Document Detail

Assessing baroreflex gain from spontaneous variability in conscious dogs: role of causality and respiration.
MedLine Citation:
PMID:  11045994     Owner:  NLM     Status:  MEDLINE    
A double exogenous autoregressive (XXAR) causal parametric model was used to estimate the baroreflex gain (alpha(XXAR)) from spontaneous R-R interval and systolic arterial pressure (SAP) variabilities in conscious dogs. This model takes into account 1) effects of current and past SAP variations on the R-R interval (i.e., baroreflex-mediated influences), 2) specific perturbations affecting R-R interval independently of baroreflex circuit (e.g., rhythmic neural inputs modulating R-R interval independently of SAP at frequencies slower than respiration), and 3) influences of respiration-related sources acting independently of baroreflex pathway (e.g., rhythmic neural inputs modulating R-R interval independently of SAP at respiratory rate, including the effect of stimulation of low-pressure receptors). Under control conditions, alpha(XXAR) = 14.7 +/- 7.2 ms/mmHg. It decreases after nitroglycerine infusion and coronary artery occlusion, even though the decrease is significant only after nitroglycerine, and it is completely abolished by total arterial baroreceptor denervation. Moreover, alpha(XXAR) is comparable to or significantly smaller than (depending on the experimental condition) the baroreflex gains derived from sequence, power spectrum [at low frequency (LF) and high frequency (HF)], and cross-spectrum (at LF and HF) analyses and from less complex causal parametric models, thus demonstrating that simpler estimates may be biased by the contemporaneous presence of regulatory mechanisms other than baroreflex mechanisms.
A Porta; G Baselli; O Rimoldi; A Malliani; M Pagani
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  279     ISSN:  0363-6135     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2000 Nov 
Date Detail:
Created Date:  2000-11-17     Completed Date:  2000-12-28     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H2558-67     Citation Subset:  IM    
Dipartimento di Scienze Precliniche, Laboratorio Interdisciplinare Tecnologie Avanzate di Vialba, Universitá degli Studi di Milano, 20157 Milan, Italy.
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MeSH Terms
Arteries / physiology
Baroreflex / physiology*
Blood Pressure / physiology
Consciousness / physiology*
Heart Rate / physiology
Models, Cardiovascular*
Reproducibility of Results

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

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