title: Effect of different intensities of exercise on endothelium-dependent vasodilation in humans: role of endothelium-dependent nitric oxide and oxidative stress.
abstract: BACKGROUND
  Aerobic exercise enhances endothelium-dependent vasodilation in hypertensive patients, patients with chronic heart failure, and healthy individuals. However, it is unclear how the intensity of exercise affects endothelial function in humans. The purpose of the present study was to determine the effects of different intensities of exercise on endothelium-dependent vasodilation in humans.
  
  
  RESULTS
  We evaluated the forearm blood flow responses to acetylcholine, an endothelium-dependent vasodilator, and isosorbide dinitrate, an endothelium-independent vasodilator, before and after different intensities of exercise (mild, 25% VO2max; moderate, 50% VO2max; and high, 75% VO2max; bicycle ergometers, 30 minutes, 5 to 7 times per week for 12 weeks) in 26 healthy young men. Forearm blood flow was measured using a mercury-filled Silastic strain-gauge plethysmograph. Twelve weeks of moderate-intensity exercise, but not mild- or high-intensity exercise, significantly augmented acetylcholine-induced vasodilation (7.5+/-2.4 to 11.4+/-5.8 mL/min per 100 mL tissue; P<0.05). No intensity of aerobic exercise altered isosorbide dinitrate-induced vasodilation. The administration of NG-monomethyl-L-arginine, a nitric oxide synthase inhibitor, abolished the moderate-intensity exercise-induced augmentation of the forearm blood flow response to acetylcholine. High-intensity exercise increases plasma concentrations of 8-hydroxy-2'-deoxyguanosine (from 6.7+/-1.1 to 9.2+/-2.3 ng/mL; P<0.05) and serum concentrations of malondialdehyde-modified low-density lipoprotein (from 69.0+/-19.5 to 82.4+/-21.5 U/L; P<0.05), whereas moderate exercise tended to decrease both indices of oxidative stress.
  
  
  CONCLUSIONS
  These findings suggest that moderate-intensity aerobic exercise augments endothelium-dependent vasodilation in humans through the increased production of nitric oxide and that high-intensity exercise possibly increases oxidative stress.
authors.affiliation: Physical Therapy Health Sciences, School of Medicine, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan.
authors.forename: Chikara
authors.initials: C
authors.lastname: Goto
authors.forename: Yukihito
authors.initials: Y
authors.lastname: Higashi
authors.forename: Masashi
authors.initials: M
authors.lastname: Kimura
authors.forename: Kensuke
authors.initials: K
authors.lastname: Noma
authors.forename: Keiko
authors.initials: K
authors.lastname: Hara
authors.forename: Keigo
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Kawamura
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Chayama
authors.forename: Masao
authors.initials: M
authors.lastname: Yoshizumi
authors.forename: Isao
authors.initials: I
authors.lastname: Nara
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000328:Adult; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D004730:Endothelium, Vascular / Q000378:metabolism / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005542:Forearm / Q000098:blood supply; D006801:Humans; D007548:Isosorbide Dinitrate / Q000494:pharmacology; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D013995:Time; D014664:Vasodilation / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D014665:Vasodilator Agents; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D007548:Isosorbide Dinitrate; D000109:Acetylcholine