诱导型一氧化氮合酶在舒芬太尼预处理减轻大鼠心肌缺血再灌注损伤中的作用

Role of inducible nitric oxide synthase in reduction of myocardial ischemia-reperfusion injury by sufentanil preconditioning in rats

目的 探讨诱导型一氧化氮合酶（iNOS）在舒芬太尼预处理减轻大鼠心肌缺血再灌注损伤中的作用.方法 成年雄性SD大鼠30只,体重250～330 g,采用随机数字表法,将大鼠随机分为5组（n=6）：假手术组（S组）只穿线,不结扎;心肌缺血再灌注组（I/R组）采用结扎左冠状动脉前降支30min,再灌注120 min的方法制备大鼠心肌缺血再灌注损伤模型;舒芬太尼预处理组（SF组）缺血前24 h经尾静脉输注舒芬太尼120μg/kg,输注时间30 min;舒芬太尼预处理＋iNOS特异性抑制剂S-甲硫脲组（SF＋SMT组）缺血前24 h经尾静脉输注舒芬太尼120μg/kg,缺血前10 min静脉注射SMT 10 mg/kg;SMT组缺血前10 min静脉注射SMT 10 mg/kg.于缺血前30 min、缺血30 min、再灌注120 min时记录HR和MAP,计算RPP（SP× HR）.于再灌注120 min时取颈动脉血样2 ml,测定血浆NO浓度,随后取心脏制病理切片,测定缺血危险区（AAR）和梗死区（IS）体积,计算心肌梗死体积（IS/AAR）,测定心肌iNOS表达.结果 与S组比较,余4组再灌注120 min时MAP和RPP降低,IS/AAR升高,I/R组和SMT组缺血30 min时MAP和RPP降低（P＜0.05）;与I/R组比较,SF组、SF＋SMT组和SMT组HR、MAP和RPP差异无统计学意义,SF＋SMT组和SMT组IS/AAR和血浆NO浓度差异无统计学意义（P＞0.05）,SF组IS/AAR降低,血浆NO浓度和心肌iNOS表达升高（P＜0.05）.结论 iNOS参与了舒芬太尼预处理减轻大鼠心肌缺血再灌注损伤的过程.

Objective To investigate the role of inducible nitric oxide synthase （iNOS） in reduction of myocardial ischemia-reperfusion （I/R） injury by sufentanil preconditioning in rats. Methods Thirty adult male SD rats, weighing 250-330 g, were randomly divided into 5 groups （ n =6 each）： sham operation group （group S）,I/R group, sufentanil preconditioning group （group SF）, sufentanil preconditioning ＋ a specific inhibitor of iNOS S-methyl thiourea （SMT） group （group SF＋ SMT） and S-methyl thiourea group （group SMT）. In I/R,SF,SF＋SMT and SMT groups, myocardial I/R was produced by occlusion of left anterior descending coronary artery for 30 min followed by 120 min reperfusion. Group SF received 30 min infusion of sufentanil 120 μg/kg via caudal vein 24 h before ischemia. Group SF ＋ SMT received infusion of sufentanil 120 μg/kg via caudal vein 24 h before ischemia and then SMT 10 mg/kg was injected 10 min before ischemia. In group SMT, SMT 10 mg/kg was injected 10min before ischemia. MAP and HR were recorded at 30 min before ischemia, at 30 min of ischemia and at the end of reperfusion. The rate-pressure product （RPP） was calculated. Arterial blood samples were obtained immediately at the end of reperfusion to determine the plasma concentration of NO. Then the animals were sacrificed and myo cardial tissues were obtained to determine the area at risk （AAR）, infarct size （IS） and iNOS expression. IS/AAR was calculated. Results Compared with group S, MAP and RPP were significantly decreased, while IS/AAR was significantly increased at 120 min of reperfusion in the other four groups, and MAP and RPP were significantly decreased at 30 min of ischemia in I/R and SMT groups （ P 〈 0.05）. Compared with group I/R, no significant change was found in HR, MAP and RPP in SF, SF ＋ SMT and SMT groups, and in IS/AAR and plasma NO concentrations in SF ＋ SMT and SMT groups （ P 〉 0.05）, but IS/AAR was significantly decreased, and the plasma NO concentration and iNOS expression were significantly increased in group SF （ P 〈 0. 05）. Conclusion iNOS is involved in reduction of myocardial I/R injury by sufentanil preconditioning in rats.