THE ATROPINE-FAST NICOTINE STIMULATION OF THE RABBIT'S INTESTINE AND OF THE MUSCULARIS MUCOSAE OF THE DOGS INTESTINE

¹ Department of Pharmacology, Temple University School of Medicine Philadelphia 40, Pennsylvania

1. Nicotine stimulation of the rabbit's intestine (unlike intact segment of intestines of other animals) is insensitive to blockade by atropine. It has been confirmed that the action of nicotine on the muscularis mucosae of the dog's intestine is also atropine-fast.

2. Pharmacologic tests indicate that the actions of nicotine on the rabbit's intestine and the dog's muscularis mucosae are mediated by nerves.

3. Since the actions of nicotine were antagonized by atropine plus a sympatholytic agent only when these were present in concentrations far above the levels needed to inhibit the actions of large amounts of acetylcholine and epinephrine, respectively, it was concluded that the liberation of an adrenergic mediator did not account for these actions of nicotine.

4. Tests with anti-histamine agents, Banthine, and mephenesin did not suggest histamine or other agents as the potential mediator of nicotine stimulation of these intestinal preparations.

5. The relation of these results to the problem of the atropine-fastness of certain parasympathetic nerve actions and the possibility of another neurohumor to account for the several related phenomena are discussed.