Linked Life Data

8062421

Source:http://linkedlifedata.com/resource/pubmed/id/8062421

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1994-9-20
pubmed:abstractText
In various mammalian species, shapes of action potentials vary within the cardiac wall because of differences in transient outward current (Ito). A prominent Ito exists in human ventricular myocytes, but cells have not been separated according to their original localization. Human ventricular myocytes were isolated from separated subepicardial and subendocardial tissue, and regional variations in Ito were studied. Ito was larger in subepicardial than subendocardial cells. Current density at +60 mV was 7.9 +/- 0.7 pA/pF (n = 28) in subepicardial cells and 2.3 +/- 0.3 pA/pF (n = 16) in subendocardial cells. When cells from explanted failing and nonfailing donor hearts were compared, Ito was not different in subepicardial cells; however, it was larger in subendocardial cells from nonfailing hearts. The potential of half-maximal activation (V0.5) was more positive in subendocardial cells (+25.6 +/- 3.5 mV, n = 15) than in subepicardial cells (+9.2 +/- 1.8 mV, n = 28). There was no difference in V0.5 between cells from failing and nonfailing hearts. Ito inactivation was similar in all cell types and independent of membrane depolarization (time constant [tau] = approximately 60 milliseconds at 22 degrees C). The potential of half-maximal steady-state inactivation was similar in all cell types. Recovery from inactivation of Ito was fast in subepicardial cells at -100 mV (tau = 24 +/- 4 milliseconds, n = 6), exceeding control values transiently (overshoot), and slow at -40 mV without overshoot (tau = 638 +/- 91 milliseconds, n = 6). In subendocardial cells, Ito recovered at -100 mV with a fast phase (tau = 25 milliseconds) and a slow phase (tau = 328 milliseconds), and recovery was not complete after 6 seconds at -100 mV. In conclusion, regional differences in Ito between subepicardial and subendocardial cells may have clinical implications with respect to rhythmic disturbance during heart failure.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0009-7330
pubmed:author
pubmed:issnType
Print
pubmed:volume
75
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
473-82
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Transient outward current in human ventricular myocytes of subepicardial and subendocardial origin.
pubmed:affiliation
Institut für Pharmakologie, Medizinische Einrichtungen der Universität-GH Essen, Germany.
pubmed:publicationType
Journal Article, Comparative Study