The Study Of Effect And Mechanisms Of LipoxinA₄on Hypoxia/Reoxygenation Cardiomyocytes

Part1:Protective role of overexpression of HO-1induced by lipoxin A4on hypoxia/reoxygenation lesion of myocardiac cellsObjective:We ultized the H9C2cardiomyocytes subjected to hypoxia/reoxygenation in a serum-free medium in vitro simulating ischemia/repufusion in vivo,which were treated by LipoxinA4, to investigate the roles of lipoxin A4in attenuating myocardial hypoxia/reoxygenation lesion and the possible mechanisms.Methods:The cells were divided into five groups:control group, H/R group, LXA4+H/R group, ZnPP+H/R group, LXA4+ZnPP+H/R group. Lesion of the cells was observed.The levels of LDH and CK in cellular supernatants were measured,and activity of HO-1was measured. HO-1mRNA expression was analyzed by RT-PCR.Results:Pretreatment of the cells undergoing hypoxia/reoxygenation lesion with LXA4significantly reduced the LDH and CK levels, avoid the necrosis of the cells, and increased the expression of HO-1mRNA and activity of HO-1as compared with those in the cells without pretreatment with LXA4. However, HO-1inhibition by ZnPP abolished the protective role of LXA4on the cells undergoing hypoxia/reoxygenation lesion. Conclusion:LXA4can induce HO-1overexpression which provide the protective role on myocardiac cells undergoing hypoxia/reoxygenation lesion. Part2:Potassium channels participate in protection of LXA4on hypoxia/reoxygenation lesion of myocardiac cellsObjective:Close behind the first experimenial palt, we established the hypoxia/reoxygenation model of H9C2cardiomyoeytes, which were pretreated by inhibitors of potassium channels, to investigate the role of potassium channels of protection on hypoxia/reoxygenation lesion of myocardiac cells by LXA4.Methods:H9C2cardiomyoeytes were respectively pretreated by Glibenclamide (inhibitor of ATP-sensitive potassium channel)、5-hydroxydecanoate(specific inhibitor of mitochondrial ATP-sensitive potassium channel)and Paxilline(inhibitor of calcium-sensitive potassium channel)、we observe the influence of lesion of myocardiac cells and the expression of HO-1after potassium channels were inhibitted with the protection of LXA4on hypoxia/reoxygenation lesion of myocardiac cells. The levels of LDH and CK in cellular supernatants were measured. HO-1mRNA expression was analyzed by RT-PCR..Western blot analysis was used to measure the expression of HO-1in the H9C2cardiomyoeytes.Results:Compared with the control group, pretreatment of the cells undergoing hypoxia/reoxygenation lesion with LXA4significantly reduced the LDH and CK levels, increased the expression of HO-1mRNA and protern.In G+H/R group、5+H/R group、 P+H/R group, LDH and CK levels increased,and the HO-1mRNA and protern expressions reduced as compared with H/R group.However, in the corresponding three group with pretreated of LXA4, LDH and CK levels reduced,and the HO-1mRNA and protern expressions increased.Conclusion:Mitochondrial ATP-sensitive potassium channel and calcium-sensitive potassium channel participate in protection of LXA4on hypoxia/reoxygenation lesion of myocardiac cells. AS the potassium channel be inhibited, the protection of LXA4on hypoxia/reoxygenation lesion of myocardiac cells is blocked.