The effects of quercetin protect cardiomyocytes from A/R injury is related to its capability to increasing expression and activity of PKCε protein

Quercetin is a ubiquitous flavonoid found in vegetable foods. Epidemiological and animal studies have reported an inverse association between quercetin intakes and occurrence and development of various cardiovascular diseases. Some researchers have inferred that the mechanisms of quercetin to protect cardiomyocytes from ischemia/reperfusion injury may be involved in modulation of intracellular signal pathways and regulation of proteins expression beyond its antioxidant activity. The aim of this study was to investigate whether quercetin protect cardiomyocytes from anoxia/reoxygenation injury through PKC epsilon pathway. Neonatal rat primary cardiomyocytes were pretreated with quercetin or quercetin plus epsilon V1-2, a selective PKC epsilon inhibitor, prior to A/R treatment. Western blotting analysis showed that the level of PKC epsilon and phosphor-PKC epsilon Ser297 in the quercetin pretreatment group were all increased significantly compared to the control or A/R group. Subsequent assays showed that pretreated with quercetin could increase the viability of neonatal rat primary cardiomyocytes suffered A/R, decrease the apoptosis and ROS and alleviate the loss of mitochondrial membrane potential induced by A/R injury. However, the protective effects of quercetin disappeared in the group pretreated with epsilon V1-2. Thus, for the first time, we revealed that one of the mechanisms of quercetin protecting cardiomyocytes from A/R injury might be increase the expression of PKC epsilon protein and then enhance the activity of its downstream pathway.