Figure 4

Ablation of ANO1 in DRG neurons reduces inflammation-induced excitability of DRG neurons. (A) Example traces of action potentials evoked by current injections to DRG neurons of control mice. Rheobase was determined as a current required for activating the first action potential (red). Depolarizing currents with 5 ms duration were injected to whole cells of DRG neurons from control mice from 50 pA to 1 nA with 50 pA increment (inset). Bath solution contained 140 mM NaCl whereas pipette solution contained 30 mM Cl^- and 50 nM free Ca²⁺ (see Methods). (B) Rheobases of DRG neurons isolated from Adv/Ano1^fl/fl and control mice were measured in the absence (vehicle) or presence of inflammatory soup (IS). Note that the rheobase was lowered in IS-treated DRG neurons both from control and Adv/Ano1^fl/fl mice. But, the reduction in the rheobase in IS- treated DRG neurons from Adv/Ano1^fl/fl mice was significantly less than that of control mice (*p < 0.05, one-way ANOVA, Duncan’s post-hoc test). ***p < 0.001, *p < 0.05 compared to the rheobase of the vehicle-treated DRG neurons. Numbers in parenthesis represent the number of neurons tested. (C) Latencies to first action potential (AP) were measured in DRG neurons of Adv/Ano1^fl/fl and control mice under the condition of absence or presence of inflammatory soup (IS). Current with 1 nA magnitude was injected to evoke the action potential spike. Note that the latency to the first AP was shortened in IS-treated DRG neurons from control mice whereas the latency to the first AP was not changed with IS treatment in DRG neurons from Adv/Ano1^fl/fl mice. *p < 0.05 compared to the latency of vehicle-treated DRG neurons. Number of neurons in each group is same as shown in B. (D) Resting membrane potentials of DRG neurons from Adv/Ano1^fl/fl and control mice were measured under the inflammatory condition. Number of neurons in each group is same as shown in B. *p < 0.05.