Evaluation of the isotopic equilibrium between lactate and pyruvate

Journal Article · Fri Apr 01 04:00:00 EST 1988 · American Journal of Physiology; (USA)

OSTI ID:7013674

Wolfe, R R; Jahoor, F; Miyoshi, H ^[1]

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1. Univ. of Texas Medical Branch, Galveston (USA)

When an isotopic tracer is infused for the purpose of determining the rate of turnover or oxidation of a substrate, it is assumed that the resulting isotopic enrichment of the trace will reflect kinetics of only the pool of interest. However, this may not be the case when carbon-labeled lactate is infused, since rapid isotopic exchange with the intracellular pyruvate and alanine pools could potentially occur. Therefore the authors have determined the extent of isotopic exchange occurring during the infusion of (3-{sup 13}C)lactate into six anesthetized dogs. In the steady state, pyruvate enrichment was 91 {plus minus} 2.2% of the lactate enrichment, and alanine enrichment was 81 {plus minus} 3.3% of the pyruvate enrichment and 72 {plus minus} 2.6% of the lactate enrichment. In contrast, when (3-{sup 13}C)alanine was infused, pyruvate (and lactate) enrichment was 9.9% of the alanine enrichment. They therefore conclude that there is rapid isotopic equilibration between lactate and pyruvate but that interaction with alanine reflects the true metabolic flux rates, rather than isotopic exchange. Consequently, lactate kinetics, as traditionally determined, more accurately reflect whole body pyruvate kinetics.

• OSTI ID: 7013674
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 254:4; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALANINES
AMINO ACIDS
ANIMALS
BIOLOGICAL MATERIALS
BLOOD
BODY FLUIDS
CARBON 13
CARBON ISOTOPES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DOGS
EVEN-ODD NUCLEI
HYDROXY ACIDS
INFUSION
INTAKE
ISOTOPE APPLICATIONS
ISOTOPES
ISOTOPIC EXCHANGE
KETO ACIDS
LABELLED COMPOUNDS
LACTIC ACID
LIGHT NUCLEI
MAMMALS
MATERIALS
METABOLISM
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDATION
PYRUVIC ACID
RADIONUCLIDE KINETICS
SAMPLING
STABLE ISOTOPES
SUBSTRATES
TRACER TECHNIQUES
VERTEBRATES