摘要目的:探讨老年大鼠（19~22月龄）皮层肾小球毛细血管对外源性血管紧张素Ⅱ（ANGⅡ）的敏感性。方法:利用活体微穿刺技术。结果:在年轻大鼠，ANGⅡ导致肾血浆流量（RPF）和肾小球血浆流量（Q A）下降，伴随肾小球血压（P GC）和肾小球静水压梯度的升高，而肾小球毛细血管超滤系数（K f）基本不变，所以，不改变肾小球滤过率（GFR）和单个肾单位GFR（SNGFR）。在老年大鼠，RPF和Q A下降，P GC升高，K f显著下降，GFR和SNGFR显著下降。ANGⅡ在老年和年轻大鼠引起相同程度的入球和出球动脉阻力（R A，R E）和Pcc升高。 结论:老年和年轻大鼠的入球和出球小动脉对ANGⅡ有相同的敏感性，而老年大鼠K f对ANGⅡ更敏感而导致SNGFR的显著下降。

abstractsObjective:To investigate the sensitivity of the cortical glomerular microvasculature of the old rat kidney to exogenous angiotensin Ⅱ (ANG Ⅱ).Methods:Using the in vivo micropuncture technique in SD rats.Results:In the baseline state, glomerular blood pressure (P GC) in old male rats was higher compared to young rats. During exogenous ANG Ⅱ infusion, a significant rise in arterial pressure and renal vasoconstriction occurred in both old and young rats. In young rats, the ANG Ⅱ induced a fall in renal plasma flow (RPF) and glomerular plasma flow (Q A) was accompanied by a rise in P GC and thus the glomerular hydrostatic pressure gradient, with little change in glomerular capillary ultrafiltration coefficient (K f). Therefore, the glomerular filtration rate (GFR) and single nephron GFR (SNGFR) were unchanged. In old rats, RPF and Q A fell, a rise occurred in P GC and also a fall was seen in the K f thus GFR and SNGFR fell significantly. The magnitude of pressor and renal vasoconstriction response to ANG Ⅱ were not affected by age; ANG Ⅱ increased afferent and efferent arteriolar resistance (R A, R E) and P GC by similar amounts in young and old rats. Conclusion:The afferent and efferent arteriols had similar sensitivity to exogenous pressor dose of ANG Ⅱ in both young and old rats, but K f was more sensitive to ANG Ⅱ in old rats leading to significant fall in SNGFR.