Intracellular Responses to Light from Cat Pigment Epithelium: Origin of the Electroretinogram c-Wave

Retinal degeneration is delayed by tissue factor pathway inhibitor-2 in RCS rats and a sodium-iodate-induced model in rabbits

“…21,24,25 SI degenerates the RPE and breaks down the integrity of the apical RPE cell membrane, leading to diminish or decrease the amplitude of the c-wave 21,23 immediately after SI is injected. Subsequently, the RPE regenerates and the integrity of the RPE is recovered 1-2 weeks after the injection of SI.…”

Potassium and the photoreceptor-dependent pigment epithelial hyperpolarization.

“…Most apparent were the fast retinal potentials (b-and d-waves) which added directly to the membrane hyperpolarization. This type of contamination was seen previously in pigment epithelial cell recordings in the cat, where a prominent b-wave was superimposed upon the apical membrane response (Steinberg et al 1970). The method used to synthesize the apical membrane potential (Fig.…”

“…Intracellular recordings from cat pigment epithelial cells in vivo have shown that the apical membrane (the membrane facing the photoreceptors) responds to a light stimulus with a slow hyperpolarization, whose time course is the same as that of the c-wave (Steinberg et al, 1970). This hyperpolarization is dependent upon the absorption of light by the photoreceptors since it has the rod action spectrum (Steinberg et al, 1970) and cannot be measured from the isolated pigment epithelium (Brown and Crawford, 1967). It has been suggested that this hyperpolarization is caused by a light-evoked change in the extracellular concentration of an ion (Noell, 1954(Noell, , 1963Steinberg et al, 1970;Steinberg and Miller, 1973).…”

“…This hyperpolarization is dependent upon the absorption of light by the photoreceptors since it has the rod action spectrum (Steinberg et al, 1970) and cannot be measured from the isolated pigment epithelium (Brown and Crawford, 1967). It has been suggested that this hyperpolarization is caused by a light-evoked change in the extracellular concentration of an ion (Noell, 1954(Noell, , 1963Steinberg et al, 1970;Steinberg and Miller, 1973). It is very likely that this ion is potassium since, in the frog, the apical membrane of the pigment epithelium has a high relative potassium conductance (Miller and Steinberg, 1977) and there is a light-evoked decrease in extracellular potassium ion concentration [K+]0 at the retinal side of the pigment epithelium, with a time course similar to that of the c-wave (Oakley and Green, 1976).…”

“…The c-wave of the electroretinogram (ERG) is believed to be generated primarily by the pigment epithelium (Noell, 1954(Noell, , 1963Brown and Wiesel, 1961;Steinberg et al, 1970), which is a single layer of epithelial cells located between the neural retina and the choroid. Intracellular recordings from cat pigment epithelial cells in vivo have shown that the apical membrane (the membrane facing the photoreceptors) responds to a light stimulus with a slow hyperpolarization, whose time course is the same as that of the c-wave (Steinberg et al, 1970).…”