Cell-cycle-dependent changes in membrane potential of L-929 cells caused by the effect of hydrogen peroxide.

The changes in membrane potential of L-929 fibroblasts caused by H2O2 (10-50 microM) at different phases of the cell cycle were investigated. The membrane potential of cells in G0, early G1, and G2/M responded to H2O2 by hyperpolarizing, while cells in late G1/S responded by depolarizing. Quinidine (50 microM), a blocker of Ca2+-dependent K+ conductance, inhibited the hyperpolarization response of L-929 cells to H2O2 in all cases. Measurements of reactive oxygen species (ROS) production by the cells at the same cell cycle phases indicated that the hyperpolarization response of the cells is linked with minimal production of ROS, and that the depolarization response is associated with maximal production of ROS inside the cell.