脂联素对大鼠缺血再灌注心肌缝隙连接蛋白43表达的影响

目的: 观察脂联素(APN)对大鼠缺血再灌注心肌缝隙连接蛋白43(Cx43)表达的影响,进一步探讨其抗心律失常的可能机制。方法: 将48只雄性Wistar大鼠随机分成:(1)假手术 (SM)组;(2)缺血再灌注(I/R)组:结扎冠状动脉左前降支,30 min后松开结扎线,再灌注120 min;(3)脂联素+缺血再灌注组1(I/R+APN1):先阻断血流30 min,于再灌注120 min开始时给予3.5 μg/kg APN;(4)脂联素+缺血再灌注组2(I/R+APN2):缺血前10 min给予3.5 μg/kg APN,余同I/R组。观察各组心律失常的发生情况;应用RT-PCR观察各组心室肌细胞 Cx43 基因表达;用免疫组织化学方法观察Cx43分布的变化;应用硫代巴比妥酸(TBA)法和黄嘌呤氧化酶法测各组动物血清中丙二醛(MDA)的含量和超氧化物歧化酶(SOD)的活性;用RT-PCR及Western blotting法分析内皮型一氧化氮合酶(eNOS)mRNA及蛋白的表达,用电镜观察各组心室肌超微结构的改变。结果: (1)I/R组与SM组比较,心律失常评分和血清MDA含量显著增高(P<0.01),SOD活性降低(P<0.01);心室肌Cx43表达明显减少,差异有统计学意义(P<0.01),Cx43分布紊乱,失去正常的规律性;心肌细胞超微结构有明显损伤;心室肌eNOS mRNA及蛋白的表达明显降低,差异有统计学意义(P<0.01)。(2)无论缺血前还是缺血后使用脂联素处理,与I/R组相比,心律失常评分显著降低(P<0.01);Cx43及eNOS表达增高(P<0.01),Cx43分布紊乱的程度减轻;心肌细胞超微结构损伤明显改善。结论: APN可能通过氧化应激调节Cx43的功能,从而发挥抗缺血/再灌注心律失常的作用。

Effects of adiponectin on expression of connexin 43 in rat myocardium during ischemia-reperfusion

AIM:To observe the effects of adiponectin(APN) on the expression of connexin 43(Cx43) in rat myocardium during ischemia-induced arrhythmias.METHODS:The SD rats were randomly divided into 4 groups(n = 12):sham operation group(SM group),ischemia and reperfusion group(I/R group),I/R + adiponectin(APN1 ) group: pre -ischemia with 3.5μg/kg of APN;I/R + APN2 group:post-ischemia with 3.5 p,g/kg of APN.The incidence of ventricular arrhythmias and ventricular arrhythmia score(VAS) were determined.The expression of Cx43 in the ischemic myocardium was studied by the techniques of immunohistochemistry and RT-PCR.The levels of malondialdehyde(MDA) and superoxide dismutase(SOD) were measured by the methods of xanthine oxidase and thiobarbituric acid.The expression of endothelial nitric oxide synthase(eNOS) at mRNA and protein levels was determined by RT-PCR and Western blotting, respectively.The morphological changes of the myocardial tissues were observed under electronic microscope.RESULTS: The VAS and concentration of MDA increased obviously and the activity of SOD was decreased in I/R group as compared with SM group(P <0.01).The expression of Cx43 was evidently decreased and the distribution of Cx43 in the myocardium was disturbed.The expression of eNOS at mRNA and protein levels was decreased in I/R group(P<0.05). The ultrastructure of ventricular myocardium was abnormal in I/R group.Compared with I/R group,APN obviously decreased the VAS caused by ischemia and reperfusion(P < 0.01) no matter the drug was given before or after ischemia. APN increased the activity of SOD,inhibited the MDA content in serum,and resulted in normal distribution of Cx43 and increased the expression of Cx43 and eNOS.Compared with I/R group,the changes of heart ultrastructure attenuated greatly in APN group,but didn’t recover to normal state.CONCLUSION:Adiponectin antagonizes the arrhythmias during myocardial ischemia and reperfusion via inhibiting oxidative stress and regulating Cx43.