Acute exposure to a moderate strength static magnetic field reduces edema formation in rats.
External application of static magnetic fields (SMF), used specifically for the treatment of inflammatory conditions such as soft tissue injuries, has recently become popular as a complementary and/or alternative therapy with minimal investigation into efficacy or mechanism. Localized inflammation was induced via injection of inflammatory agents lambda-carrageenan (CA) or histamine into rat hindpaws, alone or in conjunction with pharmacological agents, resulting in a spatially and temporally defined inflammatory reaction. Application of a 10- or 70-mT, but not a 400-mT, SMF for 15 or 30 min immediately following histamine-induced edema resulted in a significant, 20-50% reduction in edema formation. In addition, a 2-h, 70-mT field application to CA-induced edema also resulted in significant (33-37%) edema reduction. Field application before injection or at the time of maximal edema did not influence edema formation or resolution, respectively. Together, these results suggest the existence of a therapeutic threshold of SMF strength (below 400 mT) and a temporal dependence of efficacy. Administration of pharmacological agents directed at nitric oxide signaling and L-type Ca(2+) channel dynamics in conjunction with SMF treatment and histamine-induced edema revealed that the potential mechanism of SMF action may be via modulation of vascular tone through effects on L-type Ca(2+) channels in vascular smooth muscle cells.
Morris
Cassandra E
CE
Department of Biomedical Engineering, University of Virginia Health Sciences Center, Health System, Charlottesville, VA 22908, USA.
Skalak
Thomas C
TC
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002120:Calcium Channel Agonists / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000187:drug effects / Q000378:metabolism; D002351:Carrageenan; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D004487:Edema / Q000139:chemically induced / Q000378:metabolism / Q000517:prevention & control*; D004574:Electromagnetic Fields; D006632:Histamine; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism / Q000517:prevention & control*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism / Q000528:radiation effects*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012720:Severity of Illness Index; D015398:Signal Transduction / Q000528:radiation effects; D013997:Time Factors
D002120:Calcium Channel Agonists; D020746:Calcium Channels, L-Type; D009569:Nitric Oxide; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D006632:Histamine; D002351:Carrageenan; D001120:Arginine; D019001:Nitric Oxide Synthase; D002118:Calcium