Life Sciences in the Space Program 



anticholinergic drugs (scopolamine) and amphetamine (11). Unfortunately, these 

 drugs may be associated with a decrease in crew performance, and their 

 effectiveness is unpredictable. Certainly, an understanding of the mechanism by 

 which vestibular function changes in space will result in a more effective approach 

 to the prevention and treatment of space motion sickness. 



The scientific questions are clearly multidisciplinary It is important to integrate the 

 various research activities accordingly. For example, do the neurophysiologists 

 investigating vestibular function consider that such changes may be brought about 

 by the hemodynamic changes of microgravity being investigated by the 

 cardiovascular physiologists? 



This question and others have broad relevance outside the operational responsi- 

 bilities of biomedical research at NASA. For example, does deterioration in 

 vestibular function result from the hemodynamic changes associated with 

 microgravity? Are these effects similar to those seen in Meniere's disease? The 

 answers to these scientific inquiries and the solutions to these clinical problems 

 may be found more expeditiously by close association between NASA and the 

 biomedical research community external to NASA. 



In short, the following questions in neurophysiology must be addressed: What are 

 the mechanisms responsible for the changes in neural function that occur in 

 microgravity? Do these changes in neural input contribute to the frequent reports 

 of space motion sickness? Are microgravity-induced changes in neural function 

 dependent upon the duration of microgravity, and what countermeasures will be 

 successful to treat changes in sensory perception, postural control mechanisms, 

 and neuroendocrine responses that occur in microgravity? 



The effects of the isolation and microgravity incurred by long-duration space flight 

 on interpersonal relationships, cognitive function, affect, and sexual function also 

 need to be investigated. Previous studies (12) have been too brief to allow 

 extrapolation for missions to Mars or the establishment of lunar bases. 



Endocrine and Musculoskeletal Physiology 



It has been reported that total body calcium losses average 0.3 percent per month 

 during space flight, and it is believed that most of the calcium loss comes from 

 weight-bearing boor (l.^). The loss ot body stores o! calcium may be due to 

 decreased oral intake of calcium in space flight, decreased absorption ot dietary 

 calcium, increased calcium resorption from bone in microgravity, and increased 

 urinary calcium loss. Serum calcium concentration is increased by parathyroid 

 hormone, which also promotes urinary phosphate kiss; ionized calcium 

 concentration is decreased in response to calcitonin. Calcium levels are also 

 affected by vitamin D and metabolites of vitamin D in the liver and kidneys. How 

 the action ol the hormones is affected by microgravity is not known. 



The mechanism by which there is a net negative balance ot calcium in micro- 

 ity is unknown. The low bone mass th.it results from increased calcium 



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