Study type: Medical/biological study (experimental study)

An incoherent magnetic field inhibited EGF receptor clustering and phosphorylation induced by a 50-Hz magnetic field in cultured FL cells med./bio.

By: Sun W, Gan Y, Fu Y, Lu D, Chiang H
Published in: Cell Physiol Biochem 2008; 22 (5-6): 507-514
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Aim of study (acc. to author)

To study the effects of 50 Hz magnetic field exposure at different intensities on epidermal growth factor receptor (EGFR) clustering and phosphorylation in human amniotic cells, and explored the interaction effect of an incoherent magnetic field.

Background/further details

Based on previous data (Sun et al. 2001), the authors hypothesized that membrane proteins, especially membrane receptors are the initial target sites of extremely low frequency electromagnetic fields.
Cells were divided into five groups: a) positive control (cells were treated with 100 ng/ml EGF for 15 min), b) sham exposure, c) 50 Hz magnetic field exposure (at 0.05, 0.1, 0.2, or 0.4 mT), d) incoherent magnetic field exposure (0.2 mT "noise" magnetic field), and e) combined magnetic field exposure (superposition of "noise" and 50 Hz magnetic field).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 15 min
Exposure 2: 30–90 Hz
Exposure duration: continuous for 15 min
Exposure 3: 30–90 Hz
Exposure duration: continuous for 15 min

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for 15 min
Exposure setup
Exposure source
Setup group of three 36 cm x 36 cm copper coils with 168, 60 and 168 turns, placed in a metal container inside an incubator
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.05 mT minimum measured - -
magnetic flux density 0.1 mT - measured - -
magnetic flux density 0.2 mT - measured - -
magnetic flux density 0.4 mT maximum measured - -

Exposure 2

Main characteristics
Frequency 30–90 Hz
Type
Exposure duration continuous for 15 min
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.2 mT - measured - -

Exposure 3

Main characteristics
Frequency 30–90 Hz
Type
Exposure duration continuous for 15 min
Additional info 50 Hz sinusoidal signal superimposed on the 30 Hz - 90 Hz signal
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.2 mT - measured - 30 Hz - 90 Hz signal
magnetic flux density 0.1 mT - measured - 50 Hz signal
magnetic flux density 0.2 mT - measured - 50 Hz signal
magnetic flux density 0.4 mT - measured - 50 Hz signal

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The data showed that, compared with sham exposure, exposure to a 50 Hz magnetic field at 0.1, 0.2 or 0.4 mT for 15 min could significantly induce EGF receptor clustering and enhance phosphorylation in FL cells, whereas exposure to a 0.05 mT field for 15 min did not cause a significant effect (group c).
Exposure to an incoherent magnetic field (frequency range between 30 to 90 Hz) at 0.2 mT neither induced EGF receptor clustering nor enhanced phosphorylation (group d).
When superposed, the incoherent magnetic field at 0.2 mT completely inhibited EGF receptor clustering and phosphorylation induced by a 50 Hz magnetic field at 0.1 and 0.2 mT (group e). However, the incoherent magnetic field could not completely eliminate the effects induced by 0.4 mT.
In conclusion, membrane receptors could be one of the main targets where extremely low frequency magnetic fields interact with cells, and the intensity threshold of the magnetic field, in the case of EGF receptors, is between 0.05 and 0.1 mT. An incoherent magnetic field could completely inhibit the effects induced by an extremely low frequency magnetic field of equal or lower intensity.

Study character:

Study funded by

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