Résumé
Cholinomimetic Cholinergic agents are compounds which mimic the action of acetylcholine and/or butyrylcholine. In general, the word "choline" describes the various quaternary ammonium salts containing the N,N,N-trimethylethanolammonium cation. Found in most animal tissues, choline is a primary component of the neurotransmitter acetylcholine and functions with inositol as a basic constituent of lecithin. Choline also prevents fat deposits in the liver and facilitates the movement of fats into cells. The parasympathetic nervous system, which uses acetylcholine almost exclusively to send its messages, is said to be almost entirely cholinergic. Neuromuscular junctions, preganglionic neurons of the sympathetic nervous system, the basal forebrain, and brain stem complexes are also cholinergic, as are the receptor for the merocrine sweat glands. In neuroscience and related fields, the term cholinergic is used in these related contexts: A substance (or ligand) is cholinergic if it is capable of producing, altering, or releasing acetylcholine, or butyrylcholine ("indirect-acting"), or mimicking their behaviours at one or more of the body's acetylcholine receptor ("direct-acting") or butyrylcholine receptor types ("direct-acting"). Such mimics are called parasympathomimetic drugs or cholinomimetic drugs. A receptor is cholinergic if it uses acetylcholine as its neurotransmitter. A synapse is cholinergic if it uses acetylcholine as its neurotransmitter. Parasympathomimetic drug A molecule must possess a nitrogen atom capable of bearing a positive charge, preferably a quaternary ammonium salt. For maximum potency, the size of the alkyl groups substituted on the nitrogen should not exceed the size of a methyl group. The molecule should have an oxygen atom, preferably an ester-like oxygen capable of participating in a hydrogen bond. A two-carbon unit should occur between the oxygen atom and the nitrogen atom. There must be two methyl groups on the nitrogen A larger third alkyl group is tolerated but more than one large alkyl groups leads to loss of activity The overall size of the molecule cannot be altered much.
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