The voltage-gated ‘glial’ sodium channel NaG belongs to a distinct molecular class within the multi-gene
family of mammalian sodium channels. Originally found in central and peripheral glia, NaG has since been
detected in neurons in rat dorsal root ganglia (DRG) and may play a role in Schwann cell-axon interactions.
We have studied the presence of NaG-like immunoreactivity in the intact and injured human peripheral
nervous system using a specific affinity-purified antibody. Nerve fibres in normal and injured peripheral
nerves and normal skin exhibited intense NaG-immunoreactivity. Numerous NaG-immunoreactive nerve
fibres surrounded neuronal cell bodies within postmortem control DRG, and in DRG avulsed from the
spinal cord (i.e. after traumatic central axotomy). There were no significant differences in the pattern of
NaG immunostaining between control and avulsed DRG, or with delay after injury. Generally, the neuronal
cell bodies were only very weakly immunoreactive to NaG, indicating that the NaG immunoreactivity was
predominantly in Schwann cells/myelin. In accord, we demonstrated NaG immunostaining in cultured
human and rat Schwann cells, and in distal nerve after wallerian degeneration. NaG thus appears to be a
useful new marker for Schwann cells in the human PNS, and a role in neuropathy deserves investigation.