Tajima Yosuke, Takuwa Hiroyuki, Nishino Asuka, Matsuura Tetsuya, Kawaguchi Hiroshi, Ikoma Yoko, Taniguchi Junko, Seki Chie, Masamoto Kazuto, Kanno Iwao, Saeki Naokatsu, Ito Hiroshi
Department of Biophysics Program, Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, Japan; Department of Neurological Surgery, Chiba University Graduate School of Medicine, Chiba, Japan.
Department of Biophysics Program, Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, Japan.
Brain Res. 2014 Apr 4;1557:155-63. doi: 10.1016/j.brainres.2014.01.053. Epub 2014 Feb 6.
Cerebral hemodynamic response to acute hyperoxia was investigated in awake mice. Using laser-Doppler flowmetry (LDF), baseline cerebral blood flow (CBF) and the cerebrovascular responses to whisker stimulation were measured in awake mice during normoxia and hyperoxia. Using two-photon laser scanning microscopy (TPLSM), the changes in cortical microvasculature were measured during normoxia and hyperoxia. During hyperoxia (PaO2=482.3±19.7mmHg), baseline CBF was 6.8% lower than normoxia (PaO2=97.3±6.0mmHg). The degree of increase in CBF evoked by whisker stimulation was greater during hyperoxia (18.1±5.0%) than normoxia (13.1±3.5%) (P<0.05). TPLSM imaging of the somatosensory cortex showed vasconstriction in arterioles and capillaries during hyperoxia. Since the effective diffusivity for oxygen in the capillary bed might decrease by hyperoxia due to a decrease in capillary blood volume according to Hyder׳s model, an increase in the cerebral metabolic rate of oxygen utilization by neural activation during hyperoxia might need a greater increase in CBF as compared with normoxia. The hemodynamic response to neural activation could be modified by acute hyperoxia due to modification of the relation between changes in CBF and oxygen consumption by neural activation.
在清醒小鼠中研究了大脑对急性高氧的血流动力学反应。使用激光多普勒血流仪（LDF），在常氧和高氧条件下测量清醒小鼠的基线脑血流量（CBF）以及对触须刺激的脑血管反应。使用双光子激光扫描显微镜（TPLSM），测量常氧和高氧条件下皮质微血管的变化。在高氧（PaO2 = 482.3±19.7mmHg）期间，基线CBF比常氧（PaO2 = 97.3±6.0mmHg）时低6.8%。触须刺激引起的CBF增加程度在高氧（18.1±5.0%）时大于常氧（13.1±3.5%）（P<0.05）。体感皮层的TPLSM成像显示高氧期间小动脉和毛细血管收缩。根据海德模型，由于毛细血管血容量减少，高氧可能会使毛细血管床中氧气的有效扩散率降低，因此与常氧相比，高氧期间神经激活引起的脑氧代谢率增加可能需要更大幅度的CBF增加。由于神经激活引起的CBF变化与氧消耗之间关系的改变，急性高氧可改变对神经激活的血流动力学反应。
