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TITLE: Age-related sarcopenia (loss of muscle) in humans is associated with reduced synthetic rates of specific muscle proteins.

AUTHORS: Proctor DN; Balagopal P; Nair KS

AUTHOR AFFILIATION: Endocrine Research Unit, Mayo Clinic and Foundation, Rochester, MN 55905, USA.

SOURCE: J Nutr 1998 Feb;128(2 Suppl):351S-355S. CITATION IDS: PMID: 9478023 UI: 98138510

ABSTRACT: Sarcopenia  of aging is not explained entirely on the basis of age-associated reduced physical activity. Progressive neuromuscular changes and diminishing anabolic hormone levels are thought to contribute to the pathogenesis of sarcopenia. Decline in muscle mass indicates a decline in muscle protein content. Recent studies demonstrated an age-related decline in synthesis rate of mixed muscle proteins, myosin heavy chain and mitochondrial protein. Reductions in myosin heavy chain and mitochondrial protein synthesis rates have been correlated with age-associated decrements in muscle strength and aerobic exercise tolerance, respectively. These changes have been reported as early as 50 y of age and are related to the decline in insulin-like growth factor (IGF)-I (metabolite of HGH), testosterone and dehydroepiandrosterone (DHEA)-sulfate. The declining ability to remodel these important muscle proteins may therefore play a role in the development of muscle wasting, metabolic abnormalities and impaired physical functioning seen in old age.

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