Electromagnetic fields as first messenger in biological signaling: Application to calmodulin-dependent signaling in tissue repair

Background: The transduction mechanism for non-thermal electromagnetic field (EMF) bioeffects has not been fully elucidated. This study proposes that an EMF can act as a first messenger in the calmodulin-dependent signaling pathways that orchestrate the release of cytokines and growth factors in normal cellular responses to physical and/or chemical insults. Methods: Given knowledge of Ca2+ binding kinetics to calmodulin (CAM), an EMF signal having pulse duration or carrier period shorter than bound Ca2+ lifetime may be configured to accelerate binding, and be detectable above thermal noise. New EMF signals were configured to modulate calmodulin-dependent signaling and assessed for efficacy in cellular studies. Results: Configured EMF signals modulated CaM-dependent enzyme kinetics, produced several-fold increases in key second messengers to include nitric oxide and cyclic guanosine monophosphate in chondrocyte and endothelial cultures and cyclic adenosine monophosphate in neuronal cultures. Calmodulin antagonists and downstream blockers annihilated these effects, providing strong support for the proposed mechanism. Conclusions: Knowledge of the kinetics of Ca2+ binding to CaM, or for any ion binding specific to any signaling cascade, allows the use of an electrochemical model by which the ability of any EMF signal to modulate CaM-dependent signaling can be assessed a priori or a posteriori. Results are consistent with the proposed mechanism, and strongly support the Ca/CaM/NO pathway as a primary EMF transduction pathway. General significance: The predictions of the proposed model open a host of significant possibilities for configuration of non-thermal EMF signals for clinical and wellness applications that can reach far beyond fracture repair and wound healing. (C) 2011 Elsevier B.V. All rights reserved.