title: Circadian rhythmicity of whole-blood glutathione in healthy subjects.
abstract: OBJECTIVE
  Physiologic rhythms of antioxidants have been the subject of considerable interest in recent years. Physiologically, it is known that 24-h variability in whole-blood glutathione (GSH) could depend on various factors, such as meal composition, protein dietary content, meal-related hormonal modifications, and stress. Experiments were conducted to determine if the circadian variations previously observed in hepatic concentrations of reduced glutathione in animals also occurred in healthy volunteers.
  
  
  METHODS
  The circadian periodicity of whole-blood glutathione was explored. All parameters were measured enzymatically at 4-h intervals over a 24-h period.
  
  
  RESULTS
  Circadian rhythms were not found. The rhythms peak for glutathione content occurred at 9 h with a small peak at 21 h. The nadir occurred at 17 h and 1 h.
  
  
  CONCLUSIONS
  These data show that despite this wide distribution of glutathione throughout the day we could not find any significant intertime variability.
authors.forename: E
authors.initials: E
authors.lastname: Valencia
authors.forename: A
authors.initials: A
authors.lastname: Marin
authors.forename: G
authors.initials: G
authors.lastname: Hardy
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D003545:Cysteine / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D005260:Female; D005978:Glutathione / Q000008:administration & dosage / Q000097:blood*; D006706:Homeostasis; D006801:Humans; D008297:Male; D008715:Methionine / Q000008:administration & dosage; D010084:Oxidation-Reduction
chemical_list: D004044:Dietary Proteins; D008715:Methionine; D005978:Glutathione; D003545:Cysteine