动态增强MRI评估抗利尿激素缺乏大鼠肾功能的实验研究

Evaluation of kidney function in vasopressin-deficient rats by using dynamic enhanced MRI

目的探讨动态增强MRI检查判断抗利尿激素（AVP）缺乏大鼠梗阻肾功能及对AVP治疗的反应。方法3月龄Brattleboro（BB）鼠26只。其中建立单侧输尿管梗阻（UUO）模型12只，24h后解除梗阻。uu0和无梗阻鼠各7只行AVP治疗6d，无梗阻BB鼠和正常Wistar鼠各7只作为对照组。采用动态增强MRI检测肾皮质、髓质和肾盂的相对信号强度（RSI）和肾血流量（RBF）。结果1min时BB鼠肾皮质RSI峰值（149±10）％、髓质（155±13）％、肾盂（146±13）％，而后肾皮质RSI曲线缓慢下降，峰值明显低于Wistar鼠（P〈0．05）。AVP治疗后30S时BB鼠肾皮质、髓质和肾盂的RSI均升至（180±6）％，RSI曲线接近正常Wistar鼠RSI曲线。在UUO组肾髓质和肾盂RSI曲线较无梗阻组上升缓慢。uu0解除后，AVP治疗使梗阻鼠肾脏RSl变化曲线明显恢复，接近正常肾脏RSI变化曲线。uuO使RBF降至（1．1士0．1）ml·min^-1·100g^-1，注射AVP6d后RBF升至（1．9±0．3）ml·min^-1·100g^-1。结论BB鼠肾脏AVP治疗前后动态增强MRI的RSI曲线明显不同，提示MRI检查可以判断BB鼠梗阻肾功能及对AVP治疗的反应，为评估肾功能及区别肾脏是否梗阻提供重要信息。

Objective To evaluate the renal function response to vasopressin in obstructed and non-obstructed kidney in vasopressin-deficient rats by using dynamic enhanced MRI. Methods This study included 26 vasopressin deficient Brattleboro （BB） rats. Unilateral ureteral obstruction （UUO） model was set up in 12 BB rats. After releasing UUO 24 h, treatment of AVP was given in 7 non-obstructed and 7 obstructed BB rats for 6 d. Seven normal Wistar rats and 7 BB rats were used as control. Dynamic enhanced MRI was performed at 0--60 rain following the administration of Gadolinium- DTPA（0.05 mmol/kg） and the mean relative signal intensity （RSI）was measured. Results BB rats RSI increase occurred during the first minute, with a maximum mean RSI of （149±10）% in cortex, （155±13）% in medulla and （146±13）% in pelvis. Then, a gradual decrease in the cortical RSI occurred, after which a small increase was observed in Phase 3. BB rats RSI patterns were different from Wistar rats. After AVP treatment, mean RSI of BB rats in cortex, medulla and pelvis reached a maximum of （180±6）%, respectively at 30 sec, followed by a fast decrease at 1 min. Then, RSI decreased gradually. Phase 3 demonstrated a moderate increase in medullary and a relative large increase in pelvic RSI until 30 min after injection, after which RSI returned to baseline. BB rats RSI patterns after AVP treatment were similar to that of Wistar rats. Cortical, medullary and pelvic mean RSI increased slowly compared to non UUO rats. In phase 3, mean RSI of all segments decreased gradually. UUO rats RSI patterns were different from non UUO rats. After AVP treatment in UUO rats, mean RSIs of all segments increased faster compared to UUO rats without AVP. Cortical mean RSI reached a maximum of （193±7） % at 2 min. Mean RSI of medulla were unchanged, but the pelvic mean RSI decreased gradually to a minimum of （77±5）% at 5 rain. Phase 3 was characterized by a slight recovery of all RSIs. UUO rats RSIs were recovered after AVP treatment. The renal blood flow（RBF） of UUO rats was decreased to（1. 1±0. 1）ml·min^-1·100g^-1, wherease the RBF was increased to （1.9±0.3）ml·min^-1·100g^-1 after injecting AVP. Conclusion Dynamic enhanced MRI may provide useful information for distinguishing between kidneys having changes in the renal vasopressin concentration and the kidneys suffer from the obstructed renal damage.