Corticosteroid-induced stimulation of atrial natriuretic peptide in man

Previously, we reported elevated plasma immunoreactive ANP (irANP) levels from the 2nd to the 9th day of administering either prednisone, 50 mg/day, or 9 alpha-fludrocortisone acetate (9 alpha F), 0.6 mg/day, to normal humans. To investigate the course of plasma irANP levels during the first 48 h of corticosteroid administration, 9 healthy men (mean age +/- SEM, 24 +/- 1 years) received in randomised sequence A) a 4-h iv infusion of prednisolone sodium tetrahydrophthalate followed by oral administration of prednisone for 2 days; or B) a 4-h infusion of aldosterone followed by oral administration of 9 alpha F for 2 days. Basal supine plasma irANP levels averaged 32 +/- 5 ng/l in study A and 30 +/- 6 ng/l in study B; they were unchanged or even deceased up to 24 h of glucocorticoid or mineralocorticoid administration, but rose (P less than 0.01) to 56 +/- 9 and 62 +/- 12 ng/l at 48 h, respectively, of the two interventions. During glucocorticoid treatment, blood pressure (BP) and indices of the sodium-fluid volume state were unchanged after 48 h. During 9 alpha F administration, body weight increased (1.1 +/- 0.3%, P less than 0.001), whereas urinary sodium excretion (63 +/- 7%, P less than 0.001), hematocrit (4.1 +/- 1.1%, P less than 0.001), and plasma renin activity (38 +/- 4%, P less than 0.001) decreased. Conclusions: The increase in circulating irANP at 48 h of administration of either a glucocorticoid or a mineralocorticoid demonstrates a distinct but slow response of the ANP system to these corticosteroids in normal humans.(ABSTRACT TRUNCATED AT 250 WORDS)