Response of atrial natriuretic peptide in plasma and urine to changes in dietary intake of sodium chloride in man.

Plasma concentration and urinary excretion of immunoreactive human atrial natriuretic peptide (ir-hANP), aldosterone, and vasopressin were measured, and renal function and blood pressure were determined in six healthy male subjects in three periods of different sodium intake: the control (172 mEq/day), low (20 mEq/day), and high (285 mEq/day) sodium period. Both plasma concentration and urinary excretion of ir-hANP increased significantly in the high sodium period but did not change between the control and low sodium periods. On the contrary, aldosterone increased and vasopressin decreased in the low sodium period but did not change between the control and high sodium periods. These results may point out the reciprocal action of both endocrine systems. The glomerular filtration rate changed in parallel with sodium intake whereas the fractional excretion of sodium decreased only in the low sodium period, probably reflecting the action of aldosterone. It is concluded from these results that the atrial peptide may be an important component in the regulation of body fluid in the high sodium loading of physiological range but its action may be limited to the control of glomerular filtration rate.