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Alendronate and Resistive Exercise Countermeasures Against Bed Rest-Induced Bone Loss: Biochemical Markers of Bone and Calcium MetabolismWeightlessness-induced bone loss must be counteracted to ensure crew health during extendedduration space missions. Studies were conducted to assess two bone loss countermeasures in a ground-based model: horizontal bed rest. Following a 3-wk ambulatory adaptation period, male and female subjects (aged 21-56 y) completed a 17-wk bed rest protocol. Subjects were assigned to one of three treatments: alendronate (ALEN; 10 mg/d, n=6), resistive exercise (RE; 1.5 h/d, 6 d/wk, n=8), or control (CN; no countermeasure, n=8). Dietary intake was adjusted to maintain body weight. Endocrine and biochemical indices were measured in blood and urine using standard laboratory methods. All data reported are expressed as percent change from individual pre-bedrest data. Serum calcium changed little during bed rest, and tended to decrease (4-8%) in ALEN subjects. In RE subjects, bone alkaline phosphatase and osteocalcin were increased >65 and >30%, respectively, during bed rest, while these were unchanged or decreased in ALEN and CN subjects. Urinary calcium was increased 50% in CN subjects, but was unchanged or decreased in both ALEN and RE groups. Urinary n-telopeptide excretion was increased 40-50% in CN and RE subjects, but decreased 20% in ALEN subjects. Pyridinium crosslink and deoxypyridinoline excretion were increased 20-50% during bed rest. These data suggest that RE countermeasures are effective at increasing markers of bone formation in an analog of weightlessness, while ALEN reduces markers of bone resorption. Counteracting the bone loss of space flight may require both pharmacologic and exercise countermeasures.
Document ID
20100033618
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Smith, Scott M. (NASA Johnson Space Center Houston, TX, United States)
Nillen, Jeannie L. (Enterprise Advisory Services, Inc. Houston, TX, United States)
Davis-Street, Janis E. (Enterprise Advisory Services, Inc. Houston, TX, United States)
DeKerlegand, Diane E. (Enterprise Advisory Services, Inc. Houston, TX, United States)
LeBlanc, Adrian (Baylor Coll. of Medicine Houston, TX, United States)
Shackelford, Linda C. (NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 25, 2013
Publication Date
March 31, 2001
Subject Category
Aerospace Medicine
Report/Patent Number
JSC-CN-6480
Meeting Information
Meeting: Experimental Biology 2001
Location: Orlando, FL
Country: United States
Start Date: March 31, 2001
End Date: April 4, 2001
Distribution Limits
Public
Copyright
Public Use Permitted.

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