A, glycine (100 μM) was rapidly applied to a neurone under control conditions (a), after pretreatment with, and in the presence of 500 nM strychnine (b), and after pretreatment with, and in the presence of 500 nM strychnine and 50 μM OAG (c). B, in another neurone, glycine was applied alone (a), in the presence of 500 μM DCKA (b), and in the presence of both DCKA and 50 μM OAG. Neurones were clamped at 0 mV.