Figure 4.

Different glutamate receptors mediate activation of glycinergic amacrine cells. A, Feedback IPSCs were reduced by the non-NMDAR antagonist NBQX (25 μm). B, Feedback IPSCs also were reduced by the NMDAR antagonist CPP (10 μm) and eliminated by coapplication with NBQX (25 μm). C, Feedback IPSCs were reduced by application of the AMPAR antagonist GYKI 53655 (50 μm); coapplication of CPP reduced the IPSC further, but a small component remained. D, The Ca²⁺-permeable AMPARs antagonist philanthotoxin did not reduce IPSCs, but CPP and NBQX eliminated them. E, Summarized drug effects (mean ± SD) on IPSCs. ND, Experiment not done. Experiments were performed in the presence of GABAR antagonists (SR95531 and TPMPA) and DHT. GYKI, GYKI 53655; PhTx, philanthotoxin.