Andrew B. Gapeyev, Elena N. Mikhailik, and Nikolay K. Chemeris
Institute of Cell Biophysics of Russian Academy of Sciences, Pushchino, Moscow Region, Russia
Summary of research published in Bioelectromagnetics, Vol. 30, No. 6, pp. 454-461.
Under typical environmental conditions, open and self-organizing biological systems are exposed to a wide spectrum of multiple-frequency and modulated electromagnetic fields (EMFs). We observed that there is no information in the literature about mechanisms describing the reaction of biological systems to multiple-frequency electromagnetic exposure on the background of increasing pharmacological load. In typical experiments, features and regularities of biological effects of modulated EMFs are not accurately defined, despite the fact that the existence of modulation can lead to significant changes in biological effect patterns compared to the effects of continuous radiation with the same carrier frequencies. Physical and chemical mechanisms of biological effects of modulated and continuous electromagnetic fields can be different and are probably connected to the influence on quasi-periodic processes that dominate in formation, stability, development, and functioning of all living systems. We considered that studying modulated EMF could be done by subjecting the object simultaneously to a set of harmonic signals. By selecting type and frequencies of modulation we may be able to differentially influence particular systems of a cell or an organism.
Earlier, using various cellular models in vitro, we showed that pulse-modulated, extremely high-frequency electromagnetic radiation (EHF EMR) can essentially modify cellular functions, with the effects being critically dependent on combination of carrier and modulation frequencies. Modulated EHF EMR (42.2±0.2 GHz, incident power density of 0.1 mW/cm2, modulation frequency of 0.095±0.005 Hz) inhibited a motor activity of unicellular protozoa Paramecium caudatum [Gapeyev et al., 1994]. The effect was named a "double resonance", as it had a quasi-resonance dependence on both carrier and modulation frequencies, and was not observed under the influence of continuous EHF EMR. Modulated EHF EMR (41.95 GHz, 0.05 mW/cm2, 20-min exposure duration) inhibited or activated the production of reactive oxygen species by isolated peritoneal neutrophils of mice depending on modulation frequencies [Gapeyev et al., 1998]. We suggested that calcium-dependent intracellular signal transduction pathways activated at neutrophils' respiratory burst are selective to both carrier and modulation frequencies of EHF EMR.
The present study was performed to determine features of biological effects of low-intensity modulated EHF EMR using a model of acute non-specific inflammation in laboratory mice of NMRI outbreed stock. Our recent data showed that the model of acute zymosan-induced paw edema in mice is very sensitive to the influence of low-intensity EHF EMR. Single whole-body exposure of animals to continuous EHF EMR for 20 min reduced the exudative edema of inflamed paw on average by 20% compared to the control at intensities of 0.1-0.7 mW/cm2 and frequencies from the range of 42.2-42.6 GHz [Gapeyev et al., 2008]. We have now demonstrated that application of different modulation frequencies from the range of 0.03-100 Hz did not lead to considerable changes in the effect level caused by effective carrier frequency of 42.2 GHz. When specific combinations of "ineffective" carrier frequencies of 43.0 and 61.22 GHz, and modulation frequencies of 0.07-0.1 and 20-30 Hz were applied, the anti-inflammatory effect showed synergistic enhancement in narrow ranges of modulation frequencies.
Considering an increasing level of anthropogenic complex-modulated EMF, the results we obtained showing synergistic enhancement of EHF EMR effects at the certain combination of carrier and modulation frequencies have special importance. In narrow bands of modulation frequencies, certain carrier frequencies become biologically active, which by themselves did not previously cause appreciable biological action. This could mean that in a real environment of biological systems, considering the nonlinear interaction of inherent oscillation modes, there can be the combination of frequencies selectively influencing certain systems of cells and an organism as a whole. The efficacy and direction of such action is ambiguous, as it strongly depends on the functional status of a biological object that can be changed by application of various pharmacological treatments. In some cases, there are additive and synergistic effects that strengthen the action of medical drugs [Gapeyev et al., 2008]. This has undoubted potential advantage for clinical application through possibly lowering a dosage of applied drugs to reduce their side effects. It is obvious that the further detailed studies are necessary for the purpose of determining key molecular and cellular mechanisms responsible for realization of effects of multiple-frequency and modulated EMFs.
The work was supported by the Russian Foundation for Basic Research (project # 08-04-90000) and the Russian Science Support Foundation.