右美托咪定预处理对猪心肌缺血再灌注损伤的影响

Effect of dexmedetomidine preconditioning on myocardial ischemia-reperfusion injury in pigs

目的 观察右美托咪定预处理对猪心肌缺血再灌注损伤的保护作用.方法 小型猪20头,体质量25 - 35 kg,雌雄不限.随机分为两组：右美托咪定预处理组（Dex组）、对照组（C组）,每组10头.肌肉注射氯胺酮及咪达唑仑麻醉后,行气管切开,机械控制通气,七氟烷维持麻醉.Dex组同时静脉注射负荷量右美托咪定0.5μg/kg,随后持续泵入0.5μg/（kg·h）维持至冠状动脉阻断前,对照组注射等容量生理盐水.开胸暴露心脏后,于冠状动脉前降支中下1/3处阻断30 min,再灌注时间为60 min.阻断前后不同时间点记录平均动脉压（MAP）、心率（HR）、中心静脉压（CVP）.分别于开胸前、阻断后30 min、再灌注后30、60 min抽取颈内静脉血4ml,酶联免疫吸附法测定猪血清心肌肌钙蛋白I （cTnI）、肌酸激酶心肌型同工酶（CK-MB）浓度.心肌缺血再灌注20 min进行心律失常评分.再灌注结束后,重新阻断冠状动脉前降支,伊文氏蓝染色,计算心肌梗死面积（IS％）.结果 再灌注30 min和再灌注60 min时C组的CK-MB及cTnI高于D组（P＜0.05）.C组和D组再灌注20 min心律失常评分分别为（3.300 ±0.675）和（2.000 ±0.677）分,组间比较差异有统计学意义（P＜0.05）.C组的IS％（42.4％）高于D组（23.5％,P＜0.05）.结论 Dex预处理可减轻猪心肌缺血再灌注损伤,具有心肌保护作用.

Objective To investigate the effects of dexmedetomidine preconditioning on myocardial ischemia-reperfusion injury in pigs.Methods Twenty healthy pigs of both sexes,weighing 25-35 kg,were randomly divided into two groups （n =10 each）：control group （group C）,and dexmedetomidine group （Dex group）.Ketamine 10 mg/kg combined with midazolam 0.1 mg/kg were injected intramuscularly,and the trachea was intubated after the incision of trachea followed by mechanical ventilation.Anesthesia was maintained with sevoflurane （1.5％-2.0％）.A loading dose of dexmedetomidine 0.5 μg/kg was injected intravenously over 10 min after intubation followed by infusion at 0.5 μg/（kg·h） until the occlusion of descending coronary artery.After the infusion of study drugs,the hearts were subject to 30 min of regional ischemia followed by 60 min of reperfusion.Mean arterial pressure （MAP）,heart rate （HR）,and central venous pressure （CVP） were recorded at the time point of pre-ischemia,10 and 30 min after ischemia,and 10,30 and 60 min after reperfusion.The blood samples from the internal jugular vein were collected,cTnI and CK-MB were determined by enzyme linked immunosorbent assay （ELISA）.The arrhythmia was scored 20 min after the reperfusion.The descending coronary artery was reoccluded after the end of reperfusion,and the left ventricles which were not blocked were stained with Evans blue.The left ventricles were sliced from base to the tip into 10-mm slices.The infarct size （IS％） was calculated.Results CK-MB and cTnI were higher in group C than in Dex group at re-perfusion 30 min and 60 min （P ＜ 0.05）.The scores of the arrhythmia were （3.300 ±0.675） in group C,higer than in Dex group （2.000 ±0.677） （P ＜ 0.05）.IS％ in group C was 42.4％,higher than in Dex group （23.5％,P ＜0.05）.Conclusion Dexmedetomidine preconditioning can reduce myocardial ischemia-reperfusion injury in pigs.