title: Increased ventilatory response to carbon dioxide in COPD patients following vitamin C administration.
abstract: Patients with chronic obstructive pulmonary disease (COPD) have decreased ventilatory and cerebrovascular responses to hypercapnia. Antioxidants increase the ventilatory response to hypercapnia in healthy humans. Cerebral blood flow is an important determinant of carbon dioxide/hydrogen ion concentration at the central chemoreceptors and may be affected by antioxidants. It is unknown whether antioxidants can improve the ventilatory and cerebral blood flow response in individuals in whom these are diminished. Thus, we aimed to determine the effect of vitamin C administration on the ventilatory and cerebrovascular responses to hypercapnia during healthy ageing and in COPD. Using transcranial Doppler ultrasound, we measured the ventilatory and cerebral blood flow responses to hyperoxic hypercapnia before and after an intravenous vitamin C infusion in healthy young (Younger) and older (Older) subjects and in moderate COPD. Vitamin C increased the ventilatory response in COPD patients (mean (95% CI) 1.1 (0.9-1.1)versus1.5 (1.1-2.0) L·min-1·mmHg-1, p<0.05) but not inYounger(2.5 (1.9-3.1)versus2.4 (1.9-2.9) L·min-1·mmHg-1, p>0.05) orOlder(1.3 (1.0-1.7)versus1.3 (1.0-1.7) L·min-1·mmHg-1, p>0.05) healthy subjects. Vitamin C did not affect the cerebral blood flow response in the young or older healthy subjects or COPD subjects (p>0.05). Vitamin C increases the ventilatory but not cerebrovascular response to hyperoxic hypercapnia in patients with moderate COPD.
authors.affiliation: Dept of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada; Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
authors.forename: Sara E
authors.initials: SE
authors.lastname: Hartmann
authors.affiliation: Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Dept of Cardiac Sciences, University of Calgary, Calgary, AB, Canada; Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada.
authors.forename: Christine K
authors.initials: CK
authors.lastname: Kissel
authors.affiliation: Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Dept of Medicine, University of Calgary, Calgary, AB, Canada.
authors.forename: Lian
authors.initials: L
authors.lastname: Szabo
authors.affiliation: Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Dept of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada.
authors.forename: Brandie L
authors.initials: BL
authors.lastname: Walker
authors.affiliation: Dept of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada; Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Dept of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Leigh
authors.affiliation: Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Dept of Cardiac Sciences, University of Calgary, Calgary, AB, Canada; Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada; Dept of Medicine, University of Calgary, Calgary, AB, Canada.
authors.forename: Todd J
authors.initials: TJ
authors.lastname: Anderson
authors.affiliation: Dept of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada; Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada; Dept of Clinical Neuroscience, University of Calgary, Calgary, AB, Canada; Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Poulin