CO2 response for the brain stem artery blood flow velocity in man

Wataru Hida, Yoshihiro Kikuchi, Shinichi Okabe, Hiroshi Miki, Hajime Kurosawa, Kunio Shirato

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


We examined changes in the blood flow velocity of brain stem artery (BSA) and middle cerebral artery (MCA) in response to hypercapnic, normocapnic and hypocapnic hyperventilation in seven awake subjects with a transcranial Doppler to determine if there are differences in blood flow control in regional brain perfused by these respective arteries, and to separate the effects of CO2 and ventilation itself on blood flow velocity during CO2 loading. During hypercapnic hyperventilation, BSA flow velocity increased linearly with an increase in end-tidal partial pressure of CO2 (PET(CO2)) During hypocapnic hyperventilation, BSA flow velocity decreased linearly with decrease in PET(CO2) but did not change during normocapnic hyperventilation. The mean CO2 reactivity of BSA was 2.8%/mmHg. The responses of MCA to these hyperventilations and CO2 reactivity were similar to those of BSA. These findings suggest that CO2 rather than ventilation per se is the important stimulus to changes in brain blood flow velocity and that the CO2 responses of brain arteries are not affected by differences in vascular beds.

Original languageEnglish
Pages (from-to)71-75
Number of pages5
JournalRespiration Physiology
Issue number1
Publication statusPublished - 1996 Jan 1


  • Blood flow, brain
  • Brain, blood flow, CO
  • Carbon dioxide, brain blood flow
  • Hypercapnia, brain blood flow
  • Mammals, humans

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine


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