Linked Life Data

6142954

Source:http://linkedlifedata.com/resource/pubmed/id/6142954

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1984-5-21
pubmed:abstractText
Quantitative relationships between in vitro affinity for alpha 1- and alpha 2-adrenoceptors (specific binding sites in rat brain membranes of [3H]prazosin and [3H]clonidine, respectively) and in vitro and in vivo alpha 1/alpha 2-adrenoceptor agonist/antagonist activities were derived for a series of 11 alpha-adrenergic antagonists and 35 agonists of dissimilar chemical structure. For the antagonists, the alpha 1/alpha 2-binding selectivity ratio most significantly correlated with the functional alpha 1/alpha 2-blocking selectivity ratios assessed in vitro (rabbit isolated pulmonary artery: antagonism of alpha 1-adrenoceptor-induced vasoconstriction and alpha 2-adrenoceptor-evoked facilitation of transmitter release) and in vivo (antagonism of alpha 1- and alpha 2-adrenoceptor-mediated vasoconstriction in pithed normotensive rats). These results show that the in vitro alpha 1- and alpha 2-adrenoceptor binding affinities of the antagonists provide adequate information concerning their functional alpha 1- and alpha 2-adrenoceptor blocking potencies against agonists. For the agonists, the central, alpha 2-adrenoceptor-elicited, hypotensive activity was not correlated with alpha 1-adrenoceptor binding affinity but was most significantly described in terms of affinity for alpha 2-adrenoceptors and a parabolic dependence on log P' (octanol/buffer; pH 7.4; 37 degrees C). The relevance of log P' in the regression is explained by the difference in accessibility to the membrane-bound alpha 2-adrenoceptors in the radioligand displacement experiments and the central medullary (hypotensive) alpha 2-adrenoceptors in the intact animal. In contrast, the affinity parameters for alpha 1- and alpha 2-adrenoceptors were found to be poor descriptors of the hypertensive potency of the agonists in which alpha 1- and alpha 2-adrenoceptors are known to play a role. The correlations in which the individual binding parameters and the combination of both variables were included reached only a moderate significance level.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0022-2623
pubmed:author
pubmed:issnType
Print
pubmed:volume
27
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
495-503
pubmed:dateRevised
2003-11-14
pubmed:meshHeading
pubmed:year
1984
pubmed:articleTitle
Quantitative relationships between alpha-adrenergic activity and binding affinity of alpha-adrenoceptor agonists and antagonists.
pubmed:publicationType
Journal Article