内皮素1和血管紧张素Ⅱ在过度训练致大鼠急性肾损伤中的作用

The role of endothelin-1 and angiotensin Ⅱ in acute kidney injury due to over-exertion in rats

目的观察大鼠力竭后不同时期血浆及肾组织中内皮素1(ET-1)和血管紧张素Ⅱ(AngⅡ)的变化及其与肾损伤的关系,探讨ET-1和AngⅡ在过度训练致急性肾损伤(OTIAKI)中的作用。方法健康雄性Wistar大鼠40只随机分为对照组(n=8)和力竭组(ES,n=32)。ES组又根据力竭后恢复时间分为力竭后即刻(ESI)组、ES6h组、ES12h组和ES24h组,每组8只大鼠。采用大鼠游泳至力竭建立过度训练模型,而对照组大鼠未进行力竭运动。各组于力竭后即刻,6、12、24h分别检测各组大鼠血清尿素(Ur)、肌酐(Cr)水平;光镜观察肾组织结构改变;采用TUNEL法检测各组大鼠肾组织细胞凋亡;放射免疫分析法测定血浆和肾组织ET-1和AngⅡ含量,并分析力竭大鼠血浆及肾组织ET-1与血清Ur、Cr的相关性及肾组织AngⅡ与肾组织细胞凋亡率之间的相关性。结果力竭即刻大鼠血清Ur、Cr明显升高(P<0.05),6h达高峰(P<0.05),24h恢复到对照水平。力竭后即刻、6、12、24h大鼠肾组织结构变化轻微,但逐渐加重。力竭后即刻至24h大鼠肾细胞凋亡率呈进行性升高(P<0.01)。力竭后大鼠血浆ET-1和AngⅡ均明显升高(P<0.01),于力竭即刻AngⅡ达高峰(P<0.01),之后则逐渐降低,至24h恢复至对照组水平;而ET-1于力竭后6h达高峰(P<0.01),至24h恢复至对照组水平。肾组织ET-1的变化趋势与血浆ET-1平行,而肾组织AngⅡ于力竭后即刻至24h则呈进行性增高(P<0.01)。力竭大鼠血浆及肾组织ET-1含量与血清Ur和Cr均呈明显的正相关(P<0.001),肾组织AngⅡ含量与肾组织细胞凋亡率呈明显正相关(P<0.01)。结论过度训练大鼠血液循环中ET-1和AngⅡ的升高主要参与力竭后早期肾损伤的发生;在OTIAKI早期,肾组织ET-1比AngⅡ发挥更重要的作用;而在OTIAKI的维持期,肾组织AngⅡ比ET-1发挥更重要作用。

Objective % study the role of endothelin-1 （ET1） and angiotensin Ⅱ （Angl]） in over-exertion induced acute kidney injury （OTIAKI） by observing the changes in ET-1 and Angll contents in plasma and renal tissue and their relationship with OTIAKI in exhausted rats. Methods 40 male Wistar rats were randomly divided into two groups： control group （CN, n=8） and exhaustion group （ES, n=32）. The exhaustion group, depending on the recovery time after exhaustion, was further divided into 4 subgroups （8 each） ： immediate subgroup （ESI）, 6h after exhaustion subgroup （ES 6h）, 12h after exhaustion subgroup （ES 12h） and 24h after exhaustion subgroup （ES 24h）. The animal model of OTIAKI was reproduced by exhausting swimming, while the rats in control group were not forced to swim. The contents of serum urea （Ur） and creatinine （Cr） in each group were serially measured. The renal specimens were observed with a light microscope to study their morphologic changes. Renal cell apoptosis was detected using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling （TUNEL） assay. The contents of ET-1 and AngⅡ in plasma and renal tissue were measured by radio-immunoassay （RIA）. The correlation between the content of ET-1 and the levels of serum Ur and Cr were was analyzed by Pearson method, and the correlation between the content of AngⅡ in renal tissue and cell apoptosis was analyzed by Spearman method. Results The levels of serum Ur and Cr were significantly increased in ESI group （P〈0. 05）, and further increased in ES 6h group （P〈0. 05）, and returned to that of CN group in ES 24h group. There were slight changes in renal structure in ES subgroups after exhaustion. TUNEL revealed that the number of apoptotic cell was increased in kidney of rats at ESI to ES 24h after exhausting swimming. Radio-immunoassay showed that ET1 and AngⅡ levels in plasma were significantly increased in ES subgroups, and that of AngⅡ reached the highest level at ESI and ET-1 at ES 6h （P〈0. 01）, then decreased gradually, returning to that of CN at ES 24h. The changes in ET-1 in renal tissue were similar to ET-1 in plasma, but the AngⅡ in renal tissue was continuously increased significantly from ESI group to ES24h group （P〈 0.01）. There was a significant and positive correlation between the content of ET-1 in plasma and renal tissue and the value of serum Ur and Cr （P〈0. 01）, and also a positive correlation between the AngⅡ in renal tissue and apoptosis rate of renal cells （P〈0. 01）. Conclusion The increased ET-1 and AngⅡ in blood circulation may play a major role in the pathogenesis of initial phase of OTIAKI. The role of ET- 1 in renal tissue might be more important in the early phase of OTIAKI than AngⅡ; and AngⅡ in renal tissue may play more important role in the sustaining stage of OTIAKI than ET-1.