Effect of fenretinide on cone dark adaptation in isolated retina. (A–E) Representative families of ex vivo cone ERG responses from Gnat1−/− mouse retinas under specified conditions. (A and C) Test flashes of 505-nm light with intensities of 235, 705, 2.4 × 103, 7.0 × 103, 1.7 × 104, 5.7 × 104, 2.0 × 105, and 6.0 × 105 photons/µm2 were delivered at time 0. (B, D, and E) Test flashes of 505-nm light with intensities of 2.4 × 103, 7.0 × 103, 1.7 × 104, 5.7 × 104, 2.0 × 105, 6.0 × 105, 2.0 × 106, and 5.7 × 106 photons/µm2 were delivered at time 0. In all panels, responses to 1.7 × 104 photons/µm2 light are shown in red for comparison of cone sensitivity recovery after a bleach. (F) Averaged cone intensity–response functions (mean ± SEM) for dark-adapted conditions treated for 1 h with 1.3% DMSO (vehicle control, open circles; n = 6) or with 650 µM fenretinide (open red circles; n = 6) and 1 h after a bleach of retinas preincubated for 1 h in 1.3% DMSO (vehicle control, closed black circles; n = 11), 100 µM fenretinide (closed blue squares; n = 6), or 650 µM fenretinide (closed red circles; n = 9). The recovery of cone sensitivity was suppressed by treatment with fenretinide at both 100 µM and 650 µM.
