title: Chronic compression of mouse dorsal root ganglion alters voltage-gated sodium and potassium currents in medium-sized dorsal root ganglion neurons.
abstract: Chronic compression (CCD) of the dorsal root ganglion (DRG) is a model of human radicular pain produced by intraforaminal stenosis and other disorders affecting the DRG, spinal nerve, or root. Previously, we examined electrophysiological changes in small-diameter lumbar level 3 (L3) and L4 DRG neurons treated with CCD; the present study extends these observations to medium-sized DRG neurons, which mediate additional sensory modalities, both nociceptive and non-nociceptive. Whole-cell patch-clamp recordings were obtained from medium-sized somata in the intact DRG in vitro. Compared with neurons from unoperated control animals, CCD neurons exhibited a decrease in the current threshold for action potential generation. In the CCD group, current densities of TTX-resistant and TTX-sensitive Na(+) current were increased, whereas the density of delayed rectifier voltage-dependent K(+) current was decreased. No change was observed in the transient or "A" current after CCD. We conclude that CCD in the mouse produces hyperexcitability in medium-sized DRG neurons, and the hyperexcitability is associated with an increased density of Na(+) current and a decreased density of delayed rectifier voltage-dependent K(+) current.
authors.affiliation: Department of Anesthesiology, Yale University School of Medicine, 333 Cedar St., P.O. 208051, New Haven, CT 06520, USA.
authors.forename: Ni
authors.initials: N
authors.lastname: Fan
authors.forename: David F
authors.initials: DF
authors.lastname: Donnelly
authors.forename: Robert H
authors.initials: RH
authors.lastname: LaMotte
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001703:Biophysics; D004195:Disease Models, Animal; D004558:Electric Stimulation; D007839:Functional Laterality; D005727:Ganglia, Spinal / Q000473:pathology*; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D009474:Neurons / Q000145:classification / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology; D024642:Potassium Channels, Voltage-Gated / Q000378:metabolism*; D011843:Radiculopathy / Q000473:pathology*; D026941:Sodium Channel Blockers / Q000494:pharmacology; D015222:Sodium Channels / Q000378:metabolism*; D019789:Tetraethylammonium / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D026902:Potassium Channel Blockers; D024642:Potassium Channels, Voltage-Gated; D026941:Sodium Channel Blockers; D015222:Sodium Channels; D013779:Tetrodotoxin; D019789:Tetraethylammonium