左旋精氨酸预处理对老龄大鼠肾缺血再灌注损伤的保护作用

Protective Effect on Renal Ischemia-reperfusion Injury in Aging Rats after L-arginine Preconditioning

目的研究左旋精氨酸（L-arginine，L-Arg）对老龄大鼠肾缺血再灌注损伤（ischemia-reperfusioniNury，IRI）的保护作用并探讨其作用机制。方法将SD大鼠分为3组，L-Arg组大鼠构建IRI模型，手术前24h及术前30min尾静脉注射左旋精氨酸，剂量为250mg／kg；IR组大鼠构建IRI模型，仅注射生理盐水；对照组（C组）为分离肾蒂血管，注射生理盐水。观察大鼠IR后生存时间，另分别于再灌注后4、8、12、24、48、72h处死动物，处死前下腔静脉取血，检测血肌酐（serumcreatinine，Scr）和尿素氮（bloodureanitrogen，BUN）水平。获取肾组织标本，用于髓过氧化物酶（my-eloperoxidase，MPO）酶联免疫吸附剂测定（enzyme-linkedimmunosorbentassay，ELISA）检测，免疫组化和Westernblot检测血红素氧化酶-1（hemeoxidase-1，HO-1）含量，以及病理学观察。结果①IR组存活率为37．5％，L_Arg组大鼠存活率提高至70．8％，而对照组大鼠存活率100％，各组之间有明显差异（P〈0．01）。②IR组大鼠再灌注后4h时Scr和BUN水平开始逐渐升高，与C组相比，IR组Scr和BUN在各个时间段明显升高（P〈0．01），再灌注后4～72h，L-Arg组大鼠Scr均较IR组明显降低（P〈0．01）。③单纯IR组大鼠再灌注后4h开始升高，各时间点肾组织MPO水平均高于C组（P〈0．01）和L-Arg组，且在再灌注后12，24，72h最显著（P〈0．01）。④免疫组化和Westernblot结果显示：L-Arg预处理后，肾组织中HO-1阳性细胞数量增加，L-Arg组大鼠肾脏组织HO-1表达水平明显高于IR组（P〈0．05）。结论L-Arg预处理能够改善老龄大鼠肾功能，减轻肾组织病理损伤，减少再灌注后炎症反应，提高大鼠肾缺血再灌注后生存率。L-Arg通过诱导HO-1的表达可以保护老龄大鼠肾脏的缺血再灌注损伤。

Objective To investigate the effect and the protective mechanism of L-arginine （L-Arg） on renal ische- mia-reperfusion injury （IRI） in aging rats. Methods Rats were randomly separated into control group （group C）, IRI group （group IR） and L-arginine group （group LArg ）. In groups IR and L-Arg,the renal IRI model was established. L- arginine was injected through the tail vein in group L-Arg, and the equal volume of saline was injected in group IR. The kidney pedicle was separated and saline was injected in group C. Rats were sacrificed at 4,8,12,24,48 and 72 hours after ischemia-reperfusion （IR）. The levels of serum creatinine （Scr） and blood urea nitrogen （BUN）, the activity of myeloper- oxidase （MPO） were measured. The histopathological lesions were observed in renal tissues after 24 hours of IR. Western blot and immunohistochemistry were used to detect the levels of hemeoxidase-1 （HO-1） protein in renal tissues after 24 hours of IR. Results Survival rate of rat in group IR was 37. 5%,70. 8% in group L-Arg and 100% in group C, which were significantly different （P〈0. 01）. The levels of Scr and BUN in groups IR and L-Arg were higher than those in group C at 4 hours after IR （P〈0. 01）. At 4-72 hours after IR, the levels of Scr in group L-Arg were lower than those ingroup IR （P〈0. 01）. At 4 hours after IR, the levels of MPO was significantly increased and higher at all timepoints in group IR than those in group C （P〈0. 01） and group L-Arg （P〈0. 01）. The number of HO-1 posi- tive cells increased after L-arginine preconditioning, and HO-1 protein expression in group L-Arg was higher than that in group IR （P〈0. 05）. Conclusion L-arginine canimprove renal function alleviate pathological injury of kidney tissue and decrease inflammatory reaction. L-arginine can protect the kidney of aging rats against IRI significantly, which may be due to the up-regulated expression of hemeoxygenase-l.