Kv3 channels contribute to the delayed rectifier current in small cultured mouse dorsal root ganglion neurons.
Delayed rectifier voltage-gated K(+) (K(V)) channels are important determinants of neuronal excitability. However, the large number of K(V) subunits poses a major challenge to establish the molecular composition of the native neuronal K(+) currents. A large part (∼60%) of the delayed rectifier current (I(K)) in small mouse dorsal root ganglion (DRG) neurons has been shown to be carried by both homotetrameric K(V)2.1 and heterotetrameric channels of K(V)2 subunits with silent K(V) subunits (K(V)S), while a contribution of K(V)1 channels has also been demonstrated. Because K(V)3 subunits also generate delayed rectifier currents, we investigated the contribution of K(V)3 subunits to I(K) in small mouse DRG neurons. After stromatoxin (ScTx) pretreatment to block the K(V)2-containing component, application of 1 mM TEA caused significant additional block, indicating that the ScTx-insensitive part of I(K) could include K(V)1, K(V)3, and/or M-current channels (KCNQ2/3). Combining ScTx and dendrotoxin confirmed a relevant contribution of K(V)2 and K(V)2/K(V)S, and K(V)1 subunits to I(K) in small mouse DRG neurons. After application of these toxins, a significant TEA-sensitive current (∼19% of total I(K)) remained with biophysical properties that corresponded to those of K(V)3 currents obtained in expression systems. Using RT-PCR, we detected K(V)3.1-3 mRNA in DRG neurons. Furthermore, Western blot and immunocytochemistry using K(V)3.1-specific antibodies confirmed the presence of K(V)3.1 in cultured DRG neurons. These biophysical, pharmacological, and molecular results demonstrate a relevant contribution (∼19%) of K(V)3-containing channels to I(K) in small mouse DRG neurons, supporting a substantial role for K(V)3 subunits in these neurons.
Laboratory for Molecular Biophysics, Physiology and Pharmacology, Department of Biomedical Sciences, University of Antwerp, Campus Drie Eiken, Belgium.
Elke
E
Bocksteins
Gerda
G
Van de Vijver
Pierre-Paul
PP
Van Bogaert
Dirk J
DJ
Snyders
D000818:Animals; D002478:Cells, Cultured; D005727:Ganglia, Spinal / Q000166:cytology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D021122:Protein Subunits; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051670:Shaw Potassium Channels / Q000502:physiology*; D019789:Tetraethylammonium
D026902:Potassium Channel Blockers; D021122:Protein Subunits; D012333:RNA, Messenger; D051670:Shaw Potassium Channels; D019789:Tetraethylammonium