Linked Life Data

6644828

Source:http://linkedlifedata.com/resource/pubmed/id/6644828

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
1984-1-7
pubmed:abstractText
We used intracellular microelectrodes to study the electrophysiological effects of low barium concentrations (1--4 x 10(-5) M) on sheep cardiac Purkinje fibers. The main effect of barium was an increase in action potential duration (APD) both at -60 mV (APD-60) and at 100% repolarization (APD100). The prolongation of APD was greater at a lower (30/min) than at a higher driving rate (120/min). Barium significantly modified the normal linear relationship between driving rate and APD. The effects of barium on APD were enhanced by lowering [K+]0 and antagonized by increasing [Ca2+]0. Barium caused a slowing of phase 3 repolarization, a steepening of diastolic depolarization and induced spontaneous activity in the resting potential range during the interruption of the drive. The first spontaneous action potential was usually preceded by an oscillatory potential. By means of several procedures (lowering [K+]0, increasing [Ca2+]0, increasing the driving rate) it was possible to identify two separate mechanism underlying the initiation of spontaneous activity: (1) enhancement of normal diastolic depolarization and (2) induction of oscillatory afterpotentials. Finally, barium induced repetitive activity through early afterdepolarizations. We conclude that in Purkinje fibers low barium concentrations cause a lengthening of APD and can induce spontaneous activity by means of at least three different mechanisms. The main factor underlying the barium effects seems to be a reduction in potassium conductance.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0022-2828
pubmed:author
pubmed:issnType
Print
pubmed:volume
15
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
697-711
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1983
pubmed:articleTitle
Barium-induced spontaneous activity in sheep cardiac Purkinje cells.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't