cholinesterase /cho·lin·es·ter·ase/ (-es´ter-ās) serum cholinesterase, pseudocholinesterase; an enzyme that catalyzes the hydrolytic cleavage of the acyl group from various esters of choline and some related compounds; determination of activity is used to test liver function, succinylcholine sensitivity, and whether organophosphate insecticide poisoning has occurred.
cholinesterase
cholinesterase (kō´lines´t
rās),
cholinesterase
true cholinesterase acetylcholinesterase.
cho·lin·es·ter·ase (k  l -n s t-r s, -rz)n. An enzyme that catalyzes the hydrolysis of choline esters chiefly at nerve terminals, where it hydrolyzes and inactivates acetylcholine. Also called acetylcholinesterase. |
cholinesterase
[kō′lines′tərās]
an enzyme that acts as a catalyst in the hydrolysis of acetylcholine to choline and acetate. It provides the off mechanism during cholinergic neurotransmission.
cholinesterase (kō´lines´t
rās),n an esterase that hydrolyzes acetylcholine. It is an enzyme that is widely distributed throughout the muscles, glands, and nerves of the body and that converts acetylcholine into choline and acetic acid.
cholinesterase
an enzyme that splits acetylcholine into acetic acid and choline. Called also acetylcholinesterase.
This enzyme is present throughout the body, but is particularly important at the neuromuscular junction, where the nerve fibers terminate. Acetylcholine is released when a nerve impulse reaches a neuromuscular junction. It diffuses across the synaptic cleft and binds to cholinergic receptors on the muscle fibers, causing them to contract. Cholinesterase splits acetylcholine into its components, thus stopping stimulation of the muscle fibers. The end products of the metabolism of acetylcholine are taken up by nerve fibers and resynthesized into acetylcholine.
cholinesterase inhibitor
the drugs neostigmine, physostigmine and pyridostigmine inhibit cholinesterase. These drugs are used to treat myasthenia gravis, a disease in which the cholinergic receptors are attacked by autoantibodies. The drugs extend the effect of acetylcholine on the muscle fiber.
cholinesterase reactivator
choline-reactivating oximes are effective antidotes in organophosphorus insecticide poisoning, a state of acetylcholine excess because of cholinesterase inhibition. 2-PAM (2-pyridine aldoxime methchloride) is the most popular oxime for this purpose.
cholinesterase
There are 2 cholinesterases: one is synthesized in the liver and present in the serum, and the other–now formally known as acetylcholinesterase—is synthesized in the RBCs; both are used to determine the extent of
organophosphate exposure; the serum form is more useful in detecting acute toxicity while acetylcholinesterase better reflects chronic exposure; some people have genetic variants of cholinesterase, which act more slowly on substrates than the normal
enzyme, and they may experience prolonged apnea after anesthesia with suxamethonium-type muscle relaxants; these variant enzymes can be detected by screening before undergoing anesthesia. See Dibucaine number. Cf Acetylcholinesterase.
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