Stimulation of calcium uptake in cultured astrocytes by hypoosmotic stress - effect of cyclic AMP

Alex S. Bender, Lily L. Mantelle, Michael D. Norenberg

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

To investigate the role of Ca2+ in astrocyte volume regulation, we determined Ca2+ fluxes following hypoosmotic stress and how these fluxes were modified by cyclic AMP. In isoosmotic conditions treatment with dibutyryl cyclic AMP (dBcAMP) caused almost a twofold increase in 45Ca2+ uptake. Efflux studies of 45Ca2+ in dBcAMP-treated cells showed three Ca2+ compartments while only two Ca2+ compartments were identified in non-dBcAMP-treated cells. Following hypoosmotic stress a twofold stimulation of 45Ca2+ uptake occurred in both non-dBcAMP-treated and dBcAMP-treated astrocytes. Stimulation of Ca2+ uptake begins at ∼ 270 mOsm and is half-maximally stimulated at ∼ 100 mOsm. This uptake is partly mediated through L-type 'slow' inactivating Ca2+ channels. Hypoosmotic stress also induces the release of Ca2+ from intracellular stores. The influx of extracellular Ca2+ and efflux of intracellular Ca2+ appear to be important factors in volume regulation after hypoosmotic stress. Cyclic AMP plays an important role in modulating hypoosmotically stimulated Ca2+ uptake.

Original languageEnglish (US)
Pages (from-to)27-35
Number of pages9
JournalBrain Research
Volume645
Issue number1-2
DOIs
StatePublished - May 9 1994

Keywords

  • Astrocyte
  • Calcium flux
  • Cellular calcium compartment
  • Dibutyryl cyclic adenosine-3′,5′-monophosphate
  • Hypoosmotic stress
  • Volume regulation

ASJC Scopus subject areas

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

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