远端肢体缺血预处理对失血性休克液体复苏大鼠心肌损伤的保护作用研究

Effect of remote ischemic pre-conditioning on myocardial ischemic injury in a hemorrhagic shockreperfusion rat model

目的利用心脏超声、心电图以及心肌损伤标志物综合评价远端肢体缺血预处理对失血性休克液体复苏大鼠心肌损伤的保护作用。方法成年健康雄性SD大鼠（300~350 g）36只,随机分为3组（n=12）：空白对照组（C组）、失血性休克复苏组（SR组）和远端肢体缺血预处理组（RIPC组）。经股动脉持续1 h放出全身血容量的50%血液,1 h后由股静脉30 min回输全部自体血,建立失血性休克和复苏模型。RIPC组于放血前40 min采用止血带阻断双侧后肢血流5 min,松开5min,反复4次,行远端肢体缺血预处理。于基础状态（BL）、放血结束即刻（S1）、回输自体血液前（S2）、回输结束即刻（R1）、回输后1 h（PR1h）以及2 h（PR2h）,记录心电图以及平均动脉压（MAP）,采用心脏彩色多普勒超声测量心输出量、LVEF、左心室短轴缩短率（FS）以及左心室心肌活动指数（Tei Index）,利用免疫化学发光仪检测动脉血在BL、S2、PR2h时间点的心肌肌钙蛋白I（c TnⅠ）浓度,观察大鼠复苏后72 h存活情况。结果与C组相比,SR组在S1至PR2h时,RIPC组在S1和S2时MAP、心输出量、LVEF降低,Tei Index升高（P〈0.01）;和SR组比较,RIPC组在复苏开始后的MAP、心输出量、LVEF升高,Tei Index降低（P〈0.01）;在S1至PR2h,SR组与RIPC组ST段偏移程度以及c Tn I浓度比C组增加（P〈0.01）;然而,RIPC组的ST段偏移程度较SR组轻（P〈0.01）,复苏存活率较高（P〈0.01）。结论远端肢体缺血预处理显著减轻失血性休克液体复苏后大鼠的心肌缺血再灌注损伤,明显改善了生存预后。

Objective Cardiac ultrasound,electrocardiogram and measurement of myocardial injury markers were performed to comprehensively investigate the effect of remote ischemic pre-conditioning（ RIPC）upon myocardial ischemic injury in a hemorrhagic shock-reperfusion rat model. Methods Thirty six male adult Sprague-Dawley rats,weighing 300-350 g,were randomly divided into the sham control（ C）,hemorrhagic shock-reperfusion（ SR） and RIPC groups（ n = 12 for each group）. Hemorrhagic shock-reperfusion rat models were established by 60-min bleeding（ 50% of total blood volume） via femoral artery followed by 30-min reperfusion via femoral vein at 1 h later. In the RIPC group,bilateral hind limbs were clamped at 40 min before hemorrhage. The procedure involved four cycles of 5 min of ischemia followed by 5 min of reperfusion. Electrocardiographic tracing and mean arterial pressure（ MAP） were continuously recorded for at baseline（ BL）,immediately after bleeding（ S1）,before reperfusion（ S2） and after reperfusion（ R1） and 1 h after reperfusion（ PR1h） and 2 h after reperfusion（ PR2 h,respectively. Cardiac output（ CO）,left ventricular ejection fraction（ LVEF）,fractional shortening（ FS） and Tei Index were measured by electrocardiogram. The concentration of cardiac troponin I（ c Tn I） in the arterial blood was measured at BL,S2 and PR2 h. The survival of animals was observed at 72 after resuscitation. Results Compared with the C group,the MAP,CO and FS in the SR group at S1-PR2 h,and in the RIPC group at S1-S2 were significantly decreased whereas Tei Index was considerably elevated（ all P〈0. 01）. Compared with the SR group,the MAP,CO and FS were significantly decreased whereas Tei Index was considerably increased in the RIPC group after resuscitation（ all P〈0. 01）. From S1 to PR2 h,ST-segment depression and c Tn I concentration in the SR and RIPC groups were significantly higher than those in the C group（ all P〈0. 01）,whereas the degree of increase in the RIPC group was significantly less than that in the SR group（ P〈0. 01）. The survival rate after resuscitation in the RIPC group was also significantly higher compared with that in the SR group（ P〈0. 01）. Conclusion RIPC effectively alleviates myocardial ischemic injury and significantly enhances prognosis outcomes in a hemorrhagic shock-reperfusion rat model.