Experiments were conducted on healthy rats and rats with an experimentally induced inflammation (injection of Complete Freund's Adjuvant into paw), together with or without the opioid tramadol as co-exposure. Possible relations of these factors to an electromagnetic field were observed in a former study (Bodera et al. 2013).
Rats were divided into the following groups (n=8 each):
Healthy rats: 1) exposure to the electromagnetic field and intraperitoneal sham injection (water), 2) sham exposure and injection of 20 mg/kg tramadol prior to exposure, 3) exposure and injection of tramadol, 4) sham exposure and sham injection (control group for healthy rats).
Rats with inflammation: 5) exposure and sham injection, 6) sham exposure and injection of tramadol, 7) exposure and injection of tramadol, 8) sham exposure and sham injection (control groups for rats with inflammation).
Modulation type: pulsed
Exposure duration: continuous for 15 minutes/day for 5 days
|Pulse width||0.577 ms|
|Duty cycle||50 %|
|Repetition frequency||877 Hz|
the fundamental unit of time in this TDMA scheme (a burst period) lasts for 15/26 ms (approximately 0.577 ms); eight burst periods are grouped into a TDMA frame (120/26 ms or approximately 4.615 ms), which forms the basic unit of a logical channel
|Chamber||plexiglass containers (218 mm length and width, 134 mm height, wall thickness 5 mm); each rat occupied 1/2 of the space of the container, separated by a transparent plastic wall (5 mm in thickness) and could not move inside this space (? SAR calculated for different positions)|
|Setup||animals were placed in pairs in plexiglass containers in 1 m (or 1.2 m?) distance to the antenna; the propagation vector of the incident wave was parallel to the long axis of the animal's body|
|Sham exposure||A sham exposure was conducted.|
In both, healthy rats and rats with inflammation, exposure to the electromagnetic field (groups 1 and 5) resulted in significantly increased lipid peroxidation in the blood and in the brain compared to the respective control groups (groups 4 and 8). In groups with a combination of exposure to the electromagnetic field and tramadol (groups 3 and 7), a significant increase of lipid peroxidation in the blood, in the brain and in the kidneys in comparison to the control group was observed.
A treatment of healthy rats with tramadol alone (group 2) led to significant increases of lipid peroxidation in the blood, in the brain and in the kidneys compared to the respective control group, whereas a tramadol treatment of rats with inflammation resulted in a significant increase of lipid peroxidation in the kidneys and a significant reduction in the blood.
In the liver, no significant differences were found between the groups. Moreover, no significant differences were found between healthy rats and rats with inflammation with the same treatment.
The authors conclude that exposure of rats to a 1800 MHz electromagnetic field might increase lipid peroxidation in brain, blood and kidneys and that co-exposure to tramadol could show a synergistic effect.