Role of oxygen free radicals in reperfusion myocardial injury

为了确定再灌注缺血心肌中氧自由基（氧自由基）生成与心肌损伤进展之间的关系，我们在犬冠状动脉闭塞（90分钟）-再灌注模型中测量了缺血心肌中氧自由基生成和扩展梗死面积。我们用电子顺磁共振（EPR）自旋捕集技术（5，5 ′-二甲基-1-吡咯啉-n-氧化物，DMPO）检测了经穿刺活检的快速冷冻心肌样品中的氧自由基。正常心肌再灌注前后未见DMPO加合物的产生。在再灌注心肌中，检测到超氧阴离子（DMPO-OOH）和羟自由基（DMPO-OH）的EPR信号，DMPO-OOH和DMPO-OH的峰值分别出现在再灌注后1h和3 h。这些DMPO加合物在再灌注早期（15秒）也被检测到，但浓度 关于我们 在实验过程中用重组人超氧化物歧化酶（2.5mg/kg/h）和过氧化氢酶（2.5mg/kg/h）处理可消除DLIPO-OOH的形成，但对DMPO-OH的形成几乎没有影响。闭塞90分钟时，通过使用伊文思蓝染料和氯化三苯基四氮唑的双重染色方法定量的脑梗死面积（梗死风险区百分比）为18.3 - <plus-minus>4.8%（平均<plus-minus>SEM）。再灌注后，梗死面积增加到43.6 - <plus-minus>7.2%，在5小时的再灌注。这些结果表明，在再灌注后期（1-3小时），缺血心肌组织中持续产生更大幅度的氧自由基，这与心肌梗死的进展有关。氧自由基和进行性梗死的同时出现可能支持氧自由基的连锁反应有助于缺血后心肌细胞损伤的传播的观点。

To define the relationship between oxygen-derived free radical (oxy-radical) generation in the reperfused ischemic myocardium and the progression of myocardial damage, we measured oxy-radical generation in the ischemic myocardium and the propagating infarct size in a canine coronary occlusion (90 minutes)-reperfusion model. We used electron paramagnetic resonance (EPR) spin trapping techniques (5,5'-dimethyl-l-pyrroline-n-oxide, DMPO) to detect oxy-radicals in the rapidly frozen myocardial samples taken by needle biopsy. There was no detectable generation of DMPO adducts in the normal myocardium before and after reperfusion. In the reperfused ischemic myocardium, EPR signals of DMPO-OOH (superoxide anion) and DMPO-OH (hydroxyl radical) were detected, with peak concentrations at 1 hour after reperfusion for DMPO-OOH and at 3 hours after reperfusion for DMPO-OH, respectively. These DMPO adducts were also detected during the early phase (15 seconds) of reperfusion, but the concentrations … More of these signals were much less than those during the late phase of reperfusion.Treatment with human recombinant superoxide dismutase (2.5 mg/kg/hour) and catalase (2.5 mg/kg/hour) during the course of the experiments abolished DLIPO-OOH formation but had little effect on DMPO-OH formation. Infarct size (percent of risk area infarcted), quantified by a dual staining method using Evans blue dye and triphenyltetrazolium chloride, was 18.3 <plus-minus> 4.8% (mean <plus-minus> SEM) at 90 minutes of occlusion. After reperfusion, infarct size increased to 43.6 <plus-minus> 7.2% at 5 hours of reperfusion. These results indicate that a greater magnitude of oxy-radical generation was sustained in the ischemic myocardial tissue during the late phase (1-3 hours) of reperfusion, associated with the progression of myocardial infarction. The concurrent appearance of oxy-radicals and progressive infarction may support the view that a chain reaction of oxy-radicals contributes to the propagation of myocardial cell damage in the postischemic Less