Figure 6. Effect of DA (30 μM) on spontaneous miniature EPSCs (mEPSCs).

The mEPSCs were recorded in 7.5 mm external CaCl₂ Krebs solution containing TTX (0.3 μM), bicuculline (20 μM), strychnine (0.5 μM) and D-AP5 (25 μM). The holding potential was −60 mV. A, consecutive traces taken in control, 2 min after application of CNQX (5 μM), and after 15 min washout of CNQX. The mEPSCs were reversibly abolished by 5 μM CNQX. B, consecutive traces were taken in control and 3 min after application of 30 μM DA. The amplitude histograms were derived from 5 min stretches in control and 2–7 min after the onset of DA application. These histograms show the reduction in the number of events from 180 in control to 61 after application of DA. The inset traces in the histograms are the averaged traces of 180 events in control and 61 events during application of DA, respectively. The mean amplitudes of mEPSCs in control and in the presence of DA were 20.9 and 20.9 pA, respectively.