Study type: Medical/biological study (experimental study)

Microwave irradiation and in vitro release of enzymes from hepatic lysosomes med./bio.

By: Galvin MJ, Parks DL, McRee DI
Published in: Radiat Environ Biophys 1980; 18 (2): 129-136
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Aim of study (acc. to author)

To investigate the effects of microwave exposure on lysosomes.

Background/further details

Lysosomes were isolated from giunea pig liver tissue. The integrity of the lysosomal membrane was determined by measuring the release of two lysosome specific enzymes, β-glucuronidase and cathepsin D.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: CW
Exposure duration: continuous for 90 min
neutral medium (pH = 7.3)
Exposure 2: 2.45 GHz
Modulation type: CW
Exposure duration: continuous for 60 min
acidic medium (pH = 5.0)

Exposure 1

Main characteristics
Frequency 2.45 GHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 90 min
Additional info neutral medium (pH = 7.3)
Modulation
Modulation type CW
Exposure setup
Exposure source
Chamber The waveguide chamber was filled with distilled water (circulated and maintained at 37 °C) and matched to air by a quarter-wavelength dielectric plate (reflected power below 5%).
Setup The sample tubes of 1.06 cm inner and 1.36 cm outer diameter containing 4.2 ml of cell suspension (pH = 7.3) were located in the center of the waveguide parallel to the electric field. The exposed sample tube was placed against the dielectric plate, and the control was placed 9.5 cm away (five times the penetration depth), so it received no irradiation.
Sham exposure A sham exposure was conducted.
Additional info The maximum temperature difference between exposed and control suspension was 0.2 °C. The suspensions were stirred by small magnetic stirrers inserted in the portion of the tubes extending below the waveguide. A resulting magnetic field intensity of approximately 0.1 nT measured just above the stirrer using a circular loop was considered not to have any effect.
Parameters
Measurand Value Type Method Mass Remarks
SAR 10 mW/g mean measured - ±3%
SAR 50 mW/g mean measured - ±3%
SAR 100 mW/g mean measured - ±3%
Additional parameter details

The SARs indicated are the average values measured in samples stirred at 200 rpm to reduce temperature variations [Livingston et al., 1979].

Measurement and calculation details

SARs were determined from initial-heating, time-temperature profiles [McRee, 1974] for both non-stirred and stirred suspensions with the water not circulating using high power levels and a 1-mm non-interacting probe. For the non-stirred condition, the measured SARs agreed within ±10% with the results of power loss measurements [Chou at al., 1978; Johnson et al., 1972].

Exposure 2

Main characteristics
Frequency 2.45 GHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 60 min
Additional info acidic medium (pH = 5.0)
Modulation
Modulation type CW
Exposure setup
Exposure source
Setup acidic medium (pH = 5.0)
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 10 mW/g mean measured - ±3%
SAR 50 mW/g mean measured - ±3%
SAR 100 mW/g mean measured - ±3%

Reference articles

  • Livingston G et al. (1979): Comparative effects of water-bath- and microwave-induced hyperthermia on survival of Chinese hamster ovary (CHO) cells
  • Chou CK et al. (1978): Effects of electromagnetic fields on isolated nerve and muscle preparations
  • McRee DI (1974): Determination of the absorption of microwave radiation by a biological specimen in a 2450 MHz microwave field
  • 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:
  • after exposure

Main outcome of study (acc. to author)

The results reveal that microwave exposure has no effect on the lysosomal membrane as indicated by the unaltered release of specific enzymes compared to unexposed control probes.

Study character:

Study funded by