Skeletal muscle proteolysis in response to short-term unloading in humans

• Skeletal muscle atrophy is evident after muscle disuse, unloading,or spaceflight and results from decreased protein content asa consequence of decreased protein synthesis, increased proteinbreakdown or both. At this time, there are essentially no humandata describing proteolysis in skeletal muscle undergoing atrophyon Earth or in space, primarily due to lack of valid and accuratemethodology. This particular study aimed at assessing the effectsof short-term unloading on the muscle contractile proteolysisrate. Eight men were subjected to 72-h unilateral lower limbsuspension (ULLS) and intramuscular interstitial levels of thenaturally occurring proteolytic tracer 3-methylhistidine (3MH)were measured by means of microdialysis before and on completionof this intervention. The 3MH concentration following 72-h ULLS(2.01 ± 0.22 nmol/ml) was 44% higher (P < 0.05) thanbefore ULLS (1.56 ± 0.20 nmol/ml). The present experimentalmodel and the employed method determining 3MH in microdialysatespresent a promising tool for monitoring skeletal muscle proteolysisor metabolism of specific muscles during conditions resultingin atrophy caused by, e.g., disuse and real or simulated microgravity.This study provides evidence that the atrophic processes areevoked rapidly and within 72 h of unloading and suggests thatcountermeasures should be employed in the early stages of spacemissions to offset or prevent muscle loss during the periodwhen the rate of muscle atrophy is the highest.  

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Hälsovetenskap -- Idrottsvetenskap (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Health Sciences -- Sport and Fitness Sciences (hsv//eng)

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Idrottsvetenskap

Sports

Idrott

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