Medical/biological study (experimental study)

Exposure to a 50 Hz magnetic field at 100 µT exerts no DNA damage in cardiomyocytes med./bio.

By: Wang Y, Liu X, Zhang Y, Wan B, Zhang J, He W, Hu D, Yang Y, Lai J, He M, Chen C

Published in: Biol Open 2019; 8 (8): bio041293

Aim of study (acc. to author)

The possible genotoxic effects of a 50 Hz magnetic field exposure in cardiomyocytes should be investigated in vitro and in vivo.

Background/further details

For the in vitro experiments, human cardiomyocytes were divided into the following groups: 1) continuous exposure to the magnetic field, 2) intermittent exposure to the magnetic field as well as a control group and a sham exposure group. Moreover, for cell cycle analyses and comet assay, positive controls were used. Experiments were repeated three times.
For the in vivo experiments, 20 rats were randomly and evenly divided into an exposure (group 3) and a sham exposure group. All animals were sacrificed the day after the last exposure.

Endpoint

genotoxicity/mutation: DNA damage and related parameters

Exposure

- 50/60 Hz
- magnetic field

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: continuous for 1 hour in vitro	magnetic flux density: 100 µT
Exposure 2: 50 Hz Exposure duration: intermittent (15 min field on / 15 min field off) for 75 min in vitro	magnetic flux density: 100 µT
Exposure 3: 50 Hz Exposure duration: continuous for 15 hours/day for 7 days in vivo	magnetic flux density: 100 µT

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Exposure duration	continuous for 1 hour
Additional info	in vitro

Exposure setup

Exposure source	coil(s)
Setup	a pair of parallel coils (200 cm × 70 cm × 200 cm, L × W × H; horizontal bronze wires were used to generate a vertical magnetic field; in order to generate the uniform magnetic field, the wiring ratio of the five coils was 2:1:1:1:2 and the 3% uniformity area for each floor was 150 cm × 50 cm (L × W); the wires were fixed tightly to the framework in order to decrease the vibration and the noise; temperature during exposure was 22°C
Sham exposure	A sham exposure was conducted.
Additional info	sham-exposure system was exactly the same system as the exposure system but without power; it was located in a separate and non-adjacent room with the same environmental conditions

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	100 µT	-	-	-	-

Exposure 2

Main characteristics

Frequency	50 Hz
Type	magnetic field
Exposure duration	intermittent (15 min field on / 15 min field off) for 75 min
Additional info	in vitro

Exposure setup

Exposure source	same setup as exposure 1

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	100 µT	-	-	-	-

Exposure 3

Main characteristics

Frequency	50 Hz
Type	magnetic field
Exposure duration	continuous for 15 hours/day for 7 days
Additional info	in vivo

Exposure setup

Exposure source	same setup as exposure 1
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	100 µT	-	-	-	-

Reference articles

Zhou L et al. (2016): The effects of a 50-Hz magnetic field on the cardiovascular system in rats
Lai J et al. (2016): Effects of 100 µT extremely low frequency electromagnetic fields exposure on hematograms and blood chemistry in rats
Misakian M et al. (1993): Biological, physical, and electrical parameters for in vitro studies with ELF magnetic and electric fields: a primer

Exposed system:

intact cell/cell culture
human ventricular cardiomyocytes cell line (AC16)
animal
rat/Sprague Dawley
whole body

Methods Endpoint/measurement parameters/methodology

genotoxicity/mutation: in vitro tests: DNA damage (DNA single-strand breaks and double-strand breaks; alkaline comet assay)
cell viability/cell division/proliferation: in vitro tests: cell cycle analysis (0, 6 and 16 hours after exposure; propidium iodide stain, flow cytometry)
oxidative stress in in vitro tests: level of reactive oxygen species (dichlorofluorescein stain, flow cytometry) and level of reduced and oxidized glutathione (commercial kit, well plate reader)
molecular biosynthesis: in vitro tests: gene expression of Hsp70 and p53 (0, 1 and 3 hours after exposure; real-time RT-PCR); in vitro and in vivo tests: protein expression of Hsp70 and p53 (0, 1 and 3 hours after exposure in in vitro tests; Western blot)

Investigated system:

Time of investigation:

after exposure

Main outcome of study (acc. to author)

There were no statistically significant effects in any exposure group compared to the control groups or sham exposure groups.
The authors conclude that there were no indications of genotoxic effects of 50 Hz magnetic field exposure in cardiomyocytes in vitro and in vivo found.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

National Natural Science Foundation (NSFC), China
State Grid Corporation, China (SGCC)

Zhang Y et al. (2020): Examination of the Effect of a 50-Hz Electromagnetic Field at 500 μT on Parameters Related With the Cardiovascular System in Rats
Zhou L et al. (2016): The effects of a 50-Hz magnetic field on the cardiovascular system in rats
Villarini M et al. (2013): Brain hsp70 expression and DNA damage in mice exposed to extremely low frequency magnetic fields: a dose-response study
Kiray A et al. (2013): The effects of exposure to electromagnetic field on rat myocardium
Kurian MV et al. (2012): Enhanced cell survival and diminished apoptotic response to simulated ischemia-reperfusion in H9c2 cells by magnetic field preconditioning
Elmas O et al. (2012): Effects of short-term exposure to powerline-frequency electromagnetic field on the electrical activity of the heart
Tayefi H et al. (2010): The effects of prenatal and neonatal exposure to electromagnetic fields on infant rat myocardium
George I et al. (2008): Myocardial function improved by electromagnetic field induction of stress protein hsp70
Jeong JH et al. (2005): Influence of exposure to electromagnetic field on the cardiovascular system
Tokalov SV et al. (2004): Weak electromagnetic fields (50 Hz) elicit a stress response in human cells
Ali FM et al. (2003): Effect of 50 Hz, 0.2 mT magnetic fields on RBC properties and heart functions of albino rats
Carmody S et al. (2000): Cytoprotection by electromagnetic field-induced hsp70: a model for clinical application
DiCarlo AL et al. (1999): Myocardial protection conferred by electromagnetic fields
Lin H et al. (1999): A magnetic field-responsive domain in the human HSP70 promoter
Lin H et al. (1998): Myc-mediated transactivation of HSP70 expression following exposure to magnetic fields
Goodman R et al. (1998): Magnetic field stress induces expression of hsp70
Han L et al. (1998): Application of magnetic field-induced heat shock protein 70 for presurgical cytoprotection
Lin H et al. (1997): Electromagnetic field exposure induces rapid, transitory heat shock factor activation in human cells
Goodman R et al. (1994): Increased levels of hsp70 transcripts induced when cells are exposed to low frequency electromagnetic fields
Korpinen L et al. (1993): Influence of 50 Hz electric and magnetic fields on the human heart
Willis RJ et al. (1984): Potential hazards of NMR imaging. No evidence of the possible effects of static and changing magnetic fields on cardiac function of the rat and guinea pig

Exposure to a 50 Hz magnetic field at 100 µT exerts no DNA damage in cardiomyocytes med./bio.

Aim of study (acc. to author)

Background/further details

Endpoint

Exposure

Exposure 1

Main characteristics

Exposure setup

Parameters

Exposure 2

Main characteristics

Exposure setup

Parameters

Exposure 3

Main characteristics

Exposure setup

Parameters

Reference articles

Methods Endpoint/measurement parameters/methodology

Main outcome of study (acc. to author)

Study funded by

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