Abstract： Objective To investigate the effect of Berberine on hypoxia-reoxygenation induced injury of cardiomyocytes.Methods The models of cardiomyocytes with hypoxia-reoxygenation induced injury were established.The cardiomyocytes were divided into the normal group (normal culture),model group (hypoxia-reoxygenation treatment),Berberine group (1 h before hypoxia-reoxygenation treatment,pretreatment with 50 μmol/L Berberine),Berberine+PMA group (pretreatment with 50 μmol/L Berberine and 1 μmol/L nuclear factor-κB (NF-κB) signal activator PMA at 1 h before hypoxia-reoxygenation treatment).Western blotting was used to determine the change of protein expression level of NF-κ Bp65 in each group.The Berberine and NF-κB signal activator were used to treat cardiomyocytes with hypoxia-reoxygenation induced injury.MTT was used to examine cell proliferation.Dinitrophenyl hydrazine colorimetry was used to examine the leakage rate of LDH.Annexin V-FITC/PI double staining was used to determine cell apoptosis.The protein expression levels of Cleaved Caspase-3 and Cleaved Caspase-9 were determined by Western blotting.Xanthine oxidation was used to determine SOD activity.Thiobarbituric acid assay was used to examine the MDA level.Results The protein level of NF-κB p65 in cardiomyocytes treated with hypoxia-reoxygenation increased,the activity of cell proliferation decreased,the LDH leakage rate increased,the apoptosis rate increased,the protein expression levels of Cleaved Caspase-3 and Cleaved Caspase-9 increased,the SOD activity decreased,and the MDA level increased.Berberine could reduce the protein expression level of NF-κB p65 in cardiomyocytes under hypoxia-reoxygenation,increase activity of cell proliferation,decrease LDH leakage rate,reduce cell apoptosis and protein expression levels of Cleaved Caspase-3 and Cleaved Caspase-9,increase SOD activity,and reduce MDA level.The treatment with NF-κB signal activator could reverse the effect of Berberine on the proliferation of cardiomyocytes with hypoxia-reoxygenation induced injury,LDH leakage rate,apoptosis,and the levels of SOD and MDA.Conclusion Berberine may inhibit hypoxia-reoxygenation induced injury of cardiomyocytes by down-regulating the level of NF-κB signaling activation.