Linked Life Data

2550131

Source:http://linkedlifedata.com/resource/pubmed/id/2550131

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1989-10-24
pubmed:abstractText
Little information is available about rate dependent changes in electrical activity of human myocardial cells. We therefore studied, in vitro, the electrical activity of adult human atrial fibres driven at frequencies near that of atrial flutter by means of the standard microelectrode technique. Thirty two atrial samples exhibiting "normal" responses with fast upstroke were selected. At very high frequencies, the action potential (AP) upstroke arose from the repolarisation phase of the preceding AP in spite of marked frequency induced shortening of the plateau. As the stimulation rate was progressively increased, the take off potential (TOP) was less and less negative and the maximal rate of depolarisation (Vmax) decreased. Moreover, in most preparations, a clear alternation between two types of action potentials occurred. Calcium channel inhibitors cobalt (5 mM) or diltiazem (5 x 10(-6) M) shortened AP duration, increased Vmax and markedly reduced alternation. Sodium channel inhibitors, tetrodotoxin (7.5 10(-6) M) or lignocaine (10(-5) M) shortened AP duration and induced a transient increase in Vmax. Ouabain (10(-6) M) prolonged AP duration, decreased Vmax, enhanced alternation and finally suppressed the 1:1 capture of the atrial tissue. Our results show that, at high driving rates corresponding to the frequencies of atrial flutter, slight variations in action potential duration induced by drugs are associated with marked concomitant variations in Vmax and probably with consequent modifications of the conduction velocity.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0008-6363
pubmed:author
pubmed:issnType
Print
pubmed:volume
23
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
159-68
pubmed:dateRevised
2004-11-17
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Electrical activity of human atrial fibres at frequencies corresponding to atrial flutter.
pubmed:affiliation
Laboratoire de Physiologie Comparée associé au CNRS, Université Paris XI, Orsay, France.
pubmed:publicationType
Journal Article