内源性抗氧化酶在异氟烷预处理离体大鼠心肌保护作用中的变化

Changes of endogenous antioxidant enzymes in cardioprotective effect of isoflurane preconditioning against ischemia/reperfusion injury in isolated rat hearts

目的观察不同浓度异氟烷预处理离体大鼠心肌的保护作用及其与内源性抗氧化酶变化的关系。方法建立大鼠离体心脏Langendorff灌流模型,随机分为6组(n=14):空白对照组(CON组)、1.44MAC异氟烷对照组(ISO组)、缺血/再灌注组(I/R组)、0.72MAC(I1组)、1.08MAC(I2组)和1.44MAC(I3组)异氟烷处理组。除CON组和ISO组外,其余各组大鼠心脏均缺血30min,再灌注60min。异氟烷预处理在心脏缺血前25min时进行,用不同浓度异氟烷充分饱和的K-H液预处理20min,冲洗5min。记录平衡末,缺血前即刻,再灌注30、60min时的心功能指标,测定再灌注末心肌组织中内源性抗氧化酶的活性,计算心肌梗死面积。并检测I2组大鼠心肌在平衡末,缺血前即刻,缺血后即刻及再灌30min组织中内源性抗氧化酶的活力。结果心肌缺血/再灌注使离体大鼠心脏的LVEDP明显升高,HR、LVDP、dp/dtmin及dp/dtmax明显降低(P<0.05)。与I/R组比较,再灌注末,I2组和I3组LVEDP和心肌梗死面积均明显降低,HR、dp/dtmin、dp/dtmax以及各抗氧化酶活性明显升高(P<0.05)。与平衡末相比,在缺血后即刻心肌组织各内源性抗氧化酶的活性明显降低;而在再灌注30和60min时,其活性较缺血后即刻升高(P<0.05),但仍未达到平衡末水平。结论异氟烷预处理可以增强内源性抗氧化酶的活性,明显改善心功能,并减少心肌梗死面积,对大鼠离体缺血/再灌注心肌有保护作用。

Aim To investigate the protective effect of different concentrations of isoflurane preconditioning in isolated rat hearts and the relationship between this effect with changes of endogenous antioxidant enzymes.Methods The isolated SD rat hearts perfused on Langendorff apparatus were randomly divided into 6 groups（n=14）：control group（CON）;1.44 MAC isoflurane control group（ISO）;ischemia-reperfusion group（I/R）;3 isoflurane preconditioning groups（I1,I2,I3）.All hearts were made globally ischemic for 30 min followed by 60 min reperfusion except CON and ISO.The hearts of ISO and I1,I2,I3 were perfused with K-H solution saturated with 0.72 MAC or 1.08 MAC or 1.44 MAC isoflurane respectively for 20 min followed by 5 min washout after equilibrium.The cardiac function variables were measured after equilibrium,immediately before ischemia,at the end of 30 min and 60 min reperfusion.The infarct size and activities of the endogenous antioxidant enzymes were measured at the end of reperfusion.And the activities of enzymes in I2 group were measured after equilibrium,immediately before ischemia,immediately after ischemia and at the end of 30 min reperfusion.Results Ischemia/reperfusion significantly increased LVEDP and decreased LVDP,dp/dtmax,dp/dtmin and HR（P〈0.05）.Compared with I/R at the end of reperfusion,LVEDP and the infarct size were significantly decreased but HR,dp/dtmax,dp/dtmin and activities of endogenous antioxidant enzymes were markedly increased in I2 and I3 groups（P〈0.05）.After ischemia immediately,the activities of enzymes were markedly lower than equilibrium.During reperfusion period,the activities of endogenous antioxidant enzymes were increased but still lower than equili brium.Conclusion Isoflurane preconditioning can enhance the activities of endogenous antioxidant enzymes,significantly improve cardiac function,reduce myocardial infarct size,and protect the isolated hearts against ischemia/reperfusion injury.