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Dynamic cerebral carbon dioxide reactivity at rest and during exercise
Author(s) -
Ogoh Shigehiko,
Shigeki Shibata,
Nakahara Hidehiro,
Miyamoto Tadayoshi
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.528.3
Subject(s) - hypercapnia , cerebral blood flow , hypocapnia , middle cerebral artery , cerebral autoregulation , cerebral arteries , anesthesia , vasodilation , carbon dioxide , cerebral circulation , medicine , vasoconstriction , cardiology , chemistry , respiratory system , ischemia , autoregulation , blood pressure , organic chemistry
The cerebral vasculature is highly sensitive to direct arterial carbon dioxide tension (PaCO 2 ) changes. Hypocapnia causes cerebral vasoconstriction, while hypercapnia causes cerebral vasodilation to maintain the brain tissue PCO 2 within narrow limits. The cerebral blood flow (CBF) responses to PaCO 2 changes should be quick, but the cerebral vasculature sensitivity as cerebral CO 2 is measured during steady‐state vascular responses. Therefore, the CBF time response to PaCO 2 changes remains unknown. The purpose of this study was to examine dynamic cerebral CO 2 reactivity at rest and during exercise using the frequency domain analysis. Seven healthy young subjects participated in the study. At rest and during exercise (30% VO 2 max and cycling exercise), the dynamic CO 2 reactivity was calculated based on the transfer function analysis between the end‐tidal CO 2 (P ET CO 2 ) and the middle cerebral artery mean blood velocity (MCAvm), using a binary white‐noise sequence (0%–7% inspired CO 2 fraction). Dynamic characteristics of the respiratory controller showed a low‐pass filter characteristic for regulating ventilation, and the dynamic gain was decreased gradually to 0.7 at 0.02 Hz. However, the gain from P ET CO 2 to MCAvm (dynamic CO 2 reactivity) remained reasonably constant up to 0.02 Hz. Moreover, it did not change during exercise. These findings suggest that the dynamic cerebral CO 2 reactivity is reflected in slow to fast PaCO 2 changes, and does not change during exercise. In terms of CO 2 homeostasis, the cerebral CO 2 reactivity may be a more important physiological mechanism to adapt to fast CO 2 changes than the ventilatory response to PaCO 2 changes. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .