Figure 1.

Schematics of experimental setup. (A) Top and cross views of the microfluidics device for delivering ATP solution to cultured fibroblast (NIH 3T3) cells. Inset: Fluorescent calcium imaging of a typical experiment. (B) Relative fluorescent intensities indicating the calcium dynamics, $R_i\left(t\right)$, of individual cells (dashed lines) when stimulated by external ATP at four different concentrations, and the average trajectories (solid lines) at each concentration. To see this figure in color, go online.