Neuromodulation of Na+ channels: An unexpected form of cellular plasticity

Voltage-gated Na+ channels set the threshold for action potential generatio n and are therefore good candidates to mediate forms of plasticity that aff ect the entire neuronal output. Although early studies led to the idea that Na+ channels were not subject to modulation, we now know that Na+ channel function is affected by phosphorylation. Furthermore, Na+ channel modulatio n is implicated in the control of input-output relationships in several typ es of neuron and seems to be involved in phenomena as varied as cocaine wit hdrawal, hyperalgesia and light adaptation. Here we review the available ev idence for the regulation of Na+ channels by phosphorylation, its molecular mechanism, and the possible ways in which it affects neuronal function.