Recent developments in models of calcium signalling

The spatio-temporal behaviour of the intracellular calcium concentration is both physiologically important and theoretically complex, and this has led to a large body of joint experimental and theoretical work into the dynamics and physiology of calcium signalling. As new data become available, the older models undergo continual redevelopment, and many important questions remain. Here, we briefly discuss four areas in which new data have led to the development of new models, and new mathematical techniques. 1: Single-channel measurements of inositol trisphosphate receptors (IPR) showing that IPR exhibit modal behaviour, have led to the development of new hierarchical Markov models of IPR. 2: The observed stochastic behaviour of calcium spikes has led to a new family of stochastic models which are now just beginning to show how signals can contain information despite significant intercellular variability. 3: Recent data about the molecular mechanisms that connect endoplasmic reticulum calcium concentration to calcium influx have led to a greater understanding of how this influx controls calcium signalling. 4: It is becoming more apparent that complex interplay between calcium release and uptake to and from multiple organelles plays a major role in whole-cell calcium control, and this has stimulated the development of recent models that take multiple internal compartments into account.