Figure 7.

Removal of exogenous all-trans-retinal and retinol from rod outer segments. bROS from Rpe65^−/− mice, containing negligible amounts of endogenous retinoids, were loaded with 50 μm retinal or retinol for 10 min, supplied with 1% BSA as carrier. Supply of exogenous retinoid was terminated at t = 0. Retinoid outer segment fluorescence intensities have been normalized over the value at t = 0. The lines are simple exponentials, e^−k·t, decaying to 0 with unitary amplitude at t = 0 min, and have been drawn with rate constants k determined from the experimental data points. A, removal of exogenous all-trans-retinal. In the absence of IRBP, retinal fluorescence declined with rate constant 0.007 ± 0.003 min⁻¹ (●, n = 9); in the presence of 5 μm IRBP, fluorescence decreased with rate constant 0.05 ± 0.01 min⁻¹ (○, n = 4). B, removal of exogenous all-trans-retinol. In the absence of IRBP, retinol fluorescence declined with rate constant 0.052 ± 0.005 min⁻¹ (▴, n = 8); in the presence of 5 μm IRBP, fluorescence decreased with rate constant 0.390 ± 0.002 min⁻¹ (▵, n = 5). Error bars represent standard deviations. The errors for the removal rate constants were obtained from the curve fits.