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目的 探讨外源性血管紧张素 (Ang- )对老年大鼠 (1 9～ 2 2月龄 )皮层肾小球和肾小管的效应。方法 利用活体微穿刺技术。结果 在基础状态下 ,老年大鼠比年轻大鼠 (4～ 5月龄 )肾小球血压 (PGC)高。在注射外源性 Ang- 时 ,老年大鼠和年轻大鼠都出现显著血压升高和肾血管收缩。对年轻大鼠 ,不改变肾小球滤过率 (GFR)和单个肾单位 GFR(SNGFR) ;对老年大鼠 GFR和 SNGFR显著下降。血管紧张素在老年和年轻大鼠引起相同程度的入球和出球动脉阻力 (RA、RS)和 PGC升高。 Ang- 对老年大鼠和年轻大鼠近端小管绝对重吸收和相对重吸收均无影响。结论 在老年和年轻大鼠 ,入球和出球小动脉对升压剂量的血管紧张素有相同的敏感性 ,Ang- 对近端小管绝对重吸收和相对重吸收的作用不受年龄影响。但是 ,在老年大鼠 Kf对血管紧张素更敏感而导致 SNGFR的显著下降
Objective To investigate the effects of exogenous angiotensin (Ang-1) on the glomerular and renal tubules in the aged rats (19 ~ 22 months). Methods Using live micro-puncture technique. Results In the basal state, the aged rats had higher glomerular blood pressure (PGC) than the young rats (4-5 months old). In the injection of exogenous Ang-, both aged rats and young rats showed significant elevated blood pressure and renal vasoconstriction. In young rats, glomerular filtration rate (GFR) and single nephron GFR (SNGFR) were not altered; GFR and SNGFR were significantly decreased in aged rats. Angiotensin causes similar goals and increased resistance (RA, RS) and PGC in the aged and young rats. Ang-2 had no effect on absolute reabsorption and relative reabsorption of proximal tubules in aged rats and young rats. Conclusions In aged and young rats, both the goal and the arteriolar arterioles have the same sensitivity to the booster dose of angiotensin, and the effect of Ang- on proximal tubule absolute and relative reabsorption is independent of age. However, Kf is more sensitive to angiotensin in aged rats resulting in a significant decrease in SNGFR