Long-lived photoproducts of rhodopsin in the retina of the frog

We find that Baumann's (1972) model with appropriate values for the rate constants rather well describes the spectral changes observed after irradiation of frog retinas at varying temperatures (0–25°C) and pH-values (6·0–7·9). The rates of both reactions leading to retinal, i.e. the decay of metarhodopsin III and the direct conversion of metarhodopsin II into retinal, decrease with increasing pH, which explains the accumulation of large amounts of M III in slightly alkaline retinas