title: Acute exposure to a moderate strength static magnetic field reduces edema formation in rats.
abstract: 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.
authors.affiliation: Department of Biomedical Engineering, University of Virginia Health Sciences Center, Health System, Charlottesville, VA 22908, USA.
authors.forename: Cassandra E
authors.initials: CE
authors.lastname: Morris
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Skalak
mesh_terms: 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
chemical_list: 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