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AKB: Biologische Physik

AKB 40: Poster Session II

AKB 40.37: Poster

Mittwoch, 29. März 2006, 16:30–19:30, P3

Approximation of localised calcium fluxes — •Kajetan Bentele and Martin Falcke — Hahn Meitner Institut Berlin, Glienickerstrasse 100, 14109 Berlin, Germany

To model spatially resolved intracellular calcium-dynamics, it is necessary to investigate the calcium current through a single channel. An open channel can be modelled as a pore connecting an intracellular calcium store, the endoplasmic reticulum (ER), with the cytosol. The radius of such a channel is about 6 nanometres in contrast to the diameter of the cell ranging from 10 to 100 micrometres. Opening of such a channel leads to a localised increase of the cytosolic calcium concentration nearby the channel. This process is the fundamental building block in the concentration dynamics of global events such as calcium waves and oscillations.

We present a quasi-steady state approximation of the single-channel current with a simplified dynamics. The approximation is based on the observation that the channel current exhibits multiple time scales: infinitely many fast time scales and a long time-scale that can be up to 5 orders of magnitude larger. The former play a prominent role in building up the concentration-peak around the channel. The slow time scale is determined by the average concentration in the ER and therefore can be mimicked by a quasi steady state approximation. This approximation will be used in simulations to eliminate spatial dynamics in the ER.