Localization of the tetrodotoxin-resistant sodium channel NaN in nociceptors

Terrodotoxin-resistant sodium currents contribute to the somal and axonal s odium currents of small diameter primary sensory neurons, many of which are nociceptive. NaN is a recently described tetrodotoxin-resistant sodium cha nnel expressed preferentially in IB4-labeled dorsal root ganglion (DRG) neu rons. We employed an antibody raised to a NaN specific peptide to show that NaN is preferentially localized along axons of IB4-positive unmyelinated f ibers in the sciatic nerve and in axon terminals in the cornea. NaN immunor eactivity was also found at some nodes of Ranvier of thinly myelinated axon s of the sciatic nerve, where it was juxtaposed to Kv1.2 potassium channel immunoreactivity. This distribution of NaN is consistent with a role for Na N sodium channels in nociceptive transmission. NeuroReport 11:199-202 (C) 2 000 Lippincott Williams & Wilkins.