Discrepancy Between Plasma and Lung Angiotensin-Converting Enzyme Activity in Experimental Congestive Heart Failure A Novel Aspect of Endothelium Dysfunction

The renin-angiotensin and cardiac natriuretic systems play an important role in the pathophysiology of congestive heart failure (CHF). The status of the membrane-bound pulmonary and renal activities of three ectoenzymes involved in the regulation of these systems — angiotensin-converting enzyme (ACE), neutral endopeptidase (NEP), and aminopeptidase A (APA) —was investigated in Wistar rats 3 months after induction of myocardial infarction (MI) and in sham-operated (control) rats. Plasma renin activity and ACE activity, plasma angiotensin II (Ang II) levels, and atrial natriuretic factor levels were simultaneously determined. The lung ACE activity was decreased in MI rats compared with control rats (P