| Progressive muscle metaboreflex activation gradually decreases spontaneous heart rate baroreflex sensitivity during dynamic exercise. | |
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MedLine Citation:
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PMID: 19966049 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Ischemia of active skeletal muscle elicits a pressor response termed the muscle metaboreflex. We tested the hypothesis that in normal dogs during dynamic exercise, graded muscle metaboreflex activation (MMA) would progressively attenuate spontaneous heart rate baroreflex sensitivity (SBRS). The animals were chronically instrumented to measure heart rate (HR), cardiac output (CO), mean and systolic arterial pressure (MAP and SAP), and left ventricular systolic pressures (LVSP) at rest and during mild or moderate treadmill exercise before and during progressive MMA [via graded reductions of hindlimb blood flow (HLBF)]. SBRS [slopes of the linear relationships (LRs) between HR and LVSP or SAP during spontaneous sequences of > or =3 consecutive beats when HR changed inversely vs. pressure] decreased during mild exercise from the resting values (-5.56 +/- 0.86 vs. -2.67 +/- 0.50 beats.min(-1).mmHg(-1), P <0.05), and in addition, these LRs were shifted upward. Progressive MMA gradually and linearly increased MAP, CO, and HR; linearly decreased SBRS; and shifted LRs upward and rightward to higher HR and pressures denoting baroreflex resetting. Moderate exercise caused a substantial reduction in SBRS (-1.57 +/- 0.38 beats.min(-1).mmHg(-1), P <0.05) and both an upward and rightward resetting. Gradual MMA at this higher workload also caused significant progressive increases in MAP, CO, and HR and progressive decreases in SBRS, and the LRs were shifted to higher MAP and HR. Our results demonstrate that gradual MMA during mild and moderate dynamic exercise progressively decreases SBRS. In addition, baroreflex control of HR is progressively reset to higher blood pressure and HR in proportion to the extent of MMA. |
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Authors:
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Javier A Sala-Mercado; Masashi Ichinose; Matthew Coutsos; Zhenhua Li; Dominic Fano; Tomoko Ichinose; Elizabeth J Dawe; Donal S O'Leary |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural Date: 2009-12-04 |
Journal Detail:
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Title: American journal of physiology. Heart and circulatory physiology Volume: 298 ISSN: 1522-1539 ISO Abbreviation: Am. J. Physiol. Heart Circ. Physiol. Publication Date: 2010 Feb |
Date Detail:
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Created Date: 2010-01-21 Completed Date: 2010-02-16 Revised Date: 2011-07-22 |
Medline Journal Info:
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Nlm Unique ID: 100901228 Medline TA: Am J Physiol Heart Circ Physiol Country: United States |
Other Details:
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Languages: eng Pagination: H594-600 Citation Subset: IM |
Affiliation:
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Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Autonomic Nervous System / physiology Baroreflex / physiology* Blood Pressure / physiology Cardiac Output / physiology Dogs Feedback, Physiological / physiology Female Heart Rate / physiology* Male Models, Animal Muscle, Skeletal / metabolism* Physical Conditioning, Animal / physiology* Reflex / physiology* Ventricular Function, Left / physiology |
| Grant Support | |
ID/Acronym/Agency:
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HL-55473/HL/NHLBI NIH HHS |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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