TEMPORALLY INCOHERENT MAGNETIC-FIELDS MITIGATE THE RESPONSE OF BIOLOGICAL-SYSTEMS TO TEMPORALLY COHERENT MAGNETIC-FIELDS

We have previously demonstrated that a weak, extremely-low-frequency m agnetic field must be coherent for some minimum length of time (approx imate to 10 s) in order to affect the specific activity of ornithine d ecarboxylase (ODC) in L929 mouse cells. In this study we explore wheth er or not the superposition of an incoherent (noise) magnetic field ca n block the bioeffect of a coherent 60 Hz magnetic field, since the su m of the two fields is incoherent. An experimental test of this idea w as conducted using as a biological marker the twofold enhancement of O DC activity found in L929 murine cells after exposure to a 60 Hz, 10 m u T-rms magnetic field. We superimposed an incoherent magnetic noise f ield, containing frequencies from 30 to 90 Hz, whose rms amplitude was comparable to that of the 60 Hz field. Under these conditions the ODC activity observed after exposure was equal to control levels. It is c oncluded that the superposition of incoherent magnetic fields can bloc k the enhancement of ODC activity by a coherent magnetic field if the strength of the incoherent field is equal to or greater than that of t he coherent field. When the superimposed, incoherent noise field was r educed in strength, the enhancement of ODC activity by the coherent fi eld increased. Full ODC enhancement was obtained when the rms value of the applied EM noise was less than one-tenth that of the coherent fie ld. These results are discussed in relation to the question of cellula r detection of weak EM fields in the presence of endogenous thermal no ise fields. (C) 1994 wiley-Liss, Inc.