Sodium-dependent ascorbic and dehydroascorbic acid uptake by SV-40-transformed retinal pigment epithelial cells

K. W. Lam, H. S. Yu, R. D. Glickman, T. Lin

Research output: Contribution to journalArticle

12 Scopus citations


The present data confirmed previous studies with other cell types that ascorbic acid and dehydroascorbic acid are transported through different transporters into SV-40-transformed retinal pigment epithelial cells. These experiments were performed on cells grown on 96-well culture plates. Ascorbic acid was taken up into the cell by a high-affinity transporter with Km = 0.041 mmol/1 and a low Vmax of 2.74 pmol/min/well. Dehydroascorbic acid was taken up by a low-affinity transporter with Km = 5.67 mmol/1; however, the Vmax was 325.5 pmol/min/well. The uptake of both ascorbic acid and dehydroascorbic acid was dependent on the sodium concentration. The uptake of ascorbic acid does not involve oxidation-reaction steps because the uptake of [l4C]-ascorbate was unaffected by the presence of an excess amount of unlabelled dehydroascorbic acid.

Original languageEnglish (US)
Pages (from-to)100-107
Number of pages8
JournalOphthalmic Research
Issue number2
Publication statusPublished - Jan 1 1993



  • Active transport
  • Ascorbate
  • Dehydroascorbate
  • Oxidative reduction
  • Retinal pigment epithelium
  • Sodium

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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