The spatial arrangements of stochastic Ca 2+ signals triggered by IP3 release

Clusters of IP3 receptor channels in the membranes of the endoplasmic reticulum (ER) of many non-excitable cells release calcium ions in a cooperative manner giving rise to dynamical patterns such as Ca2+ puffs, waves and oscillations that occur on various spatial and temporal scales. We introduce a stochastic reaction-diffusion model of randomly distributed IP3 receptors using a principled reduction of a detailed Markov chain description of individual channels. Our model reveals how the crucial characteristic of cell regulation such as inter-wave intervals (IWI) depends on the IP3 loads. Furthermore, by performing a correlation analysis of the [Ca2+] at the neighbouring clusters, we obtain the principal characteristics of the membrane which define the possibility of Ca2+ wave initiation and propagation. Using given approach, we aim to link the local properties of IP3R channels and clusters, such as channel type or coupling between channels, with the global patterns which may emerge from these channels, e. g. spikes, waves or oscillations