acetylcholine


acetylcholine
acetylcholinic /euh seet'l koh lin"ik, euh set'-, as'i tl-/, adj.
/euh seet'l koh"leen, euh set'-, as'i tl-/, n.
1. Biochem. the acetic acid ester of choline, C7H17NO3, released and hydrolyzed during nerve conduction and causing muscle action by transmitting nerve impulses across synapses.
2. Pharm. this substance used in its chloride form in eye surgery. Abbr.: ACh
[1905-10; ACETYL + CHOLINE]

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Ester of choline and acetic acid, a neurotransmitter active at many nerve synapses and at the motor end plate of vertebrate voluntary muscles.

It affects several of the body's systems, including the cardiovascular system (decreases heart rate and contraction strength, dilates blood vessels), gastrointestinal system (increases peristalsis in the stomach and amplitude of digestive contractions), and urinary system (decreases bladder capacity, increases voluntary voiding pressure). It also affects the respiratory system and stimulates secretion by all glands that receive parasympathetic nerve impulses (see autonomic nervous system). It is important in memory and learning and is deficient in the brains of those with late-stage Alzheimer disease.

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      (ACh), an ester of choline and acetic acid that is the transmitter (neurotransmitter) substance at many neural, or nerve, synapses and at the motor end plate of vertebrate muscles (see end-plate potential). When a nerve impulse arrives at the nerve ending, ACh, which is stored there in vesicles, is released and combines with a receptor molecule in the postsynaptic membrane or the end-plate membrane (end-plate potential) of a muscle fibre. This bonding changes the permeability of the membrane, and a change in the nature of a generator potential results. The effects of successive nerve impulses accumulate if they arrive at a sufficiently high frequency. The ACh is destroyed by an enzyme, acetylcholinesterase, and thus is effective only briefly. Inhibitors of the enzyme, however, prolong the lifetime of ACh itself.

      ACh affects a number of body systems including the cardiovascular system by acting as a vasodilator, by decreasing cardiac rate, and by decreasing cardiac contraction; the gastrointestinal system by such activities as increasing peristalsis in the stomach and by increasing the amplitude of digestive contractions; and the urinary tract by such actions as decreasing the capacity of the bladder and increasing the voluntary voiding pressure. It also affects the respiratory system and stimulates secretion by all glands that receive parasympathetic nerve impulses.

 ACh was first isolated around 1914; its functional significance was first established in about 1921 by Otto Loewi (Loewi, Otto), a German physiologist and later (1936) Nobel laureate. Loewi demonstrated that ACh is the substance liberated when the vagus nerve is stimulated, causing slowing of the heartbeat. Subsequently he and others showed that ACh is also liberated as a transmitter at the motor end plate of striated (voluntary) muscles of vertebrates, and it has since been identified as a transmitter at many neural synapses and in many invertebrate systems as well.

      ACh is also known to play an important role in memory and learning and is in abnormally short supply in the brains of those with Alzheimer's disease (Alzheimer disease).

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Universalium. 2010.

Look at other dictionaries:

  • Acetylcholine — IUPAC name …   Wikipedia

  • Acetylcholine — Acétylcholine Pour les articles homonymes, voir Ach. Acétylcholine …   Wikipédia en Français

  • ACÉTYLCHOLINE — L’acétylcholine (ACh) est l’ester acétique de la choline, corps basique azoté dérivé de l’ammonium quaternaire. Formule de l’acétylcholine: 廓 acétoxyéthyl triméthyl ammonium. L’ACh a été préparée par voie synthétique en 1867 et peut être obtenue… …   Encyclopédie Universelle

  • acetylcholine — n. 1. a neurotransmitter released by the transmitting dendron at autononmous synapses and at neuromuscular junctions. It is a quaternary amine with an obligatory negative counterion. The nominal formula for the hydroxide form is {C7H17NO3}.… …   The Collaborative International Dictionary of English

  • acetylcholine — acetylcholine. См. ацетилхолин. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • acetylcholine — [as΄i til΄kō′lēn] n. [ ACETYL + CHOLINE] the acetic acid ester of choline, (CH3) 3N(OH)CH2CH2OCOCH3, found in many body tissues, esp. at neuromuscular junctions, acting as a nerve impulse transmitter: its chloride or bromide is used in medicine… …   English World dictionary

  • Acétylcholine — Pour les articles homonymes, voir ACh. Acétylcholine …   Wikipédia en Français

  • acetylcholine — The acetic ester of choline, the neurotransmitter substance at cholinergic synapses, which causes cardiac inhibition, vasodilation, gastrointestinal peristalsis, and other par …   Medical dictionary

  • acetylcholine — n. the acetic acid ester of the organic base choline: the neurotransmitter released at the synapses of parasympathetic nerves and at neuromuscular junctions. After relaying a nerve impulse, acetylcholine is rapidly broken down by the enzyme… …   The new mediacal dictionary

  • acetylcholine — Acetyl ester of choline. Perhaps the best characterized neurotransmitter, particularly at neuromuscular junctions. ACh can be either excitatory or inhibitory, and its receptors are classified as nicotinic or muscarinic, according to their… …   Dictionary of molecular biology

  • acetylcholine — acetilcholinas statusas T sritis chemija formulė Formulę žr. priede. priedas( ai) Grafinis formatas atitikmenys: angl. acetylcholine rus. ацетилхолин ryšiai: sinonimas – 2 etanoiloksietiltrimetilamonis …   Chemijos terminų aiškinamasis žodynas


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