Figure 5.

Recoverin accounts for half of the desensitization caused by low Ca²⁺ exposure in GCAP^−/− mouse rods and most changes in flash response kinetics. (A) Dim-flash responses (<20% of saturated response amplitude) normalized with the saturated response amplitude, and flash energy (in R* per rod) for GCAP^−/− (n = 4) in normal (black) and low (red) Ca²⁺ solution, and for DKO (n = 3) mouse retinas in normal (blue) and low (magenta) Ca²⁺ solution. Inset shows the same responses normalized to their peak amplitudes. All data in A are mean ± SEM (B and C). Representative near-saturated and saturated responses recorded from dark-adapted GCAP^−/− mouse retinas in normal (B; flash strength range: 990–6,300 R* per rod) and low (C; flash strength range: 630–4,000 R* per rod) Ca²⁺ solution. (D) Saturation times at 25% recovery as a function of flash strength in normal (black) and low (red) Ca²⁺ conditions from GCAP^−/− (squares; n = 4) and in normal (blue) and low (magenta) Ca²⁺ conditions from DKO (circles; n = 4) mouse rod responses (mean ± SEM). The slopes of the fitted lines, τ_D, were 234 and 203 ms in normal [Ca²⁺] and 185 and 185 ms in low [Ca²⁺] for GCAP^−/− and DKO mice, respectively. Error bars represent ± SEM.