Crosstalk between cellular morphology and calcium oscillation patterns. Insights from a stochastic computer model

Agonist-induced oscillations in the concentration of intracellular free calcium ([Ca²⁺](i)) display a wide variety of temporal and spatial patterns. In non-excitable cells, typical oscillatory patterns are somewhat cell-type specific and range from frequency-encoded, repetitive Ca²⁺ spikes to oscillations that are more sinusoidal in shape. Although the response of a cell population, even to the same stimulus, is often extremely heterogeneous, the response of the same cell to successive exposures can be remarkably similar. We propose that such 'Ca²⁺ fingerprints' can be a consequence of cell-specific morphological properties. The hypothesis is tested by means of a stochastic computer simulation of a two-dimensional model for oscillatory Ca²⁺ waves which encompasses the basic elements of the two-pool oscillator introduced by Goldbeter et al. In the framework of our extended spatiotemporal model, single cells can display various oscillation patterns which depend on the agonist dose, Ca²⁺ diffusibility, and several morphological parameters. These are, for example, size and shape of the cell and the cell nucleus, the amount and distribution of Ca²⁺ stores, and the subcellular location of the inositol(1,4,5)-trisphosphate-generating apparatus.