Effect of Electromagnetic Fields on Two Calcium Dependent Biological Systems

A review on the effects of extremely low frequency electromagnetic field (ELF-EMF) on cytokines of innate and adaptive immunity

Extremely low frequency electromagnetic field (ELF-EMF) is produced extensively in modern technologies. Numerous in vitro and in vivo studies have shown that ELF-EMF has both stimulatory and inhibitory effects on the immune system response. This review was conducted on effects of ELF-EMF on cytokines of innate and adaptive immunity. Mechanisms of ELF-EMF, which may modulate immune cell responses, were also studied. Physical and biological parameters of ELF-EMF can interact with each other to create beneficial or harmful effect on the immune cell responses by interfering with the inflammatory or anti-inflammatory cytokines. According to the studies, it is supposed that short-term (2-24 h/d up to a week) exposure of ELF-EMF with strong density may increase innate immune response due to an increase of innate immunity cytokines. Furthermore, long-term (2-24 h/d up to 8 years) exposure to low-density ELF-EMF may cause a decrease in adaptive immune response, especially in T_h1 subset.

Extremely Low-Frequency Pulsed Magnetic Fields and Multiple Sclerosis: Effects on Neurotransmission Alone or Also on Immunomodulation? Building a Working Hypothesis

This paper outlines the current state of knowledge on the pathology and treatment of multiple sclerosis (MS) and critically analyses the vast clinical experience of Sandyk in the use of pulsed magnetic fields of 5 Hz at 7.5 pT to treat many symptoms of MS. A complete regression of symptoms, or at least a major improvement, is sometimes so rapid as to suggest that ELF fields exert a greater effect on axonal and synaptic neurotransmission than on the processes leading to demyelination. Pulsed magnetic fields of 50–100 Hz and a few mT (whose flux intensity is 109 times greater than that of the fields used by Sandyk) have been seen to induce profound morphological changes (the Marinozzi effect) in the plasma membrane of several cell types, including Raji human lymphoblastoid cells. These observations underlie the author's hypothesis on the possible use of such fields in the treatment of MS. Indeed, these fields should induce the functional arrest of the cells (B- and T-lymphocytes, macrophages, microglia, dendritic cells) of the MS plaque, thereby providing an ‘electromagnetic immunomodulatory boost’ to the effects of drug therapy. To test this working hypothesis, it is suggested that preliminary experimental research be carried out to ascertain: 1) the Marinozzi effect in vivo; 2) the Marinozzi effect on microglia and dendritic cells; and 3) the duration of the membrane changes and their relaxation rate. ELF magnetic fields in the picotesla and millitesla ranges are aimed at improving neurotransmission and correcting local immune pathology, respectively. Both types of field might find application in the treatment of MS patients who no longer respond to or tolerate currently used drugs.

Enhancing Effect of Electromagnetic Exposure on Calciumionophore (A23187), but Not IL-1, Induced Txa2 Release by Human Neutrophils

The exposure of human polymorphonuclears to an extremely low frequency (3 Hz) electromagnetic field for 1 hour had an enhancing effect on thromboxane A2 release stimulated by A23187 calcium ionophore. On the contrary, IL-1 stimulation of TxA2 production was not affected by an electromagnetic field, suggesting that interleukin-1 influence on thromboxane synthesis is not due to a calcium ionophore-like action.

Extremely low frequency electromagnetic fields stimulation modulates autoimmunity and immune responses: a possible immuno-modulatory therapeutic effect in neurodegenerative diseases

Increasing evidence shows that extremely low frequency electromagnetic fields (ELF-EMFs) stimulation is able to exert a certain action on autoimmunity and immune cells. In the past, the efficacy of pulsed ELF-EMFs in alleviating the symptoms and the progression of multiple sclerosis has been supported through their action on neurotransmission and on the autoimmune mechanisms responsible for demyelination. Regarding the immune system, ELF-EMF exposure contributes to a general activation of macrophages, resulting in changes of autoimmunity and several immunological reactions, such as increased reactive oxygen species-formation, enhanced phagocytic activity and increased production of chemokines. Transcranial electromagnetic brain stimulation is a non-invasive novel technique used recently to treat different neurodegenerative disorders, in particular Alzheimer's disease. Despite its proven value, the mechanisms through which EMF brain-stimulation exerts its beneficial action on neuronal function remains unclear. Recent studies have shown that its beneficial effects may be due to a neuroprotective effect on oxidative cell damage. On the basis of in vitro and clinical studies on brain activity, modulation by ELF-EMFs could possibly counteract the aberrant pro-inflammatory responses present in neurodegenerative disorders reducing their severity and their onset. The objective of this review is to provide a systematic overview of the published literature on EMFs and outline the most promising effects of ELF-EMFs in developing treatments of neurodegenerative disorders. In this regard, we review data supporting the role of ELF-EMF in generating immune-modulatory responses, neuromodulation, and potential neuroprotective benefits. Nonetheless, we reckon that the underlying mechanisms of interaction between EMF and the immune system are still to be completely understood and need further studies at a molecular level.

Effect of 100 mT homogeneous static magnetic field on [Ca2+]c response to ATP in HL-60 cells following GSH depletion

Calcium is an important molecule in a number of biological systems. Often these systems are signal transduction cascades involving molecules such as ATP. ATP activates second messengers which can interact with ion channels on the endoplasmic/sarcoplasmic reticulum resulting in the emptying of the intracellular calcium stores and an increase in cytosolic free calcium concentration ([Ca2+]c). Changes in [Ca2+]c can be influenced by external factors such as a static magnetic field (SMF). One hypothesis suggests that a SMF affects the cells through the radical pair mechanism. By reducing the number of antioxidant molecules like glutathione (GSH), the proportion of free radicals in the cells is increased and may lead to a greater probability of a biological response to a SMF. The purpose of this study was to determine if the [Ca2+]c response to ATP was affected by depletion of GSH by diethylmaleate (DEM) and the absence or presence of a 100 mT homogeneous SMF. Undifferentiated HL-60 cells were loaded with fura-2 AM. [Ca2+]c was measured in real time using a ratiometric fluorescence spectroscopy system. Various (DEM) ranging from 1 to 15 mM were added to deplete GSH. Cells were either exposed to sham or magnetic field (100 mT) for 13 min (780 s) and challenged with 1 microM ATP. The data show that [Ca2+]c was elevated following treatment with DEM with greater [Ca2+]c at higher [DEM]. The [Ca2+]c response to ATP was decreased as the DEM concentration increased. However, there was no effect of a 100 mT SMF on the average [Ca2+]c peak following ATP activation or the full width at half maximum (FWHM) of the [Ca2+]c response and recovery after ATP activation.

Modulation of MCP-1 and iNOS by 50-Hz sinusoidal electromagnetic field

The purpose of this study was to investigate whether overnight exposure to 1 mT-50 Hz extremely low-frequency sinusoidal electromagnetic field (EMF) affects the expression and production of inducible nitric oxide synthase (iNOS) and monocyte chemotactic protein-1 (MCP-1) in human monocytes. RT-PCR and Western blot analysis demonstrate that EMF exposure affects the expression of iNOS and MCP-1 in cultured human mononuclear cells at the mRNA level and protein synthesis. Interestingly, the effects of EMF exposure clearly differed with respect to the potentiation and inhibition of iNOS and MCP-1 expression. Whereas iNOS was down-regulated both at the mRNA level and at the protein level, MCP-1 was up-regulated. These results provide helpful information regarding the EMF-mediated modulation of the inflammatory response in vivo. However, additional studies are necessary to demonstrate that EMF acts as a nonpharmacological inhibitor of NO and inducer of MCP-1 in some diseases where the balance of MCP-1 and NO may be important.

Influence of 1 and 25 Hz, 1.5 mT magnetic fields on antitumor drug potency in a human adenocarcinoma cell line

The resistance of tumor cells to antineoplastic agents is a major obstacle during cancer chemotherapy. Many authors have observed that some exposure protocols to pulsed electromagnetic fields (PEMF) can alter the efficacy of anticancer drugs; nevertheless, the observations are not clear. We have evaluated whether a group of PEMF pulses (1.5 mT peak, repeated at 1 and 25 Hz) produces alterations of drug potency on a multidrug resistant human colon adenocarcinoma (HCA) cell line, HCA-2/1(cch). The experiments were performed including (a) exposures to drug and PEMF exposure for 1 h at the same time, (b) drug exposure for 1 h, and then exposure to PEMF for the next 2 days (2 h/day). Drugs used were vincristine (VCR), mitomycin C (MMC), and cisplatin. Cell viability was measured by the neutral red stain cytotoxicity test. The results obtained were: (a) The 1 Hz PEMF increased VCR cytotoxicity (P < 0.01), exhibiting 6.1% of survival at 47.5 microg/ml, the highest dose for which sham exposed groups showed a 19.8% of survival. For MMC at 47.5 microg/ml, the % of survival changed significantly from 19.2% in sham exposed groups to 5.3% using 25 Hz (P < 0.001). Cisplatin showed a significant reduction in the % of survival (44.2-39.1%, P < 0.05) at 25 Hz and 47.5 microg/ml, and (b) Minor significant alterations were observed after nonsimultaneous exposure of cells to PEMF and drug. The data indicate that PEMF can induce modulation of cytostatic agents in HCA-2/1(cch), with an increased effect when PEMF was applied at the same time as the drug. The type of drug, dose, frequency, and duration of PEMF exposure could influence this modulation.

Factors confounding cytosolic calcium measurements in Jurkat E6.1 cells during exposure to ELF magnetic fields

Reported changes in the cytosolic calcium concentration ([Ca2+](c)) as a result of exposure to extremely low frequency (ELF) magnetic fields (MF) have been equivocal. In this study, we examine the possibility that some of these differences are attributable to variability associated with the cell cycle, pH of the suspension medium, and response to a calcium agonist. We used a custom designed spectrofluorimeter to measure [Ca2+](c) in Indo 1-AM loaded Jurkat E6.1 cells suspended in conditioned RPMI 1640 medium containing 10% fetal bovine serum. Four exposures were examined: zero static MF (Null), 60 Hz 100 microT(peak) sinusoidal MF (AC), 78 microT static MF (DC), and the combination of the 60 Hz and the 78 microT static MF (AD + DC). A significant decrease in normalized [Ca2+](c) values between 375-495 s for the DC and AC + DC groups was found in comparison to the Null group. However, statistical analysis indicated that cell cycle and quality of the alpha-CD3 monoclonal antibody response were significant covariates, while pH was not a significant covariate. When the effect of these covariates was taken into account, all exposure groups were significantly different from the control. Our results suggest that ELF MF effects may not be seen unless correction is made for biological variability of each cell preparation with respect to cell cycle and [Ca2+](c) response to antigen stimulation.

Action of extremely low frequency electric fields on the cytosolic calcium concentration of differentiated HL-60 cells: nonactivated cells

The effect of sinusoidal electric fields on the cytosolic free [Ca2+]i concentration in differentiated HL-60 cells was measured. The calcium concentration was measured in a fluorescence spectrometer using the fluorescence sample fluo-3. In the fluorescence spectrometer two samples can be measured simultaneously, one as the sham-exposed control and the other as the field-exposed sample. The effects of an external field, applied using two capacitor plates outside the cuvettes, and a field applied directly to the medium, using two platinum electrodes inside the cuvettes, were measured at selected frequencies between 0 and 100 Hz and field strengths from 1 to 2000 Vpp/m (external field) and from 0.1 to 1000 Vpp/m (in medium). No significant effects of the fields on the cytosolic free [Ca2+]i concentration in HL-60 cells have been observed at the measured frequencies and field strengths.

Effects of PEMF on a murine osteosarcoma cell line: drug-resistant (P-glycoprotein-positive) and non-resistant cells

After pulsed exposure of Dunn osteosarcoma cells (nonresistant cells) to Adriamycin (ADR) at increasing concentrations and single-cell cloning of surviving cells, ADR-resistant cells were obtained. These resistant cells expressed P-glycoprotein and had resistance more than 10 times that of their nonresistant parent cells. Compared to the nonresistant cells not exposed to pulsing electromagnetic fields (PEMF) in ADR-free medium, their growth rates at ADR concentrations of 0.01 and 0.02 micrograms/ml, which were below IC50, were 83.0% and 61.8%, respectively. On the other hand, in the nonresistant cells exposed to PEMF (repetition frequency, 10 Hz; rise time, 25 microsec, peak magnetic field intensity, 0.4-0.8 mT), the growth rate was 111.9% in ADR-free medium, 95.5% at an ADR concentration of 0.01 micrograms/ml, and 92.2% at an ADR concentration of 0.02 micrograms/ml. This promotion of growth by PEMF is considered to be a result of mobilization of cells in the non-proliferative period of the cell cycle due to exposure to PEMF. However, at ADR concentrations above the IC50, the growth rate tended to decrease in the cells not exposed to PEMF. This may be caused by an increase in cells sensitive to ADR resulting from mobilization of cells in the non-proliferative period to the cell cycle. The growth rate in the resistant cells exposed to PEMF was significantly lower than that in the non-exposed resistant cells at all ADR concentrations, including ADR-free culture (P</=0.0114). Therefore, this study suggests that PEMF promotes the growth of undifferentiated cells but progressively suppresses the growth of more differentiated cells, i.e., PEMF controls cell growth depending on the degree of cell differentiation. This study also shows the potentiality of PEMF as an adjunctive treatment method for malignant tumors.

Effect of electromagnetic fields on several CD markers and transcription and expression of CD4

We carried out flow cytometric analysis for multiparametric evaluation of cell surface markers related to cellular functions. Specifically, we studied the expression of CD4, CD8, CD3, CD16, CD19, HLA-DR, and CD14 macrophage receptors expression and cell cycle progression on cells exposed to ELF-EMF. In addition, we tested the effects of ELF-EMF on CD4 mRNA protein transcription and translation and the cell-cycle progression using an immunofluorescence method. Our data show that same CD surface marker expression are weakly influenced by electromagnetic fields, with no differences between cells exposed or not exposed to ELF-EMFs. However, when the CD4 protein generation was studied, an indication of protein production was found in lymphocytes exposed to ELF-EMF, as evidenced by immunofluorescence, Western blotting and RT-PCR analysis. CD16 and CD14 expression were affected by EMF exposure at all times studied (24, 48, 72 h). The results obtained with cell cycle analysis show that after 48 h of exposure to ELF-EMF, PHA-activated and not activated cells in S phase increase with respect to non-exposed cells. The findings from this study demonstrate that under our defined experimental conditions there is evidence that ELF-EMF has a slight effect on CD4, CD14 and CD16 receptor expression, while the other CD receptors are not affected.

Biological responses to electromagnetic fields

Electrification in developed countries has progressively increased the mean level of extremely low-frequency electromagnetic fields (ELF-EMFs) to which populations are exposed; these humanmade fields are substantially above the naturally occurring ambient electric and magnetic fields of approximately 10(-4) Vm(-1) and approximately 10(-13) T, respectively. Several epidemiological studies have concluded that ELF-EMFs may be linked to an increased risk of cancer, particularly childhood leukemia. These observations have been reinforced by cellular studies reporting EMF-induced effects on biological systems, most notably on the activity of components of the pathways that regulate cell proliferation. However, the limited number of attempts to directly replicate these experimental findings have been almost uniformly unsuccessful, and no EMF-induced biological response has yet been replicated in independent laboratories. Many of the most well-defined effects have come from gene expression studies; several attempts have been made recently to repeat these key findings. This review analyses these studies and summarizes other reports of major cellular responses to EMFs and the published attempts at replication. The opening sections discuss quantitative aspects of exposure to EMFs and the incidence of cancers that have been correlated with such fields. The concluding section considers the problems that confront research in this area and suggests feasible strategies.

Activation-dependent and biphasic electromagnetic field effects: model based on cooperative enzyme kinetics in cellular signaling

Experiments on filed exposure effects of extremely-low-frequency electric and magnetic fields (EMFs) on biological systems have shown that, in many cases, the biological-functional status is of fundamental importance for an effective interaction. For example, studies of calcium uptake regulation in cells of the immune system, particularly in T lymphocytes, have revealed that, depending on the degree of cellular activation, either stimulatory, inhibitory, or no field exposure effects are observed for identical field parameters. A brief summary of the experimental findings is given, and a theoretical approach is presented that accounts in a qualitative manner for EMF exposure effects 1) that depend on the degree of cellular activation and 2) that exhibit a biphasic response behavior (stimulation/ inhibition). In the model, biochemical stimulation of the cell results in activation of specific signaling pathways that regulate calcium dynamics in the cell (calcium release from intracellular calcium stores and capacitative calcium entry). We assume that, controlled by these pathways, a specific EMF-sensitive enzyme system becomes activated. The activated enzyme, in turn, exhibits a feedback control on the signal processes, thus leading to a modulation of calcium entry. This modulation may affect other cellular processes that are calcium dependent (e.g., DNA synthesis). Magnetic field exposure is assumed to alter the kinetics of a specific step within the enzyme-reaction cycle in accord with the radical-pair mechanism, although the formulism is not restricted to this specific example. Results show that inclusion of cooperative steps within the enzyme-reaction cycle provides a theoretical basis that enables a simple description of a biphasic response behavior to EMF exposure.

Pulsed magnetic field effects on calcium signaling in lymphocytes: dependence on cell status and field intensity

The effect of 3-Hz, monopolar, quasi-rectangular magnetic field pulses on 45Ca2+ uptake in resting and mitogen-treated rat thymic lymphocytes was evaluated. A 30-min, non-thermal exposure to the pulsed magnetic field (Bpeak = 6.5 mT, Emax = 0.69 mV/cm, Jmax = 2.6 microA/cm2) reduced Concanavalin A-induced 45Ca2+ uptake by 45%. It was observed that (i) the induction of the 3-Hz field response depended on Ca2+ signal transduction activation; (ii) the response direction (stimulation or inhibition) depended on the level of lymphocyte mitogen responsiveness, and (iii) the field response magnitude increased with increasing magnetic field flux densities (Bpeak = 0, 1.6, 6.5 and 28 mT). Our results demonstrate field effects at Bmax nearly 10(4) greater than that of the average human environment for low-frequency magnetic fields and they are consistent with the independent results from other 3-Hz pulsed magnetic field studies with lymphocytes.

Mechanisms of electromagnetic interaction with cellular systems

The question of how electromagnetic fields--static or low to high frequency--interact with biological systems is of great interest. The current discussion among biologists, chemists, and physicists emphasizes aspects of experimental verification and of defining microscopic and macroscopic mechanisms. Both aspects are reviewed here. We emphasize that in certain situations nonthermal interactions of electromagnetic fields occur with cellular systems.

Effects of pulsed electromagnetic fields on rat skin metabolism

In an attempt to approach the mechanism of action of pulsed electromagnetic fields (PEMF) on biological systems, the effects on protein synthesizing activity and on membrane transport have been examined in rat skin. PEMF characterized by specific physical parameters stimulate the incorporation of L-[U-14C]isoleucine into the proteins of rat skin as well as the alpha-amino[1-14C]isobutyric acid uptake during incubation in buffer medium with extracellular electrolyte composition. Analogous incubation experiments carried out in an intracellular medium results in an inhibitory effect of PEMF on both biological functions. Addition of 10(-3) M ouabain to the incubation medium, partially blocking the Na+/K+-ATPase pump mechanism, apart from reducing amino acid transport, results in an overall disappearance of any stimulatory effects by PEMF. PEMF applied to the skin in the presence of 10(-3) M 2,4-dinitrophenol uncoupling the oxidative phosphorylation in the mitochondria and seriously restricting protein synthesis, still provides a limited stimulatory effect on protein synthesizing activity and on membrane transport. The effects of PEMF may well be understood by an increased availability of precursor elements controlled at the cell membrane level. Indeed the observed effects may even be simulated outside electromagnetic fields by modifications in the electrolyte composition of the incubation medium.

Magnetic field inhibition of morphine-induced analgesia and behavioral activity in mice: evidence for involvement of calcium ions

An exposure for 60 min to a 0.5 Hz rotating magnetic field (1.5-90 G) significantly reduced the day-time analgesic (in CF-1 mice) and locomotory (in C-57BL mice) effects of morphine (10 mg/kg). Intracerebroventricular (i.c.v.) injections of a calcium chelator, EGTA, blocked these effects, while administration of the calcium ionophore, A23187, potentiated the inhibitory actions. In a parallel fashion, i.c.v. administration of Ca2+ reduced, in a dose-related manner, the analgesic and locomotory effects of morphine in control CF-1 and C57 mice. These latter inhibitory effects could also be blocked by EGTA and augmented by A23187, indicating that opiate effects on activity and nociception are both sensitive to antagonism by calcium. Taken together these results suggest that exposure to magnetic stimuli may alter morphine-induced responses in mice, in a manner compatible and consistent with effects on Ca2+ and possibly other divalent ions.