antagonist(redirected from a-adrenergic antagonist)
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Related to a-adrenergic antagonist: Adrenergic agonist
antagonistic muscle. (see illustration.)
1. a substance that tends to nullify the action of another, as a drug that binds to a cellular receptor for a hormone, neurotransmitter, or another drug blocking the action of that substance without producing any physiologic effect itself. See also blocking agent.
2. a tooth in one jaw that articulates with one in the other jaw.
α-adrenergic antagonist alpha-adrenergic blocking agent.
β-adrenergic antagonist beta-adrenergic blocking agent.
folic acid antagonist see folic acid antagonist.
H1 receptor antagonist any of a large number of agents that block the action of histamine by competitive binding to the H1 receptor. Such agents also have sedative, anticholinergic, and antiemetic effects, the exact effect varying from drug to drug, and are used for the relief of allergic symptoms and as antiemetics, antivertigo agents, sedatives, and antidyskinetics in parkinsonism. This group is traditionally called the antihistamines.
H2 receptor antagonist an agent that blocks the action of histamine by competitive binding to the H2 receptor; used to inhibit gastric secretion in the treatment of peptic ulcer.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
Something opposing or resisting the action of another; certain structures, agents, diseases, or physiologic processes that tend to neutralize or impede the action or effect of others. Compare: synergist.
Farlex Partner Medical Dictionary © Farlex 2012
1. Physiology A muscle that counteracts the action of another muscle, the agonist.
2. A drug or chemical substance that interferes with the physiological action of another, especially by combining with and blocking its receptor.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
A muscle that opposes the movement of agonist muscles and returns a limb to its initial position.
A substance that partially or completely nullifies the effect of another agent; a chemical entity that is not naturally found in the body which occupies a receptor, produces no physiologic effects and prevents endogenous and exogenous chemicals from producing an effect on that receptor.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
Something opposing or resisting the action of another; any structure, agent, disease, or physiologic process that tends to neutralize or impede some action or effect.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
1. A muscle that acts to oppose the action of another muscle (the agonist).
2. A drug that counteracts or neutralizes the action of another drug. The antonym of antagonist is agonist.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
A substance that tends to nullify the action of another.
Mentioned in: Withdrawal Syndromes
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
1. An antagonistic muscle.
2. A substance (e.g. a drug, hormone or neurotransmitter) that depresses the action of an agonist or binds to a cell receptor without eliciting a physiological response (e.g. excitation or inhibition). Examples: atropine and hyoscine which block the effect of acetylcholine acting on cholinergic receptors and timolol which blocks adrenergic receptors. See agonist.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
Something opposing or resisting the action of another; certain structures, agents, diseases, or physiologic processes that tend to neutralize or impede the action or effect of others.
Medical Dictionary for the Dental Professions © Farlex 2012