Molecular mechanisms of ischemia/reperfusion-induced renal injury

(1)：为了探讨rho激酶在缺血性急性肾功能衰竭（ARF）发病机制中的作用，我们检测了选择性rho激酶抑制剂Y-27632对缺血/再灌注诱导的ARF的影响。Y-27632明显抑制缺血再灌注（I/R）诱导的ARF的发生，其作用与抑制中性粒细胞浸润有关，提示Rho/Rho激酶通路在缺血性ARE发病机制中起关键作用。(2)：我们评估了新型选择性Na^+/Ca^<2+>交换（NCX）抑制剂SEA0400对缺血性ARF的作用，SEA0400剂量依赖性地减轻了I/ r诱导的肾功能障碍和组织学损害。接下来，我们利用NCX^< 2+ /->杂合小鼠，通过NCX的反向模式研究Ca^<2+>过载在I/ r诱导的肾损伤中的病理生理作用。与野生型小鼠相比，杂合小鼠I/ r诱导的肾功能障碍明显减弱。杂合子小鼠肾组织损伤明显小于野生型小鼠。野生型小鼠肾内皮素-1含量的增加高于杂合型小鼠。这些发现有力地支持了Ca^<2+>通过NCX的反向模式过载，随后是肾内皮素-1的过量产生，在I/ r诱导的肾损伤的发病机制中起重要作用的观点。此外，SEA0400等选择性NCX抑制剂有可能作为缺血性ARF的有效治疗剂。(3)：研究了一氧化氮（NO）供体FK409对I/ r诱导的ARE的影响。FK409缺血前处理通过抗氧化作用和降低内皮素-1的产生显著抑制肾损害。相反，缺血后用FK409治疗加重了I/ r诱导的肾功能障碍和组织学损害。免疫组织化学分析ARE大鼠肾切片显示，损伤小管细胞中硝基酪氨酸（一种过氧亚硝酸盐形成的生物标志物）呈阳性染色，FK409缺血后的动物肾组织中染色更强烈。这些结果表明，尽管用NO供体进行缺血前治疗具有肾保护作用，但用相同的药物进行缺血后治疗可能会加重I/ r诱导的肾损伤，这可能是通过过氧亚硝酸盐过量产生的。少

(1) : To investigate the role of Rho-kinase in the pathogenesis of ischemic acute renal failure (ARF), we examined the effect of Y-27632, a selective Rho-kinase inhibitor, on the ischemia/reperfusion-induced ARF. Y-27632 markedly suppressed the development of ischemia/reperfusion (I/R)-induced ARF and the effects was related to the suppression of neutrophil infiltration, thereby suggesting that the Rho/Rho-kinase pathway plays a key role in the pathogenesis of ischemic ARE.(2) : We evaluated the effects of SEA0400, a novel and selective Na^+/Ca^<2+> exchange (NCX) inhibitor, on ischemic ARF SEA0400 dose-dependently attenuated the I/R-induced renal dysfunction and histological damage. Next, using NCX^<+/-> heterozygous mice, the pathophysiological role of Ca^<2+> overload via the reverse mode of NCX in I/R-induced renal injury, was investigated. I/R-induced renal dysfunction in heterozygous mice were significantly attenuated compared with cases in wild-type mice. Histological renal dama … More ge in heterozygous mice was much less than that in wild-type mice. Increases in renal endothelin-1 content were greater in wild-type than in heterozygous mice. These findings strongly support the view that Ca^<2+> overload via the reverse-mode of NCX, followed by renal endothelin-1 overproduction, plays an important role in the pathogenesis of I/R-induced renal injury. In addition, the possibility exists that a selective NCX inhibitor such as SEA0400 is useful as effective therapeutic agent against ischemic ARF.(3): Effects of nitric oxide (NO) donor, FK409, on the I/R-induced ARE were investigated. The pre-ischemic treatment with FK409 markedly suppressed the renal lesion by the antioxidative action and decreasing endothelin-1 production. In contrast, the post-ischemic treatment with FK409 aggravated the I/R-induced renal dysfunction and histological damage. Immunohistochemical analysis of renal sections obtained from ARE rats revealed positive staining for nitrotyrosine, a biomarker of peroxynitrite formation, in injured tubular cells, and more intense staining was observed in renal tissues from animals received post-ischemic treatment with FK409. These results demonstrate that, although pre-ischemic treatment with NO donor is renoprotective, post-ischemic treatment with the same agent aggravates the I/R-induced renal injury, probably through the peroxynitrite overproduction. Less