CALCIUM WAVES IN A MODEL WITH A RANDOM SPATIALLY DISCRETE DISTRIBUTION OF CA2+ RELEASE SITES

We study the propagation of intracellular calcium waves in a model tha t features Ca2+ release from discrete sites in the endoplasmic reticul um membrane and random spatial distribution of these sites. The result s of our simulations qualitatively reproduce the experimentally observ ed behavior of the waves. When the lever of the channel activator inos itol trisphosphate is low, the wave undergoes fragmentation and eventu ally vanishes at a finite distance from the region of initiation, a ph enomenon we refer to as an abortive wave. With increasing activator co ncentration, the mean distance of propagation increases. Above a criti cal level of activator, the wave becomes stable. We show that the hete rogeneous distribution of Ca2+ channels is the cause of this phenomeno n.