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Updated: Jun 22, 2026

Single-Cell Calcium Imaging for Studying the Activation of Calcium Ion Channels
Published on: December 13, 2024
Involvement of TRPC3 channels in calcium oscillations mediated by OX(1) orexin receptors
Hanna M Peltonen1, Johanna M Magga, Genevieve Bart
1A. I. Virtanen Institute for Molecular Sciences, Department of Neurobiology, University of Kuopio, POB 1627, FI-70211 Kuopio, Finland.
Abstract:
Oscillations of intracellular Ca2+ provide a novel mechanism for sustained activation of cellular processes. Receptor-activated oscillations are mainly thought to occur through rhythmic IP3-dependent store discharge. However, as shown here in HEK293 cells 1 nM orexin-A (Ox-A) acting at OX1 receptors (OX1R) triggered oscillatory Ca2+ responses, requiring external Ca2+. These responses were attenuated by interference with TRPC3 channel (but not TRPC1/4) function using dominant negative constructs, elevated Mg2+ (a blocker of many TRP channels) or inhibition of phospholipase A2. These treatments did not affect Ca2+ oscillations elicited by high concentrations of Ox-A (100 nM) in the absence of external Ca2+. OX1R are thus able to activate TRPC(3)-channel-dependent oscillatory responses independently of store discharge.
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