FURTHER STUDIES ON THE EFFECT OF MORPHINE SULPHATE, ATROPINE SULPHATE, AND HYOSCINE HYDROBROMIDE UPON THE INTACT INTESTINE IN UNANESTHETIZED DOGS

¹ From the Department of Pharmacology, Washington University School of Medicine, Saint Louis, Missouri

1. In unanesthetized dogs, with a Thiry-Vella fistula, atropine sulphate can cause a decrease in tonus without decreasing simultaneously the height of rhythmical contractions.

2. Large doses of atrophie decrease the tonus and rhythmical contractions in a Thiry-Vella loop. This effect can be counter-acted by the injection of morphine (confirmation of Plant and Miller).

3. The increased tonus produced by the injection of morphine can be antagonized completely by a later injection of atropine sulphate.

4. After the general tonus was lowered by atropine, it could be brought back to the control level by the administration of morphine, but rarely above it. Conversely, atropine antagonized the increased tonus caused by a previous injection of morphine, and usually the general tonus reached a lower level than that of the control.

5. Hyoscine hydrobromide has the same effect upon the intact intestine of the unanesthetized dog as does atropine.

6. The increased tonus of the intestine caused by an injection of morphine could be antagonized by a later injection of hyoscine hydrobromide though this was found to be less efficient than atropine.

7. The decreased tonus caused by the previous injection of hyoscine could be abolished temporarily by an injection of morphine.