Tracing of benzidine-reactive substances in ROS, RPE and choroid after light-induced peroxidation

Abstract

Light conditions that trigger the disc shedding possibly activate a mechanism to extrude peroxidative damaged material over the complete ROS into the extracellular space to diminish peroxidative damage inside the ROS. Indigestible residual material from the ROS degradation in the phagosomes consists of membranous lipids associated with peroxidative damaged proteins. The residual material seems to be transported through Bruch's membrane into the choriocapillaris.

Cellular transport of subretinal material into choroidal and scleral blood vessels: an electron microscopic study

“…Indigestible material inside the RPE is thought to be removed by exocytosis into the basal labyrinth, followed by extracellular diffusion through Bruch's membrane to be taken away by choroidal veins [9,11,13,21]. The present study describes a second, cellular mechanism for the removal of residual material from the RPE to choroidal and scleral vessels by ED 1-positive wandering cells.…”

“…Additionally, our investigation shows clearly that the material concerned (MB) is subsequently taken up by RPE cells. The fact that after an additional incubation time no indigestible MB is seen in the RPE implies transportation of the dye from the RPE cell layer, either by phagocytic cells or by an excretion of the indigestible material into the extracellular space, as proposed by others [9,11,13,21]. The detection of MB-and melanincontaining cells in the choroid and sclera of the injected eyes points to the existence of wandering cells containing the indigestible material.…”

“…shed tips of photoreceptor outer segments which are endocytized from the subretinal space by RPE cells and digested by their lysosomes [2,28,29]. If indigestible material is left over, it is believed to be exocytized by the basal surface of the RPE cell and to cross through Bruch's membrane to be finally removed by the blood vessels of the choroid [9,11,13,21]. However, with increasing age lysosomes in the RPE cells become less effective.…”

Light‐induced Damage to the Retina: Role of Rhodopsin Chromophore Revisited

“…The oxygen tension in the arteries can be further elevated due to oxygen supplementation during ocular surgery (84). Involvement of photodynamic effect in retinal photodamage is further supported by the findings that retinal photodamage is accompanied by lipid peroxidation (85,86), suggesting that it is mediated by reactive oxygen species. As nitric oxide is inherently produced in the retina, it is not surprising that nitrogen reactive species are also formed and lead to the nitration of retinal proteins (87).…”