EKA/B-mediated platelet aggregation is dependent on ADP and TXA₂ release. Platelets were stimulated with EKA/B (5 μM) in the presence of indomethacin (10 μM) or vehicle control (Me₂SO, A), SQ294890 or vehicle control (Tyrode-HEPES buffer, B), cangrelor (AR-C69931MX) or vehicle control (Tyrode-HEPES buffer, C), or MRS2179 or vehicle control (Tyrode-HEPES buffer, D), and aggregation was measured under constant stirring conditions at 37°C. Washed platelets were stimulated with subaggregatory concentrations of EKA/B (1.25 μM) alone, thrombin (Thr.; 0.005 U/mL), collagen (Coll.; 0.5 μg/mL), adrenaline (Adr.; 10 μM), or 5-HT (10 μM) in combination with EKA/B (1.25μM) or vehicle control (acetic acid 0.001%), and aggregation was measured at 37°C under constant stirring conditions (E). Individual aggregation traces are representative of 3 separate experiments (A,E). Numerical data represent means plus or minus SEM. (n = 3); **P < .01; ***P < .001.