[Human placental glutathione transport mechanism].
The placental transport mechanism of glutathione (GSH) was investigated using microvillous membrane vesicles prepared from human term placenta. Using (3H-glycine)-labeled-GSH, it was clarified that GSH in the extravesicular compartment of placental microvillous membranes was rapidly degraded by gamma-GTP (gamma-glutamyltranspeptidase) and resulting amino acid, and 3H-labeled-glycine was actively transported via a sodium cotransport system. AT-125 treated microvillous membrane vesicles almost entirely lost its gamma-GTP activity, and showed intact GSH transport. Using AT-125 treated microvillous membrane vesicles, it was revealed that GSH was transported across the microvillous membrane as an anion via a membrane potential-dependent mechanism. These results indicated that gamma-GTP which existed in microvillous membrane played a role in GSH metabolism and that intracellular GSH was translocated out of the syncythiotrophoblast cell into the maternal blood space via a specific carrier in microvillous membrane because the GSH concentration was higher in intracellular than extracellular and extracellular membrane potential was positively charged.
D001693:Biological Transport, Active; D005260:Female; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007555:Isoxazoles / Q000494:pharmacology; D008564:Membrane Potentials; D008871:Microvilli / Q000378:metabolism; D009997:Osmotic Pressure; D010920:Placenta / Q000187:drug effects / Q000378:metabolism*; D011247:Pregnancy; D012964:Sodium / Q000378:metabolism; D005723:gamma-Glutamyltransferase / Q000378:metabolism
D007555:Isoxazoles; D012964:Sodium; D005723:gamma-Glutamyltransferase; D005978:Glutathione; C006303:acivicin