Bruce R. McLeod

Experimental Evidence for Ion Cyclotron Resonance Mediation of Membrane Transport

There is now a rich history to those experiments studying the stimulation of biological systems using extremely weak electrical and magnetic fields. In the following, we review this work, with particular emphasis on the experimental evidence in support of ion cyclotron resonance as the interaction mechanism underlying the observed effects. The number of compartmentalized groups studying electromagnetic effects in tissue is growing rapidly, and it is wise to limit the area we shall cover. Thus, we restrict ourselves solely to those observations involving time-varying fields, primarily in the ELF range. We will begin with a short review of ion cyclotron resonance.

Effects of CR-tuned 60 Hz magnetic fields on sprouting and early growth of Raphanus sativus

Abstract We exposed seeds of Raphanus sativus to 60 Hz ELF fields tuned to the ion cyclotron resonance frequencies for calcium and potassium ions. Exposure lasted for 24 h/day for 21 days. Controls consisted of non-exposed seeds and seeds exposed to 60 Hz fields with a static component of zero. The seeds exposed to calcium-tuned fields were slow to germinate, but grew more rapidly and were finally larger than the controls. Exposure to potassium-tuned fields produced rapid germination, but mildly inhibited further growth, except for the roots which were larger than those of the controls. We regard the results with calcium as typical of the general growth-stimulating role for this ion. The same is true for the generally inhibitory role of potassium, except for plant roots where potassium is a known stimulatory factor.

Electromagnetic gating in ion channels

There have been many attempts to develop a theoretical explanation of the phenomena of electromagnetic field interactions with biological systems. None of the reported efforts have been entirely successful in accounting for the observed experimental results, in particular with respect to the reports of interactions between extremely low frequency (ELF) magnetic fields and biological systems at ion cyclotron resonance frequencies. The approach used in this paper starts with the Lorentz force equation, but use is made of cylindrical co-ordinates and cylindrical boundary conditions in an attempt to more closely model the walls of an ion channel. The equations of motion of an ion that result from this approach suggest that the inside shape of the channel plus the ELF magnetic fields at specific frequencies and amplitudes could act as a gate to control the movement of the ion across the cell membrane.

Calcium and Potassium Cyclotron Resonance Curves and Harmonics in Diatoms (A. Coeffeaformis)

Our previous findings provide strong evidence that transport of a given ionic species through a cell membrane can be precisely controlled by tuning externally applied magnetic fields to the ion cyclotron resonance (CR) gyrofrequency for the ion in question. Experiment and theory have shown that certain odd harmonics of the fundamental resonance frequency are also effective. In the present experiment we again used the model of Ca-dependent motility of benthic diatoms, extending our harmonic studies through N = 17, for both Ca2+ and K+ fundamentals. Eight separate Ca2+ fundamental frequencies: 8, 12, 16, 23, 31, 32, 46, 64 Hz were attempted and each was found to obey the CR condition. We also report two observations: (1) tuning to K+ results in inhibition of motility, directly opposite to the enhancement that occurs when tuning for Ca2+; (2) both the K+ inhibition and Ca2+ enhancement are independently observed at exactly the same harmonics: N = 1, 3, 5, 15. This strongly suggests that despite differences i...

Nifedipine is an antagonist to cyclotron resonance enhancement of 45Ca incorporation in human lymphocytes

The incorporation of 45Ca in mixed human lymphocytes was measured following one-hour exposures of the cells to combined steady and periodic magnetic fields designed to probe for cyclotron resonance response in calcium incorporation. Measurements were made as a function of magnetic field frequency, up to 30 Hz, and as a function of magnetic field amplitude, up to 1.5 x 10(-4) Trms. The amplitude measurements demonstrated that the relative 45Ca uptake at resonance follows different mechanisms of interaction above and below 0.2 x 10(-4) Trms. After adjusting the magnetic field configuration for maximum incorporation, we then determined the effects of the calcium influx blocker nifedipine on 45Ca incorporation, with and without simultaneous exposure to this specific magnetic field combination. The presence of nifedipine in both unexposed and exposed cell suspensions resulted in decreased 45Ca uptake, presumably through the slow inward calcium channels. Evidence was found suggesting that nifedipine acts antagonistically to the 45Ca cyclotron resonance tuning signal.

Biological Systems in Transition: Sensitivity to Extremely Low-Frequency Fields

It has been suggested for some time that cells “far from equilibrium” may be the most sensitive to applied extremely low-frequency (ELF) electric and magnetic fields. The problem with this statement is that it is nearly impossible to quantify these words as they apply to a biological system in such a way that the definition can become part of a mechanistic model. It is apparent, however, that the physiological state of the biological system being exposed to ELF fields is important. A review of the literature allows one to identify many studies that have involved the simultaneous exposure of “normal” and “healing” cells to ELF fields (such as normal bone and flesh at a non-union fracture site), with the result being that only the “healing” cells were measurably affected by the applied fields. The nonunion fracture in bone may be one example of where the state of the biological system (bone) can be quantified. It is also apparent that the physiological state of the system must be important in the ELF-biolog...

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 Maxwells 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 tissuein 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, andin vivo situations.

Cyclotron Resonance in Cell Membranes: The Theory of the Mechanism

The search for mechanisms to explain electromagnetic (EM) field interactions with living systems was concentrated almost entirely in studies of electric fields in and the dielectric properties of the living systems prior to 1984. Magnetic fields had been studied as a prime mover, but primarily only high level magnetic fields such as one might find in the power generation industry or near superconducting magnetics had been considered. Any effects of very low level magnetic fields were assumed to be small enough to be ignored since living systems are primarily dielectric, not magnetic (from a material property viewpoint). The flaw in this reasoning is that a non-time varying (dc) magnetic field combined with a carefully chosen electric field can possibly alter the way in which a dielectric material responds to the electric field.

Direct Electric Current Treatment under Physiologic Saline Conditions Kills Staphylococcus epidermidis Biofilms via Electrolytic Generation of Hypochlorous Acid

The purpose of this study was to investigate the mechanism by which a direct electrical current reduced the viability of Staphylococcus epidermidis biofilms in conjunction with ciprofloxacin at physiologic saline conditions meant to approximate those in an infected artificial joint. Biofilms grown in CDC biofilm reactors were exposed to current for 24 hours in 1/10th strength tryptic soy broth containing 9 g/L total NaCl. Dose-dependent log reductions up to 6.7 log10 CFU/cm2 were observed with the application of direct current at all four levels (0.7 to 1.8 mA/cm2) both in the presence and absence of ciprofloxacin. There were no significant differences in log reductions for wells with ciprofloxacin compared to those without at the same current levels. When current exposures were repeated without biofilm or organics in the medium, significant generation of free chlorine was measured. Free chlorine doses equivalent to the 24 hour endpoint concentration for each current level were shown to mimic killing achieved by current application. Current exposure (1.8 mA/cm2) in medium lacking chloride and amended with sulfate, nitrate, or phosphate as alternative electrolytes produced diminished kills of 3, 2, and 0 log reduction, respectively. Direct current also killed Pseudomonas aeruginosa biofilms when NaCl was present. Together these results indicate that electrolysis reactions generating hypochlorous acid from chloride are likely a main contributor to the efficacy of direct current application. A physiologically relevant NaCl concentration is thus a critical parameter in experimental design if direct current is to be investigated for in vivo medical applications.

PEMF, Direct Current and Nedronal Regeneration: Effect of Field Geometry and Current Density

Sensory ganglia from 7-8 day chick embryos were exposed to pulsed electromagnetic fields (PEMF) or direct current(DC) in order to correlate stimulation of neurite outgrowth with current density as a function of field geometry. Growth scores were obtained on ganglia growing in the inner and outer rings of 50 mm culture dishes. Control cultures and cultures treated with nerve growth factor served as standards. In PEMF experiments with the coil pair oriented horizontally, no correlation was observed between ganglia growth and current density in contrast to our previous findings with the coils oriented vertically. Comparison of current density for vertical and horizontal coils driven identically suggests a dose-saturation effect for the induced current with a threshold at approximately 0.4 uA/cm2. Application of DC elicited significantly greater growth as a function of location with current density levels above 9 nA/cm2. Interestingly, the total charge input for PEMF and DC stimulation was nearly identical, 1...