A, in simultaneous pre- and postsynaptic whole-cell recordings, qEPSCs were recorded in the presence of TTX (1 μm), with the presynaptic pipette solution containing 10 mm or 100 mm l-glutamate at PT. After obtaining control qEPSCs, kynurenate (100 μm) was bath-applied. Sample average traces (top) and amplitude histograms (bottom) of qEPSCs in the presence (Kyn, red) or absence (Control, black) of kynurenate (superimposed), with 10 mm (left) or 100 mm (right) l-glutamate in the presynaptic pipette solution. The total number of events is 362 for each with 10 mm l-glutamate and 455 for each with 100 mm l-glutamate. B, the percentage of qEPSC inhibition by kynurenate with 10 mm (10 Glu, n= 5) and 100 mm (100 Glu, n= 7) l-glutamate in the nerve terminals. No significant difference was observed (N.S., P > 0.4). C, similar c.v.s of the qEPSC amplitudes in the presence of l-glutamate loaded at 1–100 mm, or without presynaptic whole-cell recording (Control), at PT (left) and RT (right).