Secreted ADP plays a central role in thrombin-induced phospholipase D activation in human platelets.

Thrombin and other agonists that induce secretion and aggregation in human platelets also activate phospholipase D (PLD), but the signaling cascade leading to activation of PLD in human platelets is not yet clear. We have determined that apyrase, which scavenges ADP secreted during platelet activation, is able to block or reduce the PLD activation stimulated by low (0.1 U/ml or less) or high (0.