糖尿病大鼠膈肌功能和形态学变化

目的:观察四氧嘧啶诱导的糖尿病4周大鼠膈肌收缩功能和形态结构的改变。方法:应用体外大鼠膈肌肌条,对其单收缩动力学、最大强直张力(P₀)、张力-频率曲线、疲劳指数(FI)的变化以及应用H.E、Heidenhain铁矾苏木素法和标准脱氢酶染色法对膈肌组织的形态学变化进行观察。结果:糖尿病大鼠膈肌最大颤搐张力(Pt)、收缩时间(CT)、半舒张时间(RT_1/2)及FI均明显低于对照组,而两组P₀无明显变化。予25、50、75、100、125Hz频率刺激膈肌时,糖尿病大鼠膈肌张力明显低于对照组。在膈肌疲劳后予氨茶碱浸浴膈肌,再予25、50、75、100和125Hz频率分别刺激膈肌,糖尿病大鼠膈肌张力均明显低于对照组。H.E及Heidenhain法染色可见糖尿病大鼠膈肌萎缩,肌横纹模糊。标准脱氢酶染色法显示糖尿病大鼠膈肌α-甘油磷酸脱氢酶呈弱阳性,光密度明显低于对照组(P＜0.01)。结论:糖尿病4周大鼠膈肌出现收缩功能减弱、易疲劳和结构破坏。

Changes of diaphragmatic function and morphologic features in diabetic rats

AIM:To evaluate the changes of diaphragm contractile properties and morphologic features in experimental diabetic rats.METHODS:Diaphragm contractility was assessed by twitch kinetics,maximal tetanic force (P₀),tension-frequency relationship and fatigue index(FI)in vitro diaphragm strip preparations of 4th week diabetic Wistar rats,and compared with that of the control group.The structure of diaphragm was analysed in diabetic rats and control with Hematoxyline and eosin staining,Heidenhain staining and enzymatic histochemistry.RESULTS:The twitch (Pt),contraction time(CT),half relaxation time(RT_1/2)and FI decreased significantly in diabetic group as compared with the control group.There was no difference in Po between the two groups.The tension of diabetic diaphragm at frequencies of 25,50,75,100 and 125 Hz was significantly decreased compared with that of the normal rats.After diaphragm bundles were subjected to fatiguing stimulations and incubated with aminophylline at 250 mg/L for 30 minutes, the tension of diabetic diaphragm decreased remarkably at both high and low frequencies in comparison with that of the normal rats.In addition,the activity and optical density ofα-phosphoglycerol dehydrogenase in diaphragm from diabetic rats were significantly lower than that from control rats(P<0101).CONCLUSION:The reduction of contractile function,decreased diaphragm fatigue resistance,and damaged structure occurred in 4th week diabetic rat diaphragm.