UBC-Nepal expedition: The use of oral antioxidants does not alter cerebrovascular function at sea-level or high-altitude
Hansen, Alex B.
Hoiland, Ryland L.
Lewis, Nia C. S.
Tymko, Michael M.
Tremblay, Joshua C.
Carter, Howard H.
Bailey, Damian M.
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Hypoxia is associated with an increased systemic and cerebral formation of free radicals and associated reactants that may be linked to impaired cerebral vascular function a neurological sequela. To what extent oral antioxidants prophylaxis impacts cerebrovascular function in humans throughout the course of acclimatization to the hypoxia of terrestrial high-altitude has not been examined. Thus, the purpose of the current study was to examine the influence of orally ingested antioxidants at clinically relevant doses (vitamin C, E, and alpha-lipoic acid) on cerebrovascular regulation at sea-level (344 m; n = 12; female n = 2 participants), and at high altitude (5050 m; n = 9; female n = 2), in a randomized, placebo-controlled, and double-blinded crossover design. Hypercapnic and hypoxic cerebrovascular reactivity tests of the internal carotid (ICA)] were conducted at sea-level, while global and regional cerebral blood flow [i.e. ICA and vertebral artery (VA)] were assessed after 10–12 days following arrival at 5050 m. At sea-level, acute administration of antioxidants did not alter cerebral hypoxic cerebrovascular reactivity (pre vs. post: 1.5 ± 0.7 vs. 1.2 ± 0.8 %∆CBF/-%∆SpO2; P = 0.96), or cerebral hypercapnic cerebrovascular reactivity (pre vs. post: 5.7 ± 2.0 vs. 5.8 ± 1.9 %∆CBF/∆mmHg; P = 0.33). Furthermore, global cerebral blood flow (P = 0.43), as well as cerebral vascular conductance (ICA P = 0.08; VA P = 0.32), were unaltered at 5050 m following antioxidant administration. In conclusion, these data show that an oral antioxidant cocktail known to attenuate systemic oxidative stress failed to alter cerebrovascular function at sea-level and cerebral blood flow during acclimatization to high-altitude.
Hansen, A.B., Hoiland, R.L., Lewis, N., Tymko, M.M., Tremblay, J.C., Stembridge, M., Nowak‐Flück, D., Carter, H.H., Bailey, D.M. and Ainslie, P.N. (2018) 'UBC‐Nepal expedition: The use of oral antioxidants does not alter cerebrovascular function at sea‐level or high‐altitude', Experimental Physiology. https://doi.org/10.1113/EP086887
This article was published in Experimental Physiology on 10 February 2018 (online), available at https://doi.org/10.1113/EP086887
Cardiff Metropolitan University (Grant ID: Cardiff Metropolian (Internal))
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