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September 18, 1915


JAMA. 1915;LXV(12):1033-1034. doi:10.1001/jama.1915.02580120045020

It has long been known that potassium salts (or, speaking more correctly, potassium ions) have a depressant action on the heart; the demonstration of this has become a commonplace experiment in the pharmacologic laboratory. This poisonous action was first investigated in connection with the frog heart, but has been repeatedly confirmed for the mammalian heart. Just how toxic a potassium salt is for the mammalian heart can be shown only by experiments on the isolated organ; for when such salt is administered by mouth or even intravenously at a slow rate, it is, under ordinary circumstances, removed so rapidly from the circulating blood that unless enormous doses are given, the concentration which would be fatal or markedly toxic to the heart is not reached. With the isolated mammalian heart, however, it has been shown5 that when the circulating fluid contains 0.085 per cent, of potassium chlorid, the heart rate