THE INTERACTION OF ACETYLCHOLINE, EPINEPHRINE AND CERTAIN OTHER DRUGS ON THE ISOLATED SMALL INTESTINE OF THE RAT

¹ From the Department of Physiology and Pharmacology, Duke University Medical School, Durham, North Carolina

1. There is a reciprocal quantitative antagonism between acetylcholine and epinephrine on the isolated small intestine of the rat. The significance of this is discussed.

2. The upper part of the small intestine is much less sensitive to epinephrine than the lower. On the other hand, the upper part is more sensitive to nicotine, cocaine and amyl nitrite.

3. Histamin is entirely without action on the rat intestine but barium acts normally indicating that the muscle can be stimulated directly.

4. Pilocarpine does not act very effectively. Epinephrine, cocaine, and nicotine cause much greater relaxation of an intestinal strip contracted with pilocarpine than one contracted with acetylcholine or barium.