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This Article Full Text Full Text (PDF) All Versions of this Article: 294/3/F676    most recent 00569.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Mik, E. G. Articles by Ince, C. PubMed PubMed Citation Articles by Mik, E. G. Articles by Ince, C.

INNOVATIVE METHODOLOGY

Monitoring of renal venous PO₂ and kidney oxygen consumption in rats by a near-infrared phosphorescence lifetime technique

¹Department of Physiology, Academic Medical Center, University of Amsterdam, Amsterdam; ²Department of Anesthesiology, Erasmus Medical Center, University of Rotterdam, Rotterdam, The Netherlands; and ³Department of Anesthesiology and Critical Care, University Hospital Tuebingen, Tuebingen, Germany

Submitted 29 November 2007 ; accepted in final form 2 January 2008

Renal oxygen consumption (O_2,ren) is an important parameter that has been shown to be influenced by various pathophysiological circumstances. O_2,ren has to be repeatedly measured during an experiment to gain insight in the dynamics of (dys)regulation of oxygen metabolism. In small animals, the classical approach of blood gas analysis of arterial and venous blood samples is only limitedly applicable due to fragile vessels and a low circulating blood volume. We present a phosphorescence lifetime technique that allows near-continuous measurement of renal venous PO₂ (vPO₂) and O_2,ren in rats. The technique does not rely on penetration of the blood vessel, but uses a small reflection probe. This probe is placed in close proximity to the renal vein for detection of the oxygen-dependent phosphorescence of the injected water-soluble near-infrared phosphor Oxyphor G2. The technique was calibrated in vitro and the calibration constants were validated in vivo in anesthetized and mechanically ventilated male Wistar rats. The hemoglobin saturation curve and its pH dependency were determined for calculation of renal venous oxygen content. The phosphorescence technique was in good agreement with blood gas analysis of renal venous blood samples, for both PO₂ and hemoglobin saturation. To demonstrate its feasibility in practice, the technique was used in four rats during endotoxin infusion (10 mg·kg^–1·h^–1 during 1 h). Renal vPO₂ reduced by 40% upon reduction in oxygen delivery to 30% of baseline, but O₂ remained unchanged. This study documents the feasibility of near-continuous, nondestructive measurement of renal vPO₂ and O₂ by oxygen-dependent quenching of phosphorescence.

oxygen-dependent quenching; Oxyphor G2; time-resolved spectroscopy; Pd-porphyrin