Hydrogen Peroxide Induces Cardiomyocyte Apoptosis Via Triggering Endoplasmic Reticulum Stress

Objective: Oxidative stress as external factors can directly induce cardiomyocyte apoptosis, but also involved in myocardial apoptosis mediated regulation of gene expression and intracellular signal transduction pathways. Another study shows that the development of cardiovascular disease is present in the control mechanism of endoplasmic reticulum stress (ERS). Whether the apoptosis of cardiomyocyte induced by oxidative stress is related to the ERS is not well known.Methods: The cultured H9C2 cells were divided into 2 groups: low concentrations (100μM H₂O₂) and the high concentration (500μM H₂O₂) at different time points. The cell apoptosis ratio was detected by flow cytometry and observed the typical cardiomyocyte apoptosis by hematoxylin-eosin staining (HE) and Hoechest staining methods. We also detect the expression of ERS marker proteins p-PERK and CHOP by Western Blotting. Furthermore,we use the chemical chaperone PBA (4-phenylbutyric acid) to ERS in myocardial cells and detect the expression of p-JNK,p-PERK and CHOP by western Blotting. We also detect the activities of Caspase-12 and Caspase-3 by flow cytometry.Results: (1) The highest rate of apoptosis was observed in the myocardial cells treated with H₂O₂ (100μM) for 8 hours. (2) The myocardial cells showed the typical apoptotic morphology: cell membranes remained intact, but the nucleus occurred condensation, marginalization. (3)The expression of ERS marker protein p-PERK and CHOP were significantly higher than the H₂O₂ group. (4) PBA can effectively inhibit cardiomyocyte apoptosis induced by H₂O₂. The expression of ERS marker protein p-PERK and CHOP were significantly decreased compared to the H₂O₂ group (P <0.01). The activities of caspase-3 and caspase-12 were also significantly reduced (P <0.01).Conclusion: The low concentration of H₂O₂ (100μM) significantly induced the apoptosis of myocardial cells and high concentrations of H₂O₂ (500μM) have resulted in myocardial necrosis; low concentrations of H₂O₂ induced the cardiomyocyte apoptosis via triggering ERS regulation mechanism. Our results could provide new ideas for prevention and treatment of cardiovascular disease.