Abstract
1. Adrenaline distinctly contracts the ileo-colic sphincter of the cat even in a small dose, and not only that of the intact animal but also the surviving sphincter; whilst the small intestine is relaxed and its movements arrested.
2. Pilocarpine exaggerates the tone of the sphincter greatly and increases its movement as in the small intestine.
3. Atropine acts similarly on the sphincter and the small intestine, i.e., a very small quantity of it does not act on the normal organs, whilst moderate and large doses (from 5 to 40 mgm. in a cat 2-4 kilo weight) cause augmented tone and movements. Very small quantities of atropine arrest the contractions caused by pilocarpine.
4. Cocaine increases the tone of the sphincter and has a tendency to cause spontaneous movements.
5. Nicotine causes marked relaxation of the surviving sphincter in the first stage and the normal movements then return. The balloon method carried out on the sphincter and the small intestine shows no difference between them, both undergoing strong contractions followed by inhibition and relaxation and finally returning to their normal activity.
6. The effects of atropine, pilocarpine, nicotine and cocaine on the sphincter are very similar to those on the intestine in general. Yet the innervation of the sphincter is entirely different from that of the intestine, in which the vagus is the augmentor, the splanchnic the depressor nerve, while in the sphincter the splanchnic is augmentor and no inhibitory nerve has been shown to exist. The correspondence in the action of these drugs on parts which are so different, suggests strongly that the seat of their activity is not the nervous apparatus, but the muscular. And this is strengthened by the fact that adrenaline has an action on the sphincter opposite from that in the intestine in general, thus changing along with the character of the nervous activity.
Footnotes
- Received March 1, 1916.
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