Effect of varying potassium intake on atrial natriuretic hormone-induced suppression of aldosterone

To further assess the mechanism of atrial natriuretic hormone (ANH) induced suppression of aldosterone, we infused 0.5 pmol/kg/min Ser-Tyr28 human ANH over 2 h under three dietary conditions: low salt (LS), low potassium (LK), and high potassium (HK). The diets were consumed for 3 days before each study day. After 3 days of LK diet, blood pressure was slightly higher than under the other conditions. Serum potassium on LK was significantly lower than on HK (3.8 +/- 0.1 v 4.3 +/- 0.2). The ANH infusion did not cause any changes in blood pressure or urinary sodium and potassium excretion. Urine volume increased with ANH infusion under all diet conditions. Plasma renin activity and plasma angiotensin II levels were significantly lower on LK than on LS or HK, probably reflecting sodium retention. Increase in plasma ANH levels of about 75% (well within normal range) suppressed all hormonal parameters on LS and HK diets, but had no significant effect on LK diet. The pattern of aldosterone changes closely followed the changes in the renin-angiotensin system. We conclude that under various physiologic conditions ANH suppresses aldosterone predominantly through suppression of renin.