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用ESR技术直接测定离体和在体大鼠心肌组织缺血再灌(I-R)过程中的自由基浓度。结果表明,在用无细胞K-H液灌流的离体I-R模型和在体I-R过程中,大鼠心脏结扎LAD10min再灌30s心肌组织中g=2.0015的自由基浓度均显著高于假结扎对照组。提示心脏I-R过程有大量自由基生成,且其主要来源不是白细胞。体外自由基生成系统试验结果表明,Vit C可清除O_2~+和·OH,N-乙酰半胱氨酸(NAC)只对·OH有一定清除作用。在体结扎LAD前2min静脉注射Vit C或NAC(150mg/kg)可使再灌后心肌内短时间产生的自由基浓度降至接近假结扎组水平,说明心脏I-R过程产生的原初自由基可能以·OH和O_2~+为主。测定心肌组织自由基信号对微波功率敏感性及信号g值特性表明了I-R过程中显著变化的信号成分主要来自碳中心有机自由基及有机过氧化自由基。它们可能是初级活性氧自由基反应的次级产物。抑制或清除初级活性氧自由基可能成为改善心脏I-R损伤的途径之一。
ESR technique was used to directly determine the concentration of free radicals during ischemia-reperfusion (I-R) in vitro and in vivo. The results showed that the free radical concentration of g = 2.0015 in myocardium was significantly higher than that of the sham-operated control group in the I-R perfusion and the I-R in vivo. Suggesting that the heart I-R process has a lot of free radicals, and its main source is not white blood cells. The results of in vitro free radical generation system showed that Vit C could scavenge O 2 ~ + and · OH, N-acetylcysteine (NAC) only scavenged · OH effectively. Intravenous injection of Vit C or NAC (150 mg / kg) 2 min prior to ligation of LAD in vivo results in a reduction of free radicals produced in the myocardium within a short period of time after reperfusion to levels near the level of the sham-ligation group, indicating that primary free radicals produced by cardiac IR processes may · OH and O_2 ~ + dominated. Determination of myocardial tissue free radical signal sensitivity to microwave power and signal g value characteristics showed that significant changes in the I-R signal components mainly from the carbon centers of organic free radicals and organic peroxidation free radicals. They may be secondary products of the primary reactive oxygen radical reaction. Inhibition or elimination of primary reactive oxygen species may be one of the ways to improve cardiac I-R injury.