Figure 6.

Effects of coexpressing β₁ subunits on the steady-state inactivation and EPA-induced inhibition of Na⁺ currents in HEK293t cells expressing N406K or plus the β₁ subunit. (A) Concentration-dependent inhibition of Na⁺ currents by EPA in HEK293t cells transfected with N406K alone (N406K) or cotransfected with N406K and β₁ subunits (N406K + β₁). Each bar represents the average value of at least seven individual cells. *, P < 0.05; **, P < 0.01; versus control. #, P < 0.05; N406K plus β₁ versus N406K. (B) The effects of coexpressing β₁ subunits on the steady-state inactivation of I_Na in the absence or presence of 5 μM EPA for N406K and N406K plus β₁. Currents were elicited by 10-ms test pulses to 30 mV following 500-ms conditional prepulses varying from −160 mV to −20 mV with 10-mV increments. The membrane holding potential was −150 mV, and the pulse rate was 0.1 Hz. The dotted line and dashed-dotted line correspondingly represent in the absence and presence of 5 μM EPA for the steady-state inactivation of the wild type of hH1_α Na⁺ channels. The data were fit with a Boltzmann equation.