Taurine transport in cultured choroid plexus

Purpose. Taurine, a beta-amino acid, is a neuromodulator which interacts functionally with the glycinergic, GABAergic, cholinegic and adrenergic systems. Although a continuous cell culture model is not available for the choroid plexus epithelia, we recently described a primary cell culture of rabbit choroid plexus epithelia. The goal of the current study was to determine the suitability of this primary cell culture for the study of the Na+-taurine transporter in the rabbit choroid plexus. Methods. A primary cell culture of rabbit choroid plexus epithelial cells was grown on semi-permeable filters and kinetics of H-3-taurine uptake were ascertained. Results. Taurine transport in the cultured choroid plexus cells was Na+-dependent and saturable (K-m = 156 mu M). The beta-amino acids, beta-alanine and taurine, significantly inhibited Na+-driven taurine transport whereas L-alanine partially inhibited taurine transport in the cultured cells. In addition, we observed that the activity of the Na+-taurine transporter is affected by exposure to taurine in the media. Conclusions. These results demonstrate that a Na+-taurine transporter with characteristics similar to those in the intact tissue is expressed in cultured choroid plexus epithelial cells. The transporter may undergo adaptive regulation and play a role in taurine homeostasis in the central nervous system.