高温预处理对过氧化氢诱导大鼠心肌细胞线粒体金属硫蛋白表达的影响

Effect of high temperature preconditioning on hydrogen peroxide-induced expression of mitochondrial metallothionein in rat cardiomyocytes

目的探讨高温预处理对过氧化氢（H2O2）诱导大鼠心肌细胞线粒体金属硫蛋白（MT）表达的影响。方法采用随机数字表法，将体外培养的H9C2大鼠心肌细胞分为3组（n=6）：正常对照组（C组）心肌细胞加入含血清DMEM培养基，置于37℃5％c02培养箱中3h；H202组加入含0．5mmol／LH，02的无血清DMEM培养基，置于37℃5％c0：培养箱中孵育3h；高温预处理组（HTTP组）加入含血清DMEM培养基，置于42℃恒温水浴1h，行高温预处理，然后在37℃5％CO2细胞培养箱中孵育12h，去除DMEM培养基，随后处理同H2O2组。采用流式细胞术测定心肌细胞凋亡率；观察心肌细胞线粒体超微结构；采用Westernblot法测定线粒体MT的表达。结果与c组比较，H202组和HTP组细胞凋率升高，线粒体MT表达上调（P〈0．01）；与H2O2组比较，HTP组细胞凋率降低，线粒体MT表达上调（P〈0．01）。HTP组心肌细胞线粒体损伤较H2O2组减轻。结论高温预处理减轻H2O2诱导大鼠心肌细胞损伤的机制可能与上调线粒体MT表达，增强心肌内源性保护机制有关。

Objective To investigate the effects of high temperature preconditioning on hydrogen peroxide （ H2 O2 ）-induced expression of mitochondrial metallothionein （MT） in rat cardiomyocytes. Methods The rat car- diomyocytes H9C2 cultured in vitro were randomly divided into 3 groups （ n = 6 each） ： control group （group C） ; H2O2 group （group H5 02 ）; high temperature preconditioning group （group HTP）. The cells were continuously cultured for 3 h in group C. The cells were cultured for 3 h in serum-free DMEM liquid culture medium containing H2O2 0.5 mmol/L in an incubator filled with 5% CO5 at 37 ℃ in group H202 In group HTP, the cells were cultured in serum-containing DMEM liquid culture medium, then placed in a warm bath of 42 ℃ for 1 h, cultured for 12 h in an incubator filled with 5% CO5 at 37 ℃, DMEM liquid culture medium was then removed, and the other procedures were similar to those previously described in group H2O2. Myocardial cell apoptosis was observed by flow cytometry. The apoptotic rate was calculated. The ultrastructure of myocardial mitochondria was examined with electron microscope. The expression of mitochondrial MT in cardiomyocytes was determined using Western blot. Results Compared with group C, the apoptotic rate was significantly increased, and the expression of mitochon- drial MT was up-regulated in groups H2O2 and HTP （P 〈 0.01）. The apoptotic rate was significantly lower, and the expression of mitochondrial MT was higher in group HTP than in group H2O2 （ P 〈 0.01 ）. The mitochondrial injury was attenuated in group HTP as compared with group H2O2. Conclusion The mechanism by which high temperature preconditioning reduces H2O2-induced myocardial damage may be related to up-regulation of expression of mitochondrial MT in cardiomyocytes and endogenous myocardium-protective mechanism in rats.