Abstract
Abstract: :
Purpose: Taurine, the most abundant amino acid in the retina, may play a role in osmoregulating and modulating antioxidant. The purpose of this study was to characterize taurine transport and regulation of taurine transporter (TAUT) at the inner blood-retinal barrier (iBRB). Methods: The conditionally immortalized retinal capillary endothelial cell line (TR-iBRB) was used as an in vitro model for the iBRB. TR-iBRB cells were cultured at 33C and [3H]taurine uptake was measured at 37C. The quantitative real-time PCR was performed to determine the mRNA level in the cells. Results: RT-PCR and Western blot analysis indicated that TAUT is expressed in TR-iBRB cells. [3H]Taurine uptake by TR-iBRB cells was a temperature-, Na+-, and Cl- -dependent manner. It was concentration-dependent with a Km of 22.2 µM and inhibited by ß-alanine, hypotaurine, and taurocyamine. The quantitative real-time PCR revealed an increase of TAUT under the hypertonic conditions. Conclusion: TAUT mediates taurine transport at the iBRB and is regulated under pathological conditions.
Keywords: 595 taurine • 556 retina: neurochemistry • 446 ion transporters