Abstract
1. The early receptor potential (early RP), which results from very intense photo-stimulation of the vertebrate eye, has been investigated in isolated pre-parations from the bullfrog's eye.All the preparations were placed as a septum separating the solutions in the apparatus.
2. The early RP of the retina with the pigment epithelium intact was more resistant to light adaptation than that of the retina alone, and its ampli-tude declined much more readily in the anaerobic than in the oxygenated condition. This clearly suggests that the pigment epithelium is necessary for the fast and sufficient regeneration of the visual pigments and that it requires oxygen to attain maximal activities.
3. Increasing the potassium concentration on both sides or the scleral side of the retina alone, the amplitude of the early RP was enhanced and the ratio of heights of positive and negative phases was decreased, whereas on the vitreous side the amplitude was increased, but the ratio remained unchanged. On the basis of these results it is proposed that an enhancement of the re-sponse is due to an increase of the transretinal electrical conductivity and a decrease in amplitude of a depolarizing potential which is probably elicited from the cell membrane of outer segments.
4. The early RP of retinal photoreceptors was not affected by a dc current across the retina, but the pigment epithelium-choroid complex generated a new slow response by an intense light flash under polarized condition.
