Effects of Hypoxia Postconditioning on Mitochondrial Reactive Oxygen Species and Cardiomyocyte Apoptosis Induced by Hypoxia/Reoxygenation

Aim To investigate the effect of hypoxia postconditioning on mitochondrial reactive oxygen species(ROS) and cardiomyocyte apoptosis induced by hypoxia/reoxygenation.Methods The model of cultured cardiomyocytes with hypoxia/reoxygenation(H/R) was established and the cardiomyocytes were divided into 3 groups,including control group,H/R group(hypoxia 3 h and reoxygenation 6 h),and hypoxia postconditioning(PC) group(3 intermittent cycles of 5 min H/R immediately after hypoxia 3 h,then reoxygenation for 6 h).Cardiac mitochondria and sarcolemma were isolated by differential centrifugation.ROS was detected with fluorescent probes and cardiomyocyte apoptosis was detected with flow cytometry.The expressions of Bcl-2 and Bax proteins in the cardiac mitochondria and sarcolemma were measured by Western blot.Results Both mitochondrial ROS and the number of apoptotic cardiomyocytes reduced significantly in PC group compared with H/R group.Bcl-2 levels increased while Bax levels decreased in cardiac mitochondria and sarcolemma of PC group.ConclusionPC attenuated ROS and cardiomyocyte apoptosis induced by H/R,which potentially mediated by upregulating the expression of Bcl-2 and downregulating the Bax in mitochondria and sarcolemma.