烫伤休克期切痂植皮对骨骼肌蛋白降解率影响的实验研究

目的　探讨严重烫伤休克期切痂的必要性。　方法　用大鼠 30 %Ⅲ度背部烫伤模型 ,观察大鼠严重烫伤后骨骼肌蛋白降解率的变化 ,以及实施休克期切痂前后骨骼肌蛋白分解的变化。大鼠随机分为烫伤组、休克期切痂组和非休克期切痂组 3组 ,每组 5个时间点 (含伤前对照 )每时间点8只大鼠。两切痂组分别于伤后 1d和 4d切痂植皮 ,采用无创技术和骨骼肌充分氧供离体孵育系统测定伸趾长肌蛋白降解率。　结果　烫伤后 1d伸趾长肌总蛋白降解率较伤前显著增加 (t=2 988～3 12 4均P <0 0 1) ,差异均有非常显著意义 ;余时间点变化不明显 ,烫伤组、休克期切痂组和非休克切痂组相比差异无显著性意义。然而伸趾长肌肌纤维蛋白降解率在烫伤后各时间点均较伤前值显著增加 (均t=2 977～ 4 72 5 ,P <0 0 1) ,差异均有非常显著性意义。休克期切痂组组较大休克切痂组在伤后 2、4、5d显著降低 (tz=2 311,P <0 0 5 ;t4,5=3 0 5 4 ,3 319,P <0 0 1) ,差异均有显著和非常显著性意义 ;其中休克期切痂组伸趾长肌肌纤维蛋白降解率均值分别为每 3h 3 17、2 33、1 75nmol/g。两切痂组比较差异无显著意义 ,仅在伤后 5d轻度下降。结论　休克期切痂有助于减轻烫伤后骨骼肌蛋白的高分解代谢反应。

The influence of escharectomy during shock stage on skeletal muscle proteolytic rate in severely scalded rats

Objectives To observe the changes in proteolytic rate and the influence of escharectomy and skin grafting during shock stage on the proteolytic rate of skeletal muscle in severely scalded rats, and to investigate necessity of escharectomy during shock stage Methods Wistar rats affilicted with 30%TBSA(total body surface area) full thickness burn on the back were randomly divided into 3 groups: burn injury group (group B), escharectomy during shock stage group (group S), and escharectomy after shock stage group (group N) Escharectomy and skin grafting was performed on the postburn day1(PBD1) and PBD4 in group S and N The extensor digitorium longus (EDL) muscle was collected using a technique without injury to the muscle, and the proteolytic rate of the EDL was determined by the in vitro muscle incubation system with sufficient oxygen supply and amino acid automatic analyzer Results The total proteolytic rate (TPR) in rat EDL muscles increased significantly( t> 2 988, P< 0 01) on PBD1, but no prominent changes were observed at other time points. There were no statistically significant changes in TPR between group S and group N, but the myofibrillar proteolytic rate (MPR) in rat EDL muscles increased markedly at each time point after scald( t> 2 988, P< 0 01). The MPR in group S decreased significantly as compared with that in group N on PBD2,4,5( t= 2 311, P< 0 05; t= 3 054, 3 319, P< 0 01),and the mean values were 3 17, 2 33, 1 75 nmol/wet weight in g/3 h, respectively No significant changes were observed between group N and S Conclusion The high protein catabolism of skeletal muscle can be alleviated by escharectomy and skin grafting during shock stage, and it is beneficial to organics.