title: Microvascular and mitochondrial PO(2)  simultaneously measured by oxygen-dependent delayed luminescence.
abstract: Measurement of tissue oxygenation is a complex task and various techniques have led to a wide range of tissue PO(2) values and contradictory results. Tissue is compartmentalized in microcirculation, interstitium and intracellular space and current techniques are biased towards a certain compartment. Simultaneous oxygen measurements in various compartments might be of great benefit for our understanding of determinants of tissue oxygenation. Here we report simultaneous measurement of microvascular PO(2) (μPO(2) ) and mitochondrial PO(2) (mitoPO(2) ) in rats. The μPO(2) measurements are based on oxygen-dependent quenching of phosphorescence of the near-infrared phosphor Oxyphor G2. The mitoPO(2) measurements are based on oxygen-dependent quenching of delayed fluorescence of protoporphyrin IX (PpIX). Favorable spectral properties of these porphyrins allow simultaneous measurement of the delayed luminescence lifetimes. A dedicated fiber-based time-domain setup consisting of a tunable pulsed laser, 2 red-sensitive gated photomultiplier tubes and a simultaneous sampling data-acquisition system is described in detail. The absence of cross talk between the channels is shown and the feasibility of simultaneous μPO(2) and mitoPO(2) measurements is demonstrated in rat liver in vivo. It is anticipated that this novel approach will greatly contribute to our understanding of tissue oxygenation in physiological and pathological circumstances.
authors: Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus MC - University Medical Center Rotterdam, s-Gravendijkwal 230, 3015 CE, Rotterdam, The Netherlands.
authors: Sander I A
authors: SI
authors: Bodmer
authors: Gianmarco M
authors: GM
authors: Balestra
authors: Floor A
authors: FA
authors: Harms
authors: Tanja
authors: T
authors: Johannes
authors: Nicolaas J H
authors: NJ
authors: Raat
authors: Robert J
authors: RJ
authors: Stolker
authors: Egbert G
authors: EG
authors: Mik
mesh_terms: D000818:Animals; D007834:Lasers; D008099:Liver / Q000378:metabolism; D049449:Luminescence; D008665:Metalloporphyrins / Q000737:chemistry; D008833:Microcirculation; D008928:Mitochondria / Q000378:metabolism*; D008954:Models, Biological; D010100:Oxygen / Q000737:chemistry; D010101:Oxygen Consumption; D010313:Partial Pressure; D010758:Phosphorus / Q000737:chemistry; D011166:Porphyrins / Q000737:chemistry; D011524:Protoporphyrins / Q000737:chemistry; D051381:Rats; D013053:Spectrophotometry / Q000379:methods*; D013997:Time Factors
chemical_list: D008665:Metalloporphyrins; D011166:Porphyrins; D011524:Protoporphyrins; C474536:oxyphor G2; D010758:Phosphorus; C028025:protoporphyrin IX; D010100:Oxygen