Study type: Medical/biological study (experimental study)

Exposure of frog hearts to CW or amplitude-modulated VHF fields: selective efflux of calcium ions at 16 Hz med./bio.

By: Schwartz JL, House DE, Mealing GA
Published in: Bioelectromagnetics 1990; 11 (4): 349-358
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Aim of study (acc. to author)

To investigate the effects of a 240 MHz CW or AM VHF field on the calcium efflux of isolated frog hearts. The AM VHF field was modulated at 0.5 or 16 Hz.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 240 MHz
Modulation type: CW
Exposure duration: continuous 30 min
  • SAR: 3 mW/kg maximum (1.5 mW/kg, 0.36 mW/kg, 0.3 mW/kg, 0.24 mW/kg or 0.15 mW/kg)
Exposure 2: 240 MHz
Modulation type: AM
Exposure duration: continuous 30 min
  • SAR: 3 mW/kg maximum (1.5 mW/kg, 0.36 mW/kg, 0.3 mW/kg, 0.24 mW/kg or 0.15 mW/kg)
Exposure 3: 240 MHz
Modulation type: AM
Exposure duration: continuous 30 min
  • SAR: 3 mW/kg maximum (1.5 mW/kg, 0.36 mW/kg, 0.3 mW/kg, 0.24 mW/kg or 0.15 mW/kg)

Exposure 1

Main characteristics
Frequency 240 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous 30 min
Modulation
Modulation type CW
Exposure setup
Exposure source
  • 240 MHz generated with sweep generator
Chamber Crawford Cell (2 x 0.6 x 0.5 m) with the distance between each ground plane and the septum was 0.3 m.
Setup 4 or 8 hearts were exposed at a time by placing in sample vial holders. The vials containing the hearts were spaced 60 mm from each other to prevent interference. Two specimen holders were always loaded with vials even when no heart was present in them to keep a balanced load on each side of the exposure cell septum. Each control group was subjected to same conditions as the exposure groups but with the generator switched off.
Additional info Hearts were electrically paced and the stimulus was a pulse of 4 ms duration.
Parameters
Measurand Value Type Method Mass Remarks
SAR 3 mW/kg maximum determined by power loss - 1.5 mW/kg, 0.36 mW/kg, 0.3 mW/kg, 0.24 mW/kg or 0.15 mW/kg
Measurement and calculation details

Power levels of incident and reflected fields were monitored by two power meters connected to bi-directional coupler.

Exposure 2

Main characteristics
Frequency 240 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous 30 min
Additional info 0.5 Hz amplitude modulation
Modulation
Modulation type AM
Modulation frequency 500 mHz
Modulation depth 90 %
Exposure setup
Exposure source
Setup Same as in E1.
Parameters
Measurand Value Type Method Mass Remarks
SAR 3 mW/kg maximum determined by power loss - 1.5 mW/kg, 0.36 mW/kg, 0.3 mW/kg, 0.24 mW/kg or 0.15 mW/kg

Exposure 3

Main characteristics
Frequency 240 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous 30 min
Additional info 16 Hz amplitude modulation
Modulation
Modulation type AM
Modulation frequency 16 Hz
Modulation depth 90 %
Exposure setup
Exposure source
  • Same as in E2
Setup Same as in E1
Parameters
Measurand Value Type Method Mass Remarks
SAR 3 mW/kg maximum determined by power loss - 1.5 mW/kg, 0.36 mW/kg, 0.3 mW/kg, 0.24 mW/kg or 0.15 mW/kg

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

Neither CW irradiation nor AM irradiation, modulated at 0.5 Hz, were found to be capable to affect the calcium efflux of isolated frog hearts. Whereas 16 Hz AM modulated irradiation leads to significant increased efflux rates at SAR values of 0.30 and 0.15 mW/kg respectively. The other SAR values used in this study did not alter the calcium efflux.

Study character:

Study funded by

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