SERIAL DETERMINATIONS OF CARDIAC OUTPUT (BALLISTOCAR- DIOGRAM) AND ELECTROCARDIOGRAM IN NORMAL MAN AFTER THE INTRAVENOUS ADMINISTRATION OF PURIFIED CARDIAC GLYCOSIDES’

The mode of action of digitalis in both the failing and the normal circulations of man remains controversial (1-4) and the circulatory effects of the purified digitalis glycosides have but recently been investigated (5-8). Many of the previous observations have been made on animals, or the excised organs of ani-mals. Often these data have not been applicable to man (6, 9, 10). Additional observations of a physiologic nature in man seemed desirable. This investigation had two purposes. First, to determine the effects produced by several purified cardiac glycosides on four components of the normal circula-tion, namely cardiac output, electrocardiogram, cardiac rate, and arterial blood pressure. Second, to compare the three glycosides, lanatoside C, digoxin, and digitoxin with regard to their effects on these circulatory components. These three drugs are of known chemical structure, available in purified crystalline form and, therefore, superior to preparations of digitalis, the composition of which is not only unknown but variable (8). In the present study we were interested particularly in the primary effects o