体外反搏对心肌梗死犬一氧化氮和一氧化氮合酶的影响

Effects of External Counterpulsation on the Nitric Oxide and Nitric Oxide Synthase in Myocardial Infarction Canines

目的:探讨体外反搏对心肌梗死犬一氧化氮(NO)和一氧化氮合酶(NOS)的作用。方法:15只健康杂种犬随机分为对照组、缺血组和反搏组3组,采用开胸结扎冠状动脉左前降支的方法建立心肌缺血模型,用改良硝酸还原酶法测定心肌缺血前后血清NO含量、以及心肌组织的NO含量和NOS比活性,并用电镜观察犬心肌组织超微结构的损伤程度。结果:在冠状动脉结扎前和结扎后60min,3组犬血清NO含量均无差异(P>0.05);结扎后120min和180min时,反搏组犬血清NO含量明显高于缺血组(P<0.05)。正常组和反搏组犬心肌组织NO含量和NOS比活性均大于缺血组(P<0.05)。电镜显示反搏组犬心肌组织的线粒体、肌节和血管内皮细胞损伤较缺血组轻。结论:体外反搏对心肌缺血性损伤有保护作用,其中NO和NOS可能起重要作用。

Objective: To investigate the effects of external counterpulsation (ECP) on the nitric oxide (NO) and nitric oxide synthase (NOS) in myocardial infarction canines. Methods: Fifteen health dogs were randomly divided into three groups ( ischemia group, ECP group and controls). The myocardial ischemic model was set up by ligating of the left anterior descending artery(LAD). Before and after the ligation of the LAD, the serum NO concentrations and myocardium NO levels and NOS specific activity were determined by modified nitrate reductase method. At the same time the myocardium was taken for electromicroscopy. Results: Before and 60 min after the ligating of the LAD, the serum NO levels had no significant difference among this three groups(P>0.05); but 120 and 180 min later, the serum NO concentration in ECP groups were higher than those in ischemic groups (P<0.05). The NO levels and NOS specific activity in myocardium of ischemic dogs were lower than those in controls and ECP group (P<0.05). Electromicroscopically, the injuries of the myocardium including sarcomeres, mitochondria and microvascular endothelial cells were less obvious in ECP group than those in the ischemia group. Conclusions: ECP treatment could effectively protect the myocardium against ischemic injury, in which NO and NOS may exert an important role.