Document Detail

Facilitated transporters mediate net efflux of amino acids to the fetus across the basal membrane of the placental syncytiotrophoblast.
MedLine Citation:
PMID:  21224231     Owner:  NLM     Status:  MEDLINE    
Fetal growth depends on placental transfer of amino acids from maternal to fetal blood. The mechanisms of net amino acid efflux across the basal membrane (BM) of the placental syncytiotrophoblast to the fetus, although vital for amino acid transport, are poorly understood. We examined the hypothesis that facilitated diffusion by the amino acid transporters TAT1, LAT3 and LAT4 plays an important role in this process, with possible effects on fetal growth. Amino acid transfer was measured in isolated perfused human placental cotyledons (n = 5 per experiment) using techniques which distinguish between different transport processes. Placental TAT1, LAT3 and LAT4 proteins were measured, and mRNA expression levels (measured using real-time quantitative-PCR) were related to fetal and neonatal anthropometry and dual-energy X-ray absorptiometry measurements of neonatal lean mass in 102 Southampton Women's Survey (SWS) infants. Under conditions preventing transport by amino acid exchangers, all amino acids appearing in the fetal circulation were substrates of TAT1, LAT3 or LAT4. Western blots demonstrated the presence of TAT1, LAT3 and LAT4 in placental BM preparations. Placental TAT1 and LAT3 mRNA expression were positively associated with measures of fetal growth in SWS infants (P < 0.05). We provide evidence that the efflux transporters TAT1, LAT3 and LAT4 are present in the human placental BM, and may play an important role in the net efflux of amino acids to the fetus. Unlike other transporters they can increase fetal amino acid concentrations. Consistent with a role in placental amino acid transfer capacity and fetal growth TAT1 and LAT3 mRNA expression showed positive associations with infant size at birth.
J K Cleal; J D Glazier; G Ntani; S R Crozier; P E Day; N C Harvey; S M Robinson; C Cooper; K M Godfrey; M A Hanson; R M Lewis
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2011-01-04
Journal Detail:
Title:  The Journal of physiology     Volume:  589     ISSN:  1469-7793     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-04-13     Completed Date:  2012-03-06     Revised Date:  2014-03-19    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  987-97     Citation Subset:  IM    
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MeSH Terms
Amino Acid Transport Systems / physiology*
Amino Acid Transport Systems, Basic / physiology
Amino Acid Transport Systems, Neutral / physiology
Amino Acids / metabolism*
Data Collection / methods
Fetus / blood supply,  metabolism*
Infant, Newborn
Maternal-Fetal Exchange / physiology*
Placenta / blood supply,  metabolism*
Trophoblasts / metabolism*
Young Adult
Grant Support
MC_UP_A620_1014//Medical Research Council; MC_UP_A620_1017//Medical Research Council; SOUDIBRU-2008-1//Department of Health; //British Heart Foundation; //Medical Research Council
Reg. No./Substance:
0/Amino Acid Transport Systems; 0/Amino Acid Transport Systems, Basic; 0/Amino Acid Transport Systems, Neutral; 0/Amino Acids; 0/SLC16A10 protein, human; 0/SLC7A6 protein, human

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