Medical/biological study (experimental study)

50 Hz alternating extremely low frequency magnetic fields affect excitability, firing and action potential shape through interaction with ionic channels in snail neurones med./bio.

By: Moghadam MK, Firoozabadi SM, Janahmadi M

Published in: Environmentalist 2008; 28 (4): 341-347

Download citation in RIS format

Aim of study (acc. to author)

To investigate if 50 Hz magnetic fields have an effect on the neuronal excitability and firing responses of neurons.

Background/further details

All experiments were performed on a single identified neuron (F1) located in the visceral ganglion of the snail.

Endpoint

cell function: resting potentials, spontaneous and evoked action potentials of snail neurons

Exposure

- 50/60 Hz
- magnetic field

Exposure	Parameters
Exposure 1: 50 Hz Modulation type: pulsed Exposure duration: 2 times 5 min	magnetic flux density: 0.8 mT magnetic flux density: 2 mT

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Waveform	rectangular
Exposure duration	2 times 5 min

Modulation

Modulation type	pulsed
Pulse width	10 ms
Rise time	10 ms
Fall time	10 ms
Duty cycle	50 %
Pulse type	biphasic

Exposure setup

Exposure source	coil(s)
Setup	coil with an inner diameter of 8 cm and 8500 turns of 0.75 mm wire, covered with a resin coating; experiments performed in a Faraday cage
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	0.8 mT	-	-	-	-
magnetic flux density	2 mT	-	-	-	-

Exposed system:

intact cell/cell culture
snail neurons (Helix aspersa)

Methods Endpoint/measurement parameters/methodology

cell function: resting membrane potentials, spontaneous and evoked action potentials (current clamp method)

Investigated system:

intact cell/cell culture

Time of investigation:

before exposure
after exposure

Main outcome of study (acc. to author)

Exposure to 50 Hz magnetic fields at 2 mT or 0.8 mT resulted in an increase in the peak amplitude of action potential and after hyperpolarization potential in a time dependent manner (maximum effect between 16 min [2 mT] and 45 min [0.8 mT] after exposure). Both magnetic field intensities decreased also the firing rate (maximum reduction between 12 min [2 mT] and 45 min [0.8 mT] after exposure) and the duration of action potential (maximum reduction 20 min after exposure).
The data suggest that 50 Hz magnetic fields at both intensities may have inhibitory effects on the electrophysiological behaviour of neuronal cells and underlying ion channel currents.

Study character:

medical/biological study
experimental study
full/main study

Zheng Y et al. (2019): Effects of exposure to extremely low frequency electromagnetic fields on hippocampal long-term potentiation in hippocampal CA1 region
Komaki A et al. (2014): Effects of exposure to an extremely low frequency electromagnetic field on hippocampal long-term potentiation in rat
Azanza MJ et al. (2013): Synchronization dynamics induced on pairs of neurons under applied weak alternating magnetic fields
Balassa T et al. (2013): Changes in synaptic efficacy in rat brain slices following extremely low-frequency magnetic field exposure at embryonic and early postnatal age
Moghadam MK et al. (2011): Effects of weak environmental magnetic fields on the spontaneous bioelectrical activity of snail neurons
Nikolic LM et al. (2010): Effect of alternating the magnetic field on phosphate metabolism in the nervous system of Helix pomatia
Varro P et al. (2009): Changes in synaptic efficacy and seizure susceptibility in rat brain slices following extremely low-frequency electromagnetic field exposure
Partsvania B et al. (2008): Extremely low-frequency magnetic fields effects on the snail single neurons
Park JH et al. (2006): Observation of the fast response of a magnetic resonance signal to neuronal activity: a snail ganglia study
Marchionni I et al. (2006): Comparison between low-level 50 Hz and 900 MHz electromagnetic stimulation on single channel ionic currents and on firing frequency in dorsal root ganglion isolated neurons
Radman T et al. (2006): Amplification of small electric fields by neurons; implications for spike timing
Perez-Bruzon RN et al. (2004): Neurone bioelectric activity under magnetic fields of variable frequency in the range of 0.1 - 80 Hz
Azanza MJ et al. (2002): Evidence of synchronization of neuronal activity of molluscan brain ganglia induced by alternating 50 Hz applied magnetic field
Calvo AC et al. (1999): Synaptic neurone activity under applied 50 Hz alternating magnetic fields
Azanza MJ et al. (1996): Isolated neuron amplitude spike decrease under static magnetic fields
Azanza MJ (1989): Steady magnetic fields mimic the effect of caffeine on neurons