Electrochemical and electrical aspects of low-frequency electromagnetic current induction in biological systems

The use of electromagnetic current induction to modulate cell and tissue behavior via cell surface electrochemistry is considered in detail. It is shown that a strong correlation exists between electrochemical kinetic phenomena at cell surfaces, observable via transient impedance measurements, and the choice of induced current waveform parameters. In particular, the current pathway involving specific adsorption, such as that of Na⁺ or K⁺ at Na-K ATPase sites, appears to provide the strongest mechanistic correlation. Inductively coupled current signals can be constructed with the appropriate frequency content to excite this pathway. The actual electrical dosage appearing at the cellular level has been evaluated using air-gap Helmholtz coils. It is shown that Maxwell's equations, written for cylindrical geometry, accurately describe the spatial variation of current pulses in isotonic saline. An experimental technique for measurement of the induced electric field and current density vectors is described and applied to pure saline, a cell/saline complex, and muscle and bone tissue in vivo. The results obtained provide practical guidelines for the preferred coil/cell (tissue) orientations for the most uniform real-time dosage for cell culture, cell suspension, and in vivo situations.