离体和在体大鼠心脏缺血再灌过程自由基特性的ESR研究

STUDY ON THE CHARACTERISTICS OF FREE RADICALS PRODUCED IN ISCHEMIC/ REPERFUSED RAT MYOCARDIUM WITH ESR TECHNOLOGY IN VIVO AND IN VITRO

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。

The free radicals (FRs) concentration produced in ischemic / reperfused (I-R) rat myocardium was determined by ESR technology in vivo and in vitro. The results showed that the concentrations of FRs with a gvalue at 2.0015 increased after ligation of LAD for 10 min and reperfusion for 30s both in vivo and in vitro cell-free K-H solution perfusion model, being significantly higher than those in sham ligated control.It suggested that a large amount of FRs was generated during I-R and the source of FRs might not be circulating leucocytes. The results of experiment in vitro FRs generation systems demonstrated that vitamin C was an · OH andO2 radical scavenger and N-acetylcysteine (NAC) was an ·OH scavenger. Injection of these two agents 2 minutes before the ligation reduced the myocardial FRs to control levels. It seems that the major primary FRs generated in I-R myocardium were · OH and O2 radicals. The sensitivity of these FRs to microwave power and their characteristic g-value indicated that the major components of signals were produced by carbon-centered and peroxide organic radicals,which may be secondary products derived from primary oxygen FR reactions.The results suggest that inhibition or scavenging of primary oxygen FRs might play a beneficial role in the amelioration of I-R induced myocardial damage.