钙敏感受体在缺氧/复氧诱导乳鼠心肌细胞凋亡中的作用

目的 探讨钙敏感受体(CaSR)对缺氧/复氧(A/R)所诱导乳鼠心肌细胞凋亡的影响及其机制.方法 原代培养乳鼠心室肌细胞缺氧2 h/复氧24 h,建立A/R心肌细胞损伤模型.心肌细胞随机分为三组:对照组、A/R组和CaSR激动剂氯化钆(GdCl3)组.四氮唑嗅盐法(MTT)检测细胞的存活率,原位缺口末端标记法(TUNEL)分析细胞凋亡率,蛋白印迹法检测CaSR、半胱氨酸天冬酶(caspase)-3、9和细胞色素c(Cytc)蛋白的表达.结果 TUNEL染色显示A/R后心肌细胞凋亡为(17±3)%,与对照相比,心肌细胞凋亡明显增加,CaSR表达也增加.CaSR激动剂GdCl3使心肌细胞凋亡进一步增加至(28±4)%,MTT检测表明心肌细胞存活率仅为(51.2±6.8)%;CaSR、caspase-3、caspase-9和Cytc表达进一步上调,明显高于A/R组.结论 CaSR通过线粒体Cytc-caspase-3途径参与了A/R所诱导的心肌细胞凋亡.

Effect of calcium-sensing receptor on anoxia/reoxygenation-induced apoptosis in cultured cardiomyocyte of neonatal rats

Objective Calcium-sensing receptor(CaSR)belongs to the family C of G-protein coupled receptors.This study was carried out to observe the influence and mechanism of CaSR on anoxia/reoxygenation(A/R)-induced cardiomyocytes apoptosis.Methods The model of A/R injury was established through anoxia for 2 hours and reoxygenation for 24 hours in cultured cardiomyocytes of neonatal rats.Cardiomyocytes were randomly divided into three groups:control group,A/R group and GdCl3 group(300μmol/L GdCl3 was added to the culture medium at the beginning of reoxygenation).Apoptosis of cardiomyocytes was assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL).The expression of CaSR,cysteine-requiring aspartate protease(caspase)-3,9 and cytochrom c (Cytc)were analyzed by Western blot.Results The TUNEL showed that cardiomyocytes apoptosis was 17%±3% in A/R group,and was higher than that in the control group.At the same time,expression of CaSR in A/R group was markedly increased in response to control group.Compared with A/R group,GdCl3,a specific activator of CaSR,further enhanced cardiomyocytes apoptosis to (28±4)% and decreased the ability of cardiomyocytes to (51.2±6.8)%,along with an increment in CaSR,caspase-3,caspase-9 and Cytc expressions.Conclusion CaSR is involved in anoxia/reoxygenation-induced apoptosis of neonatal rat cardiomyocytes through Cytc-caspase-3 pathway.