Medical/biological study (experimental study)

Effects of weak environmental magnetic fields on the spontaneous bioelectrical activity of snail neurons med./bio.

By: Moghadam MK, Firoozabadi M, Janahmadi M

Published in: J Membr Biol 2011; 240 (2): 63-71

To study the effects of 50 Hz magnetic fields in the range of magnetic flux densities relevant to current environmental exposures on action potential, after-hyperpolarization potential and neuronal excitability in neurons of land snails (Helix aspersa).

All experiments were performed on single neuron units (F1; n=42) located in the visceral ganglion of the snail.

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: continuous for 18 min or 20 min (see "additional information")	magnetic flux density: 207.2 µT effective value (2.83 µT, 6.02 µT, 14.91 µT, 45.87 µT, 109.34 µT, 207.2 µT in the exposure area within the coils)

Frequency	50 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	continuous for 18 min or 20 min (see "additional information")

Exposure source	Helmholtz coils
Setup	pair of Helmholtz coils with a diameter of 20 cm, spaced 10 cm apart, consisting each of 325 turns of 0.5 mm copper wire; field homogeneity better than 0.1 µT in the exposure area inside the coils
Additional info	exposure time: 18 min exposure - 2 min examination without exposure - additional 2 min exposure (= 20 min)

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	207.2 µT	effective value	measured	-	2.83 µT, 6.02 µT, 14.91 µT, 45.87 µT, 109.34 µT, 207.2 µT in the exposure area within the coils

Exposed system:

Investigated system:

Time of investigation:

When the neurons were exposed to magnetic fields at the various magnetic flux densities, marked changes in neuronal excitability, firing rate (decrease, i.e. inhibition of neuronal activity) and after-hyperpolarization potential amplitude (increase) were found. These effects seemed to be related to the intensity, type (single and continuous or repeated and cumulative) and length of exposure (18 or 20 min). The extremely low frequency magnetic field exposures affected the excitability of F1 neuronal cells in a nonmonotonic manner, disrupting their normal characteristic and synchronized firing patterns.

Study character:

Azanza MJ et al. (2013): Synchronization dynamics induced on pairs of neurons under applied weak alternating magnetic fields
Moghadam MK et al. (2008): 50 Hz alternating extremely low frequency magnetic fields affect excitability, firing and action potential shape through interaction with ionic channels in snail neurones
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): Electrophysiologic responses of snail brain neurons under applied 50-Hz alternating magnetic fields
Kullnick U (1995): Do weak, low pulsed frequency, high-frequency electromagnetic or magnetic fields alter the basic bioelectrical parameters of nerve cells in vineyard snails (Helix pomatia L.) ? / I. Electromagnetic fields
Balaban PM et al. (1990): Influence of a stationary magnetic field on bioelectric properties of snail neurons