Spinning disk confocal laser microscopy systems can be used for observing fast events occurring in a small volume when they include a sensitive electron-multiplying CCD camera. Such a confocal system was recently used to capture the first pictures of intracellular calcium signalling within the projections of endothelial cells to the adjacent smooth muscle cells in the blood vessel wall. Detection of these calcium signals required high spatial and temporal resolution. A newly developed calcium ion (Ca(2+)) biosensor was also used. This exclusively expressed in the endothelium and fluoresced when Ca(2+) concentrations increased during signalling. This work gives insights into blood vessel disease because Ca(2+) signalling is critical for blood flow and pressure regulation.