AJP - Regulatory, Integrative and Comparative Physiology, Vol 251, Issue 3 450-R455, Copyright © 1986 by American Physiological Society
Renin-angiotensin system, converting-enzyme inhibition and kidney function in aging female rats
B. Corman and J. B. Michel
The age-related changes in the renin-angiotensin system were investigated
in normotensive 3-, 10-, 20-, and 30-mo-old female Wistar rats. Plasma
renin concentration and immunofluorescent renal renin index remained
constant from 3 to 10 mo, then decreased as the animals become older,
whereas plasma concentration of renin substrate diminished slightly between
10 and 20 mo and plasma converting-enzyme activity was not modified with
age. Acute inhibition of converting-enzyme activity by intravenous
administration of 0.1 mg/100 g body wt S 9780 (the diacid form of S 9490)
was followed by a 7- to 8-mmHg decrease in arterial pressure and a
concomitant 10-12% increase in inulin and p-aminohippuric acid (PAH)
clearance in the 10- and 20-mo-old rats. On the other hand, neither
glomerular filtration rate, PAH clearance nor arterial blood pressure were
affected by converting-enzyme inhibition in the 30 mo-old rats. These
results indicate that the activity of the renin-angiotensin system is
progressively reduced with age and suggest that angiotensin II does not
play an important role in the maintenance of blood pressure and kidney
hemodynamics in normotensive female senescent rats.
