Basic Concepts of Ca²⁺ Signaling in Cells and Tissues

Abstract

Living tissues are complex organizations of individual cells and to perform their specific functions the activity of each cell within the tissue must be regulated in a coordinated manner. The mechanisms through which this regulation occurs can be equally complex, but a common way to exert control is via neural transmission or hormonal stimulation. Irrespective of the organization of the extracellular control system, the regulatory signals need to be translated into an intracellular messenger that can modulate the cellular processes. Again, there are a variety of intracellular messengers that achieve this aim, including cAMP, cGMP and NO, but here we focus on the calcium ion as the internal messenger. The objective of this article is to provide an overview of the basic mechanisms of how Ca²⁺ serves as a signaling messenger. For greater detail, the reader must refer to the many extensive reviews (for example, Berridge et al., 2003; Berridge et al., 2002). The details of the individual mechanisms are extremely important since they can confer specificity on the signaling model. As a result, model simulations of Ca²⁺ signaling are most useful when the model is designed for a specific cell type and sufficient experimental detail can be incorporated.