Fig. 4.

Stimulus response families (A) for Rpe65+/+ and Rpe65−/− mice supplemented with 2.5, 1.25, 0.25, and 0 mg of 9-cis-retinal. Each panel is the mean family for five rods of each type. Flash (10 ms) strengths increased in two-fold steps from the dimmest intensity that was (in equivalent 500 nm photons/μm²): Rpe65+/+ (3.12), 2. 50 (10.14), 1.25 (190), 0.25 (192), and 0 (1425) mg of 9-cis-retinal. As determined by HPLC retinoid analysis, 300 ± 25 pmol iso-Rh/eye was formed with 2.5 mg, 109.8 pmol of iso-Rh/eye with 1.25 mg and 85.6 ± 6.2 pmol/eye with a 0.25-mg dose of 9-cis-retinal. B, mean light-sensitive dark current for the same sets of rods in A. The error bars are smaller than the symbols. C, mean linear range responses for same cells in A are scaled to the same peak amplitude and superimposed to illustrate differences in response kinetics.