Study type: Medical/biological study (experimental study)

Slow and rapid responses to CW and pulsed microwave radiation by individual Aplysia Pacemakers med./bio.

By: Seaman RL, Wachtel H
Published in: J Microw Power 1978; 13 (1): 77-86
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Aim of study (acc. to author)

In order to study the effetcs of microwaves on excitable cells, the resting potentials of individual invertebrate neurons during microwave irradiation were observed. Responses of neurons of Aplysia to irradiation with those changing temperature and to injected currents were compared.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1.5 GHz
Modulation type: pulsed
Exposure duration: 2 to 3 min
  • SAR: 1 mW/g minimum (unspecified) (400 mW/g max value)
Exposure 2: 2.45 GHz
Modulation type: pulsed
Exposure duration: 2 to 3 min
  • SAR: 1 mW/g mean (unspecified) (400 mW/g max value)
Exposure 3: 1.5 GHz
Modulation type: CW
Exposure duration: 2 to 3 min
  • SAR: 7 mW/g mean (unspecified) (291 mW/g max value)
Exposure 4: 2.45 GHz
Modulation type: CW
Exposure duration: 2 to 3 min
  • SAR: 7 mW/g mean (unspecified) (291 mW/g max value)

Exposure 1

Main characteristics
Frequency 1.5 GHz
Exposure duration 2 to 3 min
Modulation
Modulation type pulsed
Additional info

Pulses of duration 0.5 µs to 10 µs at repetition rates of 1000/s to 5000 /s with rise time less than 0.1 µs were used.
Exposure setup
Exposure source
  • stripline fixture.
Setup Chamber containing ganglion was placed between the center conductor and the outer ground conductor of the stripline fixture.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1 mW/g minimum calculated unspecified 400 mW/g max value

Exposure 2

Main characteristics
Frequency 2.45 GHz
Exposure duration 2 to 3 min
Modulation
Modulation type pulsed
Additional info

Pulses of duration 0.5 µs to 10 µs at repetition rates of 1000/s to 5000 /s with rise time less than 0.1 µs were used.
Exposure setup
Exposure source
  • same setup as exposure 1
  • stripline fixture.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1 mW/g mean calculated unspecified 400 mW/g max value

Exposure 3

Main characteristics
Frequency 1.5 GHz
Exposure duration 2 to 3 min
Modulation
Modulation type CW
Exposure setup
Exposure source
  • same setup as exposure 1
  • stripline fixture.
Parameters
Measurand Value Type Method Mass Remarks
SAR 7 mW/g mean calculated unspecified 291 mW/g max value

Exposure 4

Main characteristics
Frequency 2.45 GHz
Exposure duration 2 to 3 min
Modulation
Modulation type CW
Exposure setup
Exposure source
  • same setup as exposure 1
  • stripline fixture.
Parameters
Measurand Value Type Method Mass Remarks
SAR 7 mW/g mean calculated unspecified 291 mW/g max value

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)

Irradiation for 2 to 3 minutes at an SAR of only a few mW/g was capable of changing the firing rate of some pacemakers. Two types of responses were revealed. The response that was seen in all neurons developed slowly and reached a steady state in one to three minutes. The other response was seen in a few neurons and occured within five seconds from the onset of exposure. Similar responses were revealed for two microwave frequencies (1.5 and 2.45 GHz). Pulsed irradiation induced rapid changes of firing rate more readily than did CW irradiation at the same SAR.
Since all of the responses are not readily explained by general heating of the preparation, alternate mechanisms are suggested for the revealed effects.

Study character:

Study funded by

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