缺血预适应对体外循环中心肌细胞膜通透性变化的影响

Effect of ischemic preconditioning on alteration of myocardial cell membrane permeability of felines during cardiopulmonary bypass

目的 :观察缺血预适应 (IPC)对体外循环 (CPB)中缺血再灌注损伤所致心肌细胞膜通透性变化的影响。 方法 :建立猫体外循环模型并随机分为 4组 :对照组 (n=30 )仅做单纯并行 CPB转流 ,不阻断升主动脉 (ACC) ;缺血再灌注组 (IR组 ,n=30 )于 CPB开始 4 5 min后 ACC6 0 m in,开放主动脉使心脏恢复再灌注 ;单次 IPC组 (IPC组 ,n=30 )于 ACC前进行 1次 IPC(ACC5 min后开放 1 0 m in) ,余同 IR组 ;多次 IPC组 (IPCs组 ,n=30 )于 ACC前进行 3次 IPC,余同 IR组。应用细胞化学 -镧示踪法观察心肌细胞膜通透性的变化情况 ,同时测定心肌组织中 Ca2 +含量。 结果 :IR组在 ACC早期镧颗粒即出现于心肌细胞内 ,且随主动脉阻断时间的延长而逐渐增多并进入心肌细胞线粒体中 ;再灌注早期 ,胞质和线粒体内镧颗粒流入加快 ;同时心肌 Ca2 +含量在 ACC30 min开始逐渐升高 ,心脏再灌注期间 ,Ca2 +含量进一步增加 (P<0 .0 1 )。而 IPC组与 IR组相比无明显差别。IPCs组各时间点细胞内镧颗粒沉积明显少于 IR组 ,且线粒体中较晚出现镧颗粒 ;IPCs组心肌组织 Ca2 +含量在 ACC6 0 m in以及再灌注期间虽较对照组有所升高 (P<0 .0 5 ) ,但升高幅度明显低于 IR组。结论 :多次 IPC有助于减轻或延迟 CPB期间缺血再灌注所导致的心肌细胞膜通透?

Objective:To observe the influences of ischemic preconditioning(IPC) on the changes of ischemia and reperfusion(IR) myocardial cell permeability during cardiopulmonary bypass (CPB). Methods: Totally 120 felines were randomized into 4 groups: control group( n =30), in which CPB was conducted without aortic cross clamping (ACC); IR group( n =30), with 60 min ACC followed by 90 min reperfusion, and cardioplegia was used during ACC; IPC group( n =30), with protocol similar to that of IR group except for “1×5” IPC applied before ACC; IPCs group ( n =30), with protocol similar to that of IR group except for “3×5” IPC applied before ACC. The permeability of myocardial cells was monitored under the electron microscopy with lanthanum (La 3+ ) tracing technique. Myocardial Ca 2+ content was also determined simultaneously. Results: Compared with IR group, less intracellular La 3+ granules were detected in myocardial cells in IPCs group, and mitochondrial lanthanum deposits appeared later during the periods of ACC and reperfusion.Although myocardial Ca 2+ content in IR group was significantly increased after 30 min cardiac arrest with ACC and during myocardial reperfusion, three cycle IPC significantly reduced the rise in myocardial Ca 2+ content. There were no significant differences in intracellular La 3+ deposits density and in myocardial Ca 2+ content between IPC group and IR group. Conclusion: Multiple IPC may be effective in alleviating the increase of membrane permeability and attenuate the accumulation of calcium in myocardium caused by IR injury during CPB.