Flavonoids from Chinese Viscum coloratum produce cytoprotective effects against ischemic myocardial injuries: inhibitory effect of flavonoids on PAF-induced Ca2+ overload.

Viscum coloratum has been used in the indigenous system of medicine for the treatment of various diseases such as myocardial ischemia and arrhythmia. Platelet-activating factor (PAF) is an important player in cardiovascular diseases. The aim of this study was to investigate the protective effects of Viscum coloratum flavonoids (VCF) against ischemic myocardial injuries in vivo and to further investigate its regulatory effect on PAF. Studies were performed in a rat model of myocardial infarction and in isolated myocytes. It was found that VCF relieved myocardial injuries during ischemia. PAF (10(-11) m) significantly increased the intracellular free Ca2+ concentration ([Ca2+]i) and VCF inhibited the changes induced by PAF in single cardiac myocytes. The results suggest that VCF can improve cardiac function and that VCF reduces ischemic myocardial injuries via blocking the signaling pathway of PAF. Therefore, PAF blockers may be candidate drugs for preventing cardiac injuries during ischemia/reperfusion, and subsequently improving cardiac function.