Figure 4.

Representative aggregometer tracings of washed platelet aggregation experiments showing the interactions of ADP and epinephrine. (a) Wild-type platelets were treated with 1 μM epinephrine (top curve) or 2 μM ADP (bottom curve). (b) SP1999-null platelets were treated with 1 μM epinephrine (top curve) or 0.3 U/ml thrombin (bottom curve). (c) SP1999-null platelets were treated with 2 μM ADP (top curve) or a combination of 2 μM ADP and 1 μM epinephrine (bottom curve). Platelets from four mice were pooled and resuspended in modified Tyrode’s buffer supplemented with 1 mM aspirin and 200 μg/ml fibrinogen for each experiment. Aggregation was determined using a Chrono-Log aggregometer. Each experiment was performed three times with similar results.