Role of intracellular Na+ in the regulation of [Ca2+]i in the rat suprachiasmatic nucleus neurons

Ruo Ciao Cheng, Pi Cheng Cheng, Yi Chi Wang, Rong Chi Huang*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

5 Scopus citations


Transmembrane Ca2+ influx is essential to the proper functioning of the central clock in the suprachiasmatic nucleus (SCN). In the rat SCN neurons, the clearance of somatic Ca2+ following depolarization-induced Ca2+ transients involves Ca2+ extrusion via Na+/Ca2+ exchanger (NCX) and mitochondrial Ca2+ buffering. Here we show an important role of intracellular Na+ in the regulation of [Ca2+]i in these neurons. The effect of Na+ loading on [Ca2+]i was determined with the Na+ ionophore monensin and the cardiac glycoside ouabain to block Na+/K+-ATPase (NKA). Ratiometric Na+ and Ca2+ imaging was used to measure the change in [Na+]i and [Ca2+]i, and cell-attached recordings to investigate the effects of monensin and ouabain on spontaneous firing. Our results show that in spite of opposite effects on spontaneous firing and basal [Ca2+], both monensin and ouabain induced Na+ loading, and increased the peak amplitude, slowed the fast decay rate, and enhanced the slow decay phase of 20 mM K+-evoked Ca2+ transients. Furthermore, both ouabain and monensin preferentially enhanced nimodipine-insensitive Ca2+ transients. Together, our results indicate that in the SCN neurons the NKA plays an important role in regulating [Ca2+]i, in particular, associated with nimodipine-insensitive Ca2+ channels.

Original languageEnglish
Article number4868
JournalInternational Journal of Molecular Sciences
Issue number19
StatePublished - 01 10 2019

Bibliographical note

Publisher Copyright:
© 2019 by the authors. Licensee MDPI, Basel, Switzerland.


  • Ca
  • Mitochondria
  • Na
  • Na/Ca exchanger
  • Na/K-ATPase
  • Suprachiasmatic nucleus


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