Document Detail


Heat stress attenuates the increase in arterial blood pressure during the cold pressor test.
MedLine Citation:
PMID:  20798269     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The mechanisms by which heat stress impairs the control of blood pressure leading to compromised orthostatic tolerance are not thoroughly understood. A possible mechanism may be an attenuated blood pressure response to a given increase in sympathetic activity. This study tested the hypothesis that whole body heating attenuates the blood pressure response to a non-baroreflex-mediated sympathoexcitatory stimulus. Ten healthy subjects were instrumented for the measurement of integrated muscle sympathetic nerve activity (MSNA), mean arterial blood pressure (MAP), heart rate, sweat rate, and forearm skin blood flow. Subjects were exposed to a cold pressor test (CPT) by immersing a hand in an ice water slurry for 3 min while otherwise normothermic and while heat stressed (i.e., increase core temperature ~0.7°C via water-perfused suit). Mean responses from the final minute of the CPT were evaluated. In both thermal conditions CPT induced significant increases in MSNA and MAP without altering heart rate. Although the increase in MSNA to the CPT was similar between thermal conditions (normothermia: Δ14.0 ± 2.6; heat stress: Δ19.1 ± 2.6 bursts/min; P = 0.09), the accompanying increase in MAP was attenuated when subjects were heat stressed (normothermia: Δ25.6 ± 2.3, heat stress: Δ13.4 ± 3.0 mmHg; P < 0.001). The results demonstrate that heat stress can attenuate the pressor response to a sympathoexcitatory stimulus.
Authors:
Jian Cui; Manabu Shibasaki; David A Low; David M Keller; Scott L Davis; Craig G Crandall
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2010-08-26
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  109     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-11-09     Completed Date:  2011-02-18     Revised Date:  2011-11-01    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1354-9     Citation Subset:  IM    
Affiliation:
Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, TX 75231, USA.
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MeSH Terms
Descriptor/Qualifier:
Adult
Arteries / physiopathology
Blood Flow Velocity
Blood Pressure*
Cold Temperature*
Female
Forearm
Heart Rate
Heat Stress Disorders / physiopathology*
Humans
Male
Muscle, Skeletal / innervation
Regional Blood Flow
Respiratory Mechanics
Skin / blood supply*
Sweating
Sympathetic Nervous System / physiopathology
Time Factors
Vascular Resistance
Vasoconstriction*
Grant Support
ID/Acronym/Agency:
HL-61388/HL/NHLBI NIH HHS; HL-84072/HL/NHLBI NIH HHS

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


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