(1) The hypothesis that opiate agonism requires an N substituent in the axial position does not appear to be consistent with the increased potency of beta isomers in which axial N substituents are thermodynamically more unstable.
(2) Under conditions of 5-HT1-like, 5-HT2 and 5-HT3 receptor blockade, the following rank order of agonism was observed: 5-HT > 5-methoxytryptamine = renzapride > (S)-zacopride > (R,S-zacopride > 5-carboxamidotryptamine > BRL 24682 > (R-zacopride > metoclopramide > 2-methyl-5-HT > sulpiride.
(3) At the agonal stage, the isoproterenol dose-response curve was shifted significantly to the right in myocardial membranes from endotoxic rats, but there was no significant decrease in maximum stimulated activity.
(4) Agonal state effects the stability of brain compounds and causes brain hypoxia.
(5) However, further studies showed compounds which exhibited either partial agonism in the RFA and competitive antagonism of 5-HT in the RA, or antagonism of 5-HT in both arteries with different affinities.
(6) Catecholamines were detectable in the major neurons, in small intensely fluorescent cells, and in adrenergic fibers with varicosities at levels that varied with the patient's age, cause of death, duration of the agonal period, the treatment administered, and the time when the material had been taken after death.
(7) Certain derivatives of the antagonists naloxone and naltrexone showed partial agonism.
(8) Except for desGly(NH2)AVP, which is a weak V2 agonist, the remaining desGly and desGly(NH2) analogues of 1-3 exhibit substantial V2 agonism and are thus highly selective V2 agonists.
(9) But bureaucratic dysfunction means less than half have been given out – as shown by two state department charts – and only at the end of agonizingly long waiting periods .
(10) The results failed to support the female agonism hypothesis and indicate a need for more detailed studies of intermale social dynamics.
(11) In the inferior parietal cortex, agonal status confounded this comparison.
(12) Dilevalol is a novel antihypertensive agent combining vasodilation due to selective beta 2-adrenergic receptor agonism with nonspecific beta antagonism.
(13) The results indicate that alpha 2-adrenergic agonism with clonidine inhibits the bronchoconstriction induced by histamine.
(14) We have found no evidence of a physiologically relevant effect of serotonin agonism on osmoregulated vasopressin release, or on the ability of normal man to excrete a water load.
(15) The partial agonism of N alpha-guanylhistamine is related to the ability of the drug to bind with the receptor in two different modes with similar affinity.
(16) In contrast U50,488H produced biphasic curves characterized by a higher potency phase of agonism that was susceptible to antagonism by 16-methylcyprenorphine (RX8008M) and a lower potency phase that was apparently non-opioid in nature.
(17) As this profile of activity is not shared by the shorter-acting compound, salbutamol, it would seem that anti-inflammatory activity is associated with beta-adrenoceptor agonism of long duration.
(18) To clarify the regulation of duodenal motility, the aim of the present study was to investigate the effects of alpha-adrenoceptor agonism and blockade and of galanin on duodenal motility.
(19) Agonist-independent pA2 estimates for ICS 205-930 (6.3-6.6) suggest a single site of agonism.
(20) In addition, analyses of beta-adrenoceptor agonism and antagonism, using selective (beta 1: T-1583, beta 2: procaterol) and non-selective (isoproterenol) agonists as well as selective (beta 1: atenolol, beta 2: ICI 118,551) and non-selective (propranolol) antagonists, confirmed that beta-adrenoceptors in the canine facial vein are not homogeneous, with the beta 1-subtype predominating over the beta 2-subtype, and that the canine saphenous vein has a homogeneous population of the beta 2-subtype, as reported in the other species.
Antagonist
Definition:
(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.