norepinephrine


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Related to norepinephrine: dopamine, serotonin

norepinephrine

norepinephrine (nôrˌĕpīnĕfˈrən), a neurotransmitter in the catecholamine family that mediates chemical communication in the sympathetic nervous system, a branch of the autonomic nervous system. Like other neurotransmitters, it is released at synaptic nerve endings to transmit the signal from a nerve cell to other cells. Norepinephrine is almost identical in structure to epinephrine, which is released into the bloodstream from the adrenal medulla under sympathetic activation. The sympathetic nervous system functions in response to short-term stress; hence norepinephrine and epinephrine increase the heart rate as well as blood pressure. Other actions of norepinephrine include increased glycogenolysis (the conversion of glycogen to glucose) in the liver, increased lipolysis (the conversion of fats to fatty acids; see fats and oils) in adipose (fat) tissue, and relaxation of bronchial smooth muscle to open up the air passages to the lungs. All of these actions represent a mobilization of the body's resources in order to meet the stressful challenge—such a response is often termed the “flight or fight” syndrome.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Norepinephrine

 

(also noradrenaline, arterenol, 3,4-dihydroxyphenylethanolamine), a biologically active catecholamine. Norepinephrine has the following structure:

In animals and man, norepinephrine is in part produced by the chromaffin cells of the adrenal medulla, but it is mostly secreted by the adrenergic nerve elements of the sympathetic nervous system, where it serves as a chemical transmitter, or mediator substance, in nerve excitation. Judging by its action on the heart, blood vessels, smooth muscles, and carbohydrate metabolism, norepinephrine possesses the properties of hormones and is similar to its N-methyl derivative—adrenaline. The level of norepinephrine in the blood, organs, and excretions of the body is an indicator of the tone and reactivity of the sympathetic nervous system.

Norepinephrine can be produced synthetically. It is used in medicine to treat such conditions as low blood pressure, collapse, shock, and hemorrhage.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

norepinephrine

[‚nȯr·ep·ə′ne·frən]
(biochemistry)
C8H11O3N A hormone produced by chromaffin cells of the adrenal medulla; acts as a vasoconstrictor and mediates transmission of sympathetic nerve impulses. Also known as noradrenaline.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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