Study type: Medical/biological study (experimental study)

Effects of continuous-wave, pulsed, and sinusoidal-amplitude-modulated microwaves on brain energy metabolism. med./bio.

Published in: Bioelectromagnetics 1985; 6 (1): 89-97

Aim of study (acc. to author)

To determine whether rat brain metabolism (reflected in brain ATP and creatine phosphate (CP)-concentration) is affected differentially by exposure to continuous wave (CW), pulsed, or sinusoidal amplitude modulated microwaves.

Background/further details

Brain temperatures of rats were maintained between -0.1 and -0.4°C from the preexposure temperature when subjected to as much as 20 mW/cm² CW, pulsed, or sinusoidal amplitude modulated 591 MHz exposure for 5 min.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 591 MHz
Modulation type: CW
Exposure duration: 5 min
Exposure 2: 591 MHz
Modulation type: AM
Exposure duration: 5 min
Exposure 3: 591 MHz
Modulation type: pulsed
Exposure duration: 5 min

Exposure 1

Main characteristics
Frequency 591 MHz
Exposure duration 5 min
Modulation
Modulation type CW
Exposure setup
Exposure source
Chamber Microstrip system
Setup Anesthetized rats were placed over the microstrip exposure system
Parameters
Measurand Value Type Method Mass Remarks
power density 10 mW/cm² mean measured - -
power density 20 mW/cm² mean measured - -
power density 13.8 mW/cm² mean measured - 13.25 mW/cm², 8 mW/cm², 6 mW/cm², 4.5 mW/cm², 3 mW/cm², 1.5 mW/cm² and 1 mW/cm²

Exposure 2

Main characteristics
Frequency 591 MHz
Exposure duration 5 min
Modulation
Modulation type AM
Modulation frequency 4–24 Hz
Additional info

Modulation frequencies used: 4 Hz, 8 Hz, 12 Hz, 16 Hz, 20 Hz, 24 Hz, 28 Hz and 32 Hz.

Exposure setup
Exposure source
Additional info Distance from source/object 2-3 mm
Parameters
Measurand Value Type Method Mass Remarks
power density 20 mW/cm² mean measured - -
power density 10 mW/cm² mean measured - -
power density 13.8 W/m² mean measured - 13.25 mW/cm², 8 mW/cm², 6 mW/cm², 4.5 mW/cm², 3 mW/cm², 1.5 mW/cm² and 1 mW/cm²

Exposure 3

Main characteristics
Frequency 591 MHz
Exposure duration 5 min
Modulation
Modulation type pulsed
Pulse width 5 µs
Additional info

250 or 500 pps

Exposure setup
Exposure source
  • same setup as exposure 1
  • Ailtech M125A MW generator and a Hewlett-Packard 8005A pulse generator
Distance between exposed object and exposure source 0.002 m
Parameters
Measurand Value Type Method Mass Remarks
power density 13.8 W/m² mean measured - 13.25 mW/cm², 8 mW/cm², 6 mW/cm², 4.5 mW/cm², 3 mW/cm², 1.5 mW/cm² and 1 mW/cm²
power density 20 mW/cm² mean measured - -
power density 10 mW/cm² mean measured - -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The pulse modulated and sinusoidal amplitude modulated (16 Hz) microwaves were not significantly different from CW irradiations in inducing increased NADH fluorescence and decreased ATP and CP concentrations. When the pulse modulation frequency was decreased from 500 to 250 pulses (per second) the average incident power density threshold for inducing an increase in brain NADH increased by a factor of 4, i.e. from about 0.45 to about 1.85 mW/cm². Since brain temperature did not increase, the microwave-induced increase in NADH and decrease in ATP and CP concentrations was not due to hyperthermia. This suggests a direct interaction mechanism. It is consistent with the hypothesis of microwave inhibition of mitochondrial electron transport chain function of ATP production.

Study character:

Study funded by

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