诱导型一氧化氮合酶在衰老大鼠心肌对缺血再灌注损伤敏感性增加中的作用

The Effect of iNOS on Increased Susceptibility of Cardiac Ischemia/reprefusion Injury in AgedRat

目的探讨衰老大鼠心肌组织过氧亚硝基阴离子(ONOO-)的来源及其在衰老大鼠心肌对缺血再灌注损伤敏感性增加中的作用。方法选取雄性成年SD大鼠和衰老SD大鼠,随机分为3组,成年缺血再灌注组(缺血30 min,再灌注24 h)、衰老缺血再灌注组(缺血30 min,再灌注24 h),衰老缺血再灌注+1 400W组,缺血30 min,再灌注24 h,缺血前24 h及再灌注前25 h分别腹腔注射诱导型一氧化氮合酶(iNOS)的特异性阻断剂1 400W。采用Evans blue和TTC双染法检测心梗面积;用ELISA法检测心肌组织硝基酪氨酸(NT)含量;用Western-blot蛋白印迹法检测大鼠心肌组织中iNOS的蛋白表达水平。结果与成年缺血再灌注组相比,衰老缺血再灌注组心梗面积增大(P<0.05);心肌组织NT含量较成年缺血再灌注组明显增高(7.29±0.1 vs 4.61±0.1,P<0.05);iNOS表达增高(P<0.05);与衰老缺血再灌注组比较,衰老缺血再灌注+1 400W组NT含量减少(3.2±0.1 vs 7.29±0.1,P<0.05);心肌梗死面积减小。结论衰老大鼠对心肌缺血再灌注损伤的敏感性增加可能与衰老大鼠心脏中iNOS表达升高有关,催化生成大量NO进而生成毒性的ONOO-,从而损伤心肌。

Objective To observe the origin of ONOO-in aged heart and whether it was involved in increased susceptibility of aged heart to ischemia/reperfusion injury.Methods Male Sprague-Dawley young（6 months to 8 months） and aged rats（22 months to 24 months） were randomly divided into three groups：Young and aged myocardial ischemia/reperfusion（MI/R） group（ischemia 30 min and reperfusion 24 hours）,and aged MI/R group with specific inhibitor of iNOS,1 400W（2 mg/kg,IP given 24 hours before ischemia and 25 minutes before reperfusion）.The myocardial infarct size was determined by Evan＇s Blue and TTC staining.The protein expression of iNOS was determined by Western-blot,and the content of NT was determined by ELISA.Results Compared with young MI/R group（4.61±0.10）,the content of NT in aged ischemic-reperfusion heart was increased significantly（7.29±0.1,P0.05）,while the protein expression of iNOS and the myocardial infarct size was also increased markedly（P0.05）.Compared with aged MI/R group,both the protein expression of iNOS and myocardial infarct size were decreased significantly with 1 400 w（P0.05）,while the content of NT was also decreased in aged MI/R group with 1 400W（7.29±0.1 vs 3.2±0.1,P0.05）.Conclusion Increased expression of iNOS and subsequently toxic ONOO-production in aged ischemia-reperfusion heart were involved in increased susceptibility of aged heart to ischemia/reperfusion injury.