| Cerebral vasoreactivity during hypercapnia is reset by augmented sympathetic influence. | |
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MedLine Citation:
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PMID: 21071587 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Sympathetic nerve activity influences cerebral blood flow, but it is unknown whether augmented sympathetic nerve activity resets cerebral vasoreactivity to hypercapnia. This study tested the hypothesis that cerebral vasodilation during hypercapnia is restrained by lower-body negative pressure (LBNP)-stimulated sympathoexcitation. Cerebral hemodynamic responses were assessed in nine healthy volunteers [age 25 yr (SD 3)] during rebreathing-induced increases in partial pressure of end-tidal CO(2) (Pet(CO(2))) at rest and during LBNP. Cerebral hemodynamic responses were determined by changes in flow velocity of middle cerebral artery (MCAV) using transcranial Doppler sonography and in regional cerebral tissue oxygenation (ScO(2)) using near-infrared spectroscopy. Pet(CO(2)) values during rebreathing were similarly increased from 41.9 to 56.5 mmHg at rest and from 40.7 to 56.0 mmHg during LBNP of -15 Torr. However, the rates of increases in MCAV and in ScO(2) per unit increase in Pet(CO(2)) (i.e., the slopes of MCAV/Pet(CO(2)) and ScO(2)/Pet(CO(2))) were significantly (P ≤0.05) decreased from 2.62 ± 0.16 cm·s(-1)·mmHg(-1) and 0.89 ± 0.10%/mmHg at rest to 1.68 ± 0.18 cm·s(-1)·mmHg(-1) and 0.63 ± 0.07%/mmHg during LBNP. In conclusion, the sensitivity of cerebral vasoreactivity to hypercapnia, in terms of the rate of increases in MCAV and in ScO(2), is diminished by LBNP-stimulated sympathoexcitation. |
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Authors:
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Peizhen Zhang; Guoyuan Huang; Xiangrong Shi |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural Date: 2010-11-11 |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: 110 ISSN: 1522-1601 ISO Abbreviation: J. Appl. Physiol. Publication Date: 2011 Feb |
Date Detail:
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Created Date: 2011-02-09 Completed Date: 2011-06-07 Revised Date: 2012-02-01 |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: United States |
Other Details:
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Languages: eng Pagination: 352-8 Citation Subset: IM |
Affiliation:
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Department of Integrative Physiology, UNT Health Science Center, Fort Worth, TX 76107, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Baroreflex* Blood Flow Velocity Cerebral Arteries / innervation, physiopathology* Cerebrovascular Circulation* Female Humans Hypercapnia / physiopathology* Male Sympathetic Nervous System / physiopathology* Vasomotor System / physiopathology* |
| Grant Support | |
ID/Acronym/Agency:
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R01-HL-65613/HL/NHLBI NIH HHS |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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