Figure 1.

Effect of P2Y1 receptor-selective antagonists on 10 μM ADP-induced platelet aggregation. Human platelets were washed and resuspended in Tyrode’s buffer, and aggregation was measured in the absence of added extracellular calcium, as described in Experimental Procedures. (A) Representative traces of various concentrations of A3P5PS on ADP-induced aggregation of aspirin-treated and washed platelets (8). Additions are shown with an arrow. Concentrations of A3P5PS are shown on the right. (B) Effect of P2Y1 receptor-selective antagonists on the extent of ADP-induced aggregation. The extent of aggregation in the presence of antagonists was normalized to that in the absence of the antagonist (taken as 100%).