Effects of 2-amino-4-phosphonobutyric acid (APB) and glycine on the oscillatory potentials of the rat electroretinogram.

Oscillatory potentials of the electroretinogram were monitored in dark-adapted rats following intravitreal injection of 2-amino-4-phosphonobutyric acid (APB), a glutamate analog that preferentially blocks the light response of depolarizing bipolar cells, or glycine, a known endogenous inhibitory neurotransmitter that suppresses the light response of cells in the inner retina postsynaptic to glycinergic neurons. Oscillatory potentials were abolished in conjunction with the b-wave with APB and selectively reduced or eliminated by glycine: neither agent attenuated the a-wave. The results are compatible with the idea that light-induced depolarizing bipolar cell, hyperpolarizing bipolar cell, and glycinergic amacrine cell responses are all necessary for the generation of oscillatory potentials in the rat. The results also suggest that hyperpolarizing bipolar cells do not contribute to b-wave generation.