Study type: Medical/biological study (experimental study)

Exposure to 50 Hz electromagnetic field changes the efficiency of the scorpion alpha toxin. med./bio.

Published in: J Venom Anim Toxins Incl Trop Dis 2015; 21: 38

Aim of study (acc. to author)

The effects of an in vivo exposure of cockroaches and an in vitro exposure of cockroach nerves to a 50 Hz magnetic field on the effects of the scorpion alpha toxin should be investigated.

Background/further details

The scorpion alpha toxin LqhαIT is a polypeptide highly active on insects. It binds to the sodium ion channels of nerves and inactivates them, causing hyper-excitation and paralysis. Magnetic fields might alter the effects of the toxin by modulating the nerve membrane potential and changing the binding properties or by influencing the neural transmission. The authors propose that in vitro and in vivo tests with the toxin could be a useful tool for distinguishing between primary and secondary effects of the magnetic field.
For the in vitro experiments, the abdominal nerve cord was isolated from the body of a cockroach together with the cercal nerve linked to the cerci (paired appendages of insects) and placed in culture medium. The following groups were observed (n=15 measurements each): 1) exposure to a 0.7 mT magnetic field only, 2) LqhαIT (5 Œ 10-8 M) administration only, 3) co-exposure to a 0.7 mT magnetic field and LqhαIT administration and 4) control group without exposure and with a sham administration (saline).
For the in vivo experiments cockroaches were divided into 3 groups (n=15 each): 5) exposure to a 0.7 mT magnetic field, 6) exposure to a 7 mT magnetic field and 7) sham exposure. Immediately before the beginning of the exposure, each insect was injected with 5 µl of LqhαIT (10-8 M; sublethal dose) and the animals were investigated after 1 h, 2 h and 24 hours of exposure.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 7 minutes
in vitro tests
Exposure 2: 50 Hz
Exposure duration: continuous for up to 24 hours
in vivo tests
Exposure 3: 50 Hz
Exposure duration: continuous for up to 24 hours
in vivo tests

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Exposure duration continuous for 7 minutes
Additional info in vitro tests
Exposure setup
Exposure source
Chamber experimental chamber
Setup the coil (7 cm in diameter Π2 cm) was installed around the experimental chamber and produced a homogeneous field (maximum non-uniformity 16%); no changes in temperature were measured during exposure
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.7 mT - - - -

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for up to 24 hours
Additional info in vivo tests
Additional info vertical polarization (field lines perpendicular to the bottom plane of the animals' cage)
Exposure setup
Exposure source
Chamber glass chamber (15 cm Π7.5 cm in diameter)
Setup coil wound around a plastic cylinder of 19 cm (inner diameter) and 21 cm in length; coil was able to ensure the maximum homogeneity (within 8%) in a central cylindrical area (radius and height of 7.5 cm) where glass chamber with free moving insects was placed; coil was located in an isolated room (temperature: 23 ± 1°C)
Sham exposure A sham exposure was conducted.
Additional info sham apparatus with the same size and temperature but lacking a coil was constructed
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.7 mT - measured - -

Exposure 3

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for up to 24 hours
Additional info in vivo tests
Additional info vertical polarization (field lines perpendicular to the bottom plane of the animals' cage)
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 7 mT - measured - -

Reference articles

  • Trawinski T et al. (2010): Analysis of Magnetic Field Distribution and Mechanical Vibration of Magnetic Field Exciter under Different Voltage Supply.

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

In the in vitro experiments, administration of LqhαIT (group 2) led to a significantly increased bioelectrical activity in the cercal nerve compared to the control. Co-exposure to the toxin and to the magnetic field (group 3) attenuated the effect of the toxin. In the abdominal nerve, the administration of LqhαIT (group 2) led to a significantly increased bioelectrical activity similar to the cercal nerve, but co-exposure to the toxin and to the magnetic field (group 3) significantly increased the effect of the toxin in comparison to the control. In both nerves, the activity was decreased (remark EMF-Portal: significance unclear) compared to the control when the nerves were exposed to the magnetic field alone (group 1).
In the in vivo tests, exposure to the 0.7 mT (group 5) led to significantly reduced paralysis effects after 1 hours and 24 hours compared to sham exposed group (group 7). Exposure to the 7 mT (group 6) had a stronger effect and led to significantly reduced paralysis effects after 1 h, 2 h and 24 hours.
The authors conclude that exposure to a 50 Hz magnetic field could modify the effects of the scorpion alpha toxin in cockroaches. They suggest a primary effect of the magnetic field on the nerves and a secondary effect on the metabolism.

Study character:

Study funded by

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