The relative toxicity of the chlorides of magnesium,calcium,potassium and sodium

Sodium, potassium, calcium and magnesium are normal constituents of the animal body. However, when introduced intravenously in larger quantities they may have a poisonous effect. Pharmacologists frequently speak of the effect as a salt action. This means, at least according to the definition of some pharmacological writers, that the effect is due to osmotic changes. If this were true, the toxicity of all four inorganic, basic elements ought to be the same if introduced in the same molecular concentration. Although, as far as we know, a direct comparative study of the toxicity of these inorganic substances has never yet been made, a glance at the various data in the literature suffices to show that these substances differ greatly in their toxicity. As far as we can gather, it is generally assumed that potassium is the most poisonous; calcium seems to be considered a good deal less poisonous than potassium, but definitely more so than magnesium. As to sodium, only recently Loeb and his pupils called attention to its poisonous effect.

In a series of experiments on dogs, we compared the toxicity of these four inorganic elements in intravenous injections of their chlorides. In every instance molecular solutions were employed. The toxicity of each of these salts was tested on twelve animals. The injections were made by four different methods, using three dogs for each method, namely, by injections through the jugular vein, through the femoral vein, through the splenic vein, and intra-arterially, through the central end of the carotid artery. In the latter case the solution was driven by high pressure through a capillary tube. Except in the case of sodium chloride, the solutions ran in uniformly one C.C. per minute.