The action of adrenalin on the pyloric sphincter.

Abstract

Because of the lack of consistent data bearing on the action of adrenalin on the pyloric sphincter, a further investigation of the problem has been undertaken. The results so far obtained have been sufficiently constant that a preliminary report, indicating their general character, seems justified. The investigation has been confined to a study of the immediate effects of the drug administered intravenously to anesthetized dogs. Several methods have been employed to observe the reactions of the sphincter muscle without significant differences in the results.

In dogs that have been anesthetized with morphin and ether, and allowed an hour or more for recovery from operative procedures, adrenalin produces regularly a prompt relaxation of the sphincter muscle. After a variable interval, the duration of which depends on the dosage, the tonus recovers and may temporarily reach a level slightly higher than before the drug was given. On the other hand, if observations are made immediately after operating on the animal or if ether alone is used for anesthesia, the administration of adrenalin usually causes, immediately, a slight increase in the tonus of the sphincter.

No very pronounced changes in the tonus of the sphincter have been observed as a result of administering adrenalin. The greatest increase in tonus obtainea with adrenalin was much less than that which results from morphin, or from vagus stirnulation. When a decrease in tonus is obtained it is generally somewhat more pronounced, but is decidedly less than is seen in the small intestine when adrenalin is given.

Although Gruber and others have found that adrenalin may contract or relax gastrointestinal muscle, depending on the dosage, no such influence of dosage is apparent in the results of these experiments so far, but further study of this point seems desirable.