Greenleaf J E, Stinnett H O, Davis G L, Kollias J, Bernauer E M
J Appl Physiol Respir Environ Exerc Physiol. 1977 Jan;42(1):67-73. doi: 10.1152/jappl.1977.42.1.67.
Twelve women (23-34 yr), comprising a bed-rest (BR) group of eight subjects and an ambulatory (AMB) group of four subjects, were centrifuged after 14 days of ambulatory control (C),after 15 days of a 17-day BR period, and on the third day of recovery (R). Venous blood was taken before and after the third +3.0 G acceleration run (1.8 G/min). Relative to (C), the +Gz tolerance after BR was reduced -49.0% (P less than 0.05) in the BR group and -38.7% (NS) in the AMB group; during (R) the BR group regained up to 89.4% and the AMB group up to 87.1% of their (C) tolerances. In each of the three test periods, the shifts in plasma Na, Cl, PO4, and osmotic contents, which accompanied +Gz, followed the outward shift of plasma volume (PV). The correlation of the shift of PV during acceleration with the +Gz tolerance was 0.72 (P less than 0.01). During acceleration, the PV and electrolyte loss for both groups after BR was about half the loss of (C) and (R). Compared with (C) and (R) values, potassium shifts were variable but the mean corpuscular volume and mean corpuscular Hb contents and concentrations were unchanged during all +Gz runs; The results indicate that: 1) the higher the (C) + Gz tolerance, the greater the tolerance decline due to BR; 2) relative confinement and reduced activity contribute as much to the reduction in tolerance as does the horizontal body position during BR; 3) bed-rest deconditioning has no effect on the erythrocyte volume during +3.0 Gz; and 4) about one-half the loss in tolerance after BR can be attributed to PV and electrolyte shifts.
12名女性（年龄在23 - 34岁之间），包括一个有8名受试者的卧床休息（BR）组和一个有4名受试者的非卧床（AMB）组，在进行14天的非卧床对照（C）后、17天卧床休息期的第15天以及恢复（R）的第三天接受离心试验。在第三次+3.0G加速度运行（1.8G/分钟）前后采集静脉血。相对于（C），BR组在卧床休息后+Gz耐力降低了49.0%（P<0.05），AMB组降低了38.7%（无统计学意义）；在（R）期间，BR组恢复到其（C）耐力的89.4%，AMB组恢复到87.1%。在三个测试期的每一个中，伴随+Gz的血浆钠、氯、磷酸盐和渗透压含量的变化都跟随血浆容量（PV）的向外移动。加速过程中PV的变化与+Gz耐力的相关性为0.72（P<0.01）。在加速过程中，BR后两组的PV和电解质损失约为（C）和（R）损失的一半。与（C）和（R）值相比，钾的变化不定，但在所有+Gz运行期间平均红细胞体积、平均红细胞血红蛋白含量和浓度均无变化；结果表明：1）（C）+Gz耐力越高，因卧床休息导致的耐力下降越大；2）相对限制活动和活动减少对耐力降低的影响与卧床休息期间的水平身体姿势一样大；3）在+3.0Gz期间卧床休息导致的身体机能下降对红细胞体积没有影响；4）卧床休息后耐力损失的约一半可归因于PV和电解质的变化。
