Stimulation and suppression of aldosterone in plasma of normal man and in primary aldosteronism

The effect of stimulating and suppressive influences on plasma aldosterone in normal man and in patients with primary aldosteronism were studied using a sensitive double-isotope derivative assay for aldosterone. In normal sitting subjects, values were 9.2+/-0.9 (SE) mmug/100 ml and in subjects supine for 1 hr plasma aldosterone was 5.2+/-0.4 (SE) mmug/100 ml. Adrenocorticotropic hormone (ACTH), 0.5 U/hr, produced a rise of 46.8+/-22 (SE) mmug which was similar to the 1-hr effect of an infusion of a synthetic ACTH (beta(1-24), Cortrosyn). Angiotensin II in pressor amounts also increased plasma aldosterone 21.5+/-2.9 (SE) without change in plasma cortisol, whereas a subpressor dose (unk) had minimal effect.Fludrocortisone, 1.2 mg/day for 3 days, suppressed plasma aldosterone levels to 1.8+/-0.7 (SE) mmug/100 ml in five normal sitting subjects (P < 0.01); however, dexamethasone, 2 mg/day for 1-2 days, did not lower aldosterone concentration in plasma. In six patients with primary aldosteronism, plasma aldosterone on a normal sodium diet was 39.1+/-4.4 (SE) which differed significantly from normal sitting or supine subjects (P < 0.001). In contrast to the normal subjects, neither a pressor infusion of angiotensin II for 1 hr, nor fludrocortisone, 1.2 mg/day for 3 days, impressively altered plasma aldosterone levels. This approach appears to be useful for the study of the acute physiology and control mechanisms of aldosterone production in normal and hypertensive man.