Objective: The aims were (1) to quantitate angiotensin I to II conversion on the endothelial surface and at deeper sites in isolated arteries, (2) to assess whether the angiotensin II that is formed at deeper sites is released into the vascular lumen, and (3) to examine whether enzymes other than angiotensin converting enzyme (ACE) are involved in vascular angiotensin I to II conversion. Methods: Metabolism of [""I]-angiotensin I was studied in isolated perfused porcine coronary and carotid arteries after luminal administration of the labelled peptide (in the perfusion fluid) and after adventitial administration (in the organ bath). Measurements were made both in the presence and in the absence of captopril. Results: ['*'I]-angiotensin II was a major metabolite and its formation was virtually completely blocked by captopril, after both luminal and adventitial administration of ['251]-angiotensin I. In coronary arteries (n = S), the ['251]-angiotensin I to II conversion rate after adventitial administration was about half that after luminal administration. In coronary arteries (n = 6) the conversion rate after adventitial administration was lo-20 times lower than after luminal administration. Degradation of
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.