Potassium-depolarization-induced cytoplasmic [Ca2+] transients in freshly dissociated pyramidal neurones of the rat dorsal cochlear nucleus

Zoltán Rusznák, Csaba Harasztosi, Peter R. Stanfield, László Kovács, Géza Szûcs

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Abstract

The significance of voltage-activated Ca2+ currents in eliciting cytoplasmic Ca2+ transients was studied in pyramidal neurones isolated from the rat dorsal cochlear nucleus using combined enzyme treatment/mechanical trituration. Increases in cytoplasmic Ca2+ concentration ([Ca2+](i)) were evoked by K+-induced depolarizations (10-50 mM) and monitored by the Fura2 fluorimetric technique. The acutely dissociated neurones had a resting [Ca2+](i) of 17.2±0.5 nM. They possessed caffeine-sensitive Ca2+ stores which were empty at rest; these stores could be filled with Ca2+ entering from the extracellular space and were re-emptied quickly. The effects of various specific high-voltage-activated (HVA) Ca2+ channel antagonists (nifedipine, ω-agatoxin IVA and ω-conotoxin GVIA) on [Ca2+](i) transients were tested. Analysis of the blocking effects of these agents on the [Ca2+](i) transients indicates that, in the pyramidal neurones of the dorsal cochlear nucleus, N-type Ca2+ channels are primarily responsible for producing the depolarization-induced increases in [Ca2+](i).

Original languageEnglish
Pages (from-to)462-466
Number of pages5
JournalPflugers Archiv European Journal of Physiology
Volume440
Issue number3
DOIs
Publication statusPublished - Jan 1 2000

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Keywords

  • Ca channel blockers
  • Cytoplasmic [Ca] transients
  • Fura-2
  • N-type Ca channels
  • Voltage-gated Ca channels

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

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