Linked Life Data

1672857

Source:http://linkedlifedata.com/resource/pubmed/id/1672857

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5 Pt 1
pubmed:dateCreated
1991-5-13
pubmed:abstractText
The effects of dopamine on circular and longitudinal smooth muscle from the body of the guinea pig stomach were examined. In circular muscle, dopamine (10(-6)-10(-3) mol/L) induced contractions that were tetrodotoxin-insensitive with a concentration of half-maximal effect (EC50) of 6.3 x 10(-6) mol/L for dopamine vs. 1.4 x 10(7) mol/L for norepinephrine. The efficacies of dopamine- and norepinephrine-induced contraction were similar. The alpha-adrenoceptor antagonist phentolamine competitively inhibited dopamine-induced circular contractions (Ki = 2.5 x 10(-8) mol/L slope 1.06), whereas the dopamine antagonist haloperidol had no effect. The alpha 1-antagonist prazosin competitively inhibited dopamine-induced contractions (Ki = 1.8 x 10(-8) mol/L, slope 1.03), whereas the alpha 2 antagonist yohimbine was slightly less potent (Ki = 2.2 x 10(-7) mol/L, slope 1.15). In longitudinal muscle, dopamine produced relaxation with an EC50 of 2.9 x 10(-5) mol/L vs. 2.4 x 10(-6) mol/L for norepinephrine. Tetrodotoxin reduced relaxation to dopamine by one third at low doses of dopamine (10(-5)-10(-4) mol/L) and had no effect above 10(-3) mol/L. Phentolamine did not inhibit dopamine-induced relaxation, whereas haloperidol demonstrated potent competitive inhibition (Ki = 5.8 x 10(-7) mol/L, slope 0.90). The selective DA1 antagonist Sch 23390 (Research Biochemicals Inc., Natick, MA) showed competitive antagonism (Ki = 6.3 x 10(-6) mol/L, slope 0.98), whereas the selective DA2 antagonist domperidone had no effect. The effect of Sch 23390 was tetrodotoxin resistant. It is concluded that in the body of the guinea pig stomach, dopamine induces contraction in circular muscle through smooth muscle alpha adrenoceptors, whereas in longitudinal muscle, dopamine induces relaxation through smooth muscle DA1 receptors.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0016-5085
pubmed:author
pubmed:issnType
Print
pubmed:volume
100
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1224-31
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Characterization of receptors mediating the effects of dopamine on gastric smooth muscle.
pubmed:affiliation
Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor.
pubmed:publicationType
Journal Article, In Vitro