Document Detail


Attenuation of autonomic nervous system functions in hypertensive patients at rest and during orthostatic stimulation.
MedLine Citation:
PMID:  18256574     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effect of age on autonomic nervous system was assessed at rest and while standing using systolic blood pressure (SBP) and diastolic blood pressure (DBP), heart rate, and power spectral analysis of the time duration between 2 consecutive R waves of an electrocardiogram (RR) interval variability, as well as on plasma norepinephrine and epinephrine levels in mild to moderate hypertensive patients (DBP, 90-110 mm Hg). Patients younger than 60 years (n=57) and older than 60 years (n=32), were evaluated after a 3- to 4-week placebo period. Plasma catecholamines were measured in the supine position at rest and after 10 minutes of standing. Power spectral analysis of the RR interval variability was performed in each condition using the high-frequency (HF) band (0.15-0.4 Hz) as an index of parasympathetic activity and the low-frequency (LF) band (0.05-0.15 Hz) and LF-HF ratio to estimate sympathetic activity. The total power was calculated as the sum of LF and HF power. supine SBP was significantly higher in older patients (P<.05). SBP and DBP increased significantly only in younger patients during standing (P<.05), while the changes were smaller and nonsignificantly lower in older patients. HR was similar in both groups at rest and increased similarly during standing. Norepinephrine and epinephrine levels were similar at rest and increased similarly in both groups of patients during standing. At rest, lower LF and HF components were observed in older patients. The LF component increased less and the HF component decreased less in older patients during standing. A lower sympathetic and parasympathetic basal cardiac tone was observed at rest in older hypertensive patients. Moreover, reduced hemodynamic and sympathetic responses to standing as assessed by SBP, DBP, and the LF component of HR variability were observed in older hypertensives in the presence of a normal catecholamine response. These observations could reflect a decreased sensitivity of cardiac beta-adrenoceptors with aging.
Authors:
Maria Karas; Pierre Larochelle; Robert A LeBlanc; Bruno Dubé; Reginald Nadeau; Jacques de Champlain
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of clinical hypertension (Greenwich, Conn.)     Volume:  10     ISSN:  1524-6175     ISO Abbreviation:  J Clin Hypertens (Greenwich)     Publication Date:  2008 Feb 
Date Detail:
Created Date:  2008-02-07     Completed Date:  2008-04-16     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100888554     Medline TA:  J Clin Hypertens (Greenwich)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  97-104     Citation Subset:  IM    
Affiliation:
Institut de Recherches Cliniques de Montréal, Research Laboratory on the Autonomic Nervous System, Faculty of Medicine, Université de Montréal, Montréal, Canada.
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MeSH Terms
Descriptor/Qualifier:
Adolescent
Adult
Age Factors
Aged
Autonomic Nervous System / physiopathology*
Blood Pressure
Electrocardiography
Epinephrine / blood
Female
Heart Rate*
Humans
Hypertension / blood,  physiopathology*
Male
Middle Aged
Nordefrin / blood
Receptors, Adrenergic, beta / physiology
Severity of Illness Index
Supine Position
Chemical
Reg. No./Substance:
0/Receptors, Adrenergic, beta; 51-43-4/Epinephrine; 6539-57-7/Nordefrin

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


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