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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
1
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pubmed:dateCreated |
1995-5-12
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pubmed:abstractText |
It has been suggested that agmatine (decarboxylated arginine) is an endogenous clonidine-displacing substance (CDS) which recognizes alpha 2-adrenoceptor and non-adrenoceptor, imidazoline binding sites. We have examined the effect of agmatine at alpha 2-adrenoceptor binding sites and pre- and postjunctional alpha 2-adrenoceptors. Agmatine produced a concentration-dependent inhibition of 1 nmol/l 3H-clonidine binding to both rat (pKi-5.10 +/- 0.05) and bovine (pKi-4.77 +/- 0.38) cerebral cortex membranes. However, agmatine (0.1-100 microM) failed to activate pre-junctional alpha 2-adrenoceptors regulating transmitter release in the guinea-pig isolated ileum and rat isolated vas deferens, nor did it activate postjunctional alpha 2-adrenoceptors of the porcine isolated palmar lateral vein which mediate contraction or inhibition of forskolin-stimulated cyclic AMP formation. High concentrations of agmatine (10-30-fold the pKi at alpha 2-adrenoceptor binding sites) failed to influence alpha 2-adrenoceptor activation by either clonidine or UK-14304 (5-bromo-6-[2-imidazolin-2-ylamino]-quinoxaline bitartrate) in any of the peripheral preparations examined. Moreover, even in a preparation where an interaction with alpha 2-adrenoceptor binding sites on cell membranes can be demonstrated, the rat cerebral cortex, agmatine failed to inhibit forskolin-stimulated cyclic AMP in the intact tissue or affect the inhibition produced by the selective alpha 2-adrenoceptor agonist UK-14304. Agmatine was also devoid of agonist activity in two preparations, the rat isolated thoracic aorta and the rat isolated gastric fundus, in which CDS has been reported to produce non-adrenoceptor effects. Thus, we have confirmed that agmatine recognizes alpha 2-adrenoceptor binding sites and, therefore, is a CDS.(ABSTRACT TRUNCATED AT 250 WORDS)
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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Adrenergic alpha-Agonists,
http://linkedlifedata.com/resource/pubmed/chemical/Agmatine,
http://linkedlifedata.com/resource/pubmed/chemical/Clonidine,
http://linkedlifedata.com/resource/pubmed/chemical/Cyclic AMP,
http://linkedlifedata.com/resource/pubmed/chemical/Quinoxalines,
http://linkedlifedata.com/resource/pubmed/chemical/Receptors, Adrenergic, alpha-2,
http://linkedlifedata.com/resource/pubmed/chemical/brimonidine
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pubmed:status |
MEDLINE
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pubmed:month |
Jan
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pubmed:issn |
0028-1298
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:volume |
351
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
10-6
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pubmed:dateRevised |
2010-8-25
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pubmed:meshHeading |
pubmed-meshheading:7715734-Adrenergic alpha-Agonists,
pubmed-meshheading:7715734-Agmatine,
pubmed-meshheading:7715734-Animals,
pubmed-meshheading:7715734-Binding, Competitive,
pubmed-meshheading:7715734-Binding Sites,
pubmed-meshheading:7715734-Clonidine,
pubmed-meshheading:7715734-Cyclic AMP,
pubmed-meshheading:7715734-Male,
pubmed-meshheading:7715734-Quinoxalines,
pubmed-meshheading:7715734-Radioligand Assay,
pubmed-meshheading:7715734-Rats,
pubmed-meshheading:7715734-Rats, Wistar,
pubmed-meshheading:7715734-Receptors, Adrenergic, alpha-2
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pubmed:year |
1995
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pubmed:articleTitle |
Agmatine recognizes alpha 2-adrenoceptor binding sites but neither activates nor inhibits alpha 2-adrenoceptors.
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pubmed:affiliation |
Department of Physiology and Pharmacology, Medical School, Queen's Medical Centre, Nottingham, UK.
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pubmed:publicationType |
Journal Article,
In Vitro,
Research Support, Non-U.S. Gov't
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