title: Increased serum NG-hydroxy-L-arginine in patients with rheumatoid arthritis and systemic lupus erythematosus as an index of an increased nitric oxide synthase activity.
abstract: OBJECTIVE
  To determine the feasibility of monitoring the serum concentration of NG-hydroxy-L-arginine (L-NHA) as an index of an increased nitric oxide (NO) synthase activity in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) compared with nitrate (NO3-), the major circulating metabolite of NO whose concentration is influenced by dietary intake.
  
  
  METHODS
  The serum concentrations of L-NHA, L-arginine (L-Arg), and NO3- were determined in 33 patients with RA, 25 patients with SLE and, 29 healthy subjects.
  
  
  RESULTS
  Serum L-NHA was significantly increased in RA patients with high disease activity (287% of control, p < 0.01), but not with low disease activity (115%), as well as in patients with SLE (173%, p < 0.01). In contrast, serum NO3- did not differ significantly between either group of patients and the respective control group.
  
  
  CONCLUSIONS
  NO synthase activity or expression, or both, is upregulated in RA patients with high disease activity and in patients with SLE. Serum L-NHA seems to be a more specific and reliable index of an increased activity of this enzyme in patients with acute or chronic inflammatory diseases than NO3-.
authors.affiliation: Centre of Physiology, Johann Woifgang Goethe University Clinic, Frankfurt Main, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Wigand
authors.forename: J
authors.initials: J
authors.lastname: Meyer
authors.forename: R
authors.initials: R
authors.lastname: Busse
authors.forename: M
authors.initials: M
authors.lastname: Hecker
mesh_terms: D000208:Acute Disease; D001120:Arginine / Q000031:analogs & derivatives* / Q000097:blood; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000201:enzymology; D015415:Biomarkers / Q000097:blood; D004789:Enzyme Activation; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000201:enzymology; D008297:Male; D009566:Nitrates / Q000097:blood; D019001:Nitric Oxide Synthase / Q000378:metabolism
chemical_list: D015415:Biomarkers; D009566:Nitrates; C068309:N(omega)-hydroxyarginine; D001120:Arginine; D019001:Nitric Oxide Synthase