Document Detail


Baroreflex sensitivity and the blood pressure response to beta-blockade.
MedLine Citation:
PMID:  10204815     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The objective of this analysis was to determine whether changes in baroreflex sensitivity (BRS) within 35 hypertensive patients (25 M, 10 F, mean age 47 years) treated with beta-blockade as monotherapy relate to reductions in ambulatory blood pressure (BP) or its variability. BP was recorded intra-arterially directly from the brachial artery before and during submaximal exercise. BRS was determined by the phenylephrine injection technique. MAP and its variability were determined for the awake period of 24-h BP monitoring. Subjects were randomised to one of atenolol, metoprolol, pindolol, or propranolol, and restudied after a mean of 5 months. Beta-blockade increased BRS in 24 patients and decreased BRS in 11. BRS increased from 6.53+/-4.94 to 9.40+/-8.62 ms/mm Hg (mean +/- s.d.) (P<0.01). Waking ambulatory MAP decreased from 125.8+/-15.8 to 106.4+/-16.2 mm Hg (P<0.0001), but its variability did not change. Higher BRS after chronic beta-blockade was associated with a decrease in waking ambulatory MAP (r = -0.55, P<0.001), but not with its variability (r = -0.08). Beta-blockade attenuated the pressor response to exercise, but there was a positive relationship between the effect of beta-blockade on BRS, and on the rise in systolic BP during bicycling (r = 0.63; P<0.001). Any dampening effect of beta-blockade on BP variability at rest in hypertensive patients with the greatest increase in BRS may be offset by increased pressor responses to physical activity such as exercise. Consequently, BP variability is unaffected, even though reductions in ambulatory BP during chronic beta-blockade are inversely related to changes in BRS. BP responses to beta-blockade may be a function of the action of this class of drugs on BRS. However, there is considerable variation, between subjects, in their effect on BRS. This may have implications for other conditions, such as dilated cardiomyopathy, or following myocardial infarction, in which improvement in BRS is one mechanism by which beta-adrenoceptor blockade could improve survival.
Authors:
X Chen; M O Hassan; J V Jones; P Sleight; J S Floras
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Journal Article; Randomized Controlled Trial    
Journal Detail:
Title:  Journal of human hypertension     Volume:  13     ISSN:  0950-9240     ISO Abbreviation:  J Hum Hypertens     Publication Date:  1999 Mar 
Date Detail:
Created Date:  1999-06-03     Completed Date:  1999-06-03     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8811625     Medline TA:  J Hum Hypertens     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  185-90     Citation Subset:  IM    
Affiliation:
Department of Cardiovascular Medicine, University of Oxford, Canada.
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MeSH Terms
Descriptor/Qualifier:
Adolescent
Adrenergic alpha-Agonists / diagnostic use
Adrenergic beta-Antagonists / therapeutic use*
Adult
Aged
Atenolol / therapeutic use
Baroreflex / drug effects*
Blood Pressure / drug effects*
Exercise / physiology
Exercise Test
Female
Follow-Up Studies
Heart Rate / drug effects
Humans
Hypertension / drug therapy*,  physiopathology
Male
Metoprolol / therapeutic use
Middle Aged
Pindolol / therapeutic use
Prognosis
Propranolol / therapeutic use
Chemical
Reg. No./Substance:
0/Adrenergic alpha-Agonists; 0/Adrenergic beta-Antagonists; 13523-86-9/Pindolol; 29122-68-7/Atenolol; 37350-58-6/Metoprolol; 525-66-6/Propranolol

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


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