Table.

Values of the Parameters Describing The Kinetics of All-trans Retinol Formation in Human Rod Photoreceptors Isolated From Different Donors

Donor Age (y)	11-cis Retinal	Cells, n	f1 (min–1)	f2 (min–1)	A
Ungenerated
90	—	6	0.50 ± 0.05	0.013 ± 0.001	47 ± 1
80	—	4	0.53 ± 0.10	0.022 ± 0.003	19 ± 1
80	—	7	0.25 ± 0.02	0.017 ± 0.001	91 ± 3
Regenerated
21	5 µM	9	0.26 ± 0.04	0.008 ± 0.001	99 ± 5
78	5 µM	4	0.44 ± 0.05	0.012 ± 0.001	65 ± 2
	2.5 µM	4	0.55 ± 0.09	0.013 ± 0.001	28 ± 1
88	5 µM	5	0.24 ± 0.05	0.013 ± 0.003	50 ± 4
	2.5 µM	5	0.33 ± 0.09	0.002 ± 0.003	77 ± 7

For three of the donors, cells were not regenerated with 11-cis retinal prior to the measurement of all-trans retinol formation (unregenerated). For another three donors, cells were regenerated by incubating for 10 minutes with 2.5- or 5-µM 11-cis retinal (regenerated). All experiments were conducted at 37°C. The parameters are as follows: f₁, rate constant for retinol formation; f₂, rate constant for retinol removal; and A, fluorescence corresponding to the amount of rhodopsin present before bleaching. Parameters were determined from least-square fits of Equation 2 to the experimental data points (as in Figs. 2B, 3B).