How does intracellular Ca2+ oscillate: by chance or by the clock?
Alexander Skupin 1, Helmut Kettenmann 2, Ulrike Winkler 2, Maria Wartenberg 3, Heinrich Sauer 4, Steven C. Tovey 5, Colin W. Taylor 5 and Martin Falcke 6*
1 Hahn Meitner Institute
2 Max Delbruck Center for Molecular Medicine
3 University Jena
4 University Giessen
5 University of Cambridge
6 Hahn-Meitner-Institute
* To whom correspondence should be addressed. E-mail: falcke{at}hmi.de.
Submitted on August 9, 2007
Revised on September 26, 2007
Accepted on 9 November 2007
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Abstract |
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Ca2+ oscillations have been considered to obey deterministic dynamics for almost two decades. We show for four cell types that Ca2+ oscillations are instead a sequence of random spikes. The standard deviation of the interspike intervals (ISI) of individual spike trains is similar to the average ISI; it increases approximately linearly with the average ISI; and consecutive ISI are uncorrelated. Decreasing the effective diffusion coefficient of free Ca2+ using Ca2+ buffers increases the average ISI and the standard deviation in agreement with the idea that individual spikes are caused by random wave nucleation. Array enhanced coherence resonance (AECR) leads to regular Ca2+ oscillations with small standard deviation of ISI.
Key Words:
calcium signalling, cell signalling, ion channels, modelling and systems biology, noise in biological systems
