Linked Life Data

9257904

Source:http://linkedlifedata.com/resource/pubmed/id/9257904

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
1997-9-29
pubmed:abstractText
1. The whole-cell patch-clamp was used for studying the effects of various beta1- and beta2-adrenoceptor agonists and antagonists on the L-type Ca current (Ica) in frog ventricular myocytes. 2. Dose-response curves for the effects of isoprenaline (non selective beta-agonist), salbutamol (beta2-agonist), dobutamine (beta1-agonist) on ICa were obtained in the absence and presence of various concentrations of ICI 118551 (beta2-antagonist), metoprolol (beta1-antagonist) and xamoterol (partial beta1-agonist) to derive EC50 (i.e. the concentration of beta-agonist at which the response was 50% of the maximum) and Emax (the maximal response) values by use of a Michaelis equation. Schild regression analysis was performed to examine whether the antagonists were competitive and to determine the equilibrium dissociation constant (K(B)) for the antagonist-receptor complex. 3. Isoprenaline increased ICa with an EC50 of 20.0 nM and an Emax of 597%. ICI 118551 and metoprolol competitively antagonized the effect of isoprenaline with a K(B) of 3.80 nM and 207 nM, respectively. 4. Salbutamol increased ICa with an EC50 of 290 nM and an Emax of 512%. ICI 118551 and metoprolol competitively antagonized the effect of salbutamol with a K(B) of 1.77 nM and 456 nM, respectively. 5. Dobutamine increased ICa with an EC50 of 2.40 microM and an Emax of 265%. ICI 118551 and metoprolol competitively antagonized the effect of dobutamine with a K(B) of 2.84 nM and 609 nM, respectively. 6. Xamoterol had no stimulating effect on ICa. However, xamoterol competitively antagonized the stimulating effects of isoprenaline, salbutamol and dobutamine on ICa with a K(B) of 58-64 nM. 7. We conclude that a single population of receptors is involved in the beta-adrenoceptor-mediated regulation of ICa in frog ventricular myocytes. The pharmacological pattern of the response of ICa to the different beta-adrenoceptor agonists and antagonists tested suggests that these receptors are of the beta2-subtype.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0007-1188
pubmed:author
pubmed:issnType
Print
pubmed:volume
121
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1277-86
pubmed:dateRevised
2008-11-20
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Pharmacological characterization of the receptors involved in the beta-adrenoceptor-mediated stimulation of the L-type Ca2+ current in frog ventricular myocytes.
pubmed:affiliation
Laboratoire de Cardiologie Cellulaire et Moléculaire, INSERM U-446, Université de Paris-Sud, Faculté de Pharmacie, Chatênay-Malabry, France.
pubmed:publicationType
Journal Article, In Vitro, Research Support, Non-U.S. Gov't