Amplified Mechanically Gated Currents in Distinct Subsets of Myelinated Sensory Neurons following In Vivo Inflammation of Skin and Muscle.

Primary afferents are sensitized to mechanical stimuli following in vivo inflammation, but whether sensitization of mechanically gated ion channels contributes to this phenomenon is unknown. Here we identified two populations of murine A fiber-type sensory neurons that display markedly different responses to focal mechanical stimuli of the membrane based on their expression of calcitonin gene-related peptide (CGRP). Following inflammation of the hindpaw, myelinated, CGRP-positive neurons projecting to the paw skin displayed elevated mechanical currents in response to mechanical stimuli. Conversely, muscle inflammation markedly amplified mechanical currents in myelinated, CGRP-negative neurons projecting to muscle. These data show, for the first time, that mechanically gated currents are amplified following in vivo tissue inflammation, and also suggest that mechanical sensitization can occur in myelinated neurons after inflammation.