title: Modulation of NADPH oxidase activity by known uraemic retention solutes.
abstract: BACKGROUND
  Uraemia and cardiovascular disease appear to be associated with an increased oxidative burden. One of the key players in the genesis of reactive oxygen species (ROS) is nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Based on initial experiments demonstrating a decreased inhibitory effect on NADPH oxidase activity in the presence of plasma from patients with CKD-5D after dialysis compared with before dialysis, we investigated the effect of 48 known and commercially available uraemic retention solutes on the enzymatic activity of NADPH oxidase.
  
  
  METHODS
  Mononuclear leucocytes isolated from buffy coats of healthy volunteers were isolated, lysed and incubated with NADH in the presence of plasma from healthy controls and patients with CKD-5D. Furthermore, the leucocytes were lysed and incubated in the presence of uraemic retention solute of interest and diphenyleneiodonium chloride (DPI), an inhibitor of NADPH oxidase. The effect on enzymatic activity of NADPH oxidase was quantified within an incubation time of 120 min.
  
  
  RESULTS
  Thirty-nine of the 48 uraemic retention solutes tested had a significant decreasing effect on NADPH oxidase activity. Oxalate has been characterized as the strongest inhibitor of NADPH oxidase (90% of DPI inhibition). Surprisingly, none of the uraemic retention solutes we investigated was found to increase NADPH oxidase activity. Furthermore, plasma from patients with CKD-5D before dialysis caused significantly higher inhibitory effect on NADPH oxidase activity compared with plasma from healthy subjects. However, this effect was significantly decreased in plasma from patients with CKD-5D after dialysis.
  
  
  CONCLUSIONS
  The results of this study show that uraemic retention solutes modulated the activity of the NADPH oxidase. The results of this study might be the basis for the development of inhibitors applicable as drug in the situation of increased oxidative stress.
authors.affiliation: Charité-Universitätsmedizin Berlin (CBF), Medizinische Klinik IV, Berlin, Germany.
authors.forename: Anna Marta
authors.initials: AM
authors.lastname: Schulz
authors.forename: Cindy
authors.initials: C
authors.lastname: Terne
authors.forename: Vera
authors.initials: V
authors.lastname: Jankowski
authors.forename: Gerald
authors.initials: G
authors.lastname: Cohen
authors.forename: Mandy
authors.initials: M
authors.lastname: Schaefer
authors.forename: Falko
authors.initials: F
authors.lastname: Boehringer
authors.forename: Martin
authors.initials: M
authors.lastname: Tepel
authors.forename: Desiree
authors.initials: D
authors.lastname: Kunkel
authors.forename: Walter
authors.initials: W
authors.lastname: Zidek
authors.forename: Joachim
authors.initials: J
authors.lastname: Jankowski
mesh_terms: D000328:Adult; D001685:Biological Factors / Q000494:pharmacology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000201:enzymology; D008297:Male; D019255:NADPH Oxidases / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology; D010949:Plasma / Q000502:physiology; D017382:Reactive Oxygen Species / Q000494:pharmacology; D006435:Renal Dialysis; D051436:Renal Insufficiency, Chronic / Q000201:enzymology* / Q000628:therapy; D014511:Uremia / Q000201:enzymology*
chemical_list: D001685:Biological Factors; D017382:Reactive Oxygen Species; D019255:NADPH Oxidases
keywords: NADPH oxidase; oxidative stress; uraemic retention solutes