Vital capacity, respiratory muscle strength, and pulmonary gas exchange during long-duration exposure to microgravity

被引:35
作者
Prisk, G. Kim [1 ]
Fine, Janelle M. [1 ]
Cooper, Trevor K. [1 ]
West, John B. [1 ]
机构
[1] Univ Calif San Diego, Div Physiol, Dept Med, La Jolla, CA 92093 USA
关键词
muscle atrophy; spaceflight; humans;
D O I
10.1152/japplphysiol.01419.2005
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
West. Vital capacity, respiratory muscle strength, and pulmonary gas exchange during long-duration exposure to microgravity. J Appl Physiol 101: 439-447, 2006. First published April 6, 2006; doi: 10.1152/japplphysiol. 01419.2005.-Extended exposure to microgravity (mu G) is known to reduce strength in weight-bearing muscles and was also reported to reduce respiratory muscle strength. Short-duration exposure to mu G reduces vital capacity (VC), a surrogate measure for respiratory muscle strength, for the first few days, with little change in O-2 uptake, ventilation, or end-tidal partial pressures. Accordingly we measured VC, maximum inspiratory and expiratory pressures, and indexes of pulmonary gas exchange in 10 normal subjects (9 men, 1 woman, 39-52 yr) who lived on the International Space Station for 130-196 days in a normoxic, normobaric atmosphere. Subjects were studied four times in the standing and supine postures preflight at sea level at 1 G, approximately monthly in mu G, and multiple times postflight. VC in mu G was essentially unchanged compared with preflight standing [5.28 +/- 0.08 liters (mean +/- SE), n = 187; 5.24 +/- 0.09, n = 117, respectively; P = 0.03] and considerably greater than that measured supine in 1G (4.96 +/- 0.10, n = 114, P < 0.001). There was a trend for VC to decrease after the first 2 mo of mu G, but there were no changes postflight. Maximum respiratory pressures in mu G were generally intermediate to those standing and supine in 1G, and importantly they showed no decrease with time spent in mu G. O-2 uptake and CO2 production were reduced (similar to 12%) in extended mu G, but inhomogeneity in the lung was not different compared with short-duration exposure to mu G. The results show that VC is essentially unchanged and respiratory muscle strength is maintained during extended exposure to mu G, and metabolic rate is reduced.
引用
收藏
页码:439 / 447
页数:9
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