缺血预处理对大鼠缺血再灌注心肌HIF-1α和HO-1的影响

Effect of ischemic preconditioning on HIF-1α and HO-1 in myocardium after myocardial ischemia-reperfusion injury in rats

目的探讨缺血预处理对大鼠缺血再灌注心肌低氧诱导因子1α（HIF-1α）和血红素加氧酶1（HO-1）的影响。方法健康雄性SD大鼠48只，体重220～280g，随机分为4组（n=12）：假手术组（S组）、缺血再灌注组（IR组）、缺血预处理＋缺血再灌注组（IP组）和缺血预处理＋缺血再灌注＋HO-1抑制剂组（HI组）。采用结扎左冠状动脉前降支30min再灌注120min的方法建立心肌缺血再灌注模型。S组仅在冠状动脉下穿线；IP组于缺血前采用结扎，放松左冠状动脉前降支各5min，重复3次的方法行缺血预处理；HI组于缺血预处理前1d腹腔注射锌原卟啉Ⅸ10mg／kg，其余同IP组。于再灌注结束时测定心肌HIF-1α、HO-1的mRNA和蛋白表达、HO-1活性、SOD活性及MDA含量，计算心肌梗死面积，取动脉血样测定血清TNF-α和IL-6的浓度。结果与S组比较，IR组、IP组和HI组心肌SOD活性降低，MDA含量升高，血清TNF-α和IL-6的浓度升高（P〈0．01）；与IR组比较，IP组心肌SOD活性升高，MDA含量降低，血清TNF-α和IL-6浓度降低，心肌HIF-1α和HO-1的mRNA和蛋白表达上调，HO-1活性升高，心肌梗死面积减小（P〈0．01）；与IP组比较，HI组心肌SOD活性降低，MDA含量升高，血清TNF-α和IL-6浓度升高，心肌HO-1的mRNA和蛋白表达下调，HO-1活性降低，心肌梗死面积增加（P〈0．05或0．01），心肌HIF-1α的mRNA和蛋白表达差异无统计学意义（P〉0．05）。结论缺血预处理减轻大鼠心肌缺血再灌注损伤的机制与HIF-1α诱导HO-1活性增强有关。

Objective To investigate the effect of ischemic preconditioning （IP） on hypoxia inducible factor-1α （HIF-1α） and heme oxygenase-1 （HO-1） in myocardium after myocardial ischemia-reperfusion （I/R） injury in rats and the mechanism. Methods Forty-eight male SD rats weighing 220-280 g were randomly divided into 4 groups （n = 12 each）： group A sham operation; group B I/R; group C IP ＋ I/R and group D IP ＋ IR ＋ HO-1 inhibitor. The animals were anesthetized with intraperitoneal 20% urethane 1 g/kg, tracheostomized and mechanically ventilated. Myocardial ischemia was induced by 30 min occlusion of left anterior descending branch （LAD） of coronary artery followed by 120 min reperfusion. Ischemic preconditioning was induced by 3 episodes of 5 min occlusion of LAD at 5 rain intervals before myocardial ischemia. Group D received HO-1 inhibitor ZnPP Ⅸ 10 mg/kg one day before IP. At the end of 120 min reperfusion the infarct size was measured, the expression of HIF-1α and HO-1 mRNA and protein, SOD and HO-1 activities and MDA content in myocardium and serum TNF-α and IL-6 concentrations were determined. Results Compared with sham operation group, I/R significantly increased MDA content in myocardium and serum TNF-α and IL-6 concentrations and decreased SOD activity in myocardium. Compared with I/R group, IP significandy decreased infarct size, increased HIF-1α and HO-1 mRNA and protein expression and HO-1 activity further and decreased serum TNF-α and IL-6 concentrations and myocardial MDA content in group C. In group D ZnPP Ⅸ pretreatment greatly increased infarct size which was significantly larger than that in group I/R and group IP ＋ I/R. Conclusion IP can protect against myocardial I/R injury. Increase in HO-1 activity induced by HIP-1α may be involved in the underlying mechanism.