Cationic amino acid transporter 1-mediated l-arginine transport at the inner blood-retinal barrier

Masatoshi Tomi, Naohisa Kitade, Shirou Hirose, Noriko Yokota, Shin Ichi Akanuma, Masanori Tachikawa, Ken Ichi Hosoya

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

The purpose of this study was to identify the transporter mediating l-arginine transport at the inner blood-retinal barrier (BRB). The apparent uptake clearance of [3H]l-arginine into the rat retina was found to be 118 μL/(min·g retina), supporting a carrier-mediated influx transport of l-arginine at the BRB. [3H]l-Arginine uptake by a conditionally immortalized rat retinal capillary endothelial cell line (TR-iBRB2 cells), used as an in vitro model of the inner BRB, was primarily an Na +-independent and saturable process with Michaelis-Menten constants of 11.2 μM and 530 μM. This process was inhibited by rat cationic amino acid transporter (CAT) 1-specific small interfering RNA as well as substrates of CATs, l-arginine, l-lysine, and l-ornithine. The expression of cationic amino acid transporter (CAT) 1 mRNA was 25.9- and 796-fold greater than that of CAT3 in TR-iBRB2 and magnetically isolated rat retinal vascular endothelial cells, respectively. The expression of CAT1 protein was detected in TR-iBRB2 cells and immunostaining of CAT1 was observed along the rat retinal capillaries. In conclusion, CAT1 is localized in retinal capillary endothelial cells and at least in part mediates l-arginine transport at the inner BRB. This process seems to be closely involved in visual functions by supplying precursors of biologically important molecules like nitric oxide in the neural retina.

Original languageEnglish
Pages (from-to)716-725
Number of pages10
JournalJournal of Neurochemistry
Volume111
Issue number3
DOIs
Publication statusPublished - 2009 Nov 1
Externally publishedYes

Keywords

  • Arginine
  • Capillary endothelial cells
  • Cationic amino acid transporter
  • Inner blood-retinal barrier
  • Retina
  • Transport

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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