Exercise-induced brachial artery vasodilation: role of free radicals

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 292; no. 3; pp. H1516 - H1522
• Main Authors: Richardson, Russell S, Donato, Anthony J, Uberoi, Abhimanyu, Wray, D. Walter, Lawrenson, Lesley, Nishiyama, Steven, Bailey, Damian M
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.03.2007
• Subjects: Adolescent; Adult; Antioxidants; Antioxidants - metabolism; Antioxidants - pharmacology; Arms; Ascorbic Acid - blood; Blood Flow Velocity - drug effects; Blood vessels; Brachial Artery - diagnostic imaging; Brachial Artery - physiology; Electron Spin Resonance Spectroscopy; Exercise - physiology; Exercise Test; Forearm - blood supply; Free Radicals - metabolism; Hand Strength; Humans; Male; Molecules; Oxidative Stress; Reference Values; Spectrum analysis; Studies; Ultrasonography, Doppler; Vasodilation - drug effects; Vasodilation - physiology; Veins & arteries; Vitamin E - blood
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.01045.2006

Physiology Division, Department of Medicine, University of California San Diego, La Jolla, California Submitted 22 September 2006 ; accepted in final form 10 November 2006 Originally thought of as simply damaging or toxic "accidents" of in vivo chemistry, free radicals are becoming increasingly recognized as redox signaling molecules implicit in cellular homeostasis. Indeed, at the vascular level, it is plausible that oxidative stress plays a regulatory role in normal vascular function. Using electron paramagnetic resonance (EPR) spectroscopy, we sought to document the ability of an oral antioxidant cocktail (vitamins C, E, and -lipoic acid) to reduce circulating free radicals, and we employed Doppler ultrasound to examine the consequence of an antioxidant-mediated reduction in oxidative stress on exercise-induced vasodilation. A total of 25 young (18–31 yr) healthy male subjects partook in these studies. EPR spectroscopy revealed a reduction in circulating free radicals following antioxidant administration at rest ( 98%) and as a consequence of exercise ( 85%). Plasma total antioxidant capacity and vitamin C both increased following the ingestion of the antioxidant cocktail, whereas vitamin E levels were not influenced by the ingestion of the antioxidants. Brachial artery vasodilation during submaximal forearm handgrip exercise was greater with the placebo (7.4 ± 1.8%) than with the antioxidant cocktail (2.3 ± 0.7%). These data document the efficacy of an oral antioxidant cocktail in reducing free radicals and suggest that, in a healthy state, the aggressive disruption of the delicate balance between pro- and antioxidant forces can negatively impact vascular function. These findings implicate an exercise-induced reliance upon pro-oxidant-stimulated vasodilation, thereby revealing an important and positive vascular role for free radicals. antioxidants; oxidative stress; electron paramagnetic resonance spectroscopy Address for reprint requests and other correspondence: R. S. Richardson, Dept. of Medicine, Physiology Division, 9500 Gilman Dr., Univ. of California San Diego, La Jolla, CA 92093-0623 (e-mail: rrichardson{at}ucsd.edu )