Atrial natriuretic peptide and sodium intake: blunted effects in the normal sodium-retaining kidney

An intravenous bolus of 100 μg synthetic human atrial natriuretic peptide (ANP) produced a brisk rise in the excretion of sodium, chloride, calcium, magnesium, phosphorus and water in healthy subjects taking a 200 mmol/day sodium diet. After 4 days of a 20 mmol/day sodium diet, ANP produced qualitatively similar but markedly blunted effects. For example, net sodium loss in the 60 min following ANP was 17.7 ± 2.2 mmol during the 200 mmol sodium diet, versus only 4.8 ± 0.5 mmol during the low sodium diet (P < 0.01). Natriuresis after ANP involved a rise in glomendar filtration and in fractional sodium excretion. During the low sodium intake, the rise after ANP in fractional sodium excretion but not in glomerular filtration rate was blunted. Adaptation to changes in sodium intake apparently involves adjustment of the renal responsiveness to ANP, in particular its potential to reduce tubular sodium reabsorption. Neth J Med 1987;30:10-16. © 1987.