title: Effects of antioxidants (AREDS medication) on ocular blood flow and endothelial function in an endotoxin-induced model of oxidative stress in humans.
abstract: OBJECTIVE
  The Age-Related Eye Disease Study (AREDS) has shown that supplementation of antioxidants slows the progression of age-related macular degeneration (AMD). The mechanism underlying this therapeutic effect may be related to a reduction of reactive oxygen species (ROS). The authors have recently introduced a model showing that the response of retinal blood flow (RBF) to hyperoxia is diminished by administration of lipopolysaccharide (LPS). In the present study, the hypothesis was that this response can be restored by the AREDS medication.
  
  
  METHODS
  Twenty-one healthy volunteers were included in this randomized, double-masked, placebo-controlled, parallel group study. On each study day, RBF and the reactivity of RBF to hyperoxia were investigated before and after infusion of 2 ng/kg LPS. Between the two study days, subjects took either the AREDS medication or placebo for 14 days.
  
  
  RESULTS
  After administration of LPS reduced retinal arterial vasoconstriction during hyperoxia (AREDS group: 12.5% +/- 4.8% pre-LPS vs. 9.4% +/- 4.6% post-LPS; placebo group: 9.2% +/- 3.3% pre-LPS vs. 7.1% +/- 3.5% post-LPS) and a reduced reactivity of RBF during hyperoxia (AREDS: 50.4% +/- 8.9% vs. 44.9% +/- 11.6%, placebo: 54.2% +/- 8.6% vs. 46.0% +/- 6.9%) was found. The reduced responses were normalized after 2 weeks of AREDS antioxidants but not after placebo (vasoconstriction: 13.1% +/- 4.5% vs. 13.1% +/- 5.0% AREDS, 11.2% +/- 4.2 vs. 7.4% +/- 4.2% placebo; RBF: 52.8% +/- 10.5% vs. 52.4% +/- 10.5% AREDS, 52.4% +/- 9.3% vs. 44.2% +/- 6.3% placebo).
  
  
  CONCLUSIONS
  The sustained retinal vascular reaction to hyperoxia after LPS in the AREDS group indicates that antioxidants reduce oxidative stress-induced endothelial dysfunction, possibly by eliminating ROS. The model may be an attractive approach to studying the antioxidative capacity of dietary supplements for the treatment of AMD (ClinicalTrials.gov number, NCT00431691).
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Berthold
authors.initials: B
authors.lastname: Pemp
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Polska
authors.forename: Katharina
authors.initials: K
authors.lastname: Karl
authors.forename: Michael
authors.initials: M
authors.lastname: Lasta
authors.forename: Alexander
authors.initials: A
authors.lastname: Minichmayr
authors.forename: Gerhard
authors.initials: G
authors.lastname: Garhofer
authors.forename: Michael
authors.initials: M
authors.lastname: Wolzt
authors.forename: Leopold
authors.initials: L
authors.lastname: Schmetterer
mesh_terms: D000293:Adolescent; D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage*; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000097:blood; D001783:Blood Flow Velocity; D003300:Copper / Q000008:administration & dosage; D004311:Double-Blind Method; D004730:Endothelium, Vascular / Q000502:physiology*; D004731:Endotoxins; D006801:Humans; D018496:Hyperoxia / Q000503:physiopathology*; D007429:Intraocular Pressure; D017078:Laser-Doppler Flowmetry; D008070:Lipopolysaccharides; D008297:Male; D008954:Models, Biological; D018384:Oxidative Stress; D017382:Reactive Oxygen Species; D012039:Regional Blood Flow / Q000502:physiology; D012171:Retinal Vessels / Q000502:physiology*; D014661:Vasoconstriction; D014810:Vitamin E / Q000008:administration & dosage / Q000097:blood; D055815:Young Adult; D015034:Zinc Oxide / Q000008:administration & dosage; D019207:beta Carotene / Q000008:administration & dosage
chemical_list: D000975:Antioxidants; D004731:Endotoxins; D008070:Lipopolysaccharides; D017382:Reactive Oxygen Species; D019207:beta Carotene; D014810:Vitamin E; C044101:endotoxin, Escherichia coli; D003300:Copper; D001205:Ascorbic Acid; D015034:Zinc Oxide; C030973:cupric oxide