Effects of quercetin on aggregation and intracellular free calcium of platelets

AIM: To study the effects of Que on the intraplatelet free calcium concentration and the effects of calcium on the inhibition of platelet aggregation by Que. METHODS: Using Quin-2 fluorescence technique. RESULTS: Que inhibited the platelet aggregation and the rise of [Ca2+]i induced by thrombin in platelets. The values of IC50 and 95% confidence interval were 146.2 (92.4 - 231.3) and 78.5 (49.5 - 124.4) mumol.L-1, respectively. The inhibitory effects of Que on platelet aggregation induced by thrombin were reduced by adding calcium to the medium, and Que had no effect on thrombin-induced internal Ca2+ release from dense tubular system. CONCLUSION: The inhibitory effects of Que on aggregation and the rise of [Ca2+]i in platelets was mainly due to an inhibition of Ca2+ influx.