Measurement of renal tissue oxygen tension: systematic differences between fluorescence optode and microelectrode recordings in anaesthetized rabbits.
OBJECTIVE
The validity of fluorescence optodes for measurement of renal cortical tissue oxygen tension was tested by comparison with Clark electrodes.


METHODS
We varied renal blood flow and inspired O2 content in anaesthetized rabbits while simultaneously measuring cortical tissue oxygen tension.


RESULTS
Cortical oxygen tension varied with inspired O2 content. Fluorescence optode measurements were more tightly distributed than those from a Clark electrode. Cumulative frequency distributions for fluorescence optodes were shifted to the left of those for Clark electrodes. The slope of the relationship between oxygen tension in arterial blood and cortical tissue was less for the fluorescence optode than the Clark electrode. Cortical tissue oxygen tension measurements by these two methods were correlated (r(2) = 0.32; p < 0.001), with no fixed bias but considerable proportional bias. Thus, the slope of the relationship between the two measurements was less than unity (0.57 [0.50-0.69]).


CONCLUSIONS
Cortical oxygen tension values from fluorescence optodes are less variable but proportionally less than those from Clark electrodes. Theoretical considerations suggest that true interstitial oxygen tension lies somewhere between values provided by the two techniques. Nevertheless, the lesser variability of the fluorescence optode technique may aid detection of physiologically significant changes in intrarenal oxygenation.
Leong
Chai-Ling
CL
Department of Physiology, Monash University, Melbourne, Vic., Australia.
O'Connor
Paul M
PM
Eppel
Gabriela A
GA
Anderson
Warwick P
WP
Evans
Roger G
RG
D000109:Acetylcholine / Q000494:pharmacology; D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D005336:Fiber Optic Technology / Q000295:instrumentation*; D005453:Fluorescence; D007672:Kidney Cortex / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008839:Microelectrodes; D010092:Oximetry / Q000295:instrumentation*; D010100:Oxygen / Q000097:blood / Q000378:metabolism*; D010313:Partial Pressure; D011817:Rabbits; D012079:Renal Circulation / Q000187:drug effects; D015203:Reproducibility of Results; D013997:Time Factors; D014662:Vasoconstrictor Agents / Q000378:metabolism; D014665:Vasodilator Agents / Q000494:pharmacology
D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D000804:Angiotensin II; D000109:Acetylcholine; D010100:Oxygen