Mean field strategies induce unrealistic nonlinearities in calcium puffs

GUILLERMO SOLOVEY; DANIEL E. FRAIMAN BORRAZAS; SILVINA PONCE DAWSON

Frontiers in Computational Physiology and Medicine

Frontiers

Año: 2011 vol. 2 p. 4601 - 4611

1664-042X

Mean field models are often useful approximations to biological systems, but sometimes, they can yield misleading results. In this work, we compare mean field approaches with stochastic models of intracellular calcium release. In particular, we concentrate on calcium signals generated by the concerted opening of several clustered channels (calcium puffs). To this end we simulate calcium puffs numerically and then try to reproduce features of the resulting calcium distribution using mean field models were all the channels open and close simultaneously. We show that an unrealistic nonlinear relationship between the current and the number of open channels is needed to reproduce the simulated puffs.  Furthermore, a single channel current which is five times smaller than the one of the stochastic simulations is also needed.  Our study sheds light on the importance of the stochastic kinetics of the calcium release channel activity to estimate the release fluxes.