Effects of continuous hypoxia on flow-mediated dilation in the cerebral and systemic circulation: on the regulatory significance of shear rate phenotype

Shigehiko Ogoh, Takuro Washio, Benjamin Stacey, Hayato Tsukamoto, Angelo Iannetelli, Tom Owens, Thomas A. Calverley, Lewis Fall, Christopher Marley, Damian Bailey

Research output: Contribution to journalArticlepeer-review

Abstract

Emergent evidence suggests that cyclic intermittent hypoxia increases cerebral arterial shear rate and endothelial function, whereas continuous exposure decreases anterior cerebral oxygen (O2) delivery. To examine to what extent continuous hypoxia impacts cerebral shear rate, cerebral endothelial function, and consequent cerebral O2 delivery (CDO2), eight healthy males were randomly assigned single-blind to 7 h passive exposure to both normoxia (21% O2) and hypoxia (12% O2). Blood flow in the brachial and internal carotid arteries were determined using Duplex ultrasound and included the combined assessment of systemic and cerebral endothelium-dependent flow-mediated dilatation. Systemic (brachial artery) flow-mediated dilatation was consistently lower during hypoxia (P = 0.013 vs. normoxia), whereas cerebral flow-mediated dilation remained preserved (P = 0.927 vs. normoxia) despite a reduction in internal carotid artery antegrade shear rate (P = 0.002 vs. normoxia) and CDO2 (P < 0.001 vs. normoxia). Collectively, these findings indicate that the reduction in CDO2 appears to be independent of cerebral endothelial function and contrasts with that observed during cyclic intermittent hypoxia, highlighting the regulatory importance of (hypoxia) dose duration and flow/shear rate phenotype.
Original languageEnglish
Article number16
Pages (from-to)16
Number of pages13
JournalThe Journal of Physiological Sciences
Volume72
Issue number1
Early online date20 Jul 2022
DOIs
Publication statusE-pub ahead of print - 20 Jul 2022

Keywords

  • Hypoxia
  • Cerebral blood flow
  • flow-mediated dilation
  • Endothelial function
  • Antegrade shear rate
  • Retrograde shear rate

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