Document Detail

Glucagon increases contractility in ventricle but not in atrium of the rat heart.
MedLine Citation:
PMID:  18474367     Owner:  NLM     Status:  MEDLINE    
This study evaluates the inotropic responses to glucagon in electrically driven isolated left and right atria as well as in right ventricular strips of rat heart. For comparison, the contractile effects resulting from stimulating beta-adrenoceptors with isoprenaline in atrial and ventricular tissues were also obtained. Glucagon (0.01-1 microM) produces a concentration-dependent positive inotropic effect in ventricular but not in atrial myocardium. Isoprenaline, however, increases contractility both in atrial and ventricular tissues. The nonselective phosphodiesterase (PDE) inhibitor 3-isobutylmethylxantine (IBMX, 10 microM) enhances the contractile effect of glucagon on ventricular myocardium. However, glucagon still failed to increase contractility in atrial myocardium in the presence of 10 microM, IBMX. Also, in left atria of rats pretreated with pertussis toxin, glucagon did not produce any positive inotropic effect, either alone or in the presence of 10 microM, IBMX. Western blotting analysis indicates that glucagon receptors expression is 5 times higher in ventricular than in atrial myocardium. Taken together, these results indicate that the lack of inotropic effect of glucagon in atrium is not due to Gi protein or PDEs activity but seems to be a consequence of a lower glucagon receptor density in this tissue.
Carmen Gonzalez-Muñoz; Susana Nieto-Cerón; Juan Cabezas-Herrera; Jesús Hernández-Cascales
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-04-08
Journal Detail:
Title:  European journal of pharmacology     Volume:  587     ISSN:  0014-2999     ISO Abbreviation:  Eur. J. Pharmacol.     Publication Date:  2008 Jun 
Date Detail:
Created Date:  2008-06-02     Completed Date:  2008-08-25     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  1254354     Medline TA:  Eur J Pharmacol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  243-7     Citation Subset:  IM    
Department of Pharmacology, Medical School, University of Murcia, Spain.
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MeSH Terms
1-Methyl-3-isobutylxanthine / pharmacology
Actins / metabolism
Blotting, Western
Cardiotonic Agents / pharmacology
Electric Stimulation
Glucagon / pharmacology*
Heart / drug effects*
Heart Atria / drug effects
Heart Ventricles / drug effects
Isoproterenol / pharmacology
Myocardial Contraction / drug effects*
Pertussis Toxin / pharmacology
Phosphodiesterase Inhibitors / pharmacology
Rats, Sprague-Dawley
Reg. No./Substance:
0/Actins; 0/Cardiotonic Agents; 0/Phosphodiesterase Inhibitors; 28822-58-4/1-Methyl-3-isobutylxanthine; 7683-59-2/Isoproterenol; 9007-92-5/Glucagon; EC Toxin

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