The objectives of the biochemical studies were:
1. To provide routine laboratory data for assessment of preflight crew physical status and for postflight comparisons.
2. To detect clinical or pathological abnormalities, which might have required remedial action preflight.
3. To discover, as early as possible, any infectious disease process during the postflight quarantine periods following certain missions.
4. To obtain fundamental medical knowledge relative to man's adjustment to and return from the space flight environment.
The medical history of each crewmember was obtained in order to evaluate the data obtained for this study. Medication history was obtained one month preflight, during flight, and postflight. Exposure to radiation and toxic products (if known) were recorded. Description of pertinent history and physical examination findings were also noted. The crew consumed a conventional diet during preflight and postflight periods and flight food throughout the mission. The approximate dietary intake as well as the amount and times of alcohol consumption were recorded. No restrictions were placed on fluid intake.
Biochemical measurements from all the Apollo crewmembers showed no values outside of the normal range established for the astronaut population. However, postflight results showed significant changes over preflight measurements. This comparison described consistent and significant decreases in potassium, magnesium, lactic dehydrogenase (LDH), creatine phosphokinase (CPK), albumin, uric acid, triglycerides and cholesterol. Increases were described in creatinine, total protein, blood urea nitrogen (BUN), and glucose.
Decreases were measured in the 24-hour urine volume and in the 24-hour excretion of sodium, potassium, chloride, magnesium, and uric acid. Increases were noted in specific gravity and osmolality. Since the preflight diet of the astronauts was not controlled, there was a large deviation in the means that resulted in large standard deviations.
Blood Constituents Measurements
Postflight decreases in serum potassium, although not significant clinically, were found in 24 of the 33 crewmembers. Based on samples collected during the Apollo 16 and 17 missions, the increase in aldosterone, which occurred during flight, was believed to be partly responsible for the decrease in serum potassium and for the lack of change in serum sodium postflight. A decrease in serum magnesium was interpreted as evidence of a reestablishment of ionic equilibrium, principally in muscle tissue, which occurred while in space.
Immediate preflight creatinine and blood urea nitrogen (BUN) levels were increased over preflight mean values with return toward preflight levels by one day after recovery. These increases, often associated with pre-renal diversion of water, increased protein catabolism and impaired renal function. Although no evidence of renal impairment was suggested in the chemistry data, it could not be ruled out. Increased protein catabolism or dietary factors probably influenced the creatinine and BUN levels, as well as the state of hydration of the returning crewmembers.
Serum Creatine Phosphokinase (CPK) levels was reduced immediately postflight, and mild elevations were evident 24 hours after recovery. This alteration was probably a result of both muscle inactivity incident to weightlessness and increased muscular activity during the first 24-hour postflight interval. The decrease in LDH could not be as readily explained, since this enzyme would be expected to increase with exercise. However, it is likely that preflight LDH levels were atypically elevated due to rigorous physical conditioning by the crew, such that the postflight level reduction in LDH may simply have been a return to normal enzyme balance.
Postflight levels of blood glucose were elevated indicating a possible reaction to the stress of reentry. This was supported by increases in epinephrine and steroid levels, which correlated well with the hematologic findings of leukocytosis. For additional results see experiment AP008 Endocrine, Electrolyte, and Fluid Volume Changes Associated with Apollo Missions. However, short-term bed rest is also associated with elevated glucose levels, and raised the possibility that these increased levels seen after the missions were not entirely a result of stress. This may have been a result of diminished uptake of glucose by inactive muscle cells. White blood cell counts reverted to preflight levels within 24 hours postflight.
The increase in total protein at recovery, and the subsequent decrease in the days following, portrayed the immediate postflight state of hydration of the individual crewmembers and the redistribution of fluid compartments that occurred throughout the postflight interval. The immunological proteins were elevated also in many of the crewmen, which perhaps contributed to total protein elevation.
Urine Constituent Measurements
Postflight 24-hour urine collections revealed significant retention of sodium, potassium, and chloride ions associated with reduced total urine volume and hyperosmolality. These findings are consistent with the reestablishment of preflight fluid and electrolyte balance and with hormonal adjustments required for readaptation for the space flight environment. The decrease in urinary uric acid predictably reflects the anabolism that occurs postflight. Although dietary factors cannot be ruled out in uric acid metabolism, by six days postflight the crewmember should have consumed diets sufficient to return those levels to the preflight mean.
|Mission||Launch/Start Date||Landing/End Date||Duration|
|Apollo 10||05/18/1969||05/26/1969||8 days|
|Apollo 11||07/16/1969||07/24/1969||8 days|
|Apollo 12||11/14/1969||11/24/1969||10 days|
|Apollo 13||04/11/1970||04/17/1970||6 days|
|Apollo 14||01/31/1971||02/09/1971||9 days|
|Apollo 15||07/26/1971||08/07/1971||12 days|
|Apollo 16||04/16/1972||04/27/1972||11 days|
|Apollo 17||12/07/1972||12/19/1972||12 days|
|Apollo 7||10/11/1968||10/22/1968||11 days|
|Apollo 8||12/21/1968||12/27/1968||6 days|
|Apollo 9||03/03/1969||03/13/1969||10 days|