Cookies on this website
We use cookies to ensure that we give you the best experience on our website. If you click 'Continue' we'll assume that you are happy to receive all cookies and you won't see this message again. Click 'Find out more' for information on how to change your cookie settings.

Angiotensin converting enzyme (ACE, kininase II) is an endothelial luminal ectoenzyme expressed abundantly on the pulmonary capillary endothelium and recognized as the site for the conversion of circulating angiotensin I to II. In the present study, we have applied recently developed methodologies for assaying pulmonary capillary endothelium-bound (PCEB) ACE activity in man, to estimate the interaction of an ACE inhibitor (enalaprilat) with PCEB ACE in human subjects. Trace amounts of the specific ACE substrate, 3H-benzoyl-Phe-Ala-Pro (3H-BPAP; 40 Ci or 2 nmol), was injected as a bolus into the subclavian vein and immediately blood was withdrawn from a radial arterial catheter. Plasma concentrations of surviving substrate and product (3H-benzoyl-Phe) were estimated and BPAP utilization was calculated during a single transpulmonary passage, at baseline (T(0)) and at 15 min (T(15)) and 2 h (T(120)) after intravenous administration of 1.5 g/kg enalaprilat in 12 normotensive subjects. This treatment had no significant effect on mean arterial pressure (91+/- 6 vs. 84 +/- 7 vs. 88 +/- 6 mm Hg for T(0), T(15) and T(120), respectively), but significantly decreased serum and PCEB ACE activities. When normalized to predrug (T(0)) activity levels, enalaprilat inhibited PCEB and serum ACE activities at T(15) 74 +/- 6% and 68 +/- 6%, respectively. However, 2 h after enalaprilat (T(120)), PCEB ACE inhibition was maintained at 66 +/- 7%, whereas serum ACE inhibition was reduced to 46 +/- 8% (P<.01 from PCEB ACE), suggesting a preferential PCEB ACE inhibitory effect of enalaprilat.

Type

Journal article

Journal

Gen Pharmacol

Publication Date

10/2000

Volume

35

Pages

213 - 218

Keywords

Angiotensin-Converting Enzyme Inhibitors, Enalaprilat, Endothelium, Vascular, Humans, Lung, Peptidyl-Dipeptidase A