Figure 1. CAPs recorded from mouse vagus nerve reveal three distinct axon populations.
A, as the stimulation intensity is increased, three waves become visible in CAPs recorded from wild-type mouse vagus nerve. These peaks result from recruitment of A-, Aδ- and C-axons. The A- and Aδ-axons correspond to larger (>4 μm) and smaller (2–4 μm) diameter myelinated axons, respectively. The C wave corresponds to non-myelinated axons (<2 μm). A-axons exhibited the lowest firing thresholds, followed by the Aδ- and C-axons, which required higher stimulation intensities to fire APs. B, nerves lacking Kv1.1 channels showed similar waveforms for all three axon groups in CAP recordings compared to wild-type nerves. C, each axon population exhibited a characteristic conduction velocity (mean ± SD) that varied with temperature and showed no change in the absence of Kv1.1 channels. The larger, myelinated A-axons conducted APs about three times faster than the smaller, myelinated Aδ-axons, which conducted APs about three times faster than the non-myelinated C-axons.