缺血预适应对猫体外循环前后心肌细胞膜脂流动性的影响

Effect of ischemic preconditioning on myocardial cell membrane fluidity before and after feline cardiopulmonary bypass

目的 :观察缺血预适应 (IPC)对猫体外循环 (CPB)前后心肌细胞膜脂流动性的影响。方法 :建立猫 CPB模型并随机分成 3组 :对照组 (n=30 )仅作单纯并行 CPB转流 ;缺血再灌注组 (IR组 ,n=30 )于 CPB开始 4 5 min后阻断升主动脉 (ACC)6 0 min,开放主动脉恢复再灌注 90 min;IPC组 (n=30 )于 ACC前进行 3轮 IPC(ACC5 min后开放 1 0 min) ,余同 IR组。应用化学滴定法测定心肌组织磷脂酶 A2 (PL A2 )活性 ,气相色谱测定膜脂多不饱和脂肪酸 (PU FA)及饱和脂肪酸 (SFA)含量并计算 PU FA/ SFA比率 ,荧光偏振法测定心肌细胞膜微黏度 (η) ,以 η的倒数表示心肌细胞膜脂流动性。结果 :IR组在 ACC期间心肌细胞膜微黏度和 PL A2 活性明显升高且于再灌注期间进一步升高 (P<0 .0 5 ,P<0 .0 1 ) ,而 PU FA、SFA含量在 ACC期间显著降低并于再灌注期间进一步减少 (P<0 .0 5 ,P<0 .0 1 ) ,再灌注期间 PU FA/ SFA比率亦迅速下降 (P<0 .0 1 ) ;IPC组在ACC期间心肌细胞膜微黏度无明显变化 ,再灌注期间虽有所升高但明显低于 IR组 (P<0 .0 5 ) ,心肌组织 PL A2 活性在 ACC及再灌注期间均明显低于 IR组 (P<0 .0 1 ) ,同时膜脂中 PU FA、SFA含量以及 PUFA/ SFA比率均明显高于 IR组 (P<0 .0 5 ,P<0 .0 1 )。结论 :IPC能够较有效维持

Objective:To evaluate the effect of ischemic preconditioning(IPC) on myocardial cell membrane fluidity in feline heart with cardiopulmonary bypass(CPB).Methods: Ninety felines were randomized into 3 groups: control group( n =30),in which CPB was conducted without aortic cross clamping(ACC);IR group( n =30),with 60 min cardiac arrest under ACC followed by 90 min reperfusion,and cardioplegia was used during period of AAC;IPC group( n =30),with protocol similar to that of IR group except for three cycle 15 min IPC applied before ACC.The contents of the major long chain fatty acid including polyunsaturated fatty acids(PUFA) and saturated fatty acids(SFA) were determined by gas liquid chromatography,and myocardial PLA 2 activity was simultaneously measured.The microviscosity,in terms of reciprocal of myocardial membrane fluidity,was monitored by fluorescence polarization.Results: Microviscosity of myocardial cell membrane,which was markedly increased in IR group( P <0.05, P <0.01),kept unchanged in IPC group during ACC period.During reperfusion period,the microviscosity in IPC group was higher compared to that of control group( P <0.05) and significantly lower than that in IR group( P <0.05).Elevated myocardial PLA 2 activity was found in IR group with correspondingly decreased PUFA and SFA contents during ACC and reperfusion period( P <0.05, P <0.01).However,IPC significantly attenuated the activation of PLA 2 and PUFA and SFA contents( P <0.05).Conclusion: IPC can suppress the activation of myocardial PLA 2,leading to incorporation of more PUFA in membrane phospholipids,which may be, at least partially, responsible for maintaining the membrane fluidity of feline heart subjected to reperfusion injury under CPB.