大鼠肢体缺血-再灌注后肾脏iNOS表达的变化及意义

Changes of iNOS gene expression in kidney following ischemia and reperfusion of limbs and their significance in rats

目的 :探讨大鼠肢体缺血 -再灌注 (I-R)致肾脏损伤时肾内iNOS表达的变化及意义。方法 :夹闭、再开放大鼠双侧股动脉 ,复制肢体I-R模型。RT -PCR检测肾组织iNOSmRNA表达的变化 ;免疫组化染色法观察iNOS蛋白及硝基酪氨酸 (NT)在肾内的生成及分布 ;比色法测定肾组织MDA含量及SOD活性 ;应用氨基胍抑制大鼠体内iNOS活性后观察其肾组织的病理学变化。结果 :肢体I -R后肾内iNOSmRNA表达显著高于对照组 (P <0 0 1) ,肾小管上皮细胞内出现大量iNOS及NT阳性产物 ;肢体I-R后肾组织MDA含量显著升高 ,SOD活性显著降低 (P <0 0 1) ;应用氨基胍后肾组织损伤减轻。结论 :肢体I -R后肾内iNOS表达显著上调 ,由其诱生的高浓度NO可能参与介导了肾脏损伤。

AIM: To detect the changes of inducible nitric oxide synthase (iNOS) expression in kidney following ischemia-reperfusion(I-R)of hindlimbs and to elucidate their significance. METHODS: I-R was established using the occlusion of the femoral arteries for 4 h and re-opening for 2-24 h in rats. The expression of iNOS mRNA,and iNOS protein and the nitrotyrosine (NT),a marker of peroxynitrite (ONOO -),in renal tissue were detected with reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical technique,respectively. The superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in renal tissue were spectraphotometrically measured. The observation of pathologic changes of renal tissue was made following the inhibition of iNOS by aminoguanidine (AG). RESULTS: Compared with control group,the relative expression level of iNOS mRNA significantly increased in I-R group. There were more iNOS and more NT positive product in the epithelial cells of renal proximal convoluted tubules and thick segments of Henle′ loops in I-R group than control group. The contents of MDA markedly increased,while the activity of SOD significantly decreased in I-R group,compared to those in the control groups. The pathologic changes of kidney became milder in I-R group following the inhibition of iNOS by AG. CONCLUSION: The expression of iNOS mRNA and protein in renal tissue were significantly upregulated,excess induction of NO contributed to the kidney injury during the I-R of hindlimbs.