholipase A2 activity. Based on these results we suggest that membrane cholesterol modulated phospholipase A2 activity may be the molecular link between the membrane cholesterol content and cyclic nucleotides within human platelets.