心肌缺血-再灌注损伤大鼠心电图变化机制的研究

Study on mechanism of ECG change during myocardial ischemia-reperfusion process

[目的]探讨大鼠心肌缺血再灌注损伤过程中,氧自由基及心肌细胞凋亡与缺血再灌注性心律失常的关系。[方法]建立大鼠心肌缺血-再灌注模型,对比缺血期与再灌注期的心律失常发生率及平均持续时间、ST段改变、心肌丙二醛(malondialdehyde,MDA)含量及超氧化物歧化酶(superoxide dismutase,SOD)活力、心肌细胞凋亡情况。[结果]缺血期房室传导阻滞、室性早搏及室速的发生率分别为7.5%、15%及10%;再灌注后分别为30%、67.5%及32.5%,与缺血期相比,再灌注后上述指标均明显增高。室速的平均发作时间由缺血期的(40±14)s上升到(495±103)s(P<0.01);再灌注后室颤平均持续时间为(198±22)s。再灌注后心肌MDA含量高于缺血组(P<0.01),且有逐渐递增趋势;心肌SOD活力较缺血组降低(P<0.01),再灌注120 min后下降趋缓。再灌注组心肌细胞凋亡明显高于缺血组(P<0.05)。缺血再灌注损伤过程中,心律失常发生率与SOD活力变化呈负相关,与MDA值变化及心肌细胞凋亡变化均呈正相关。[结论]氧自由基及心肌细胞凋亡很可能是造成心肌缺血再灌注后心律失常的重要因素。

[Objective]To investigate the relationship between oxygen free radicals and myocardial apoptosis and arrhythmia during myocardial ischemia-reperfusion injuries.[Methods]Duplicated myocardial ischemia-reperfusion models of rats,and analyzed incidence rate and duration of arrhythmias,changes of ST segment,malondialdehyde（MDA） value,the activity of superoxide dismutase（SOD） and the state of myocardial apoptosis between ischemic and reperfusion process.[Results]The incidences of atrioventricular block,ventricular premature beat and ventricular tachycardia were 7.5%,15% and 10% respectively.After reperfusion,the above indicators increased to 30%,67.5% and 32.5% respectively.The duration of the ventricular tachycardia increased form（40±14） s to（495±103） s after reperfusion.In reperfusion the duration of ventricle fibrillation was（198±22） s.The content of MDA in the reperfusion group is more than that in ischemia group（P〈0.01）,and revealed the increasing trend.At the same time,the activity of SOD decreased during reperfusion.After 120 min reperfusion,the descending speed became slower.Myocardial apoptosis is obviously increased in the reperfusion group.During MIRI,the variations of arrhythmia had positive correlation with SOD change,and negative correlation with MDA and apoptosis changes.[Conclusion]The oxygen free radicals and myocardial apoptosis may be the important factors inducing arrhythmias inreperfusion.