Skip to main content
. 2021 Dec 27;145(10):3637–3653. doi: 10.1093/brain/awab482

Figure 6.

Figure 6

Selective small molecule inhibition of Nav1.7 currents results in hypo-excitable C-LTMR sensory endings. (A) DRG neuronal cultures were made from genetically labelled C-LTMRs (THCreERT2Ai32/eYFP) and used for subsequent voltage clamp analysis. (B) Top, During the voltage-clamp protocol, neurons were depolarized to −75 mV from a holding potential of −120 mV for 8 s (to inactivate a proportion of Nav1.7 channels), followed by a 2 ms recovery step to −120 mV and a test pulse to 0 mV. Bottom, Example traces of total sodium currents induced during the test pulse (shaded region of protocol schematic) in the presence of vehicle or PF-05089771 (10 nM). (C) Quantification of the sodium current densities in wildtype C-LTMRs in the presence of vehicle or PF-05089771. Blockage of Nav1.7 using PF-05089771 in C-LTMRs results in a significant reduction in the sodium current density compared to vehicle treated C-LTMRs (Vehicle: n = 16 cells, PF-05089771: n = 17 cells, Mann–Whitney U-test, U = 49, P = 0.0012, **) (D) Example illustration of single-fibre C-LTMR recordings from WT mice. C-LTMRs were identified and subsequently recorded following a 10 min incubation of vehicle or PF-05089771 (10 nM) applied directly to the isolated receptive field. (E) C-LTMR mechanical thresholds pre and post vehicle or PF-05089771. Small molecule inhibition of Nav1.7 in C-LTMR sensory endings results in a significant increase in the mechanical threshold compared to vehicle. [Vehicle: n = 10 units, PF-05089771: n = 9 units, repeated measures two-way ANOVA F(1, 17) = 12.66, P = 0.0024, **, with Bonferroni post hoc tests, vehicle pre versus post: t = 0.151, P = > 0.99, n.s, PF-05089771 pre versus post, t = 5.82, P = <0.0001, ***]. (F) The increasing force stimulus-response function showing that PF-05089771 treated C-LTMRs are significantly hypo-excitable to supra-threshold stimuli compared to vehicle treated C-LTMRs [Vehicle n = 10 units, PF-05089771 n = 9 units, two-way ANOVA, F(1, 68) = 6.95, P = 0.0104, *]. All data represented as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001.