Cellular Calcium: Nervous System

Calcium ions play numerous important roles in the function of nerve cells. Calcium’s involvement in neurotransmitter release is one of its key roles, and was one of the first to be recognized. Early observations demonstrated that extracellular calcium was required for neurotransmitter release (Harvey and Macintosh 1940). Subsequent studies established that transmitter release was evoked by calcium entry and a rise in [Ca2+]i, the intracellular free calcium concentration. This sequence of events accounted for the dependence of the reaction on external calcium (Katz 1969; Llinas et al. 1976; Drapeau and Blaustein 1983a). As we shall see, the modulation of synaptic transmission, and related fundamental aspects of transmitter release associated with memory and learning, are all profoundly influenced by calcium.