Figure 1.

IGF-I increases the cyclic nucleotide sensitivity of rod CNG channels. (A) CNG currents activated by application of 8-Br-cGMP (1, 2.5, 10, 25, and 250 μM) in excised patches from rods exposed to control or 1 μM IGF-I-containing saline for 10 min before patch excision. (B) Dose–response curves of CNG channel activation from control (n = 56) and IGF-I-treated (n = 10) rods. Continuous curves show fits to the Hill equation (mean K_1/2 values = 8.0 and 3.9 μM and Hill coefficients = 1.90 and 1.93, respectively). (C) Effects of 10-min pretreatment with 1 nM to 100 μM IGF-I (n = 7–25) and 100 nM of IGF-II, insulin, acidic fibroblast growth factor, and basic fibroblast growth factor (n = 5–11).