Study type: Medical/biological study (experimental study)

Effects of electromagnetic fields on isolated nerve and muscle preparations med./bio.

By: Chou CK, Guy AW
Published in: IEEE Trans Microw Theory Tech 1978; 26 (3): 141-147
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Aim of study (acc. to editor)

To study the effects of electromagnetic fields on isolated nerve and muscle preparations.

Background/further details

Compound action potentials of nerves or contractile tensions of muscles were recorded.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2,450 MHz
Modulation type: CW
Exposure duration: intermittent, 10 or 5 min on/5 min off
isolated nerves and ganglia
Exposure 2: 2,450 MHz
Modulation type: pulsed
Exposure duration: intermittent, 10 or 5 min on/5 min off
isolated nerves and ganglia
Exposure 3: 2,450 MHz
Modulation type: pulsed
Exposure duration: intermittent, 10 or 5 min on/5 min off
isolated nerves and ganglia
Exposure 4: 2,450 MHz
Modulation type: CW
Exposure duration: intermittent, 5 min on/5-10 min off
isolated muscles
Exposure 5: 2,450 MHz
Modulation type: pulsed
Exposure duration: intermittent, 5 min on/5-10 min off
isolated muscles
Exposure 6: 2,450 MHz
Modulation type: pulsed
Exposure duration: intermittent, 5 min on/5-10 min off
isolated muscles

Exposure 1

Main characteristics
Frequency 2,450 MHz
Type
Charakteristic
  • guided field
Exposure duration intermittent, 10 or 5 min on/5 min off
Additional info isolated nerves and ganglia
Modulation
Modulation type CW
Exposure setup
Exposure source
Chamber The temperature of the exposed tissue was maintained at 37°C by circulating temperature controlled Ringer's solution through the waveguide. (The frog sciatic nerve was kept at room temperature.) A maximum rise of 1°C occurred during irradiation due to the limited circulation rate. The waveguide was pointed upward with a Plexiglas solution reservoir on the top edge. A quarter wavelength dielectric matching material was placed between the 6 cm deep Ringer's solution and the air medium. A VSWR of 1.08 was measured.
Setup Nerves and ganglia were placed in the waveguide either parallel or perpendicular to the electric field of the TE10 mode. They were exposed to each power level for 10 or 5-min periods, respectively, separated by 5-min intervals.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.3 W/kg mean determined by power loss - -
SAR 3 W/kg mean determined by power loss - -
SAR 30 W/kg mean determined by power loss - -
SAR 300 W/kg mean determined by power loss - -
SAR 1,500 W/kg mean determined by power loss - -
Additional parameter details

Stimulation current pulses of 0.3 ms and 0.3-30 mA were applied to the nerves once every 2 s. Tests for possible direct stimulation of nerves and ganglia by MW fields were also performed at the maximum SAR values for CW and pulsed fields but without the electrical stimulation.

Measurement and calculation details

Incident and reflected powers were measured using a directional coupler, two bolometers and two power meters. SAR values derived from temperature rise measurements [Johnson et al., 1972 and 1975] were 10% lower than the theoretical values calculated from power loss.

Exposure 2

Main characteristics
Frequency 2,450 MHz
Type
Charakteristic
  • guided field
Exposure duration intermittent, 10 or 5 min on/5 min off
Additional info isolated nerves and ganglia
Modulation
Modulation type pulsed
Pulse width 1 µs
Repetition frequency 1,000 Hz
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.3 W/kg mean determined by power loss - -
SAR 3 W/kg mean determined by power loss - -
SAR 30 W/kg mean determined by power loss - -
SAR 220 W/kg mean determined by power loss - -

Exposure 3

Main characteristics
Frequency 2,450 MHz
Type
Charakteristic
  • guided field
Exposure duration intermittent, 10 or 5 min on/5 min off
Additional info isolated nerves and ganglia
Modulation
Modulation type pulsed
Pulse width 10 µs
Repetition frequency 100 Hz
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.3 W/kg mean determined by power loss - -
SAR 3 W/kg mean determined by power loss - -
SAR 30 W/kg mean determined by power loss - -
SAR 220 W/kg mean determined by power loss - -

Exposure 4

Main characteristics
Frequency 2,450 MHz
Type
Charakteristic
  • guided field
Exposure duration intermittent, 5 min on/5-10 min off
Additional info isolated muscles
Modulation
Modulation type CW
Exposure setup
Exposure source
Setup Muscles were placed in the waveguide either parallel or perpendicular to the electric field of the TE10 mode. They were exposed to each power level for 5-min periods, separated by 5 to 10-min intervals.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.3 W/kg mean determined by power loss - -
SAR 3 W/kg mean determined by power loss - -
SAR 30 W/kg mean determined by power loss - -
SAR 300 W/kg mean determined by power loss - -
SAR 1,500 W/kg mean determined by power loss - -
Additional parameter details

Stimulation current pulses of 0.3 ms and 0.3-30 mA were applied to the phrenic nerves once every 5 s for single twitch experiments and 15-30 per second for tetanus experiments. Tests for possible direct influence of MW fields on muscle tension were also performed at the maximum SAR values for CW and pulsed fields but without the electrical stimulation.

Exposure 5

Main characteristics
Frequency 2,450 MHz
Type
Charakteristic
  • guided field
Exposure duration intermittent, 5 min on/5-10 min off
Additional info isolated muscles
Modulation
Modulation type pulsed
Pulse width 1 µs
Repetition frequency 1,000 Hz
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.3 W/kg mean determined by power loss - -
SAR 3 W/kg mean determined by power loss - -
SAR 30 W/kg mean determined by power loss - -
SAR 220 W/kg mean determined by power loss - -

Exposure 6

Main characteristics
Frequency 2,450 MHz
Type
Charakteristic
  • guided field
Exposure duration intermittent, 5 min on/5-10 min off
Additional info isolated muscles
Modulation
Modulation type pulsed
Pulse width 10 µs
Repetition frequency 100 Hz
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.3 W/kg mean determined by power loss - -
SAR 3 W/kg mean determined by power loss - -
SAR 30 W/kg mean determined by power loss - -
SAR 220 W/kg mean determined by power loss - -

Reference articles

  • Johnson CC et al. (1975): Discussion paper: Fiberoptic liquid crystal probe for absorbed radio-frequency power and temperature measurement in tissue during irradiation
  • Johnson CC et al. (1972): Nonionizing electromagnetic wave effects on biological material and systems

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Continuous wave and pulsed 2450 MHz electromagnetic fields produce no effects other than thermal effect on the conduction characteristics of isolated nerves or on the contraction of isolated muscles.

Study character:

Study funded by

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