title: Exercise-mediated vasodilation in human obesity and metabolic syndrome: effect of acute ascorbic acid infusion.
abstract: We tested the hypothesis that infusion of ascorbic acid (AA), a potent antioxidant, would alter vasodilator responses to exercise in human obesity and metabolic syndrome (MetSyn). Forearm blood flow (FBF, Doppler ultrasound) was measured in lean, obese, and MetSyn adults (n = 39, 32 ± 2 yr). A brachial artery catheter was inserted for blood pressure monitoring and local infusion of AA. FBF was measured during dynamic handgrip exercise (15% maximal effort) with and without AA infusion. To account for group differences in blood pressure and forearm size, and to assess vasodilation, forearm vascular conductance (FVC = FBF/mean arterial blood pressure/lean forearm mass) was calculated. We examined the time to achieve steady-state FVC (mean response time, MRT) and the rise in FVC from rest to steady-state exercise (Δ, exercise - rest) before and during acute AA infusion. The MRT (P = 0.26) and steady-state vasodilator responses to exercise (ΔFVC, P = 0.31) were not different between groups. Intra-arterial infusion of AA resulted in a significant increase in plasma total antioxidant capacity (174 ± 37%). AA infusion did not alter MRT or steady-state FVC in any group (P = 0.90 and P = 0.85, respectively). Interestingly, higher levels of C-reactive protein predicted longer MRT (r = 0.52, P < 0.01) and a greater reduction in MRT with AA infusion (r = -0.43, P = 0.02). We concluded that AA infusion during moderate-intensity, rhythmic forearm exercise does not alter the time course or magnitude of exercise-mediated vasodilation in groups of young lean, obese, or MetSyn adults. However, systemic inflammation may limit the MRT to exercise, which can be improved with AA.
authors.affiliation: Department of Kinesiology, School of Education, University of Wisconsin, and.
authors.forename: Jacqueline K
authors.initials: JK
authors.lastname: Limberg
authors.affiliation: Department of Kinesiology, School of Education, University of Wisconsin, and.
authors.forename: J Mikhail
authors.initials: JM
authors.lastname: Kellawan
authors.affiliation: Department of Kinesiology, School of Education, University of Wisconsin, and.
authors.forename: John W
authors.initials: JW
authors.lastname: Harrell
authors.affiliation: Department of Kinesiology, School of Education, University of Wisconsin, and.
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Johansson
authors.affiliation: Departments of Pediatrics and.
authors.forename: Marlowe W
authors.initials: MW
authors.lastname: Eldridge
authors.affiliation: Anesthesiology, School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, Wisconsin.
authors.forename: Lester T
authors.initials: LT
authors.lastname: Proctor
authors.affiliation: Anesthesiology, School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, Wisconsin.
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Sebranek
authors.affiliation: Department of Kinesiology, School of Education, University of Wisconsin, and wschrage@education.wisc.edu.
authors.forename: William G
authors.initials: WG
authors.lastname: Schrage
mesh_terms: D000293:Adolescent; D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage*; D062186:Arterial Pressure; D001205:Ascorbic Acid / Q000008:administration & dosage*; D015415:Biomarkers / Q000097:blood; D001783:Blood Flow Velocity; D001916:Brachial Artery / Q000187:drug effects* / Q000503:physiopathology; D002097:C-Reactive Protein / Q000378:metabolism; D015444:Exercise; D005260:Female; D005542:Forearm / Q000098:blood supply*; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood; D007261:Infusions, Intra-Arterial; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology*; D009765:Obesity / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology*; D012039:Regional Blood Flow; D013997:Time Factors; D014664:Vasodilation / Q000187:drug effects*; D055815:Young Adult
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D018836:Inflammation Mediators; D002097:C-Reactive Protein; D001205:Ascorbic Acid
keywords: antioxidant; blood flow; reactive oxygen species