title: Nav 1.4 slow-inactivation: is it a player in the warm-up phenomenon of myotonic disorders?
abstract: Myotonia is a heritable disorder in which patients are unable to willfully relax their muscles. The physiological basis for myotonia lies in well-established deficiencies of skeletal muscle chloride and sodium conductances. What is unclear is how normal muscle function can temporarily return with repeated movement, the so-called "warm-up" phenomenon. Electrophysiological analyses of the skeletal muscle voltage-gated sodium channel Nav 1.4 (gene name SCN4A), a key player in myotonia, have revealed several parallels between the Nav 1.4 biophysical signature, specifically slow-inactivation, and myotonic warm-up, which suggest that Nav 1.4 is critical not only in producing the myotonic reaction, but also in mediating the warm-up.
authors: Department of Neurology, University of California Davis School of Medicine, 4635 Second Avenue, Room 1004A, Sacramento, California 95817, USA.
authors: Christoph
authors: C
authors: Lossin
mesh_terms: D018118:Chloride Channels / Q000378:metabolism; D006801:Humans; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000503:physiopathology; D009222:Myotonia / Q000378:metabolism* / Q000503:physiopathology; D020967:Myotonic Disorders / Q000378:metabolism* / Q000503:physiopathology; D062553:NAV1.4 Voltage-Gated Sodium Channel / Q000235:genetics / Q000378:metabolism*
chemical_list: C086321:CLC-1 channel; D018118:Chloride Channels; D062553:NAV1.4 Voltage-Gated Sodium Channel; C106251:SCN4A protein, human