Historical and Biological Aspects of Calcium Action

Our knowledge of the biological importance of calcium began about a century ago with the serendipitous discovery made by Sydney Ringer that a solution of sodium chloride plus tap water was more efficacious in maintaining cardiac contractility than a corresponding one constituted from distilled water [23]. Ringer concluded that the minute amount of calcium present in tap water antagonized the “injurious” effects of sodium. Locke and other investigators subsequently demonstrated that motor nerves exposed to pure sodium chloride lose their stimulant effects on muscle contractility which could be restored by adding calcium (and potassium) in the proper proportions [25]. So, by the early 20th century researchers had become well aware that normal biological activity depended on specific concentrations of calcium, sodium, and potassium, with calcium occupying a key position in the natural order of things.