Fig. 4. A direct-current EF induces [Ca²⁺]_i elevation from the control and later-appearing [Ca²⁺]_i spikes. (A-J) Fluorescent images of Fluo-3-AM-loaded cells. (A,B) Entire field at time 0 and 240 seconds. The EF was switched on immediately after the frame in A was taken and the cells moved to the right (towards the cathode). (C-J) Selected field showing details of migrating cells and the [Ca²⁺]_i spikes (E,I). (K) Tracks of the three cells shown in A-J. (L) EF exposure significantly increases [Ca²⁺]_i (P=8^–9), which is prevented in the presence of 5 mM EGTA (n=29-30 cells; supplementary material Movie 2). Numbers in A and C indicate individual cells.