Effects of strong static magnetic fields on nerve excitation

Recent advances in superconducting magnet for medical equipments and for magnetic levitation gave rise to the importance of understanding biological effects of strong static magnetic fields. While the effects of pulsed or time-varying magnetic fields on the nervous system are relatively clear, the effects of static magnetic fields on the nervous system largely remain to be understood. In the present study, we investigated the effects of strong static magnetic fields of up to 8 T on action potentials of the rat sciatic nerve. Male Wistar rats were anesthetized with ether and urethane. A skin incision was made on the left hindlimb, and the muscle was separated to expose the sciatic nerve. A pair of platinum needle electrodes was inserted beneath the skin of the heel for applying electrical stimulations. The action potentials were recorded under static magnetic fields of 0 T, 2 T, 4 T, 6 T, and 8 T. The signal-to-noise ratio was improved by averaging 10 repetitive recordings. Results indicated that the exposure to strong static magnetic fields enhanced excitation of the rat sciatic nerve. Expected mechanisms for the enhancement of nerve excitation were structural changes in ion channels due to magnetic force, and Lorentz force acting on migrating ions.