PRINCIPAL INVESTIGATQR(S ): G. Donald Whedon, Leo Lutwak, William F. Neuman, 



and Paul A. LaChanee 



EXPERIMENT TITLE/NUMBER : Calcium and Nitrogen Balance, M007 



PROGRAM/MISSION : Gemini 7 



CLASSIFICATION : Human 



DISCIPLINE(S) : Musculoskeletal 



OBJECTIVES : To collect data on the effects of a 1 4-day space flight on two of 

 the largest metabolically active tissue masses of the human body, the bones 

 and the muscles. 



PROTOCOL : By use of the metabolic-balance method, which involved precise 

 control of dietary intake and collection and analysis of all excreta, it was 

 possible to obtain a quantitative determination of the extent of change in the 

 principal inorganic constituents of the skeletal and muscular systems. The 

 extent of loss of inorganic constituents generally was proportional to the 

 extent of functional deterioration. Complete metabolic balance studies were 

 made measuring intake and excretion of calcium, magnesium, phosphate, 

 sulphate, nitrogen, sodium, potassium and chloride. 



EQUIPMENT : Urine collection device. 



RESULTS : Urinary phosphate excretion increased substantially inflight despite 

 a reduction of phosphate intake. Urinary nitrogen and sulfate excretion de- 

 creased inflight but to a lesser extent than would be expected from the 

 reduction in intake. Patterns of excretion of magnesium, sodium, potassium, 

 and chloride were different for each subject, and in part, could be correlated 

 with changes in adrenocortical steroid production. The principal hormonal 

 change was a striking decrease during flight in the urinary excretion of 17- 

 hydroxycorticosteroids . Dermal losses of calcium, magnesium, sulfate, 

 nitrogen, and phosphate were insignificant during all three phases. 



CONCLUSIONS : The changes in calcium metabolism and in other factors were 

 moderate enough to support (from the metabolic viewpoint) the decision that a 

 voyage to and from the Moon would be safe medically, because the time involved 

 would be no more (in fact, less) than was involved on the Gemini VII mission. 

 However, for assessment of the physiological safety and performance of 

 astronauts on future, much longer flights, the necessity is evident for 

 additional inflight metabolic observations. These observations must be 

 planned with better control, despite operational constraints. Such studies 

 will result in more reliable information for accurate prediction of the extent 

 of mineral and other metabolic changes to be expected in long-duration space 

 flight and will result in the establishment of a basis for judgment of the 

 necessity for development and assessment of corrective or protective measures. 



PUBLICATIONS : 358, 359, 360, 361, 362, 560, 561, 562, 563, 564, 565 



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