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: Christoph Lossin
• Journal: Muscle & nerve (Muscle Nerve) Vol. 47 Issue 4 Pg. 483-7 (Apr 2013) ISSN: 1097-4598 [Electronic] United States
• PMID: 23381896 (Publication Type: Journal Article)
• Copyright: Copyright © 2012 Wiley Periodicals, Inc.

Chemical References

• CLC-1 channel
• Chloride Channels
• NAV1.4 Voltage-Gated Sodium Channel
• SCN4A protein, human

Topics

• Chloride Channels (metabolism)
• Humans
• Muscle Fibers, Skeletal (metabolism)
• Muscle, Skeletal (metabolism, physiopathology)
• Myotonia (metabolism, physiopathology)
• Myotonic Disorders (metabolism, physiopathology)
• NAV1.4 Voltage-Gated Sodium Channel (genetics, metabolism)