Study type: Medical/biological study (experimental study)

Thermal bradycardia during radiofrequency irradiation. med./bio.

Published in: Physiol Chem Phys Med NMR 1983; 15 (5): 429-434

Aim of study (acc. to author)

To study if any heart rate or blood pressure changes occur during intermittent exposure to radiofrequency irradiation in rats, and to determine if parasympathetic blockade due to atropine has any effect on these changes or on thermal responses.



Exposure Parameters
Exposure 1: 2.8 GHz
Modulation type: pulsed
Exposure duration: intermittent, about 7-10 min on/9-14 min off, for 2 x 3 cycles, see below

Exposure 1

Main characteristics
Frequency 2.8 GHz
Exposure duration intermittent, about 7-10 min on/9-14 min off, for 2 x 3 cycles, see below
Modulation type pulsed
Pulse width 2 µs
Repetition frequency 500 Hz
Exposure setup
Exposure source
Setup Anaesthetized animals were exposed in the H-orientation with their long axis parallel to the H-field.
Additional info Animals were exposed until their colonic temperature rose to 39.5°C. Exposure was repeated when the temperature returned to 38.5°C. This procedure was repeated for three cycles. Then, at 38.5°C, either atropine sulphate or saline was administered i.p. After a 15 min interval, exposure was resumed for another three (or four?) cycles [Heinmets, 1982].
Measurand Value Type Method Mass Remarks
power density 60 mW/cm² mean measured - -
SAR 14 W/kg mean estimated - [Durney et al., 1978]

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

During an initial irradiation period to raise colonic temperature to 39.5°C, heart rate decreased significantly. Intermittent exposure to irradiation, which resulted in 1°C colonic temperature changes, did not significantly affect heart rate or mean arterial blood pressure, before or after atropine administration. The time courses of these 1°C temperature changes were not changed significantly by atropine. Following administration of atropine, the thermal bradycardia during the initial heating period was still evident. It is possible that the bradycardia is a consequence of a general reduction in metabolism, which is observed also during environmental heat exposure.

Study character:

Study funded by