title: Effect of oxygen on relaxation of retinal pericytes by sodium nitroprusside.
abstract: BACKGROUND
  This study addresses whether oxygen modulates the relaxation induced in retinal pericytes by sodium nitroprusside (SNP), a nitric oxide (NO) donor that stimulates the NO/guanylate cyclase pathway.
  
  
  METHODS
  Bovine retinal pericytes were cultured on silicone. On the silicone surface, basal pericyte contractile tone induces wrinkles. Drug-induced changes in pericyte contractile tone were assessed by changes in the number of wrinkles. The effects of 100% nitrogen (hypoxia) and 100% oxygen (hyperoxia) were studied on: (a) the basal tone of quiescent pericytes, (b) the relaxation to 3 and 10 microM SNP or 1 microM forskolin, and (c) the recontraction that followed the washout of 3 microM SNP or 1 microM forskolin.
  
  
  RESULTS
  Neither hypoxia nor hyperoxia had any apparent influence on pericyte basal tone, on forskolin-induced relaxation, or on pericyte recontraction after a forskolin-induced relaxation. In hypoxia, relaxations to SNP 3 microM (P < 0.05) and 10 microM (P < 0.01) were significantly more pronounced than in hyperoxia. Hypoxia also reduced the recontraction after an SNP-induced relaxation (P < 0.001).
  
  
  CONCLUSIONS
  Oxygen modulates the relaxation of bovine retinal pericytes evoked by SNP (guanylate cyclase-mediated), but not the relaxation induced by forskolin (adenylate cyclase-mediated). These results suggest that in the retinal capillary circulation an interaction between oxygen and the NO/guanylate cyclase pathway modulates pericyte tone, and thus potentially blood flow.
authors.affiliation: Laboratory for Ocular Pharmacology and Physiology, University Eye Clinic Basel, Switzerland.
authors.forename: I O
authors.initials: IO
authors.lastname: Haefliger
authors.forename: Q
authors.initials: Q
authors.lastname: Chen
authors.forename: D R
authors.initials: DR
authors.lastname: Anderson
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000187:drug effects / Q000378:metabolism; D018496:Hyperoxia / Q000378:metabolism / Q000503:physiopathology; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology; D008833:Microcirculation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism; D009584:Nitrogen / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology*; D010100:Oxygen / Q000494:pharmacology*; D012171:Retinal Vessels / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D014665:Vasodilator Agents; D009599:Nitroprusside; D005576:Colforsin; D009569:Nitric Oxide; D006162:Guanylate Cyclase; D009584:Nitrogen; D010100:Oxygen