Allsopp A J, Sutherland R, Wood P, Wootton S A
Institute of Naval Medicine, Gosport, Hampshire, UK.
Eur J Appl Physiol Occup Physiol. 1998 Nov;78(6):516-21. doi: 10.1007/s004210050454.
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.
在热适应过程中，研究了控制钠摄入量对汗液钠分泌的影响。25名男性受试者先在25摄氏度的环境舱中停留3天，然后在40摄氏度下再进行5天的热适应。受试者的每日钠摄入量在整个过程中控制如下：高钠（HNa），348.4（0.8）mmol·天⁻¹，n = 7；中钠（MNa），174.1（0.6）mmol·天⁻¹，n = 9；或低钠（LNa），66.3 mmol·天⁻¹，n = 9。使用全身冲洗法从尿液、粪便和汗液收集量估算钠流失量。每天早晨还从静脉血中测量血浆醛固酮浓度。热暴露阶段的体温和心率测量表明有一定程度的热适应。在这个热阶段，所有三种情况下汗液钠分泌均减少（P < 0.01），其中LNa情况下降幅度最大，尽管这一发现无统计学意义（P < 0.1）。在LNa情况下，热暴露前血浆醛固酮浓度升高（P < 0.05），与MNa情况相比，热暴露期间醛固酮分泌增强（P < 0.01）。相反，HNa饮食在热暴露前使血浆醛固酮浓度下降（P < 0.05），此后醛固酮分泌减弱。这些发现与汗液钠潴留取决于机体净钠缺乏这一假设不一致，但表明在这种情况下醛固酮分泌增强。
