5 – The Roles of Potassium and Calcium Channels in Physiology and Pathophysiology of Axons

This chapter provides an overview of our current knowledge of the physiology and pathophysiology of ion channels on myelinated axons as they relate to demyelinating diseases. This chapter discusses three major classes of ion channels on axons of mammalian myelinated fibers and their roles in normal axons and pathological axons in multiple sclerosis (MS). These axonal ion channels Na, K, and Ca are potential targets in therapeutic treatment of multiple sclerosis. Deficiency of Na channel in the internodes contributes to conduction block, their plasticity in gene expression contributes to abnormal firing patterns in MS, and their linkage to Ca homeostasis might contribute to Ca-mediated axonal injury. Next, coming to the K channels, most of which are sealed by myelin in a normal nerve, has best functional analysis carried out for the juxtaparanodal Kv1.1. The Ca channels may translate nerve activity into graded axonal Ca elevation that can drive various processes including axonal elongation and axonal transport. Pharmacological manipulation of these three channels can produce short-term neurological effects and changes in glial-axon relationship that might be beneficiary for long-term functional restoration