Na+-independent dehydro-L-ascorbic acid uptake in renal brush-border membrane vesicles.
A membrane preparation enriched in the brush-border component of the plasma membrane was isolated from rat renal superficial cortex by a divalent cation precipitation procedure. Uptake of dehydro-L-ascorbic acid, the oxidized form of L-ascorbic acid, by the brush-border membrane vesicles was studied. The uptake mechanism was found to be sodium-independent and insensitive to the trans-membrane electrical potential difference. Uptake was saturable and subject to cis-inhibition. Concentrative uptake was demonstrated only under conditions of trans-stimulation by structural analogs. The results suggest a mechanism of facilitated diffusion for the uptake of dehydro-L-ascorbic acid in renal brush-border membranes.
D000818:Animals; D000838:Anions / Q000502:physiology; D001205:Ascorbic Acid / Q000031:analogs & derivatives*; D001692:Biological Transport; D002474:Cell-Free System; D003683:Dehydroascorbic Acid / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D007668:Kidney / Q000378:metabolism*; D007700:Kinetics; D008564:Membrane Potentials; D008871:Microvilli / Q000378:metabolism; D011188:Potassium / Q000502:physiology; D011485:Protein Binding; D051381:Rats; D013237:Stereoisomerism
D000838:Anions; D005947:Glucose; D001205:Ascorbic Acid; D011188:Potassium; D003683:Dehydroascorbic Acid