Fig. 6.

AMPA receptors of fast- and slow-rising EPSCs are activated by different glutamate concentrations. The effects are shown of 2 mM γ-DGG (gray) on fast-rising (A) and slow-rising (B) AMPAR EPSCs. C: plot of the percentage peak amplitude blocked by γ-DGG vs. the EPSC rise time (10–90% rise time, ms). The data are fit by an exponential equation (dashed line). D: summary graph of the average percent inhibition of the peak amplitude by γ-DGG (“fast” n = 6; “slow” n = 6). Ei: time course of peak slow-rising AMPAR EPSC before and in the presence of the glutamate transport blocker dl-threo-β-benzyloxyaspartic acid (TBOA; 10 μM) followed by the application of 50 μM GYKI52466. ii: Average EPSCs from the same experiment before (black line), during bath application of TBOA (gray line) and in the presence of TBOA+GYKI (dashed line). Traces are the average of 15–20 trials. F: summary graph of the effects of TBOA on the slow-rising EPSCs (n = 8), quantifying the average change in peak amplitude, rise time and normalized charge transfer. Q, synaptic charge. Individual experiments are shown as gray circles. All recordings were performed in the presence of (R)-CPP and d-AP5 to block NMDAR-mediated EPSCs and CTZ to prevent AMPAR desensitization. Bath temperature: 35 ± 1°C. *P < 0.05. ***P < 0.001.