May 2003
Volume 44, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2003
Essential Role of GLUT1 in the Inner Blood-retinal Barrier Transport of Vitamin C
Author Affiliations & Notes
  • K. Hosoya
    Dept Pharmaceutical Sci, Toayama Med & Pharm Univ, Toyama, Japan
  • A. Minamizono
    Dept Pharmaceutical Sci, Toayama Med & Pharm Univ, Toyama, Japan
  • K. Katayama
    Dept Pharmaceutical Sci, Toayama Med & Pharm Univ, Toyama, Japan
  • S. Ohtsuki
    Grad School of Pharm Sci, Tohoku Univ, Sendai, Japan
  • T. Terasaki
    New Industry Creation Hatchery Center, Tohoku Univ, Sendai, Japan
  • M. Tomi
    New Industry Creation Hatchery Center, Tohoku Univ, Sendai, Japan
  • CREST of Japan Science and Technology Corp
    New Industry Creation Hatchery Center, Tohoku Univ, Sendai, Japan
Investigative Ophthalmology & Visual Science May 2003, Vol.44, 3446. doi:
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      K. Hosoya, A. Minamizono, K. Katayama, S. Ohtsuki, T. Terasaki, M. Tomi, CREST of Japan Science and Technology Corp; Essential Role of GLUT1 in the Inner Blood-retinal Barrier Transport of Vitamin C . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3446.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Abstract: : Purpose: Vitamin C (ascorbic acid) plays a key role in protecting the retina from light-induced oxidative stress. Dehydroascorbic acid (DHAA), which is an oxidized form of vitamin C, is a substrate for glucose transporter 1 (GLUT1), which is expressed at the inner blood-retinal barrier (iBRB). The purpose of this study was to elucidate the DHAA transport mechanism at the iBRB. Methods:[14C]DHAA transport to the rat retina was evaluated using an in vivo integration plot analysis. The conditionally immortalized rat retinal capillary endothelial cell line (TR-iBRB), which expresses GLUT1, was used as an in vitro model for the iBRB. [14C]DHAA was generated in all experiments by incubating [14C]ascorbic acid (AA) with ascorbate oxidase. Results: In the rat retina, the apparent influx clearance of [14C]DHAA was 38-fold greater than that of [14C]AA. [14C]DHAA uptake by TR-iBRB cells was Na+-independent and concentration-dependent with a Michaelis constant of 93 uM. The initial uptake rate of [14C]DHAA by TR-iBRB cells was 37-fold greater than that of [14C]AA. [14C]DHAA uptake was inhibited by more than 50% in the presence of D-glucose, 3-O-methyl-D-glucose, 2-deoxyglucose, cytochalasin B, and phloretin, which are substrates and/or inhibitors of GLUT1. Conclusions:These findings suggest that transport of vitamin C into the retina is mediated as DHAA via GLUT1 at the iBRB. It allows a better understanding of the function of the iBRB with regard to the protecting neural retina.

Keywords: retina • oxidation/oxidative or free radical damage • vascular cells 
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