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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
2
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pubmed:dateCreated |
1993-3-23
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pubmed:abstractText |
Radioligand binding studies have demonstrated that oxymetazoline has a high affinity for alpha-2A receptors, but lower affinities for alpha-2B and alpha-2C receptors. In contrast, prazosin has high affinity for alpha-2B and alpha-2C receptors, but relatively lower affinity for alpha-2A receptors. We exploited the respective selectivity of oxymetazoline and prazosin for alpha-2A and alpha-2B/2C adrenoceptors, respectively, to describe pharmacologically and to locate neuroanatomically alpha-2 adrenoceptor subtypes in the human brain. Competition curves for the inhibition of [3H]yohimbine binding by oxymetazoline and prazosin in homogenates of human caudate nucleus were fit best by a model assuming binding to two sites (P < .005). A concentration (CONCopt) of oxymetazoline and prazosin was calculated from these curves that would optimally antagonize binding of [3H]yohimbine to high-affinity sites, minimally inhibiting low-affinity binding. In the presence of CONCopt of prazosin, competition studies of remaining [3H]yohimbine binding in cerebral cortex revealed a rank order potency and potency ratios of compounds which were characteristic of alpha-2A receptors. In the presence of CONCopt of oxymetazoline, competition studies of remaining [3H]yohimbine binding in caudate revealed a rank order potency and potency ratios of compounds which were characteristic of alpha-2C receptors. The existence of a small population of alpha-2B adrenoceptors in the caudate could not be ruled out because slopes of competition curves of compounds which distinguish alpha-2B and alpha-2C adrenoceptors were shallow at oxymetazoline-insensitive sites. The percentages of [3H]yohimbine binding that were inhibited by the CONCopt of oxymetazoline and prazosin were determined in numerous brain regions. Oxymetazoline-sensitive binding of [3H]yohimbine predominated in most regions except for the caudate nucleus, where prazosin-sensitive binding was greatest.
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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Feb
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pubmed:issn |
0022-3565
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:volume |
264
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
967-76
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:8382286-Binding, Competitive,
pubmed-meshheading:8382286-Binding Sites,
pubmed-meshheading:8382286-Brain Chemistry,
pubmed-meshheading:8382286-Caudate Nucleus,
pubmed-meshheading:8382286-Humans,
pubmed-meshheading:8382286-Oxymetazoline,
pubmed-meshheading:8382286-Prazosin,
pubmed-meshheading:8382286-Receptors, Adrenergic, alpha,
pubmed-meshheading:8382286-Yohimbine
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pubmed:year |
1993
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pubmed:articleTitle |
Characterization of subtypes of alpha-2 adrenoceptors in the human brain.
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pubmed:affiliation |
Department of Psychiatry, Case Western Reserve University School of Medicine, Cleveland, Ohio.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
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