Molecular underpinnings of rod in vivo kinetics. (A) Normalized population average in vivo flash family obtained via the paired flash protocol in response to test flashes calculated to produce 14, 70, 107, 285, 550, 2,150, 4,280, 8,770, 17,500, and 35,100 R*/rod. Symbols plot the mean ± SEM (n = 3–6 mice) and are connected by cubic splines. (B) Representative family of responses obtained from an intact rod using suction electrode recording in response to flashes producing 7, 14, 48, 174, 585, 997, 1,870, 3,300, 6,330, 13,400, and 25,100 R*/rod. (C) Response amplitudes plotted as a function of test flash strength for the data obtained in vivo (A, black) and ex vivo (B, gray); smooth curves are exponential saturation functions. (D) Dim flash responses from WT (n = 6), RGS9-ox (n = 4), and GCAPs^−/− (n = 4) mice, fitted by the phototransduction spatiotemporal model of Gross et al. (2012a) with parameters given in Table 1. All traces represent the response to a flash of the same light intensity and are normalized by the peak amplitude of the GCAPs^−/− response. The blue symbols present a normalized version of the response to the dimmest flash in A. Error bars represent SEM.