Medical/biological study (experimental study)

Effects of 940 MHz EMF on bioluminescence and oxidative response of stable luciferase producing HEK cells med./bio.

By: Sefidbakht Y, Moosavi-Movahedi AA, Hosseinkhani S, Khodagholi F, Torkzadeh-Mahani M, Foolad F, Faraji-Dana R

Published in: Photochem Photobiol Sci 2014; 13 (7): 1082-1092

Aim of study (acc. to author)

The effects of an acute exposure of transgenic human embryonic kidney cells to a 940 MHz electromagnetic field on the luciferase enzyme activity and oxidative stress should be investigated.

Background/further details

The firefly luciferase gene was transfected into human embryonic kidney cells as the enzyme activity of luciferase is a sensitive marker for cellular stress.
Cells were either sham exposed or exposed for up to 90 minutes. All results represent means of 3 repeated experiments with 3 measurements, respectively.

Endpoint

cell function: luciferase enzyme activity and oxidative stress

Exposure

- 940 MHz
- mobile communications
- mobile phone

Exposure	Parameters
Exposure 1: 940 MHz Exposure duration: continuous for up to 90 minutes	SAR: 0.09 W/kg mean electric field strength: 10 V/m effective value (across petri dish) power: 1 W (input power)

Exposure 1

Main characteristics

Frequency	940 MHz
Type	electromagnetic field
Exposure duration	continuous for up to 90 minutes

Exposure setup

Exposure source	waveguide
Chamber	cell monolayer inside a 35 mm petri dish
Setup	waveguide unit consisted of an aluminum box (60 x 17 x 17 cm) with one probe at each end generating the field; 4 discs (stubs) were used for impedance matching; reactangular waveguide was placed in an incubator and equipped with two fans working in opposite directions at both ends for temperature control (37 ± 0.3°C in incubator; temperature change in dishes was 0.07±0.03 °C (range 0.02-0.1°C) during exposure); field inhomogeneity was below 30%
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	0.09 W/kg	mean	calculated	-	-
electric field strength	10 V/m	effective value	-	-	across petri dish
power	1 W	-	-	-	input power

Reference articles

Sefidbakht Y et al. (2013): Effects of 940 MHz EMF on Luciferase solution: structure, function, and dielectric studies

Exposed system:

intact cell/cell culture
HEK 293T cells (human embryonic kidney cells) transfected with luciferase gene

Methods Endpoint/measurement parameters/methodology

cell function: luciferase enzyme activity (after 15, 30, 45, 60 and 90 minutes; measurement of bioluminescence)
cell viability/cell division/proliferation: apoptosis (after 15, 30, 45, 60 and 90 minutes; enzyme activity of caspase-3 and -7; bioluminescence assay)
oxidative stress: enzyme activities of superoxide dismutase and catalase, content of reduced glutathione, lipid peroxidation (content of malondialdehyde) (after 15, 30, 45 and 60 minutes; spectrophotometry), content of reactive oxygen species (after 5, 15, 30 and 45 minutes; reaction with dichlorofluorescein, fluorophotometry and flow cytometry)

Investigated system:

isolated bio./chem. substance
cell lysate, proteins

Time of investigation:

during exposure
after exposure

Main outcome of study (acc. to author)

The luciferase enzyme activity was significantly decreased after 30 and 45 minutes and significantly increased after 60 minutes of exposure compared to sham exposure.
The reactive oxygen species content was significantly increased after 15, 30 and 45 minutes of exposure compared to sham exposure. The enzyme activity of superoxide dismutase was significantly increased after 30 and 45 minutes of exposure compared to sham exposure. The enzyme activity of catalase was significantly increased after 15, 30, 45 and 60 minutes of exposure compared to sham exposure. The content of reduced glutathione was significantly increased after 45 minutes of exposure, whereas the content of malondialdehyde was significantly reduced after 45 minutes compared to sham exposure.
The enzyme activity of caspase 3 and 7 was significantly increased after 45 and 90 minutes, but not after 60 minutes of exposure compared to sham exposure, showing no distinct indication for apoptosis.
The authors conclude, that an acute exposure of transgenic human embryonic kidney cells to a 940 MHz electromagnetic field could cause oxidative stress which is followed by an anti-oxidative response, what is represented by the luciferase enzyme activity.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Centre of Excellence in Biothermodynamics, University of Tehran, Tehran, Iran
Iran National Science Foundation (INSF)
Iran Society of Biophysical Chemistry (ISOBC)
Iran's National Elites Foundation (INEF)
University of Tehran, Iran

Kang KA et al. (2014): Effects of combined radiofrequency radiation exposure on levels of reactive oxygen species in neuronal cells
Sefidbakht Y et al. (2013): Effects of 940 MHz EMF on Luciferase solution: structure, function, and dielectric studies
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Hong MN et al. (2012): Effects of 837 and 1950 MHz radiofrequency radiation exposure alone or combined on oxidative stress in MCF10A cells
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