title: Long-term adaptation of cerebral hemodynamic response to somatosensory stimulation during chronic hypoxia in awake mice.
abstract: Effects of chronic hypoxia on hemodynamic response to sensory stimulation were investigated. Using laser-Doppler flowmetry, change in cerebral blood flow (CBF) was measured in awake mice, which were housed in a hypoxic chamber (8% O₂) for 1 month. The degree of increase in CBF evoked by sensory stimulation was gradually decreased over 1 month of chronic hypoxia. No significant reduction of increase in CBF induced by hypercapnia was observed during 1 month. Voltage-sensitive dye (VSD) imaging of the somatosensory cortex showed no significant decrease in neural activation over 1 month, indicating that the reduction of increase in CBF to sensory stimulation was not caused by cerebrovascular or neural dysfunction. The simulation study showed that, when effective diffusivity for oxygen in the capillary bed (D) value increases by chronic hypoxia due to an increase in capillary blood volume, an increase in the cerebral metabolic rate of oxygen utilization during neural activation can occur without any increase in CBF. Although previous study showed no direct effects of acute hypoxia on CBF response, our finding showed that hemodynamic response to neural activation could be modified in response to a change in their balance to energy demand using chronic hypoxia experiments.
authors: Biophysics Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan.
authors: Hiroyuki
authors: H
authors: Takuwa
authors: Kazuto
authors: K
authors: Masamoto
authors: Kyoko
authors: K
authors: Yamazaki
authors: Hiroshi
authors: H
authors: Kawaguchi
authors: Yoko
authors: Y
authors: Ikoma
authors: Yousuke
authors: Y
authors: Tajima
authors: Takayuki
authors: T
authors: Obata
authors: Yutaka
authors: Y
authors: Tomita
authors: Norihiro
authors: N
authors: Suzuki
authors: Iwao
authors: I
authors: Kanno
authors: Hiroshi
authors: H
authors: Ito
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001835:Body Weight; D001921:Brain / Q000098:blood supply* / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D002560:Cerebrovascular Circulation; D004734:Energy Metabolism; D006400:Hematocrit; D006439:Hemodynamics; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology*; D017078:Laser-Doppler Flowmetry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008833:Microcirculation; D010100:Oxygen / Q000378:metabolism; D012677:Sensation; D014851:Wakefulness
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
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