Linked Life Data

6129074

Source:http://linkedlifedata.com/resource/pubmed/id/6129074

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1983-2-25
pubmed:abstractText
The effects of endogenous and of exogenous norepinephrine were studied in isolated rings of canine left circumflex coronary artery and its first ventricular branch. Norepinephrine was released from adrenergic nerve endings by transmural electrical stimulation and by tyramine. In rings contracted with prostaglandin F2 alpha, transmural electrical stimulation resulted in frequency-dependent relaxations which were blocked by propranolol or tetrodotoxin; tyramine and exogenous norepinephrine caused concentration-dependent relaxations which were blocked by propranolol. The tyramine-induced relaxations also were inhibited by cocaine. The left circumflex artery was less sensitive than its branch to beta-adrenergic activation; this difference was significant even between rings of the two vessels immediately adjacent to the branching point and was abolished by phentolamine. In the presence of propranolol, transmural electrical stimulation, tyramine and phenylephrine, produced contractions of the left circumflex artery, but not the branch; these contractions were prevented by phentolamine. Phentolamine, but not prazosin, augmented the beta-adrenergic response of left circumflex artery to low frequency stimulation; in arteries preincubated with 3H-norepinephrine, this was accompanied by an increased overflow of tritiated neurotransmitter. The prejunctional effect of phentolamine was also evident in branch coronary arteries which exhibit no postjunctional alpha-adrenergic responses. With high frequency stimulation, both alpha-adrenergic antagonists equally augmented the relaxation of left circumflex artery; the efflux of tritiated norepinephrine was not different from untreated arteries. These experiments demonstrate, in isolated coronary arteries, that the primary adrenergic response to released endogenous norepinephrine is beta-adrenergic relaxation. The prejunctional effects of nonspecific alpha-adrenergic antagonists preclude their use in determining the importance of postjunctional coronary alpha-adrenergic receptor activation caused by sympathetic nerve stimulation.
pubmed:grant
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
52
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
16-25
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1983
pubmed:articleTitle
Prejunctional and postjunctional actions of endogenous norepinephrine at the sympathetic neuroeffector junction in canine coronary arteries.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't