摘要：
目的 观察不同浓度七氟醚对大鼠离体心脏缺血-再灌注时心肌单相动作电位(MAP)的影响.方法 健康成年雄性 SD大鼠 32 只,体重 280~320 g,成功制备 langendorff离体心脏灌注模型,K-H 液平衡灌注 1 5 min后,随机分为四组,每组 8 只:缺血-再灌注组(IR组):K-H 液继续灌注 15 min后停止,注射Thomas液(4°C,20 ml/kg)使心脏停搏60 min,心脏周围用低温(4°C) Thomas液保护,30 min时半量复灌Thomas液(4°C,10 ml/kg),60 min时再灌注K-H 液 30 min;0.5 MAC七氟醚组(Sev0.5 组):K-H 液为含饱和 0.5 MAC七氟醚液体,余同 IR 组;1.0 MAC 七氟醚组(Sev1.0 组):K-H 液为含饱和 1.0 MAC 七氟醚液体,余同 IR 组;2.0 MAC 七氟醚组(Sev2.0 组):K-H 液为含饱和2.0 MAC七氟醚液体,余同IR组.记录平衡灌注1 5 min(T0)、继续灌注 15 min(T1)、再灌注 15 min(T2)、再灌注 30 min(T3)的 HR 及左心室前壁外膜层、中层和内膜层心肌 MAP,计算MAP复极50%及90%的时程(MAPD50、MAPD90).并记录心律失常发生情况.结果 与T0和T1时比较,T2、T3时IR组、Sev1.0 组、Sev2.0 组 HR明显减慢(P<0.05);与IR组比较,T2、T3时Sev0.5 组、Sev1.0 组HR明显增快,Sev2.0 组HR明显减慢(P<0.05).与IR组比较,T3时 Sev0.5 组 MAPD50,Sev0.5 组、Sev1.0 组、Sev2.0 组 MAPD90明显缩短(P<0.05).心脏复跳时 IR组有 6 例,Sev0.5 组有 1 例,Sev1.0 组有 2 例,Sev2.0 组有 1 例发生心律失常,与 IR组比较,Sev0.5 组、Sev1.0 组和 Sev2.0 组心律失常发生率明显降低(P<0.05).结论 不同浓度七氟醚均可缩短缺血-再灌注心肌单相动作电位 MAPD90,且这一作用在 0.5~2.0 MAC 的七氟醚浓度范围内无剂量依赖性,这可能是其减少缺血-再灌注心律失常发生风险的机制.%Objective To study the effects of different concentrations of sevoflurane on monophasic action potentials (MAPs)of three-layer myocardium of ischemia reperfusion in isolated rat hearts.Methods Thirty-two healthy SD male rats,weighing 280-320 g,were randomly divided into four groups after successful preparation of langendorff isolated heart perfusion model and 1 5 min perfusion and balance of K-H fluid.In the ischemia-reperfusion group(group IR),K-H fluid perfusion was stopped and balanced for 15 min and cardiac arrest was induced for 60 min with the injection of Thomas solution (4°C,20 ml/kg)while the heart was protected by the low temperature Thomas so-lution (4°C)around it.Reperfusion of Thomas solution (4°C,10 ml/kg)was performed for 30 min and the heart was resuscitated by the perfusion of K-H fluid for 60 min.In the 0.5 MAC sevoflurane group (group Sev0.5 ),K-H fluid contained 0.5 MAC sevoflurane and other procedures were the same as in group IR.1.0 MAC sevoflurane group (group Sev1.0 ),K-H fluid contained 1.0 MAC sevoflurane and other procedures were the same as in group IR.2.0 MAC sevoflurane group (group Sev2.0),K-H fluid contained 2.0 MAC sevoflurane and other procedures were same as in group IR. HR,MAPs including time course (MAPD50,MAPD90)and MAP amplitude of endocardium,mid-layer myodardium and epicardium was recorded at the time of continuous balance perfusion for 1 5 min (T0),continuous perfusion for 15 min (T1),reperfusion for 15 min (T2)and 30 min (T3). Results Compared with T0and T1,HR was slower at T2and T3(P<0.05);Compared with group IR at T2and T3,HR in group Sev0.5 and group Sev1.0 was higher,that in group Sev2.0 was slower P<0.05);At T2,arrhythmia was observed in 6 rats in group IR,while arrhythmia was observed in 1 rats in group Sev0.5 ,and arrhythmia was observed in 2 rats in group Sev1.0 and arrhythmia was observed in 1 rats in group Sev2.0;Compared with group IR at T3,MAPD50in group Sev0.5 was shorter in three sites(P<0.05);Compared with group IR at T3,MAPD90in other three groups was shorter.Conclusion Different concentrations of sevoflurane can shorten MAPD90of MAPs,and the effects don＇t depend on the concertrations of sevoflurane when it changes from 0.5 MAC to 2.0 MAC;which may be the mechanism of decreased arrhythmias risk caused by sevoflurane.
