THE QUANTITATIVE EFFECT OF FIFTEEN CHEMICALLY RELATED GLYCOSIDES AND GENINS ON THE EMBRYONIC CHICK HEART

¹ From the Department of Therapeutics, New York University College of Medicine; and the Department of Anatomy, Long Island College of Medicine

1. A procedure has been described for the comparison of the digitaloids with respect to their ability to produce atrio-ventricular block in the embryonic chick heart. This preparation has been shown to offer a number of theoretical and practical advantages over those in general use. A method for expressing the results has been suggested.

2. Fifteen chemically related cardiac glycosides and genins have been studied by the chick heart procedure and the following tentative conclusions have been reached as to the influence of various structural configurations on cardiac action: (a) all other factors being constant, variation in the substituents on the steroid nucleus is capable of causing profound changes in activity; (b) the desoxy sugars give rise to marked enhancement in the activity of the genins, the weaker the genin the greater the enhancement, and this effect seems not to depend on the nature of the particular desoxy sugar; and (c) conjugation with glucose in addition to desoxy sugar never increases the potency of the glycoside and usually decreases it significantly.

3. The results obtained with the embryonic chick heart for digitaline Nativelle, digoxin and lanatoside C have been shown to correlate at least in order of magnitude, with the oral therapeutic dosage. On the other hand, the values for these three drugs by the cat and frog methods bear no apparent relationship to the clinical dose. The possible reasons for this have been discussed.

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