慢性心衰大鼠心肌细胞内雷尼丁受体及集钙蛋白的表达

Expression of ryanodine receptor and calsequestrin in myocardial cells of chronic heart failure rat

目的： 研究慢性心衰大鼠心肌细胞内雷尼丁受体（RyR2）及其调节蛋白集钙蛋白的表达,探讨心衰心肌细胞内钙容量降低的机制.方法： 雄性SD大鼠被随机分为心衰组和假手术组,运用激光扫描共聚焦显微镜、透射电子显微镜、免疫印迹等方法研究2组大鼠心肌细胞肌浆网内钙容量、心肌细胞超微结构及心肌细胞内肌浆网钙释放通道RyR2和其调节蛋白集钙蛋白表达的变化.结果： 慢性心衰大鼠心功能左心室舒张末期压力、左室压力最大上升速率均显著低于假手术组.假手术组大鼠心肌细胞的肌小节完整,肌丝排列整齐,线粒体结构正常;心衰组大鼠部分心肌细胞肌丝溶解,线粒体肿胀,嵴断裂.慢性心衰大鼠心肌细胞肌浆网内钙容量显著低于假手术组.慢性心衰大鼠心肌细胞内RyR2的表达量无明显变化,集钙蛋白表达明显下降.结论： 慢性心衰大鼠心肌细胞内集钙蛋白表达下调,可能是导致心肌细胞肌浆网钙容量减少的原因之一.

Objective： To study the expression of ryanodine receptor（RyR2） and calsequestrin in myocardial ceils of chronic heart failure rat and its role in regulating calcium content. Methods： Adult male SD rats were randomized to receive either heart failure（HF） or a sham procedure. The sarcoplasmic reticulum（SR） Ca^2＋ content, the ultrastructure of myocardial cells in left ventricle of rats were investigated and the expression of RyR2 and calsequestrin was assessed by using laser scanning confocal microscope, transmission electron microscopy and Western blotting. Results： The left ventricular end-diastolic pressure and the maximal change of systolic pressure over time（dp/dtmax ） in HF rats statistically differed from sham rats. Histologically, dissolution of myofilaments, swelling of mitochondria and breakage of mitochondrial crista were detectable in myocardial cells of HF rats, while complete sarcomere, regularly arranged myofilaments and normal mitochondria were clearly visualized in sham animals. Besides, SR Ca^2＋ coment（△F/F0 ）was dramatically reduced in sham myocardial cells and HF myocytes. Calsequstrin was statistically down-regulated its protein level in HF myocytes compared to those from sham. But, statistical difference was undetectable in expression of RyR2 in different treated myocardial cells. Conclusion： Down-regulation of calsequestrin in chronic heart failure rat could contribute to reduced SR Ca^2＋ content.