Linked Life Data

21303662

Source:http://linkedlifedata.com/resource/pubmed/id/21303662

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2011-3-14
pubmed:abstractText
(Na(+)+K(+))-ATPase (NKA) mediates positive inotropy in the heart. Extensive studies have demonstrated that the reverse-mode Na(+)/Ca(2+)-exchanger (NCX) plays a critical role in increasing intracellular Ca(2+) concentration through the inhibition of NKA-induced positive inotropy by cardiac glycosides. Little is known about the nature of the NCX functional mode in the activation of NKA-induced positive inotropy. Here, we examined the effect of an NKA activator SSA412 antibody on (45)Ca influx in isolated rat myocytes and found that KB-R7943, a NCX reverse-mode inhibitor, fails to inhibit the activation of NKA-induced (45)Ca influx, suggesting that the Ca(2+) influx via the reverse-mode NCX does not mediate this process. Nifedipine, an L-type Ca(2+) channel (LTCC) inhibitor, completely blocks the activation of NKA-induced (45)Ca influx, suggesting that the LTCC is responsible for the moderate increase in intracellular Ca(2+). In contrast, the inhibition of NKA by ouabain induces 4.7-fold (45)Ca influx compared with the condition of activation of NKA. Moreover, approximately 70% of ouabain-induced (45)Ca influx was obstructed by KB-R7943 and only 30% was impeded by nifedipine, indicating that both the LTCC and the NCX contribute to the rise in intracellular Ca(2+) and that the NCX reverse-mode is the major source for the (45)Ca influx induced by the inhibition of NKA. This study provides direct evidence to demonstrate that the activation of NKA-induced Ca(2+) increase is independent of the reverse-mode NCX and pinpoints a mechanistic distinction between the activation and inhibition of the NKA-mediated Ca(2+) influx path ways in cardiomyocytes.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
1090-2104
pubmed:author
pubmed:copyrightInfo
Copyright © 2011 Elsevier Inc. All rights reserved.
pubmed:issnType
Electronic
pubmed:day
11
pubmed:volume
406
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
200-3
pubmed:meshHeading
pubmed:year
2011
pubmed:articleTitle
Mechanistic distinction between activation and inhibition of (Na(+)+K(+))-ATPase-mediated Ca2+ influx in cardiomyocytes.
pubmed:affiliation
Department of Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA. kxu002@umaryland.edu
pubmed:publicationType
Journal Article, Research Support, N.I.H., Extramural, Research Support, N.I.H., Intramural