Atrial natriuretic hormone and aldosterone regulation in salt-depleted state

To evaluate the effect of very low-dose infusion of atrial natriuretic hormone (ANH) on aldosterone regulation, seven normal young men were infused for 2.5 h with 0.47 pmol.kg-1.min-1 of human [Ser-Tyr28]ANH or placebo. During the last 0.5 h 4 pmol.kg-1.min-1 of angiotensin II were also infused. ANH plasma levels increased from 3.46 +/- 0.25 to a maximum of 6.80 +/- 0.88 pmol/l, which is well within normal limits. Plasma aldosterone decreased almost 40%, from 40.7 +/- 5.7 to 25.9 +/- 4.9 ng/dl after 2 h. ANH infusion caused a slight decrease in blood pressure and slight increase in renal excretion of sodium and potassium. These results suggest that even small changes in ANH levels, within the normal range, have physiological significance, particularly in aldosterone regulation.