Spatial heterogeneity not homogeneity of the magnetic field during exposures to complex frequency-modulated patterns facilitates analgesia.
24 young (4 mo.) and 24 old (8 mo.) male Wistar rats were exposed for 30 min. on two consecutive days to either a sham-field or to a frequency-modulated magnetic field applied through a pair of solenoids (spatially heterogeneous strength) or a Helmholtz coil (spatially homogeneous strength). The maximum field strength was about 2 microTesla. The rats exposed to the spatially heterogeneous magnetic field but not the homogeneous magnetic field exhibited strong analgesia to thermal stimuli applied to the footpads immediately after the treatment and 30 min. later. The effect accommodated 38% of the variance in the latency to respond to the thermal stimuli. These results suggest that the practice by many researchers in bioelectromagnetism to design coils to generate maximum spatial homogeneity of intensities within the exposure volume when applying complex weak magnetic fields may actually diminish any biological effects.
Martin
L J
LJ
Laurentian University, Sudbury, ON Canada.
Persinger
M A
MA
D000698:Analgesia / Q000295:instrumentation*; D000818:Animals; D008280:Magnetics / Q000295:instrumentation*; D008297:Male; D059408:Pain Management; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors