title: Aldosterone, atrial natriuretic factor and sodium intake as determinants of the natriuretic response to head-out water immersion in healthy subjects.
abstract: 1. The effect of sodium intake on the natriuresis and hormonal changes induced by head-out water immersion was studied in seven normal subjects during head-out water immersion and on a control day while successively on 20 mmol of sodium/day and 100 mmol of sodium/day diets. The effects of head-out water immersion were compared with those seen on the control day for both diets. 2. The natriuresis on the 100 mmol of sodium/day diet was significantly greater than on the 20 mmol of sodium/day diet (natriuretic peak: 10.3 +/- 2.2 versus 3.9 +/- 1 mmol of sodium/h; P less than 0.01). The total sodium excretion during the 3 h of head-out water immersion was 26.2 +/- 2.0 mmol on the 100 mmol of sodium/day diet and 9.9 +/- 0.9 mmol on the 20 mmol of sodium/day diet (P less than 0.01). In contrast, the increase in the plasma atrial natriuretic factor level was similar on both diets (peak plasma atrial natriuretic factor level 23.1 +/- 1.9 versus 26.2 +/- 1 pg/ml; not significant). As expected, the baseline serum aldosterone level was higher on the 20 mmol of sodium/day diet and, despite a significant suppression, remained significantly higher at the end of the third hour of head-out water immersion (peak serum aldosterone level: 495 +/- 130 versus 197 +/- 26 pmol/l, P less than 0.06). Furthermore, there was an inverse relationship between the serum aldosterone level and the urinary sodium excretion at the time of peak natriuresis (r = -0.59, P less than 0.01). 3. We conclude that the effect of sodium intake on the natriuresis induced by head-out water immersion is more dependent upon anti-natriuretic agents, such as aldosterone, than on natriuretic factors, such as atrial natriuretic factor.
authors.affiliation: Department of Medicine, University of Toronto, Canada.
authors.forename: L C
authors.initials: LC
authors.lastname: Warner
authors.forename: G A
authors.initials: GA
authors.lastname: Morali
authors.forename: J A
authors.initials: JA
authors.lastname: Miller
authors.forename: A G
authors.initials: AG
authors.lastname: Logan
authors.forename: K L
authors.initials: KL
authors.lastname: Skorecki
authors.forename: L M
authors.initials: LM
authors.lastname: Blendis
mesh_terms: D000328:Adult; D000450:Aldosterone / Q000097:blood*; D009320:Atrial Natriuretic Factor / Q000097:blood*; D006801:Humans; D007101:Immersion / Q000503:physiopathology*; D008297:Male; D009318:Natriuresis / Q000502:physiology*; D012982:Sodium, Dietary / Q000008:administration & dosage*
chemical_list: D012982:Sodium, Dietary; D000450:Aldosterone; D009320:Atrial Natriuretic Factor