| The effect of basal vasodilation on hypercapnic and hypocapnic reactivity measured using magnetic resonance imaging. | |
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MedLine Citation:
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PMID: 20959855 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Cerebrovascular reactivity to vasodilatory hypercapnic and vasoconstrictive hypocapnic challenges is known to be altered in several hemodynamic disorders, which is often attributable to changes in smooth muscle-mediated vascular compliance. Recently, attenuated reactivity to hypercapnia but enhanced reactivity to hypocapnia was observed in patients with chronic stroke. We hypothesize that the latter observation could be explained by a change in the basal vascular tone. In particular, reduced cerebral perfusion pressure, as is prevalent in these patients, may cause vasodilation through autoregulatory mechanisms, and this compensatory baseline condition may alter reactivity to vasoconstrictive hypocapnic challenges. To test this hypothesis, a predilated vascular condition was created in young, healthy subjects (n=11; age=23 to 36 years) using inhalation of 4% CO(2). Using blood oxygenation level-dependent functional magnetic resonance imaging at 3 T, breath holding and cued deep breathing respiratory challenges were administered to assess hypercapnia and hypocapnia reactivity, respectively. During the predilated condition, vasoconstrictive reactivity to hypocapnia was significantly (21.1%, P=0.016) enhanced throughout the gray matter, whereas there was no significant change (6.4%, P=0.459) in hypercapnic vasodilatory reactivity. This suggests that baseline vasodilation may explain the enhanced hypocapnia reactivity observed in some stroke patients, and that hypocapnia challenges may help identify the level of vascular compliance in patients with reduced cerebral perfusion pressure. |
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Authors:
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Molly G Bright; Manus J Donahue; Jeff H Duyn; Peter Jezzard; Daniel P Bulte |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Intramural; Research Support, Non-U.S. Gov't Date: 2010-10-20 |
Journal Detail:
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Title: Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism Volume: 31 ISSN: 1559-7016 ISO Abbreviation: J. Cereb. Blood Flow Metab. Publication Date: 2011 Feb |
Date Detail:
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Created Date: 2011-02-04 Completed Date: 2011-03-17 Revised Date: 2012-02-01 |
Medline Journal Info:
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Nlm Unique ID: 8112566 Medline TA: J Cereb Blood Flow Metab Country: United States |
Other Details:
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Languages: eng Pagination: 426-38 Citation Subset: IM |
Affiliation:
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Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA. mbright@fmrib.ox.ac.uk |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Administration, Inhalation Adult Carbon Dioxide / metabolism, pharmacology Cerebrovascular Circulation / physiology Echo-Planar Imaging Female Hemodynamics / physiology Humans Hypercapnia / physiopathology* Hypocapnia / physiopathology* Linear Models Magnetic Resonance Imaging Male Oxygen / blood Respiratory Mechanics / physiology Vasodilation / physiology* Young Adult |
| Grant Support | |
ID/Acronym/Agency:
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//Medical Research Council |
| Chemical | |
Reg. No./Substance:
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124-38-9/Carbon Dioxide; 7782-44-7/Oxygen |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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