Regeneration of rhodopsin in the isolated retina of the frog ( rana esculenta)

Abstract

Isolated retinae of the frog ( Rana esculenta) were exposed to quasimonochromatic radiation of 450, 475, 500 or 540 nm wavelength, respectively. These coloured lights were formed by a prism monochromator whose band-width was set to 12–16 nm. More than 90 per cent of rhodopsin was found to be in the bleached state after exposure times of 30–50 min. A fraction of the bleached pigment was regenerated during a subsequent dark period of 90 min. The fraction regenerated (7–24 per cent) was found to depend on the spectral content of the bleaching light in such a way that wavelengths shorter than 500 nm favoured the regeneration process. Regeneration occured from a substance with maximum absorption at 380 nm. This substance is assumed to be retinaldehyde in which the correct isomer for regeneration (11- cis) is formed via photoisomerization.