Linked Life Data

1178063

Source:http://linkedlifedata.com/resource/pubmed/id/1178063

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1976-1-2
pubmed:abstractText
1. On guinea-pig papillary muscle we investigated whether a prolonging effect of noradrenaline on the duration of the cardiac ventricular action potential (AP) is attributable to an action on beta-adrenoceptors. 2. Propranolol (5 X 10(-6) M), which itself shortens AP (at 90% repolarization level), inhibits both effects of noradrenaline on the AP, i.e. the sustained prolongation by low concentrations (10(-7)--10(-6)M) and the steady-state shortening which follows an initial prolongation by a high concentration (10(-5)M). In the presence of propranolol, the prlonging effect of noradrenaline is shifted to higher concentrations (10(-6)--10(-5)M). This prolongation of AP duration does not exceed the prior shortening effect by propranolol; it is not prevented by 10(-5)M phentolamine. 3. Phentolamine, which itself prolongs AP duration, inhibits neither the initial prolongation nor the steady-state shortening of the AP by 10(-5)M noradrenaline. Instead, the biphasic change in AP duration as well as the positive inotropic effect of 10(-5)M noradrenaline are enhanced in the presence of 3Z10(-6)M phentolamine. 4. The effect of isoprenaline on the duration of AP qualitatively resembles that of noradrenaline. In a concentration of 10(-8)M, isoprenaline produces a sustained prolongation of the AP; concentrations of 10(-7)M and 10(-6)M cause an initial prolongation which is followed by a steady-state shortening. These effects are inhibited by propranolol. 5. It is concluded that not only the steady-state shortening effect on AP duration by 10(-5)M noradrenaline but also the prolongation of AP, induced by lower noradrenaline concentrations (10(-7)--10(-6)M), are mediated solely by an action on beta-adrenoceptors.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0028-1298
pubmed:author
pubmed:issnType
Print
pubmed:volume
288
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
403-14
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1975
pubmed:articleTitle
Adrenoceptors in cardiac ventricular muscle and changes in duration of action potential caused by noradrenaline and isoprenaline.
pubmed:publicationType
Journal Article, In Vitro