Cortico-RT synaptic release is suppressed to a similar extent by separate applications of 20 or 300 μm l-AP4. A, B, Peak amplitude of paired-pulse EPSCs evoked by optical stimulation for experiments in which either 20 μm l-AP4 (A, n = 3) or 300 μm l-AP4 (B, n = 4) was applied. Amplitudes are normalized to mean baseline amplitude of first EPSC. Washout epoch: min 15–45. C, Normalized first EPSC amplitude during late baseline epoch and first drug wash-in epoch pooled from experiments in which either l-AP4 20 μm (n = 8) or l-AP4 300 μm (n = 6) were applied. EPSC amplitudes are normalized to mean baseline amplitude. There was a significant main effect of epoch (F_(1,12) = 61.40, ***p < 0.001, two-way rANOVA), but no significant interaction of epoch and drug concentration (F_(1,12) = 0.13, p > 0.05). D, PPR of EPSC amplitude was not affected by l-AP4. There was no main effect of epoch (F_(1,12) = 1.05, p > 0.05, two-way rANOVA) or interaction of epoch and drug concentration group (F_(1,12) = 0.04, p > 0.05). Bar graphs show mean amplitudes of the last 2 min of each epoch.