Figure 4

Cellular MDR1 distribution is modulated by electrical stimulation. a) The upper panel shows the immunocytochemical analysis of sub-cellular expression of MDR1. Note that prior to stimulation, MDR1 was primarily located in proximity of the plasma membrane. In stimulated cells, however, MDR immunosignal significantly shifted towards the center of the cell, suggesting a cytoplasmic or nuclear localization. Quantification was achieved by plotting the levels of expression against cell diameter; the dotted red lines show these relationships. Western blot analysis (lower panel) of sub-cellular fractions of cell types used for the experiments. Note that electrical stimulation caused a dramatic shift of membrane-bound MDR1 towards the cytosolic compartment. The numbers to the right show fold changes after electrical stimulation. b) Immunocytochemical analysis of MDR1 sub-cellular expression 48 hours post stimulation. Note that the effect of AC stimulation on MDR1 is reversible. Cells previously exposed to AC field demonstrating MDR1 cytosolic accumulation now replicates generating "normal" MDR1 + cells.