A MODEL FOR THE PROPAGATION OF INTERCELLULAR CALCIUM WAVES

In response to mechanical stimulation of a single cell, intercellular Ca2+ waves propagate through airway epithelial and glial cell cultures , providing a mechanism for intercellular communication. Experiments i ndicate that intercellular propagation of the Ca2+ wave is mediated by the movement of inositol 1,4,5-trisphosphate (IP3) through gap juncti ons. To explore the validity of this hypothesis, we have constructed a nd solved a system of partial differential equations that models the C a2+ changes induced by the movement of IP3 between cells. The model is in good qualitative agreement with experimental data, including the b ehavior of the wave in the absence of extracellular Ca2+, the shape of the subsequent asynchronous Ca2+ oscillations, and the passage of a w ave through a cell exhibiting Ca2+ oscillations. However, the concentr ation of IP3 that is required in each cell to propagate the wave may n ot be achieved by passive diffusion of IP3 through gap junctions from the stimulated cell. We therefore suggest that Ca2+-independent regene rative production of IP3 might be necessary for the propagation of int ercellular Ca2+ waves.