Abstract: Abstract Objective To investigate the H2O2 pretreatment on mouse myocardial hypoxia/reoxygenation caused apoptosis of H9C2 cells. Methods Mice cardiac cells (H9C2) cultured in vitro amplification, using the logarithmic growth phase cells to do the experimental treatment. Use respectively 0, 5, 10, 20, 50, 100 μ mol/L concentration H2O2 treatment H9C2 cells, flow cytometry ( FCM ), MTT and immunoblotting method ( Western blot ) detection of H2O2 with different concentration on H9C2 cell apoptosis rate, Proliferation activity and the STAT3 phosphorylation level effects, in order to determining the optimal concentration of H2O2 pretreatment. Watch the effects of low concentrations of H2O2 pretreatment on hypoxia/reoxygenation caused cell injury. Cells were divided into four groups namely control group, hypoxia/reoxygenation group, H2O2 pretreatment group, AG490 group.① Control group: conventional cultivation; ② hypoxia/reoxygenation group: pre in 5% CO2, 95%N2 incubator 120min, reoxygenation 30min; ③H2O2 pretreatment groups: pre-treatment given to determine the concentration of H2O2 90min for liquid 24h after hypoxia/ reoxygenation; ④AG490 group: give 10min before the H2O2 pretreatment 10μmol/L AG490 treatment, after treatment with H2O2 pretreatment group.AnnexinV-FITC / PI double staining method and flow cytometry (FCM) detection of apoptosis, MTT assay H9C2 cell proliferation activity, immunoblot (Western blot method) to detect STAT3 phosphorylation level. Results 20μmol/L group of STAT3 phosphorylation significantly higher than all other level of concentration group (P < 0.01), myocardial cell apoptosis rates were also significantly lower than 50 μ mol/L and 100 μ mol/L concentration group (P < 0.01), and the myocardial cell proliferation activity and cell apoptosis rate and 5 μ mol/L and 10 μ mol/L concentration group there were no obvious difference ； H2O2 pretreatment can reduce the small rat myocardial cells apoptosis (P <0.05), increased myocardial cell viability (P<0.05) increased P-STAT3 expression (P<0.05). Oxygen injury to AG490 after treatment can make the H2O2 pretreatment protection disappear.Conclusions 20μmol/L H2O2 pretreatment on myocardial hypoxia/reoxygenation injury adaptive protection. The possible mechanism is activated JAK2-STAT3 pathways play to the role of inhibiting cell apoptosis.

Key words: H2O2 pretreatment, ischemia-reperfusion injury, H9C2 myocardial cells, hypoxia/reoxygenation, JAK2-STAT3