Medical/biological study (experimental study)

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 med./bio.

By: Marchionni I, Paffi A, Pellegrino M, Liberti M, Apollonio F, Abeti R, Fontana F, D'Inzeo G, Mazzanti M

Published in: Biochim Biophys Acta Biomembr 2006; 1758 (5): 597-605

Aim of study (acc. to author)

The aim of the study was a qualitative comparison, using the same preparation, patch-clamp unit, and experimental protocols, between the effects of two different electromagnetic field stimulations on the electrophysiological properties of isolated adult rat dorsal root ganglions.

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: continuous for 30 min	magnetic flux density: 125 µT effective value (0.48 mV/m induced EF)
Exposure 2: 900 MHz Modulation type: CW Exposure duration: continuous for 30 min	SAR: 1 W/kg unspecified

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	continuous for 30 min
Additional info	Reference article: R. Tonini, M.D. Baroni, E. Masala, M. Micheletti, A. Ferroni, M. Mazzanti, Calcium protects differentiating neuroblastoma cells during 50 Hz electromagnetic radiation, Biophys. J. 81 (2001) 2580-2589.

Exposure setup

Exposure source	Helmholtz coils
Setup	The experimental chamber was encircled with the coils. For control experiments the current flowing in the coil was zeroed by switching off the waves generator. During the entire exposure, the cells were observed on the inverted microscope.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	125 µT	effective value	measured	-	0.48 mV/m induced EF

Exposure 2

Main characteristics

Frequency	900 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 30 min
Additional info	Reference articles: 1) K.C. Garg Gupta, R. Bahl, P. Barthia, Microstrip Lines and Slotlines, 2nd ed. Artech House, Boston and London, 1996. 2) M. Liberti, F. Apollonio, A. Paffi, M. Pellegrino, G. D'Inzeo, A coplanar waveguide system for cell exposure during electrophysiological recordings, IEEE Microwave Theory and Techniques Symposium, Fort Worth, 2004.

Modulation

Modulation type	CW

Exposure setup

Exposure source	waveguide
Chamber	The exposure system based on coplanar waveguide consisting of an open propagating structure with a dielectric substrate on which three metallic strips are deposited. A glass was chosen as a dielectric substrate to replace the microscope head stage.
Additional info	The direction of E-field was almost parallel to the Petri dish surface and perpendicular to the glass surface.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	1 W/kg	unspecified	calculated	-	-

Exposed system:

intact cell/cell culture

Methods Endpoint/measurement parameters/methodology

cell function: single channel ionic currents (calcium channel and (calcium-activated) potassium channel currents); cell firing rate/action potentials (current-clamp technique and single channel recording technique)

Investigated system:

intact cell/cell culture

Time of investigation:

before exposure
during exposure

Main outcome of study (acc. to author)

The data demonstrate that the firing rate of these sensory neurons can be modified by 50/60 Hz magnetic field but not by low level 900 MHz fields.
The action of the 50/60 Hz magnetic field was biphasic. At first, the number of action potentials increased in time. Following this early phase, the firing rate decreased more rapidly than in control conditions. The explanation can be found at the single-channel level: exposed dorsal root ganglion neurons acutely showed increased functionality of calcium channels. In parallel, a calcium-activated potassium channel was able to increase its mean open time.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Fondazione Silvio Tonchetti-Provera, Milano, Italy
Ministero dell' Università e della Ricerca (MIUR (formerly MURST (Ministero dell' Università e della Ricerca Scientifica e Tecnologica); Ministry of University and Research), Italy
University "La Sapienza", Rome, Italy

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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 med./bio.

Aim of study (acc. to author)

Background/further details

Endpoint

Exposure

Exposure 1

Main characteristics

Exposure setup

Parameters

Exposure 2

Main characteristics

Modulation

Exposure setup

Parameters

Methods Endpoint/measurement parameters/methodology

Main outcome of study (acc. to author)

Study funded by

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