七氟醚对低温全心缺血-再灌注心律失常心肌组织Kir2.1蛋白表达的影响

目的观察七氟醚对低温全心缺血-再灌注心律失常心肌组织Kir2.1蛋白表达的影响。方法健康成年雄性SD大鼠,体重280~320 g,制备Langendorff离体心脏灌注模型24只,K-H液平衡灌流15 min后,随机分为三组:对照组(C组)、低温全心缺血-再灌注组(IR组)和七氟醚组(Sev组),每组8只。C组持续平衡灌流37℃K-H液105 min。IR组K-H液继续灌流15 min后,采用4℃Thomas液20 ml/kg使心脏停跳60 min,心脏周围用4℃的Thomas液进行保护,在心脏停跳30 min时追加注射4℃Thomas液10 ml/kg,在心脏停跳60 min时再灌注K-H液30 min。Sev组灌注液为饱含1 MAC七氟醚的K-H液,其余同IR组。观察并记录再灌注期间心律失常发生情况、心脏复跳时间和心律失常持续时间;记录平衡灌注15 min(T0)、继续灌注15 min/平衡30 min(T1)、再灌注15 min/平衡105 min(T2)、再灌注30 min/平衡120 min(T3)的左心室前壁外膜层和内膜层心肌单相动作电位(MAP),计算50%和90%单相动作电位时程(MAPD50、MAPD90);Western blot法和免疫组织化学法检测心肌组织Kir2.1蛋白相对含量和分布。结果灌注心脏复跳时IR组有6例发生心律失常,2 min内有1例恢复正常节律;Sev组有2例发生心律失常,2 min内有均恢复正常节律;IR组心脏复跳时间、心律失常持续时间明显长于Sev组(P<0.05);与T0和T1时比较,T2-T3时IR组外膜层和内膜层MAPD90明显延长(P<0.05);Sev组外膜层MAPD90明显延长(P<0.05)。T2-T3时Sev组和IR组外膜层和内膜层MAPD90明显长于C组(P<0.05),Sev组内膜层和外膜层MAPD90明显短于IR组(P<0.05)。IR组Kir2.1蛋白相对含量明显低于C组(P<0.05),Sev组Kir2.1蛋白相对含量明显高于IR组(P<0.05);C组Kir2.1蛋白呈强阳性表达,且具有规则的分布;IR组Kir2.1蛋白的表达点状分散分布且无规律;Sev组Kir2.1蛋白呈强阳性表达,且具有规则的分布。结论七氟醚降低低温全心缺血-再灌注心律失常的发生,其分子机制可能与Kir2.1蛋白的表达与分布改善有关。

Effect of sevoflurane on the expression of Kir2.1 protein in myocardium with hypothermic global ischemia-reperfusion arrhythmia

Objective To observe the effect of sevoflurane on the expression of Kir2.1 protein in myocardial tissue of arrhythmia induced by hypothermic global ischemia-reperfusion.Methods Twenty-four healthy adult male SD rats,weighing 280-320 g,were successfully prepared into Langendorff isolated heart perfusion model.After 15 min of K-H liquid equilibrium perfusion,they were randomly divided into three groups(n=8):control group(group C),hypothermic global ischemia-reperfusion group(group IR)and sevoflurane group(group Sev).In group C,K-H fluid was continuously perfused for 105 min.In group IR,after 15 min of continuous perfusion of K-H solution,Thomas solution(4℃,20 ml/kg)was injected to make the heart stop beating.When the heart stopped beating for 30 minutes,Thomas solution(4℃,10 ml/kg)was added.When the heart stopped beating for 60 min,K-H solution was reperfused for 30 min.In group Sev,K-H fluid contained 1.0 MAC sevoflurane and other procedures were the same as that in group IR.The occurence of arrhythmia were recorded during the period of reperfusion.MAP S including time course(MAPD 50 and MAPD 90)of endocardium and epicardium was recorded at the time of balanced perfusion for 15 min(T 0),continuous perfusion for 15 min(T 1),reperfusion for 15 min/continuous perfusion for 105 min(T 2)and reperfusion for 30 min/continuous perfusion for 120 min(T 3).The expression and distribution of Kir2.1 protein in myocardium were detected by immunoblotting and immunohistochemistry.Results Arrhythmias occurred in 6 cases in group IR and returned to normal rhythm in 1 case within 2 min,and that occurred in 2 cases in group Sev and returned to normal rhythm in 2 min.The development of arrhythmia and time for restoration of spontaneous heart beat in group IR were significantly longer than those in group Sev(P<0.05);Compared with T 0-T 1,MAPD 90 in the outer and inner membrane of group IR was significantly longer(P<0.05),and MAPD 90 in the outer membrane of group Sev was significantly longer(P<0.05).At T 2-T 3,MAPD 90 of outer and inner membrane in group Sev and group IR were significantly longer than that in group C(P<0.05),and MAPD 90 of inner and outer membrane in group Sev were significantly shorter than that in group IR(P<0.05).The relative content of Kir2.1 protein in group IR was significantly lower than that in group C(P<0.05),and the relative content of Kir2.1 protein in group Sev was significantly higher than that in group IR(P<0.05).Kir2.1 protein in group C showed strong positive expression and regular distribution.Kir2.1 protein in group IR was scattered and irregular.Kir2.1 protein in group Sev showed strong positive expression and regular distribution.Conclusion Sevoflurane can reduce the occurrence of hypothermia ischemia-reperfusion arrhythmia,and its molecular mechanism may be related to the changes of Kir2.1 protein expression and distribution.