Figure 2.

Traces of Ca²⁺ (A,B) and Ba²⁺ (C,D) fluorescence change in CHO cells in response to a single 300-ns pulse at the indicated electric field strength (kV/cm). Images were taken every 10 s, and the pulse was delivered at 27 s into the experiment. Panels A and B show the same data at different vertical scales, to emphasize the statistically significant response already at 2.3 kV/cm (p < 0.01 compared to 0 kV/cm, two-tailed t-test) and its disproportional enhancement by the calcium-induced calcium release (CICR) once its threshold is exceeded (see text and [33] for more detail). Panel D uses the data from panel C to plot the fluorescence change per 10-s intervals between the sequential readings. The values were fitted with a double-exponential function (see text and [11] for detail). Mean +/− s.e., n = 30–45 cells for most groups.