Figure 3. The threshold voltage for keratinocyte galvanotaxis is decreased by hypoxic preconditioning.

Keratinocytes were pre-cultured in 2% O₂ or under normoxic conditions for 6 hours and then exposed to an EF of 25 mV/mm for another 3 hours under normoxic conditions. (A–F) Time-lapse photographs of keratinocyte migration guided by EF with (D–F) or without (A–C) hypoxic preconditioning. The red lines with blue arrowheads represent the trajectories and direction of cell movement. (G–H) Migration trajectories of cells over 3 hours with (H) or without (G) hypoxic preconditioning. (I–J) Analysis of the directedness or X-axis speed of keratinocyte migration. The data are from at least 100 cells in 3 independent experiments and are shown as the mean ± SEM. #, p < 0.01 compared with the cells without hypoxia pretreatment. Bar = 25 μm.