Dantrolene modulates the influence of steady magnetic fields on hippocampal evoked potentials in vitro

Direct current-generated magnetic fields (2-3 mT, 20-min exposure) exerted biphasic effects on the population spike recorded from hippocampal slices. The initial decrease in the potential, observed during exposure of the slic es to magnetic fields was followed by a recovery/amplification phase, which began after terminating the magnetic field action. During that phase the p opulation spike exceeded the amplitude observed before application of the m agnetic fields. The pattern of magnetic fields influence was not affected e ither by (+)-5-methyl-10,11-dihydro-5H-dibenzo (a,d) cyclohepten-5,10-imine maleate (MK801), or by D,L,-2amino-5phosphonovalerate (APV), a noncompetit ive and competitive NMDA receptor antagonist, respectively. The rising phas e of the potential, however, was eliminated by dantrolene, an inhibitor of intracellular Ca2+ channels. This suggests that intracellular calcium chann els participate in the mechanism of the influence of the direct current mag netic fields on the function of the hippocampal tissue. (C) 2000 Wiley-Liss , Inc.