Linked Life Data

6310363

Source:http://linkedlifedata.com/resource/pubmed/id/6310363

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1983-10-28
pubmed:abstractText
Angiotensin II binding sites in a rabbit ventricular myocardial particulate fraction were identified and characterized with the radioligand 125I-angiotensin II. The order of potency in competing with 125I-angiotensin II for these sites was similar to that observed in physiological studies. Computer-assisted analysis of the competition of binding sites for 0.3 nM 125I-angiotensin II by unlabeled angiotensin II (3 X 10(-11) M to 1 X 10(-5) M) demonstrated that optimal fitting of the competition curves was attained with a two-site model having one site of high affinity (KA1 = 2.4 +/- 0.6 X 10(9) M-1), low capacity (N1 = 7.8 +/- 0.8 fmoles/mg of protein) and a second site low affinity (KA2 = 9.6 +/- 0.6 X 10(6) M-1) and high capacity (N2 = 219 +/- 128 fmoles/mg of protein). Analysis of competition by Sar1-Ile8 angiotensin II for 125I-angiotensin II binding sites indicated that the antagonist interacted with the first site with high affinity (KA1 = 8 X 10(9) M-1), but interacted minimally with the second site (KA2 = 10(5) M-1). Monovalent cations (Na+, K+, Li+, NH4+) were roughly equipotent in decreasing 125I-angiotensin II binding by reducing the number of high-affinity sites (N1 = 2.6 +/- 0.7 fmoles/mg of protein with 100 mM Na+) without changing the affinity of either site or the number of low-affinity sites. The number of high-affinity sites was increased to 14.4 +/- 1.5 fmoles/mg of protein by 5 mM Mg2+. In the presence of divalent cations, nucleotides reduced binding of 125I-angiotensin II with the potency order guanosyl-5'-yl-imidodiphosphate greater than GTP greater than GDP greater than ATP greater than GMP. Guanosyl-5'yl-imidodiphosphate significantly reduced the affinity of the high-affinity site (KA1 = 1.0 +/- 0.2 X 10(9) M-1) and perhaps of the low-affinity site (KA2 = 1.0 +/- 2.2 X 10(6) M-1). Computer-assisted assessment of dissociation of 0.3 nM 125I-angiotensin II from rabbit myocardial membranes corroborated the equilibrium data: dissociation was biphasic (K-1 = 0.19 +/- 0.2 min-1 for a rapidly dissociating site, k-1 = 2.5 +/- 2.1 X 10(-3) min-1 for a slowly dissociating site); 5 mM Mg2+ did not significantly change either dissociation rate; but guanosyl-5'-yl-imidodiphosphate significantly increased dissociation rates from both sites. Despite the indirect evidence that these angiotensin II receptors interact with guanine nucleotide regulatory proteins, angiotensin II (10(-6) M) failed to influence adenylate cyclase activity. The physiological implications of the presence in ventricular myocardium of two distinct angiotensin II receptors and in particular the implications of a receptor-associated guanine nucleotide regulatory protein which does not couple to adenylate cyclase require further investigation.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0026-895X
pubmed:author
pubmed:issnType
Print
pubmed:volume
24
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
213-21
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1983
pubmed:articleTitle
Characterization of the rabbit ventricular myocardial receptor for angiotensin II. Evidence for two sites of different affinities and specificities.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't