Extremely Weak AC and DC Magnetic Fields Significantly Affect Myosin Phosphorylation

Abstract

Recent studies show that extremely low level electromagnetic fields (EMF) are capable of producing significant bioeffects. These effects have most often been related to the induced electric field, while the role of the magnetic component remains ambiguous. Most of the effects of weak magnetic fields have been studied by assuming that the cell membrane is the EMF target (Markov and Blank, 1988; Marino, 1988). In fact, the actual biophysical pathways involved in the coupling of weak electromagnetic fields to biological systems still remains unclear. The physical mechanisms which allow extremely low frequency and DC magnetic fields of milli- and microtesla intensity to interact with cells and to produce physiological and/or biochemical reactions is difficult to model. Nevertheless, a number of studies have recently been reported concerning the effects of weak magnetic and electromagnetic fields on calcium dependent processes and reactions. Several resonance mechanisms have been proposed by Chiabrera et al., 1985; Liboff,1985; Lednev, 1991; and Chiabrera et al., 1991. They are related to the Lorentz force effects on ion transport (cyclotron resonance) or on ion/ligand binding kinetics. Recently, a quantum approach was taken which suggests that the ion movement in a binding site is quantitized, leading to parametric resonance. It has been reported that weak AC/DC fields tuned to calcium frequencies can significantly affect Ca²⁺/calmodulin dependent myosin phosphorylation (Shuvalova et al., 1991). Myosin light chains are known to be capable of binding divalent cations and are phosphorylated by myosin light-chain kinase, which requires calmodulin, a calcium binding protein, to function.