| Non-alpha-adrenergic effects on systemic vascular conductance during lower-body negative pressure, static exercise and muscle metaboreflex activation. | |
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MedLine Citation:
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PMID: 22591110 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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AIM: This study tested the hypothesis that non-α-adrenergic mechanisms contribute to systemic vascular conductance (SVC) in a reflex-specific manner during the sympathoexcitatory manoeuvres. METHODS: Twelve healthy subjects underwent lower-body negative pressure (LBNP, -40 mmHg) as well as static handgrip exercise (HG, 20% of maximal force) followed by post-exercise forearm circulatory occlusion (PECO, 5 min each) with and without α-adrenergic blockade induced by phentolamine (PHE). Aortic blood flow, finger blood pressure and superficial femoral artery blood flow were measured to calculate cardiac output, SVC and leg vascular conductance (LVC) during the last minute of each intervention. RESULTS: Mean arterial pressure (MAP) decreased more during LBNP with PHE compared with saline (-7 ± 7 vs. -2 ± 5%, P = 0.016). PHE did not alter the MAP response to HG (+20 ± 12 and +24 ± 16%, respectively, for PHE and saline) but decreased the change in MAP during PECO (+12 ± 7 vs. +21 ± 14%, P = 0.005). The decrease in SVC and LVC with LBNP did not differ between saline and PHE trials (-13 ± 10 vs. -17 ± 10%, respectively, for SVC, P = 0.379). In contrast, the SVC response to HG increased from -9 ± 12 with saline to + 5 ± 15% with PHE (P = 0.002) and from -16 ± 15 with saline to +1 ± 16% with PHE during PECO (P = 0.003). LVC responses to HG or PECO were not different from saline with PHE. CONCLUSIONS: Non-α-adrenergic vasoconstriction was present during LBNP. The systemic vasoconstriction during static exercise and isolated muscle metaboreflex activation, in the absence of leg vasoconstriction, was explained by an α-adrenergic mechanism. Therefore, non-α-adrenergic vasoconstriction is more emphasized during baroreflex, but not metaboreflex-mediated sympathetic activation. |
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Authors:
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A M Kiviniemi; M F Frances; M Rachinsky; R Craen; R J Petrella; H V Huikuri; M P Tulppo; J K Shoemaker |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2012-5-17 |
Journal Detail:
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Title: Acta physiologica (Oxford, England) Volume: - ISSN: 1748-1716 ISO Abbreviation: - Publication Date: 2012 May |
Date Detail:
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Created Date: 2012-5-17 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101262545 Medline TA: Acta Physiol (Oxf) Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Copyright Information:
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© 2012 The Authors Acta Physiologica © 2012 Scandinavian Physiological Society. |
Affiliation:
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School of Kinesiology, The University of Western Ontario, London, ON, Canada; Department of Exercise and Medical Physiology, Verve Research, Oulu, Finland; Institute of Clinical Medicine, The University of Oulu, Oulu, Finland. |
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