Buono Michael J, Claros Ryan, Deboer Teshina, Wong Janine
San Diego State University, San Diego, CA 92182-7251, USA.
J Appl Physiol (1985). 2008 Oct;105(4):1044-8. doi: 10.1152/japplphysiol.90503.2008. Epub 2008 Jul 24.
The purpose of this study was to measure the in vivo Na(+) secretion and Na(+) reabsorption rates of the human eccrine sweat gland with increases in sweat rate. Such data should help to elucidate the physiological mechanism responsible for the previously reported linear relationship between increases in sweat rate and Na(+) concentration in sweat. On 5 days, each subject (n = 10) completed a 30-min exercise bout in an environmental chamber set at 35 degrees C and 40% relative humidity. The intensity for the five exercise bouts in the heat was set to approximate 50, 60, 70, 80, and 90% of age-predicted maximum heart rate. Forearm sweat samples and capillary blood samples were collected during each of the five 30-min exercise bouts. The sweat and blood samples were analyzed for Na(+) concentration in sweat and serum, which were used to calculate the rate of Na(+) secretion and Na(+) reabsorption. The mean correlation between sweat rate and Na(+) concentration in sweat was found to be r = 0.73. Within the sweat rate range of the present study, both Na(+) secretion rate and Na(+) reabsorption rate increased linearly; however, the Na(+) secretion rate increased almost twice as fast (slope = 141 vs. 80). Thus the rate at which Na(+) escaped reabsorption increased with increases in sweat rate and was significantly (P < 0.05) correlated to the Na(+) concentration in sweat (mean r = 0.90). Such results strongly suggest that the physiological mechanism responsible for the previously reported linear increase in Na(+) concentration in sweat seen with increases in sweat rate is that the Na(+) secretion rate increases proportionally more than the Na(+) reabsorption rate.
本研究的目的是测量随着出汗率增加，人外泌汗腺的体内钠（Na⁺）分泌率和钠（Na⁺）重吸收率。这些数据应有助于阐明导致先前报道的出汗率增加与汗液中钠（Na⁺）浓度之间线性关系的生理机制。在5天的时间里，每位受试者（n = 10）在温度设定为35摄氏度、相对湿度为40%的环境舱内完成了30分钟的运动。在炎热环境中进行的5次运动的强度设定为接近年龄预测最大心率的50%、60%、70%、80%和90%。在5次30分钟运动期间，每次都采集前臂汗液样本和毛细血管血样。对汗液和血样进行汗液和血清中钠（Na⁺）浓度分析，用于计算钠（Na⁺）分泌率和钠（Na⁺）重吸收率。发现出汗率与汗液中钠（Na⁺）浓度之间的平均相关性为r = 0.73。在本研究的出汗率范围内，钠（Na⁺）分泌率和钠（Na⁺）重吸收率均呈线性增加；然而，钠（Na⁺）分泌率增加的速度几乎快两倍（斜率分别为141和80）。因此，随着出汗率增加，钠（Na⁺）未被重吸收的速率增加，并且与汗液中钠（Na⁺）浓度显著相关（P < 0.05）（平均r = 0.90）。这些结果有力地表明，导致先前报道的随着出汗率增加汗液中钠（Na⁺）浓度呈线性增加的生理机制是钠（Na⁺）分泌率的增加比例大于钠（Na⁺）重吸收率。
