High-threshold, Kv3-like potassium currents in magnocellular neurosecretory neurons and their role in spike repolarization
| Autor: | Talent Shevchenko, Ryoichi Teruyama, William E. Armstrong |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Physiology
Potassium chemistry.chemical_element In Vitro Techniques Whole-Cell Recordings Membrane Potentials chemistry.chemical_compound Potassium Channel Blockers Repolarization Animals Elapid Venoms Neurons Communication Tetraethylammonium business.industry General Neuroscience Rats Electrophysiology chemistry Shaw Potassium Channels Potassium Channels Voltage-Gated Spike (software development) Calcium Female business Neuroscience Supraoptic Nucleus |
| Zdroj: | Journal of neurophysiology. 92(5) |
| ISSN: | 0022-3077 |
| Popis: | We identified Kv3-like high-threshold K+ currents in hypothalamic supraoptic neurons using whole cell recordings in hypothalamic slices and in acutely dissociated neurons. Tetraethylammonium (TEA)-sensitive currents (50 of 200–300 nM for both fast and persistent currents. The fast transient current was similar to currents associated with the expression of Kv3.4 subunits, given that it was sensitive to BDS-I (100 nM). The persistent TEA-sensitive current appeared similar to those attributed to Kv3.1/3.2 subunits. Although qualitatively similar, oxytocin (OT) and vasopressin (VP) neurons in slices differed in the stronger presence of persistent current in VP neurons. In both cell types, the IC50 for TEA-induced spike broadening was similar to that observed for current suppression in voltage clamp. However, TEA had a greater effect on the spike width of VP neurons than of OT neurons. Immunochemical studies revealed a stronger expression of the Kv3.1b α-subunit in VP neurons, which may be related to the greater importance of this current type in VP spike repolarization. Because OT and VP neurons are not considered fast firing, but do exhibit frequency- and calcium-dependent spike broadening, Kv3-like currents may be important for maintaining spike width and calcium influx within acceptable limits during repetitive firing. |
| Databáze: | OpenAIRE |
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