Acetylcholine (Ach) is produced by the synthetic enzyme choline acetyltransferase which uses acetyl coenzyme A and choline as substrates for the formation of acetylcholine.Dietary choline and phosphatidylcholine serve as the sources of free choline for acetylcholine synthesis. Upon release, acetylcholine is metabolized into choline and acetate by acetylcholinesterase, and other nonspecific esterases. Acetylcholine release can be excitatory or inhibitory depending on the type of tissue and the nature of the receptor with which it interacts. Cholinergic receptors can be divided into two types, muscarinic and nicotinic, based on the pharmacological action of various agonists and antagonists. Muscarinic receptors originally were distinguished from nicotinic receptors by the selectivity of the agonists muscarine and nicotine respectively.
-90912.jpg)