• Biomolecules & Therapeutics
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• v.17 no.2
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• pp.175-180
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• 2009

Taurine is the most abundant free amino acid in the retina and transported into retina via taurine transporter (TauT) at the inner blood-retinal barrier (iBRB). In the present study, we investigated whether the taurine transport at the iBRB is regulated by oxidative stress or disease-like state in a conditionally immortalized rat retinal capillary endothelial cell line (TR-iBRB) used as an in vitro model of iBRB. First, [$^3H$]taurine uptake and efflux by TR-iBRB were regulated in the presence of extracellular $Ca^{2+}$. [$^3H$]Taurine uptake was inhibited and efflux was enhanced under $Ca^{2+}$ free condition in the cells. In addition, oxidative stress inducing agents such as tumor necrosis factor-$\alpha$ (TNF-$\alpha$), lipopolysaccharide (LPS), diethyl maleate (DEM) and glutamate increased [$^3H$]taurine uptake and decreased [$^3H$]taurine efflux in TR-iBRB cells. Whereas, 3-morpholinosydnonimine (SIN-1), which is known to NO donor decreased [$^3H$]taurine uptake. Lastly, TR-iBRB cells exposed to high glucose (25 mM) medium and the [$^3H$]taurine uptake was reduced about 20% at the condition. Also, [$^3H$]taurine uptake was decreased by cytochalasin B, which is known to glucose transport inhibitor. In conclusion, taurine transport in TR-iBRB cells is regulated diversely at extracellular $Ca^{2+}$, oxidative stress and hyperglycemic condition. It suggested that taurine would play a role as a retinal protector in diverse disease states.

• Biomolecules & Therapeutics
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• v.24 no.1
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• pp.94-98
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• 2016

The objective of the present study was to elucidate the effect of bisphosphonates, anti-osteoporosis agents, on glucose uptake in retinal capillary endothelial cells under normal and high glucose conditions. The change of glucose uptake by pre-treatment of bisphosphonates at the inner blood-retinal barrier (iBRB) was determined by measuring cellular uptake of $[^3H]3$-O-methyl glucose (3-OMG) using a conditionally immortalized rat retinal capillary endothelial cell line (TR-iBRB cells) under normal and high glucose conditions. $[^3H]3$-OMG uptake was inhibited by simultaneous treatment of unlabeled D-glucose and 3-OMG as well as glucose transport inhibitor, cytochalasin B. On the other hand, simultaneous treatment of alendronate or pamidronate had no significant inhibitory effect on $[^3H]3$-OMG uptake by TR-iBRB cells. Under high glucose condition of TR-iBRB cells, $[^3H]3$-OMG uptake was increased at 48 h. However, $[^3H]3$-OMG uptake was decreased significantly by pre-treatment of alendronate or pamidronate compared with the values for normal and high glucose conditions. Moreover, geranylgeraniol (GGOH), a mevalonate pathway intermediate, increased the uptake of $[^3H]3$-OMG reduced by bisphosphonates pre-treatment. But, pre-treatment of histamine did not show significant inhibition of $[^3H]3$-OMG uptake. The glucose uptake may be down regulated by inhibiting the mevalonate pathway with pre-treatment of bisphosphonates in TR-iBRB cells at high glucose condition.