Study type: Medical/biological study (experimental study)

Electromagnetic field (EMF) effects on channel activity of nanopore OmpF protein. med./bio.

Published in: Eur Biophys J 2009; 38 (8): 1069-1078

Aim of study (acc. to author)

To determine the effects of low-intensity electromagnetic fields at 925 MHz on the OmpF channel-forming protein (outer membrane protein F, a transmembrane protein of E. coli).

Background/further details

Ion channel activity responses were monitored under different conditions: 1) in the presence of continuous electromagnetic field exposure, 2) recovering from electromagnetic field exposure (recorded after electromagnetic field was switched off), and 3) recovering from simultaneous application of electric field and electromagnetic field. The results were based on the analysis of about 25 h of recordings at 0-180 mV in 20 mV increments.
The thermal effect of electromagnetic fields on channel activity was studied at temperatures of 22, 24, and 26°C, taking channel activity at 20°C as control.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 925 MHz
Modulation type: CW
Exposure duration: not given in the article
Exposure 2:
  • unspecified
Modulation type: single pulse
  • U = 200 mV
Exposure 3: 925 MHz
Modulation type: single pulse, CW
Exposure duration: not given in the article

Exposure 1

Main characteristics
Frequency 925 MHz
Type
Exposure duration not given in the article
Modulation
Modulation type CW
Exposure setup
Exposure source
Setup 4.5 cm long 1.5 cm x 1.5 cm glass chamber placed in a Faraday cage perpendicular to the E-field; two 1 mm thick aluminum antennae positioned parallel at a distance of 5.5 cm with the glass chaber between them
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 244 V/m maximum calculated - -
electric field strength 4.76 V/m - calculated - sensed by the protein
power density 0.03 W/m² - calculated - at the membran location

Exposure 2

Main characteristics
Frequency
  • unspecified
Type
Modulation
Modulation type single pulse
Exposure setup
Exposure source
  • not specified
Parameters
Measurand Value Type Method Mass Remarks
cf. remarks - - - - U = 200 mV

Exposure 3

Main characteristics
Frequency 925 MHz
Type
Exposure duration not given in the article
Additional info plus short electric pulses
Modulation
Modulation type single pulse, CW
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 244 V/m maximum calculated - -
electric field strength 4.76 V/m - calculated - sensed by the protein
power density 0.03 W/m² - calculated - at the membran location
cf. remarks - - - - U = 200 mV

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • before exposure
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

The data showed an increase in the frequency of channel gating and voltage sensitivity under electromagnetic field exposure. These effects lasted for several milliseconds after the electromagnetic field source was terminated. However, the conductance levels of channels did not change significantly. The changes in the channel activity could be due to a minor rise in localized temperature induced by the electromagnetic field microscopically.
The authors conclude that electromagnetic field exposure affects both the dynamics and conformation of the ion channel.

Study character:

Study funded by

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