Muscarinic acetylcholine receptor  From Wikipedia, the free
encyclopedia Jump to: navigation, search Amanita muscaria, the
mushroom from which muscarine was isolated. Acetylcholine - the
natural agonist of muscarinic and nicotinic receptors. Muscarine
- an agonist used to distinguish between these two classes of
receptors. Not normally found in the body. Atropine - an
antagonist.  Muscarinic receptors, or mAChRs, are acetylcholine
receptors that form G protein-receptor complexes in the cell
membranes of certain neurons[1] and other cells. They play
several roles, including acting as the main end-receptor
stimulated by acetylcholine released from postganglionic fibers
in the parasympathetic nervous system.  Muscarinic receptors
were named as such because they are more sensitive to muscarine
than to nicotine.[2] Their counterparts are nicotinic
acetylcholine receptors (nAChRs), receptor ion channels that are
also important in the autonomic nervous system. Many drugs and
other substances (for example pilocarpine