WEAK EXTREMELY-LOW-FREQUENCY MAGNETIC-FIELDS AND REGENERATION IN THE PLANARIAN DUGESIA-TIGRINA

Extremely-low-frequency (ELF), low-intensity magnetic fields have been shown to influence cell signaling processes in a variety of systems, both in vivo and in vitro. Similar effects have been demonstrated for nervous system development and neurite outgrowth. We report that regen eration in planaria, which incorporates many of these processes, is al so affected by ELF magnetic fields. The rate of cephalic under continu ous exposure to combined DC (78.4 mu T) and AC (60.0 Hz at 10.0 mu T-p eak) magnetic fields applied in parallel was found to be significantly delayed (P much less than 0.001) by 48 +/- 1 h relative to two differ ent types of control populations (MRT similar to 140 +/- 12 h). One co ntrol population was exposed to only the AC component of this field co mbination, while the other experienced only the ambient geomagnetic fi eld. All measurements were conducted in a low-gradient, low-noise magn etics laboratory under well-maintained temperature conditions. This de lay in regeneration was shown to be dependent on the planaria having a fixed orientation with respect to the magnetic field vectors. Results also indicate that this orientation-dependent transduction process do es not result from Faraday induction but is consistent with a Ca2+ cyc lotron resonance mechanism. Data interpretation also permits the tenta tive conclusion that the effect results from an inhibition of events a t an early stage in the regeneration process before the onset of proli feration and differentiation. (C) 1995 Wiley-Liss. Inc.