| Hemodynamic responses to heat stress in the resting and exercising human leg: insight into the effect of temperature on skeletal muscle blood flow. | |
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MedLine Citation:
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PMID: 21178127 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Heat stress increases limb blood flow and cardiac output (Q) in humans, presumably in sole response to an augmented thermoregulatory demand of the skin circulation. Here we tested the hypothesis that local hyperthermia also increases skeletal muscle blood flow at rest and during exercise. Hemodynamics, blood and tissue oxygenation, and muscle, skin, and core temperatures were measured at rest and during exercise in 11 males across four conditions of progressive whole body heat stress and at rest during isolated leg heat stress. During whole body heat stress, leg blood flow (LBF), Q, and leg (LVC) and systemic vascular conductance increased gradually with elevations in muscle temperature both at rest and during exercise (r(2) = 0.86-0.99; P < 0.05). Enhanced LBF and LVC were accompanied by reductions in leg arteriovenous oxygen (a-vO(2)) difference and increases in deep femoral venous O(2) content and quadriceps tissue oxygenation, reflecting elevations in muscle and skin perfusion. The increase in LVC occurred despite an augmented plasma norepinephrine (P < 0.05) and was associated with elevations in muscle temperature (r(2) = 0.85; P = 0.001) and arterial plasma ATP (r(2) = 0.87; P < 0.001). Isolated leg heat stress accounted for one-half of the increase in LBF with severe whole body heat stress. Our findings suggest that local hyperthermia also induces vasodilatation of the skeletal muscle microvasculature, thereby contributing to heat stress and exercise hyperemia. The increased limb muscle vasodilatation in these conditions of elevated muscle sympathetic vasoconstrictor activity is closely related to the rise in arterial plasma ATP and local tissue temperature. |
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Authors:
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James Pearson; David A Low; Eric Stöhr; Kameljit Kalsi; Leena Ali; Horace Barker; José González-Alonso |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2010-12-22 |
Journal Detail:
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Title: American journal of physiology. Regulatory, integrative and comparative physiology Volume: 300 ISSN: 1522-1490 ISO Abbreviation: Am. J. Physiol. Regul. Integr. Comp. Physiol. Publication Date: 2011 Mar |
Date Detail:
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Created Date: 2011-03-07 Completed Date: 2011-05-09 Revised Date: 2011-07-27 |
Medline Journal Info:
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Nlm Unique ID: 100901230 Medline TA: Am J Physiol Regul Integr Comp Physiol Country: United States |
Other Details:
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Languages: eng Pagination: R663-73 Citation Subset: IM |
Affiliation:
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Centre for Sports Medicine and Human Performance, Brunel University West London, Uxbridge, Middlesex, UK. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adenosine Triphosphate
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blood Biological Markers / blood Blood Flow Velocity Body Temperature Regulation Epinephrine / blood Exercise* Heat Stress Disorders / blood, physiopathology* Hemodynamics* Humans Lower Extremity Male Microcirculation Muscle Contraction* Muscle, Skeletal / blood supply* Norepinephrine / blood Oxygen Consumption Regional Blood Flow Rest* Skin Temperature Time Factors Vasodilation Water-Electrolyte Balance Young Adult |
| Chemical | |
Reg. No./Substance:
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0/Biological Markers; 51-41-2/Norepinephrine; 51-43-4/Epinephrine; 56-65-5/Adenosine Triphosphate |
| Comments/Corrections | |
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