title: Distribution of sodium channels during nerve elongation in rat peripheral nerve.
abstract: A number of studies have investigated electrophysiological and morphological changes of peripheral nerves during gradual elongation. There has been, however, no report on the distribution of sodium channels at Ranvier's nodes during peripheral nerve elongation. We investigated peripheral nerve injury after the gradual elongation of rat sciatic nerves. Indirect nerve elongation was induced by leg lengthening at a rate of 3 mm/day by 15 or 30 mm. At 7 days after the leg lengthening, the electrophysiological properties of sciatic nerves, the ultrastructures of the Ranvier's nodes and axons, and the distribution of voltage-dependent sodium channels were examined. In the control nerves, most sodium channels were localized at Ranvier's nodes in myelinated axons, providing the physiological basis of saltatory conduction. In the elongated nerves, both the amplitude and conduction velocity of compound nerve action potential decreased following leg lengthening. The elongated nerves also showed paranodal demyelination in Ranvier's nodes longer than those in the control group. In addition, the distribution of sodium channels became diffuse or disappeared at Ranvier's nodes of elongated nerves. The diffuse distribution and/or disappearance of sodium channels may underlie the electrophysiological changes in compound nerve action potential induced by nerve elongation.
authors.affiliation: Department of Orthopaedic Surgery, Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, 305-8575, Japan.
authors.forename: Harumitsu
authors.initials: H
authors.lastname: Ichimura
authors.forename: Takashi
authors.initials: T
authors.lastname: Shiga
authors.forename: Ichiro
authors.initials: I
authors.lastname: Abe
authors.forename: Yuki
authors.initials: Y
authors.lastname: Hara
authors.forename: Naoto
authors.initials: N
authors.lastname: Terui
authors.forename: Akihito
authors.initials: A
authors.lastname: Tsujino
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Ochiai
mesh_terms: D000818:Animals; D001852:Bone Lengthening; D008297:Male; D008854:Microscopy, Electron; D019637:Orthopedic Procedures; D010525:Peripheral Nerves / Q000601:surgery*; D011901:Ranvier's Nodes / Q000737:chemistry / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar; D015222:Sodium Channels / Q000032:analysis
chemical_list: D015222:Sodium Channels