PolyP application significantly hyperpolarizes Na
channel activation. A) Holding at -86 mV, polyP application evokes current spikes. Upper panel: expanded time course of activity onset. Lower panel: complete time course for polyP evoked activity. B) Representative INaV traces recorded during a voltage step protocol (see Methods). Before polyP application, INaV activates at voltages positive to -55 mV. After polyP, INaV activates at voltages positive to -80 mV. All inward currents were blocked by TTX. C) Normalized data plotted as I/Imax versus voltage. Normalized and averaged data (see Methods) were fit with the Boltzmann equation before and after polyP: Vh = -32.5 & -54.3, Erev = 6.4 & 6.9, S = 7.8 & 8.9, G = 39.7 & 55.0, n = 5 & 5, respectively.