心肌缺血和低氧模型大鼠心肌组织琥珀酸受体表达的变化

Changes in succinate receptor expression in myocardial tissue of rats with myocardial ischemia and hypoxia

目的利用心肌缺血、低氧模型大鼠,检测大鼠心肌组织琥珀酸(盐)受体(GPR91)表达的变化,以分析心肌缺血、低氧与GPR91表达的关系。方法分别制备大鼠冠状动脉结扎所致心肌缺血模型、模拟高原环境所致心肌低氧模型。前者由结扎大鼠心脏左冠脉前降支诱发,包括假手术组、左冠脉结扎12 h组和24 h组,每组6只,记录各组大鼠心电图,以氯化三苯基四氮唑染色法显示心肌组织梗死程度并计算梗死比例,自动生化分析仪检测血清中乳酸脱氢酶(LDH)、肌酸激酶(CK)以及心肌肌钙蛋白T(c Tn-T)的含量变化,对制备模型加以鉴定;后者利用专用低压舱模拟高原低氧环境诱发,设正常气压组、低气压环境生存1、3、5和7 d组,每组6只,检测大鼠血清中LDH、CK及c Tn-T含量的变化。分别以实时荧光定量PCR法和Western印迹法,检测上述各组大鼠心肌组织GPR91 mRNA和蛋白的表达水平,每组动物检测3只。结果与假手术组大鼠比较,冠脉结扎12和24 h组大鼠的心电图均表现为ST段弓背型抬高,心肌梗死面积比例分别为(23. 18±3. 46)%及(34. 85±2. 22)%(P <0. 05),血清中LDH、CK及c Tn-T的含量均明显增加(P <0. 01);与正常气压组比较,低压环境生存1、3、5和7 d组大鼠血清LDH、CK及c Tn-T的含量升高明显(P <0. 01)。GPR91表达检测结果显示,冠脉结扎12、24 h组大鼠心肌组织mRNA和蛋白水平均出现上调(vs假手术组,P <0. 01、P <0. 05);低压1、3、5和7 d组大鼠心肌GPR91的mRNA表达明显增加(vs正常气压组,P <0. 05),其蛋白表达增加以7 d组最为明显(vs正常气压组,P <0. 05)。结论大鼠心肌在缺血、低氧过程中,反映心肌组织受损的血清学指标LDH、CK及c Tn-T含量明显增加,与此同时,心肌组织GPR91的mRNA及蛋白表达显著上调。提示GPR91具有心肌缺血、低氧防治的潜在靶点意义。

Objective To detect the succinate receptor( GPR91) expression in myocardial tissue of rats with myocardial ischemia and hypoxia. Methods A total of 48 Sprague-Dawley( SD) rats were used in the experiment. For the induction of myocardial ischemia,eighteen rats were randomly divided into three groups: sham operation,coronary artery ligation 12 and 24 h,respectively. The rats were anaesthetized with sodium pentobarbital and ligated by the left anterior descending artery for 12 and 24 h. The control rats received the same operation except for ligation. The electrocardiogram( ECG),area of myocardial infarction and serum contents of lactate dehydrogenase( LDH),creatine kinase( CK) and cardiac troponin T( c Tn-T) in rats were recorded and detected at the designated time. For the induction of myocardial hypoxia,thirty rats were divided into five groups: those living under a normal atmosphere,and those living in a low atmosphere for 1,3,5 and 7 d. On the designated days,the serum contents of LDH,CK and c Tn-T in rats were detected.Real-time fluorescent quantitative PCR and Western bloting were used for determination of GPR91 mRNA and protein expressions in rat myocardium. Results In rats ligated by the left anterior descending artery for 12 and 24 h,continuous ST segment elevations were recorded in ECG,the percentage of infarct size was( 23. 18 ± 3. 46) % and( 34. 85 ± 2. 22) %( P < 0. 05,compared with the control),and the serum levels of LDH,CK and c Tn-T were increased to some extent. In rats with myocardial hypoxia for 1,3,5 and 7 d,elevation of LDH,CK and c Tn-T contents in serum was also detected.Compared with the control,the expressions of GPR91 mRNA and protein in the myocardium of myocardial ischemia or hypoxia rats were both up-regulated. Conclusion The left anterior descending artery ligation or living under a low atmosphere can induce myocardial ischemia or hypoxia in rats. The expression of GPR91 mRNA and protein in the myocardium of rats with myocardial ischemia or hypoxia is increased. GPR91 could serve as a target for prevention and treatment of ischemica or hypoxia.