A, in the presence of intracellular lavendustin A (10 μm), the mean NMDA current (±s.e.m.), compared to the second NMDA response in the presence of SKF-82958 and spiperone (n= 14, P > 0.05). B, in the presence of intracellular PP2 (10 μm), the mean NMDA current (±s.e.m.) compared to the second response in the presence of SKF-82958 and spiperone (n= 9, P > 0.05).