Off-pathway synaptic transmission in the outer retina of the axolotl is mediated by a kainic acid-preferring receptor

Intracellular recordings were made from OFF-centre bipolar cells and horizontal cells in the superfused axolotl retina eyecup preparation. Bath-applied (+/-)cis-2,3-piperidine dicarboxylic acid (PDA), gamma-D-glutamylglycine (DGG), L-glutamic acid diethyl ester (GDEE), (+/-)2-amino-5-phosphonovaleric acid (2-APV) and magnesium ions were assessed as antagonists of the actions of the photoreceptor transmitter. The rank order of antagonist efficacy was PDA greater than DGG greater than greater than 2-APV = GDEE = Mg2+. The results indicate that transmission at OFF-pathway synapses in the outer retina of the axolotl is mediated by a kainic acid-preferring receptor.