(n.) One who contends with another, especially in combat; an adversary; an opponent.
(n.) A muscle which acts in opposition to another; as a flexor, which bends a part, is the antagonist of an extensor, which extends it.
(n.) A medicine which opposes the action of another medicine or of a poison when absorbed into the blood or tissues.
(a.) Antagonistic; opposing; counteracting; as, antagonist schools of philosophy.
Example Sentences:
(1) This death is also dependent on the presence of chloride and is prevented with the non-selective EAA antagonist, kynurenic acid, but is not prevented by QA.
(2) Microionophoretically applied excitatory amino acids induced firing of extracellularly recorded single units in a tissue slice preparation of the mouse cochlear nucleus, and the similarly applied antagonist 2-amino-5-phosphonovalerate (2APV) was demonstrated to be a selective N-methyl-D-aspartate (NMDA) receptor antagonist.
(3) Meanwhile the efficiency of muscarinic antagonists in inhibition of tremor reaction induced by arecoline administration is associated with interaction between the drugs and the M2-subtype.
(4) The anticonvulsant properties of the endogenous excitatory amino acid antagonist, kynurenic acid (KYA), were studied in prepubescent and adult rats using the amygdaloid kindling model of epilepsy.
(5) A novel bicyclic prostaglandin analogue, (1S)-[1 alpha,2 alpha(Z),3 alpha,4 alpha]-7-[3-[(hexylthio)methyl]-7- oxabicyclo [2.2.1]hept-2-yl]-5-heptenoic acid ((-)-10), and its cogeners were found to be potent antagonists at the TxA2 receptor.
(6) This difference was abolished by exposure of the slices to propranolol, a beta-adrenergic receptor antagonist.
(7) The TxA2 antagonistic effects of KW-3635 were compared with that of daltroban in PRP from various animals species.
(8) In experiments performed to determine whether PtdIns(4,5)P2 hydrolysis induced by TRH may have been caused by the elevation of [Ca2+]i, the following results were obtained: the effect of TRH to decrease the level of PtdIns(4,5)P2 was not reproduced by the calcium ionophore A23187 or by membrane depolarization with 50 mM K+; the calcium antagonist TMB-8 did not inhibit the TRH-induced decrease in PtdIns(4,5)P2; and, most importantly, inhibition by EGTA of the elevation of [Ca2+]i did not inhibit the TRH-induced decrease in PtdIns(4,5)P2.
(9) Similarly, 50 microM D-600, a Ca+2 channel antagonist, significantly (P less than 0.01) reduced basal and 5-HETE-induced PRL release.
(10) Selective removal of endothelium had no effect on BK-induced contraction or the action of the antagonists.
(11) The second experiments entailed use of the nonspecific opiate antagonist, naloxone, as well as the specific delta antagonist, ICI 154,129, against seizures induced by icv-administered morphine, morphiceptin, DADL, or DSLET.
(12) These antagonists reverse NMDA-mediated long term influence in these brain areas.
(13) This novel mechanism of receptor regulation, named transmodulation, should be distinguished from the reduction in total receptor number caused by the homologous ligand (downregulation) and from the change in affinity produced by the binding of agonists or antagonists to the same receptor site.
(14) Furthermore, the ability of a vasopressin antagonist to lower arterial pressure in NTS hypertensive rats was markedly attenuated by clonidine treatment.
(15) All of the serotonergic antagonists studied had additional effects on the response of the coronary artery to electrical stimulation or to norepinephrine.
(16) Their receptive fields comprise a temporally and spatially linear mechanism (center plus antagonistic surround) that responds to relatively low spatial frequency stimuli, and a temporally nonlinear mechanism, coextensive with the linear mechanism, that--though broad in extent--responds best to high spatial-frequency stimuli.
(17) The effects of low doses of dihydropyridine (DHP) calcium channel antagonists nimodipine, nifedipine, (-)-R-202-791, and amlodipine, the DHP calcium channel agonist BAY K 8644 were investigated on clonic convulsions to pentylenetetrazole (PTZ) in mice.
(18) Addition in the cultures of 4-deoxypyridoxine, a potent antagonist of vitamin B6 coenzymes, concurrently with the mitogen, inhibits the induction of serine hydroxymethyltransferase.
(19) These results suggest that prevention of xenograft rejection using PAF-antagonist in association with other methods should be further investigated.
(20) The high concentrations of gonadotropins present in immature female rats by the end of the second week of life were suppressed by treatment with an antagonist against luteinizing hormone-releasing hormone (LHRH-A; Org.
Antagonize
Definition:
(v. t.) To contend with; to oppose actively; to counteract.
(v. i.) To act in opposition.
Example Sentences:
(1) Intrathecal injection of zopiclone potentiated morphine antinociception, while the intracerebroventricular injection of zopiclone failed to enhance morphine antinociception and the intracerebroventricular injection of flumazepil to antagonize the intraperitoneal-zopiclone-induced increase in morphine antinociception.
(2) of PLA2 caused marked degranulation of mast cells in the rat mesentery which was facilitated by addition of calcium ion (10 mM) but antagonized by pretreating with three antiinflammatory agents.
(3) [Ca2+]i exhibited a sigmoidal dependence on [Na+]o. Mg2+, a competitive inhibitor of Na2+-Ca2+ antiport in these cells, antagonized the increase in [Ca2+]i produced by lowering [Na+]o.
(4) Increases in extracellular calcium antagonized the negative inotropic effect.
(5) In K+-depolarized basilar arteries, ifenprodil competitively antagonized the response to Ca2+, and this was enhanced by pre-incubation in calcium hopantenate.
(6) During the postovulatory phase, endogenous progesterone and the production of metabolites antagonized this effect.
(7) An antagonism is unlikely when ciprofloxacin is combined with one of the beta-lactams studied or with tobramycin.
(8) Co-application of CGS 9896, a benzodiazepine receptor antagonist, did not antagonize the guanidino compound-induced inhibition of GABA responses.
(9) Aortic rings from the rabbit were similarly potently antagonized by the protein kinase C inhibitors, however, K(+)-induced contractions were also equally sensitive to these agents in both rat and rabbit tissues.
(10) The biphasic response to (-)-(S)-Bay K 8644 and (+)-(S)-202-791 suggests that the properties of Ca++ channel activation and antagonism may reside within a single 1,4-dihydropyridine molecule.
(11) We have investigated the bacterial antagonism exerted in oral secretion by alpha-hemolytic streptococci against S. aureus and S. epidermidis.
(12) The marine natural product lophotoxin has produced a non-reversible antagonism of parasympathetic and sympathetic functions that are known to be mediated by C6 sub-type nicotinic receptors.
(13) Strains showing occasional antagonism at a particular proportion of concentrations of the test combination, were found to only be indifferent when the mean index of the fractional inhibition concentration of all checkerboard combinations was calculated.
(14) The omission of glucose induced a marked increase in the efflux of [3H]GABA, which was antagonized by TTX (1 microM), but not by MK 801 (1 microM) or DNQX (100 microM).
(15) The hyperthermia in rabbits caused by the serotonergic stimulants cited above is also antagonized by pretreatment with MS.
(16) The neuroleptic agents haloperidol, fluphenazine, domperidone, sulpiride and tiapride also antagonized emesis induced by cisplatin but only a proportion of the animals were completely protected and diazepam and prednisolone only reduced the intensity of the response.
(17) These results suggest that formoterol modifies allergen-induced airway responses through functional antagonism rather than the inhibition of inflammatory cell infiltration.
(18) Depolarizations induced by acetyl-Arg6-septide, a NK1-receptor selective agonist, were also antagonized by spantide with a pA2 of 6.5.
(19) 5-Hydroxytryptamine contracted the musculature from all parts of the respiratory tract-an effect which was specifically antagonized by both methysergide and atropine.4.
(20) K showed little activity against LTC4 but could antagonize more selectively H- and ACh-mediated effects.