STUDIES ON VERATRUM ALKALOIDS. XXXVIII. THE EFFECTS OF l-ETHOMOXANE AND OF VERATRAMINE ON ISOLATED MAMMALIAN AND INVERTEBRATE HEARTS AND ON THE ISOLATED GUINEA-PIG ILEUM

¹ Department of Pharmacology, Harvard Medical School, Boston, Massachusetts

l-Ethomoxane (l-S-ethoxy-2-butylaminomethyl-l ,4-benzodioxane hydrochloride) has a veratramine-like negative chronotropic action on dog heart-hung and isolated guinea-pig atrium preparations. The synthetic drug has only one-thirtieth of the potency of veratramine on the dog heart and between one-tenth in and one-twentieth of time potency of veratramine on the guineapig atrium. l-Ethmoxane resembles other polycyclic amines which exhibit veratrarnine-like properties on the heart in that, in contrast to veratramine itself, it has a negative inotropic action as well as a negative chronotropic action. Large doses of l-ethomoxane give rise to an irregular sinus arrhythmia resembling that sometimes seen with veratramine. Both drugs caused slowing in time neurogenic isolated lobster heart, and, in doses too small to affect the resting rate, antagonized the positive chronotropic action of epinephrine. l-Ethomoxane, in common with veratramine, has a nonspecific smooth muscle depressant action, antagonizing responses of isolated guinea-pig ileum to acetylcimobine, barium and histamine.