The biological effects of electric and magnetic fields. which are ubiquitous in modern society, remain poorly understood. Here, we applied a single-cell approach to study the effects of short-term exposure to extremely low frequency electromagnetic fields (ELF-EMFs) on muscle cell differentiation and function using C2C12 cells as an in vitro model of the skeletal muscle phenotype Our focus was on markers of oxidative stress and calcium (Ca(2+)) handling, two interrelated cellular processes previously shown to be affected by such radiation in other cell models Collectively, our data reveal that ELF-EMFs (1) induced reactive oxygen species production in myoblasts and myotubes with a concomitant decrease in mitochondrial membrane potential, (2) activated the cellular detoxification system, increasing catalase and glutathione peroxidase activities, and (3) altered intracellular Ca(2+) homeostasis, increasing the spontaneous activity of myotubes and enhancing cellular reactivity to a depolarizing agent (KCl) or ale agonist (caffeine) of anti acellular stole Ca(2+) channels in conclusion, our data support a possible link between exposure to ELF-EMFs and modification of the cellular redox state. which could. in turn. increase the level of intracellular Ca(2+) and thus modulate the metabolic activity of C2C12 cells. (C) 2009 Elsevier Inc All lights reserved.