To examine whether an adaptive response can be induced in mice and rats which were pre-exposed to microwaves in order to increase the resistance to lethal doses of gamma rays (challenge dose).
Adaptive response: It is known that different cell types that were exposed to an extremely small adaptation dose of a genotoxic agent are less susceptible to the induction of a genetic damage when given a higher challenge dose of the same or similar genotoxic agent.
Two experiments were performed. In the first experiment, 110 mice were divided into 8 groups (13-15 mice per group) and received different combinations of exposure to microwaves (MW) as an adaptive dose, low dose gamma radiation (LDGR) as an adaptive dose and lethal dose gamma radiation (LD) as a challenge dose: 1.) control group,2.) MW, 3.) LDGR, 4.) MW, LDGR, 5.) MW, LD, 6.) LDGR, LD, 7.) MW, LDGR, LD and 8.) LD. In the second experiment, 30 rats were divided into 2 groups (15 rats per group): 1.) 1.) MW, LD (8 Gy) and 2.) LD (8 Gy).
| Frequency | 900 MHz |
|---|---|
| Type | |
| Exposure duration | mice: 6 h/day for 5 days; rats: 6 h/day for 6 days (or 4 days?, contradictory information) |
| Modulation type | pulsed |
|---|---|
| Pulse width | 463 µs |
| Duty cycle | 12.5 % |
| Repetition frequency | 217 Hz |
| Exposure source |
|
|---|---|
| Distance between exposed object and exposure source | 10 cm |
| Chamber | animals were immobilized in plastic restrainers |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| power | 2 W | - | - | - | - |
In the first experiment, mice were examined after 6 [12] days. The survival rate of the mice in the control group (group 1) was 95 % [95%] and hence identical with the survival rate of microwave exposed mice (group 2). Mice exposed to LDGR (group 3) had a survival rate of 85 % [85 %], while 100 % [100 %] of the mice survived that were exposed to a combination of microwaves and LDGR (group 4). The survival rate of mice which were exposed to microwaves and LD (group 5) was 80 % [60 %] and of mice which were exposed to LDGR and LD (group 6) it was 90 % [90 %], while 90 % [80 %] of the mice survived that were exposed to microwaves, LDGR and LD (group 7). Mice not pre-treated and directly exposed to LD (group 8) had a survival rate of 60 % [10 %].
In the second experiment, rats were examined after 10 [20; 30] days. In rats pre-exposed to microwaves before LD, a survival rate of 100 % [100 %; 100 %] was observed, whereas in rats not pre-treated and directly exposed to LD the survival rate was 100 % [86.6 %; 53.3 %].
The authors conclude that exposure of mice and rats to microwaves could induce an adaptive response to a lethal dose of gamma radiation.
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