Figure 4. Mechanically evoked and ASIC-mediated fast excitatory synaptic transmission at MNCs drives SA1 impulses at Aβ-afferent terminals.

A) Trace exemplifies APs and EPSPs evoked by a mechanical step at 10 μm applied to rat MNCs. Red and orange arrows indicate an AP and an EPSP, respectively. B) Plot of instantaneous frequency of APs shown in A during the 5 s of 10-μm mechanical step. C) Coefficient of variance of the inter-event intervals of APs evoked by the 10-μm mechanical step in 5 s. D&E) Numbers of APs (D) and EPSPs (E) evoked by mechanical steps at 0, 1, 2, 5, and 10 μm each for 5 s (circles). The squares in D and E are responses to 10-μm mechanical steps in recordings performed at 34°C. F) Traces exemplify APs evoked by a 10-μm mechanical step in the absence (top) and presence (bottom) of 200 μM amiloride. G) Pooled data of the number of APs (left) and EPSP amplitude (right) in 5 s following the 10-μm mechanical step in the absence (control) and presence of 200 μM amiloride. H) Pooled data of the number of APs (left) and EPSP amplitude (right) in 5 s following the 10-μm mechanical step in the absence (control) and presence of 100 μM diminazene. In A-H, Current-clamp recordings were applied to the 1^st nodes. I-K) Single fiber recordings from afferent fibers in whisker hair follicles (I) show that 200 μM amiloride (J) and 100 μM diminazene (K) abolished AP impulses evoked by whisker hair deflection at 200 μm. Data represent independent observations and mean ± SEM, *p < 0.05, ***p < 0.05, the paired Student’s t-test.