Effects of quercetin on platelet and reperfusion-induced arrhythmias in rats.

The role of platelets in reperfusion arrhythmias (RA) and the efficacy of quercetin (Que) in preventing the arrhythmias were investigated in anesthetized rats. Platelet count (PC) was performed, the ultrastructure of platelets was scrutinized, and the levels of thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha (Keto-PGF1 alpha) in plasma were determined by radioimmunoassay (RIA). The pretreatment with Que (5 mg.kg-1) 2 min prior to reperfusion inhibited RA. Que remarkably improved the ultrastructural deviation of platelet, inhibited the platelet aggregation and thromboxane A2 (TXA2) formation, and increased the prostacyclin (PGI2) generation and the ratio of PGI2/TXA2. The decrease in PC and increase in TXB2 level in plasma indicated the participation of platelets in the arrhythmogenic activity of ischemia and reperfusion. The results showed that Que produced a protective effect against RA probably through inhibiting the platelet aggregation, TXA2 formation and increasing the PGI2 generation.