Figure 5. Sensitivity of rod bipolar cell responses to their rod input increases in P23H/Gnat2^-/- mice.

Ex vivo ERG rod (A) and RBC (B) response amplitudes, and their ratio (C) derived as in Figure 4. (D–F) RBC plotted as a function of R_PR in individual retinas from Gnat2^-/- control (D), and one month (E) and five month (F) P23H/Gnat2^-/- mice. Smooth lines in A and B plot Equation 1 fitted to mean data. Smooth lines in D-F plot Equation 2 fitted to data from individual retinas. *p<0.05, **p<0.005, ***p<0.001, ****p<0.0001. Statistics for R_max and intensity required to generate half-maximal rod or RBC response (I_1/2) as well as R_PR,1/2 are in Table 1. In C, two-way ANOVA followed by Bonferroni’s post hoc test was used to compare between-subjects main effect and the intensity where a significant effect was found, respectively. (Pooled control, 1–6 mo, n = 7 (11); P23H, one mo, n = 4 (6); five mo, n = 11(18); six mo, n = 2 (4) mice(retinas)).

Figure 5—figure supplement 1. Contribution of Müller cell response on the ex vivo ERG light responses in control and P23H mice.

Light responses to identical flash of light in the absence of BaCl₂ (A), in the presence of 100 μM BaCl₂ (B) and Müller cell response (slow PIII) derived by subtracting the response in B from that shown in A (C). Mean (± SEM) b-wave amplitudes as a function of light flash intensity in the absence (D) and presence (E) of BaCl₂ in 1-month-old control Gnat2^-/- (black) and P23H/Gnat2^-/- (red) mice. (F) Slow P-III amplitudes plotted as a function of light flash intensity in control and P23H mice. (Control, n = 5 (8); P23H, n = 8 (12) mice(retinas)). No differences between control and P23H mouse means in D and E. A statistically significant group-stimulus intensity interaction was found in F (p<0.01); however, post-hoc test did not reach statistical criterion at any light intensity. Statistical analysis was performed by repeated measures two-way ANOVA followed by Bonferroni’s post hoc test.