Objective To investigate the effects of sevoflurane preconditioning(SevoPC) and postconditioning(SevoPoC) on reperfusion arrhythmia of isolated rat heart.Methods Fifty SD rats were set up as isolated heart perfusion models and randomly divided into 5 groups,with 10 rats in each group.In control group,isolated hearts were treated with preoxygenated KH constant perfusion for 110 min.In ischemia-reperfusion injury(I/RI) group,KH was withdrawn for 20 min after 30 min perfusion and reperfused for 60 min to establish I/RI models.In SevoPC group,isolated hearts were treated with KH with 3％ sevoflurane constant perfusion for 15 min after 15 min KH perfusion to establish I/RI models.In SevoPoC group,KH was withdrawn for 20 min after 30 min perfusion,KH with 3％ sevoflurane was perfused for 15 min and preoxygenated KH was perfused for 45 min.In sevoflurane preconditioning with postconditioning(PCPo) group,KH with 3％ sevoflurane was perfused for 15 min after 15 min KH perfusion,then perfusion was suspended for 20 min,KH with 3％ sevoflurane was reperfused for 15 min and preoxygenated KH was perfused for 45 min.Heart rate (HR),left ventricular developed pressure (LVDP),maximum LVDP increase rate(± dp/dt),maximum LVDP decrease rate(-dp/dt) and left ventricular end-diastolic pressure(LVEDP) were measured.Myocardial infarct size and cardiac tropon I(cTnI) in coronary flow were tested.Reperfusion arrhythmia was recorded.Protein and gene expression levels of L-type calcium channel (LTCCs),ryanodine receptor 2 (RyR2) and sodium-calcium exchanger 1 (NCX1) were determined by western blotting and polymerase chain reaction.Results LVDP,± dp/dt,-dp/dt,HR in SevoPC group,SevoPoC group,PCPo group were significantly higher and LVEDP were significantly lower than those in I/RI group 30,60 min after reperfusion(P ＜ 0.05).Myocardial infarct size and cTnI level in SevoPC group and SevoPoC group were significantly lower than those in I/RI group [(17.9 ± 2.1) ％,(17.2 ± 2.3) ％ vs (23.8 ± 2.1) ％;(0.061 2 ± 0.002 0),(0.059 2 ± 0.003 1) mg/L vs (0.113 4 ± 0.004 3) mg/L] (P ＜ 0.05).Times of ventricular extrasystole,attack durations of ventricular tachycardia and ventricular fibrillation,incidences of ventricular fibrillation and reperfusion arrhythmia scores in SevoPC group and SevoPoC group were siginificantly lower than those in I/RI group (P ＜ 0.05).Protein expression levels of RyR2 in SevoPC group,protein expression levels of LTCCs,RyR2,NCX1 and gene expression levels of RyR2,NCX1 in SevoPoC group were siginificantly lower than those in I/RI group (P ＜ 0.05).Conclusion SevoPC and SevoPoC can improve heart function after I/RI and reduce the occurrence of reperfusion arrhythmia of isolated rat heart;the mechanism may be associated with the inhibition on LTCCs,RyR2 and NCX1.%目的 探讨七氟烷预处理(SevoPC)与七氟烷后处理(SevoPoC)对大鼠离体心脏再灌注心律失常的影响.方法 建立SD大鼠离体心脏灌注模型,将50只SD大鼠离体心脏完全随机分为5组,每组10只:①时间对照组:离体心脏恒流灌注充分预氧合的KH液110min;②I/RI组:离体心脏平衡30 min后,KH液停止灌注20 min,恢复恒流灌注预氧合的KH液60 min,建立缺血再灌注(I/RI)损伤模型;③SevoPC组:离体心脏平衡15 min后,使用含3％七氟烷饱和的KH液持续灌注15 min,建立I/RI损伤模型;④SevoPoC组:离体心脏平衡30 min后,停止灌注20min,在复灌即刻使用含3％七氟烷饱和的KH液持续灌注15 min,然后使用预氧合的KH液灌注45 min;⑤七氟烷联合处理组(PCPo组):离体心脏平衡15 min后,使用含3％七氟烷饱和的KH液持续灌注15 min,停止灌注20 min,在复灌即刻使用含3％七氟烷饱和的KH液持续灌注15 min,然后使用预氧合的KH液灌注45 min.各组均持续监测心率、左心室发展压(LVDP)、最大LVDP上升速率(± dp/dt)、最大LVDP下降速率(-dp/dt)及左心室舒张末期压力(LVEDP).检测心肌梗死面积和冠状动脉流出液中心肌肌钙蛋白I(cTnI)水平并监测记录再灌注心律失常.分别用蛋白质印迹法和实时荧光定量聚合酶链反应检测L型钙通道(LTCCs)、兰尼碱受体2(RyR2)以及钠钙交换体1(NCX1)的蛋白和基因转录水平.结果 与I/RI组比较,SevoPC组、SevoPoC组、PCPo组的离体心脏在再灌注30 min及60 min的LVDP、+dp/dt、-dp/dt以及心率均升高,LVEDP均降低(均P＜0.05).SevoPC和SevoPoC均能减少由I/RI造成的心肌梗死面积[(17.9±2.1)％、(17.2±2.3)％比(23.8±2.1)％,P＜0.05]并减少cTnI的释放[(0.061 2 ±0.002 0)、(0.059 2 ±0.003 1)mg/L比(0.113 4 ±0.004 3)mg/L,P＜0.05].与I/RI组相比,SevoPC和SevoPoC能够明显减少室性期前收缩的次数,缩短室性心动过速和心室颤动的发作时间,降低心室颤动的发生率,并且能够降低再灌注心律失常评分(均P ＜0.05).SevoPC组RyR2的蛋白相对表达量明显低于I/RI组,SevoPoC组LTCCs、RyR2及NCX1的蛋白相对表达量均明显低于I/RI组,RyR2及NCX1的基因相对表达水平明显低于I/RI组(均P＜0.05).结论 SevoPC及SevoPoC均能够改善I/RI损伤后的心功能并能改善离体大鼠心脏的再灌注心律失常发生情况,其作用可能与其对LTCCs、RyR2及NCX1的抑制有关.
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