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J Comput Neurosci. 2009 Feb;26(1):139-47. doi: 10.1007/s10827-008-0103-9. Epub 2008 Jun 18.

Calcium sensitive non-selective cation current promotes seizure-like discharges and spreading depression in a model neuron.

Author information

1
Department of Cell Biology, Duke University Medical Center, Box 3011, Durham, NC 27710, USA. g.somjen@cellbio.duke.edu

Abstract

As described by others, an extracellular calcium-sensitive non-selective cation channel ([Ca(2+)](o)-sensitive NSCC) of central neurons opens when extracellular calcium level decreases. An other non-selective current is activated by rising intracellular calcium ([Ca(2+)]( i )). The [Ca(2+)](o)-sensitive NSCC is not dependent on voltage and while it is permeable by monovalent cations, it is blocked by divalent cations. We tested the hypothesis that activation of this channel can promote seizures and spreading depression (SD). We used a computer model of a neuron surrounded by interstitial space and enveloped in a glia-endothelial "buffer" system. Na(+), K(+), Ca(2+) and Cl(-) concentrations, ion fluxes and osmotically driven volume changes were computed. Conventional ion channels and the NSCC were incorporated in the neuron membrane. Activation of NSCC conductance caused the appearance of paroxysmal afterdischarges (ADs) at parameter settings that did not produce AD in the absence of NSCC. The duration of the AD depended on the amplitude of the NSCC. Similarly, NSCC also enabled the generation of SD. We conclude that NSCC can contribute to the generation of epileptiform events and to spreading depression.

PMID:
18563545
DOI:
10.1007/s10827-008-0103-9
[Indexed for MEDLINE]

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