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BP: Fachverband Biologische Physik

BP 9: Regulation and Signaling

BP 9.7: Vortrag

Dienstag, 27. März 2007, 11:45–12:00, H43

Hybrid models and simulations of intracellular calcium dynamics — •Sten Rüdiger — Hahn-Meitner-Institut, Glienicker Str. 100, 14109 Berlin

Intracellular calcium release is a prime example for the role of stochastic effects in cellular systems. Recent models consist of deterministic reaction-diffusion equations coupled to stochastic transitions of calcium channels. The resulting dynamics is of multiple time and spatial scales, which complicates far-reaching computer simulations. In this contribution we introduce a novel hybrid scheme that is especially tailored to accurately trace events with essential stochastic variations, while deterministic concentration variables are efficiently and accurately traced at the same time. We use finite elements to efficiently resolve the extreme spatial gradients of concentration variables close to a channel. We describe the algorithmic approach and we demonstrate its efficiency compared to conventional methods. Our single channel model matches experimental data by Mak et al. (PNAS 95, 15821, 1998) and results in intriguing dynamics if calcium is used as charge carrier. Random openings of the channel accumulate in bursts of calcium blips that may be central for the understanding of cellular calcium dynamics. We further discuss calcium release from clusters of channels and and the effects of calcium-binding proteins on the dynamics.