Blood Flow during Handgrip Exercise in COPD: Effect of Vitamin C.
OBJECTIVE
Chronic obstructive pulmonary disease (COPD) is associated with vascular dysfunction, possibly related to increased oxidative stress. Exercise hyperemia may similarly be impaired, which could have implications for exercise limitations in COPD. We tested if brachial blood flow (BBF) was reduced during handgrip exercise in COPD and if this response would be improved after vitamin C infusion.


METHODS
Doppler ultrasound was used to measure brachial blood flow and vascular conductance (BBF and BVC, respectively) during mild, rhythmic handgrip exercise (EX) under conditions of sham-saline and vitamin C. Measures of flow-mediated dilation (FMD) and nitroglycerine-mediated dilation were used to assess endothelial-dependent and independent dilation, respectively. Biomarkers of antioxidants (vitamin C, superoxide dismutase [SOD], catalase), oxidative stress (malondialdehyde [MDA], advanced oxidation protein products [AOPP]), and nitric oxide metabolism (NOx) were measured in blood plasma.


RESULTS
Ten COPD patients with moderate COPD and 10 healthy age-matched controls participated. COPD patients had similar increases in BBF and BVC during EX, compared with controls. Vitamin C was not found to have an effect on blood flow parameters during exercise (P > 0.05). Markers of endothelial-dependent dilation (FMD) and nitroglycerin-mediated dilation were similar between groups at baseline; FMD improved similarly in both groups after vitamin C.


CONCLUSIONS
Moderate COPD patients have a preserved BBF response during handgrip exercise and do not exhibit endothelial dysfunction. Despite an increase in endothelial-dependent dilation after vitamin C, BBF remained unchanged, suggesting a limited impact of endothelial-derived NO in determining the blood flow response to handgrip exercise in older individuals. COPD patients of moderate severity, screened for cardiovascular disease, do not exhibit endothelial dysfunction and have similar exercise blood flow responses to healthy controls.
1Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, CANADA; 2Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, CANADA; 3Cumming School of Medicine, University of Calgary, Calgary, Alberta, CANADA; 4Department of Medicine, University of Calgary, Calgary, Alberta, CANADA; 5Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta, CANADA; 6Department of Cardiac Sciences, University of Calgary, Calgary, Alberta, CANADA; 7Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, CANADA; 8Department of Clinical Neuroscience, University of Calgary, Calgary, Alberta, CANADA; and 9Faculty of Kinesiology, University of Calgary, Calgary, Alberta, CANADA.
Sara E
SE
Hartmann
Xavier
X
Waltz
Richard
R
Leigh
Todd J
TJ
Anderson
Marc J
MJ
Poulin
D000368:Aged; D000975:Antioxidants / Q000008:administration & dosage*; D001205:Ascorbic Acid / Q000008:administration & dosage*; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D004730:Endothelium, Vascular / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D018384:Oxidative Stress / Q000502:physiology; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012039:Regional Blood Flow / Q000187:drug effects*; D014463:Ultrasonography; D014664:Vasodilation / Q000187:drug effects
D000975:Antioxidants; D001205:Ascorbic Acid