Abstract: Objective:To investigate the effect of knockdown of EphB1 gene on the oxidative damage of cardiomyocytes (H9c2) induced by hydrogen peroxide (H₂O₂) in the rats, and to provide the evidence for EphB1 gene in the treatment of cardiovascular diseases. Methods:The rat cardiomyocytes H9c2 were cultivated in vitro and divided into blank group (no treatment), H₂O₂ group (H₂O₂-induced cell damage), negative control group (transfected with siRNA control) and si-EphB1 transfection group (transfected with si-EphB1 after H₂O₂-induced cell damage). The expression levels of EphB1 mRNA in the H9c2 cells in various groups were detected by fluorescence quantitative real-time polymerase chain reaction (qRT-PCR), the survival rates of the H9c2 cells in various groups were tested by MTT assay, the apoptosis of H9c2 cells were measured by flow cytometry, the ROS levels in the H9c2 cells in various groups were determined by DCFH-DA, and the levels of MDA and SOD in the H9c2 cells in various groups were determined by spectrophotometer. Results:Compared with blank group, the expression level of EphB1 mRNA in the H9c2 cells in H₂O₂ group were significantly increased(P<0.05);the expression level of EphB1 mRNA in the H9c2 cells in negative control group had no change(P>0.05); compared with H₂O₂ group,the expression level of EphB1 mRNA in the H9c2 cells in si-EphB1 transfection group was significantly decreased(P<0.05).Compared with blank group,the survival rate of H9c2 cells in H₂O₂ group was decreased(P<0.05), the apoptotic rate was increased(P<0.05), the ROS and MDA levels were increased(P<0.05), and the SOD level was decreased(P<0.05);but the differences in the survival rate, apoptotic rate, ROS, MDA and SOD levels in negative control group were not significant(P>0.05).Compared with H₂O₂ group, the survival rate of H9c2 cells in si-EphB1 transfection group was increased(P<0.05), the apoptotic rate was decreased(P<0.05), the ROS and MDA levels were decreased(P<0.05), and the SOD level was increased(P<0.05). Conclusion:Knockdown of EphB1 gene can significantly inhibit the H₂O₂-induced oxidative damage of the rat cardiomyocytes and protect against myocardial injury; its mechanism is related to improving the survival rate of cardiomyocytes, inhibiting the apoptosis, improving the antioxidant enzyme activity, and increasing the scavenging abilities of oxidative stress products in the cells.

Key words: erythropoietin-producing hepatocellular receptor gene, cardiomyocytes, oxidative stress, cell proliferation, apoptosis