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Title: Fetoplacental deamination and decarboxylation of leucine

Abstract

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 thanmore » 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.« less

Authors:
; ; ; ; ;  [1]
  1. Univ. of Colorado School of Medicine, Denver (USA)
Publication Date:
OSTI Identifier:
6275191
Resource Type:
Journal Article
Journal Name:
American Journal of Physiology; (USA)
Additional Journal Information:
Journal Volume: 259:4 Pt 1; Journal ID: ISSN 0002-9513
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

Loy, G L, Quick, Jr, A N, Hay, Jr, W W, Meschia, G, Battaglia, F C, and Fennessey, P V. Fetoplacental deamination and decarboxylation of leucine. United States: N. p., 1990. Web.
Loy, G L, Quick, Jr, A N, Hay, Jr, W W, Meschia, G, Battaglia, F C, & Fennessey, P V. Fetoplacental deamination and decarboxylation of leucine. United States.
Loy, G L, Quick, Jr, A N, Hay, Jr, W W, Meschia, G, Battaglia, F C, and Fennessey, P V. 1990. "Fetoplacental deamination and decarboxylation of leucine". United States.
@article{osti_6275191,
title = {Fetoplacental deamination and decarboxylation of leucine},
author = {Loy, G L and Quick, Jr, A N and Hay, Jr, W W and Meschia, G and Battaglia, F C and Fennessey, P V},
abstractNote = {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.},
doi = {},
url = {https://www.osti.gov/biblio/6275191}, journal = {American Journal of Physiology; (USA)},
issn = {0002-9513},
number = ,
volume = 259:4 Pt 1,
place = {United States},
year = {Mon Oct 01 00:00:00 EDT 1990},
month = {Mon Oct 01 00:00:00 EDT 1990}
}