Response of mouse brain perfusion to hypo- and hyperventilation measured by arterial spin labeling

• Published in: Magnetic resonance in medicine 2011-09, Vol.66 (3), p.802-811
• Main Authors: Oosterlinck, W. Wouter, Dresselaers, T., Geldhof, V., Van Santvoort, A., Robberecht, W., Herijgers, P., Himmelreich, U.
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Animals; arterial spin labeling; Blood Flow Velocity; Blood Gas Analysis; Brain - blood supply; Brain - physiopathology; brain perfusion; Cerebrovascular Circulation; cerebrovascular response; Cross-Over Studies; Hypercapnia - physiopathology; Hyperventilation - physiopathology; Image Interpretation, Computer-Assisted - methods; Magnetic Resonance Imaging - instrumentation; Magnetic Resonance Imaging - methods; Mice; Mice, Inbred C57BL; Spin Labels; ventilation
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.23060

We aimed to setup a noninvasive and well‐controlled methodology for evaluation of the cerebrovascular response in mice (C57BL/6J; 12 weeks). Therefore we applied a normo‐, hypo‐, and hyperventilation paradigm combined with arterial spin labeling and monitoring of the expired CO2 (expCO2) (n = 7) or arterial pCO2 (apCO2) (n = 12). Reducing the tidal volume by 25% and the respiratory rate by 20% resulted in hypercapnia (apCO2 from 33 ± 6 mmHg to 64 ± 16 mmHg). Increasing the respiratory rate by 25% and the tidal volume by 20% decreased apCO2 to 22 ± 5 mmHg. Cerebral blood flow (CBF) was 82 ± 21, 163 ± 41 and 64 ± 18 mL/100 g/min during normo, hypo‐, and hyperventilation, respectively (midbrain). The correlation of apCO2 and CBF levels resulted in a cerebrovascular response of 2.7 ± 0.3, 2.1 ± 0.3, 2.1 ± 0.3, and 3.7 ± 0.5 mL/100 g/min/mmHg for midbrain, cortex, hippocampus and thalamus, respectively. As expCO2 levels were correlated with apCO2 (r2 = 0.86; n = 4) and CBF (r2 = 0.67) a cerebrovascular response based on simultaneously recorded CBF and expCO2 levels could be derived (3.3 ± 0.5, 2.5 ± 0.4, 3.0 ± 0.4, and 4.5 ± 0.6 mL/100 g/min/mmHg; order as above). A cross‐over experiment resulted in similar responses. In conclusion, this protocol allows evaluating basal CBF and cerebrovascular response in mice under well‐controlled conditions by simply changing ventilator settings and correlating CBF with apCO2 and/or simultaneously obtained expCO2. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.