Abstract
Isoflurane is a well-known volatile anesthetic. However, it remains equivocal whether its effects on BOLD signal differ depending on the types of intracranial structures, such as capillaries and large blood vessels. We compared dose-dependent effect of isoflurane on the basal BOLD signals in distinct cerebral structures (tissue structure or large vessels) using high resolution T2*-images at 9.4 T MRI system in rat somatosensory cortex. The local field potential (LFP) in the somatosensory cortex and mean arterial pressure (MAP) were also investigated. Isoflurane induced inverted U-shaped dose-dependent change in BOLD signal in large vessels and tissue regions: BOLD signal under 2.0% and 2.5% isoflurane significantly increased from the maintenance dose (1.5%) and that under 3.0% was similar to maintenance dose. Remarkably, BOLD signal increase in tissue regions under 2.5% was significantly smaller than that in large vessels. The MAP decreased monotonically due to the dose of isoflurane and the LFP was strongly suppressed under high dose (2.5% and 3.0%). These results indicate that isoflurane-induced alteration of MAP and neuronal activity affected BOLD signal and, especially, BOLD signal in the tissue regions was more affected by the neuronal activity.
Highlights
The commonly used functional MRI method is the blood oxygenation level-dependent (BOLD) contrast[1]
Long-lasting isoflurane anesthesia results in negative BOLD responses in rat cortex[10]. Those results indicate that the interpretation of the functional MRI (fMRI) data collected in the presence of the anesthetics should be made with care especially in the cases where the basal BOLD signal is already elevated due to the vasodilation by the drugs[9,11]
To establish basis to understand such potential effects, we investigated the dose-dependent effect of isoflurane on the basal BOLD signals separately in tissue regions and large vascular structures in rat somatosensory cortex by means of high resolution imaging at ultra-high magnetic field (UHF) MRI system
Summary
The commonly used functional MRI (fMRI) method is the blood oxygenation level-dependent (BOLD) contrast[1]. To establish basis to understand such potential effects, we investigated the dose-dependent effect of isoflurane on the basal BOLD signals separately in tissue regions (including capillary) and large vascular structures (including artery and vein) in rat somatosensory cortex by means of high resolution imaging at UHF MRI system. We compared these basal BOLD changes with neuronal activity (local field potential, LFP) and mean arterial pressure (MAP)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
