relatively well understood simple systems to the complex living systems. where all effects occur simultaneously. The backgrounds of the invited contributors include biochemistry. biophysics. cell biology. electrical engineering. electrochemistry. electrophysiology. medicine and physical chemistry. As a result of this diversity. the mechanistic models reflect the differing approaches used by these disciplines to explain the same phenomena. Areas of agreement define the common ground. while the areas of divergence provide opportunities for refining our ideas through further experimentation. To facilitate the interaction between the different points of view, the authors have clearly indicated those published observations that they are trying to explain. i.e. the experiments that have been critical in their thinking. This should establish a concensus regarding important observations. In the discussion of theories.