Inositol trisphosphate and ryanodine receptors share a common functional Ca2+ pool in cerebellar Purkinje neurons

Kamran Khodakhah, Clay M. Armstrong

Research output: Contribution to journalArticle

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Abstract

Changes in the intracellular free calcium concentration ([Ca2+](i)) control many important processes in excitable and nonexcitable cells. In cerebellar Purkinje neurons, increases in [Ca2+](i) modulate excitability by turning on calcium-activated potassium and chloride conductances, and modifying the synaptic efficacy of inhibitory and excitatory inputs to the cell. Calcium release from the intracellular stores plays an important role in the regulation of [Ca2+](i). Purkinje neurons contain both inositol trisphosphate (InsP3) and ryanodine (Ry) receptors. With the exception of the dendritic spines, where only InsP3 receptors are found, InsP3 and Ry receptors are present in the entire cell. The distribution of the two calcium release channels, however, is not uniform, and it has bean suggested that InsP3 and Ry receptors use separate Ca2+ pools. The functional properties of InsP3 and Ry Ca2+ pools were investigated by flash photolysis and single-cell microspectrofluorimetry. It was found that depletion of ryanodine-sensitive Ca2+ stores renders InsP3 incapable of releasing more Ca2+ from the stores. Abolishing calcium-induced calcium release by blocking ryanodine receptors with ruthenium red did not have a significant effect on InsP3-evoked Ca2+ release. It is concluded that InsP3 receptors use the same functional Ca2+ pool as that utilized by Ry receptors in Purkinje neurons.

Original languageEnglish (US)
Pages (from-to)3349-3357
Number of pages9
JournalBiophysical journal
Volume73
Issue number6
DOIs
Publication statusPublished - Dec 1997
Externally publishedYes

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ASJC Scopus subject areas

  • Biophysics

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