Plasma atrial natriuretic peptide, aldosterone, and plasma renin activity responses to gradual changes in dietary sodium intake

The present study examines the responses of plasma atrial natriuretic peptide (ANP), aldosterone and plasma renin activity to small alterations in dietary sodium intake. Six normotensive subjects were equilibrated on a low sodium intake of 10 mmol/day for 4 days. Dietary sodium intake was then increased gradually by 50 mmol/day to a maximum of 350 mmol/day over a 7 day period. With the gradual increase in sodium intake there were progressive increases in urinary sodium and cumulative sodium balance. These were associated with gradual increases in plasma ANP and reductions in both plasma aldosterone and plasma renin activity. During the study there were no significant changes in blood pressure, urinary potassium and creatinine clearance. This study demonstrates a marked sensitivity of the responses of both the ANP and the renin-aldosterone system to small changes in sodium intake and points to their importance in the renal adaptations to small alterations in dietary sodium intake.