Document Detail

The inhibitory actions of amiodarone on rested-state contraction in isolated guinea-pig ventricular muscle.
MedLine Citation:
PMID:  2276588     Owner:  NLM     Status:  MEDLINE    
1. To assess the mechanism(s) of the negative inotropic effects of amiodarone (AM), an effective anti-arrhythmic agent, the effects of AM on rested-state contraction (RSC) were studied in isolated ventricular papillary muscle from control (untreated) and AM-pretreated guinea-pigs. 2. The RSC was induced by stimulation, following a 30 sec- or 10 min-rest period. 3. The drug's effects were evaluated on an initial response (Ti) and steady-state response (Tss) of the RSC at the end of 1 min-stimulus train at 3.3 Hz. 4. In normal physiological solution, the magnitude of Ti was 2.1 times that of Tss in papillary muscles from untreated animals, but, 1.3 times, in AM-pretreated ones. 5. The effects of superfused AM (4.4 x 10(-5)M) were also evaluated in both muscle types. 6. The drug markedly decreased Ti and Tss in both control and AM-pretreated specimens. 7. However, the depression by superfused AM of RSC in control specimens was more likely to be marked than in AM-pretreated ones. 8. Further, verapamil and caffeine, which affect SR function, also depressed the RSC. 9. These results suggest that the negative inotropic actions of AM, at least in part, reflect a decrease in Ca2+ via Ca2+ channels and an impairment of Ca2(+)-sequestrating system.
M Aomine
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  General pharmacology     Volume:  21     ISSN:  0306-3623     ISO Abbreviation:  Gen. Pharmacol.     Publication Date:  1990  
Date Detail:
Created Date:  1991-03-01     Completed Date:  1991-03-01     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7602417     Medline TA:  Gen Pharmacol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  709-14     Citation Subset:  IM    
Department of Medicine, Northwestern University Medical School, Chicago, IL 60611.
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MeSH Terms
Amiodarone / pharmacology*
Caffeine / pharmacology
Guinea Pigs
Myocardial Contraction / drug effects*
Papillary Muscles / drug effects
Verapamil / pharmacology
Reg. No./Substance:
1951-25-3/Amiodarone; 52-53-9/Verapamil; 58-08-2/Caffeine

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

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