Molecular mechanisms of ischemia/reperfusion-induced renal injury

(1)：为探讨Rho-K在缺血性急性肾功能衰竭发病机制中的作用，我们观察了选择性Rho-K抑制剂Y-27632对缺血/再灌注性急性肾功能衰竭的影响。Y-27632显著抑制缺血/再灌流诱导的急性肾功能衰竭，其作用与抑制中性粒细胞浸润有关，提示Rho/Rho-Kinase通路在缺血肾损伤的发病机制中起关键作用。(2)：我们评价了新型选择性Na~+/Ca~(2+)交换(Ncx)抑制剂SEA0400对缺血/再灌流所致肾功能障碍和组织学损伤的影响，并呈剂量依赖关系。接下来，利用NCX^&lt；+/-&gt；杂合子小鼠，研究了钙超载通过逆转NCX模式在肾I/R损伤中的病理生理作用。与野生型小鼠相比，杂合子小鼠的I/R引起的肾功能障碍显著减轻。组织学肾损害…杂合子小鼠的GE显著低于野生型小鼠。野生型小鼠肾脏内皮素-1含量的增加比杂合子小鼠更大。这些结果有力地支持了这样一种观点，即通过NCX的反向模式的钙超载，继而导致肾脏内皮素-1的过度产生，在I/R所致的肾损伤的发病机制中起着重要作用。此外，选择性NCX抑制剂如SEA0400有可能成为治疗缺血性ARF的有效药物。(3)：观察一氧化氮(NO)供体FK409对缺血再灌流(I/R)诱导的ARF的影响。缺血前应用FK409可明显抑制肾损害，其机制可能与抗氧化作用和减少内皮素-1的产生有关。相反，FK409缺血后治疗加重了I/R所致的肾功能障碍和组织学损害。对ARE大鼠肾脏切片的免疫组织化学分析显示，在受损的肾小管细胞中，硝基酪氨酸(过氧亚硝酸盐形成的生物标志物)呈阳性染色，而在接受FK409缺血后治疗的动物的肾组织中，观察到更强的染色。这些结果表明，尽管缺血前给予NO供体具有肾脏保护作用，但缺血后给予相同的药物可加重I/R所致的肾损伤，可能是通过过量产生过氧亚硝酸盐来实现的。较少

(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