Identification and Characterization of a Na⁺-Dependent Neutral Amino Acid Transporter, ASCT1, in Rabbit Corneal Epithelial Cell Culture and Rabbit Cornea

Abstract

L-Alanine, the chosen model substrate, was actively transported by Na+-dependent, neutral amino acid exchanger ASCT1, which was identified and functionally characterized on rPCEC cells and rabbit cornea.

Novel Strategies for Anterior Segment Ocular Drug Delivery

“…[62][63][64] A series of amino acid prodrugs, including alanine-ACV, serine-ACV (SACV), isoleucine-ACV, and g-glutamate-ACV (EACV), were evaluated for in vivo corneal absorption in rabbits. Among these amino acid prodrugs, enhanced stability of SACV resulted in higher area under the curve (AUC), Cmax, and Clast values in comparison to ACV.…”

Transporters and receptors in the anterior segment of the eye

“…Rathore and Gupta [14] reported the functional characterization of l -tryptophan transport across the mammalian cornea, in ex vivo transport studies. Mitra's group has also identifi ed and reported the presence of NAAT (ASCT1 or SLC1A4) and Na + -dependent cationic and neutral AAT, B 0+ , in rabbit primary corneal epithelial cells, rabbit corneal epithelium and human cornea at the RNA level [12,15]. In vitro uptake studies in rabbit primary corneal epithelial cells with l -alanine appeared to be Na + -dependent and saturable kinetics with a K m and V max of 0.71 m m and 0.84 μ m /min/mg protein, respectively.…”

“…They use an electrochemical gradient to translocate substances across the cell L -phenylalanine, L -arginine, L -alanine, serine, thyrosine, cysteine, L -tryptophan [12][13][14][15] OLIGPEPTIDE transporter…”

Virus Diagnostics and Antiviral Therapy in Acute Retinal Necrosis (ARN)

“…Valaciclovir is the valyl ester of aciclovir, which is quickly taken up into enterocytes after oral administration via enteric aminoacid transport systems and which is then hydrolyzed to the active prodrug aciclovir (Granero & Amidon, 2006;Katragadda et al, 2005). The oral bioavailability of valaciclovir of 54% is three times higher than that of aciclovir (Soul-Lawton et al, 1995).…”