Time-course and relationship of the early changes in renal sodium excretion and aldosterone secretion during dietary sodium restriction in normal man.
1. The fall in renal sodium excretion after dietary sodium restriction is prompt and reproducible. The importance of increased aldosterone secretion during the early phase (within 48 h) of this response is unclear. Using two indirect measures of aldosterone secretion (in urine and saliva), we have tried to relate changes in excretion and concentration of this hormone to renal sodium excretion during the abrupt transition from a normal (approximately 150 mmol/day) or high (260 mmol/day) to a low (5-25 mmol/day) sodium intake in 11 and seven male volunteers, respectively. 2. All subjects showed reduced renal sodium excretion within 36 h of dietary restriction, but the times at which increases in renal aldosterone excretion, saliva aldosterone concentration and plasma renin activity became statistically significant varied widely (8-72 h, 2.5- greater than 62.5 h and less than 4- greater than 38 h for renal aldosterone secretion, saliva aldosterone concentration and plasma renin activity, respectively). Circadian fluctuations in saliva aldosterone concentration were apparent and increased in amplitude during sodium restriction. 3. Urine flow rate tended to increase on the first day of sodium restriction and this reached statistical significance in the group initially on a high sodium intake (64.0 +/- 8.8 to 84.3 +/- 11.2 ml/h, P less than 0.01); although the pattern of urine flow did correlate with plasma arginine vasopressin concentration (r = -0.49, P less than 0.01), there was no significant decrease in mean plasma arginine vasopressin concentration [1.15 (0.92-1.44) to 0.90 (0.72-1.12) pmol/l, P = 0.08; geometric mean and 95% confidence limits].(ABSTRACT TRUNCATED AT 250 WORDS)
Carmichael
D J
DJ
Medical Unit, St Mary's Hospital Medical School, London.
Sutters
M S
MS
Unwin
R J
RJ
Gordon
D
D
Few
J
J
James
V H
VH
Wadsworth
J
J
Peart
W S
WS
D000328:Adult; D000450:Aldosterone / Q000378:metabolism*; D001127:Arginine Vasopressin / Q000097:blood; D009320:Atrial Natriuretic Factor / Q000097:blood; D004039:Diet, Sodium-Restricted; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D008297:Male; D012016:Reference Values; D012463:Saliva / Q000378:metabolism; D012964:Sodium / Q000652:urine*; D013997:Time Factors
D001127:Arginine Vasopressin; D000450:Aldosterone; D009320:Atrial Natriuretic Factor; D012964:Sodium