Linked Life Data

2996558

Source:http://linkedlifedata.com/resource/pubmed/id/2996558

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
20
pubmed:dateCreated
1985-11-13
pubmed:abstractText
The conducting system of the heart has been reported to be more sensitive to the toxic effects of digitalis than the working myocardium. To investigate the molecular basis of these observations, we have characterized the ouabain receptor in Purkinje fibres and ventricular muscle of the digitalis-sensitive sheep heart using cell membrane preparations, crude homogenates and contracting heart tissues. [3H]-Ouabain binding has the following characteristics: in sheep left ventricular cell membranes, specific binding was of high affinity (KD 1.9 X 10(-9) M at 37 degrees); was co-incident with an inhibition of (Na+ + K+)-ATPase activity; and was inhibited by K+ and unlabelled cardiotonic steroids; in crude homogenates, the maximal binding capacity but not the affinity for ouabain varied in different parts of the sheep heart with Purkinje fibres containing markedly fewer binding sites (0.33 X 10(14)/g wet weight; left ventricle, 1.3 X 10(14)/g wet weight) and in isolated, contracting Purkinje fibres and right ventricular moderator band strips, concentration-response curves for [3H]-ouabain binding, increase in force of contraction and inhibition of [86Rb+]-uptake were co-incident. In both contracting tissues, a ouabain concentration of 3 X 10(-7) M occupied about 50% of the specific binding sites, gave the maximal inotropic effect without toxicity and inhibited [86Rb+]-uptake by about 50%. The maximal binding capacity was lower in contracting Purkinje fibres (2 X 10(14) binding sites/g wet weight) than in contracting moderator band strips (3.9 X 10(14) binding sites/g wet weight). The maximal inotropic effects were reached slightly faster in Purkinje fibres but toxicity also occurred faster in these fibers. We conclude that the specific ouabain binding site is the receptor mediating positive inotropy and inhibition of (Na+ + K+)-ATPase in the sheep heart. Further, this receptor is identical in both the conducting system and working myocardium but the conducting system contains many fewer receptors. This change in receptor number, rather than affinity, may underlie the increased ouabain toxicity observed in Purkinje fibres.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-2952
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
34
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3701-10
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1985
pubmed:articleTitle
Comparison of ouabain receptors in sheep myocardium and Purkinje fibres.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't