Comparison of mean response waveform of GAPux, GAPux;RKS561L, and GAPux;Rv−/− rods to 20-ms flashes given at t = 0 for each rod type at the same intensities (in photons µm⁻²): 3, 9, 23, 75, 130, 240, 430, 780, 1,500, and 2,800. Horizontal lines show value of current at 25% of maximum used in estimating values of Tsat in Fig. 5. (A) GAPux, mean of 16 rods. (B) GAPux;RKS561L, mean of 20 rods. (C) GAPux;Rv−/−, mean of 10 rods. Not all of the rods in Table 1 were used for this figure because responses at every flash intensity were not recorded from every rod. Red traces are responses for each rod type to flashes of 23 photons µm⁻². Note that averaging of rod responses tends to slur the decay phases of individual photoreceptors, which vary from rod to rod, with the result that the averaged response especially at bright intensities is not representative of any one individual cell. Mean decay times averaged cell by cell are given in Figs. 4 B and 5.