Kv1.4 subunit expression is decreased in neurons of painful human pulp

Kv1.4, a subunit of voltage-gated K(+) channels, plays a large role in regulating neuronal excitability. The level of Kv1.4 expression is unknown in human sensory neurons innervating healthy or painful tissue. Therefore, we examined Kv1.4 immunoreactivity in axons innervating both clinically diagnosed asymptomatic and painful symptomatic human tooth pulp. Antibodies directed against Kv1.4 and PGP9.5, a protein marker for axons, was used to determine the proportion of PGP9.5 immunopositive tissue that was also immunopositive for Kv1.4. We report that on pulpal axons innervating symptomatic teeth Kv1.4 immunoreactivity, a correlate of decreased Kv1.4 expression, is significantly decreased (p < 0.0001), suggestive of a factor responsible for facilitating chronic dental pain and decreases in currents produced, such as I(A), in neurons innervating painful pulp.