Figure 5.

Effect of Ca²⁺ omission or glutamate transporter block on the release of glutamate from rat hippocampal synaptosomes. Synaptosomes were exposed in superfusion to a 90s pulse of 25 mm KCl or 1 μm ionomycin, and the stimulus-evoked overflow of endogenous glutamate was measured. The stimulus-evoked overflow was calculated by subtracting the neurotransmitter content in the basal outflow from the release evoked by stimulation (see the legend to Fig. 1). dl-TBOA (100 μm) was introduced 9 min before KCl. Ca²⁺ was omitted 19 min before KCl. Data represent the means ± SEM of three to four separate experiments run in triplicate. ^*p < 0.001 versus the overflow induced by KCl or ionomycin in the absence of drugs (two-tailed Student's t test). Open bars, Controls; gray bars, Ca²⁺-free; filled bars, 100 μm dl-TBOA.