ACTION OF 50 HZ MAGNETIC-FIELDS ON CYCLIC-AMP AND INTERCELLULAR COMMUNICATION IN MONOLAYERS AND SPHEROIDS OF MAMMALIAN-CELLS

To investigate the influence of physiological parameters such as cell density and three-dimensional cell contact on the biological action of a 2 mT/50 Hz magnetic field, mouse fibroblasts were exposed as monola yers and as multicellular spheroids. Changes in cyclic AMP content of cells and alterations in gap junction-mediated intercellular communica tion were measured immediately after 5 min of exposure to the field. I n monolayers of intermediate cell density (1 x 10(5) cells/cm(2)), the field treatment caused an increase in cAMP to 121% of the control lev el, whereas, at 3 x 10(5) cells/cm(2) (near confluence), a decrease to 88% of the unexposed cells was observed. Furthermore, field exposure stimulated gap-junction communication to 160% of the control level as determined by Lucifer yellow dye exchange. In spheroids, alterations i n the radial profile of cellular cAMP were observed that were due both to field-induced local cAMP changes and to increased gap-junction per meability for this second messenger, the latter causing radial cAMP gr adients to be flattened. The results indicate a strong dependence of f ield action on physiological parameters of the system exposed. (C) 199 5 Wiley-Liss.