Effect of dantrolene on KCl- or NMDA-induced intracellular Ca2+ changes and spontaneous Ca2+ oscillation in cultured rat frontal cortical neurons

Abstract

Dantrolene has been known to affect intracellular Ca2+ concentration ([Ca2+]i) by inhibiting Ca2+ release from intracellular stores in cultured neurons. We were interested in examining this property of dantrolene in influencing the [Ca2+]i affected by the NMDA receptor ligands, KCl, L-type Ca2+ channel blocker nifedipine, and two other intracellular Ca2(+)-mobilizing agents caffeine and bradykinin. Effect of dantrolene on the spontaneous oscillation of [Ca2+]i was also examined. Dantrolene in microM concentrations dose-dependently inhibited the increase in [Ca2+]i elicited by NMDA and KCl. AP-5, MK-801 (NMDA antagonists), and nifedipine respectively reduced the NMDA and KCl-induced increase in [Ca2+]i. Dantrolene, added to the buffer solution together with the antagonists or nifedipine, caused a further reduction in [Ca2+]i to a degree similar to that seen with dantrolene alone inhibiting the increase in [Ca2+]i caused by NMDA or KCl. At 30 microM, dantrolene partially inhibited caffeine-induced increase in [Ca2+]i whereas it has no effect on the bradykinin-induced change in [Ca2+]i. The spontaneous oscillation of [Ca2+]i in frontal cortical neurons was reduced both in amplitude and in base line concentration in the presence of 10 microM dantrolene. Our results indicate that dantrolene's mobilizing effects on intracellular Ca2+ stores operate independently from the influxed Ca2+ and that a component of the apparent increase in [Ca2+]i elicited by NMDA or KCl represents a dantrolene-sensitive Ca2+ release from intracellular stores. Results also suggest that dantrolene does not affect the IP3-gated release of intracellular Ca2+ and that the spontaneous Ca2+ oscillation is, at least partially, under the control of Ca2+ mobilization from internal stores.

Searching for Mechanisms of N-Methyl-d-Aspartate-Induced Glutathione Efflux in Organotypic Hippocampal Cultures

“…Dantrolene, a blocker of ryanodine receptor-dependent Ca 2+ release, attenuates the NMDA-mediated rise in intracellular Ca 2+ (66). As in our previous experiments with acute hippocampal slices, dantrolene did not change glutathione, PEA, or taurine efflux rates, suggesting that the efflux rate is not regulated by ryanodine receptor-dependent Ca 2+ release.…”

Ca2+-dependent Translocation of the Calcyclin-binding Protein in Neurons and Neuroblastoma NB-2a Cells

“…1, A and D); this staining pattern was observed in the majority of the cells (Table I). The level of [Ca 2ϩ ] i in rat cortical neurons has been established previously to be ϳ50 nM in resting cells and above 300 nM upon KCl activation (27). We observed that activation of cultured cortical neurons by KCl induces CacyBP translocation mainly to the perinuclear region (Fig.…”

“…The intracellular Ca 2ϩ level in cultured rat cortical neurons is ϳ50 nM and upon KCl stimulation increases to above 300 nM (27). Similar low levels of resting [Ca 2ϩ ] i were measured in hippocampal neurons (80 nM) (28) and hypothalamic neurons (54 or 69 nM) (29,30 (32).…”

Extracellular-derived calcium does not initiate in vivo neurotransmission involving docosahexaenoic acid

“…In agreement, exposure of eosinophilic leukemia cells or platelets to a Ca 2+ -ionophore did not release DHA while releasing AA through cPLA 2 activation ( 9 ), and chronic NMDA administration to rats increased cPLA 2 -IVA but not iPLA 2 -VI expression in brain ( 43 ). Under some in vitro conditions, acute NMDA receptor activation may release Ca 2+ from intracellular stores by Ca 2+ -induced Ca 2+ release (CICR) ( 44,45 ), which may indirectly stimulate iPLA 2 (46)(47)(48). However, our in vivo data do not support this signaling pathway with the dose of NMDA administered.…”