Applied Mathematics Seminar

Fire-Diffuse-Fire (FDF) calcium waves are observed in a number of different types of cells and are characterised by a process of regenerative release and diffusion of calcium that lurches between adjacent release sites inside the cell. In this talk results will be given of a theoretical investigation of FDF calcium waves propagating through a three dimensional rectangular domain. The domain is infinite in extent in the direction of propagation but with lateral barriers to diffusion which contain calcium pumps. The calcium concentration profile due to the firing of a release site (spark) is derived analytically based on the Green's function for the diffusion equation on the domain. The existence, stability and speed of these waves is shown to be critically dependent on the dimensions of the domain and the calcium pump rate. It is shown that the smaller the dimensions of the region, the lower the calcium release flux required for wave propagation, and the higher the wave speed. Also it is shown that the region may support multiple calcium wave fronts of varying wave speed. This model is relevant to subsarcolemmal waves in atrial myocytes (Kockskämper et al, 2001, Biophys. J. 81, 2590-2605), and the results may be of importance in understanding the roles of the endoplasmic/sarcoplasmic reticulum, surface membranes and calcium pumps in the intracellular calcium dynamics of cells.