Pre- and postflight 24-hour urine samples were collected from each crewman on the same days as the blood samples. Additionally, urine samples were collected in flight during the Apollo 16 and 17 missions only. Samples were collected using the Biomedical Urine Sampling System (BUSS), which contained a large 4-liter pooling bag in which the urine was collected. Each pooling bag also contained 10 g of boric acid for stabilizing certain organic constituents. The pooled urine was collected without additive, aliquoted, stabilized with boric acid, and frozen for analysis. One entire 24-hour urine sample was returned for each Apollo 16 crewman. For Apollo 17 collections, a sampling bag was used which could store as much as 120 cc of urine for later analysis. The Apollo 17 collection bags contained 30 ml of lithium chloride. The final lithium concentration was used to estimate total urine volume.
Blood samples were analyzed for osmolality, sodium, potassium, chloride, adrenocorticotropic hormone (ACTH), angiotensin I, cortisol, growth hormone (GH), insulin, parathormone, thyroxine, and tri-iodothyronine. The 24-hour urine samples were analyzed for electrolytes, osmolality, volume, aldosterone, cortisol, antidiuretic hormone (ADH), total and fractionated ketosteroids, and amino acids. Prolonged exposure to increased temperature and to the boric acid preservative made the urine samples collected inflight unsuitable for catecholamine or ADH analysis.
Apollo crewmen showed an average of 5% decrease in body weight after flight when the mean of the preflight results was compared to the individual postflight values. One-third of this weight was regained within 24 hours after recovery. Significant differences were observed in a 7.3 % decrease in potassium and a 4.5% decrease in magnesium immediately postflight. No significant changes in serum sodium or chloride accompanied these changes.
The 24-hour urine electrolyte results exhibited significant decreases in sodium, potassium, chloride and magnesium values. Renin activity, measured as angiotensin I in blood samples, and aldosterone levels, measured in urine, were aids in the understanding of water and electrolyte balance and renal function. Plasma angiotensin I values showed a 488 % increase in the crewmen tested on the day of recovery. This elevation was followed by a significant increase (57%) in urinary aldosterone during the first day following recovery. A postflight 32% decrease in urine volume was detected along with significant increases in osmolality (20%) and ADH (152%).
The creatinine clearance results showed no significant change in renal function after flight. A slight but significant increase in blood urea nitrogen (BUN) was found. Urinary calcium, phosphorus, and parathormone (PTH) results reflect normal bone metabolism and seem to reflect normal renal function, as well. Plasma cortisol and ACTH results showed no significant changes, but a mean decrease was found for each hormone. Urinary cortisol demonstrated a 24% increase, whereas the total 17-hydroxycorticosteriod excretion was decreased by 30%. Both catecholamine compounds showed decreases after flight when the data from all crewmen were grouped for analysis. Results of total and fractionated ketosteroid demonstrated a 30% decrease in the total component, which is spread over four fractions: androsterone, etiocholanolone, dehydroepiandrosterone (DHEA), and 11=OH etiocholanolone. A slight increase was observed in pregnanediol and 11=O etiocholanolone.
Glucose showed a 10% increase after flight and insulin showed an increase of 32% after flight. Human growth hormone demonstrated a 304% increase after flight. The postflight increase in thyroxine was statistically significant, whereas slight change was noted in percentage of tri-iodothyronine binding. Variable results were obtained when pre- and postflight levels of six urinary acids were compared. These amino acids were phosphoethanolamine, taurine, glycine, alanine, tyrosine, and ß-alanine. Taurine, however, was consistently elevated after flight by 140%.
After considering all of the previously mentioned data, together with the clinical condition of the returning Apollo crewmen, the following hypothesis was proposed to explain the changes: in a weightless environment, there is a tendency for plasma volume to shift from occupying the gravity-dependent extremities to occupying a more even distribution throughout the vascular system. Receptors, possibly in the right atrium, interpret this shift as an increase in vascular volume. This increased 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.
The crewmembers' in-flight diet of low-residue, high-fat and high-carbohydrate foods may have been the cause of decreased levels of cholesterol, triglycerides and uric acid. However, these values did not return to preflight levels in two weeks after the mission, even though the crew began eating a conventional diet immediately after recovery. This fact suggested possibly that other metabolic consequences were involved. Adrenal steroids have been shown to be elevated during flight which may have accounted for the decrease in the stores of precursor cholesterol, particularly if not replaced by the diet. The decreased cholesterol was in agreement with elevated thyroxine levels, and contributed to the evidence of increased thyroid function during flight.
|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|