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S. Gunda, S. Hariharan, K. Janoria, A.K. Mitra; Mechanism of Corneal Absorption and Aqueous Humor Kinetics of L–Arginine in vivo: Using Topical Infusion Model in Rabbit . Invest. Ophthalmol. Vis. Sci. 2006;47(13):71.
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© ARVO (1962-2015); The Authors (2016-present)
To study the role of neutral and cationic amino acid transporter (B0,+) in corneal transport and aqueous humor kinetics of its model substrate, L–Arginine.
Male New Zealand white rabbits were anaesthetized and linear microdialysis probes were implanted into the anterior chamber of the eye and perfused with isotonic phosphate buffer saline at 2µl/min. A well was placed over the cornea using bonding cement as an adhesive agent. Two hundred micro liters of 2µCi/ml solution of [3H] L–Arginine was placed in the well for 2hrs. After 2hrs the solution and the well were removed. Microdialysis samples were collected every 20 mins and analyzed using liquid scintillation counter. Experiments were repeated in presence of different inhibitors and buffers to ascertain the activity of the transporter.
L–Arginine, a cationic amino acid, has affinity to B0,+ amino acid transporter. So, [3H] L–Arginine was selected to study the functional activity of B0,+ present on the rabbit cornea. Area under the curve (AUC) of [3H] L–Arginine was found to be 351±73.5 pmole*min/ml, which was 8–10 times higher as compared to L–Arginine AUC in presence of 1mM cold L–Arginine (27.4±15.9 pmole*min/ml ) and 1mM BCH (43.83±6.5 pmole*min/ml ) as inhibitors. Tmax values of L–Arginine increased in the presence of inhibitors with a corresponding decrease in Cmax values. A similar pattern was observed in the presence of chloride free buffer indicating the involvement of the B0,+ transporter, present on the corneal epithelium, in L–Arginine transport across rabbit cornea into the aqueous humor.
Functional evidence suggests the presence of B0,+ transporter on the rabbit cornea.
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