Study type: Medical/biological study (experimental study)

Local exposure of the rat cortex to radiofrequency electromagnetic fields increases local cerebral blood flow along with temperature. med./bio.

Published in: J Appl Physiol 2011; 110 (1): 142-148

Aim of study (acc. to author)

To study reproducible responses to local radiofrequency exposure in the parietal cortex of anesthetized rats and to determine their dependence on exposure intensity.

Background/further details

Rats were exposed under anesthesia. A "closed cranial window" was implanted into the parietal region.
The rat cortex was locally exposed to different SAR values in the target (parietal) area (n=7 in each group).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1,950 MHz
Exposure duration: continuous for 18 min
  • SAR: 10.5 W/kg average over mass (cf. remarks) (averaged over 4.04 mg (parietal target area); brain 6.14 W/kg; whole body 0.31 W/kg)
  • SAR: 40.3 W/kg average over mass (cf. remarks) (averaged over 4.04 mg (parietal target area); brain 23.5 W/kg; whole body 1.18 W/kg)
  • SAR: 130 W/kg average over mass (cf. remarks) (averaged over 4.04 mg (parietal target area); brain 75.8 W/kg; whole body 3.8 W/kg)
  • SAR: 263 W/kg average over mass (cf. remarks) (averaged over 4.04 mg (parietal target area); brain 153 W/kg; whole body 7.69 W/kg)

Exposure 1

Main characteristics
Frequency 1,950 MHz
Type
Exposure duration continuous for 18 min
Exposure setup
Exposure source
Setup rat placed in an anechoic chamber and fixed in an acrylic stereotaxis apparatus with the antenna positioned 4 mm over the parietal bone
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
SAR 10.5 W/kg average over mass estimated cf. remarks averaged over 4.04 mg (parietal target area); brain 6.14 W/kg; whole body 0.31 W/kg
SAR 40.3 W/kg average over mass estimated cf. remarks averaged over 4.04 mg (parietal target area); brain 23.5 W/kg; whole body 1.18 W/kg
SAR 130 W/kg average over mass estimated cf. remarks averaged over 4.04 mg (parietal target area); brain 75.8 W/kg; whole body 3.8 W/kg
SAR 263 W/kg average over mass estimated cf. remarks averaged over 4.04 mg (parietal target area); brain 153 W/kg; whole body 7.69 W/kg

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

All parameters except for the calf hypodermis temperature increased significantly in exposed animals compared with sham exposed rats during an exposure of 18 minutes. Local cerebral blood flow and temperature in the parietal target area and rectum depend markedly on the intensity of radiofrequency exposure. Furthermore, local cerebral blood flow elevation was significantly correlated with both temperature rise in the parietal target region and rectum after an exposure of 18 minutes. The local cerebral blood flow elevation seemed to be elevated by the rise in target temperature, but not by that of the rectal temperature, in the early part of radiofrequency exposure or at low-intensity radiofrequency exposure.
These data suggest that local radiofrequency exposure of the rat cortex drives a regulation of cerebral blood flow accompanied by a local temperature rise. These findings may be helpful for discussing physiological changes in the cortex region which is locally exposed to radiofrequency.

Study character:

Study funded by

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