Ion channels are fundamental to the correct functioning of nerves. A high density of Na,, channels at nodes of Ranvier is crucial for generating sufficient local current to initiate a self-regenerating action potential. K,7 (KCNQ) channels are also functional components of nodes of Ranvier and contribute to the repolarization of the action potential. Paranodes underlying the paranodal loops have no channels whereas K(v)1.1 and K-v1.2 channels cluster at juxtaparanodes. The disruption of the normal balance of different channels causes the inappropriate nerve activity that underlies a variety of nervous system diseases. Axonal voltage-dependent channels, nodal Na-v, and juxtaparanodal K-v channels disperse after the nerve injury and reorganize with regeneration. (C) 2007 Elsevier B.V. All rights reserved.