Evidence in support of a photoreceptoral origin for the "light-peak substance".
The light peak of the DC ERG was recorded in in vitro preparations of chick neural retina-RPE-choroid. Either the pharmacological agents Co2+, Mg2+, and low Ca2+, known to block calcium-dependent synaptic transmission or 2-amino-4-phosphonobutyric acid (APB), which blocks transmission in the ON pathway, were added to the solution perfusing the retina. These agents suppressed the b-wave of the ERG, thus indicating a severe suppression of synaptic transmission in the neural retina. The retina was also perfused with the OFF pathway inhibitor cis-2,3-piperidine dicarboxylic acid (PDA). None of these agents, however, significantly depressed the light peak, supporting the hypothesis that the light peak is generated by a photoreceptor-RPE interaction.
Gallemore
R P
RP
Department of Physiology, University of California, San Francisco 94143-0444.
Griff
E R
ER
Steinberg
R H
RH
D000818:Animals; D002829:Choroid / Q000502:physiology; D004596:Electroretinography; D008027:Light; D009433:Neural Inhibition; D010786:Photoreceptor Cells / Q000502:physiology*; D010857:Pigment Epithelium of Eye / Q000502:physiology; D012016:Reference Values; D012160:Retina / Q000502:physiology; D013569:Synapses / Q000502:physiology; D009435:Synaptic Transmission