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Abstract
PURPOSE OF REVIEW To fully exploit the concept of hemodynamic coherence in resuscitating critically ill one should preferably take into account information about the state of parenchymal cells. Monitoring of mitochondrial oxygen tension (mitoPO2) has emerged as a clinical means to assess information of oxygen delivery and oxygen utilization at the mitochondrial level. This review will outline the basics of the technique, summarize its development and describe the rationale of measuring oxygen at the mitochondrial level. RECENT FINDINGS Mitochondrial oxygen tension can be measured by means of the protoporphyrin IX-Triplet State Lifetime Technique (PpIX-TSLT). After validation and use in preclinical animal models, the technique has recently become commercially available in the form of a clinical measuring system. This system has now been used in a number of healthy volunteer studies and is currently being evaluated in studies in perioperative and intensive care patients in several European university hospitals. SUMMARY PpIX-TSLT is a noninvasive and well tolerated method to assess aspects of mitochondrial function at the bedside. It allows doctors to look beyond the macrocirculation and microcirculation and to take the oxygen balance at the cellular level into account in treatment strategies.
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Non-invasive versus ex vivo measurement of mitochondrial function in an endotoxemia model in rat: Toward monitoring of mitochondrial therapy. Mitochondrion 2020; 50:149-157. [DOI: 10.1016/j.mito.2019.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 09/19/2019] [Accepted: 11/01/2019] [Indexed: 02/02/2023]
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Guerci P, Ince Y, Heeman P, Faber D, Ergin B, Ince C. A LED-based phosphorimeter for measurement of microcirculatory oxygen pressure. J Appl Physiol (1985) 2017; 122:307-316. [DOI: 10.1152/japplphysiol.00316.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 11/17/2016] [Accepted: 12/01/2016] [Indexed: 01/09/2023] Open
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 Po2 distributed over an organ or capillaries, to measuring microcirculatory Po2 changes 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 Po2 readings 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 Po2 in a rat subjected to hypoxic ventilation conditions and ischemia/reperfusion. The benefits of using LEDs as a light excitation source are presented.
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Affiliation(s)
- Philippe Guerci
- Department of Translational Physiology, Academic Medical Center, Amsterdam, The Netherlands
- INSERM U1116, Faculty of Medicine, University of Lorraine, Nancy, France
| | - Yasin Ince
- Department of Translational Physiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Paul Heeman
- Department of Medical Technical Innovation & Development (MIO), Academic Medical Center, Amsterdam, The Netherlands; and
| | - Dirk Faber
- Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, The Netherlands
| | - Bulent Ergin
- Department of Translational Physiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Can Ince
- Department of Translational Physiology, Academic Medical Center, Amsterdam, The Netherlands
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In Reply. Anesthesiology 2017; 126:349-350. [PMID: 28098613 DOI: 10.1097/aln.0000000000001438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ubbink R, Bettink MAW, Janse R, Harms FA, Johannes T, Münker FM, Mik EG. A monitor for Cellular Oxygen METabolism (COMET): monitoring tissue oxygenation at the mitochondrial level. J Clin Monit Comput 2016; 31:1143-1150. [PMID: 28000040 PMCID: PMC5655595 DOI: 10.1007/s10877-016-9966-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 12/08/2016] [Indexed: 12/31/2022]
Abstract
After introduction of the protoporphyrin IX-triplet state lifetime technique as a new method to measure mitochondrial oxygen tension in vivo, the development of a clinical monitor was started. This monitor is the "COMET", an acronym for Cellular Oxygen METabolism. The COMET is a non-invasive electrically powered optical device that allows measurements on the skin. The COMET is easy to transport, due to its lightweight and compact size. After 5-aminolevulinic acid application on the human skin, a biocompatible sensor enables detection of PpIX in the mitochondria. PpIX acts as a mitochondrially located oxygen-sensitive dye. Three measurement types are available in the touchscreen-integrated user interface, 'Single', 'Interval' and 'Dynamic measurement'. COMET is currently used in several clinical studies in our institution. In this first description of the COMET device we show an incidental finding during neurosurgery. To treat persisting intraoperative hypertension a patient was administered clonidine, but due to rapid administration an initial phase of peripheral vasoconstriction occurred. Microvascular flow and velocity parameters measured with laser-doppler (O2C, LEA Medizintechnik) decreased by 44 and 16% respectively, but not the venous-capillary oxygen saturation. However, mitochondrial oxygen tension in the skin detected by COMET decreased from a steady state of 48 to 16 mmHg along with the decrease in flow and velocity. We conclude that COMET is ready for clinical application and we see the future for this bedside monitor on the intensive care, operating theater, and testing of mitochondrial effect of pharmaceuticals.
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Affiliation(s)
- Rinse Ubbink
- Department of Anesthesiology, Laboratory for Experimental Anesthesiology, Erasmus MC - University Medical Center Rotterdam, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
| | - Mark A Wefers Bettink
- Department of Anesthesiology, Laboratory for Experimental Anesthesiology, Erasmus MC - University Medical Center Rotterdam, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
| | - Rineke Janse
- Department of Anesthesiology, Laboratory for Experimental Anesthesiology, Erasmus MC - University Medical Center Rotterdam, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
| | - Floor A Harms
- Department of Anesthesiology, Laboratory for Experimental Anesthesiology, Erasmus MC - University Medical Center Rotterdam, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
| | - Tanja Johannes
- Department of Anesthesiology, Laboratory for Experimental Anesthesiology, Erasmus MC - University Medical Center Rotterdam, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
| | | | - Egbert G Mik
- Department of Anesthesiology, Laboratory for Experimental Anesthesiology, Erasmus MC - University Medical Center Rotterdam, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands.
- Department of Intensive Care, Erasmus MC - University Medical Center Rotterdam, Rotterdam, The Netherlands.
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Harms F, Stolker RJ, Mik E. Cutaneous Respirometry as Novel Technique to Monitor Mitochondrial Function: A Feasibility Study in Healthy Volunteers. PLoS One 2016; 11:e0159544. [PMID: 27455073 PMCID: PMC4959702 DOI: 10.1371/journal.pone.0159544] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 07/04/2016] [Indexed: 01/16/2023] Open
Abstract
Background The protoporphyrin IX-triplet state lifetime technique (PpIX-TSLT) is proposed as a potential clinical non-invasive tool to monitor mitochondrial function. This technique has been evaluated in several animal studies. Mitochondrial respirometry allows measurement in vivo of mitochondrial oxygen tension (mitoPO2) and mitochondrial oxygen consumption (mitoVO2) in skin. This study describes the first use of a clinical prototype in skin of humans. Methods The clinical prototype was tested in 30 healthy volunteers. A self-adhesive patch containing 2 mg 5-aminolevulinic acid (ALA) was applied on the skin of the anterior chest wall (sternal) for induction of mitochondrial protoporphyrin IX and was protected from light for 5 h. MitoPO2 was measured by means of oxygen-dependent delayed fluorescence of protoporphyrin IX. MitoVO2 was determined by dynamic mitoPO2 measurements on the primed skin, while locally blocking oxygen supply by applying local pressure with the measurement probe. MitoPO2 was recorded before and during a 60-s period of compression of the microcirculation, at an interval of 1 Hz. Oxygen consumption (i.e. the local oxygen disappearance rate) was calculated from the decay of the mitoPO2 slope. Results Oxygen-dependent delayed fluorescence measurements were successfully performed in the skin of 27 volunteers. The average value (± SD) of mitoPO2 was 44 ± 17 mmHg and mean mitoVO2 values were 5.8 ± 2.3 and 6.1 ± 1.6 mmHg s-1 at a skin temperature of 34°C and 40°C, respectively. No major discomfort during measurement and no long-term dermatological abnormalities were reported in a survey performed 1 month after measurements. Conclusion These results show that the clinical prototype allows measurement of mitochondrial oxygenation and oxygen consumption in humans. The development of this clinically applicable device offers opportunities for further evaluation of the technique in humans and the start of first clinical studies.
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Affiliation(s)
- Floor Harms
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus University Medical Center Rotterdam, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
- * E-mail:
| | - Robert Jan Stolker
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus University Medical Center Rotterdam, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
| | - Egbert Mik
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus University Medical Center Rotterdam, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
- Department of Intensive Care, Erasmus University Medical Center Rotterdam, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
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Ince C, Mik EG. Microcirculatory and mitochondrial hypoxia in sepsis, shock, and resuscitation. J Appl Physiol (1985) 2016; 120:226-35. [DOI: 10.1152/japplphysiol.00298.2015] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 06/05/2015] [Indexed: 12/23/2022] Open
Abstract
After shock, persistent oxygen extraction deficit despite the apparent adequate recovery of systemic hemodynamic and oxygen-derived variables has been a source of uncertainty and controversy. Dysfunction of oxygen transport pathways during intensive care underlies the sequelae that lead to organ failure, and the limitations of techniques used to measure tissue oxygenation in vivo have contributed to the lack of progress in this area. Novel techniques have provided detailed quantitative insight into the determinants of microcirculatory and mitochondrial oxygenation. These techniques, which are based on the oxygen-dependent quenching of phosphorescence or delayed luminescence are briefly reviewed. The application of these techniques to animal models of shock and resuscitation revealed the heterogeneous nature of oxygen distributions and the alterations in oxygen distribution in the microcirculation and in mitochondria. These studies identified functional shunting in the microcirculation as an underlying cause of oxygen extraction deficit observed in states of shock and resuscitation. The translation of these concepts to the bedside has been enabled by our development and clinical introduction of hand-held microscopy. This tool facilitates the direct observation of the microcirculation and its alterations at the bedside under the conditions of shock and resuscitation. Studies identified loss of coherence between the macrocirculation and the microcirculation, in which resuscitation successfully restored systemic circulation but did not alleviate microcirculatory perfusion alterations. Various mechanisms responsible for these alterations underlie the loss of hemodynamic coherence during unsuccessful resuscitation procedures. Therapeutic resolution of persistent heterogeneous microcirculatory alterations is expected to improve outcomes in critically ill patients.
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Affiliation(s)
- Can Ince
- Department of Intensive Care, Erasmus MC, University Medical Center, Rotterdam
- Department of Translational Physiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Egbert G. Mik
- Department of Intensive Care, Erasmus MC, University Medical Center, Rotterdam
- Department of Anesthesiology, Erasmus MC, University Medical Center, Rotterdam; and
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Balestra GM, Aalders MCG, Specht PAC, Ince C, Mik EG. Oxygenation measurement by multi-wavelength oxygen-dependent phosphorescence and delayed fluorescence: catchment depth and application in intact heart. JOURNAL OF BIOPHOTONICS 2015; 8:615-628. [PMID: 25250821 DOI: 10.1002/jbio.201400054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 07/11/2014] [Accepted: 08/18/2014] [Indexed: 06/03/2023]
Abstract
Oxygen delivery and metabolism represent key factors for organ function in health and disease. We describe the optical key characteristics of a technique to comprehensively measure oxygen tension (PO(2)) in myocardium, using oxygen-dependent quenching of phosphorescence and delayed fluorescence of porphyrins, by means of Monte Carlo simulations and ex vivo experiments. Oxyphor G2 (microvascular PO(2)) was excited at 442 nm and 632 nm and protoporphyrin IX (mitochondrial PO(2)) at 510 nm. This resulted in catchment depths of 161 (86) µm, 350 (307) µm and 262 (255) µm respectively, as estimated by Monte Carlo simulations and ex vivo experiments (brackets). The feasibility to detect changes in oxygenation within separate anatomical compartments is demonstrated in rat heart in vivo. Schematic of ex vivo measurements.
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Affiliation(s)
- Gianmarco M Balestra
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus MC - University Medical Center Rotterdam, Rotterdam, The Netherlands
- Department of Medical Intensive Care, University Hospital Basel, Switzerland
- Department of Translational Physiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Maurice C G Aalders
- Department of Biomedical Engineering and Physics, Academic Medical Center, Amsterdam, The Netherlands
| | - Patricia A C Specht
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus MC - University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Can Ince
- Department of Translational Physiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Egbert G Mik
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus MC - University Medical Center Rotterdam, Rotterdam, The Netherlands
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10
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Cutaneous respirometry by dynamic measurement of mitochondrial oxygen tension for monitoring mitochondrial function in vivo. Mitochondrion 2013; 13:507-14. [DOI: 10.1016/j.mito.2012.10.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 09/19/2012] [Accepted: 10/02/2012] [Indexed: 11/23/2022]
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Harms FA, de Boon WMI, Balestra GM, Bodmer SIA, Johannes T, Stolker RJ, Mik EG. Oxygen-dependent delayed fluorescence measured in skin after topical application of 5-aminolevulinic acid. JOURNAL OF BIOPHOTONICS 2011; 4:731-739. [PMID: 21770036 DOI: 10.1002/jbio.201100040] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 06/26/2011] [Accepted: 06/27/2011] [Indexed: 05/31/2023]
Abstract
Mitochondrial oxygen tension can be measured in vivo by means of oxygen-dependent quenching of delayed fluorescence of protoporphyrin IX (PpIX). Here we demonstrate that delayed fluorescence is readily observed from skin in rat and man after topical application of the PpIX precursor 5-aminolevulinic acid (ALA). Delayed fluorescence lifetimes respond to changes in inspired oxygen fraction and blood supply. The signals contain lifetime distributions and the fitting of rectangular distributions to the data appears more adequate than mono-exponential fitting. The use of topically applied ALA for delayed fluorescence lifetime measurements might pave the way for clinical use of this technique.
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Affiliation(s)
- Floor A Harms
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, ErasmusMC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Piffaretti F, Santhakumar K, Forte E, van den Bergh HE, Wagnières GA. Optical fiber-based setup for in vivo measurement of the delayed fluorescence lifetime of oxygen sensors. JOURNAL OF BIOMEDICAL OPTICS 2011; 16:037005. [PMID: 21456878 DOI: 10.1117/1.3558846] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A new optical-fiber-based spectrofluorometer for in vivo or in vitro detection of delayed fluorescence is presented and characterized. This compact setup is designed so that it can be readily adapted for future clinical use. Optical excitation is done with a nitrogen laser-pumped, tunable dye laser, emitting in the UV-vis part of the spectrum. Excitation and luminescence signals are carried to and from the biological tissues under investigation, located out of the setup enclosure, by a single optical fiber. These measurements, as well as measurements performed without a fiber on in vitro samples in a thermostable quartz cell, in a controlled-atmosphere enclosure, are possible due to the efficient collection of the laser-induced luminescence light which is collected and focused on the detector with a high aperture parabolic mirror. The detection is based on a gated photomultiplier which allows for time-resolved measurements of the delayed fluorescence intensity. Thus, relevant luminescence lifetimes, typically in the sub-microsecond-to-millisecond range, can be measured with near total rejection of the sample's prompt fluorescence. The instrument spectral and temporal resolution, as well as its sensitivity, is characterized and measurement examples are presented. The primary application foreseen for this setup is the monitoring and adjustment of the light dose delivered during photodynamic therapy.
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Iloprost preserves renal oxygenation and restores kidney function in endotoxemia-related acute renal failure in the rat. Crit Care Med 2009; 37:1423-32. [DOI: 10.1097/ccm.0b013e31819b5f4e] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Mitochondrial oxygen tension within the heart. J Mol Cell Cardiol 2009; 46:943-51. [PMID: 19232352 DOI: 10.1016/j.yjmcc.2009.02.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Revised: 02/04/2009] [Accepted: 02/04/2009] [Indexed: 01/09/2023]
Abstract
By using a newly developed optical technique which enables non-invasive measurement of mitochondrial oxygenation (mitoPO(2)) in the intact heart, we addressed three long-standing oxygenation questions in cardiac physiology: 1) what is mitoPO(2) within the in vivo heart?, 2) is mitoPO(2) heterogeneously distributed?, and 3) how does mitoPO(2) of the isolated Langendorff-perfused heart compare with that in the in vivo working heart? Following calibration and validation studies of the optical technique in isolated cardiomyocytes, mitochondria and intact hearts, we show that in the in vivo condition mean mitoPO(2) was 35+/-5 mm Hg. The mitoPO(2) was highly heterogeneous, with the largest fraction (26%) of mitochondria having a mitoPO(2) between 10 and 20 mm Hg, and 10% between 0 and 10 mm Hg. Hypoxic ventilation (10% oxygen) increased the fraction of mitochondria in the 0-10 mm Hg range to 45%, whereas hyperoxic ventilation (100% oxygen) had no major effect on mitoPO(2). For Langendorff-perfused rat hearts, mean mitoPO(2) was 29+/-5 mm Hg with the largest fraction of mitochondria (30%) having a mitoPO(2) between 0 and 10 mm Hg. Only in the maximally vasodilated condition, did the isolated heart compare with the in vivo heart (11% of mitochondria between 0 and 10 mm Hg). These data indicate 1) that the mean oxygen tension at the level of the mitochondria within the heart in vivo is higher than generally considered, 2) that mitoPO(2) is considerably heterogeneous, and 3) that mitoPO(2) of the classic buffer-perfused Langendorff heart is shifted to lower values as compared to the in vivo heart.
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In vivo mitochondrial oxygen tension measured by a delayed fluorescence lifetime technique. Biophys J 2008; 95:3977-90. [PMID: 18641065 DOI: 10.1529/biophysj.107.126094] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Mitochondrial oxygen tension (mitoPO(2)) is a key parameter for cellular function, which is considered to be affected under various pathophysiological circumstances. Although many techniques for assessing in vivo oxygenation are available, no technique for measuring mitoPO(2) in vivo exists. Here we report in vivo measurement of mitoPO(2) and the recovery of mitoPO(2) histograms in rat liver by a novel optical technique under normal and pathological circumstances. The technique is based on oxygen-dependent quenching of the delayed fluorescence lifetime of protoporphyrin IX. Application of 5-aminolevulinic acid enhanced mitochondrial protoporphyrin IX levels and induced oxygen-dependent delayed fluorescence in various tissues, without affecting mitochondrial respiration. Using fluorescence microscopy, we demonstrate in isolated hepatocytes that the signal is of mitochondrial origin. The delayed fluorescence lifetime was calibrated in isolated hepatocytes and isolated perfused livers. Ultimately, the technique was applied to measure mitoPO(2) in rat liver in vivo. The results demonstrate mitoPO(2) values of approximately 30-40 mmHg. mitoPO(2) was highly sensitive to small changes in inspired oxygen concentration around atmospheric oxygen level. Ischemia-reperfusion interventions showed altered mitoPO(2) distribution, which flattened overall compared to baseline conditions. The reported technology is scalable from microscopic to macroscopic applications, and its reliance on an endogenous compound greatly enhances its potential field of applications.
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Levosimendan but not norepinephrine improves microvascular oxygenation during experimental septic shock. Crit Care Med 2008; 36:1886-91. [DOI: 10.1097/ccm.0b013e31817cede9] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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17
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Mik EG, Johannes T, Ince C. Monitoring of renal venous PO2 and kidney oxygen consumption in rats by a near-infrared phosphorescence lifetime technique. Am J Physiol Renal Physiol 2008; 294:F676-81. [PMID: 18184739 DOI: 10.1152/ajprenal.00569.2007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Renal oxygen consumption (Vo(2,ren)) is an important parameter that has been shown to be influenced by various pathophysiological circumstances. Vo(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 Po(2) (vPo(2)) and Vo(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 Po(2) and hemoglobin saturation. To demonstrate its feasibility in practice, the technique was used in four rats during endotoxin infusion (10 mg x kg(-1) x h(-1) during 1 h). Renal vPo(2) reduced by 40% upon reduction in oxygen delivery to 30% of baseline, but Vo(2) remained unchanged. This study documents the feasibility of near-continuous, nondestructive measurement of renal vPo(2) and Vo(2) by oxygen-dependent quenching of phosphorescence.
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Affiliation(s)
- Egbert G Mik
- Department of Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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18
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Mik EG, Stap J, Sinaasappel M, Beek JF, Aten JA, van Leeuwen TG, Ince C. Mitochondrial PO2 measured by delayed fluorescence of endogenous protoporphyrin IX. Nat Methods 2006; 3:939-45. [PMID: 17060918 DOI: 10.1038/nmeth940] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Accepted: 08/10/2006] [Indexed: 11/09/2022]
Abstract
Molecular oxygen is the primary oxidant in biological systems. The ultimate destination of oxygen in vivo is the mitochondria where it is used in oxidative phosphorylation. The ability of this process to produce an amount of high-energy phosphates adequate to sustain life highly depends on the available amount of oxygen. Despite a vast array of techniques to measure oxygen, major (patho)physiological questions remain unanswered because of the unavailability of quantitative techniques to measure mitochondrial oxygen in situ. Here we demonstrate that mitochondrial PO(2) can be directly measured in living cells by harnessing the delayed fluorescence of endogenous protoporphyrin IX (PpIX), thereby providing a technique with the potential for a wide variety of applications. We applied this technique to different cell lines (V-79 Chinese hamster lung fibroblasts, HeLa cells and IMR 32-K1 neuroblastoma cells) and present the first direct measurements of the oxygen gradient between the mitochondria and the extracellular volume.
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Affiliation(s)
- Egbert G Mik
- Department of Physiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
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Chandler DE, Majumdar ZK, Heiss GJ, Clegg RM. Ruby crystal for demonstrating time- and frequency-domain methods of fluorescence lifetime measurements. J Fluoresc 2006; 16:793-807. [PMID: 17031574 DOI: 10.1007/s10895-006-0123-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Accepted: 08/09/2006] [Indexed: 10/24/2022]
Abstract
We present experiments that are convenient and educational for measuring fluorescence lifetimes with both time- and frequency-domain methods. The sample is ruby crystal, which has a lifetime of about 3.5 milliseconds, and is easy to use as a class-room demonstration. The experiments and methods of data analysis are used in the lab section of a class on optical spectroscopy, where we go through the theory and applications of fluorescence. Because the fluorescence decay time of ruby is in the millisecond region, the instrumentation for this experiment can be constructed easily and inexpensively compared to the nanosecond-resolved instrumentation required for most fluorescent compounds, which have nanosecond fluorescence lifetimes. The methods are applicable to other luminescent compounds with decay constants from microseconds and longer, such as transition metal and lanthanide complexes and phosphorescent samples. The experiments, which clearly demonstrate the theory and methods of measuring temporally resolved fluorescence, are instructive and demonstrate what the students have learned in the lectures without the distraction of highly sophisticated instrumentation.
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Affiliation(s)
- Danielle E Chandler
- Physics Department, University of Illinois Urbana-Champaign, 1110 West Green Street, Urbana, IL 61801, USA
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Johannes T, Mik EG, Ince C. Dual-wavelength phosphorimetry for determination of cortical and subcortical microvascular oxygenation in rat kidney. J Appl Physiol (1985) 2005; 100:1301-10. [PMID: 16357065 DOI: 10.1152/japplphysiol.01315.2005] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
This study presents a dual-wavelength phosphorimeter developed to measure microvascular PO2 (microPO2) in different depths in tissue and demonstrates its use in rat kidney. The used phosphorescent dye is Oxyphor G2 with excitation bands at 440 and 632 nm. The broad spectral gap between the excitation bands combined with a relatively low light absorption of 632 nm light by tissue results in a marked difference in penetration depths of both excitation wavelengths. In rat kidney, we determine the catchments depth of the 440-nm excitation to be 700 microm, whereas the catchments depth of 632 nm is as much as 4 mm. Therefore, the measurements differentiate between cortex and outer medulla, respectively. In vitro, no difference in PO2 readings between both channels was found. On the rat kidney in vivo, the measured cortical microPO2 was on average 20 Torr higher than the medullary microPO2 over a wide PO2 range induced by variations in inspired oxygen fraction. Examples provided from endotoxemia and resuscitation show differences in responses of mean cortical and medullary PO2 readings as well as in the shape of the PO2 histograms. It can be concluded that oxygen-dependent quenching of phosphorescence of Oxyphor G2 allows quantitative measurement of microPO2 noninvasively in two different depths in vivo. Oxygen levels measured by this technique in the rat renal cortex and outer medulla are consistent with previously published values detected by Clark-type oxygen electrodes. Dual-wavelength phosphorimetry is excellently suited for monitoring microPO2 changes in two different anatomical layers under pathophysiological conditions with the characteristics of providing oxygen histograms from two depths and having a penetration depth of several millimeters.
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Affiliation(s)
- Tanja Johannes
- Department of Physiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
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Schwarte LA, Fournell A, van Bommel J, Ince C. Redistribution of intestinal microcirculatory oxygenation during acute hemodilution in pigs. J Appl Physiol (1985) 2005; 98:1070-5. [PMID: 15475597 DOI: 10.1152/japplphysiol.00861.2004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acute normovolemic hemodilution (ANH) compromizes intestinal microcirculatory oxygenation; however, the underlying mechanisms are incompletely understood. We hypothesized that contributors herein include redistribution of oxygen away from the intestines and shunting of oxygen within the intestines. The latter may be due to the impaired ability of erythrocytes to off-load oxygen within the microcirculation, thus yielding low tissue/plasma Po2 but elevated microcirculatory hemoglobin oxygen (HbO2) saturations. Alternatively, oxygen shunting may also be due to reduced erythrocyte deformability, hindering the ability of erythrocytes to enter capillaries. Anesthetized pigs underwent ANH (20, 40, 60, and 90 ml/kg hydroxyethyl starch; ANH group: n = 10; controls: n = 5). We measured systemic and mesenteric perfusion. Microvascular intestinal oxygenation was measured independently by remission spectrophotometry [microcirculatory HbO2 saturation (μHbO2)] and palladium-porphyrin phosphorescence quenching [microcirculatory oxygen pressure in plasma/tissue (μPo2)]. Microcirculatory oxygen shunting was assessed as the disparity between mucosal and mesenteric venous HbO2 saturation (HbO2-gap). Erythrocyte deformability was measured as shear stress-induced cell elongation (LORCA difractometer). ANH reduced hemoglobin concentration from 8.1 to 2.2 g/dl. Relative mesenteric perfusion decreased (decreased mesenteric/systemic perfusion fraction). A paralleled reduction occurred in mucosal μHbO2 (68 ± 2 to 41 ± 3%) and μPo2 (28 ± 1 to 17 ± 1 Torr). Thus the proposed constellation indicative for oxygen off-load deficits (sustained μHbO2 at decreased μPo2) did not develop. A twofold increase in the HbO2-gap indicated increasing intestinal microcirculatory oxygen shunting. Significant impairment in erythrocyte deformability developed during ANH. We conclude that reduced intestinal oxygenation during ANH is, in addition to redistribution of oxygen delivery away from the intestines, associated with oxygen shunting within the intestines. This shunting appears to be not primarily caused by oxygen off-load deficit but rather by oxygen/erythrocytes bypassing capillaries, wherein a potential contributor is impaired erythrocyte deformability.
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Affiliation(s)
- Lothar A Schwarte
- Department of Physiology, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, 1105AZ, Amsterdam, The Netherlands
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Raat NJH, Liu JF, Doyle MP, Burhop KE, Klein J, Ince C. Effects of recombinant-hemoglobin solutions rHb2.0 and rHb1.1 on blood pressure, intestinal blood flow, and gut oxygenation in a rat model of hemorrhagic shock. ACTA ACUST UNITED AC 2005; 145:21-32. [PMID: 15668658 DOI: 10.1016/j.lab.2004.05.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The vasoconstriction induced by hemoglobin-based oxygen carriers (HBOCs), mainly a result of nitric oxide (NO) scavenging, until now has limited the application of HBOCs as resuscitation fluids. In this study, we tested the hypothesis that the new modified recombinant-hemoglobin solution rHb2.0, with a 20 to 30 times lesser NO-scavenging rate, would minimize vasoconstriction without adverse effects on microvascular oxygenation. Responses were compared with those to rHb1.1, a recombinant-hemoglobin solution with a wild-type NO-scavenging rate, as well as an oncotically matched albumin solution. In a fixed-pressure (40 mm Hg) rat model of hemorrhagic shock and resuscitation, rHb2.0 and albumin both restored mean arterial pressure (MAP) to baseline values, whereas rHb1.1 increased MAP to 27% above the baseline value. Mesenteric vascular resistance after resuscitation with rHb2.0 was 57% less than that with rHb1.1. rHb2.0 was found to have 55% greater intestinal oxygen delivery (Do2int ) and resulted in a 27% lower oxygen-extraction rate than did rHb1.1 after resuscitation. Intestinal microvascular Po2 , determined on the basis of oxygen-dependent quenching of palladium-porphyrin phosphorescence, revealed no difference between rHb2.0 and rHb1.1. The findings of this study confirm that the well-known pressure effect of HBOCs is caused by their effect on the NO-scavenging rate; recombinant modification of this rate did not increase MAP during resuscitation compared with baseline values. Although systemic vasoconstriction was absent, intestinal vasoconstriction almost negligible, and Do2int greater after resuscitation with rHb2.0, the effect of rHb2.0 on pH, base-excess and microvascular Po2 levels after resuscitation were comparable to those achieved with the use of the albumin solution.
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Affiliation(s)
- Nicolaas J H Raat
- Department of Physiology, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
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Mik EG, van Leeuwen TG, Raat NJ, Ince C. Quantitative determination of localized tissue oxygen concentration in vivo by two-photon excitation phosphorescence lifetime measurements. J Appl Physiol (1985) 2004; 97:1962-9. [PMID: 15247164 DOI: 10.1152/japplphysiol.01399.2003] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
This study describes the use of two-photon excitation phosphorescence lifetime measurements for quantitative oxygen determination in vivo. Doubling the excitation wavelength of Pd-porphyrin from visible light to the infrared allows for deeper tissue penetration and a more precise and confined selection of the excitation volume due to the nonlinear two-photon effect. By using a focused laser beam from a 1,064-nm Q-switched laser, providing 10-ns pulses of 10 mJ, albumin-bound Pd-porphyrin was effectively excited and oxygen-dependent decay of phosphorescence was observed. In vitro calibration of phosphorescence lifetime vs. oxygen tension was performed. The obtained calibration constants were kq = 356 Torr(-1) x s(-1) (quenching constant) and tau0 = 550 micros (lifetime at zero-oxygen conditions) at 37 degrees C. The phosphorescence intensity showed a squared dependency to the excitation intensity, typical for two-photon excitation. In vivo demonstration of two-photon excitation phosphorescence lifetime measurements is shown by step-wise PO2 measurements through the cortex of rat kidney. It is concluded that quantitative oxygen measurements can be made, both in vitro and in vivo, using two-photon excitation oxygen-dependent quenching of phosphorescence. The use of two-photon excitation has the potential to lead to new applications of the phosphorescence lifetime technique, e.g., noninvasive oxygen scanning in tissue at high spatial resolution. To our knowledge, this is the first report in which two-photon excitation is used in the setting of oxygen-dependent quenching of phosphorescence lifetime measurements.
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Affiliation(s)
- Egbert G Mik
- Department of Physiology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
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