Vitamin-A Content of the Frog Eye during Light and Dark Adaptation

Abstract

Rhodopsin is synthesized from 11- cis retinene (vitamin A aldehyde), but releases all- trans retinene when bleached by light. In the frog, both isomers of vitamin A are stored in the eye. Total ocular vitamin A, including that bound as retinene in rhodopsin, remains constant during light and dark adaptation. Stores of 11- cis vitamin A, however, diminish in the light and are replenished in darkness.