Document Detail


Improvement of postreceptor events by metoprolol treatment in patients with chronic heart failure.
MedLine Citation:
PMID:  9316529     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVES: This study tested the hypothesis that metoprolol restores the reduction of the inotropic effect of the cyclic adenosine monophosphate (cAMP)-phosphodiesterase inhibitor milrinone, which is cAMP dependent but beta-adrenoceptor independent. BACKGROUND: Treatment with beta-adrenergic blocking agents has been shown to lessen symptoms and improve submaximal exercise performance and left ventricular ejection fraction in patients with heart failure. Restoration of the number of down-regulated beta-adrenoceptors has been suggested to be one mechanism of beta-blocker effectiveness. However, the reversal of postreceptor events, namely, an increase in inhibitory G-protein alpha-subunit concentrations, could also play a role. METHODS: Fifteen patients with heart failure due to dilated cardiomyopathy (left ventricular ejection fraction 24.6 +/- 1.5% [mean +/- SD], New York Heart Association functional class II or III) were treated with metoprolol (maximal dose 50 mg three times daily) for 6 months. Before and after metoprolol treatment, inotropic responses to milrinone (5 to 10 micrograms/kg body weight per min) were measured echocardiographically. For comparison, responses to milrinone were determined under control conditions and after accelerated application of 150 mg of metoprolol to inactivate beta-adrenoceptors in subjects with normal left ventricular function. RESULTS: In subjects with normal left ventricular function, treatment with metoprolol did not alter the increase in fractional shortening or pressure/dimension ratio of circumferential fiber shortening after application of milrinone. In patients with heart failure, treatment with metoprolol significantly increased left ventricular ejection fraction, fractional shortening and submaximal exercise tolerance and reduced heart rate, plasma norepinephrine concentrations and functional class. After metoprolol treatment, milrinone increased fractional shortening but had no effect before beta-blocker treatment. CONCLUSIONS: Milrinone increases inotropic performance independently of beta-adrenoceptors in vivo. Metoprolol treatment restores the blunted inotropic response to milrinone in patients with heart failure, indicating that postreceptor events (e.g., increase in inhibitory G-protein) are favorably influenced. This mechanism could contribute to the beneficial effects observed in the study patients and represents an important mechanism of how beta-blocker treatment influences the performance of the failing heart.
Authors:
M Böhm; H J Deutsch; D Hartmann; K L Rosée; A Stäblein
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Publication Detail:
Type:  Clinical Trial; Controlled Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of the American College of Cardiology     Volume:  30     ISSN:  0735-1097     ISO Abbreviation:  J. Am. Coll. Cardiol.     Publication Date:  1997 Oct 
Date Detail:
Created Date:  1997-10-30     Completed Date:  1997-10-30     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  8301365     Medline TA:  J Am Coll Cardiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  992-6     Citation Subset:  AIM; IM    
Affiliation:
Klinik III für Innere Medizin, Universität zu Köln, Cologne, Germany. michael.boehm@medizin.univ.koeln.de
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MeSH Terms
Descriptor/Qualifier:
Adrenergic beta-Antagonists / therapeutic use*
Adult
Aged
Cardiomyopathy, Dilated / complications
Cardiotonic Agents / therapeutic use*
Drug Synergism
Female
GTP-Binding Protein alpha Subunits, Gi-Go / drug effects
Heart Failure / drug therapy*,  etiology,  ultrasonography
Humans
Male
Metoprolol / therapeutic use*
Middle Aged
Milrinone
Myocardial Contraction / drug effects
Phosphodiesterase Inhibitors / therapeutic use*
Pyridones / therapeutic use*
Receptors, Adrenergic, beta / drug effects
Receptors, Cyclic AMP / drug effects
Stroke Volume / drug effects
Chemical
Reg. No./Substance:
0/Adrenergic beta-Antagonists; 0/Cardiotonic Agents; 0/Phosphodiesterase Inhibitors; 0/Pyridones; 0/Receptors, Adrenergic, beta; 0/Receptors, Cyclic AMP; 37350-58-6/Metoprolol; 78415-72-2/Milrinone; EC 3.6.5.1/GTP-Binding Protein alpha Subunits, Gi-Go

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


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