antagonist

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antagonist

 [an-tag´o-nist]
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.

an·tag·o·nist

(an-tag'ŏ-nist),
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.

antagonist

(ăn-tăg′ə-nĭst)
n.
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.

an·tag′o·nis′tic adj.
an·tag′o·nis′ti·cal·ly adv.

antagonist

Anatomy
A muscle that opposes the movement of agonist muscles and returns a limb to its initial position.

Pharmacology
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.

an·tag·o·nist

(an-tag'ŏ-nist)
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.
Compare: synergist

antagonist

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.

Antagonist

A substance that tends to nullify the action of another.
Mentioned in: Withdrawal Syndromes

antagonist 

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.

an·tag·o·nist

(an-tag'ŏ-nist)
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
References in periodicals archive ?
With respect to NS1, viral strains from different animal hosts likely have NS1 genes adapted to antagonize the IFN[alpha]/[beta] system of their specific host species.
The value of native plant and animal species may still be unclear to western agriculturists but their preservation becomes mandatory in order to antagonize the risks of genetic erosion.
Tibi, a prolific scholar of Islam and Arab politics, repeatedly warns against the abuse of his argument: "we must never lose sight of the distinction between Islam and Islamic fundamentalism; any promotion of hostility to Islam itself in the guise of a clash of civilizations would unwittingly play into the hands of the fundamentalists in their efforts to antagonize the West" (p.
She still had hopes of being reinstated, and she feared that if she gave another interview she would further antagonize the company's management.
Since Aldus sued the Giunta press in 1507 and 1514 for their pirating of his titles, it would have made little sense for the Giunti to antagonize Aldus further by printing another of his titles.
"It is not the policy of government to antagonize other nation.
But as we've stated at the outset, it's best not to antagonize either.
The danger of an American-led Asian ''umbrella club,'' theoretically protected from any missiles - we say ''theoretically'' because of the technology's poor track record - is that it would unnecessarily isolate and antagonize China.
University of Otago (Dunedin, New Zealand) and Ludwig Institute for Cancer Research (New York, NY) have patented a method for using a viral VEGF-like protein from the orf virus strain NZ2 and from the orf virus strain NZ10 to bind to the extracellular domain of the VEGF receptor-2 to form bioactive complexes which mediate useful cellular responses and/or antagonize undesired biological activities.
These compounds can have profound effects, especially during critical periods of fetal and childhood development, because they mimic or antagonize the effects of sex hormones.
The victory margin would have been even larger if it included a number of Democrats in tough re-election races who were prepared to support PNTR but were given a pass by the White House so they wouldn't unnecessarily antagonize local unions by casting "yes" votes that weren't vital.
By virtue of its ability to antagonize a number of soilborne plant pathogens, B.