Circadian dynamics of cytosolic and nuclear Ca2+ in single suprachiasmatic nucleus neurons

Masayuki Ikeda, Takashi Sugiyama, Christopher S. Wallace, Heinrich S. Gompf, Tohru Yoshioka, Atsushi Miyawaki, Charles N. Allen

Research output: Contribution to journalArticlepeer-review

235 Scopus citations


Intracellular free Ca2+ regulates diverse cellular processes, including membrane potential, neurotransmitter release, and gene expression. To examine the cellular mechanisms underlying the generation of circadian rhythms, nucleus-targeted and untargeted cDNAs encoding a Ca2+-sensitive fluorescent protein (cameleon) were transfected into organotypic cultures of mouse suprachiasmatic nucleus (SCN), the primary circadian pacemaker. Circadian rhythms in cytosolic but not nuclear Ca2+ concentration were observed in SCN neurons. The cytosolic Ca2+ rhythm period matched the circadian multiple-unit-activity (MUA)-rhythm period monitored using a multiple-electrode array, with a mean advance in phase of 4 hr. Tetrodotoxin blocked MUA, but not Ca2+ rhythms, while ryanodine damped both Ca2+ and MUA rhythms. These results demonstrate cytosolic Ca2+ rhythms regulated by the release of Ca2+ from ryanodine-sensitive stores in SCN neurons.

Original languageEnglish (US)
Pages (from-to)253-263
Number of pages11
Issue number2
StatePublished - Apr 24 2003

ASJC Scopus subject areas

  • General Neuroscience


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