Microvascular Oxygen Tension and Flow Measurements in Rodent Cerebral Cortex during Baseline Conditions and Functional Activation

Journal of Cerebral Blood Flow and Metabolism - Tập 31 Số 4 - Trang 1051-1063 - 2011
Mohammad A. Yaseen1, Vivek J. Srinivasan1, Sava Sakadžić1, Harsha Radhakrishnan1, Iwona Gorczyńska2, Wei‐Cheng Wu1, James G. Fujimoto2, David A. Boas1
1Department of Radiology, MGH/MIT/HMS Athinuola A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
2Department of Electrical Engineering and Computer Science, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA

Tóm tắt

Measuring cerebral oxygen delivery and metabolism microscopically is important for interpreting macroscopic functional magnetic resonance imaging (fMRI) data and identifying pathological changes associated with stroke, Alzheimer's disease, and brain injury. Here, we present simultaneous, microscopic measurements of cerebral blood flow (CBF) and oxygen partial pressure (pO2) in cortical microvessels of anesthetized rats under baseline conditions and during somatosensory stimulation. Using a custom-built imaging system, we measured CBF with Fourier-domain optical coherence tomography (OCT), and vascular pO2 with confocal phosphorescence lifetime microscopy. Cerebral blood flow and pO2 measurements displayed heterogeneity over distances irresolvable with fMRI and positron emission tomography. Baseline measurements indicate O2 extraction from pial arterioles and homogeneity of ascending venule pO2 despite large variation in microvessel flows. Oxygen extraction is linearly related to flow in ascending venules, suggesting that flow in ascending venules closely matches oxygen demand of the drained territory. Oxygen partial pressure and relative CBF transients during somatosensory stimulation further indicate arteriolar O2 extraction and suggest that arterioles contribute to the fMRI blood oxygen level dependent response. Understanding O2 supply on a microscopic level will yield better insight into brain function and the underlying mechanisms of various neuropathologies.

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Journal of Cerebral Blood Flow and Metabolism

Tập 31 Số 4

1051-1063

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