Potassium Content of Human Cardiac Muscle.

Abstract

The investigations of Ringer, 1 Howell, 2 and Zwaardemaker 3 and their coworkers offer the strongest evidence that the element potassium is an indispensable factor in cardiac activity. This conclusion is derived from experimental work on hearts of the lower animals, as a rule amphibians. Zwaardemaker alone has endeavored to adapt his findings to human heart function, in that he has theoretically estimated the kinetic energy developed by the emanation of the Beta particles of potassium.

Inasmuch as there are few reliable and accurate series of determinations of potassium in cardiac muscle to be found in the literature, Zwaardemaker's estimation must of necessity be approximate. It therefore seemed desirable that a relatively large number of potassium determinations be made using a method the results of which would be as nearly representative as it was possible to obtain them. The one of choice, an adaptation of the old platinum reduction procedure of Neubauer 4 appeared to be the best. A detailed description of the method with the few modifications will appear in the complete article.

Two series of determinations of potassium have been undertaken, the first comprising 25 hearts, which, because of later modifications in the analysis is not to be looked upon as being as representative as the second series of 30 determinations, of which 27 have so far been completed. However, there is considerable variation in the potassium content of the human heart and for the specimens obtained at that time the means of the first series at least may be regarded as approximations.

Zwaardemaker's estimate of the kinetic energy developed by the potassium in a human heart of 300 gm. is 4.10·10^-4 erg seconds. The above mean K.E. output for a heart of similar mass is only 2.85·10^-4 erg seconds.