Document Detail


Acute intravenous cocaine causes transient depression followed by enhanced left ventricular function in conscious dogs.
MedLine Citation:
PMID:  8491024     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Prior studies in experimental canine models have demonstrated that intravenous cocaine administration causes myocardial depression. The purpose of the present study was to establish the mechanisms of cocaine's actions on myocardial and left ventricular performance after single intravenous bolus doses in conscious, chronically instrumented dogs, in which the full autonomic influences of cocaine would be manifest. METHODS AND RESULTS: In the intact state, cocaine (1 mg/kg) caused a transient decrease in left ventricular dP/dt (baseline; 3,086 +/- 107 mm Hg/sec; 2.5 minutes, 2,649 +/- 114 mm Hg; p < 0.05) followed by a 25 +/- 4% increase in left ventricular dP/dt that peaked at 15 minutes (left ventricular dP/dt, 3,751 +/- 127 mm Hg/sec, p < 0.01) and remained elevated during the 30-minute period of observation. Both the initial depression and the sustained increase in left ventricular contractile response were dose related. The increase in left ventricular dP/dt persisted under circumstances in which the responses were normalized for changes in heart rate and preload that accompanied cocaine administration. The positive inotropic effects were abolished by full autonomic or selective beta-adrenergic blockades. Finally, both cardiac output (baseline, 2,461 +/- 142 min/mL; peak [5 minutes], 3,434 +/- 218 mL/min; p < 0.05) and left ventricular stroke work (baseline, 39 +/- 5 g.m; peak, 49 +/- 6 g.m; p < 0.05) were increased at all times after cocaine administration, suggesting that pump performance was enhanced, despite early reductions in myocardial contractility. Similarly, indexes of early diastolic filling were enhanced despite transient early prolongation in isovolumic relaxation. CONCLUSIONS: Acute intravenous cocaine administration (0.1-2 mg/kg) has a biphasic effect on myocardial and left ventricular function with a transient depression followed by significant sustained increases in left ventricular contractility. The results are in keeping with an early local effect followed by significant adrenergic stimulation, which may be obscured by anesthesia or masked by changes in loading conditions.
Authors:
B S Stambler; K Komamura; T Ihara; R P Shannon
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Circulation     Volume:  87     ISSN:  0009-7322     ISO Abbreviation:  Circulation     Publication Date:  1993 May 
Date Detail:
Created Date:  1993-06-11     Completed Date:  1993-06-11     Revised Date:  2010-03-24    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1687-97     Citation Subset:  AIM; IM    
Affiliation:
Department of Medicine, Harvard Medical School, Beth Israel Hospital, Boston, Mass.
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MeSH Terms
Descriptor/Qualifier:
Animals
Autonomic Nerve Block
Cocaine / toxicity*
Diastole
Dogs
Female
Hemodynamics / drug effects
Injections, Intravenous
Male
Myocardial Contraction
Ventricular Function, Left / drug effects*
Grant Support
ID/Acronym/Agency:
HL-33107/HL/NHLBI NIH HHS; HL-38070/HL/NHLBI NIH HHS; RR-00168/RR/NCRR NIH HHS
Chemical
Reg. No./Substance:
50-36-2/Cocaine

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


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