acetylcholine

The acetic ester of choline, the neurotransmitter substance at cholinergic synapses, which causes cardiac inhibition, vasodilation, gastrointestinal peristalsis, and other parasympathetic effects. It is liberated from preganglionic and postganglionic endings of parasympathetic fibers and from preganglionic fibers of the sympathetic as a result of nerve injuries, whereupon it acts as a transmitter on the effector organ; it is hydrolyzed rapidly into choline and acetic acid by acetylcholinesterase in the tissues and by pseudocholinesterase in the blood.

- a. chloride a miotic, administered as an ophthalmic solution for parasympathomimetic effect; used in cataract surgery.

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ace·tyl·cho·line ə-.set-əl-'kō-.lēn, -.sēt-; .as-ə-.tēl- n a neurotransmitter C₇H₁₇NO₃ released at autonomic synapses and neuromuscular junctions, active in the transmission of nerve impulses, and formed enzymatically in the tissues from choline

ace·tyl·cho·lin·ic -kō-'lin-ik adj

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n.

the acetic acid ester of the organic base choline: the neurotransmitter released at the synapses of parasympathetic nerves and at neuromuscular junction. After relaying a nerve impulse, acetylcholine is rapidly broken down by the enzyme cholinesterase. anticholinergic drugs block the action of acetylcholine at receptor sites; anticholinesterase and acetylcholinesterase inhibitor prolong the activity of acetylcholine by blocking cholinesterase.

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ac·e·tyl·cho·line (ACh) (as″ə-təl-) (as″ə-tēl-koґlēn) a reversible acetic acid ester of choline; it is a cholinergic agonist and serves as a neurotransmitter at the myoneural junctions of striated muscles, at autonomic effector cells innervated by parasympathetic nerves, at the preganglionic synapses of the sympathetic and parasympathetic nervous systems, and at various sites in the central nervous system. ACh has few therapeutic applications owing to its diffuse action and rapid hydrolysis by acetylcholinesterase (AChE); synthetic derivatives are used for more specific, prolonged action. ACh is used as a vasodilator in pharmacoangiography, administered by intraarterial infusion.