Involvement of TauT/SLC6A6 in Taurine Transport at the Blood-Testis Barrier.

Taurine transport was investigated at the blood-testis barrier (BTB) formed by Sertoli cells. An integration plot analysis of mice showed the apparent influx permeability clearance of [H]taurine (27.7 μL/(min·g testis)), which was much higher than that of a non-permeable paracellular marker, suggesting blood-to-testis transport of taurine, which may involve a facilitative taurine transport system at the BTB.

Involvement of sodium-coupled neutral amino acid transporters (system A) in l-proline transport in the rat retinal pericytes.

The retinal pericytes contribute to the supply of collagen to the basement membrane, and thus, form the structural support of the blood-retinal barrier. Since l-proline (L-Pro) is a major component of collagen, the uptake of L-Pro is an important process for the synthesis of collagen. This study was aimed to elucidate L-Pro transport mechanism(s) in the retinal pericytes.

Function and regulation of taurine transport in Müller cells under osmotic stress.

In the retina, taurine works as an osmolyte to exert a neuroprotective function, and it has been proposed that Müller cells, a major type of retinal glial cells, are involved in the osmolarity regulation of retinal neural cells by controlling the taurine concentration in retinal extracellular fluid (ECF). However, the detailed mechanism of taurine transport in Müller cells has not fully examined, and we investigated this using a conditionally immortalized rat Müller cell line (TR-MUL5 cells). In the uptake study, TR-MUL5 cells exhibited Na(+)-, Cl(-)-dependent [(3)H]taurine uptake with a K(m) of 37.

Inner blood-retinal barrier mediates l-isomer-predominant transport of serine.

D-serine, a coagonist for N-methyl-D-aspartate-type glutamate receptors, which mediate visual signal transmission, is thought to be generated from L-serine via serine racemase in the retina. However, the source of L-serine and D-serine in the retina are yet to be determined. The purpose of the present study was to investigate the characteristics of the blood-to-retina transport of serine at the inner blood-retinal barrier (BRB).

Involvement of system A in the retina-to-blood transport of l-proline across the inner blood-retinal barrier.

The purpose of the present study was to elucidate the mechanisms of retina-to-blood transport of l-proline across the blood-retinal barrier (BRB) in vivo and in vitro, and to identify the responsible transporter(s). The vitreous humor/retina-to-blood transport of [(3)H]l-proline across the BRB was evaluated by microdialysis. Transport mechanisms of [(3)H]l-proline were investigated by cellular uptake using an in vitro model of the inner BRB (TR-iBRB2 cells).

Roles of inner blood-retinal barrier organic anion transporter 3 in the vitreous/retina-to-blood efflux transport of p-aminohippuric acid, benzylpenicillin, and 6-mercaptopurine.

The purpose of the present study was to characterize rat organic anion transporter (Oat) 3 (Oat3, Slc22a8) in the efflux transport at the inner blood-retinal barrier (BRB). Reverse transcription-polymerase chain reaction analysis showed that rat (r) Oat3 mRNA is expressed in retinal vascular endothelial cells (RVECs), but not rOat1 and rOat2 mRNA. The expression of Oat3 in the retina and human cultured retinal endothelial cells was further confirmed by Western blot analysis.