Harrison M H, Edwards R J, Fennessy P A
J Appl Physiol Respir Environ Exerc Physiol. 1978 Jan;44(1):69-75. doi: 10.1152/jappl.1978.44.1.69.
The effect of alterations in intravascular volume and tonicity on thermoregulatory and cardiovascular responses to heat and exercise have been compared in four subjects. Core temperatures were found to be significantly higher during dehydration, and when dehydration was prevented by administration of 1% saline, than when dehydration was prevented by water administration. These higher temperatures were associated with elevated levels of plasma [Na] and osmolarity, but no consistent relationship between temperature and changes in intravascular volume could be demonstrated. Relationships observed between core temperature and plasma tonicity were consistent with the hypothesis that the adverse effects of dehydration on thermoregulation can be attributed to an inhibition of sweating mediated by an increase in either plasma osmotic pressure or plasma [Na]. In separate experiments the heart rate response to exercise was shown to be reduced by saline, compared with water and dehydration, and this may be explained by the smaller reduction in intravascular volume which occurs during exercise following administration of hypertonic saline. It is concluded that the effects of reduced intravascular volume, and increased intravascular tonicity on physical work capacity may be distinguished by the adverse effect on the cardiovascular system of the former, and on the thermoregulatory system of the latter.
在四名受试者中比较了血管内容量和张力的改变对热调节以及对热和运动的心血管反应的影响。发现脱水期间的核心温度显著高于通过给予1%盐水预防脱水时，也高于通过给予水预防脱水时。这些较高的温度与血浆[Na]水平和渗透压升高有关，但未发现温度与血管内容量变化之间存在一致关系。观察到的核心温度与血浆张力之间的关系与以下假设一致，即脱水对热调节的不利影响可归因于血浆渗透压或血浆[Na]升高介导的出汗抑制。在单独的实验中，与水和脱水相比，盐水显示出可降低运动时的心率反应，这可能是由于给予高渗盐水后运动期间血管内容量减少幅度较小所致。得出的结论是，血管内容量减少和血管内张力增加对体力工作能力的影响可能分别表现为前者对心血管系统的不利影响以及后者对热调节系统的不利影响。
