Document Detail

Characterization of beta-adrenoceptors mediating relaxation of the guinea-pig ileum.
MedLine Citation:
PMID:  6149284     Owner:  NLM     Status:  MEDLINE    
Relaxation responses to sympathomimetic amines were recorded in potassium-contracted segments of guinea-pig ileum. Experiments were performed in the presence of phentolamine (5 X 10(-6) M) to eliminate beta-adrenoceptor-mediated effects. Metanephrine (10(-5) M) and desmethylimipramine (5 X 10(-7) M) were also present to prevent extraneuronal and neuronal uptake respectively. A potency order (-)-isoprenaline greater than (-)-noradrenaline greater than (-)-adrenaline was established, indicating a beta 1-adrenoceptor involvement for this relaxation. The potency of salbutamol (beta 2-selective) relative to isoprenaline in the ileum compared closely with its relative potency in isolated cardiac tissues (beta 1) but differed significantly from the value in lung parenchymal strips and vas deferens (beta 2). The pA2 values for antagonism of selective agonists (-)-noradrenaline (beta 1-selective) and fenoterol (beta 2-selective) by practolol (beta 1-selective) were identical, indicating a single beta 1-adrenoceptor population. The pA2 values for antagonism of these agonists by ICI 118,551 (beta 2-selective) were also identical and compatible with a beta 1-adrenoceptor population. Relaxation of the guinea-pig ileum is therefore mediated via a homogeneous population of beta 1-adrenoceptors.
P F Grassby; K J Broadley
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of pharmacy and pharmacology     Volume:  36     ISSN:  0022-3573     ISO Abbreviation:  J. Pharm. Pharmacol.     Publication Date:  1984 Sep 
Date Detail:
Created Date:  1984-12-20     Completed Date:  1984-12-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0376363     Medline TA:  J Pharm Pharmacol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  602-7     Citation Subset:  IM    
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MeSH Terms
Albuterol / pharmacology
Electric Stimulation
Guinea Pigs
Heart / drug effects
Ileum / drug effects
Isoproterenol / pharmacology
Lung / drug effects
Muscle Relaxation / drug effects
Muscle, Smooth / drug effects*
Norepinephrine / pharmacology
Potassium / pharmacology
Receptors, Adrenergic, beta / physiology*
Vas Deferens / drug effects
Reg. No./Substance:
0/Receptors, Adrenergic, beta; 18559-94-9/Albuterol; 51-41-2/Norepinephrine; 7440-09-7/Potassium; 7683-59-2/Isoproterenol

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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