Receptors, sparks and waves in a fire-diffuse-fire framework for calcium release

Coombes, Stephen and Hinch, Robert and Timofeeva, Yulia (2004) Receptors, sparks and waves in a fire-diffuse-fire framework for calcium release.

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Abstract

Calcium ions are an important second messenger in living cells. Indeed calcium signals in the form of waves have been the subject of much recent experimental interest. It is now well established that these waves are composed of elementary stochastic release events (calcium puffs or sparks) from spatially localised calcium stores. The aim of this paper is to analyse how the stochastic nature of individual receptors within these stores combines to create stochastic behaviour on long timescales that may ultimately lead to waves of activity in a spatially extended cell model. Techniques from asymptotic analysis and stochastic phase-plane analysis are used to show that a large cluster of receptor channels leads to a release probability with a sigmoidal dependence on calcium density. This release probability is incorporated into a computationally inexpensive model of calcium release based upon a stochastic generalization of the Fire-Diffuse-Fire (FDF) threshold model. Numerical simulations of the model in one and two dimensions (with stores arranged on both regular and disordered lattices) illustrate that stochastic calcium release leads to the spontaneous production of calcium sparks that may merge to form saltatory waves. Illustrations of spreading circular waves, spirals and more irregular waves are presented. Furthermore, receptor noise is shown to generate a form of array enhanced coherence resonance whereby all calcium stores release periodically and simultaneously.

Item Type: Article
Additional Information: To appear in Progress in Biophysics and Molecular Biology Special Issue: Modelling Cellular Function Animations connected with this paper can be found at http://masc-mac.lboro.ac.uk/~yulia/index.html
Uncontrolled Keywords: calcium sparks, ryanodine receptors, intracellular signalling, fire-diffuse-fire, stochastic transitions, calcium waves
Schools/Departments: University of Nottingham UK Campus > Faculty of Science > School of Mathematical Sciences
Depositing User: Coombes, Prof Stephen
Date Deposited: 17 Feb 2004
Last Modified: 27 Jun 2011 10:23
URI: http://eprints.nottingham.ac.uk/id/eprint/107

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