Intramembrane Proteins Clustering Induced by 50 Hz Pulsed Magnetic Fields is Reverted to a Random Distribution in the Absence of the Field Exposure

Biological effects of extremely low frequency (ELF) electromagnetic fields (EMF) seem to be mediated by the plasma membrane. Many hypotheses have been suggested to explain the mechanisms by which ELFEMF affect cell functions. In particular it has been proposed that EMF may affect the cell receptor function, or ion channel formation or receptor capping. (Adey and Lawrence 1984; Chiabrera et al. 1991) In some conditions electroosmotic and electrophoretic effects have been reported to affect the intramembrane protein (IMP) distribution (Poo and Robinson 1977, Mc Laughlin and Poo 1981; Giugni et al. 1987). The IMP are normally randomly distributed at the cell membrane and clusterization is an event related to specific and aspecific stimulations of the cell (Brown and Loew 1994). In a previous work (Bersani et al. 1997) we found that a significant clusterization of IMP takes place after 1–2 hours of exposure to 50 Hz pulsed magnetic fields (PMF). The aim of this work was to verify whether such effect was reversible or not. For this purpose NIH 3T3 fibroblasts exposed to PMF for a time capable to induce maximal IMP clusterization were maintained for a further period of time not exposed to the field in order to determine whether IMP distribution can be reverted to control conditions.