Molecular identities of two tetrodotoxin-resistant sodium channels in corneal axons

Exp Eye Res. 2002 Aug;75(2):193-9. doi: 10.1006/exer.2002.2014.

Abstract

Previous electrophysiological studies have demonstrated that tetrodotoxin-resistant (TTX-R) sodium channels contribute to action potential electrogenesis and conduction along non-myelinated PNS axons. Moreover, recent work has established that TTX-R sodium channels play a major role in the generation of action potentials in the terminals of non-myelinated nociceptive axons innervating the cornea. We have utilized subtype-specific antibodies to sodium channels Na(v)1.8 and Na(v)1.9 to examine the molecular identity of the TTX-R sodium channels that are present in these axons. Both Na(v)1.8 and Na(v)1.9 sodium channels are expressed diffusely along the entire lengths of non-myelinated corneal axons, from the nerve plexus at the corneoscleral limbus to the distal corneal leash fibers. Moreover, both Na(v)1.8 and Na(v)1.9 are localized at the bulb-like nerve terminals of the leash fibers within the superficial epithelial layers of the cornea. These observations suggest that both TTX-R sodium channels Na(v)1.8 and Na(v)1.9 contribute to the electrogenesis of non-myelinated axons of the cornea.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Action Potentials
  • Animals
  • Antibodies
  • Axons / immunology
  • Axons / metabolism*
  • Cornea / immunology
  • Cornea / innervation*
  • Cornea / metabolism
  • Fluorescent Antibody Technique
  • Male
  • Microscopy, Confocal
  • Rats
  • Rats, Sprague-Dawley
  • Sodium Channels / immunology
  • Sodium Channels / metabolism*
  • Tetrodotoxin / metabolism*

Substances

  • Antibodies
  • Sodium Channels
  • Tetrodotoxin