title: Neurovascular coupling varies with level of global cerebral ischemia in a rat model.
abstract: In this study, cerebral blood flow, oxygenation, metabolic, and electrical functional responses to forepaw stimulation were monitored in rats at different levels of global cerebral ischemia from mild to severe. Laser speckle contrast imaging and optical imaging of intrinsic signals were used to measure changes in blood flow and oxygenation, respectively, along with a compartmental model to calculate changes in oxygen metabolism from these measured changes. To characterize the electrical response to functional stimulation, we measured somatosensory evoked potentials (SEPs). Global graded ischemia was induced through unilateral carotid artery occlusion, bilateral carotid artery occlusion, bilateral carotid and right subclavian artery (SCA) occlusion, or carotid and SCA occlusion with negative lower body pressure. We found that the amplitude of the functional metabolic response remained tightly coupled to the amplitude of the SEP at all levels of ischemia observed. However, as the level of ischemia became more severe, the flow response was more strongly attenuated than the electrical response, suggesting that global ischemia was associated with an uncoupling between the functional flow and electrical responses.
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA. wbaker@sas.upenn.edu
authors.forename: Wesley B
authors.initials: WB
authors.lastname: Baker
authors.forename: Zhenghui
authors.initials: Z
authors.lastname: Sun
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Hiraki
authors.forename: Mary E
authors.initials: ME
authors.lastname: Putt
authors.forename: Turgut
authors.initials: T
authors.lastname: Durduran
authors.forename: Martin
authors.initials: M
authors.lastname: Reivich
authors.forename: Arjun G
authors.initials: AG
authors.lastname: Yodh
authors.forename: Joel H
authors.initials: JH
authors.lastname: Greenberg
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism* / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004195:Disease Models, Animal; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005552:Forelimb / Q000294:innervation / Q000502:physiology; D008297:Male; D061848:Optical Imaging; D010101:Oxygen Consumption / Q000502:physiology*; D010812:Physical Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012720:Severity of Illness Index