Study type: Medical/biological study (experimental study)

Effects of extremely low frequency electromagnetic fields on membrane-associated enzymes. med./bio.

Published in: Arch Biochem Biophys 2005; 441 (2): 191-198

Aim of study (acc. to author)

To study the effects of extremely low frequency electromagnetic fields of 75 Hz on different membrane-associated enzymes.

Background/further details

The choice was done among integral membrane proteins (calcium-ATPase, sodium potassium ATPase, succinate dehydrogenase), peripheral membrane proteins (photoreceptor phosphodiesterase 6), and lipid-linked proteins (alkaline phosphatase, acetylcholinesterase).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 75 Hz
Modulation type: pulsed
Exposure duration: continuous for 1, 2, 3, 5, 10, 20 and/or 30 min
Exposure 2: 75 Hz
Modulation type: pulsed
Exposure duration: continuous for 10 min
-

Exposure 1

Main characteristics
Frequency 75 Hz
Type
Waveform
Exposure duration continuous for 1, 2, 3, 5, 10, 20 and/or 30 min
Modulation
Modulation type pulsed
Additional info

Square wave with a duty cycle of 10%

Exposure setup
Exposure source
Setup The sample were placed in the center of the coils. Control were run in the same experimental conditions but in the absence of magnetic field.
Additional info Different magnetic fields were obtained by changing the distance between the coils.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 2.5 mT - measured - at a distance of 3 cm between the coils

Exposure 2

Main characteristics
Frequency 75 Hz
Type
Waveform
Exposure duration continuous for 10 min
Modulation
Modulation type pulsed
Additional info

Square wave with a duty cycle of 10%

Exposure setup
Exposure source
Parameters

No parameters are specified for this exposure.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

The activities of three enzymes out of seven exposed to the electromagnetic field decreased approximately of about 54-61 % with field amplitudes above a threshold of 73-151 µT depending on the enzyme. The same field had no effect on the activities of either integral membrane enzymes such as calcium-ATPase, sodium potassium ATPase, succinate dehydrogenase or peripheral membrane enzymes (photoreceptor phosphodiesterase 6).
The decrease in enzyme activity of the field-sensitive enzymes was independent of the time of permanence in the electromagnetic field and was completely reversible. When these enzymes were solubilized with Triton, no effect of the field was revealed on the enzyme activity, suggesting the crucial role of the membrane in determining the conditions for enzyme inactivation.

Study character:

Study funded by

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