title: [Studies on L-glutamate transport mechanism in human placental trophoblast microvilli membrane vesicles].
abstract: The uptake of L-glutamate in brush border (microvilli) vesicles prepared from human term placenta was studied using the rapid filtration technique. The uptake of L-glutamate into the vesicles occurred osmotically, and preincubation with L-glutamate increased the uptake of amino acid. These findings indicate that the uptake of L-glutamate by placental trophoblast brush border membranes represents the transport into membrane vesicles. A Na+ electrochemical gradient (extravesicular greater than intravesicular) stimulated the initial rate of L-glutamate uptake about three times. The initial rate of transport exhibited saturation kinetics with respect to the L-glutamate concentration; an apparent Km of 0.15 mM and V max of 70 pmol/mg protein in 20 seconds were calculated. The uptake of L-glutamate into the vesicles was competitively inhibited by L-glutamate and L-cysteate (acidic amino acid). These results indicate that a Na-dependent acidic amino acid specific transport system exists in the placental trophoblast microvilli membrane. These results indicate that the transport of L-glutamate across the placental microvilli membrane is sodium-dependent and carrier mediated.
mesh_terms: D001224:Aspartic Acid / Q000494:pharmacology; D001692:Biological Transport; D002478:Cells, Cultured; D005260:Female; D005971:Glutamates / Q000378:metabolism*; D006801:Humans; D007477:Ions; D008431:Maternal-Fetal Exchange; D008871:Microvilli / Q000378:metabolism; D009940:Organoids / Q000378:metabolism; D011247:Pregnancy; D012964:Sodium / Q000378:metabolism; D014327:Trophoblasts / Q000378:metabolism*
chemical_list: D005971:Glutamates; D007477:Ions; D001224:Aspartic Acid; D012964:Sodium