A novel multi lines analysis tool of Ca dynamics reveals the nonuniformity of Ca propagation.

Extracellular stimuli evoke a robust increase in the concentration of intracellular Ca ([Ca]) throughout the cell to trigger various cellular responses, such as gene expression and apoptosis. This robust expansion of [Ca] is called Ca propagation. To date, it is thought that intracellular second messengers, such as inositol 1,4,5-trisphosphate (IP) and intracellular Ca, and clusters of IP receptors (IPRs) regulate Ca propagation. However, little is known about how the elevation in the [Ca] spreads throughout the cell, especially in non-polar cell, including HeLa cell. In this study, we developed a novel multi lines analysis tool. This tool revealed that the velocity of Ca propagation was inconstant throughout cell and local concentration of intracellular Ca did not contribute to the velocity of Ca propagation. Our results suggest that intracellular Ca propagation is not merely the result of diffusion of intracellular Ca, and that, on the contrary, intracellular Ca propagation seems to be regulated by more complicated processes.