老年大鼠肾脏微分离肾小球、肾小管及动脉血管紧张素Ⅱ受体的表达

Gene expression of angiotensin Ⅱ receptors in isolated glomeruli, tubules and arteries of aged rats

目的 :观察老年大鼠肾脏不同部位不同亚型的血管紧张素Ⅱ受体 (ATR)基因表达的改变。方法 :取 3月龄及 2 4月龄雄性Wistar大鼠肾脏 ,行Western印迹杂交及Northern印迹杂交检测肾皮质AT1R的蛋白及基因表达 ,行冰冻切片 (厚 5 μm) ,通过激光切割、弹射微分离系统分离肾小球、肾小管及动脉 ,提取RNA ,利用RT -PCR方法观察AT1aRmRNA、AT1bRmRNA及AT2 RmRNA的表达。结果 :2 4月龄大鼠肾脏的AT1R在蛋白水平及基因水平均低于 3月龄大鼠。应用自动激光微分离技术成功分离了大鼠肾脏的肾小球、肾小管及小动脉。 2 4月龄大鼠肾小球AT1aRmRNA的表达与 3月龄大鼠比较无明显差异 ,在肾小管表达低于 3月龄大鼠 ,动脉表达高于 3月龄大鼠 ;AT1bRmRNA在肾小球、肾小管表达均低于 3月龄大鼠 ,在动脉的表达高于 3月龄大鼠 ;AT2 RmRNA的表达在肾小管明显高于 3月龄大鼠 ,在肾小球及动脉的表达无明显差异。结论 :老年大鼠的肾小球、肾小管及肾内动脉各型血管紧张素受体的改变不同 ,有可能在肾脏增龄性改变中起重要作用。

AIM: To investigate the effects of aging on the angiotensinⅡ receptors (ATR) in different parts of the kidney. METHODS: Expression of AT 1 receptor in renal cortex was determined by Western and Northern blotting. Five micrometer thick cryostat sections of 3 or 24-month Wistar rats were mounted onto a 1.35μm thin polyethylene membrane. Glomeruli, tubules and arteries of rat kidney were isolated by laser microdissection and pressure catapulting system, AT 1aR mRNA, AT 1bR mRNA AT 2R mRNA were measured with reverse-transcription PCR(RT-PCR). RESULTS: Western and Northern blotting showed that protein and gene expression of AT 1 receptor in kidney cortex decreased in 24 month Wistar rats compared to those in 3 month Wistar rats. Glomeruli, tubules and arteries were quickly isolated by laser microdissection and pressure catapulting system without contamination. Compared to young group, AT 1aR mRNA expression was decreased in the tubules of aged rats, no changes was found in isolated glomeruli. AT 1bR mRNA was decreased in glomeruli and tubules. Both AT 1aR mRNA, AT 1bR mRNA were increased in the arteries. AT 2R mRNA was only increased in the tubules, whereas there were no significant changes in the glomeruli or arteries. CONCLUSION: Angiotensin Ⅱ receptors are regulated selectively in different portions of aged kidney, which might play an important role in aging related changes of the kidney.