Plasma levels of atrial natriuretic peptide (ANP) during mineralocorticoid escape in normal man.

A natriuretic factor has long been postulated to play a role in renal mineralocorticoid escape. We therefore investigated changes in plasma levels of atrial natriuretic peptide (ANP) during chronic treatment with 9 alpha-fluorohydrocortisone. Five normal subjects were studied on a constant diet (300 meq Na+ and 72 meq K+ per day) and received 0.8 mg 9 alpha-fluorohydrocortisone for up to 14 days. Sodium balance became positive and body weight increased between 1.0-4.5 kg maximally. Serum aldosterone was suppressed and plasma levels of ANP were stimulated up to 10-fold. Increment in plasma ANP was positively correlated with the gain in body weight (r = 0.666, p less than 0.001). Renormalization of sodium balance was seen in two subjects, however the maximum in plasma ANP did not occur during the time of renal escape. ANP-secretion is stimulated during sodium retention induced by mineralocorticoids, however ANP does not seem to trigger the escape mechanism.