THE ROLE OF ATRIAL-NATRIURETIC-PEPTIDE IN NATRIURESIS OF FASTING

Objective: To examine the relation between plasma atrial natriuretic peptide (ANP) and the natriuresis of fasting. Design: ANP, aldosterone and renin were examined during natriuresis of fasting in 25 obese essential hypertensive patients and nine overweight normotensive subjects placed on a supervised 500-KCal diet composed of 50% carbohydrates, 30% fat and 20% protein, and unlimited salt. Twenty-four-hour urinary electrolytes were measured on days 0, 4, 7 and 10 of the diet. Results: Urinary sodium concentration nearly doubled in the patients on day 4, and increased 1.4-fold in the normotensive controls. Plasma ANP rose nearly threefold in the hypertensives on day 4 and nearly doubled in the normotensives. Patients and controls showed similar patterns of natriuresis and ANP secretion during the diet. Conclusions: We conclude that there is a clear association between ANP levels and natriuresis of fasting.