75 Wistar rats were randomly assigned to five groups: 1) sham exposure, 2) 4 h exposure, sacrificed immediately thereafter, 3) 4 h exposure, sacrificed 72 h thereafter, 4) 14 days of exposure, sacrificed immediately thereafter, and 5) 14 days of exposure, sacrificed 72 h thereafter. Blood samples were taken directly after sacrificing and analyzed.
|Setup||A pair of Helmholtz coils set with winding surrounded in a plexi-glass frame. Through a variable transformer the coils were connected to a 220 V AC power supply. The centrally horizontal magnetic field was homogenous in a plexi-glass cage.To adjust the frequency and intensity, the coils were linked to a waveform generator.|
|Sham exposure||A sham exposure was conducted.|
|Additional info||Sham exposure group was placed in the same cage though the coils were turned off, being exposed to the local geomagnetic field (B-field, horizontal component = 0.018 mT, B-field vertical component = 0.022 mT, B-field total = 0.023 mT and B-field alternating current < 0.002 mT).|
The results of all measured parameters of groups 2-5 were compared to the results of the sham exposure (group 1), respectively. A significantly higher paraoxonase enzyme activity, higher levels of conjugated diens, high density lipoprotein and free fatty acids as well as a significantly lower total antioxidative capacity could be observed in group 2 directly after the 4 h exposure. However, 72 h after the 4 h exposure (group 3), no significant alterations could be observed.
For group 4, significant changes of parameters comparable to the results of group 2 could be observed directly after 14 days of exposure, but additionally the level of malondialdehyde was significantly higher. 72 h after the 14-days exposure, the paraoxonase enzyme activity and the level of malondialdehyde were significantly higher and the total antioxidative capacity significantly lower (group 5).
The authors conclude that already a single exposure to a 60 Hz magnetic field with 0.5 mT has significant effects on factors in rat blood which can provoke atherosclerosis. However, these effects are reversible. The effects of a chronic exposure seem to be even more distinct and tend to be not reversible.