Electrical fields, nerve growth and nerve regeneration.

The presence of voltage gradients within developing and damaged tissues led to the notion that the resultant electrical fields provide instructional cues to cells. Field effects on avian and amphibian neurones in vitro include increased differentiation, turning of neurites towards the cathode, increased rate of growth towards the cathode, resorption of anodefacing neurites, increased branching and increased filopodial activity. Electric fields enhance regeneration of damaged PNS and CNS neurones in animals as diverse as lampreys, frogs, rats and guinea-pigs, but the mechanisms by which fields produce their effects are not understood. Further examination of the interaction of fields with intracellular elements, such as the cytoskeleton and second messenger systems, may offer some insight.