The effect of human atrial natriuretic peptide on urinary sodium and urinary dopamine excretion in man.

Atrial extracts have long been known to produce natriuresis but it is only recently that atrial natriuretic peptide (ANP) itself has been isolated, purified and sequenced. We have now developed a specific radio-immunoassay for ANP and assessed its biological activity by infusing ANP in normal volunteers. Low dose ANP infusion (1.5 pmol/kg per min) produced no haemodynamic or natriuretic effects. High dose ANP infusion (15 pmol/kg per min) produced an increase in plasma immunoreactive ANP levels of 203 +/- 78 pmol/l and caused the urinary sodium excretion to increase from 3.5 +/- 1.6 to 11.0 +/- 7.4 mmol/30 min period (P < 0.05). No haemodynamic effects were seen with this high dose infusion. No changes in urinary dopamine were seen with either ANP infusion. This study shows that ANP is capable of producing a natriuresis in man in the absence of any generalized haemodynamic effects and that ANP may be an important modulator of salt and water balance in man.