Regeneration of Porphyropsin in vivo

Abstract

SCOTOPIC vision is mediated by the rod cells of the retina which contain a photosensitive pigment that (according to species) can be rhodopsin, porphyropsin, or a mixture of both. The pigment content may be diminished by exposure to light, but there is no permanent loss because the light-decomposed molecules are restored by regeneration. Although the time course and some details of the mechanism of rhodopsin regeneration in vivo are well known¹, we have little and contradictory information about the regeneration of porphyropsin. According to Kühne and Sewall² and Abelsdorff³, the por-phyropsin-like pigment in the retina of the living bream (Abramis brama)^4,5 is regenerated within 30–40 min. Garten⁶, however, who worked with the same fish, found regeneration to be complete after not less than 4 h. I have found a similar figure for regeneration of porphyropsin in the retina of crucian carp (Carassius carassius).