中文摘要：

目的 评价迷走神经电刺激后处理减轻大鼠心肌缺血再灌注损伤的适宜时机.方法 选择SPF级雄性SD大鼠120只,8周龄,体重290～ 320 g,采用随机数字表法,将其分为6组（n=20）：假手术组（S组）；缺血再灌注组（I/R组）结扎冠状动脉左前降支30 min,再灌注120 min；不同时机迷走神经电刺激后处理组（P1-4组）：于心肌缺血15 min（P1组）、再灌注即刻（P2组）、30 min（P3组）、60 min（P4组）时对右侧迷走神经实施电刺激（波宽1 ms、频率10 Hz、电压1～2V）,持续时间30 min,其余处理同I/R组.于缺血再灌注期间记录HR和SP,计算二者乘积（RPP）.于再灌注120 min时采集颈静脉血样,采用ELISA法检测血清cTnI、CK-MB、TNF-α、高迁移率族蛋白-1（HMGB-1）、细胞间粘附分子-1（ICAM-1）、IL-1、IL-6和IL-10的浓度；取心肌组织测定心肌梗死范围,采用ELISA法检测缺血区心肌TNF-α、HMGB-1、ICAM-1、IL-1、IL-6和IL-10的含量.于再灌注30 min内记录室性心律失常的发生情况,并评分.结果 与S组比较,I/R组和P1-4组心肌梗死范围增大,血清cTnI、CK-MB浓度升高,I/R组血清TNF-α、HMGB-1、ICAM-1、IL-1和IL-6浓度升高,P2-4组血清HMGB-1、ICAM-1、IL-1和IL-6浓度升高,TNF-α浓度降低,P1组血清IL-10浓度升高,TNF-α浓度降低（P＜0.05）,HMGB-1、ICAM-1、IL-1和IL-6浓度差异无统计学意义（P＞0.05）.与I/R组比较,P1-4组心肌梗死范围减小、血清cTnI、CK-MB、血清和心肌TNF-α、HMGB-1、ICAM-1、IL-1和IL-6水平降低,P1组心肌IL-10含量升高,RPP、室性心律失常的发生率和评分降低（P＜0.05）.与P1组比较,P2-4组RPP、室性心律失常的发生率和评分、血清HMGB-1、ICAM-1浓度升高,心肌ICAM-1含量升高,P3组心肌TNF-α、IL-1含量升高,P4组心肌梗死范围增大,血清cTnI、CK-MB、血清和心肌TNF-α、HMGB-1、ICAM-1、IL-1和IL-6水平升高,IL-10含量降低（P＜0.05）.结论 心肌缺血15 min时行迷走神经电?

英文摘要：

Objective To evaluate the optimum time of postconditioning with electric vagal stimulation on myocardial ischemia-reperfusion （I/R） injury in rats.Methods One hundred and twenty male Sprague-Dawley rats,aged 8 weeks,weighing 290-320 g,were randomly allocated into 6 groups （n =20 each）：sham operation group （S group）; I/R group; electric vagal stimulation postconditioning at 15 min of ischemia,the onset of reperfusion,and 30 and 60 min of reperfusion groups （P1-4 groups）.The myocardial I/R model was established by occlusion of left anterior descending branch of coronary artery for 30 min followed by a 120 min of reperfusion.In P1-4 groups,the right vagus nerve was stimulated for 30 min with continuous electric rectangular pulses （2 ms,10 Hz,1-2 V） starting from 15 min of myocardial ischemia and the other procedures were similar to those previously described in group I/R.During the I/R period,the heart rate （HR） and systolic pressure （SP） were recorded and the rate pressure product （RPP） was calculated.Venous blood samples were collected from the jugular vein at 120 min of reperfusion for determination of serum concentrations of cardiac troponin Ⅰ （cTnI）,creatine kinase MB （CK-MB）,tumor necrosis factor α （TNF-α）,high-mobility group box protein 1 （HMGB-1）,intercellular adhension molecule 1 （ICAM-1）,i nterleukin （IL）-1,IL-6 and IL-10 using ELISA.The animals were then sacrificed and myocardial infarct size was measured by Evans blue and TTC staining.The myocardial contents of TNF-α,HMGB1,ICAM-1,IL-1,IL-6 and IL-10 in ischemic regions were measured using ELISA.The development of ventricular arrhythmias at the initial 30 min of reperfusion was recorded.The severity of arrhythmias was quantified by a scoring system.Results Compared with S group,the myocardial infarct size and serum concentrations of cTnI and CK-MB in I/R and P1-4 groups,serum concentrations of TNF-α,HMGB-1,ICAM-1,IL-1 and IL-6 in I/R group,serum concentrations of HMGB-1,ICAM-1,IL-1 and IL-6 i