TY - JOUR
T1 - Imaging oxygen consumption in forepaw somatosensory stimulation in rats under isoflurane anesthesia
AU - Liu, Zhaohui M.
AU - Schmidt, Karl F.
AU - Sicard, Kenneth M.
AU - Duong, Timothy Q.
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2004/8
Y1 - 2004/8
N2 - The cerebral metabolic rate of oxygen (CMRO2) was dynamically evaluated on a pixel-by-pixel basis in isoflurane-anesthetized and spontaneously breathing rats following graded electrical somatosensory forepaw stimulations (4, 6, and 8mA). In contrast to α-chloralose, which is the most widely used anesthetic in forepaw-stimulation fMRI studies of rats under mechanical ventilation, isoflurane (1.1-1.2%) provided a stable anesthesia level over a prolonged period, without the need to adjust the ventilation volume/rate or sample blood gases. Combined cerebral blood flow signals (CBF) and blood oxygenation level-dependent (BOLD) fMRI signals were simultaneously measured with the use of a multislice continuous arterial spin labeling (CASL) technique (two-coil setup). CMRO2 was calculated using the biophysical BOLD model of Ogawa et al. (Proc Natl Acad Sci USA 1992;89:5951-5955). The stimulus-evoked BOLD percent changes at 4, 6, and 8mA were, respectively, 0.5% ± 0.2%, 1.4% ± 0.3%, and 2.0% ± 0.3% (mean ± SD, N = 6). The CBF percent changes were 23% ± 6%, 58% ± 9%, and 87% ± 14%. The CMRO2 percent changes were 14% ± 4%, 24% ± 6%, and 43% ± 11%. BOLD, CBF, and CMRO2 activations were localized to the forepaw somatosensory cortices without evidence of plateau for oxygen consumption, indicative of partial coupling of CBF and CMRO 2. This study describes a useful forepaw-stimulation model for fMRI, and demonstrate that CMRO2 changes can be dynamically imaged on a pixel-by-pixel basis in a single setting with high spatiotemporal resolution.
AB - The cerebral metabolic rate of oxygen (CMRO2) was dynamically evaluated on a pixel-by-pixel basis in isoflurane-anesthetized and spontaneously breathing rats following graded electrical somatosensory forepaw stimulations (4, 6, and 8mA). In contrast to α-chloralose, which is the most widely used anesthetic in forepaw-stimulation fMRI studies of rats under mechanical ventilation, isoflurane (1.1-1.2%) provided a stable anesthesia level over a prolonged period, without the need to adjust the ventilation volume/rate or sample blood gases. Combined cerebral blood flow signals (CBF) and blood oxygenation level-dependent (BOLD) fMRI signals were simultaneously measured with the use of a multislice continuous arterial spin labeling (CASL) technique (two-coil setup). CMRO2 was calculated using the biophysical BOLD model of Ogawa et al. (Proc Natl Acad Sci USA 1992;89:5951-5955). The stimulus-evoked BOLD percent changes at 4, 6, and 8mA were, respectively, 0.5% ± 0.2%, 1.4% ± 0.3%, and 2.0% ± 0.3% (mean ± SD, N = 6). The CBF percent changes were 23% ± 6%, 58% ± 9%, and 87% ± 14%. The CMRO2 percent changes were 14% ± 4%, 24% ± 6%, and 43% ± 11%. BOLD, CBF, and CMRO2 activations were localized to the forepaw somatosensory cortices without evidence of plateau for oxygen consumption, indicative of partial coupling of CBF and CMRO 2. This study describes a useful forepaw-stimulation model for fMRI, and demonstrate that CMRO2 changes can be dynamically imaged on a pixel-by-pixel basis in a single setting with high spatiotemporal resolution.
KW - Arterial spin labeling
KW - BOLD
KW - CBF
KW - Cerebral metabolic rate of oxygen
KW - CMR
KW - fMRI
KW - Lactate
KW - Oxidative metabolism
KW - Perfusion
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U2 - 10.1002/mrm.20148
DO - 10.1002/mrm.20148
M3 - Article
C2 - 15282809
AN - SCOPUS:3543130199
VL - 52
SP - 277
EP - 285
JO - Magnetic Resonance in Medicine
JF - Magnetic Resonance in Medicine
SN - 0740-3194
IS - 2
ER -