Document Detail

Mechanical and neural contributions to hysteresis in the cardiac vagal limb of the arterial baroreflex.
MedLine Citation:
PMID:  17640929     Owner:  NLM     Status:  MEDLINE    
According to conventional wisdom, hysteresis in cardiac vagal baroreflex function exhibits a specific pattern: pressure falls are associated with longer heart periods and a smaller linear gain. A similar pattern occurs in the pressure-diameter relationship of barosensory vessels, and therefore it has been suggested that baroreflex hysteresis derives solely from vascular behaviour. However, we hypothesized that mechanical and neural baroreflex components contribute equally to baroreflex hysteresis. Blood pressure, carotid diameter and the electrocardiogram were recorded continuously during two trials of sequential bolus injections of nitroprusside and phenylephrine in 14 young healthy subjects. Baroreflex gain and its mechanical and neural components were estimated for falls and rises in pressure and diameter. The position or set point of the relations was quantified at the mean pressure and mean diameter. Gains were determined via piecewise linear regression. Set points and gains for falls versus rises in pressure and diameter were compared with the Chow test. Hysteresis was observed in all individuals, but not in every trial. In most, but not all, trials pressure falls were associated with longer heart periods and smaller linear gain, as conventional wisdom would predict. However, the pattern of hysteresis derived from the interaction of both mechanical and neural components. The two components most often acted in opposition to determine differences in set point, but in conjunction to determine differences in baroreflex gain. Therefore, we conclude that hysteresis is not solely determined by barosensory vessel behaviour but by the complex interaction of mechanical and neural aspects of the arterial baroreflex.
Péter Studinger; Richard Goldstein; J Andrew Taylor
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, N.I.H., Extramural     Date:  2007-07-19
Journal Detail:
Title:  The Journal of physiology     Volume:  583     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2007 Sep 
Date Detail:
Created Date:  2007-09-20     Completed Date:  2007-12-06     Revised Date:  2013-06-06    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  1041-8     Citation Subset:  IM    
Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA 02114, USA.
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MeSH Terms
Baroreflex / drug effects,  physiology*
Blood Pressure / drug effects,  physiology*
Carotid Arteries / innervation,  physiology*
Linear Models
Models, Cardiovascular
Nitroprusside / administration & dosage
Phenylephrine / administration & dosage
Reaction Time / physiology*
Vagus Nerve / physiology*
Vasoconstrictor Agents / administration & dosage
Vasodilator Agents / administration & dosage
Grant Support
Reg. No./Substance:
0/Vasoconstrictor Agents; 0/Vasodilator Agents; 15078-28-1/Nitroprusside; 59-42-7/Phenylephrine
Comment In:
J Physiol. 2008 Mar 1;586(5):1209-11   [PMID:  18187468 ]

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

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