Document Detail


Blacks and whites differ in responses, but not tolerance, to orthostatic stress.
MedLine Citation:
PMID:  15045596     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This study tested the hypothesis that normotensive black males differ from white males in their autonomic and cardiovascular responses to severe orthostatic stress. College age men (9 blacks, 9 whites) underwent graded lower body negative pressure (LBNP; 10 mmHg steps of 6 min each) to either -100 mmHg or presyncope. LBNP tolerance between the two groups did not differ (LBNP tolerance index: 378 +/- 34 vs 404 +/- 1 9mmHg.min, blacks vs whites). Responses to LBNP common to all subjects (< or = -40 mmHg), including spontaneous baroreflex sensitivity (sequence technique), did not differ between groups except whites experienced an earlier and more pronounced decline in total peripheral conductance than blacks (P < 0.01). At test termination, the heart rate variability measure of low frequency/high frequency ratio increased more in blacks than whites (5.2 +/- 1.1 vs 2.7 +/- 0.7 units; P < 0.05) while cardiac output and total peripheral conductance were lower in whites (both P < 0.05). These data suggest that blacks and whites have similar LBNP tolerances. They maintain blood pressure equally well when exposed to graded LBNP to presyncope, yet they differ in their mechanisms for doing so.
Authors:
Warren D Franke; Kichang Lee; Dwayne B Buchanan; Juliane P Hernandez
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Clinical autonomic research : official journal of the Clinical Autonomic Research Society     Volume:  14     ISSN:  0959-9851     ISO Abbreviation:  Clin. Auton. Res.     Publication Date:  2004 Feb 
Date Detail:
Created Date:  2004-03-26     Completed Date:  2004-10-19     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  9106549     Medline TA:  Clin Auton Res     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  19-25     Citation Subset:  IM    
Affiliation:
247 Forker Building, Dept. of Health and Human Performance, Iowa State University, Ames, IA 50011, USA. wfranke@iastate.edu
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Physiological*
Adult
African Continental Ancestry Group*
Baroreflex
Cardiac Output
Cardiovascular System / physiopathology*
European Continental Ancestry Group*
Heart Rate
Humans
Hypotension, Orthostatic / ethnology,  etiology,  physiopathology*
Lower Body Negative Pressure*
Male
Vascular Resistance

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


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