| 1. |
- Kaviani Moghadam, Mehri, et al.
(författare)
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Effects of Weak Environmental Magnetic Fields on the Spontaneous Bioelectrical Activity of Snail Neurons
- 2011
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Ingår i: Journal of Membrane Biology. - : Springer Science and Business Media LLC. - 0022-2631 .- 1432-1424. ; 240:2, s. 63-71
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Tidskriftsartikel (refereegranskat)abstract
- We examined the effects of 50-Hz magnetic fields in the range of flux densities relevant to our current environmental exposures on action potential (AP), after-hyperpolarization potential (AHP) and neuronal excitability in neurons of land snails, Helix aspersa. It was shown that when the neurons were exposed to magnetic field at the various flux densities, marked changes in neuronal excitability, AP firing frequency and AHP amplitude were seen. These effects seemed to be related to the intensity, type (single and continuous or repeated and cumulative) and length of exposure (18 or 20 min). The extremely low-frequency (ELF) magnetic field exposures affect the excitability of F1 neuronal cells in a nonmonotonic manner, disrupting their normal characteristic and synchronized firing patterns by interfering with the cell membrane electrophysiological properties. Our results could explain one of the mechanisms and sites of action of ELF magnetic fields. A possible explanation of the inhibitory effects of magnetic fields could be a decrease in Ca2+ influx through inhibition of voltage-gated Ca2+ channels. The detailed mechanism of effect, however, needs to be further studied under voltage-clamp conditions.
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| 2. |
- Kaviani Moghadam, Mehri, et al.
(författare)
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Weak Environmental Magnetic Fields Inhibit Spontaneous Bioelectrical Activity in Snail Neurons
- 2010
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Ingår i: Advances in Biomedical Research, Proceedings. - 1790-5125. ; , s. 288-294
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Konferensbidrag (refereegranskat)abstract
- The interest in the evaluation of health effects due to EMF has accelerated in the last decades, mostly motivated by the occupational and environmental exposures to humans by such non-ionizing fields. The increasing exposure to electromagnetic fields has been suspected to contribute to the rising incidence of cancer in industrialized countries Despite detailed analysis which provide a wealth of accurate data on the effects of electromagnetic fields on nerve cells, a clear pictures of the mechanism and sites of action of ELF magnetic field in the range of environmental intensities is far from being accomplished and the ionic or metabolic processes underlying the observed effects have not been fully explained. The aim of this study was to evaluate the effects of 50 Hz magnetic fields in the range of environmental intensities on spike and neuronal excitability in snail neurons. We measured the bioelectric parameters of F1 neuron with the conventional intracellular recording in current clamp mode.
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| 3. |
- Nittby, Henrietta, et al.
(författare)
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Analgetic effects of non-thermal GSM-1900 radiofrequency electromagnetic fields in the land snail Helix pomatia
- 2012
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Ingår i: International Journal of Radiation Biology. - : Informa UK Limited. - 0955-3002 .- 1362-3095. ; 88:3, s. 245-252
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Tidskriftsartikel (refereegranskat)abstract
- Purpose : To investigate whether mobile phone radiation might affect snail nociception, employing radiofrequency (RF) electromagnetic fields (EMF) which, to our knowledge, have hitherto not been studied in a snail model. Exposure to extremely low frequency (ELF) magnetic fields has however been shown to significantly affect nociceptive responses. Materials and methods : In the present study, we exposed 29 land snails of the strain Helix pomatia to global system for mobile communications (GSM) EMF at 1900 MHz at the non-thermal level 48 mW/kg for 1 hour each and 29 snails were sham controls. The experiments took place during the onset of summer, with all snails being well out of hibernation. Before and after GSM or sham exposure, the snails were subjected to thermal pain by being placed on a hot plate. The reaction time for retraction from the hot plate was measured by two blinded observers. Results : Comparing the reaction pattern of each snail before and after exposure, the GSM-exposed snails were less sensitive to thermal pain as compared to the sham controls, indicating that RF exposure induces a significant analgesia (Mann-Whitney p < 0.001). Conclusion : This study might support earlier findings, describing beneficial effects of EMF exposure upon nociception.
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| 4. |
- Nittby, Henrietta, et al.
(författare)
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Nonthermal GSM RF and ELF EMF effects upon rat BBB permeability
- 2011
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Ingår i: The Environmentalist. - : Springer Science and Business Media LLC. - 0251-1088 .- 1573-2991. ; 31:2, s. 140-148
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Tidskriftsartikel (refereegranskat)abstract
- Since the late 1980s, our group has examined the effects of radiofrequency electromagnetic fields (RF-EMF), including pulse-modulated waves of the type emitted by mobile phones, upon the blood-brain barrier. In more than 2,000 rats, we have repeatedly demonstrated a passage of the rats' own albumin from the blood through the brain capillaries into the surrounding brain parenchyma at SAR values down to 0.1mW/kg. In most of these experiments, the animals were exposed in TEM-cells, ventilated by an external electrical fan at 50 Hz. In the present study, we examined whether the extremely low frequency (ELF) magnetic fields from the fan (50 Hz, 0.3-1.5 μT) might add to the RF effect. Sixty-four rats were divided into 4 groups: RF only, ELF only and RF + ELF exposure plus a sham group. The GSM-900 MHz RF exposure was at the very low, nonthermal, average whole-body SAR level 0.4 mW/kg. Demonstration of the normally occurring albumin extravasation in the basal hypothalamus is our inbuilt control proving that the staining is reliable. Two full series of staining of the whole material gave negative results for hypothalamus. Not until we changed to avidin, biotin, and antibodies from a third supplier, we received an acceptable staining. Twenty-five percent of the RF animals had a pathological albumin leakage, while the ELF and RF + ELF groups with three and two pathological findings, respectively, were not significantly different from the control group. We conclude that the use of external fans has had no major influence upon the result.
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| 5. |
- Sun, Wenjun J., et al.
(författare)
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Calcium efflux of plasma membrane vesicles exposed to ELF magnetic fieldsutest of a nuclear magnetic resonance interaction model
- 2012
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Ingår i: Bioelectromagnetics. - : Wiley. - 0197-8462. ; 33:7, s. 535-542
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Tidskriftsartikel (refereegranskat)abstract
- The question whether very weak, low frequency magnetic fields can affect biological matter is still under debate. The theoretical possibility of such an interaction is often questioned and the site of interaction in the cell is unknown. In the present study, the influence of extremely weak 60?Hz magnetic fields on the transport of Ca2+ was studied in a biological system consisting of highly purified plasma membrane vesicles. We tested a newly proposed quantum mechanical model postulates that polarization of hydrogen nuclei can elicit a biological effect. Vesicles were exposed for half an hour at 32?degrees C and the calcium efflux was studied using radioactive 45Ca2+ as a tracer. A static magnetic field of 26?mu T and time-varying magnetic fields with a frequency of 60?Hz and amplitudes between 0.6 and 6.3?mu T were used. The predictions of the model, proposed by Lednev, that at a frequency of 60?Hz the biological effect under investigation would significantly be altered at the amplitudes of 1.3 and 3.9?mu T could not be confirmed. Bioelectromagnetics 33:535542, 2012. (c) 2012 Wiley Periodicals, Inc.
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