| Determinants of human cerebral pressure-flow velocity relationships: new insights from vascular modelling and Ca²⁺ channel blockade. | |
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MedLine Citation:
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PMID: 21540346 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The fundamental determinants of human dynamic cerebral autoregulation are poorly understood, particularly the role of vascular compliance and the myogenic response. We sought to 1) determine whether capacitive blood flow associated with vascular compliance and driven by the rate of change in mean arterial blood pressure (dMAP/dt) is an important determinant of middle cerebral artery velocity (MCAv) dynamics and 2) characterise the impact of myogenic blockade on these cerebral pressure-flow velocity relations in humans. We measured MCAv and mean arterial pressure (MAP) during oscillatory lower body negative pressure (n =8) at 0.10 and 0.05 Hz before and after cerebral Ca²⁺ channel blockade (nimodipine). Pressure-flow velocity relationships were characterised using transfer function analysis and a regression-based Windkessel analysis that incorporates MAP and dMAP/dt as predictors of MCAv dynamics. Results show that incorporation of dMAP/dt accounted for more MCAv variance (R² 0.80-0.99) than if only MAP was considered (R2 0.05-0.90). The capacitive gain relating dMAP/dt and MCAv was strongly correlated to transfer function gain (0.05 Hz, r =0.93, P<0.01; 0.10 Hz, r =0.91, P<0.01), but not to phase or coherence. Ca²⁺ channel blockade increased the conductive gain relation between MAP and MCAv (P<0.05), and reduced phase at 0.05 Hz (P<0.01). Capacitive and transfer function gain were unaltered. The findings suggest capacitive blood flow is an important determinant of cerebral haemodynamics that bears strong relations to some metrics of dynamic cerebral autoregulation derived from transfer function analysis, and that Ca²⁺ channel blockade enhances pressure-driven resistive blood flow but does not alter capacitive blood flow. the causes and effects of cerebrovascular diseases such as stroke and dementia. |
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Authors:
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Yu-Chieh Tzeng; Gregory S H Chan; Christopher K Willie; Philip N Ainslie |
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Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't Date: 2011-05-03 |
Journal Detail:
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Title: The Journal of physiology Volume: 589 ISSN: 1469-7793 ISO Abbreviation: J. Physiol. (Lond.) Publication Date: 2011 Jul |
Date Detail:
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Created Date: 2011-07-04 Completed Date: 2012-04-13 Revised Date: 2012-07-02 |
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: 3263-74 Citation Subset: IM |
Affiliation:
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Cardiovascular Systems Laboratory, Department of Surgery and Anaesthesia, University of Otago, Wellington, 23A Mein Street, PO Box 7343, Wellington South, New Zealand. shieak.tzeng@otago.ac.nz |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Blood Flow Velocity / drug effects, physiology Blood Pressure / drug effects, physiology* Calcium Channel Blockers / pharmacology* Calcium Signaling / drug effects, physiology* Cerebrovascular Circulation / drug effects, physiology* Compliance / drug effects, physiology Electrocardiography / drug effects, methods Humans Male Middle Cerebral Artery / drug effects, physiology Models, Molecular Nimodipine / pharmacology Respiration / drug effects Young Adult |
| Chemical | |
Reg. No./Substance:
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0/Calcium Channel Blockers; 66085-59-4/Nimodipine |
| Comments/Corrections | |
Comment In:
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J Physiol. 2011 Jul 1;589(Pt 13):3051-2
[PMID:
21724582
]
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Erratum In:
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J Physiol. 2011 Aug 15;589(Pt 16):4077 |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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