Study of two acetylcholine analogs with fixed conformations.

Two acetylcholine analogs, compound M (4,4-dimethyl-2-morpholonium) and compound P (1,1-dimethyl-3-acetoxypiperidinium) which contain the N-C-C-O group of acetylcholine fixed in the gauche and trans conformations, respectively, were tested for activity on the terminal ileum of the rat, the rectus abdominis muscle of the frog, and the superior cervical ganglion of the cat. It was found that compound M stimulates the ganglion but has no affinity for receptors in either the ileum or the rectus muscle, while compound P stimulates cholinergic receptors in the ileum and in the fast fibers of the rectus muscle but acts neither on the slow fibers of the rectus muscle nor on the ganglion.