中文摘要：

目的研究糖尿病大鼠膈肌功能及钙调控蛋白基因表达的变化，探讨糖尿病大鼠膈肌功能损伤的发生机制。方法使用链脲佐菌素建立糖尿病大鼠模型，SD大鼠随机分为糖尿病组（随机血糖≥16．7mmol／L）和正常对照组，造模后4周、8周测定大鼠体质量和膈肌／体质量比值，生化指标检测各组大鼠空腹血糖和膈肌组织线粒体琥珀酸脱氢酶（SDH）活性；应用体外灌流大鼠膈肌条的方法，测定单收缩张力、最大强直张力、峰值收缩时间、半舒张时间、张力．频率曲线，电镜观察大鼠膈肌超微结构，采用RT-PCR检测大鼬鬲肌肌质网钙泵（sERcA）和受磷蛋白（PLB）mRNA表达。结果（1）与正常对照组相比，糖尿病大鼠体质量和膈肌质量，体质量比值均明显降低（P〈0．01），膈肌组织SDH的活性显著降低（P〈0．01）；（2）在给予大鼠膈肌条10、20、40、60、100Hz刺激时，糖尿病大鼠月鬲肌在各频率下的收缩张力明显低于正常对照组（P〈0．01）；膈肌力学指标单收缩张力和最大强直张力明显降低，峰值收缩时间和半舒张时间明显延长（P〈0．01）；（3）超微结构显示糖尿病组大鼠膈肌组织损伤明显，肌纤维断裂，肌质网扩张，线粒体水肿，数目减少，脊断裂，空泡化或囊泡化，同时可见随病程延长膈肌损伤明显加重；（4）RT-PCR结果提示：与正常对照组相比，糖尿病组大刚鬲肌SERCAmRNA表达均明显降低（P〈0．01），糖尿病大鼠膈肌SERCAmRNA表达8周组比4周组明显降低（P〈0．01），糖尿病大鼠膈肌PLBmRNA表达显著增强（P〈0．01）。结论糖尿病大鼠膈肌超微结构受到破坏，线粒体损伤和数目减少，线粒体SDH活眭降低，ATP生成减少，膈肌组织SERCAmRNA表达减少和PLBmRNA表达增强，引起膈肌肌质网摄取Ca^2＋减少，促成膈肌收缩和舒张功能损伤。

英文摘要：

Objective To study the changes in diaphragmatic function and gene expressions of calcium regulatory proteins in diabetic rats and explore the mechanism of diaphragm dysfunction in diabetes mellitus. Methods SD rats were randomly divided into normal control group and diabetic （induced by intraperitoneal STZ injection） group. After 4 and 8 weeks, the body weight and diaphragm to body weight ratio were measured, and the activities of succinic dehydrogenase （SDH） in the diaphragm and blood glucose were assayed. The diaphragm contractility was assessed and the alterations of diaphragm ultrastructure were observed. RT-PCR was used to detect the changes in sarcoplasmic reticulum Ca^2＋-ATPase （SERCA） and phospholamban （PLB） mRNA expressions in the diaphragm. Results The diabetic rats showed a significant weight loss with a lowered diaphragm to body weight ratio （P〈0.01） and SDH activity （P〈0.01）. The peak twitch tension and maximum tetanic tension of the diaphragm were significantly lowered and the time to peak contraction and half relaxation time significantly prolonged （P〈0.01） in the diabetic rats, which also exhibited a lowered tetanic force in response to stimulus （P〈0.01）. Transmission electron microscopy revealed obvious ultrastructural changes of the diaphragm in diabetic rats. RT-PCR showed significantly decreased SERCA and increased PLB mRNA expressions in diabetic rat diaphragm （P〈0.01）, and these changes intensified with time （P〈0.01）. Conclusions Diabetes can cause impairment of diaphragmatic ultrastructure, mitochondrial injuries, and lowered SDH activity and ATP production. Decreased SERCA and increased PLB mRNA expressions in diabetes result in reduced Ca^2＋ uptake by the diaphragm sarcoplasmic reticulum to induce diaphragm dysfunction.