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Permeability of the blood‐brain barrier induced by 915 MHz electromagnetic radiation, continuous wave and modulated at 8, 16, 50, and 200 Hz

Salford, Leif G. LU ; Brun, Arne LU ; Sturesson, Kerstin ; Eberhardt, Jacob L. LU and Persson, Bertil R.R. LU (1994) In Microscopy Research and Technique 27(6). p.535-542
Abstract

Biological effects of electromagnetic fields (EMF) on the blood‐brain barrier (BBB) can be studied in sensitive and specific models. In a previous investigation of the permeability of the blood‐brain barrier after exposure to the various EMF‐components of proton magnetic resonance imaging (MRI), we found that the exposure to MRI induced leakage of Evans Blue labeled proteins normally not passing the BBB of rats [Salford et al. (1992), in: Resonance Phenomena in Biology, Oxford University Press, pp. 87–91]. In the present investigation we exposed male and female Fischer 344 rats in a transverse electromagnetic transmission line chamber to microwaves of 915 MHz as continuous wave (CW) and pulse‐modulated with repetition rates of 8, 16,... (More)

Biological effects of electromagnetic fields (EMF) on the blood‐brain barrier (BBB) can be studied in sensitive and specific models. In a previous investigation of the permeability of the blood‐brain barrier after exposure to the various EMF‐components of proton magnetic resonance imaging (MRI), we found that the exposure to MRI induced leakage of Evans Blue labeled proteins normally not passing the BBB of rats [Salford et al. (1992), in: Resonance Phenomena in Biology, Oxford University Press, pp. 87–91]. In the present investigation we exposed male and female Fischer 344 rats in a transverse electromagnetic transmission line chamber to microwaves of 915 MHz as continuous wave (CW) and pulse‐modulated with repetition rates of 8, 16, 50, and 200 s−1. The specific energy absorption rate (SAR) varied between 0.016 and 5 W/kg. The rats were not anesthetized during the 2‐hour exposure. All animals were sacrificed by perfusion‐fixation of the brains under chloral hydrate anesthesia about 1 hour after the exposure. The brains were perfused with saline for 3–4 minutes, and thereafter fixed in 4% formaldehyde for 5–6 minutes. Central coronal sections of the brains were dehydrated and embedded in paraffin and sectioned at 5 μm. Albumin and fibrinogen were demonstrated immunohistochemically. The results show albumin leakage in 5 of 62 of the controls and in 56 of 184 of the animals exposed to 915 MHz microwaves. Continuous wave resulted in 14 positive findings of 35, which differ significantly from the controls (P = 0.002). With pulsed 915 MHz microwaves with repetition rates of 200, 50, 16, and 8 s−1, 42 of 149 were positive, which is highly significant at the P = 0.001 level. This reveals that both CW and pulsed 915 MHz microwaves have the potential to open up the BBB for albumin passage. However, there is no significant difference between continuous and pulsed 915 MHz microwaves in this respect. The frequency of occurrence of extravasates (26%) was found to be independent of SAR for SAR < 2.5 W/kg, but rose significantly for the higher SAR values (to 43%). The question of whether the opening of the blood‐brain barrier constitutes a health hazard demands further investigation. © 1994 Wiley‐Liss, Inc.

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organization
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Contribution to journal
publication status
published
keywords
Albumin, Electromagnetic fields, Fibrinogen, Immunohistochemistry, Rat
in
Microscopy Research and Technique
volume
27
issue
6
pages
8 pages
publisher
John Wiley and Sons Inc.
external identifiers
  • pmid:8012056
  • scopus:0028325167
ISSN
1059-910X
DOI
10.1002/jemt.1070270608
language
English
LU publication?
yes
id
24920e91-f6a5-44b2-92e8-3e0afc744437
date added to LUP
2020-05-12 12:31:34
date last changed
2020-05-24 06:31:54
@article{24920e91-f6a5-44b2-92e8-3e0afc744437,
  abstract     = {<p>Biological effects of electromagnetic fields (EMF) on the blood‐brain barrier (BBB) can be studied in sensitive and specific models. In a previous investigation of the permeability of the blood‐brain barrier after exposure to the various EMF‐components of proton magnetic resonance imaging (MRI), we found that the exposure to MRI induced leakage of Evans Blue labeled proteins normally not passing the BBB of rats [Salford et al. (1992), in: Resonance Phenomena in Biology, Oxford University Press, pp. 87–91]. In the present investigation we exposed male and female Fischer 344 rats in a transverse electromagnetic transmission line chamber to microwaves of 915 MHz as continuous wave (CW) and pulse‐modulated with repetition rates of 8, 16, 50, and 200 s<sup>−1</sup>. The specific energy absorption rate (SAR) varied between 0.016 and 5 W/kg. The rats were not anesthetized during the 2‐hour exposure. All animals were sacrificed by perfusion‐fixation of the brains under chloral hydrate anesthesia about 1 hour after the exposure. The brains were perfused with saline for 3–4 minutes, and thereafter fixed in 4% formaldehyde for 5–6 minutes. Central coronal sections of the brains were dehydrated and embedded in paraffin and sectioned at 5 μm. Albumin and fibrinogen were demonstrated immunohistochemically. The results show albumin leakage in 5 of 62 of the controls and in 56 of 184 of the animals exposed to 915 MHz microwaves. Continuous wave resulted in 14 positive findings of 35, which differ significantly from the controls (P = 0.002). With pulsed 915 MHz microwaves with repetition rates of 200, 50, 16, and 8 s<sup>−1</sup>, 42 of 149 were positive, which is highly significant at the P = 0.001 level. This reveals that both CW and pulsed 915 MHz microwaves have the potential to open up the BBB for albumin passage. However, there is no significant difference between continuous and pulsed 915 MHz microwaves in this respect. The frequency of occurrence of extravasates (26%) was found to be independent of SAR for SAR &lt; 2.5 W/kg, but rose significantly for the higher SAR values (to 43%). The question of whether the opening of the blood‐brain barrier constitutes a health hazard demands further investigation. © 1994 Wiley‐Liss, Inc.</p>},
  author       = {Salford, Leif G. and Brun, Arne and Sturesson, Kerstin and Eberhardt, Jacob L. and Persson, Bertil R.R.},
  issn         = {1059-910X},
  language     = {eng},
  month        = {01},
  number       = {6},
  pages        = {535--542},
  publisher    = {John Wiley and Sons Inc.},
  series       = {Microscopy Research and Technique},
  title        = {Permeability of the blood‐brain barrier induced by 915 MHz electromagnetic radiation, continuous wave and modulated at 8, 16, 50, and 200 Hz},
  url          = {http://dx.doi.org/10.1002/jemt.1070270608},
  doi          = {10.1002/jemt.1070270608},
  volume       = {27},
  year         = {1994},
}