To study the effects of static electric fields on the spleen of mice.
With the development of high-voltage direct current (HVDC) power lines, the impact of static electric fields in the vicinity of these power lines on health has attracted public concern. With the increase of HVDC power lines, the authors deemed it necessary to study the effects of static electric fields on spleen. The spleen was investigated because of its role in activating and controlling the immune response.
68 mice were randomly divided into a control group (n=34) and an exposure group (n=34). The oxidative stress indices in the spleens of mice were determined after the exposure of 7, 14, and 21 days, respectively (n=10 mice per group). The cellular ultrastructure of the spleens was investigated after 21 days (n=4 mice per group).
| Exposure | Parameters |
|---|---|
|
Exposure 1:
Exposure duration:
continuously for 21 days
|
|
Temperature and humidity were maintained at 22 ± 2°C and 50~60%. Mice were raised in plastic buckets (35 cm × 25 cm × 46 cm). Temperature, humidity, noise, and ventilation inside the buckets of exposure group were the same as those inside the buckets of the control group. The electric potential of the mouth of the water bottle was about 2.3 kV. The plastic bucket was an insulating medium, i.e. there was an insulation between the mice in the bucket and the grounded lower plate. Therefore, the electric potential would not cause micro-discharges, according to the authors.
| Frequency | |
|---|---|
| Type | |
| Exposure duration | continuously for 21 days |
| Exposure source | |
|---|---|
| Setup | Exposure device was composed of a controller, a booster system, and upper and lower plates. The diameter of the two plates was 1 m. The plastic buckets of the control group were placed on the ground below the lower plate. The theoretical strength of the static electric field between the lower plate and the ground was 0 kV/m because the lower plate was grounded. The plastic buckets of the exposure group were also placed on the lower plate and exposed to the static electric field. |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 56.3 kV/m | - | - | - | 56.3 kV/m is 2.3 times of the limit value in China |
The data showed that the static electric field exposure of 21 days significantly increased the malondialdehyde level, the enzyme activities of superoxide dismutase, calcineurin, nitric oxide synthase, and the mRNA expression levels of tumor necrosis factor-α and nuclear factor kappa B in the spleen and caused the separation of nucleus and nuclear membrane, the disappearance of mitochondrial membrane, and the deficiency of mitochondrial cristae in splenic lymphocytes.
The authors concluded that the static electric field could induce oxidative stress of the spleen by increasing the enzyme activity of nitric oxide synthase. Oxidative stress could further cause ultrastructural changes of splenic lymphocytes. Moreover, oxidative stress could cause the increase of the mRNA expression levels of tumor necrosis factor-α and tumor nuclear factor kappa B, which contributed to the occurrence of spleen inflammation.
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