Figure 9.

The length of the conductive parts affects the nociceptive gain by defining the level of Nav1.8 and Nav1.9 conductances. A, left, A trace of the response to the stimulation (red arrow) of the 50 µm terminal branch (yellow) with the Nav1.8 conductance at the control level (100%). Stimulation of the same terminal branch but with increased Nav1.8 (145%) conductance led to higher firing (middle), which was compatible with the stimulation of longer (125 µm) terminal branch with the control (100%) Nav1.8 conductance (right). B, Heatmap representing the relation between the length of the conductive part, the relative level of Nav conductance, and the AP firing measured at the central terminal following stimulation of a single terminal. The AP count is color coded (shown on the right). Note that firing following the stimulation of the terminals with a 100% Nav1.8 conductance is increased when the Nav conductance is increased. Note also that the decrease in Nav1.8 conductance in the long terminal branches, which normally triggers a high number of APs, led to a dramatic reduction of firing. C, D, Same as A, B but showing the relation between Nav1.9 conductance, the conductive part length, and the AP firing at the central terminal.