PLASMA-IMMUNOREACTIVE ATRIAL-NATRIURETIC-PEPTIDE AND CHANGES IN DIETARY-SODIUM INTAKE IN MAN

Plasma levels of immunoreactive atrial natriuretic peptides (IrANP) have been measured in 8 normotensive subjects during alterations in dietary sodium intake. Subjects were studied on their normal sodium intake (2 days) then on a low sodium intake (7 days, 10 mmols Na+/day) and subsequently on a high sodium intake (14 days, 350 mmols Na+/day) with the diets being given in a fixed order. Plasma levels (mean .+-. S.E.M.) of IrANP on a normal sodium diet were 7.3 .+-. 0.9 pg/ml; 4.5 .+-. 0.8 on the 7th day of a low sodium intake and 10.8 .+-. 1.3; 16.6 .+-. 3.3; 15.5 .+-. 4.2; 15.6 .+-. 2.3 pg/ml respectively on the 1st, 3rd, 10th and 14th day on the high sodium intake. Changes in plasma IrANP were closely associated with changes in urinary sodium excretion. These results suggest that in normal subjects the atrial natriuretic peptides may play an important role in the adaptation to increases in dietary sodium intake both on a short and on a longer term basis.