烧伤后大鼠骨骼肌组织泛素及泛素化蛋白表达的变化研究

为研究烧伤大鼠骼肌组织泛素（ubiquitin)及泛素化蛋白表达的变化规律，探讨烧伤后骨骼肌蛋白降解的分子机制，采用大鼠30％Ⅲ度烫伤模型，分为伤后2、6、12和24h组，每组设正常对照组，于伤后不同时间点分别测定大鼠骨骼肌孵育液中伸趾长肌蛋白降解率以及伸趾长肌组织中泛素及泛素化蛋白的表达变化。结果发现，大鼠烧伤后伸趾长肌蛋白降解率增强，尤其是肌纤维蛋白降解增强明显（P＜0．01），伤后12h增加185％，24h增加153％；伸趾长肌泛素及泛素化蛋白的表达在烧伤后各时相点均显著增加（P＜0.01)，尤以12h和24h为明显，表达增加的泛素化蛋白主要为高分子量蛋白。提示烧伤后大鼠骨骼肌蛋白高分解代谢与泛素及泛素化蛋白的高表达关系密切。

STUDY ON THE CHANGES IN UBIQUITIN AND UBIQUITINATED PROTEIN IN RAT SKELETAL MUSCLE DURING POSTBURN PERIOD

To study the regularity of ubiquitin and ubiquitinated protein expression in rat skeletal muscle after burn injury, the molecular mechanism of skeletal muscle protein catabolism was investigated. Wistar rats were inflicted on a 30% full thickness burn. They were grouped according to the time of sacrifice :2, 6, 12 and 24 hours after burn, each group included normal control. The extensor digitorium logus (EDL) muscle was taken to assay the proteolytic rate and the expression of ubiquitin and ubiquitinated protein during postburn period. It was found that proteolytic rate of EDL muscle was markedly enhanced, especially in myofibrillar proteolytic rate, by 185% and 153% at 12h and 24h after burn injury, respectively. The contents of free ubiquitin and ubiquitinated protein in rat EDL muscle were significantly increased after burn injury, especially at 12 and 24 hour. The contents of free ubiquitin and ubiquitinated protein increased 33% and 186% at 12h postburn, increased 30% and 163% at 24h,respectively. The high protein catabolism of skeletal muscle during postburn stage is in close relation to high expression of free ubiquitin and ubiquitinated protein.