异氟烷预处理对心肌缺血再灌注损伤大鼠心肌p38丝裂原活化蛋白激酶水平的影响

Effects of isoflurane preconditioning on p38 MAPK in a rat model of myocardial ischemia-reperfusion

目的探讨异氟烷预处理对心肌缺血再灌注大鼠心肌p38丝裂原活化蛋白激酶(p38 mitogen-activatedprotein kinase,p38 MAPK)水平的影响。方法雄性Wistar大鼠90只,体重270～390 g。腹腔注射硫代仲丁巴比妥钠150 mg/kg麻醉后,阻断左冠状动脉前降支30 min,再灌注2 h,建立心肌缺血再灌注损伤模型。取60只大鼠,随机分为6组(n=10),于缺血前CON组静脉注射0.9%生理盐水;SB组经3 min静脉注射p38 MAPK抑制剂SB203580 1.5 mg/kg;DMSO组经3 min静脉注射SB203580溶剂DMSO 0.2 mL;ISO组吸入1.0 MAC异氟烷30 min后停止吸入15 min;SB+ISO组和ISO+SB组分别在吸入异氟烷前即刻和吸入异氟烷后即刻静脉注射SB203580 1.5 mg/kg。再灌注2 h后采用氯化硝基四氮唑蓝染色法测定心肌梗死面积。取剩余的30只大鼠,随机分为5组(n=6),CON组、SB组、ISO组、SB+ISO组和ISO+SB组所有处理同前。缺血前即刻、再灌注后2 h即刻取心肌标本,采用Western blot法测定p38 MAPK的表达水平。结果与CON组比较,SB组、ISO组、SB+ISO组和ISO+SB组心肌梗死面积降低(P<0.05)。再灌注后的CON组和ISO组p38 MAPK水平高于缺血前CON组(P<0.05)。结论异氟烷预处理和p38 MAPK抑制剂SB203580对心肌有保护作用,但p38 MAPK未参与异氟烷预处理减轻大鼠心肌缺血再灌注损伤的机制。

Objective To investigate the effects of isoflurane preconditioning on the expression of p38 mitogen-activated protein kinase（p38 MAPK） in myocardium in a rat model of myocardial ischemia-reperfusion（I/R）. Methods Ninety male Wistar rats weighing 270-390 g were anesthetized with intraperitoneal thiobutabarbital 150 mg/kg,tracheostomized and mechanically ventilated.I/R were produced by reversible occlusion of left anterior descending branch（LAD） of coronary artery for 30 min followed by 2-hour reperfusion.Then,sixty animals were randomly divided into 6 groups（n=10 for each）：（1） control group received intravenous normal saline（NS） before I/R;（2） SB group received SB203580（p38 MAPK inhibitor） 1.5 mg/kg iv before I/R;（3） DMSO group received DMSO（the SB203580 solvent） 0.2 mL before I/R;（4） ISO group inhaled 1.0 MAC isoflurane for 30 min followed by 15 min wash-out before I/R;（5） SB＋ISO group and（6） ISO＋SB group received SB 1.5 mg/kg before and after 30 min 1.0 MAC isoflurane inhalation.At the end of 2-hour reperfusion,the size of myocardial infarct was determined using triphenyl tetrazolium chloride staining.Another 30 animals were randomly divided into 5 groups（n=6 for each）： control group,SB group,ISO group,SB＋ISO group and ISO＋SB group.Before occlusion of LAD and at the end of 2-hour reperfusion,myocardial specimens were obtained for determination of expression of p38 MAPK protein in myocardium（Western blot）. Results SB group,ISO group,SB＋ISO group and ISO＋SB group significantly reduced infarct size.The expression of p38 MAPK protein was up-regulated in CON group and ISO group after 2-hour reperfusion as compared to the CON group before occlusion of LAD.Conclusions Isoflurane preconditioning and p38 MAPK inhibitor SB203580 can protect myocardium against I/R injury,but p38 MAPK may not be involved in the mechanism of isoflurane preconditioning.