Transport and metabolism of amino acids in placenta.
In all mammalian species, the 20 amino acids of the genetic code are required for net protein accretion. The nutritional supply of amino acids for growth is defined as the net umbilical uptake of amino acids, representing the net transfer from maternal circulation, through the placenta and then to the fetus, of essential and non-essential amino acids. In considering the primary role of the placenta in the delivery of amino acids to the fetus for metabolism, it is important to consider the multiplicity of factors that may affect these overall delivery rates, including the activity and location of amino acid transporter systems, changes in these systems as gestation advances, effects of changes in placental surface area, uteroplacental blood flows, and maternal concentrations of amino acids. In this review, we discuss placental amino acid transport, the systems and their associated proteins, umbilical uptake data in animal and human studies, and amino acid transport in fetal growth restriction. Additionally, we discuss the current pool of thought concerning the mechanisms of placental amino acid transport as generated through in vitro vesicle studies and how they relate to the in vivo fluxes of animal studies. Finally, we discuss fetoplacental amino acid metabolism and specifically interorgan exchange.
Regnault
Timothy R H
TR
Department of Pediatrics, Division of Perinatal Medicine, University of Colorado Health Sciences Center, Aurora, CO 80010, USA. tim.regnault@uchsc.edu
de Vrijer
Barbra
B
Battaglia
Frederick C
FC
D026905:Amino Acid Transport Systems / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D005317:Fetal Growth Retardation / Q000378:metabolism; D005333:Fetus / Q000378:metabolism; D006801:Humans; D010920:Placenta / Q000378:metabolism*; D012756:Sheep / Q000378:metabolism; D014470:Umbilical Cord / Q000378:metabolism
D026905:Amino Acid Transport Systems; D000596:Amino Acids