title: Developmental increases in glucose transporter concentration in the sheep placenta.
abstract: To explore the molecular basis for the gestational increase in glucose transport capacity of the sheep placenta in vivo, placentas from twin-pregnant ewes at days 75, 110, and 140 postcoitus (n = 6/group) were analyzed for glucose transporter (GT) concentration. Concentration (pmol/mg protein) of D-glucose-inhibitable binding sites, measured by [3H]cytochalasin B binding analysis, increased 3.4 times from mid- to late pregnancy. Concurrently, abundance of GLUT-1 and GLUT-3 protein, measured by immunoblotting with specific polyclonal antibodies, increased 2.3 and 2.9 times, respectively, while abundance of GLUT-1 and GLUT-3 mRNA, measured by Northern blotting, increased 1.8 and 3.9 times, respectively. GLUT-4 protein was undetectable at all stages of pregnancy. Quantitative immunoblotting indicated that GLUT-1 accounted for 86.8 +/- 1.6% at day 75 and 56.1 +/- 4.1% at day 140 of total cytochalasin B binding sites. Thus increases in GT concentration explain much of the gestational increase in glucose transfer capacity observed in vivo. The gestational decline in relative contribution of GLUT-1 to cytochalasin binding, together with the greater developmental increases in GLUT-3 mRNA and protein, further suggests that the relative importance of GLUT-3 increases with gestational age.
authors.affiliation: Department of Animal Science, Cornell University, Ithaca, New York 14853, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Ehrhardt
authors.forename: A W
authors.initials: AW
authors.lastname: Bell
mesh_terms: D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism; D002417:Cattle; D003571:Cytochalasin B / Q000378:metabolism; D004910:Erythrocyte Membrane / Q000378:metabolism; D005260:Female; D005865:Gestational Age; D005947:Glucose / Q000378:metabolism; D051272:Glucose Transporter Type 1; D051274:Glucose Transporter Type 3; D006801:Humans; D007700:Kinetics; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis / Q000378:metabolism*; D009419:Nerve Tissue Proteins; D009928:Organ Specificity; D010920:Placenta / Q000378:metabolism / Q000502:physiology*; D011247:Pregnancy; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012756:Sheep; D013045:Species Specificity; D013997:Time Factors; D014158:Transcription, Genetic; D014427:Twins
chemical_list: D051272:Glucose Transporter Type 1; D051274:Glucose Transporter Type 3; D009004:Monosaccharide Transport Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; C495677:SLC2A1 protein, human; C495687:SLC2A3 protein, human; C495679:Slc2a1 protein, rat; C495690:Slc2a3 protein, rat; D003571:Cytochalasin B; D005947:Glucose