Shamsuddin A K M, Yanagimoto S, Kuwahara T, Zhang Y, Nomura C, Kondo N
Laboratory for Applied Human Physiology, Faculty of Human Development, Kobe University, 3-11Tsurukabuto, Nada-ku, Kobe 657-8501, Japan.
Eur J Appl Physiol. 2005 Jun;94(3):292-7. doi: 10.1007/s00421-005-1314-7. Epub 2005 Mar 12.
To investigate the pattern changes in the index of sweat ion concentration at skin surface with increasing sweat during passive heat stress in humans, we measured conductivity of the perfused water with sweat as the index of sweat ion concentration and sweat rate, continuously at the chest skin surface. Eight healthy subjects (22.4 +/-1.0 years) were passively heated by lower-leg immersion in a hot water bath of 42 degrees C for 50 min in an ambient temperature of 28 degrees C and relative humidity of 50%. The internal temperature (Tor) thresholds of sweat rate and index of sweat ion concentration were almost similar. Concomitant onset for the index of sweat ion concentration and sweat rate occurred but two types of linear regression lines were identified in the relationship between the index of sweat ion concentration and sweat rate at a boundary sweat rate value of 0.30 +/- 0.08 mg cm(-2) min(-1). The slope of the regression line at low levels of sweat (slope 0.02 +/- 0.01 V mg(-1) cm(-2) min(-1)) was significantly gradual compared with that at moderate levels of sweat (slope 0.30 +/- 0.08 V mg(-1) cm(-2) min(-1)) (P<0.05). These results suggest that at low levels of sweat the index of sweat ion concentration responds gradually with respect to sweat rate, which may be due to the ion reabsorption capacity of the sweat duct, and then the index of sweat ion concentration increased steeply with sweat rate.
为了研究人体在被动热应激期间随着出汗增加皮肤表面汗液离子浓度指标的变化模式，我们以汗液作为汗液离子浓度和出汗率的指标，连续测量胸部皮肤表面灌注水的电导率。八名健康受试者（22.4±1.0岁）在环境温度28℃、相对湿度50%的条件下，将小腿浸入42℃的热水浴中被动加热50分钟。出汗率和汗液离子浓度指标的内部温度（Tor）阈值几乎相似。汗液离子浓度指标和出汗率同时开始出现，但在出汗率边界值为0.30±0.08 mg cm(-2) min(-1)时，汗液离子浓度指标与出汗率之间的关系确定为两种类型的线性回归线。与中等出汗水平时的回归线斜率（斜率0.30±0.08 V mg(-1) cm(-2) min(-1)）相比，低出汗水平时回归线的斜率（斜率0.02±0.01 V mg(-1) cm(-2) min(-1)）明显更平缓（P<0.05）。这些结果表明，在低出汗水平时，汗液离子浓度指标对出汗率的反应较为平缓，这可能是由于汗腺导管的离子重吸收能力，然后汗液离子浓度指标随着出汗率急剧增加。
