The Effect of Basal Vasodilation on Hypercapnic and Hypocapnic Reactivity Measured using Magnetic Resonance Imaging
Open Access
- 20 October 2010
- journal article
- research article
- Published by SAGE Publications in Journal of Cerebral Blood Flow & Metabolism
- Vol. 31 (2), 426-438
- https://doi.org/10.1038/jcbfm.2010.187
Abstract
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% CO2. 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.Keywords
This publication has 52 references indexed in Scilit:
- Absolute Arterial Cerebral Blood Volume Quantification Using Inflow Vascular-Space-Occupancy with Dynamic Subtraction Magnetic Resonance ImagingJournal of Cerebral Blood Flow & Metabolism, 2010
- Characterization of regional heterogeneity in cerebrovascular reactivity dynamics using novel hypocapnia task and BOLD fMRINeuroImage, 2009
- Vascular space occupancy (VASO) cerebral blood volume‐weighted MRI identifies hemodynamic impairment in patients with carotid artery diseaseJournal of Magnetic Resonance Imaging, 2009
- Vasoreactivity and peri-infarct hyperintensities in strokeNeurology, 2009
- Mapping and correction of vascular hemodynamic latency in the BOLD signalNeuroImage, 2008
- The respiration response function: The temporal dynamics of fMRI signal fluctuations related to changes in respirationNeuroImage, 2008
- The Influence of Moderate Hypercapnia on Neural Activity in the Anesthetized Nonhuman PrimateCerebral Cortex, 2008
- Controlled inspiration depth reduces variance in breath-holding-induced BOLD signalNeuroImage, 2008
- A calibration method for quantitative BOLD fMRI based on hyperoxiaNeuroImage, 2007
- Assignment of functional activations to probabilistic cytoarchitectonic areas revisitedNeuroImage, 2007