Studies on the Effect of Static Magnetic Fields on Biological Systems

Considerable evidence now exists relating exposure to static magnetic flelds (SMFs) to changes in a number of biological systems, particularly those whose function is linked to the properties of membrane ion channels. Most of the reported efiects of moderate SMF may be explained on the basis of alterations in membrane calcium ion ∞ux as well as intracellular cal- cium availability. The mechanism suggested to explain these efiects is based on the diamagnetic anisotropic properties of membrane phospholipids. It is proposed that reorientation of these molecules during SMF exposure will result in the deformation of imbedded ion channels, thereby altering their activation kinetics. Channel inactivation kinetics would not be expected to be in∞uenced by these flelds because the mechanism for inactivation is not located within the in- tramembraneous portion of the channel. Patch-clamp studies of calcium channels have provided support for this hypothesis, as well as demonstrating a temperature dependency that is under- standable on the basis of the membrane thermotropic phase transition. 1. INTRODUCTION The in∞uence of static magnetic flelds (SMFs) on biological systems has been an area of considerable interest for many years. These flelds, unlike time-varying (electromagnetic) flelds, are not associated with induced electric currents except during activation and deactivation or when there is movement within the fleld. Our interest has been primarily on moderate intensity flelds, those with strengths of 1mT to 1T. Many of the initial reports on the bioefiects of these flelds were phenomenological descriptions without attempts to identify a mechanism of action (1{5). The present report describes the development of a hypothesis su-cient to explain the action of moderate SMFs on biological systems. This proposed mechanism involves the efiect of SMFs on the molecular structure of excitable membranes, an efiect su-cient to modify the function of imbedded ion-speciflc channels. This hypothesis would explain virtually all of the bioefiects attributed to these flelds and is testable using several difierent neurophysiological techniques. 2.