Anyone surveying physiological and pharmacological journals can readily see that the biological actions of calcium ion are of increasingly widespread current interest. The scope of investi gated actions and reactions in which a role for calcium ion is of some importance is so numerous as to convey the impression that calcium ion is everywhere and interacts with everything. This being so, the challenge in contemporary research is to focus on investigation of those actions of calcium ion which, in some manner, influence either significant physiological parameters or the manner in which...