title: Continuous measurements of intra-vascular pO2 in the pig optic nerve head.
abstract: BACKGROUND
  The measurement of oxygen concentration in the microvasculature of a tissue is important for the understanding of oxygen delivery.
  
  
  METHODS
  A technique was developed to measure in a continuous manner the partial pressure of oxygen (pO2) in the optic nerve microvasculature of the minipig. This technique is based on the quenching by oxygen of the phosphorescence emitted by a dye that is injected intravenously. It provides measurements of the intra-vascular pO2 and was applied simultaneously with measurements of the extra-vascular pO2 with microelectrodes and blood flow by laser Doppler flowmetry.
  
  
  RESULTS
  We demonstrate for the first that the optic nerve head intra-vascular pO2 increases during dark adaptation. Furthermore no change in extra-vascular pO2 and blood flow could be detected.
  
  
  CONCLUSIONS
  Based on Krogh's model, these results suggest that oxygen consumption by the optic nerve head tissue increases during dark adaptation.
authors.affiliation: Institut de Recherches en Ophtalmologie, Sion.
authors.forename: S D
authors.initials: SD
authors.lastname: Cranstoun
authors.forename: C E
authors.initials: CE
authors.lastname: Riva
authors.forename: J L
authors.initials: JL
authors.lastname: Munoz
authors.forename: C J
authors.initials: CJ
authors.lastname: Pournaras
mesh_terms: D000818:Animals; D008665:Metalloporphyrins; D008833:Microcirculation / Q000502:physiology; D009898:Optic Disk / Q000098:blood supply*; D010092:Oximetry / Q000295:instrumentation*; D010101:Oxygen Consumption / Q000502:physiology*; D013552:Swine; D013556:Swine, Miniature
chemical_list: D008665:Metalloporphyrins