| Mechanisms of cutaneous vasoconstriction during upright posture. | |
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MedLine Citation:
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PMID: 9055940 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The cutaneous circulation is thought to participate in the neurocirculatory adjustments during orthostatic stress, but the underlying mechanisms mediating such reflex cutaneous vasoconstriction are poorly understood. The aim of this study was to assess the relative importance of baroreceptor (cardiopulmonary and arterial) and positional (vestibular, exercise, veno-arteriolar and myogenic) reflexes in triggering cutaneous vasoconstriction during upright posture. First, hypotensive lower body negative pressure (LBNP) was compared with actual postural changes to assess the relative contributions of baroreceptor reflexes and positional reflexes. Then changes in body position were compared with changes in limb position in the absence or presence of proximal (axillary) or distal (local cutaneous) nerve blocks, to assess the relative contributions of vestibular, exercise, veno-arteriolar and myogenic reflexes. Skin sympathetic nerve activity was determined by microneurography, and skin blood flow was determined by laser Doppler velocimetry. LBNP of -50 mm Hg cardiopulmonary + arterial baroreceptors) had no effect on skin sympathetic nerve activity or skin vascular resistance. In contrast, an upright posture with the arms dependent (baroreceptor + vestibular + exercise + veno-arteriolar reflexes) caused a two- to threefold increase in skin vascular resistance. In the supine position passive movement of the arm into a dependent position to activate veno-arteriolar reflexes alone evoked an increase in skin vascular resistance which approximated the response to normal upright posture. Blocking central sympathetic nerve impulses by application of an axillary blockade did not influence the cutaneous vasoconstrictor response to an upright posture or changes in limb position. In contrast, application of a distal nerve block by local cutaneous surface anaesthesia completely blocked vasoconstrictor responses evoked by these manoeuvres. In conclusion, these experiments in human subjects identify a primary role for veno-arteriolar reflexes in triggering vasoconstriction in the cutaneous circulation during upright posture. |
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Authors:
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S F Vissing; N H Secher; R G Victor |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Acta physiologica Scandinavica Volume: 159 ISSN: 0001-6772 ISO Abbreviation: Acta Physiol. Scand. Publication Date: 1997 Feb |
Date Detail:
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Created Date: 1997-05-23 Completed Date: 1997-05-23 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0370362 Medline TA: Acta Physiol Scand Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 131-8 Citation Subset: IM; S |
Affiliation:
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Copenhagen Muscle Research Centre, Rigshospitaler, University of Copenhagen, Denmark. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Axilla / innervation Baroreflex / physiology Extremities / physiology Female Humans Laser-Doppler Flowmetry Lower Body Negative Pressure Male Nerve Block Posture / physiology* Reflex / physiology Skin / blood supply*, innervation Supine Position Sympathetic Nervous System / physiology Vascular Resistance / physiology Vasoconstriction / physiology* |
| Grant Support | |
ID/Acronym/Agency:
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HL01886/HL/NHLBI NIH HHS; HL06296/HL/NHLBI NIH HHS |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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