蛋白质摄入量对肺气肿大鼠膈肌形态及功能的影响

Effect of dietary protein on the function and morphology of diaphragm in rats with experimental emphysema

为观察不同水平蛋白质摄入对肺气肿膈肌形态及功能的影响 ,将 5 0只SD大鼠随机分为 5组 ,每组 10只 ,2个对照组 (C1和C2 )大鼠注入生理盐水 ,3个实验组 (E、HP和LP组 )大鼠经气管一次注入弹性蛋白酶 75 0U kgBW制造肺气肿模型。 6周后处死C1和E组 ,HP组 (高蛋白组 )和LP组 (低蛋白组 )分别再给予 2 4%和 8%酪蛋白饲料 10周 ,C2组大鼠给予第四军医大学动物中心常备饲料。结果显示 ,E组肺总容量、平均肺泡面积显著增大 (P <0 0 5 ) ,符合肺气肿改变。E组膈肌收缩力增强 ,2 0Hz刺激的收缩力与最大收缩力之比 (F2 0 Fmax)增高 (P <0 0 1)。慢颤搐纤维横截面积增大 (P <0 0 1)。LP组膈肌收缩力显著降低 (P <0 0 5 )。提示肺气肿对膈肌功能、形态有显著影响。低蛋白饲料减低肺气肿大鼠膈肌收缩力 。

The effects of dietary protein on the function and morphology of diaphragm of rats with emphysema were observed in 50 SD rats, 10 rats in each group. The emphysema in groups E(emphysema control), HP(emphysema with high protein diet) and LP(emphysema with low protein diet) was induced by intra tracheal instillation of elastase (750 U/kg BW). The control rat (C1, C2) were instilled with normal saline. After 6 weeks of experiment, the total lung volume and the average area of alveolus was significantly increased in the group E compared with group C1 ( P <0 05) and the number of alveolus per unit area was also reduced obviously ( P <0 05). The average contractile force of diaphragm at a stimulus rate of 20Hz expressed as a ratio of the maximal contractile force (F20/Fmax) was increased significantly in group E compared with group C ( P <0 01). The cross sectional area of slow twitch fibers increased significantly in group E. After 10 weeks of oral supplementation with 24% casein(HP) or 8% casein (LP) to the rats with emphysema, the contractility of the diaphragm in group LP was lower than that in the control group and the HP group. It was concluded that high protein diet might be beneficial to maintain the function of diaphragm in patients with emphysema.