Human muscle protein turnover - why is it so variable?

[Mike Bikov]

J Appl Physiol. 2010 Nov 25. [Epub ahead of print]
Human muscle protein turnover - why is it so variable?

Smith GI, Patterson BW, Mittendorfer B.

1Washington University in St Louis.
Abstract

We undertook a comprehensive review of the literature to unravel the nature for the variability in the reported rate of human muscle protein synthesis. We analyzed the results from studies that report the protein fractional synthesis rate (FSR) in the vastus lateralis in healthy, non obese, untrained adults ≤50 y in the postabsorptive state at rest by using the primed, constant tracer amino acid infusion method according to experimental design characteristics. We hypothesized that if the variability is methodological (rather than physiological) in nature, systematic clustering of FSR values would be evident, and outliers would become apparent. Overall, as expected, the mixed muscle protein FSR values were significantly (P<0.001) greater when using the muscle vs. the plasma free amino acid enrichment as the surrogate precursor pool enrichment and the average mixed muscle protein FSR values were significantly greater (P=0.05) than the myofibrillar/myosin heavy chain FSR values. The within study variability (i.e., population variance) was somewhat smaller in studies that used plasma amino acid/ketoacid enrichments vs. the muscle free amino acid enrichment (~24% vs. ~31%) but this was not apparent in all circumstances. Furthermore, the between study consistency of measured FSR values (i.e., inter-quartile range) was inversely correlated with the average duration between biopsies. Aside from that, the variation in reported FSR values could not be explained by differences in the experimental design and analytical methods and none of the most commonly used approaches stood out as clearly superior in terms of consistency of results and/or within study variability. We conclude that the variability in reported values is in part due to: i) differences in experimental design (e.g., choice of precursor pool) and ii) considerable within subject variability. The summary of the results from our analysis can be used as guidelines for "normal" average basal FSR values at rest.

PMID: 21109595​

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[ANIMAL16]

תוכל להסביר ב 2 3 משפטים על מה זה מדבר?

 

[Mike Bikov]

לא, כי אני לא יודע מה אתה מבין ומה אתה לא מבין מהמחקר, תהיה יותר ספציפי. אי אפשר להסביר פה את כל המושגים כמו FSR, אקטין/מיוזין או מה זה בכלל סינטזת חלבון.