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Functional heteroge...
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Ljungqvist, Olle,1954-Karolinska Institutet
(författare)
Functional heterogeneity of leucine pools in human skeletal muscle
- Artikel/kapitelEngelska1997
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HighWire Press,1997
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LIBRIS-ID:oai:DiVA.org:oru-64373
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https://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-64373URI
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https://doi.org/10.1152/ajpendo.1997.273.3.E564DOI
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http://kipublications.ki.se/Default.aspx?queryparsed=id:114855313URI
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Språk:engelska
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Sammanfattning på:engelska
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Ämneskategori:art swepub-publicationtype
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Funding Agencies:NCRR NIH HHS NIDDK NIH HHS
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Current models to measure muscle protein synthesis in humans assume a homogeneous intracellular amino acid pool. This assumption was tested by measuring the isotopic enrichment of leucine and its transamination product alpha-ketoisocaproate (KIC) in plasma and muscle tissue fluid and comparing them with that of leucyl-tRNA during a continuous infusion of L-[1-13C]leucine in 12 healthy subjects. Six subjects were studied twice while drinking a carbohydrate (0.42 kcal/kg) drink every 20 min for 11 h or the same volume of water. Six others took an isocaloric mixed meal providing 14 mg protein/kg every 20 min and water. Enrichment of plasma and tissue fluid KIC and plasma leucine was consistently higher than that of leucyl-tRNA and tissue fluid leucine (P < 0.01), whereas the enrichment of leucyl-tRNA was equivalent to that of tissue fluid leucine in all experiments. Furthermore, the ratio of enrichment of leucyl-tRNA to that of plasma leucine and KIC decreased after the mixed meal, whereas that of leucyl-tRNA to tissue fluid leucine remained constant. The enrichment of KIC was closer (approximately 17% lower) to that of plasma leucine than that of leucyl-tRNA (approximately 43% higher), indicating that the transamination pool derived more leucine from extracellular sources than the acylation pool. We conclude that the use of plasma KIC enrichment as a surrogate measure of leucyl-tRNA enrichment substantially underestimates muscle protein synthetic rates in humans, whereas tissue fluid leucine enrichment is a valid surrogate measure. In addition, the differences in enrichment of leucyl-tRNA and KIC support a regulated cytoplasmic trafficking of leucine in muscle cells.
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Persson, M.Endocrine Research Unit, Division of Endocrinology and Metabolism, Mayo Clinic and Mayo Foundation, Rochester, MN, United States
(författare)
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Ford, G. C.Endocrine Research Unit, Division of Endocrinology and Metabolism, Mayo Clinic and Mayo Foundation, Rochester, MN, United States
(författare)
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Nair, K. S.Endocrine Research Unit, Division of Endocrinology and Metabolism, Mayo Clinic and Mayo Foundation, Rochester, MN, United States
(författare)
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Karolinska InstitutetEndocrine Research Unit, Division of Endocrinology and Metabolism, Mayo Clinic and Mayo Foundation, Rochester, MN, United States
(creator_code:org_t)
Sammanhörande titlar
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Ingår i:American Journal of Physiology: HighWire Press273:3 Pt 1, s. E564-E5700002-95132163-5773
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