title: Dynamic functional cerebral blood volume responses to normobaric hyperoxia in acute ischemic stroke.
abstract: Studies suggest that neuroprotective effects of normobaric oxygen (NBO) therapy in acute stroke are partly mediated by hemodynamic alterations. We investigated cerebral hemodynamic effects of repeated NBO exposures. Serial magnetic resonance imaging (MRI) was performed in Wistar rats subjected to focal ischemic stroke. Normobaric oxygen-induced functional cerebral blood volume (fCBV) responses were analyzed. All rats had diffusion-weighted MRI (DWI) lesions within larger perfusion deficits, with DWI lesion expansion after 3 hours. Functional cerebral blood volume responses to NBO were spatially and temporally heterogeneous. Contralateral healthy tissue responded consistently with vasoconstriction that increased with time. No significant responses were evident in the acute DWI lesion. In hypoperfused regions surrounding the acute DWI lesion, tissue that remained viable until the end of the experiment showed relative preservation of mean fCBV at early time points, with some rats showing increased fCBV (vasodilation); however, these regions later exhibited significantly decreased fCBV (vasoconstriction). Tissue that became DWI abnormal by study-end initially showed marginal fCBV changes that later became moderate fCBV reductions. Our results suggest that a reverse-steal hemodynamic effect may occur in peripheral ischemic zones during NBO treatment of focal stroke. In addition, CBV responses to NBO challenge may have potential as an imaging marker to distinguish ischemic core from salvageable tissues.
authors: Athinoula A Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA.
authors: Ona
authors: O
authors: Wu
authors: Jie
authors: J
authors: Lu
authors: Joseph B
authors: JB
authors: Mandeville
authors: Yoshihiro
authors: Y
authors: Murata
authors: Yasu
authors: Y
authors: Egi
authors: Guangping
authors: G
authors: Dai
authors: John J
authors: JJ
authors: Marota
authors: Izzuddin
authors: I
authors: Diwan
authors: Rick M
authors: RM
authors: Dijkhuizen
authors: Kenneth K
authors: KK
authors: Kwong
authors: Eng H
authors: EH
authors: Lo
authors: Aneesh B
authors: AB
authors: Singhal
mesh_terms: D000818:Animals; D001784:Blood Gas Analysis; D001810:Blood Volume / Q000502:physiology; D002545:Brain Ischemia / Q000188:drug therapy*; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D038524:Diffusion Magnetic Resonance Imaging; D007839:Functional Laterality / Q000502:physiology; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D020768:Middle Cerebral Artery / Q000473:pathology; D010102:Oxygen Inhalation Therapy; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D020521:Stroke / Q000188:drug therapy*