Cytosolic calcium oscillators: Critical discussion and stochastic modelling

In the last few years, an immense amount of experimental data on agonist-induced cytosolic Ca²⁺ oscillations has emphasized the necessity of theoretical models accounting for these phenomena. In the first part of the paper, a critical analysis of different minimal Ca²⁺ oscillator models is presented, which reveals that not all of the so far proposed mechanisms are capable to reproduce experimental data adequately. The second part of the paper is devoted to a computational method using a stochastic simulation algorithm which describes the time evolution of Ca²⁺ oscillations at the molecular level. In contrast to the deterministic formulation of the models presented so far, the stochastic treatment takes account of the inherent fluctuations of cytosolic Ca²⁺ in cellular subcompartments. In the macroscopic limit, the stochastic models display dynamics analogous to the deterministic ones.