title: A LED-based phosphorimeter for measurement of microcirculatory oxygen pressure.
abstract: Quantitative measurements of microcirculatory and tissue oxygenation are of prime importance in experimental research. The noninvasive phosphorescence quenching method has given further insight into the fundamental mechanisms of oxygen transport to healthy tissues and in models of disease. Phosphorimeters are devices dedicated to the study of phosphorescence quenching. The experimental applications of phosphorimeters range from measuring a specific oxygen partial pressure (Po2) in cellular organelles such as mitochondria, finding values of Po2distributed over an organ or capillaries, to measuring microcirculatory Po2changes simultaneously in several organ systems. Most of the current phosphorimeters use flash lamps as a light excitation source. However, a major drawback of flash lamps is their inherent plasma glow that persists for tens of microseconds after the primary discharge. This complex distributed excitation pattern generated by the flash lamp can lead to inaccurate Po2readings unless a deconvolution analysis is performed. Using light-emitting diode (LED), a rectangular shaped light pulse can be generated that provides a more uniformly distributed excitation signal. This study presents the design and calibration process of an LED-based phosphorimeter (LED-P). The in vitro calibration of the LED-P using palladium(II)-meso-tetra(4-carboxyphenyl)-porphyrin (Pd-TCCP) as a phosphorescent dye is presented. The pH and temperature were altered to assess whether the decay times of the Pd-TCCP measured by the LED-P were significantly influenced. An in vivo validation experiment was undertaken to measure renal cortical Po2in a rat subjected to hypoxic ventilation conditions and ischemia/reperfusion. The benefits of using LEDs as a light excitation source are presented.
authors.affiliation: Department of Translational Physiology, Academic Medical Center, Amsterdam, The Netherlands; phil.guerci@gmail.com.|INSERM U1116, Faculty of Medicine, University of Lorraine, Nancy, France.
authors.forename: Philippe
authors.identifier: http://orcid.org/0000-0002-4664-1861
authors.initials: P
authors.lastname: Guerci
authors.affiliation: Department of Translational Physiology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Yasin
authors.initials: Y
authors.lastname: Ince
authors.affiliation: Department of Medical Technical Innovation & Development (MIO), Academic Medical Center, Amsterdam, The Netherlands; and.
authors.forename: Paul
authors.initials: P
authors.lastname: Heeman
authors.affiliation: Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Dirk
authors.initials: D
authors.lastname: Faber
authors.affiliation: Department of Translational Physiology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Bulent
authors.initials: B
authors.lastname: Ergin
authors.affiliation: Department of Translational Physiology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Can
authors.initials: C
authors.lastname: Ince
mesh_terms: D000818:Animals; D002138:Calibration; D002196:Capillaries / Q000378:metabolism / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D008027:Light; D008163:Luminescent Measurements / Q000379:methods; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D010313:Partial Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D013696:Temperature
chemical_list: D010100:Oxygen
keywords: LED; measurement; oxygen phosphorimeter