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PURPOSE Neuronal cell death has been reported in retinas of humans with diabetic retinopathy and in diabetic rat models. Little is known about neuronal cell death in mouse models of diabetic retinopathy. This study was designed to determine whether neurons are lost in diabetic mouse retinas and whether the loss involves an apoptotic process. METHODS(More)
The transport of L-carnitine (4-N-trimethylamino-3-hydroxybutyric acid), a compound known to be transported by the organic cation transporter/carnitine transporter OCTN2, was studied in immortalized rat brain endothelial cells (RBE4). The cells were found to take up L-carnitine by a sodium-dependent process. This uptake process was saturable with an(More)
Na+-coupled carboxylate transporters (NaCs) mediate the uptake of tricarboxylic acid cycle intermediates in mammalian tissues. Of these transporters, NaC3 (formerly known as Na+-coupled dicarboxylate transporter 3, NaDC3/SDCT2) and NaC2 (formerly known as Na+-coupled citrate transporter, NaCT) have been shown to be expressed in brain. There is, however,(More)
In the present study, we report on the molecular cloning and functional characterization of mouse NaCT (Na+-coupled citrate transporter), the mouse orthologue of Drosophila Indy. Mouse NaCT consists of 572 amino acids and is highly similar to rat and human NaCTs in primary sequence. The mouse nact gene coding for the transporter is approx. 23 kb long and(More)
PURPOSE The purpose of this investigation was to provide evidence for the expression of the cystine/glutamate transporter (x(c)(-)) in the human retinal pigment epithelial cell line ARPE-19, clone the light chain of the transporter from an ARPE-19 cell cDNA library and study its function, and investigate the regulation of this transporter by nitric oxide(More)
Taurine is an essential amino acid in some mammals and is conditionally essential in humans. Taurine is an abundant component of meat and fish-based foods and has been used as an oral supplement in the treatment of disorders such as cystic fibrosis and hypertension. The purpose of this investigation was to identity the relative contributions of the solute(More)
Although the cerebral accumulation of guanidinoacetate (GAA) contributes to neurological complications in S-adenosylmethionine:guanidinoacetate N-methyltransferase (GAMT) deficiency, how GAA is abnormally distributed in the brain remains unknown. The purpose of this study was to investigate the transport of GAA across the blood-brain barrier (BBB) and in(More)
PURPOSE To determine whether taurine transporter (TauT) activity and expression are regulated by hyperosmolarity in RPE, ganglion, and Müller cells. METHODS Uptake of taurine was measured in ARPE-19 cells cultured in DMEM-F12 medium without or with the addition of 50 mM NaCl or 100 mM mannitol. The kinetics of the transport were analyzed. RT-PCR and(More)
The hPEPT1 cDNA cloned from human intestine (Liang, R., Fei, Y.-J., Prasad, P. D., Ramamoorthy, S., Han, H., Yang-Feng, T. L., Hediger, M. A., Ganapathy, V., and Leibach, F. H. (1995) J. Biol. Chem. 270, 6456-6463) encodes a H+/oligopeptide cotransporter. Using two-microelectrode voltage-clamp in Xenopus oocytes expressing hPEPT1, we have investigated the(More)
PURPOSE Retinal pigment epithelium (RPE) expresses GPR109A, a receptor for the vitamin niacin and the ketone body β-hydroxybutyrate (β-HB). Because diabetes results in elevated levels of β-HB, here we studied expression of the receptor in diabetic retina. We also investigated its functional relevance in RPE. METHODS Retinal expression of GPR109A in(More)