Pulsed DC electric fields couple to natural NAD(P)H oscillations in HT-1080 fibrosarcoma cells

Previously, we have demonstrated that NAD(P)H levels in neutrophils and macrophages are oscillatory. We have also found that weak ultra low frequency AC or pulsed DC electric fields can resonate with, and increase the amplitude of, NAD(P)H oscillations in these cells. For these cells, increased NAD(P)H amplitudes directly signal changes in behavior in the absence of cytokines or chemotactic factors. Here, we have studied the effect of pulsed DC electric fields on HT-1080 fibrosarcoma cells. As in neutrophils and macrophages, NAD(P)H levels oscillate. We find that weak (approximately 10(-5) V/m), but properly phased DC (pulsed) electric fields, resonate with NAD(P)H oscillations in polarized and migratory, but not spherical, HT-1080 cells. In this instance, electric field resonance signals an increase in HT-1080 pericellular proteolytic activity. Electric field resonance also triggers an immediate increase in the production of reactive oxygen metabolites. Under resonance conditions, we find evidence of DNA damage in HT-1080 cells in as little as 5 minutes. Thus the ability of external electric fields to effect cell function and physiology by acting on NAD(P)H oscillations is not restricted to cells of the hematopoietic lineage, but may be a universal property of many, if not all polarized and migratory eukaryotic cells.