PURPOSE This study tested the hypothesis that the function of the glutamate transporter in retinal Müller cells is compromised early in the course of diabetes by a mechanism involving oxidation. Dysfunction of this transporter, which removes glutamate from the extracellular space, may play a critical role in the disruption of glutamate homeostasis that occurs in the diabetic retina. Because glu...

Dihydrokainate, a glutamate transporter inhibitor, was previously found to be a useful modulator of antitumor activity of doxorubicin (DOX). Dihydrokainate prevented an efflux of DOX by inhibiting the uptake of glutamate by tumor cells. We examined the potential of glutamate transporter inhibitors as modulators of DOX activity. We observed a significant reduction in the uptake of glutamate by o...

General anesthesia impairs glutamate homeostasis at synapses by decreasing the production of glutamate transporters. Glutamate transporters in astrocytes are important to preserve cognitive function and memory in hippocampus. In this study we investigated whether ulinastatin increases the number of glutamate transporters in glial cells. We used human astrocytes to demonstrate glutamate uptake i...

The effects of gamma-aminobutyric acid (GABA) on the release of glutamate from mouse spinal cord nerve endings have been studied using superfused synaptosomes. GABA elicited a concentration-dependent release of [3H]D-aspartate ([3H]D-ASP; EC50= 3.76 microM). Neither muscimol nor (-)baclofen mimicked GABA, excluding receptor involvement. The GABA-evoked release was strictly Na+ dependent and was...

We evaluated the role of the sodium/glutamate transporter at the synaptic terminals of cone photoreceptors in controlling postsynaptic response kinetics. The strategy was to measure the changes in horizontal cell response rate induced by blocking transporter uptake in cones with dihydrokainate (DHK). DHK was chosen as the uptake blocker because, as we show through autoradiographic uptake measur...

A rise of brain ammonia level, as occurs in liver failure, initially increases glutamate accumulation in neurons and glial cells. We investigated the effect of acute exposure to ammonia on glutamate transporter currents in whole cell clamped glial cells from the salamander retina. Ammonia potentiated the current evoked by a saturating concentration of L-glutamate, and decreased the apparent aff...

Human erythrocytes have a low basal permeability to L-glutamate and are not known to have a functional glutamate transporter. Here, treatment of human erythrocytes with arsenite was shown to induce the uptake of L-glutamate and D-aspartate, but not that of D-glutamate or L-alanine. The majority of the arsenite-induced L-glutamate influx was via a high-affinity, Na(+)-dependent system showing ch...

Human erythrocytes have a low basal permeability to L-glutamate and are not known to have a functional glutamate transporter. Here, treatment of human erythrocytes with arsenite was shown to induce the uptake of L-glutamate and D-aspartate, but not that of D-glutamate or L-alanine. The majority of the arseniteinduced L-glutamate influx was via a highaffinity, Na -dependent system showing charac...

The present study established a rat model of global cerebral ischemia induced by chest compression for six minutes to dynamically observe expressional changes of three glutamate transporters in the cerebral cortex and hippocampus. After 24 hours of ischemia, expression of glutamate transporter-1 significantly decreased in the cerebral cortex and hippocampus, which was accompanied by neuronal ne...