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This Article Full Text Full Text (PDF) All Versions of this Article: 105/4/1255    most recent 00573.2007v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Martinez, D. A. Articles by Vailas, A. C. PubMed PubMed Citation Articles by Martinez, D. A. Articles by Vailas, A. C.

A noninvasive analysis of urinary musculoskeletal collagen metabolism markers from rhesus monkeys subject to chronic hypergravity

¹Connective Tissue Physiology Laboratory, Department of Health and Human Performance, ²Biomedical Engineering Program, Department of Mechanical Engineering, University of Houston, Houston, Texas; ³Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California; ⁴Center of Alcohol Studies, Rutgers, The State University of New Jersey, Piscataway, New Jersey; and ⁵Office of the President, Idaho State University, Pocatello, Idaho

Submitted 25 May 2007 ; accepted in final form 18 July 2008

A decrease in load-bearing activity, as experienced during spaceflight or immobilization, affects the musculoskeletal system in animals and humans, resulting in the loss of bone and connective tissue. It has been suggested that hypergravity (HG) can counteract the deleterious effects of microgravity-induced musculoskeletal resorption. However, little consensus information has been collected on the noninvasive measurement of collagen degradation products associated with enhanced load-bearing stress on the skeleton. The purpose of this study is to assess the urinary collagen metabolic profiles of rhesus monkeys (Macaca mulatta) during 1) 2 wk of basal 1 G (pre-HG), 2) 2 wk of HG (2 G), and 3) two periods of post-HG recovery (1 G). Urine was collected over a 24-h period from six individual rhesus monkeys. Hydroxyproline (Hyp) and collagen cross-links (hydroxylysylpyridinoline and lysylpyridinoline) were measured by reverse-phase HPLC. Urinary calcium, measured by atomic absorption, and creatinine were also assayed. The results indicate no changes in nonreducible cross-links and Hyp during HG. Collagen cross-link biomarker levels were significantly elevated during the 2nd wk of HG. Urinary calcium content was significantly lower during HG than during the 1-G control period, suggesting calcium retention by the body. We conclude that there is an adaptation of the nonhuman primate musculoskeletal system during hyperloading and that noninvasive measurements of musculoskeletal biomarkers can be used as indicators of collagen and mineral metabolism during HG and recovery in nonhuman primates.

centrifugation; collagen cross-links; hydroxyproline; Macaca mulatta