EXTERNAL SIGNALS AND INTERNAL OSCILLATION DYNAMICS - BIOPHYSICAL ASPECTS AND MODELING APPROACHES FOR INTERACTIONS OF WEAK ELECTROMAGNETIC-FIELDS AT THE CELLULAR-LEVEL

The question of whether or not non-thermal (sub-kT) electromagnetic fi elds in the non-ionizing frequency range (from extremely low frequency (ELF) to microwave) can influence the function of biological systems is currently of extreme interest and the subject of both ongoing exper iments and controversial discussions. In this review, a brief presenta tion of some of the most prominent experimental results is given, and the principal problems are discussed from both physical and biological points of view. The necessary requirements for modelling approaches a re described, including the entire sequence from the primary physical interaction via the secondary biological mechanisms (transductive step s) to the final response. Very smalt changes in the underlying non-lin ear kinetics caused by very weak coherent signals and noise can lead t o strong, but reversible, alterations in the internal non-linear proce sses and associated biological function. The results of many detailed investigations are given. These include ELF field influences on G-prot ein activation dynamics, magnetic field influences on radical pair rec ombination reactions and weak signal amplification by stochastic reson ance, All processes are incorporated within Ca2+ signal pathway models . The concept and models presented describe frequency-dependent and fr equency-coded influences of very weak fields. The relevance of the res ults can be shown by sophisticated biological experiments.