Linked Life Data

1984874

Source:http://linkedlifedata.com/resource/pubmed/id/1984874

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1991-2-7
pubmed:abstractText
The mechanism by which isoproterenol (ISO) prevents the prolongation of action potential duration (APD) and refractory period (RP) by the class III antiarrhythmic agent E-4031 was studied. E-4031 (1 microM) increased RP by 50% with no effect on contractile force in papillary muscles isolated from guinea pig heart. ISO (1 microM) increased force of contraction more than fivefold and decreased RP by 25%. The prolongation of RP by E-4031 was prevented by pretreatment of muscles with ISO. The prolongation of APD in isolated guinea pig ventricular myocytes by 5 microM E-4031 also was antagonized by prior exposure of the cells to 1 microM ISO. Instantaneous currents and delayed rectifier K+ currents, IK, were measured in isolated myocytes using the suction microelectrode voltage-clamp technique. Currents were measured in response to 225-msec depolarizing pulses from a holding potential of -40 mV. Previous studies have demonstrated that IK in these cells results from activation of two distinct outward K+ currents, IKs and IKr (specifically blocked by E-4031). ISO doubled the magnitude of IKs without significant effect on IKr. The instantaneous current, putatively identified as a Cl- current, also was doubled by ISO but was unaffected by E-4031. The augmented conductance of IKs and instantaneous current by ISO results in a decrease in RP. The small effect of E-4031 on APD and RP in the presence of ISO results from the smaller contribution of IKr relative to the augmented repolarizing currents.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0009-7330
pubmed:author
pubmed:issnType
Print
pubmed:volume
68
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
77-84
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Isoproterenol antagonizes prolongation of refractory period by the class III antiarrhythmic agent E-4031 in guinea pig myocytes. Mechanism of action.
pubmed:affiliation
Merck Sharp & Dohme Research Laboratories, Department of Pharmacology, West Point, Pa 19486.
pubmed:publicationType
Journal Article, In Vitro