A mesoscopic stochastic mechanism of cytosolic calcium oscillations

Based on a model of intracellular calcium (Ca2+) oscillation with self-modulation of inositol 1,4,5-trisphosphate signal, the mesoscopic stochastic differential equations for the intracellular Ca2+ oscillations are theoretically derived by using the chemical Langevin equation method. The effects of the finite biochemical reaction molecule number on both simple and complex cytosolic Ca2+ oscillations are numerically studied. In the case of simple intracellular Ca2+ oscillation, it is found that, with the increase of molecule number, the coherence resonance or autonomous resonance phenomena can occur for some external stimulation parameter values. In the cases of complex cytosolic Ca2+ oscillations, each extremum of concentration of cytosolic Ca2+ oscillations corresponds to a peak in the histogram of Ca2+ concentration, and the most probability appeared during the bursting plateau level for bursting, but at the largest minimum of Ca2+ concentration for chaos. For quasi-periodicity, however, there are only two peaks in the histogram of Ca2+ concentration, and the most probability is located at low concentration state.