Calcium Wave Propagation Triggered by Local Mechanical Stimulation as a Method for Studying Gap Junctions and Hemichannels

Intercellular communication is essential for the coordination and synchronization of cellular processes. Gap junction channels play an important role to communicate between cells and organs, including the brain, lung, liver, lens, retina, and heart. Gap junctions enable a direct route for ions like calcium and potassium, and low molecular weight compounds, such as inositol 1,4,5-trisphosphate, cyclic adenosine monophosphate, and various kinds of metabolites to pass between cells. Intercellular calcium wave propagation evoked by a local mechanical stimulus is one of the gap junction assays to study intercellular communication. In experimental settings, an intercellular calcium wave can be elicited by applying a mechanical stimulus to a single cell. Here, we describe the use of monolayers of primary bovine corneal endothelial cells as a model to study intercellular communication. Calcium wave propagation was assayed by imaging fluorescent calcium in bovine corneal endothelial cells loaded with a fluorescent calcium dye using a confocal microscope. Spatial changes in intercellular calcium concentration following mechanical stimulation were measured in the mechanical stimulated cell and in the neighboring cells. The active area (i.e., total surface area of responsive cells) of a calcium wave can be measured and used for studying the function and regulation of gap junction channels as well as hemichannels in a variety of cell systems.