[Light adaptation properties of receptor potentials of cyprinid retina]

It was previously reported that changes in sensitivities of electroretinographic b-wave in the course of light adaptation depended on the intensity of background lights. B-wave sensitivity decreased with time by dimmer background lights, while it recovered during illumination with background lights of higher intensities. In this work we examined light adaptation properties of glutamate-isolated receptor potentials (P III components), using isolated and superfused cyprinid retinas. During dimmer background illumination, P III components were unchanged. When background lights were increased above certain levels, P III components showed partial recovery with time in the light. A detailed analysis of spectral sensitivities of P III components and their increment thresholds for several wavelengths indicated that the recovery of P III sensitivity appeared with background lights at which rod function was taken over by cone function. The results suggest that the recovery of b-wave sensitivity during brighter background illumination is partially a reflection of the adaptation property of cone photoreceptors.