ARTICLE: PDF OnlyWelsch C.; Giesen-Crouse, E. M.; Schmidt, M.; Imbs, J. L.Journal of Cardiovascular Pharmacology: 1987 - p 129-132 Free Abstract Summary Angiotensin-converting enzyme (ACE) activity was measured in the plasma, the kidney, and other organs of 5-, 8-, and II-week-old spontaneously hypertensive male rats (SHR) of the Okamoto–Aoki strain and compared with that of age-matched Wistar–Kyoto (WKY, bred by Iffa-Credo) or normotensive Wistar rats. ACE activity was measured spectrofluorometrically, using the artificial substrate N–CBZ–L-phe–L-his–L-Ieu. ACE activity was constantly lower in the plasma and renal cortex of SHR from 5 weeks on than in WKY rats. This difference in the renal cortex ACE activity persisted after 1 h of open circuit perfusion of the isolated kidney with Krebs–Henseleit medium. On the other hand, there lung, the brain occipital cortex, or the abdominal aorta of hypertensive or normotensive rats. The percentage inhibition of ACE activity provoked by 7 days of oral administration of ramipril (Hoe 498, 1 mg/kg/day) was analogous in the kidneys and lungs of WKY rats and SHR. Enalapril (MK 421, 30 mg/kg/day) was equipotent to ramipril in the kidney but had lower inhibitory effects on the pulmonary ACE activities of WKY rats and SHR. Copyright © 1987 Wolters Kluwer Health, Inc. All rights reserved.