The interaction of carbon dioxide and hypoxia in the control of cerebral blood flow

Both hypoxia and carbon dioxide increase cerebral blood flow (CBF), and their effective interaction is currently thought to be additive. Our objective was to test this hypothesis. Eight healthy subjects breathed a series of progressively hypoxic gases at three levels of carbon dioxide. Middle cerebr...

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Bibliographic Details
Published in:Pflügers Archiv 2012-10, Vol.464 (4), p.345-351
Main Authors: Mardimae, Alexandra, Balaban, Dahlia Y., Machina, Matthew A., Han, Jay S., Katznelson, Rita, Minkovich, Leonid L., Fedorko, Ludwik, Murphy, Patricia M., Wasowicz, Marcin, Naughton, Finola, Meineri, Massimiliano, Fisher, Joseph A., Duffin, James
Format: Article
Language:English
Subjects:
Adult
Analysis of variance
Arteries
Biomedical and Life Sciences
Biomedicine
Blood
Blood flow
Blood Flow Velocity - physiology
Blood Gas Analysis
Brain
Carbon dioxide
Carbon Dioxide - blood
Carbon Dioxide - physiology
Cell Biology
Cerebrovascular Circulation - physiology
Female
Human Physiology
Humans
Hypoxia
Hypoxia - blood
Hypoxia - physiopathology
Inhalation
Integrative Physiology
Male
Middle Aged
Middle Cerebral Artery - physiology
Molecular Medicine
Neurosciences
Oxygen - blood
Oxygen - physiology
Receptors
Regional Blood Flow - physiology
Regression
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Summary:Both hypoxia and carbon dioxide increase cerebral blood flow (CBF), and their effective interaction is currently thought to be additive. Our objective was to test this hypothesis. Eight healthy subjects breathed a series of progressively hypoxic gases at three levels of carbon dioxide. Middle cerebral artery velocity, as an index of CBF; partial pressures of carbon dioxide and oxygen and concentration of oxygen in arterial blood; and mean arterial blood pressure were monitored. The product of middle cerebral artery velocity and arterial concentration of oxygen was used as an index of cerebral oxygen delivery. Two-way repeated measures analyses of variance (rmANOVA) found a significant interaction of carbon dioxide and hypoxia factors for both CBF and cerebral oxygen delivery. Regression models using sigmoidal dependence on carbon dioxide and a rectangular hyperbolic dependence on hypoxia were fitted to the data to illustrate this interaction. We concluded that carbon dioxide and hypoxia act synergistically in their control of CBF so that the delivery of oxygen to the brain is enhanced during hypoxic hypercapnia and, although reduced during normoxic hypocapnia, can be restored to normal levels with progressive hypoxia.
ISSN:0031-6768
1432-2013
DOI:10.1007/s00424-012-1148-1