Study type: Medical/biological study (experimental study)

Fifty-hertz magnetic fields induce free radical formation in mouse bone marrow-derived promonocytes and macrophages. med./bio.

Published in: Biochimica et Biophysica Acta - General Subjects 2004; 1674 (3): 231-238

Aim of study (acc. to author)

To study the effects of 50 Hz magnetic field on free radical production in mouse bone marrow-derived macrophages and monocytes.

Background/further details

LPS (lipopolysaccharides; to study the influence of the magnetic field on differentiated macrophages and their nitric oxide production; LPS activates the nitric oxide synthase) and TPA (tetradecanoylphorbol acetate; TPA is known to induce a direct activation of NADPH-oxidase) were used as positive controls.
Enzymes such as NAD(P)H-oxidases mediate the main production of free radicals (ROS) in macrophages. The authors assume that the activation of NADH-oxidase plays a major role in phagocytic cells and is responsible for the magnetic field-induced free radical production. To study this, the specific NADPH-oxidase inhibitor DPI (diphenyleneiodonium chloride) was used, which does not affect NADH-oxidase activity. It makes it possible to distinguish between the two pathways (NADH-oxidase/NADPH-oxidase).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: experiment 1: 45 min; experiment 2: 45 min up to 24 h

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Exposure duration experiment 1: 45 min; experiment 2: 45 min up to 24 h
Exposure setup
Exposure source
Chamber Incubator containg 5% CO2 and maintained at 37°C
Setup Cultue plates were placed in the center of the coils, which were located in the middle of the incubator
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT unspecified measured - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The results show a significant increase of free radical production after exposure to 50 Hz electromagnetic fields to promonocytes and macrophages, indicating the cell-activating capacity of extremely low frequency magnetic fields.
After exposure mainly superoxide anion radicals were produced, both in macrophages and also in their precursor cells (monocytes). Magnetic field-induced free radical production was not inhibited by DPI, whereas TPA-induced free radical production was diminished by about 70%. Since DPI lacks an inhibitory effect in magnetic field-exposed cells, the authors suggest that 50 Hz magnetic field stimulates the NADH-oxidase pathway to produce superoxide anion radicals, but not the NADPH pathway. Magnetic field-exposed cells show no detectable production of NO2-.

Study character:

Study funded by

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