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Kinetics of L-[1-(13)C]leucine when ingested with free amino acids, unlabeled or intrinsically labeled casein.
- Source :
-
American journal of physiology. Endocrinology and metabolism [Am J Physiol Endocrinol Metab] 2000 Jun; Vol. 278 (6), pp. E1000-9. - Publication Year :
- 2000
-
Abstract
- In two groups of five adults, each adapted to two different dietary regimens for 6 days, the metabolic fate of dietary [1-(13)C]leucine was examined when ingested either together with a mixture of free amino acids simulating casein (extrinsically labeled; condition A), along with the intact casein (extrinsically labeled; condition B), or bound to casein (intrinsically labeled; condition C). Fed state leucine oxidation (Ox), nonoxidative leucine disposal (NOLD), protein breakdown, and splanchnic uptake have been compared using an 8-h oral [1-(13)C]leucine and intravenous [(2)H(3)]leucine tracer protocol while giving eight equal hourly mixed meals. Lower leucine Ox, increased NOLD, and net protein synthesis were found with condition C compared with condition A (19.3 vs. 24.9; 77 vs. 55.8; 18.9 vs. 12.3 micromol. kg(-1). 30 min(-1); P < 0.05). Ox and NOLD did not differ between conditions B and C. Splanchnic leucine uptake calculated from [1-(13)C]- and [(2)H(3)]leucine plasma enrichments was between 24 and 35%. These findings indicate that the form in which leucine is consumed affects its immediate metabolic fate and retention by the body; the implications of these findings for the tracer balance technique and estimation of amino acid requirements are discussed.
- Subjects :
- Adult
Carbon Dioxide analysis
Carbon Isotopes
Deuterium
Diet
Female
Humans
Insulin blood
Keto Acids blood
Kinetics
Leucine blood
Male
Mesentery metabolism
Oxidation-Reduction
Amino Acids administration & dosage
Caseins administration & dosage
Dietary Proteins administration & dosage
Leucine administration & dosage
Leucine pharmacokinetics
Subjects
Details
- Language :
- English
- ISSN :
- 0193-1849
- Volume :
- 278
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- American journal of physiology. Endocrinology and metabolism
- Publication Type :
- Academic Journal
- Accession number :
- 10827001
- Full Text :
- https://doi.org/10.1152/ajpendo.2000.278.6.E1000