Localization of the Nav1.8 sodium channel isoform at nodes of Ranvier in normal human radicular tooth pulp.
The activation of voltage-gated sodium channels is necessary for action potential propagation and multiple sodium channel isoforms have been identified that show a differential distribution throughout the nervous system. An evaluation of sodium channel localization in the radicular pulp from normal human extracted third molars established the presence of the Na(v)1.8 isoform at nodes of Ranvier in a subpopulation of the myelinated axons as demonstrated with immunofluorescence confocal microscopy. A caspr antibody was used to identify the paranodal region of nodes of Ranvier and quantitative analysis revealed that 16.5% of the nodes contained significant Na(v)1.8 immunoreactivity. Since the Na(v)1.6 isoform has been described as the predominant sodium channel at essentially all nodes, the finding of Na(v)1.8 in a subpopulation of nodes suggests that multiple isoforms may coexist at some nodes of Ranvier and also suggests that this isoform may be an important nodal sodium channel type in the peripheral sensory nervous system of humans.
Henry
Michael A
MA
Department of Surgical Dentistry, School of Dentistry, University of Colorado Health Sciences Center, Denver, CO 80262, USA. Michael.henry@uchsc.edu
Sorensen
Howard J
HJ
Johnson
Lonnie R
LR
Levinson
S Rock
SR
D016001:Confidence Intervals; D003782:Dental Pulp / Q000166:cytology*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008869:Microtubule-Associated Proteins; D062559:NAV1.8 Voltage-Gated Sodium Channel; D009414:Nerve Growth Factors / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism; D011901:Ranvier's Nodes / Q000378:metabolism*; D015222:Sodium Channels / Q000378:metabolism
D008869:Microtubule-Associated Proteins; C477056:NAV1 protein, human; D062559:NAV1.8 Voltage-Gated Sodium Channel; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; C568317:SCN10A protein, human; D015222:Sodium Channels