Calcium Dynamics

Calcium is critically important for a vast array of cellular functions, as can be seen by a quick look through any physiology book. For example, in this book we discuss the role that Ca²⁺ plays in muscle mechanics, cardiac electrophysiology, bursting oscillations and secretion, hair cells, and adaptationin photoreceptors, among other things. Clearly, the mechanisms by which a cell controls its Ca²⁺ concentration are of central interest in cell physiology.

There are a number of Ca²⁺ control mechanisms operating on different levels, all designed to ensure that Ca²⁺ is present in sufficient quantity to perform its neces sary functions, but not in too great a quantity in the wrong places. Prolonged high cytoplasmic concentrations of Ca²⁺ are toxic. For example, cellular Ca²⁺ overload can trigger apoptotic cell death, a process in which the cell kills itself. In muscle cells, high intracellular Ca²⁺ is responsible for prolonged muscle tension and rigor mortis.