Abstract: Objective:To investigate the protective effect of salvianolic acid B on the cardiomyocytes of the suckling rats with oxidative stress injury, and to clarify its mechanism. Methods:The cardiomyocytes of Wistar suckling ratswere primary cultured in vitro and randomly divided into normal control group, model group, low dose of salvianolic acid B group, and high dose of salvianolic acid B group. Except normal control group, the suckling rat cardiomyocytes were induced to oxidative stress injury by being exposed to H₂O₂ at the dose 100 μmoL·L^-1; 20 and 40 μmol·L^-1 salvianolic acid B were separatly added into low and high doses of salvianolic acid B groups. After co-culturing for 4 h, the morphological changes of cardiomyocytes were observed by light microscope;the survival rate of cardiomyocytes was examined using MTT. The levels of reductive glutathione (GSH), the activity of superoxide dismutase (SOD) and the level of malondialdehyde (MDA) in the cardiomyocytes were detected with spectrophotometry. The levels of lactate dehydrogenase(LDH) and creatine kinase (CK) in culture medium were determined by ELISA. Results:Compared with normal control group, the cardiomyocytes in model group partially suspended in the culture medium, the number of adherent cells was decreased, the pseudopod contraction and the volume were decreased, and the self-discipline throb of cardiomyocytes was slow. Compared with model group,the number of cardiomyocytes in 20 and 40 μmol·L^-1 salvianolic acid B groups were increased significantly, the pseudopod contraction was reduced, and self-discipline throb was enhanced. Compared with normal control group, the survival rate of cardiomyocytes in model group was decreased(P<0.01), the level of GSH in cardiomyocytes was decreased(P<0.01), the level of MDA was increased (P<0.01),the activity of SOD was decreased(P<0.01), and the levels of CK and LDH in culture medium were increased (P<0.05 or P<0.01). Compared with model group, the survival rates of cardiomyocytes in 20 and 40 μmol·L^-1 salvianolic acid B groups were increased(P<0.05 or P<0.01), the levels of GSH and the activities of SOD were increased(P<0.05 or P<0.01), the levels of MDA were decreased (P<0.05 or P<0.01),and the CK and LDH levels in culture medium were decreased (P<0.05 or P<0.01). Conclusion:Salvianolic acid B can protect the cardiomyocytes against oxidative stress injury, and its mechanism may be associated with the inhibition of lipid peroxidatic reaction and the enhancement of antioxidant ability of cardiomyocytes.

Key words: salvianolic acid B, cardiomyocytes, oxidative stress injury, myocardial enzyme