Dynamic Functional Cerebral Blood Volume Responses to Normobaric Hyperoxia in Acute Ischemic Stroke

• Published in: Journal of cerebral blood flow and metabolism 2012-09, Vol.32 (9), p.1800-1809
• Main Authors: Wu, Ona, Lu, Jie, Mandeville, Joseph B, Murata, Yoshihiro, Egi, Yasu, Dai, Guangping, Marota, John J, Diwan, Izzuddin, Dijkhuizen, Rick M, Kwong, Kenneth K, Lo, Eng H, Singhal, Aneesh B
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Blood Gas Analysis; Blood Volume - physiology; Brain Ischemia - drug therapy; Cerebral blood flow; Cerebrovascular Circulation - drug effects; Cerebrovascular Circulation - physiology; Diffusion Magnetic Resonance Imaging; Functional Laterality - physiology; Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy; Hemodynamics; Hemodynamics - drug effects; Hemodynamics - physiology; Hyperoxia; Image Processing, Computer-Assisted; Ischemia; Magnetic Resonance Imaging; Male; Medical sciences; Middle Cerebral Artery - pathology; Nervous system (semeiology, syndromes); Neurology; Neuroprotection; Original; Oxygen Inhalation Therapy; Perfusion; Preservation; Rats; Rats, Wistar; Stroke; Stroke - drug therapy; Vascular diseases and vascular malformations of the nervous system; Vasoconstriction; Vasodilation
• ISSN: 0271-678X; 1559-7016
• DOI: 10.1038/jcbfm.2012.87

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.