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Premium Changes in markers of bone formation and resorption in a bed rest model of weightlessness
Author(s)
Lueken Sandra A.,
Arnaud Sara B.,
Taylor Arch K.,
Baylink David J.
Publication year1993
Publication title
journal of bone and mineral research
Resource typeJournals
PublisherJohn Wiley and Sons and The American Society for Bone and Mineral Research (ASBMR)
Abstract To study the mechanism of bone loss in physical unloading, we examined indices of bone formation and bone resorption in the serum and urine of eight healthy men during a 7 day −6° head‐down tilt bed rest. Prompt increases in markers of resorption — pyridinoline (PD), deoxypyridinoline (DPD), and hydroxyproline (Hyp)/g creatinine—during the first few days of inactivity were paralleled by tartrate‐resistant acid phosphatase (TRAP) with significant increases in all these markers by day 4 of bed rest. An index of formation, skeletal alkaline phosphatase (SALP), did not change during bed rest and showed a moderate 15% increase 1 week after reambulation. In contrast to SALP, serum osteocalcin (OC) began increasing the day preceding the increase in Hyp, remained elevated for the duration of the bed rest, and returned to pre‐bed rest values within 5 days of reambulation. Similarly, DPD increased significantly at the onset of bed rest, remained elevated for the duration of bed rest, and returned to pre‐bed rest levels upon reambulation. On the other hand, the other three indices of resorption, Hyp, PD, and TRAP, remained elevated for 2 weeks after reambulation. The most sensitive indices of the levels of physical activity proved to be the noncollagenous protein, OC, and the collagen crosslinker, DPD. The bed rest values of both these markers were significantly elevated compared to both the pre‐bed rest values and the post‐bed rest values. The sequence of changes in the circulating markers of bone metabolism indicated that increases in serum OC are the earliest responses of bone to head‐down tilt bed rest.
Subject(s)alkaline phosphatase , bed rest , biochemistry , bone remodeling , bone resorption , chemistry , creatinine , deoxypyridinoline , endocrinology , enzyme , hydroxyproline , medicine , osteocalcin , pyridinoline , resorption , rest (music)
Language(s)English
SCImago Journal Rank1.882
H-Index241
eISSN1523-4681
pISSN0884-0431
DOI10.1002/jbmr.5650081204

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