Regensburg 2010 – scientific programme

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BP: Fachverband Biologische Physik

BP 15: Physics of Cells II

BP 15.2: Talk

Tuesday, March 23, 2010, 14:45–15:00, H43

Sensitisation waves in a bidomain fire-diffuse-fire model of intracellular Ca²⁺ dynamics — •Rüdiger Thul¹, Steven Coombes¹, and Greg D Smith² — ¹School of Mathematical Sciences, University of Nottingham, Nottingham, NG7 2RD, UK — ²Department of Applied Mathematics, The College of William and Mary, Williamsburg, VA 23187, USA

We present a bidomain threshold model of intracellular calcium (Ca²⁺ ) dynamics in which, as suggested by recent experiments, the cytosolic threshold for Ca²⁺ liberation is modulated by the Ca²⁺ concentration in the releasing compartment. We explicitly construct stationary fronts and determine their stability using an Evans function approach. Our results show that a biologically motivated choice of a dynamic threshold, as opposed to a constant threshold, can pin stationary fronts that would otherwise be unstable. This illustrates a novel mechanism to stabilise pinned interfaces in continuous excitable systems. Our framework also allows us to compute travelling pulse solutions in closed form and systematically probe the wave speed as a function of physiologically important parameters. We find that the existence of travelling wave solutions depends on the time scale of the threshold dynamics, and that facilitating release by lowering the cytosolic threshold increases the wave speed.