CaM-induced shift of inactivation in hNa_V1.4 channels.

Representative Na⁺ currents and I–V relationships for wild type (A) and hNa_V1.4_F1705I channels (B) elicited by the same pulse protocol shown in the inset of Figure 1B. CaM and CaM₁₂₃₄ over expression significantly (p<0.05) shifts the wild type but not the hNa_V1.4_F1705I I–V in the depolarizing direction. (C) Representative steady-state inactivation currents elicited from different holding potentials. (D, E) Plots of the steady-state inactivation and activation relationships of wild type hNa_V1.4 (D) and hNa_V1.4_F1705I channels (E). The solid lines are the fits to steady-state inactivation data with CaM and CaM₁₂₃₄ over expression. There is a significant (p<0.005) depolarizing shift of the inactivation curve by CaM and CaM₁₂₃₄ compared to the expression of hNa_V1.4_F1705I alone. The symbols and colors are the same in all panels of the figure.