Figure 2. Fast excitatory synaptic transmission at MNCs is mediated by ASICs.

A) Traces exemplify MA currents and EPSCs of rat MNCs recorded at −70, −40, −10, 20, and 50 mV. Mechanical step of 10 μm was applied for 5 s to MNCs. Blue arrows indicate MA currents and red arrows indicate EPSCs. B) I-V curve (n = 6) of both MA currents (blue circles) and EPSCs (red squares) at different voltages. C) Similar to B except that the EPSCs were recorded from mouse MNCs (n = 4). D) Traces exemplify EPSCs of a rat MNC recorded at −70 and 20 mV in [Na⁺]_o/[Na⁺]_in = 5 (top) and [Na⁺]_o/[Na⁺]_in = 1 (bottom). E) I-V curve (n = 5) shows a shift of the reversal potential with the change of [Na⁺]_o/[Na⁺]_in. The recordings were performed in the presence of 10 mM caffeine. F) Traces exemplify mechanically evoked EPSCs of rat MNCs in the absence (control, top) and presence of the ASIC blocker amiloride (200 μM, bottom). G) Pooled data of the amplitudes (left) and frequency (right) of mechanically evoked EPSCs of rat MNCs in the absence (control) and presence of 200 μM amiloride. H) Similar to G, except EPSCs of mouse MNCs were tested. I) Summary data of the amplitude (left) and frequency (right) of mechanically evoked EPSCs of MNCs in the absence (control) and presence of 200 μM amiloride, 100 μM diminazene, and 100 μM nafamostat. J) Summary data of the amplitude (left) and frequency (right) of mechanically evoked EPSCs in the absence (control) and presence of the adrenergic β2 receptor antagonist ICI118551 (50 μM), and 5-HT3 receptor blocker VUF10166 (20 μM). The mechanical step was applied to MNCs at 10 μm for 5 s. The 1^st nodes of MNCs were voltage-clamped at −72 mV (F-J) or −69 mV (H). Data represent independent observations and mean ± SEM, *p < 0.05, **p < 0.01, ***p < 0.001, ns, not significantly different, paired Student’s t-test or one-way ANOVA with Bonferroni post hoc test. See also Figure S2–4.