Figure 3. Voltage dependence of inactivation and activation of Na_V1.7 and Na_V1.3 in Ins1 cells.

A, voltage dependence of inactivation (h _∞) of Na_V1.7 (black; n = 47) and Na_V1.3 (red; n = 34) when the α‐subunit is co­expressed with β₁‐ and β₂‐subunits in Ins1 cells. The curves represent a single Boltzmann fit to the data. Note slight deviation from inactivation at membrane potentials between −70 and −40 mV in Ins1 cells expressing Na_V1.7 (arrow). B, voltage dependence of Na_V1.7 (black; n = 39) and Na_V1.3 (red; n = 31) current activation (G/G _max) in Ins1 cells. The curves represent a single Boltzmann fit to the data. C, the black curve represents a model of β‐cell Na_V current inactivation behaviour composed of 15% Na_V1.3 and 85% Na_V1.7, fitted to a double Boltzmann function. Superimposed is a single Boltzmann fit to the model (dashed red). The β‐cell model exhibits a clear shoulder at conditioning membrane potentials of −70 to −40 mV (arrow). See also Table 1. [Color figure can be viewed at http://wileyonlinelibrary.com]