背景：近几年来研究发现内质网应激导致细胞凋亡在细胞缺血性损害中起重要作用，成为缺血心肌的研究热点。下肢缺血预处理对未成熟心肌具有明显保护作用，但下肢缺血预处理对未成熟心肌内质网应激细胞凋亡是否存在影响至今未知。 目的：探讨下肢缺血预处理对未成熟心肌内质网应激和细胞凋亡的影响。 方法：采用兔离体心脏Langendorff灌注模型，24只幼兔随机分为3组：对照组仅灌注KH液180 min；缺血再灌注组心脏灌注20 min后，停灌60 min，复灌100 min；下肢缺血预处理组，反复3次阻断双下肢血流5 min/放5 min，建立Langendorff模型，然后重复缺血再灌注组方法。TUNEL法检测心肌细胞凋亡率、Western blot检测GRP78、Bcl-2、Bax和Fas蛋白表达。 结果与结论：下肢缺血预处理组与缺血再灌注组比较，心肌细胞凋亡率明显减少；Bcl-2表达明显增多，GRP78、Bax、Fas表达明显减少。结果表明下肢缺血预处理可能通过调控内质网过度应激GRP78表达以及Bcl-2、Bax、Fas蛋白的表达调控心肌细胞凋亡。%BACKGROUND:In recent years, endoplasmic reticulum stress-caused apoptosis plays a crucial role in ischemia impairment and has become the hotspot of studies addressing myocardial ischemia/reperfusion (I/R) injury. The lower limb ischemic preconditioning (LIP) has the obvious protective effect on the immature myocardium, but until now, no study reports whether LIP effects on endoplasmic reticulum stress apoptosis in immature myocardial cells. OBJECTIVE:To investigate the effect of LIP on endoplasmic reticulum stress and apoptosis. METHODS:Langendorff-perfused isolated rabbit hearts were used in this study. Twenty-four immature rabbits were randomized into three groups. Control group:Isolated rabbit heart was only perfused with Krebs-Henseleit for 180 minutes. I/R group:Isolated rabbit heart was perfused 20 minutes, and then ischemia for 60 minutes fol owed by reperfusion 100 minutes. LIP group:Limbs were repeatedly obstructed 5 minutes and relaxed 5 minutes for three times, to establish Langendorff models, and then repeated the method of ischemia/reperfusion in I/R group. The myocardial apoptosis was assayed with TUNEL method. The expression of glucose-regulated protein 78, Bcl-2, Bax and Fas was detected with western blot analysis. RESULTS AND CONCLUSION:Compared with I/R group, apoptosis rate was significantly lower, the expression of Bcl-2 was significantly higher, and the expression of glucose-regulated protein 78, Bax and Fas was significantly lower in LIP group. This study demonstrated that LIP regulates myocardial cellapoptosis through reducing the expression of endopasmic reticulum stress GRP78, Bax and Fas and increasing the expression of Bcl-2.
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