Document Detail

Propranolol increases the complexity of heart rate fluctuations--a mode of antiarrhythmic action?
MedLine Citation:
PMID:  15726879     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: To study the beta-blocking effect of propranolol on heart rate and arterial blood pressure fluctuations in healthy subjects using linear methods and a set of nonlinear models. METHODS: In a randomized, double-blind, placebo-controlled study, healthy young adults received a 40 mg oral dose of propranolol (n = 12) or placebo (n = 12). The effects of propranolol and placebo were assessed using time series of the RR interval (RRI) and systolic arterial blood pressure (SAP) obtained from continuous ECG and blood pressure signal recordings. Heart rate and systolic arterial blood pressure fluctuations were analyzed using nonlinear and linear methods of time series statistics. RESULTS: Propranolol significantly increased the complexity of heart rate fluctuations in terms of symbol dynamic (SymDyn) entropy and symbol dynamic percentage of forbidden words. Propranolol augmented cross entropy between RRI and SAP and increased fractal dimension of RRI. beta-blockade also affected linear measures of RRI fluctuations by increasing parasympathetic, respiration-related high-frequency (HF) variability and arterial baroreflex-related low-frequency (LF) variability. Propranolol administration, however, had no effect on the complexity of SAP fluctuations assessed using nonlinear time series statistics. CONCLUSIONS: beta-blockade by propranolol has a differential effect on RRI and SAP fluctuations in healthy subjects. Propranolol increases the complexity of RRI fluctuations. The effect is associated with the cardiac vagotonic drug action of propranolol. SAP fluctuations are almost unchanged. The increased complexity of RRI fluctuations may be a beneficial feature of beta-blockade, since many cardiovascular diseases decrease the complexity of RRI time series by dampening cardiovascular reflex actions.
A Lepoluoto; J Nino; K Tahvanainen; R Ylitalo; T Kuusela; M Kähönen; T Kaila
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Publication Detail:
Type:  Clinical Trial; Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  International journal of clinical pharmacology and therapeutics     Volume:  43     ISSN:  0946-1965     ISO Abbreviation:  Int J Clin Pharmacol Ther     Publication Date:  2005 Feb 
Date Detail:
Created Date:  2005-02-24     Completed Date:  2005-04-26     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  9423309     Medline TA:  Int J Clin Pharmacol Ther     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  101-8     Citation Subset:  IM    
Department of Pharmacological Sciences, University of Tampere, Finland.
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MeSH Terms
Administration, Oral
Adrenergic beta-Antagonists / administration & dosage,  pharmacology*
Arrhythmias, Cardiac / drug therapy*
Double-Blind Method
Heart Rate / drug effects*
Propranolol / administration & dosage,  pharmacology*
Reg. No./Substance:
0/Adrenergic beta-Antagonists; 0/Placebos; 525-66-6/Propranolol

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

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