急性缺血再灌注损伤对肾脏的近期和远期作用

目的 探讨急性缺血再灌注（IR）损伤对大鼠肾脏的近期和远期作用及其机制。 方法 双侧肾蒂夹闭40 min后再灌注，制作大鼠IR模型。术后4 h、24 h、48 h、72 h、1周、5周和10周收集血样和肾脏标本，动态观察肾脏病理、肾功能和大鼠死亡情况。用透射电镜观察小管上皮细胞的超微结构；原位末端标记法（TUNEL）检测肾小管上皮细胞凋亡情况；Masson染色法观察小管间质纤维化程度；Western印迹法测定α?鄄平滑肌肌动蛋白(α-SMA)表达；免疫组织化学法观察肾脏α-SMA和转化生长因子β1 (TGF-β1)的分布和表达。 结果　 再灌注后IR组的Scr 和BUN水平逐渐升高，48 h达到最高峰。IR组病死率为32% (8/25)，假手术（Sham）组病死率为0 (0/22)。再灌注48 h IR组出现近端肾小管上皮细胞广泛性坏死和少量凋亡；IR组术后5周和10周有轻至中度的小管间质纤维化，术后1周肾脏α-SMA和TGF-β1蛋白表达显著升高，以后两者表达有所下降但仍高于Sham组。 结论 严重的缺血再灌注损伤不仅是早期肾小管大量坏死、肾功能急剧下降和病死率增高的原因，而且可以导致小管间质纤维化，影响肾脏的远期预后。TGF-β1过表达和肌成纤维细胞增多可能介导了纤维化病变。

Short-and long-term outcome of the kidney after acute ischema-reperfusion injury

Objective To investigate short- and long-term outcome of the kidney after acute ischemia-reperfusion (IR) injury. Methods Rat model of renal IR was established with clamping both pedicles for 40 min followed by reperfusion. Blood sample and kidneys were collected at indicated times. Serum creatinine levels, mortality and histological change were observed throughout the study. Transmission electron microscopy (TEM) was used to observe tubular ultra-structure. Apoptosis was confirmed by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) assay. The extent of tubulointerstitial fibrosis was evaluated by Masson trichrome staining. The expression of α-smooth muscle actin (α-SMA) and transforming growth factor-β1(TGF-β1) was determined by Western blot and immunohistochemical analysis. Results Extensive proximal tubular necrosis, functional impairment and high mortality (32%, 8/25) were found in the early phase after renal IR injury, accompanied by a small number of apoptotic cells. Patchy tubulointerstitial fibrosis was obvious at 5th and 10th week postischemia, in correlation with renal hypertrophy and increased urinary output. Moreover, the expression of α-SMA and TGF-β1 increased significantly at first, 5th and 10th week in the kidneys of IR group compared to sham-operated group. Above expression was localized mainly in the injured tubulointerstitium, consistent with the distribution of renal fibrosis. Conclusions Severe renal IR injury may lead to acute tubular necrosis, functional disorder and high mortality in short term. The initial structural injury in the kidney is irreversible and tubulointerstitial fibrosis is the final outcome. Increased myofibrolasts (α-SMA positive) and overexpression of TGF-β1 maybe contribute to the process of tubulointerstitial fibrosis.