title: Effect of acetazolamide on the optic disc oxygenation in miniature pigs.
abstract: BACKGROUND
  The purpose of our study was to evaluate the variations of the optic disc PO (2) during normoxia and hyperoxia (100 % O (2)), before and after intravenous administration of acetazolamide.
  
  
  METHODS
  PO (2) measurements were obtained at intervascular areas of the optic disc in 11 anaesthetized miniature pigs using oxygen-sensitive microelectrodes introduced through the vitreous cavity by a micromanipulator. PO (2) was measured continuously during 10 minutes under systemic normoxia and systemic hyperoxia. Oxygen measurements were repeated under these conditions after intravenous injection of acetazolamide (bolus of 500 mg) in 8 animals.
  
  
  RESULTS
  In systemic hyperoxia, the optic disc PO (2) increased moderately (DeltaPO (2) = 4.7 +/- 2.5 mmHg; p < 0.001; n = 11) in parallel with systemic PaO (2). Acetazolamide led to a slow and progressive increase in the optic disc PO (2) (DeltaPO (2) = 2.1 +/- 1.7 mmHg; p > 0.1; n = 8 after 10 min, while DeltaPO (2) = 4.3 +/- 3.2 mmHg; p < 0.05; n = 8 after 30 min), in parallel with a slow and progressive increase in systemic PaCO (2). The optic disc PO (2) increased much more significantly after injection of acetazolamide under systemic hyperoxia (DeltaPO (2) = 13.3 +/- 3.1 mmHg; p < 0.001; n = 8).
  
  
  CONCLUSIONS
  Systemic hyperoxia alone is not sufficient to increase substantially the optic disc PO (2) in miniature pigs due to a vasoconstrictor effect. Intravenous injection of acetazolamide can increase the optic disc PO (2) progressively, due to a vasodilatory effect of elevated systemic PaCO (2). The association of acetazolamide injection with systemic hyperoxia can further improve the oxygenation of the optic disc.
authors.affiliation: Department of Ophthalmology, University Hospitals of Geneva, Geneva, Switzerland.
authors.forename: I K
authors.initials: IK
authors.lastname: Petropoulos
authors.forename: J-A C
authors.initials: JA
authors.lastname: Pournaras
authors.forename: J-L
authors.initials: JL
authors.lastname: Munoz
authors.forename: C J
authors.initials: CJ
authors.lastname: Pournaras
mesh_terms: D000086:Acetazolamide / Q000494:pharmacology*; D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D002257:Carbonic Anhydrase Inhibitors / Q000494:pharmacology*; D007275:Injections, Intravenous; D009898:Optic Disk / Q000098:blood supply / Q000187:drug effects*; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000187:drug effects*; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D013552:Swine; D013556:Swine, Miniature
chemical_list: D002257:Carbonic Anhydrase Inhibitors; D002245:Carbon Dioxide; D000086:Acetazolamide; D010100:Oxygen