Directional protrusive pseudopodial activity and motility in macrophages induced by extracellular electric fields

Extracellularly applied electric fields (less than 12 V/cm) strongly influence murine resident peritoneal macrophages (M phi) to undergo directional protrusive pseudopodial activity towards the positive pole of the electric fields in the absence of exogenously applied chemotactic ligands. Internal and external morphological features were not grossly disrupted by the fields. Directional motility induced by the electric fields was inhibited in the presence of 1.0 mM La3+ or 2.5 mM Mg2+ and 5.0 mM EGTA. Effects of the fields were latent in the inhibited cells and directional motility was expressed after termination of the field and removal of the inhibitors. Receptors for the lectins concanavalin A (Con A) and phytohemagglutinin (PHA-L) were uniformly distributed on the surfaces of M phi with no exposure to electric fields. After exposure to the fields, Con A receptors were preferentially distributed on regions of the M phi surface facing the negative pole and PHA-L receptors were preferentially distributed on those regions facing the positive pole. The possibility that directional M phi motility is regulated by the molecular topography of the cell surface is discussed.