中文摘要：

目的探讨支气管肺泡腔等细胞外液中是否存在泛素蛋白酶体及其在急性肺损伤过程中的变化和作用机制。方法应用大鼠肺挫伤模型研究急性肺损伤支气管肺泡腔内泛素蛋白酶体含量变化及其可能的病理生理作用。分别采用生化检测、酶联免疫吸附试验（ELISA）及Westernblot等方法研究对照组及急性肺损伤组伤后6～168h支气管肺泡灌洗液（BALF）中蛋白酶体20S亚基、泛素等含量及其活性。结果急性肺损伤后其BALF中20S蛋白酶体、泛素含量明显增加，在24h达到峰值（20S：（2397±71）μg／L；泛素（469±124）μg／L），168h恢复至正常水平（20S：（42±30）μg／L；泛素（31±6）μg／L）。BALF中ATP／Mg2＋依赖的多肽酶Epoxomiein敏感的胰凝乳蛋白酶样（CT-L）及Epoxomicin敏感的胰蛋白酶样（T—L）酶活性在肺挫伤后6—24h明显增加，两者均在伤后24h增高到峰值[CT—L：（3621±245）pmol／（h·m1）；T—L：（736±91）pmol／（h·ml）]。在急性肺损伤的BALF中加入ATP／Mg“可导致蛋白质降解明显增加，但加入Epoxomiein或乙二胺四乙酸（EDTA）可显著抑制蛋白质降解。结论蛋白酶体存在于细胞外液；在急性肺损伤后，蛋白酶体释放进入细胞外支气管肺泡腔中，在肺泡蛋白质降解、廓清过程中起重要作用。

英文摘要：

Objective To explore the presence and role of ubiquitin-proteasome-pathway （UPP） in the bronchoalveolar space of the injured lung. Methods A rat model of lung contusion （LC） was used to evaluate the pathophysiological role of UPP in the injured lung. Fifty SD rats were divided into control groups and lung contusion group （LC）. Bronehoalveolar lavage fluids （BALF） were obtained at different time points up from 6 h to 168 h after LC or control groups. The concentration of protein, enzyme activi- ties, enzyme linked immunosorbent assay （ELISA） and Western blotting were used to evaluate the UPP in the BALF. Results The data indicated the presence of ubiquitin and proteasomes in BALF, 20S and ubiquitin were increased significantly after LC, peaked at 24 h [ 20S： （2397 ＋ 71 ） μg/L; ubiquitin （469 ＋ 124） p,g/L] and normalized at 168 h [20S： （42 ＋30） μg/L; ubiquitin （31 ＋6） p.g/L） after LC. Mg2＋/ATP-dependent peptidase activities were detected 6-24 h in BALF afer LC, and peaked at 24 h [ CT-L： （3621 ＋ 245） pmol × h-1 × mL- t ; T-L： （736 ＋ 91 ） pmol x h-1 x mL-＇ ）. Addition of Mg2＋/ ATP in BALF accelerated the proteolysis, which could be prevented by Epoxomicin and EDTA. Conclusion The UPP exists in the extracellular space. The proteasomes is released in BALF after LC, which may play an important role in injured lung.