Sodium channel expression: a dynamic process in neurons and non-neuronal cells.

Although voltage-gated sodium channels have been most carefully studied in neurons, these channels are also present in nonexcitable cells within the nervous system and outside the nervous system. The mRNAs and protein for rat brain type sodium channels are expressed in both non-neuronal nervous system cells (glial cells) and in some cell types outside the nervous system. In most of these cell types, the expression of sodium channels is dynamic, with the levels and proportions of various sodium channel subtypes changing during development, and in response to injury and upon exposure to neurotrophins. It is likely that, in the near future, we will understand the roles played by sodium channels in each of these cell types, and the regulatory mechanisms that control expression of these channels.