Characteristics of [3H]L-Glu transport at the blood-cerebrospinal fluid barrier. Isolated rat choroid plexus was incubated at 37°C with [3H]L-Glu (74 nM) and [14C]n-butanol (100 μM), which was used to determine the cell volume of the choroid plexus. A. Time-course of [3H]L-Glu uptake by isolated rat choroid plexus. Each point represents the mean ± SEM (n = 3-4). B. Effect of compounds on [3H]L-Glu uptake by isolated rat choroid plexus. Choroid plexus was incubated with [3H]L-Glu for 5 min in the absence (control) or presence of unlabeled L-Glu (1 mM), D-Asp (1 mM), kainate (0.5 mM), or L-cystine (0.25 mM). Each column represents the mean ± SEM (n = 3-4). *p < 0.05, **p < 0.01, significantly different from the control.