| Interaction between the ventilatory and cerebrovascular responses to hypo- and hypercapnia at rest and during exercise. | |
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MedLine Citation:
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PMID: 18635644 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Cerebrovascular reactivity to changes in the partial pressure of arterial carbon dioxide (P(a,CO(2))) via limiting changes in brain [H(+)] modulates ventilatory control. It remains unclear, however, how exercise-induced alterations in respiratory chemoreflex might influence cerebral blood flow (CBF), in particular the cerebrovascular reactivity to CO(2). The respiratory chemoreflex system controlling ventilation consists of two subsystems: the central controller (controlling element), and peripheral plant (controlled element). In order to examine the effect of exercise-induced alterations in ventilatory chemoreflex on cerebrovascular CO(2) reactivity, these two subsystems of the respiratory chemoreflex system and cerebral CO(2) reactivity were evaluated (n = 7) by the administration of CO(2) as well as by voluntary hypo- and hyperventilation at rest and during steady-state exercise. During exercise, in the central controller, the regression line for the P(a,CO(2))-minute ventilation (VE) relation shifted to higher VE and P(a,CO(2)) with no change in gain (P = 0.84). The functional curve of the peripheral plant also reset rightward and upward during exercise. However, from rest to exercise, gain of the peripheral plant decreased, especially during the hypercapnic condition (-4.1 +/- 0.8 to -2.0 +/- 0.2 mmHg l(-1) min(-1), P = 0.01). Therefore, under hypercapnia, total respiratory loop gain was markedly reduced during exercise (-8.0 +/- 2.3 to -3.5 +/- 1.0 U, P = 0.02). In contrast, cerebrovascular CO(2) reactivity at each condition, especially to hypercapnia, was increased during exercise (2.4 +/- 0.2 to 2.8 +/- 0.2% mmHg(-1), P = 0.03). These findings indicate that, despite an attenuated chemoreflex system controlling ventilation, elevations in cerebrovascular reactivity might help maintain CO(2) homeostasis in the brain during exercise. |
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Authors:
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Shigehiko Ogoh; Naoyuki Hayashi; Masashi Inagaki; Philip N Ainslie; Tadayoshi Miyamoto |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2008-07-17 |
Journal Detail:
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Title: The Journal of physiology Volume: 586 ISSN: 1469-7793 ISO Abbreviation: J. Physiol. (Lond.) Publication Date: 2008 Sep |
Date Detail:
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Created Date: 2008-09-03 Completed Date: 2008-12-18 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 0266262 Medline TA: J Physiol Country: England |
Other Details:
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Languages: eng Pagination: 4327-38 Citation Subset: IM |
Affiliation:
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Department of Integrative Physiology, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA. sogoh@hsc.unt.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Brain
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blood supply* Exercise / physiology* Humans Hypercapnia / metabolism* Hypocapnia Male Oxygen / metabolism Young Adult |
| Chemical | |
Reg. No./Substance:
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7782-44-7/Oxygen |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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