Continuous measurements of intra-vascular pO2 in the pig optic nerve head.
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.
Cranstoun
S D
SD
Institut de Recherches en Ophtalmologie, Sion.
Riva
C E
CE
Munoz
J L
JL
Pournaras
C J
CJ
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
D008665:Metalloporphyrins