[A comparative study of the action of digoxigenin-mono, bis- and tridigitoxosides in the cat heart-lung preparation (author's transl)].

In experiments using spontaneously beating and electrically driven cat hearts (heart-lung preparations), the inotropic effects and therapeutic ranges of digoxin and its bis- and monodigitoxosides were compared. The myocardial contractility was measured by the maximal rate of left ventricular pressure rise, with regard to heart rate, enddiastolic left ventricular pressure, and diastolic aortic pressure. The therapeutic range was defined as the ratio of the arrhythmogenic concentration to the threshold concentration. On molar basis, an increasing cardioactivity in the order digoxin, digoxigenin-bisdigitoxoside, digoxigenin-monodigitoxoside was found. The monoditoxoside displayed the largest therapeutic range. The therapeutic range of bis-digitoxoside was similar to that of digoxin. The findings suggest that cardiac glycosides, their cardioactive derivatives and their cardioactive metabolites, respectively, do not possess identical therapeutic ranges.