Cellular calcium metabolism: Activation and antagonism

The role of Ca²⁺ as a mediator of many cellular responses, including stimulus-secretion and excitation-contraction coupling, is reviewed. Pathways of Ca²⁺ mobilization are discussed in terms of both intracellular and plasmalemmal processes. The extent to which specific antagonists exist, active at these several sites, is noted, with particular emphasis on the clinically available Ca²⁺ channel antagonists, including verapamil, nifedipine, and diltiazem.