Suitability of retinol, retinal and retinyl palmitate for the regeneration of bleached rhodopsin in the isolated frog retina

The all-trans, 9-cis and 11-cis isomers of retinol, retinal and retinyl palmitate were incorporated into unilamellar dioleoyl-lecithin vesicles (liposomes). Isolated frog retinas were inserted into a perfusion chamber and their absorption spectra were recorded (i) in the dark-adapted state, (ii) after exposure to intense light that bleached greater than 95% of rhodopsin and (iii) after liposomes had been added to the perfusate of the bleached preparations. In each experiment, one of the above isomers of the retinol analogs was tested. Regeneration was promoted by the 9-cis and the 11-cis isomer of retinol and of retinal whereas the trans isomers of all compounds and the cis isomers of retinyl palmitate were inactive.