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The effect of sodium balance on sweat sodium secretion and plasma aldosterone concentration

The effect of sodium balance on sweat sodium secretion and plasma aldosterone concentration
The effect of sodium balance on sweat sodium secretion and plasma aldosterone concentration
The effect of manipulating sodium intake upon sweat sodium secretion was investigated during heat acclimation. Twenty-five male subjects were confined to an environmental chamber at a temperature of 25 degrees C for 3 days, and then acclimated to heat by a further 5 days at 40 degrees C. The subjects' daily sodium intake was controlled throughout as follows: high (HNa), 348.4 (0.8) mmol x day(-1), n=7; moderate (MNa), 174.1 (0.6) mmol x day(-1), n=9; or low (LNa), 66.3 mmol x day(-1), n=9. Sodium losses were estimated from urinary, faecal and sweat collections using a whole-body washdown method. Plasma aldosterone concentration was also measured from venous blood sampled each morning. Measurements of body temperature and heart rate during the heat exposure phase indicated a degree of heat acclimation. During this heat phase there was a reduction (P < 0.01) in sweat sodium secretion for all three conditions which was greatest for the LNa condition, although this finding was not significant (P < 0.1). In the LNa condition, plasma aldosterone concentration increased (P < 0.05) prior to heat exposure, and the secretion of aldosterone was potentiated (P < 0.01) during the heat exposure in comparison with the MNa condition. In contrast, the HNa diet produced a fall (P < 0.05) in plasma aldosterone concentration prior to heat exposure and an attenuation of aldosterone secretion thereafter. These findings are inconsistent with the hypothesis that retention of sweat sodium is dependent upon a net body sodium deficit, but demonstrate that aldosterone secretion is potentiated under such conditions.
0301-5548
516-21
Allsopp, A.J.
c4b438fa-7cac-4165-8cb8-004399b49ef4
Sutherland, R.
af9b1cda-b9cb-496f-b995-904967e9e28e
Wood, P.
24642270-7542-4923-ba8c-2780e8601d81
Wootton, S.A.
bf47ef35-0b33-4edb-a2b0-ceda5c475c0c
Allsopp, A.J.
c4b438fa-7cac-4165-8cb8-004399b49ef4
Sutherland, R.
af9b1cda-b9cb-496f-b995-904967e9e28e
Wood, P.
24642270-7542-4923-ba8c-2780e8601d81
Wootton, S.A.
bf47ef35-0b33-4edb-a2b0-ceda5c475c0c

Allsopp, A.J., Sutherland, R., Wood, P. and Wootton, S.A. (1998) The effect of sodium balance on sweat sodium secretion and plasma aldosterone concentration. European Journal of Applied Physiology and Occupational Physiology, 78 (6), 516-21. (PMID:9840406)

Record type: Article

Abstract

The effect of manipulating sodium intake upon sweat sodium secretion was investigated during heat acclimation. Twenty-five male subjects were confined to an environmental chamber at a temperature of 25 degrees C for 3 days, and then acclimated to heat by a further 5 days at 40 degrees C. The subjects' daily sodium intake was controlled throughout as follows: high (HNa), 348.4 (0.8) mmol x day(-1), n=7; moderate (MNa), 174.1 (0.6) mmol x day(-1), n=9; or low (LNa), 66.3 mmol x day(-1), n=9. Sodium losses were estimated from urinary, faecal and sweat collections using a whole-body washdown method. Plasma aldosterone concentration was also measured from venous blood sampled each morning. Measurements of body temperature and heart rate during the heat exposure phase indicated a degree of heat acclimation. During this heat phase there was a reduction (P < 0.01) in sweat sodium secretion for all three conditions which was greatest for the LNa condition, although this finding was not significant (P < 0.1). In the LNa condition, plasma aldosterone concentration increased (P < 0.05) prior to heat exposure, and the secretion of aldosterone was potentiated (P < 0.01) during the heat exposure in comparison with the MNa condition. In contrast, the HNa diet produced a fall (P < 0.05) in plasma aldosterone concentration prior to heat exposure and an attenuation of aldosterone secretion thereafter. These findings are inconsistent with the hypothesis that retention of sweat sodium is dependent upon a net body sodium deficit, but demonstrate that aldosterone secretion is potentiated under such conditions.

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Published date: November 1998
Organisations: Human Development & Health

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Local EPrints ID: 383843
URI: https://eprints.soton.ac.uk/id/eprint/383843
ISSN: 0301-5548
PURE UUID: 91bb4ae4-56aa-4653-b9ad-30f1e95c25e7

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Date deposited: 25 Nov 2015 11:21
Last modified: 17 Jul 2017 20:09

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Contributors

Author: A.J. Allsopp
Author: R. Sutherland
Author: P. Wood
Author: S.A. Wootton

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