Calcium Ions

The involvement of calcium (Ca) in living organisms has long been recognized, particularly its presence in invertebrate shells and vertebrate bones. It was not, however, before the studies of S. Ringer (1882), who showed that its presence was necessary for normal heart beating, that its role in physiological processes was assessed. Since that time, it has become more and more apparent that the number of cellular functions that are triggered, regulated, or otherwise influenced by calcium ions is quite large, ranging from activation of a whole palette of enzymes to playing a pivotal role as an intracellular messenger in the physiology of excitable cells (Carafoli and Crompton, 1978; Campbell, 1983).