Objective:To investigate the effect of oxidative stress on high glucose-induced apoptosis in neonatal rat cardiomyocytes. Methods:MTT assay was carried out to detect the viability of cultrured cardiomyocytes exposed to different concentrations of glucose ranging from 10 mmol/L to 50 mmol/L. Laser confocal microscopy,TUNEL assay and flow cytometry were designed to observe and detect cellular apoptosis. Cardiomyocytes were randomly divided into three groups:the control group,the high glucose group and the antioxidant group. Oxidative stress was evaluated by detecting levels of LDH,MDA and SOD in the supernatant of culture media. Results:High glucose was found to inhibit cardiomyocyte viability in a concentration-dependent manner. The results of laser confocal microscopy,TUNEL assay and flow cytometry all suggested that high glucose can induce cardiomyocyte apoptosis. Our findings showed significant increase of LDH and MDA levels and decrease of SOD activity in the high glucose group compared with the control group. However,in the antioxidant group,LDH and MDA levels decreased and SOD activity increased significantly compared with those in the high-glucose group. The apoptotic rate of cardiomyocytes in the high glucose group increased significantly compared with that in the control group,while the apoptotic rate in the antioxidant group declined remarkably in comparison with that in the high glucose group. Conclusion:Oxidative stress is an important mechanism for high glucose-induced cardiomyocyte apoptosis.