PRINCIPAL INVESTIGATOR(S ): Carolyn S. Leach, W. Carter Alexander, and Philip 



C. Johnson 



EXPERIMENT TITLE/NUMBER : Endocrine, Electrolyte, and Fluid Volume Changes 



Associated with Apollo Missions 



PROGRAM/MISSION : Apollo 



CLASSIFICATION : Human 



DISCIPLINE(S) : Endocrinology, Environmental health 



OBJECTIVES : To evaluate the biochemical changes in Apollo crewmembers. The 

 areas studied were balance of fluids and electrolytes, regulation of calcium 

 metabolism, adaptation to the environment, and regulation of metabolic 

 processes . 



PROTOCOL : The same protocol was used for all the Apollo missions except 11, 

 12, and 14, which were in the lunar quarantine program. 45 ml of venous blood 

 was drawn 3 times before flight. 24 hour urine samples were collected pre- 

 and postf light at the same time. There was a ground control to determine 

 transport effects on the samples. Blood was analyzed for osmolality, Na, K, 

 CI, ACTH, angiotensin I, Cortisol, HGH, insulin, parathormone, thyroxine, and 

 triiodothyronine. Urine was analyzed for electrolytes, osmolality, volume, 

 aldosterone, Cortisol, ADH, ketosteroids, and amino acids. Radionuclide 

 studies were used. 



EQUIPMENT : Blood and urine collection devices, bioassay equipment. 



RESULTS : Total body water, and extra- and intracellular fluids decreased 2%. 

 Plasma volume was reduced 4%. There was a postf light decrease in urine 

 volume, and increase in osmolality. Na, K, CI, and Mg decreased. At R+0, 

 Cortisol, aldosterone, HGH, ADH, pregnanediol were elevated. Epinephrine, 

 17-hydroxycorticosteroids, androsterone, etiocholanolone decreased. At R+0, 

 the amino acids taurine, sarcosine, and B-alanine were elevated, whereas, 

 glycine, alamine, and tyrosine were reduced. 



CONCLUSIONS : The following hypothesis is presented to explain the mechanisms 

 underlying the observed electrolyte and fluid compartment changes: In a 

 weightless environment, there is a tendency for plasma volume to be 

 distributed more evenly within the vascular system and away from the gravity- 

 dependent extremities. This shift is interpreted by receptors, probably in 

 the right atrium, to be an increase in vascular volume. The increase in 

 vascular volume is counteracted by an increased water loss, followed by a 

 compensatory, adrenal-pituitary-mediated retention of water and sodium and by 

 a continued loss of potassium. Other hormone changes observed are tentatively 

 ascribed to the stresses associated with the condition of the Apollo space 

 flights, to the well known consequences of hypokinesis, and to the metabolic 

 effects of hypocaloric nutritional intake. 



PUBLICATIONS : 294, 295, 333, 341, 342, 343, 344, 348, 438, 474, 561 



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