Figure 2

Expression of I234T tends to lower current threshold in DRG neurons that are excitable at native resting potential. (A) Scatter-plot of current threshold in neurons expressing either WT or I234T. Filled circles in magenta represent silent cells that did not fire in response to external stimuli from their native resting potentials but regain excitability when held at −60 mV. Their current thresholds at native potentials were considered infinite. (B) In neurons that were excitable at native resting potentials, I234T tended to reduce average current threshold, compared to WT. (C) Populations of cells with current thresholds ≤ 200 pA (orange), > 200 pA (green) and silent (magenta) at their native resting potentials. (D) Representative responses of neurons expressing WT or I234T to 200 ms current injections in 5 pA increments. The cell expressing WT had an RMP of −56 mV and a current threshold of 290 pA (upper). The neuron expressing I234T had an RMP of −55 mV and generated an action potential at a threshold of 190 pA (lower).