Hysteresis and bistability in a realistic model for IP3-driven Ca2+ oscillations

We present a new model for inositol triphosphate (IP3)-induced cytosolic Ca2+ oscillations in non-excitable cells. The model includes the various Ca2+ in- and efflux pathways reported to exist in these cells. In particular, it features the complex regulation of the Ca2+ release from the endoplasmic reticulum (ER) by IP3, cytosolic Ca2+ and Ca2+ in the ER. Bifurcation analysis revealed that the model accurately predicts the cytosolic Ca2+ dynamics in a typical non-excitable cell. Diffusional coupling of this model in a two-dimensional network shows hysteresis and bistability in its collective dynamics. Depending on the strength of the diffusion constant, we find traveling or spiral waves as solutions of this system.