不同预处理方法对成年大鼠心肌保护效果的对比研究

Comparison of cardioprotection effects between varied preconditioning methods on myocardial ischemia / reperfusion injury

目的探讨不同预处理方法对缺血再灌注损伤大鼠心肌保护的效果及其可能机制。方法建立Langendorff离体心脏灌注模型,20只SD成年大鼠根据预处理方式分为对照组、缺血预处理组、AG490预处理组和Rapamycin预处理组,每组5只。比较各预处理组左心室发展压(LVDP)、等容收缩期左心室内压上升最大变化速率(Max Dp/dt)、等容舒张期左心室内压下降最大变化速率(Min Dp/dt)等心脏功能参数和心肌组织损伤情况,检测STAT3及其磷酸化水平、自噬相关蛋白LC3和LAMP2蛋白表达水平。结果缺血预处理组、AG490预处理组、Rapamycin预处理组的LVDP、Max Dp/dt、Min Dp/dt均显著优于对照组。AG490预处理组与Rapamycin预处理组之间在Max Dp/dt和Min Dp/dt上有差异,但AG490预处理组与缺血预处理、Rapamycin预处理与缺血预处理之间无显著差异。缺血预处理组、AG490预处理组和Rapamycin预处理组心肌组织凋亡水平均低于对照组,但3组间差异无统计学意义。缺血预处理组STAT3水平最高,AG490组和Rapamycin组其次,但均高于对照组水平;AG490组P-STAT3水平明显低于缺血预处理组和Rapamycin预处理组,接近对照组。Rapamycin组LC3水平最高,缺血预处理组和AG490组接近,但均显著高于对照组。而代表心肌自噬溶酶体功能的LAMP2水平,在缺血预处理组最强,Rapamycin预处理和AG490预处理组其次,但均显著高于对照组。结论 AG490预处理对成年大鼠心肌保护效果与缺血预处理、Rapamycin预处理相当,其机制可能并非通过经典的JAK/STAT信号作用途径实现,而可能与其诱导的保护性自噬相关。

Objective To compare cardioprotection effects between varied preconditioning methods on myocardial ischemia/reperfusion injury. Methods Twenty adult SD rats were divided into 4 groups：ischemia preconditioning group, AG490 preconditioning group, Rapamycinpreconditioning group and control group. Parameters of cardiac function, including left ventricle developing pressure, Max Dp/dt and Min Dp/ dt,were recorded with Powerlab system in a Langendorff isolated perfused heart model. Myocardial apoptosis was evaluated with TUNEL. STAT3 ,p-STAT3 ,LC3 and LAMP2 level was detected with Western Blot. Results Cardiac function of all preconditioning groups was better than that of control group. Both Max Dp/dt and Min Dp/dt of AG490 preconditioning group were higher than those of Rapamyein precondi- tioning group. There was no difference between any drug preconditioning group （AG490 or Rapamycin） and ischemia preconditioning group. The myocardial apoptosis rate in AG490 preconditioning group was similar with other two preconditioning groups, lower than that in control group. P-STAT3 level in AG490-preconditioning group was obviously lower than that in the other two preconditioning group. LC3 level in AG490-preconditioning group was similar with that in ischemia-preconditioning group, and LAMP2 level was higher than that in control group although lower than that in ischemia- or Rapamycin-preconditioning group. Conclusion AG490 preconditioning protected against myocardial ischemia/reperfusion injury, similar with isehemia- and Rapamyein-preconditioning methods, which may possibly resulted from autophagy, in- stead of the classic JAK/STAT pathway.