Fetoplacental deamination and decarboxylation of leucine

Journal Article · Mon Oct 01 00:00:00 EDT 1990 · American Journal of Physiology; (USA)

OSTI ID:6275191

Loy, G L; Quick, Jr, A N; Hay, Jr, W W; Meschia, G; Battaglia, F C; Fennessey, P V ^[1]

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1. Univ. of Colorado School of Medicine, Denver (USA)

Fetal and placental metabolism of leucine (Leu) and ketoisocaproic acid (KIC) were studied in seven fetal lambs at 132 +/- 1.3-days gestation. Fetal infusions of (1-13C)Leu, (1-14C)Leu, and antipyrine were carried out for 4 h. Uterine and umbilical blood flows were measured using the antipyrine steady-state diffusion technique. Leu and KIC concentrations, (14C)Leu-specific activities, 14CO2, (13C)Leu, and (13C)KIC enrichment (mole percent enrichment) were measured in the maternal artery, uterine vein, and umbilical artery and vein to calculate net fluxes of tracee and tracer molecules between fetus and placenta and between the uteroplacenta and the maternal circulation. There were net Leu and KIC fluxes into the fetus from the placenta with the KIC flux equal to approximately 19% of the combined Leu plus KIC flux. In addition, there was a net KIC flux into the uterine circulation. The fraction of infused tracer Leu escaping the placenta into the mother was small (approximately 6%). By contrast, there was a rapid exchange of tracer Leu carbon between placenta and fetus resulting in a significant flux of labeled KIC from placenta to fetus. Approximately 20% of the infused tracer carbon was converted to CO2 within the fetus. This rate of conversion was greater than 80% of the total fetoplacental conversion rate and significantly higher than the flux of KIC tracer carbon from placenta to fetus. Fetal KIC decarboxylation rate, calculated from the fetal KIC enrichment data, was 2.83 +/- 0.40 mumol.min-1.kg fetus-1 and approximately 60% of the combined net Leu and KIC flux into the fetus from the placenta.

• OSTI ID: 6275191
• Journal Information: American Journal of Physiology; (USA), Vol. 259:4 Pt 1; ISSN 0002-9513
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
FETUSES
BLOOD FLOW
KETO ACIDS
METABOLISM
LEUCINE
CARBON 13
CARBON 14 COMPOUNDS
DEAMINATION
DECARBOXYLATION
ISOTOPE DILUTION
MEMBRANE TRANSPORT
PLACENTA
SHEEP
AMINO ACIDS
ANIMALS
CARBON ISOTOPES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DOMESTIC ANIMALS
EVEN-ODD NUCLEI
FETAL MEMBRANES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
MAMMALS
MEMBRANES
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
RUMINANTS
STABLE ISOTOPES
TRACER TECHNIQUES
VERTEBRATES
550501* - Metabolism- Tracer Techniques