Sawka M N, Gonzalez R R, Young A J, Muza S R, Pandolf K B, Latzka W A, Dennis R C, Valeri C R
US Army Research Institute of Environmental Medicine, Natick 01760-5007.
Am J Physiol. 1988 Sep;255(3 Pt 2):R456-63. doi: 10.1152/ajpregu.1988.255.3.R456.
We studied the effects of autologous erythrocyte infusion on thermoregulation and blood volume during exercise in the heat. Specifically, we wanted to determine whether heat-acclimated subjects, as well as hypohydrated subjects, would have a thermoregulatory advantage from acute polycythemia during exercise in the heat. Five heat-acclimated males attempted four heat stress tests (HSTs): two pre- and two postinfusion. Autologous erythrocyte infusion was accomplished with 500 ml of a NaCl-glucose-phosphate solution containing approximately 60% hematocrit. One HST, both pre- and postinfusion, was done while subjects were euhydrated, and one HST was done while subjects were hypohydrated (-5% of body wt). After 30 min of rest in a 20 degrees C antechamber, the HST consisted of a 120-min exposure (2 repeats of 15 min rest and 45 min walking) in a hot (35 degrees C, 45% relative humidity) environment. The findings concerning acute polycythemia in heat-acclimated subjects are summarized: 1) polycythemia increased (P less than 0.05) sweating rate and reduced (P less than 0.01) core temperature during exercise-heat stress for both euhydrated and hypohydrated subjects; 2) the erythrocyte infusion caused an increased (P less than 0.05) plasma volume and increased (P less than 0.01) blood volume; 3) the increased plasma volume was associated with an increased (P less than 0.05) total circulating protein mass; 4) the increased total circulating protein mass tended to better maintain plasma volume when hypohydrated; and 5) heat acclimation may increase extravascular protein mass. Therefore, it is concluded that erythrocyte infusion provides a thermoregulatory advantage during exercise in the heat for heat acclimated subjects when both euhydrated and hypohydrated.
我们研究了自体红细胞输注对热环境中运动期间体温调节和血容量的影响。具体而言，我们想确定热适应受试者以及轻度脱水受试者在热环境中运动时，急性红细胞增多症是否会带来体温调节优势。五名热适应男性进行了四项热应激测试（HST）：输注前两项，输注后两项。自体红细胞输注是通过500毫升含有约60%血细胞比容的氯化钠 - 葡萄糖 - 磷酸盐溶液完成的。一项输注前和输注后的HST是在受试者等渗状态下进行的，另一项HST则是在受试者轻度脱水（体重减轻5%）时进行的。在20摄氏度的前厅休息30分钟后，HST包括在炎热（35摄氏度，相对湿度45%）环境中进行120分钟的暴露（15分钟休息和45分钟步行重复两次）。关于热适应受试者急性红细胞增多症的研究结果总结如下：1）对于等渗和轻度脱水的受试者，红细胞增多症均增加了（P<0.05）出汗率并降低了（P<0.01）运动 - 热应激期间的核心体温；2）红细胞输注导致血浆量增加（P<0.05）和血容量增加（P<0.01）；3）血浆量增加与总循环蛋白质量增加（P<0.05）相关；4）总循环蛋白质量增加在轻度脱水时倾向于更好地维持血浆量；5）热适应可能增加血管外蛋白质量。因此，得出结论，对于热适应受试者，无论是等渗还是轻度脱水状态，红细胞输注在热环境中运动期间都提供了体温调节优势。
