Leucine kinetics from (2H3)- and ( sup 13 C)leucine infused simultaneously by gut and vein

Journal Article · Tue Jan 01 00:00:00 EST 1991 · American Journal of Physiology; (USA)

OSTI ID:6249090

Hoerr, R A; Matthews, D E; Bier, D M; Young, V R ^[1]

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1. Massachusetts Institute of Technology, Cambridge (USA)

In amino acid tracer kinetic studies of the fed state, ingested amino acid may be taken up during its initial transit through splanchnic tissues and thus not enter the plasma compartment where tracer is infused. To investigate this possibility, adult human subjects received simultaneous intravenous (iv) and intragastric (ig) leucine tracer infusions, first during a postabsorptive (PA) 4-h primed continuous ig infusion of L-(1-13C)-leucine and L-(5,5,5-2H3)leucine iv, followed on a separate day by a fed infusion, in which an ig infusion of a liquid formula was started 2 h before the tracer infusion and continued throughout the tracer study. Subjects were accustomed to a constant experimental diet supplying 1.5 g protein.kg-1.day-1 and 41-45 kcal.kg-1.day-1 for 7 and 12 days before the PA and fed studies, respectively. For the PA study, plasma enrichment for the ig tracer was 3.34 +/- 0.27 (SE) mol + excess and for the iv tracer it was 4.18 +/- 0.10 (P less than 0.02). Enrichments of alpha-keto-isocaproic acid (KIC) were 3.24 +/- 0.16 (ig) and 3.02 +/- 0.14 (iv), respectively (not significant (NS)). For the fed study, plasma leucine enrichment for the ig tracer was 2.15 +/- 0.14 and for the iv tracer was 2.84 +/- 0.09 (P less than 0.02). KIC enrichments were 2.02 +/- 0.08 (ig) and 2.24 +/- 0.08 (iv), respectively (NS). In the PA study, the ratio of the plasma leucine enrichments for the ig and iv tracers was 0.80 +/- 0.06 and in the fed experiment, 0.76 +/- 0.05, respectively.

• OSTI ID: 6249090
• Journal Information: American Journal of Physiology; (USA), Vol. 260:1 Pt 1; ISSN 0002-9513
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
LEUCINE
METABOLISM
CARBON 13
DEUTERIUM
INTESTINAL ABSORPTION
INTRAVENOUS INJECTION
ISOTOPE DILUTION
TRACER TECHNIQUES
VEINS
ABSORPTION
AMINO ACIDS
BLOOD VESSELS
BODY
CARBON ISOTOPES
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
EVEN-ODD NUCLEI
HYDROGEN ISOTOPES
INJECTION
INTAKE
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
STABLE ISOTOPES
UPTAKE
550501* - Metabolism- Tracer Techniques