title: Alterations in the activity of placental amino acid transporters in pregnancies complicated by diabetes.
abstract: Alterations in placental transport may contribute to accelerated fetal growth in pregnancies complicated by diabetes. We studied the activity of the syncytiotrophoblast amino acid transporter system A and the transport of the essential amino acids leucine, lysine, and taurine. Syncytiotrophoblast microvillous plasma membranes (MVMs) and basal plasma membranes (BMs) were isolated from placentas obtained from normal pregnancies and pregnancies complicated by gestational diabetes mellitus (GDM) and type 1 diabetes, with and without large-for-gestational-age (LGA) fetuses. Amino acid transport was assessed using radio-labeled substrates and rapid filtration techniques. System A activity in MVM was increased (65-80%, P < 0.05) in all groups with diabetes independent of fetal overgrowth. However, MVM system A activity was unaffected in placentas of normal pregnancies with LGA fetuses. MVM leucine transport was increased in the GDM/LGA group. In BMs, amino acid transport was unaffected by diabetes. In conclusion, diabetes in pregnancy is associated with an increased system A activity in MVM, and MVM leucine transport is increased in the GDM/LGA group. We suggest that these changes result in an increased uptake of neutral amino acids across MVM, which may be used in placental metabolism or be delivered to the fetus. The increased MVM leucine uptake in the GDM/LGA group may contribute to accelerated fetal growth in these patients.
authors.affiliation: Department of Physiology and Pharmacology, the Perinatal Center, Göteborg University, Box 432, S-405 30 Göteborg, Sweden. thomas.jansson@fysiologi.gu.se
authors.forename: Thomas
authors.initials: T
authors.lastname: Jansson
authors.forename: Ylva
authors.initials: Y
authors.lastname: Ekstrand
authors.forename: Caroline
authors.initials: C
authors.lastname: Björn
authors.forename: Margareta
authors.initials: M
authors.lastname: Wennergren
authors.forename: Theresa L
authors.initials: TL
authors.lastname: Powell
mesh_terms: D000328:Adult; D026905:Amino Acid Transport Systems / Q000378:metabolism*; D001724:Birth Weight; D002462:Cell Membrane / Q000378:metabolism; D016640:Diabetes, Gestational / Q000378:metabolism*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008423:Maternal Age; D009929:Organ Size; D010920:Placenta / Q000033:anatomy & histology / Q000378:metabolism*; D011247:Pregnancy; D011254:Pregnancy in Diabetics / Q000378:metabolism*; D018566:Pregnancy, High-Risk; D012016:Reference Values
chemical_list: D026905:Amino Acid Transport Systems