Localization and function of the Kv3.1b subunit in the rat medulla oblongata: focus on the nucleus tractus solitarii

The voltage-gated potassium channel subunit Kv3.1 confers fast firing characteristics to neurones. Kv3.1b subunit immunoreactivity (Kv3.1b-IR) was widespread throughout the medulla oblongata, with labelled neurones in the gracile, cuneate and spinal trigeminal nuclei. In the nucleus of the solitary...

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Published in:The Journal of physiology 2005-02, Vol.562 (3), p.655-672
Main Authors: Dallas, Mark L., Atkinson, Lucy, Milligan, Carol J., Morris, Neil P., Lewis, David I., Deuchars, Susan A., Deuchars, Jim
Format: Article
Language:English
Subjects:
Action Potentials - physiology
Animals
Electroencephalography
Medulla Oblongata - cytology
Medulla Oblongata - physiology
Molecular and Genomic Physiology
Nerve Tissue Proteins - physiology
Neural Pathways - cytology
Neural Pathways - physiology
Neurons - cytology
Neurons - physiology
Potassium Channels, Voltage-Gated - physiology
Rats
Rats, Wistar
Shaw Potassium Channels
Solitary Nucleus - cytology
Solitary Nucleus - physiology
Synaptic Transmission - physiology
Tissue Distribution
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Summary:The voltage-gated potassium channel subunit Kv3.1 confers fast firing characteristics to neurones. Kv3.1b subunit immunoreactivity (Kv3.1b-IR) was widespread throughout the medulla oblongata, with labelled neurones in the gracile, cuneate and spinal trigeminal nuclei. In the nucleus of the solitary tract (NTS), Kv3.1b-IR neurones were predominantly located close to the tractus solitarius (TS) and could be GABAergic or glutamatergic. Ultrastructurally, Kv3.1b-IR was detected in NTS terminals, some of which were vagal afferents. Whole-cell current-clamp recordings from neurones near the TS revealed electrophysiological characteristics consistent with the presence of Kv3.1b subunits: short duration action potentials (4.2 ± 1.4 ms) and high firing frequencies (68.9 ± 5.3 Hz), both sensitive to application of TEA (0.5 m m ) and 4-aminopyridine (4-AP; 30 μ m ). Intracellular dialysis of an anti-Kv3.1b antibody mimicked and occluded the effects of TEA and 4-AP in NTS and dorsal column nuclei neurones, but not in dorsal vagal nucleus or cerebellar Purkinje cells (which express other Kv3 subunits, but not Kv3.1b). Voltage-clamp recordings from outside-out patches from NTS neurones revealed an outward K + current with the basic characteristics of that carried by Kv3 channels. In NTS neurones, electrical stimulation of the TS evoked EPSPs and IPSPs, and TEA and 4-AP increased the average amplitude and decreased the paired pulse ratio, consistent with a presynaptic site of action. Synaptic inputs evoked by stimulation of a region lacking Kv3.1b-IR neurones were not affected, correlating the presence of Kv3.1b in the TS with the pharmacological effects.
ISSN:0022-3751
1469-7793
DOI:10.1113/jphysiol.2004.073338