Angiotensin converting enzyme inhibition reduces ACTH release due to hypoglycaemia

To investigate the role of Angiotensin II in the release of ACTH, the response of adrenocorticotrophic hormone to hypoglycaemia was studied before and during treatment with an angiotensin converting enzyme inhibitor, enalapril, in 15 male patients with essential hypertension. Plasma levels of ACTH were measured before and 60, 90 and 120 min after an i.v. bolus of normal saline, as placebo, and, 3 days later, after an i.v. bolus of regular insulin (0.15 U/Kg b.w.). Enalapril treatment was then started and both placebo and hypoglycaemic tests were repeated 15 days thereafter. No changes in ACTH plasma levels were observed after acute normal saline either before or during enalapril treatment. On the contrary, hypoglycaemia induced a sharp increase of ACTH before enalapril (from 19.5 +/- 4.1 to 74.4 +/- 13.0 pg/ml, p less than 0.01 60 min after insulin) but not during ACE inhibition (from 26.1 +/- 6.2 to 34.6 +/- 5.9 pg/ml, NS, at min 60 of the study). The present data confirm our previous observation on the reduction of the hypoglycaemic-induced ACTH release during ACE inhibition with captopril and support the hypothesis that circulating Ang II may exert a facilitating role on adrenocorticotrophic hormone release.