Study type: Medical/biological study (experimental study)

Effects on Rats of Low Intensity and Frequency Electromagnetic Field Stimulation on Thoracic Spinal Neurons Receiving Noxious Cardiac and Esophageal Inputs. med./bio.

Published in: Neuromodulation 2005; 8 (2): 79-87

Aim of study (acc. to author)

To study the effects of electromagnetic fields on the activity of thoracic spinal neurons responding to noxious visceral stimuli (low intensity and low frequency electromagnetic field stimulation provides substantial pain relief in patients with various chronic pains).

Background/further details

A mixture of algogenic chemicals for noxious cardiac stimulation was administered by catheter. Noxious esophageal distension was produced by water inflation of a latex balloon.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 952 mHz
Exposure duration: 30 to 40 min
Exposure 2: 839–952 mHz
Exposure duration: 8 min for each frequency

Exposure 1

Main characteristics
Frequency 952 mHz
Type
Exposure duration 30 to 40 min
Exposure setup
Exposure source
Setup a pair of Helmholtz coils (3 x 3 inches in diameter) placed in parallel on each side of the rat's chest .
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.0034 nT - - - -

Exposure 2

Main characteristics
Frequency 839–952 mHz
Type
Exposure duration 8 min for each frequency
Additional info Exposures were performed at 5 different frequencies (0.952 Hz, 0.924 Hz, 0.896 Hz, 0.868 Hz and 0.839 Hz)
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.0031 nT - unspecified - at 0.868 Hz
magnetic flux density 0.0034 nT - unspecified - at 0.952 Hz
magnetic flux density 0.003 nT - unspecified - at 0.839 Hz
magnetic flux density 0.0033 nT - unspecified - at 0.924 Hz
magnetic flux density 0.0032 nT - unspecified - at 0.896 Hz

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

After the onset of electromagnetic fields, excitatory neuronal responses to intrapericardial chemicals were reduced in 75% (24/32) spinal neurons, increased in three neurons and were not affected in five neurons. The inhibitory effect on neurons occurred 10-20 min after the onset of the field. Even after termination of electromagnetic field exposure, the suppression of spinal neuronal activity lasted for 1-2 hours.
In contrast, excitatory responses of 39% (7/18) neurons to esophageal distension were inhibited, five were excited and six were not affected by the field.
Data showed that electromagnetic fields generally reduced nociceptive responses of spinal neurons to noxious cardiac chemical stimuli, whereas it was not effective for nociceptive responses to esophageal mechanical stimulation.

Study character:

Study funded by