诱导型一氧化氮合酶在缺血性急性肾衰竭肾小管损伤中的作用及L-精氨酸的疗效观察

The relations between iNOS and ischemic ARF,as well as the effect of extrinsic L-arginine on ARF.

目的研究急性肾衰竭(ARF)时诱导型一氧化氮合酶(iNOS)与肾小管损伤的关系及初步探讨L-精氨酸(L-arg)灌注对ARF的治疗作用。方法SD大鼠分为3组:①正常对照组(n=6),假手术;②ARF组(n=18),夹闭双肾动脉50min建立ARF模型;③ARF+L-Arg组(n=18),夹闭双肾动脉50min后,股静脉灌注L-Arg(300mg/kg)。通过内生肌酐清除率(Ccr)测定,肾脏病理学检查i、NOS免疫组化及改良NOS酶组化染色等方法观察iNOS在ARF小管损伤中的作用。结果术后1,3和5d Ccr值自术前(0.9978±0.149)L/d分别下降至(0.194±0.029)L/d、(0.21±0.126)L/d和(0.421±0.31)L/d,治疗组术后1,3和5d Ccr值分别为(0.294±0.056)L/d(、0.923±0.096)L/d和(1.126±0.21)L/d,与未治疗组同期相比有显著性差异(P<0.01)。生理状态下,iNOS在肾内表达较弱,ARF后1,3和5d肾内iNOS表达明显高于正常(P<0.05)。治疗组小管细胞iNOS表达明显减少(P<0.05)。小管细胞的空泡样变性、坏死、管型亦相应减少。结论ARF时局部缺血、低氧可迅速诱导肾小管上皮细胞的iNOS大量表达,这可能是引起小管损伤的重要因素之一。外源性L-Arg能减少小管细胞iNOS的表达,减轻ARF时的肾小管损伤。

Objective To investigate the relations between inducible nitric oxide synthase （iNOS） and tubular injury of acute renal failure （ARF）,as well as the effect of extrinsic L-arginine （L-arg） on ARF. Methods SD rats were divided into three groups： Control group （ n = 6 ） ： sham operation; ARF group （ n = 18 ） ： rats were subjected to 50 minutes of bilateral renal ischemia ; ARF ＋ L-arg group （ n = 18） ：an intravenous bolus of L-arg （300mg/kg） was given after releasing bilateral renal artery. In addition to measurement of creatinine clearance （Ccr）, histopathology, immunohistochemistry and enzyme histochemistry were performed with renal tissue of different groups. Results The Ccr value in ARF group decreased obviously from （0.9978 ± 0. 149 ） L/d to （ 0.194± 0. 029 ） L/d, （ 0.21 ± 0.126）L/d and （0.421 ± 0.31 ） L/d,respectively in the 1st,2nd and 5th day of post-operation （ P 〈 0.001） .The Ccr value at the 1st, 3rd and 5th day in ARF＋ L-arg group （0.294 ± 0.056L/d,0.923 ± 0.096L/d and 1.26 ± 0.21L/d,respectively） were much higher than those in ARF group （ P 〈 0.01 ）. However, a much extensive labeling pattern was observed in ARF group （P 〈 0.05 ）, including all kinds of tubule and vascular smooth muscle. Meantime expression of iNOS, vacuolar degeneration and necrosis of tubular epithelium reduced sharpiy in ARF ＋ L-Arg group compared with ARF group. Conclusion The results indicate that iNOS in tubular epithelium could be induced rapidly by ischemia and play an important role in tubular injury during ARF;Extrinsic L-arg could improve tubular injury in ARF by decreasing expression of iNOS in tubular epithelium.