Effects of changes in dietary sodium intake and saline infusion on immunoreactive atrial natriuretic peptide in human plasma.

Plasma levels of immunoreactive atrial natriuretic peptide (IrANP) were measured in healthy normotensive subjects before and after saline infusion and changes in dietary salt intakes. When 2 litres of 0.9% saline (308 mmol Na+) were infused over 1 h, plasma levels (mean +/- SD) of IrANP increased from 5.8 +/- 2.8 pg/ml to 15.8 +/- 12.5 pg/ml. Plasma levels on the fifth day of a low sodium diet (10 mmol/day) were 3.8 +/- 2.4 pg/ml, a normal sodium intake (150 mmol/day) 6.4 +/- 2.9 pg/ml, and a high salt intake (350 mmol/day) 12.7 +/- 6 pg/ml. These results suggest that atrial natriuretic peptides could be important hormones in the control of sodium balance in normal man.