Linked Life Data

10457095

Source:http://linkedlifedata.com/resource/pubmed/id/10457095

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
1999-12-21
pubmed:abstractText
1. The transient outward K+ current (Ito) is a major repolarizing ionic current in ventricular myocytes of several mammals. Recently it has been found that its magnitude depends on the origin of the myocyte and is regulated by a number of physiological and pathophysiological signals. 2. The relationship between the magnitude of Ito, action potential duration (APD) and Ca2+ influx (QCa) was studied in rat left ventricular myocytes of endo- and epicardial origin using whole-cell recordings and the action potential voltage-clamp method. 3. Under control conditions, in response to a depolarizing voltage step to +40 mV, Ito averaged 12.1 +/- 2.6 pA pF-1 in endocardial (n = 11) and 24.0 +/- 2.6 pA pF-1 in epicardial myocytes (n = 12; P < 0.01). APD90 (90 % repolarization) was twice as long in endocardial myocytes, whereas QCa inversely depended on the magnitude of Ito. L-type Ca2+ current density was similar in myocytes from both regions. 4. To determine the effects of controlled reductions of Ito on QCa, recordings were repeated in the presence of increasing concentrations of the Ito inhibitor 4-aminopyridine. 5. Inhibition of Ito by as little as 20 % more than doubled QCa in epicardial myocytes, whereas it had only a minor effect on QCa in myocytes of endocardial origin. Further inhibition of Ito led to a progressive increase in QCa in epicardial myocytes; at 90 % inhibition of Ito, QCa was four times larger than the control value. 6. We conclude that moderate changes in the magnitude of Ito strongly affect QCa primarily in epicardial regions. An alteration of Ito might therefore allow for a regional regulation of contractility during physiological and pathophysiological adaptations.
pubmed:commentsCorrections
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pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0022-3751
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
519 Pt 3
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
841-50
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Relationship between transient outward K+ current and Ca2+ influx in rat cardiac myocytes of endo- and epicardial origin.
pubmed:affiliation
I. Physiologisches Institut der Ruprecht-Karls Universität, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany. tilmann.volk@urz.uni-heidelberg.de
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't