Inhibition of aspartate release from the retina of the anaesthetised rabbit by stimulation with light flashes.

Rabbits were anaesthetised and the cornea, iris, lens and vitreous were removed from eyes to form an eye-cup which was filled with Krebs-bicarbonate Ringer. The medium in the eye-cup was replaced at 10-min intervals and the amino acids in each resulting sample were assayed. Exposure of the dark-adapted retina to flashes of light (3 Hz) did not alter the efflux of glutamate glutamine, alanine, glycine or GABA. The efflux of taurine and ACh was greatly increased by light flashes, but in contrast, the release of aspartate was reduced by more than 50%, a result consistent with the suggestion that aspartate may be a photoreceptor transmitter substance.