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Calcium and Bone Homeostasis During 4-6 Months Space FlightBone and calcium homeostasis are altered by weightlessness. We previously reported calcium studies on three subjects from the first joint US/Russian mission to Mir. We report here data on an additional three male subjects, whose stays on Mir were 4 (n= 1) and 6 (n=2) mos. Data were collected before, during, and after the missions. Inflight studies were conducted at 2-3 mos. Endocrine and biochemical indices were measured, along with 3-wk calcium tracer studies. Percent differences are reported compared to preflight. Ionized calcium was unchanged (2.8 +/-2.1 %) during flight. Calcium absorption was variable inflight, but was decreased after landing. Vitamin D stores were decreased 35 +/-24% inflight, similar to previous reports. Serum PTH was decreased 59 +/-9% during flight (greater than we previously reported), while 1,25(OH)(sub 2)-Vitamin D was decreased in 2 of 3 subjects. Markers of bone resorption (e.g., crosslinks) were increased in all subjects. Bone-specific alkaline phosphatase was decreased (n=1) or unchanged (n=2), while osteocalcin was decreased 34 +/-23%. Previously presented data showed that inflight bone loss is associated with increased resorption and unchanged/decreased formation. The data reported here support these earlier findings. These studies will help to extend our understanding of space flight-induced bone loss, and of bone loss associated with diseases such as osteoporosis or paralysis.
Document ID
20000089878
Document Type
Preprint (Draft being sent to journal)
Authors
Smith, Scott M. (NASA Johnson Space Center Houston, TX United States)
OBrien, K.
Wastney, M.
Morukov, B.
Larina, I.
Abrams, S.
Lane, H.
Nillen, J.
Davis-Street, J.
Paloski, W. H.
Date Acquired
August 19, 2013
Publication Date
January 1, 2000
Subject Category
Aerospace Medicine
Meeting Information
Experimental Biology(San Diego, CA)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.