Study type: Medical/biological study (experimental study)

Exposure of nerve growth factor-treated PC12 rat pheochromocytoma cells to a modulated radiofrequency field at 836.55 MHz: effects on c-jun and c-fos expression med./bio.

By: Ivaschuk OI, Jones RA, Ishida-Jones T, Haggren W, Adey WR, Phillips JL
Published in: Bioelectromagnetics 1997; 18 (3): 223-229
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Aim of study (acc. to author)

To determine whether exposure of NGF (nerve growth factor)-treated PC12 cells to an athermal modulated radiofrequency field at 836.55 MHz altered the expression of the immediate early genes encoding c-jun and c-fos.

Background/further details

NGF is required for the survival and development of neuronal populations in both the central and peripheral nervous system, and it influences the phenotypic characteristics of neurons in vivo and in vitro.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 836.55 MHz
Modulation type: pulsed
Exposure duration: intermittent, 20 min on/off, for 20, 60 and 100 min
  • power: 0.17 W average over time (0.017, 0.17 and 1.7 W)
  • power density: 0.3 mW/cm² average over time (0.03, 0.3 and 3 mW/cm²)
  • power density: 0.9 mW/cm² cf. remarks (0.09, 0.9 and 9 mW/cm² slot average)
  • SAR: 2.6 µW/g cf. remarks (± 1.9 µW/g slot average at 0.9 mW/cm²)

Exposure 1

Main characteristics
Frequency 836.55 MHz
Type
Charakteristic
  • guided field
Exposure duration intermittent, 20 min on/off, for 20, 60 and 100 min
Modulation
Modulation type pulsed
Pulse width 6.67 ms
Duty cycle 33 %
Repetition frequency 50 Hz
Additional info

TDMA with π/4 DQPSK according to NADC standard
Exposure setup
Exposure source
Chamber Two TEM cells of square cross section, one powered and one for sham exposure, were placed in a water-jacketed incubator maintained at 37 °C and 5% CO2.
Setup Cells were seeded on 100 mm Petri dishes with 20 ml of medium (depth of 3 mm). In most experiments, two stacks of two dishes each were placed centrally on the septum in each TEM cell, and in a few experiments, dishes were placed on both the septum and the bottom of the TEM cells in an identical fashion. The E-field was normal to the Petri dishes.
Additional info The transmitter was switched on/off at 20 min intervals for total exposures of 20, 40, and 60 min (20, 60, and 100 min total incubation times).
Parameters
Measurand Value Type Method Mass Remarks
power 0.17 W average over time measured - 0.017, 0.17 and 1.7 W
power density 0.3 mW/cm² average over time measured - 0.03, 0.3 and 3 mW/cm²
power density 0.9 mW/cm² cf. remarks measured - 0.09, 0.9 and 9 mW/cm² slot average
SAR 2.6 µW/g cf. remarks calculated - ± 1.9 µW/g slot average at 0.9 mW/cm²
Additional parameter details

Local static magnetic field in the incubator was 31 ± 12 µT at 9 ± 28° inclination. Ambient 60 Hz magnetic field was 0.13 ± 0.02 µT rms and 0.20 ± 0.04 µT rms at the location of the exposure and sham exposure cell, respectively.

Measurement and calculation details

The RF output from the transmitter passed through an in-line wattmeter to a 1:4 splitter one port of which was used for monitoring RF power levels via bidirectional coupler, attenuator and a diode detector. The forward power port of the coupler was connected to a power meter through a thermistor mount. RF power at the TEM cell input was measured using a power meter and power sensor and matched attenuator. The power densities were based on measured input powers and the dimensions of the TEM cell. Dosimetric considerations also used in this study are presented in more detail in the reference article. The experimental conditions were simulated using the MAFIA simulation tool to calculate slot average SAR values.

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

No change in c-fos transcript levels were detected after 20 min exposure at each field intensity (20 min was the only time period at which the c-fos transcript could be detected consistently). Transcript levels for c-jun were altered only after 20 min exposure (9mW/cm²).

Study character:

Study funded by

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