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Metabolic changes observed in astronauts
C S Leach1, N M Cintrón, J M Krauhs
1Biomedical Operations and Research Branch, National Aeronautics and Space Administration, Johnson Space Center, Houston, Texas 77058.
Journal of Clinical Pharmacology
|October 1, 1991
Summary
Astronauts experience fluid shifts and dehydration during space flight, impacting physiological regulation. The body adapts to weightlessness, but this adaptation comes at a physiological cost.
Area of Science:
- Space medicine
- Human physiology
- Metabolic alterations
Background:
- Understanding physiological regulation is crucial for space exploration.
- Space flight induces significant metabolic and fluid shifts in astronauts.
Purpose of the Study:
- To investigate metabolic alterations during space flight.
- To understand the physiological regulatory mechanisms affected by space travel.
Main Methods:
- Analysis of medical experiment results from astronauts.
- Monitoring fluid volume, body water, and electrolyte levels.
- Assessing hormonal changes (renin, ADH, cortisol, thyroxine, insulin).
Main Results:
- Rapid fluid loss (2 L) from legs and headward fluid redistribution.
- 2-3% decrease in total body water within 2 days.
- Increased plasma renin activity and antidiuretic hormone; decreased blood sodium and plasma volume.
- Estimated 0.3 kg protein loss with endocrine changes favoring protein catabolism.
Conclusions:
- Space flight causes significant fluid and electrolyte loss.
- Endocrine factors during space flight promote protein catabolism.
- The human body adapts to weightlessness with physiological costs, posing challenges for re-adaptation to Earth's gravity.
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