Skip to main content
. 2019 Sep 3;13:918. doi: 10.3389/fnins.2019.00918

FIGURE 3.

FIGURE 3

N816K mutation depolarizes resting membrane and reduces threshold for action potentials in small DRG neurons. (A) A representative 30 s trace from a cell expressing N816K mutant channels demonstrates spontaneous firing of action potentials (left panel). However, N816K mutant channels do not change the proportion of spontaneously-firing cells, compared to WT hNav1.9 channels (right panel). (B) Scatter plot of resting membrane potential (RMP) in small DRG neurons expressing WT or N816K mutant hNav1.9 channels. Solid lines indicate mean RMP. ∗∗∗p < 0.001. (C) Scatter plot of current threshold, the minimal current injection required to elicit an action potential in small DRG neurons expressing WT or N816K mutant hNav1.9 channels. Solid lines indicate mean RMP. ∗∗∗p < 0.001. (D) Representative action potential traces recorded from a small DRG neuron expressing WT hNav1.9 channels show that the cell produces subthreshold depolarizations in response to current stimuli from 150 to 195 pA, and does not generate an all-or-none action potential until the injected current reaches 200 pA, which is defined as its current threshold. (E) Representative action potential traces recorded from a small DRG neuron expressing N816K mutant hNav1.9 channels show that the current threshold for this cell is 55 pA. (F) There is no significant difference in input resistance between WT and N816K mutant hNav1.9 channels. N816K mutation does not alter the waveforms of action potentials, indicated by (G) action potential amplitude, (H) after-hyperpolarization potential, or (I) half-width of action potentials.