Effect of NR2A and NR2B antagonists on synaptic NMDA receptors. A, Representative traces show the inhibiting effects of EAB-318 (200 nM), ifenprodil (3 μM) and CPP (200 nM) on NMDA EPSCs evoked by focal stimulation and recorded from 3 EGFP+ neurons. Cells were held at +50 mV while EPSCs were recorded. B, shows the summary of NMDA receptor pharmacology recorded from EGFP+ and EGFP- neurons. The percentages of inhibition by EAB318, ifenprodil, and CPP on synaptic NMDA EPSCs were not significantly different between EGFP+ and EGFP- neurons (ns; not significant). We were able to obtain washout data on several of these neurons. The washout of antagonists ranged from 25% to 100% recovery of the blocked portion of the original NMDA EPSC amplitude. For the EGFP+ neurons, we were able to hold the neuron under study long enough to show washout in 6/16 neurons exposed to EAB318, 2/11 to CPP and 1/8 to ifenprodil. For the EGFP- neurons, we recorded partial to full recovery from 5/20 neurons exposed to EAB318, 2/14 neurons exposed to CPP and 2/8 neurons exposed to ifenprodil.