title: Dehydroascorbic acid and ascorbic acid transport systems in the guinea pig ileum.
abstract: The transport properties of dehydroascorbic acid and ascorbic acid in membrane vesicle preparations of guinea pig ileum were evaluated. Na-dependent transport of ascorbic acid in the brush-border membrane was confirmed, and an Na-independent mechanism was found in the basolateral membrane. The electrically neutral oxidized form of vitamin C is transported by an Na-independent mechanism at both cell surfaces. Transport of each substrate is saturable and exhibits cis-inhibition and trans-stimulation in the presence of structural analogues. Additional studies on ascorbate metabolism will be necessary to support a comprehensive model of intestinal handling of vitamin C.
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000031:analogs & derivatives* / Q000378:metabolism*; D001693:Biological Transport, Active; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D003683:Dehydroascorbic Acid / Q000378:metabolism*; D006168:Guinea Pigs; D007082:Ileum / Q000378:metabolism* / Q000648:ultrastructure; D007536:Isomerism; D007700:Kinetics; D008871:Microvilli / Q000378:metabolism / Q000648:ultrastructure; D009994:Osmolar Concentration; D013997:Time Factors
chemical_list: D001205:Ascorbic Acid; D003683:Dehydroascorbic Acid