(A) Platelet activation by thrombin for 480 seconds causes a significant reduction in subsequent convulxin-induced calcium response. This effect was apparent for doses of thrombin (1 – 10 nM) treatment of diluted (12%), apixaban-treated PRP. (B) Platelet activation by ADP does not significantly attenuate subsequent convulxin-induced calcium response. (C) Platelet activation by the thromboxane analog, U46619, did not significantly attenuate subsequent convulxin-induced calcium response. (C, convulxin; T, thrombin; A, ADP; U, U46619).