Compensatory increase ln adrenomedullary angiotensin-converting enzyme activity (kininase II) after unilateral adrenalectomy

Abstract

Angiotensin-converting enryme (ACE, kininase II. dipeplidyl carboxypeptidase, EC 3.4.15.1) was characterized in the adrenal medulla of male Sprague-Dawley rats. Rat adrenal medulla and lung ACE we¡e similar in their susceptibility to Cl - activation and to the inhibition by EDTA, captopril, bacitracin and thiorphan, suggesting that rat adrenal medulla and lung ACE have similar properties. Changes in right adrenal weight and in adrenomedullary ACE activity 5 and l2 days following lcft unilateral adrenalectomy (UADX) were examined. Compensatory adrenocortical hypertrophy 12 days foliowing UADX was associated with a significant increase in adrenal medullary ACE activity. This change was due not to a modified affinity of ACE for the substrate but to an alteration in ACE maximal velocity or number of available molecules. UADX had no effect on adrenocortical ACE activity. When UADX was combincd with ight splanchnic denervation, the increase in adrenomedullary ACE activity was blocked. The results support the existence ol a lunctional ACE in adrenal medulla that is under neuronal control.