Costill D L, Coté R, Fink W
J Appl Physiol. 1976 Jan;40(1):6-11. doi: 10.1152/jappl.1976.40.1.6.
In an effort to assess the effects of dehydration on the content of water and electrolytes (Na+, K+, Cl-, and Mg2+) in plasma and muscle tissue, eight men exercised in the heat (39.5 degrees C, 25%). Blood urine, and muscle biopsy samples were obtained before exercise and after the subjects had reduced their body weight by 2.2, 4.1, and 5.8%. On the average, plasma and muscle water (H2Om) contents were found to decline 2.4 and 1.2% for each percent decrease in body weight. Muscle sodium (Na+m) and chloride (Cl-m) content remained unchanged with dehydration, while muscle magnesium (Mg2+m) declined 12% as a result of the 5.8% dehydration. In terms of intracellular concentrations, K+i increased 7.2 and 10.6% at the 2.2 and 4.1% dehydration levels, respectively. Calculations of the resting membrane potential suggest that the water and electrolyte losses observed in these studies do not significantly alter the excitability of the muscle cell membrane.
为了评估脱水对血浆和肌肉组织中水和电解质（Na+、K+、Cl-和Mg2+）含量的影响，八名男性在高温环境（39.5摄氏度，湿度25%）下进行运动。在运动前以及受试者体重下降2.2%、4.1%和5.8%后采集血样、尿样和肌肉活检样本。平均而言，体重每下降1%，血浆和肌肉中的水（H2Om）含量分别下降2.4%和1.2%。脱水时肌肉中的钠（Na+m）和氯（Cl-m）含量保持不变，而由于5.8%的脱水，肌肉中的镁（Mg2+m）下降了12%。就细胞内浓度而言，在2.2%和4.1%的脱水水平下，K+i分别增加了7.2%和10.6%。静息膜电位的计算表明，这些研究中观察到的水和电解质损失并未显著改变肌肉细胞膜的兴奋性。
