Document Detail


Cardiovascular function in the heat-stressed human.
MedLine Citation:
PMID:  20345414     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Heat stress, whether passive (i.e. exposure to elevated environmental temperatures) or via exercise, results in pronounced cardiovascular adjustments that are necessary for adequate temperature regulation as well as perfusion of the exercising muscle, heart and brain. The available data suggest that generally during passive heat stress baroreflex control of heart rate and sympathetic nerve activity are unchanged, while baroreflex control of systemic vascular resistance may be impaired perhaps due to attenuated vasoconstrictor responsiveness of the cutaneous circulation. Heat stress improves left ventricular systolic function, evidenced by increased cardiac contractility, thereby maintaining stroke volume despite large reductions in ventricular filling pressures. Heat stress-induced reductions in cerebral perfusion likely contribute to the recognized effect of this thermal condition in reducing orthostatic tolerance, although the mechanism(s) by which this occurs is not completely understood. The combination of intense whole-body exercise and environmental heat stress or dehydration-induced hyperthermia results in significant cardiovascular strain prior to exhaustion, which is characterized by reductions in cardiac output, stroke volume, arterial pressure and blood flow to the brain, skin and exercising muscle. These alterations in cardiovascular function and regulation late in heat stress/dehydration exercise might involve the interplay of both local and central reflexes, the contribution of which is presently unresolved.
Authors:
C G Crandall; J González-Alonso
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Review     Date:  2010-03-24
Journal Detail:
Title:  Acta physiologica (Oxford, England)     Volume:  199     ISSN:  1748-1716     ISO Abbreviation:  Acta Physiol (Oxf)     Publication Date:  2010 Aug 
Date Detail:
Created Date:  2010-07-19     Completed Date:  2010-10-25     Revised Date:  2013-03-27    
Medline Journal Info:
Nlm Unique ID:  101262545     Medline TA:  Acta Physiol (Oxf)     Country:  England    
Other Details:
Languages:  eng     Pagination:  407-23     Citation Subset:  IM    
Affiliation:
Department of Internal Medicine Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, and University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75231, USA. craigcrandall@texashealth.org
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MeSH Terms
Descriptor/Qualifier:
Baroreflex / physiology
Body Temperature / physiology
Cardiovascular Physiological Phenomena*
Cerebrovascular Circulation
Exercise / physiology
Extremities / anatomy & histology
Heat Stress Disorders / physiopathology*
Hemodynamics / physiology*
Humans
Muscle, Skeletal / blood supply
Regional Blood Flow / physiology
Skin / blood supply
Grant Support
ID/Acronym/Agency:
HL61388/HL/NHLBI NIH HHS; HL84072/HL/NHLBI NIH HHS; R01 HL061388/HL/NHLBI NIH HHS; R01 HL084072/HL/NHLBI NIH HHS
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