缺血预处理对体外循环中左心功能的恢复及心肌细胞膜流动性变化的影响

目的:观察缺血预处理(IPC)对体外循环(CPB)中心肌细胞膜流动性变化及心功能恢复的影响,评价IPC的心肌保护作用。方法:将72只健康家猫随机分为3组:单纯并行循环(CPB)组、缺血再灌注(IR)组和IPC组。监测CPB中猫左心室内压峰值(LVSP)、左心室等容收缩期压力升高最大速率(dp/dtmax)、左心室舒张期压力下降最大速率(dp/dtmin)等左心功能指标,并应用荧光偏振法测定心肌细胞膜的微黏度(η),以η的倒数表示心肌细胞膜脂流动性。结果:CPB组体外循环过程中左心功能各指标和心肌细胞膜微黏度均无明显变化;IR组主动脉阻断(ACC)期间η明显上升且于再灌注期间进一步升高,IPC组ACC期间η无明显变化,再灌注期间虽有所升高但明显低于IR组;心功能恢复阶段IPC组猫心LVSP、dp/dtmax和dp/dtmin均明显高于IR组。结论:IPC能够有效维持CPB中缺血再灌注心肌细胞膜脂的流动性,同时可改善左心功能的恢复。

Effect of ischemic preconditioning on left cardiac function and fluidity of myocardial cell membrane during cardiopulmonary bypass

Objective：To elucidate the effect of ischemic preconditioning（IPC）on left cardiac function and fluidity of myocardial cell membrane during cardiopulmonary bypass （CPB）. Method：Seventy-two felines were randomized into three groups： Group 1 （CPB group, n=24）, in which CPB was conducted without aortic cro-ssclamping （ACC）; Group 2 （IR group, n=24）, with 60 min ACC followed by 90 min reperfusion; Group 3 （IPC group, n=24）, with protocol similar to that of group 2 except for three-cycle application of 15 min IPC before ACC. Left cardiac function was evaluated by monitoring LVSP, dp/dtmax and dp/dtmin, and microviscosity of myocardial membrane, was evaluated during CPB in all groups by using fluorescence polarization technique. Result：Decreased LVSP, dp/dtmax and dp/dtmin were found during reperfusion period in IR group. In IPC group, LVSP, dp/dtmax and dp/dtmin were significantly higher than that in IR group. Microviscosity of myocardial cell membrane which markedly increased in IR group kept unchanged in IPC group during ACC period,but was higher compared to CPB group and significantly lower than that in IR group.Conclusion：IPC can protect myocardial cells from ischemia and reperfusion injury by maintaining the fluidity of myocardial membrane during CPB, which may be helpful for the recovery of cardiac funtion during reperfusion period.