FIGURE 7.

S516E and T594E phosphomimetics shift I_Na availability independent of CaMKII. A, V₅₀ of activation was not different among phosphomimetics or compared with WT. B, T594E and S516E I_Na V₅₀ of availability was shifted to negative V_m in the presence of AIP and without δ_C-CaMKII co-expression (indicated by striping). V₅₀ of availability for S571E and S516E/T594E was not significantly different from WT with AIP (*, p < 0.05 by ANOVA versus WT with AIP; bracket indicates no difference by t test for S516E and T594E versus WT with δ_C-CaMKII). C, expanded version of B, for comparing the effect of AIP omission (versus with AIP) in the pipette for different Na_V1.5. For the T594E phosphomimetic, availability was not altered when endogenous CaMKII was allowed to function (versus with AIP). For S516E, endogenous CaMKII partly reversed the effect of the phosphomimetic. S571E, which did not mimic the CaMKII-induced shift in V₅₀ when AIP was present (in contrast to S516E and T594E) could still shift V₅₀ negative by endogenous CaMKII activity. (n as indicated, ±S.E. (error bars); AIP and exogenous CaMKII present only where indicated). #, p < 0.05 by t test versus with AIP for the same Na_V1.5 type.