Atrial natriuretic factor (ANF) has an inhibitory effect on angiotensin II and ACTH stimulated aldosterone secretion in man. The selectivity of this aldosterone suppressing effect of ANF is unclear in man. The present study investigated the effect of ANF on the increase in plasma aldosterone due to metoclopramide in man. 2. Eight normal male volunteers were studied on three occasions. Metoclopramide (10 mg slow i.v.) was given on all study days and each volunteer was randomised to receive 45 min infusion of either 5% D-glucose (placebo) or ANF (99-126) 3 or 15 pmol kg-1 min-1. 3. Metoclopramide increased plasma aldosterone to approximately 170% of baseline levels (P less than 0.01). Concomitant infusion of ANF 3 pmol kg-1 min-1 and 15 pmol kg-1 min-1 significantly attenuated this rise in plasma aldosterone to approximately 130% (P less than 0.05) and 110% (P less than 0.01) of baseline values respectively. 4. It is suggested, in the light of previous findings, that the inhibitory effect of ANF represents a non-selective action of ANF on aldosterone release.
