Leucine metabolism during fasting and exercise.
Journal Article (Journal Article)
Whole body leucine kinetics were examined in seven healthy young men while in a 14-h postabsorptive state (PAS) and after a 3.5-day fast (FS). Subjects received a primed constant intravenous infusion of L-[1-13C]leucine while resting for 3 h and then while exercising on a cycle ergometer at 45% maximal O2 uptake to exhaustion. Blood samples drawn during isotopic steady state were analyzed for 13C enrichment of leucine and alpha-ketoisocaproic acid, and expired gas samples were analyzed for 13CO2. Resting leucine flux was higher in the FS, and there was a slight increase in leucine oxidation. During exercise, leucine flux did not differ between PAS and FS but leucine oxidation rose markedly. In the FS, leucine oxidation was 25 +/- 7 (SD) mumol.kg-1.h-1 at rest and rose to 75 +/- 21 mumol.kg-1.h-1 during exercise; in the PAS, oxidation was 20 +/- 5 mumol.kg-1.h-1 at rest and 52 +/- 17 mumol.kg-1.h-1 during exercise. These data indicate that the high rate of leucine oxidation previously found during exercise was increased further by a 3.5-day fast.
Full Text
Duke Authors
Cited Authors
- Knapik, J; Meredith, C; Jones, B; Fielding, R; Young, V; Evans, W
Published Date
- January 1, 1991
Published In
Volume / Issue
- 70 / 1
Start / End Page
- 43 - 47
PubMed ID
- 2010401
International Standard Serial Number (ISSN)
- 8750-7587
Digital Object Identifier (DOI)
- 10.1152/jappl.1991.70.1.43
Language
- eng
Conference Location
- United States