Linked Life Data

6379149

Source:http://linkedlifedata.com/resource/pubmed/id/6379149

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1984-9-17
pubmed:abstractText
Modulation of the affinity of agonists and antagonists at muscarinic cholinergic receptors in rat heart membranes was investigated using the radiolabeled antagonist, [3H]quinuclidinyl benzilate ([3H]QNB), and the radiolabeled agonist, [methyl-3H]oxotremorine acetate ([3H]OXO). Receptor affinity for oxotremorine measured in competition binding assays with [3H]QNB or by equilibrium binding of [3H]OXO was increased when the incubation temperature was reduced to 4 degrees C. In contrast, the receptor affinity for [3H]QNB was decreased at lower incubation temperatures and a marked effect of guanine nucleotides on the affinity for [3H]QNB was revealed. Guanine nucleotides increased receptor affinity for [3H]QNB without changing the total number of binding sites. The GTP-induced increase in the affinity for [3H]QNB was reflected by an increase in the rate constant for association of [3H]QNB. At subsaturating ligand concentrations, guanine nucleotides increased [3H]QNB binding and decreased [3H]OXO binding with the same order of potency: GppNHp = GTP gamma S greater than GTP greater than guanosine 5'-diphosphate greater than GMP. Free Mg++ ion was required to observe guanine nucleotide effects on antagonist binding. Pretreatment of heart membranes with N-ethyl-maleimide increased [3H]QNB affinity and blocked the effects of guanine nucleotides. N-Ethylmaleimide also decreased [3H]OXO binding and increased [3H]QNB binding with a similar concentration-effect relationship. Thus, antagonist and agonist binding to muscarinic cholinergic receptors is modulated in a reciprocal manner by a number of factors; this modulation appears to reflect interaction of agonist and antagonist-occupied receptors with a guanine nucleotide regulatory protein, Ni.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0022-3565
pubmed:author
pubmed:issnType
Print
pubmed:volume
230
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
424-30
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1984
pubmed:articleTitle
Modulation of muscarinic cholinergic receptor affinity for antagonists in rat heart.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't