Abstract
Summary
1. Prostigmine, acetylcholine, carbaminoyl-choline and acetyl-B-methyl-choline produce in Simocephalus vetulus vigorous intestinal contractions.
2. The period which elapses between the addition of the drugs and the onset of the characteristic effect is definitely dependent, with the exception of carbaminoyl-choline, on the concentration of the drug.
3. Carbaminoyl-choline did not exhibit a graded action within the range of concentrations employed in this work.
4. Atropine blocks the action of the drugs employed in this work. However, it acts more slowly and less effectively in antagonizing the action of carbaminoyl-choline.
5. Prostigmine causes intensification and prolongation of the effects of acetylcholine and it reduces considerably the time which elapses between the administration of acetylcholine and the appearance of the vigorous intestinal contractions.
6. In contrast with carbaminoyl-choline, a marked antagonism was found to exist between acetyl-B-methyl choline and atropine.
7. Carbaminoyl-choline differs from acetylcholine primarily in its greater stability and more powerful action.
8. The action of prostigmine, acetyl-choline, carbaminoyl-choline and acetyl-B-methyl-choline is remarkably similar in certain respects to the action ascribed to them on the digestive tube for a number of mammals.
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