Fig. 4.

Decay phases of I_NaT and I_NaR. In the panel on the left, Nav current waveforms recorded from an isolated neonatal Purkinje neuron during two different voltage-clamp paradigms are shown; the voltage-clamp paradigms are illustrated above the current records. In the first case, membrane depolarization to − 40 mV from a holding potential (HP) of − 90 mV (red) evoked I_NaT (red); note the fast (red, open arrow) and slow (red, filled arrow) components of inactivation of I_NaT. Membrane repolarization to − 40 mV following a brief (5 ms) strong (+ 10 mV) depolarization from the same HP revealed I_NaR (black). Note that the time course of I_NaR decay (black, filled arrow) and the slow component of I_NaT inactivation (red, filled arrow) are indistinguishable. The currents are shown on expanded amplitude and time scales in the records shown in the panel on the right