中文摘要：

目的：观察外源性硫化氢（H2S）对糖尿病大鼠心肌肌球蛋白轻链激酶（myosin light chain kinase,MLCK）表达的影响。方法：32只雄性SD大鼠随机分为正常对照组（NC组）、糖尿病对照组（DM组）、Na HS治疗组（DM＋Na HS组）和Na HS对照组（Na HS组）,每组8只。采用链脲佐菌素55 mg/kg腹腔注射诱导1型糖尿病大鼠模型。造模成功后,DM＋Na HS组和Na HS组大鼠腹腔注射Na HS溶液28μmol/kg干预治疗。8周后,测定大鼠左心室功能指标;计算心体比;测定血清乳酸脱氢酶（lactate dehydrogenase,LDH）和肌酸激酶同工酶（creatine kinase MB isozyme,CK-MB）水平;透射电镜观察心肌细胞超微结构变化;RT-PCR和Western印迹分别检测心肌组织MLCK m RNA和蛋白表达。结果：与NC组比较,Na HS组各项指标差异无统计学意义（均P〉0.05）,而DM组左心室收缩和舒张功能下降,心体比明显增大（均P〈0.01）,血清中LDH和CK-MB水平明显增高（均P〈0.01）,心肌超微结构损伤明显,心肌组织MLCK m RNA和蛋白表达明显降低（均P〈0.01）。与DM组比较,DM＋Na HS组左心室功能和心肌超微结构损伤明显改善,心体比明显降低（均P〈0.05）,血清中LDH和CK-MB水平明显下降（均P〈0.01）,MLCK m RNA和蛋白表达明显升高（均P〈0.01）。结论：外源性H2S对糖尿病大鼠心肌损伤具有保护作用,机制可能与增强心肌MLCK表达有关。

英文摘要：

Objective：To investigate the effect of hydrogen sulfide（H_2S） on cardiac myosin light chain kinase（MLCK） expression in diabetic rats.Methods：A total of 32 male SD rats were randomly divided into a normal control group（NC group）,a diabetic control group（DM）,a NaHS treatment group（DM＋NaHS） and a NaHS group（NaHS）（n=8 in each group）.Intraperitoneal injection of streptozotocin was utilized to establish Type 1 diabetic rat model.The diabetic rats in the DM＋NaHS and NaHS groups were intraperitoneally injected with 28 μmol/kg NaHS solution.Eight weeks later,the ventricular hemodynamic parameters,the ratio of heart weight/body weight（HW/BW ratio）,the levels of lactate dehydrogenase（LDH） and creatine kinase MB isozyme（CK-MB） in serum were determined.The ultrastructures of myocardium were observed under electron microscopy.The expressions of MLCK mRNA and protein level in myocardium were detected by RT-PCR and Western blot,respectively.Results：Compared with the NC group,there was no significant difference in the various indexes in the NaHS group（all P〉0.05）.The function of left ventricular contract and relaxation were decreased obviously in diabetic rats,while the HW/BW ratio was increased（all P〈0.01）.The levels of LDH and CK-MB were increased（both P〈0.01）in serum,while the levels of MLCK mRNA and protein were decreased significantly（both P〈0.01） in myocardial tissues.Compared with the DM group,the left ventricular hemodynamic parameters and myocardial ultrastructure damage were improved in the DM＋NaHS group,while the HW/BW ratio was decreased（all P〈0.05）.The levels of LDH and CK-MB were decreased（both P〈0.01）,while the levels of MLCK mRNA and protein were increased significantly（both P〈0.01）.Conclusion：H_2S can protect myocardium in diabetic rats,which may be associated with upregulation of cardiac MLCK.