Neurotransmitters and a wide variety of hormones act on specific membrane receptors, giving rise to a signal transduction cascade where a complex interplay between second messengers and signalling proteins eventually leads to appropriate physiological responses. It also follows, that any derangement in the control of all these signals may be the cause of cell malfunctioning and, potentially, basis for the insurgency of pathological conditions. On the other hand, many therapies rely on a pharmacological intervention at this level. Since its establishment at Dibit in 1992, the research activity of the Unit of Cellular Neurophysiology has been mainly directed towards the investigation of the mechanisms that control cell signalling and neurotransmitter release. Particular interest has been paid to the study of Ca2+ distribution among the various subcellular compartments