THE EFFECT OF EPINEPHRINE ON EXCISED STRIPS OF FROGS' DIGESTIVE TRACTS

¹ From the Department of Pharmacology, Washington University School of Medicine, St. Louis

1. No difference was observed in the activity of the digestive systems of recently caught and starved frogs.

2. The longitudinal muscle of the esophagus is more sensitive to adrenalin or epinephrine than is the circular muscle. Weak solutions of adrenalin produce tonic contraction of both coats and strong solutions relaxation.

3. The weak solutions of adrenalin increase the tonus and in some cases the rate and force of contractions of both muscular coats of the frog's stomach, small intestine, rectum and cloaca. Stronger solutions produce relaxation in all these organs.

4. The action of adrenalin is the same upon what appears to be the cardiac and pyloric sphincters as it is upon the adjoining organs.

5. In some cases the action of adrenalin is the same upon the ileo-colic sphincter as upon the adjoining organs; in most cases, however, the sphincter responded to all concentrations by tonic contraction.

6. Strips taken from various parts of the frog's small intestine react to the same concentration of adrenalin in practically the same manner.

7. The lower part of the alimentary canal of the frog, the intestine, rectum and cloaca, appear to be more sensitive to adrenain than the circular esophagus. They responded by contraction and relaxation to much weaker solutions than did the circular esophagus.

8. Adrenalin brought about spontaneous rhythmical contractions in some strips which had not been present and in others it caused the contractions to be increased in force and rate for long periods.

9. After the strips were bathed with adrenalin the tonus waves appeared to be more frequent than without the adrenalin.

10. The thoracic-lumbar autonomic nervous system must supply all the organs and sphincters except possibly the ileocolic with both tonic augmentative and inhibitory nerve fibers. Weak solutions of adrenalin excite the tonic augmentative fibers, strong solutions of adrenalin excite the inhibitory fibers.

11. Changes in hydrogen-ion concentration of the Ringer's bath due to the addition of adrenalin chloride do not alter the reactions of the tissues.

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