title: Cerebrovascular and ventilatory responses to acute isocapnic hypoxia in healthy aging and lung disease: effect of vitamin C.
abstract: Acute hypoxia increases cerebral blood flow (CBF) and ventilation (V̇e). It is unknown if these responses are impacted with normal aging, or in patients with enhanced oxidative stress, such as (COPD). The purpose of the study was to 1) investigate the effects of aging and COPD on the cerebrovascular and ventilatory responses to acute hypoxia, and 2) to assess the effect of vitamin C on these responses during hypoxia. In 12 Younger, 14 Older, and 12 COPD, we measured peak cerebral blood flow velocity (V̄p; index of CBF), and V̇e during two 5-min periods of acute isocapnic hypoxia, under conditions of 1) saline-sham; and 2) intravenous vitamin C. Antioxidants [vitamin C, superoxide dismutase (SOD), glutathione peroxidase, and catalase], oxidative stress [malondialdehyde (MDA) and advanced protein oxidation product], and nitric oxide metabolism end products (NOx) were measured in plasma. Following the administration of vitamin C, vitamin C, SOD, catalase, and MDA increased, while NOx decreased. V̄p and V̇e sensitivity to hypoxia was reduced in Older by ∼60% (P < 0.02). COPD patients exhibited similar V̄p and V̇e responses to Older (P > 0.05). Vitamin C did not have an effect on the hypoxic V̇e response but selectively decreased the V̄p sensitivity in Younger only. These findings suggest a reduced integrative reflex (i.e., cerebrovascular and ventilatory) during acute hypoxemia in healthy older adults. Vitamin C does not appear to have a large influence on the cerebrovascular or ventilatory responses during acute hypoxia.
authors.affiliation: Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; and.
authors.forename: Sara E
authors.initials: SE
authors.lastname: Hartmann
authors.affiliation: Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; and.
authors.forename: Xavier
authors.initials: X
authors.lastname: Waltz
authors.affiliation: Department of Cardiac Sciences, University of Calgary, Calgary, Alberta, Canada; Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; and.
authors.forename: Christine K
authors.initials: CK
authors.lastname: Kissel
authors.affiliation: Department of Medicine, University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; and.
authors.forename: Lian
authors.initials: L
authors.lastname: Szabo
authors.affiliation: Department of Medicine, University of Calgary, Calgary, Alberta, Canada; Snyder Institute for Chronic Diseases. University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; and.
authors.forename: Brandie L
authors.initials: BL
authors.lastname: Walker
authors.affiliation: Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada; Department of Medicine, University of Calgary, Calgary, Alberta, Canada; Snyder Institute for Chronic Diseases. University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; and.
authors.forename: Richard
authors.initials: R
authors.lastname: Leigh
authors.affiliation: Department of Cardiac Sciences, University of Calgary, Calgary, Alberta, Canada; Department of Medicine, University of Calgary, Calgary, Alberta, Canada; Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; and.
authors.forename: Todd J
authors.initials: TJ
authors.lastname: Anderson
authors.affiliation: Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada; Department of Clinical Neuroscience University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada; Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; and Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada poulin@ucalgary.ca.
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Poulin
mesh_terms: D000222:Adaptation, Physiological; D061605:Administration, Intravenous; D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging; D000416:Alberta; D000975:Antioxidants / Q000008:administration & dosage*; D001205:Ascorbic Acid / Q000008:administration & dosage*; D015415:Biomarkers / Q000097:blood; D001783:Blood Flow Velocity; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D008168:Lung / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000187:drug effects; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D012123:Pulmonary Ventilation / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000097:blood; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D017382:Reactive Oxygen Species; D001205:Ascorbic Acid
keywords: aging; chronic obstructive pulmonary disease; nitric oxide metabolism; oxidative stress; transcranial Doppler ultrasound