Removal of Ca2+ following depolarization-evoked cytoplasmic Ca2+ transients in freshly dissociated pyramidal neurones of the rat dorsal cochlear nucleus

Csaba Harasztosi, Ágnes Pór, Zoltán Rusznák, Géza Szûcs

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2 Citations (Scopus)

Abstract

Cytoplasmic [Ca2+] ([Ca2+]i) was measured using Fura-2 in pyramidal neurones isolated from the rat dorsal cochlear nucleus (DCN). The kinetic properties of Ca2+ removal following K+ depolarization-induced Ca2+ transients were characterized by fitting exponential functions to the decay phase. The removal after small transients (<82 nM peak [Ca2+]i) had monophasic time course (time constant of 6.43±0.48 s). In the cases of higher Ca2+ transients biphasic decay was found. The early time constant decreased (from 3.09±0.26 to 1.46±0.11 s) as the peak intracellular [Ca2+] increased. The value of the late time constant was 18.15±1.60 s at the smallest transients, and showed less dependence on [Ca2+]i. Blockers of Ca2+ uptake into intracellular stores (thapsigargin and cyclopiazonic acid) decreased the amplitude of the Ca2+ transients and slowed their decay. La3+ (3 mM) applied extracellularly during the declining phase dramatically changed the time course of the Ca2+ transients as a plateau developed and persisted until the La3+ was present. When the other Ca2+ removal mechanisms were available, reduction of the external [Na+] to inhibit the Na+/Ca2+ exchange resulted in a moderate increase of the time constants. It is concluded that in the isolated pyramidal neurones of the DCN the removal of Ca2+ depends mainly on the activity of Ca2+ pump mechanisms.

Original languageEnglish
Pages (from-to)123-133
Number of pages11
JournalBrain research
Volume930
Issue number1-2
DOIs
Publication statusPublished - Mar 15 2002

Keywords

  • Ca-induced Ca release
  • Fura-2
  • Na/Ca exchange
  • PMCA
  • SERCA pump

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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