Influence of phospholipase A2 on human blood platelet alpha adrenergic receptor function.

Exposure of platelets to phospholipase A2 selectively obliterates the aggregation response of human platelets to the action of epinephrine. This treatment does not impair the affinity of the ligand binding although it reduces the number of sites available on platelets. Reduction in the number of alpha receptors caused by phospholipase treatment in no way affected the epinephrine-induced restoration of sensitivity of refractory platelets to the action of agonists.