终末温血灌注对低温缺血再灌注心肌细胞微管蛋白的影响

目的：研究体外循环低温心肌保护中，采用终末温血灌注(TWBC)对心肌细胞微管蛋白(TB)组分的影响，探讨TWBC心肌保护作用的机制。方法：建立猫体外循环(CPB)模型，随机分为两组：组Ⅰ，间断冷血心停搏液灌注(ICBC)；组Ⅱ,先ICBC，主动脉开放前给予TWBC。动态观察不同时间点左心室收缩压峰值(LVSP)、左心室舒张末压(LVEDP)、左心室内压正负相最大变化速率［(±dp/dt)max］及达到最大收缩速率的时间［(t-dp/dt)max］。采用Western杂交技术，检测主动脉阻断(ACC)115、120 min、再灌注5、15、60、120 min时心肌TB含量，进行半定量分析。结果：(1)心脏再灌注120 min内，两组心功能差异显著(P<0.05)。(2)心肌细胞TB含量变化：ACC 120 min、再灌注5min时，两组游离、聚合TB含量差异均非常显著(P<0.01)。结论：TWBC能加速低温心肌保护中细胞TB聚合，有利于再灌注早期心功能恢复。

Effect of terminal warm blood cardioplegia on the changes of tubulin in myocardial cells after hypothermic ischemia and reperfusion

Objective: To elucidate the possible mechanism responsible for the improved protection of terminal warm blood cardioplegia (TWBC) after hypothermic cardiopulmonary bypass (CPB) through analysis of tubulin (TB) components changes in myocardial cells exposed to TWBC. Methods: Stable animal models of CPB were established in cats, which were then randomly divided into 2 groups. Group Ⅰ was subjected to intermittent cold blood cardioplegia (ICBC) whereas group Ⅱ to ICBC followed by TWBC before uncross-clamping. Left ventricular performance was then monitored and evaluated by LVSP, LVEDP, ±dp/dtmax and t-dp/dtmax in both groups and semi-quantitive analysis was conducted with Western blot method as to the content and constitution of TB in myocardial cells at 15 min, 120 min after aortic crossclamping (ACC) and 5 min,15 min, 60 min,120 min after reperfusion. Results: Within 120 min after reperfusion, systolic and diastolic functions decreased significantly in group Ⅰ as compared with group Ⅱ(P<0.05). At 115 min after ACC and 15 min after reperfusion, the content of free and polymerized TB in both groups had no difference (P>0.05). At 120 min after ACC and 5 minutes after reperfusion, there was a significant difference between groupⅠ andⅡ (P<0.01). Conclusion: TWBC accelerates the repolymerization of myocardial TB during hypothermic CPB, which may mediate the improved cardiac performance in the early stage of myocardial reperfusion.