摘要目的 观察正常血压衰老和高血压衰老大鼠肾皮质血管紧张素Ⅱ(AngⅡ)及肾小球足细胞自噬的变化,探讨高血压衰老时肾损伤的可能机制. 方法 正常血压大鼠Wistar-Kyoto(WKY)分为3、13、22月龄组,均有性别、月龄、数量相匹配的自发性高血压大鼠(spontaneously hypertensive rat SHR)为对照.监测大鼠血压;检测尿蛋白、尿肌酐、血肌酐、血尿素、血清和肾皮质AngⅡ水平;观察肾组织光镜、透射电镜下形态学改变,计数足细胞内自噬体;检测肾小球nephrin、LC3BⅡ、Atg5、p62表达情况. 结果 SHR血压高于WKY(P＜0.05);正常血压和高血压衰老时,尿蛋白/尿肌酐比值均升高[WKY:3月龄组(0.12±0.01) g/mmol,13月龄组(0.14±0.04) g/mmol,22月龄组(0.34±0.05) g/mmol,P＜0.05;SHR:3月龄组(0.29±0.04) g/mmol,13月龄组(0.31±0.05)g/mmol,22月龄组(0.72±0.16)g/mmol,P＜0.05],但血肌酐、血尿素均无变化(均P＞0.05);正常血压、高血压衰老、老时血清和肾皮质AngⅡ水平无变化(均P＞0.05),但肾皮质AngⅡ水平下降[SHR3月龄组(0.02±0.00)μg/L,13月龄组(0.02±0.00)μg/L,22月龄组(0.01±0.00)μg/L,P＜0.05];正常血压、高血压衰老时肾脏均出现肾小球硬化、肾小管萎缩和间质纤维化等衰老病变,但以高血压衰老时病变更为严重;正常血压衰老时肾小球足细胞自噬体相对堆积;肾小球LC3BⅡ、Atg5、p62蛋白表达增多(均P＜0.05),而高血压衰老时肾小球nephrin、LC3BⅡ、Atg5、p62蛋白表达减少(均P＜0.05). 结论 高血压衰老时肾皮质AngⅡ水平下降;正常血压衰老时肾小球足细胞自噬活性相对下降,高血压衰老时肾小球足细胞自噬活性相对升高,高血压衰老时肾损伤可能与AngⅡ诱导肾小球足细胞自噬有关.

abstractsObjective To study the changes of renal cortex angiotensin Ⅱ (AngⅡ) expression and podocyte autophagy in aging rats with normotension versus hypertension,to further investigate the possible mechanism of renal injury in hypertension during aging.Methods Normotensive Wistar-Kyoto-rats (WKYs) were allocated to three groups by age of 3-month-old group,13-month-old group,22-month-old group.Gender,age and number-matched spontaneously hypertensive rats (SHRs) served as controls.Blood pressure was monitored.Levels of urinary albumin,urinary creatinine,serum creatinine (SCR),blood urea nitrogen (BUN),Ang Ⅱ in serum and in renal cortex were detected.The kidney ultrastructural changes and podocyte autophagosomes were observed under light and transmission electron microscopy.Expressions of nephrin,LC3B Ⅱ,Atg5 and p62 in glomeruli were analyzed by Western blotting.Results Blood pressure was significantly higher in SHRs than in WKYs (P＜0.05).During aging from 3-month-old to 13-month-old and to 22 monthold group,the urinary albumin/creatinine ratio was increased significantly in SHRs with hypertension and in WKYs with normotension [WKY:(0.12±0.01) g/mmol,(0.14±0.04) g/mmol vs.(0.34± 0.05) g/mmol;in SHR:(0.29±0.04) g/mmol,(0.31±0.05) g/mmol vs.(0.72±0.16) g/mmol,P＜0.05],but SCR and BUN levels had no significant difference in SHRs and WKYs during aging (both P＞0.05).And Ang Ⅱ levels in both serum and renal cortex had no significant change in normotension group during aging three time points (both P＞0.05).An age-dependent decrease of Ang Ⅱ level in renal cortex appeared during aging three time points in hypertensive rats [SHR:(0.02 ±0.00) μg/L,(0.02±0.00) μg/L vs.(0.01±0.00) μg/L,P＜0.05],but serum level of Ang Ⅱ had no significant difference during aging three time points (P＞ 0.05) in hypertension group.The structural changes,including glomerulosclerosis,tubular atrophy and interstitial fibrosis were observed during aging three time points both in normotensive and hypertensive rats,but these pathological changes were more serious in hypertensive rats.Autophagosomes relatively accumulated in aging normotensive rats.The protein expressions of LC3B Ⅱ,Atg5 and p62 were increased in normotensive rats during aging (all P＜0.05).While the protein expressions of nephrin,LC3B Ⅱ,Atg5 and p62 were decreased in aging hypertensive rats (all P ＜ 0.05).Conclusions Ang Ⅱ expression level in renal cortex is decreased during aging in hypertensive rats.Podocyte autophagic activity is relatively decreased during aging in normotensive rats,but is relatively increased during aging in hypertensive rats.Ang Ⅱ-induced podocyte autophagy may be involved in the pathogenesis of renal injury in hypertension during aging.