The Effect of Lithium on the Electrocardiogram of Animals and Relation of This Effect to the Ratio of the Intracellular and Extracellular Concentrations of Potassium

The cardiac toxicity of the potassium ion is fa- miliar from observations both in animals and in man. With elevation of the serum potassium a vir- tually pathognomonic sequence of electrocardio- graphic changes occurs. Of interest is the effect on the heart of elements from the same periodic group, e.g., lithium, rubidium, and cesium. With the reporting (1-5) of patients with severe un- toward reactions from lithium salts taken as a so- dium salt substitute, it became of practical signifi- cance to evaluate the role of the cardiac toxicity (if any) in the total picture of lithium intoxication. Unexpectedly these studies of the effects of lithium disclosed interesting features of potassium me- tabolism. Because of ramifications of possible theoretical significance in this connection, a miiore detailed report than that of four years ago (6) was deemed desirable.