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).
Exposure duration: 30 to 40 min
Exposure duration: 8 min for each frequency
|Exposure duration||30 to 40 min|
|magnetic flux density||0.0034 nT||-||-||-||-|
|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|
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.