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Keeley TP, Mann GE. Defining Physiological Normoxia for Improved Translation of Cell Physiology to Animal Models and Humans. Physiol Rev 2019; 99:161-234. [PMID: 30354965 DOI: 10.1152/physrev.00041.2017] [Citation(s) in RCA: 179] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The extensive oxygen gradient between the air we breathe (Po2 ~21 kPa) and its ultimate distribution within mitochondria (as low as ~0.5-1 kPa) is testament to the efforts expended in limiting its inherent toxicity. It has long been recognized that cell culture undertaken under room air conditions falls short of replicating this protection in vitro. Despite this, difficulty in accurately determining the appropriate O2 levels in which to culture cells, coupled with a lack of the technology to replicate and maintain a physiological O2 environment in vitro, has hindered addressing this issue thus far. In this review, we aim to address the current understanding of tissue Po2 distribution in vivo and summarize the attempts made to replicate these conditions in vitro. The state-of-the-art techniques employed to accurately determine O2 levels, as well as the issues associated with reproducing physiological O2 levels in vitro, are also critically reviewed. We aim to provide the framework for researchers to undertake cell culture under O2 levels relevant to specific tissues and organs. We envisage that this review will facilitate a paradigm shift, enabling translation of findings under physiological conditions in vitro to disease pathology and the design of novel therapeutics.
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Affiliation(s)
- Thomas P Keeley
- King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London , London , United Kingdom
| | - Giovanni E Mann
- King's British Heart Foundation Centre of Research Excellence, School of Cardiovascular Medicine and Sciences, Faculty of Life Sciences and Medicine, King's College London , London , United Kingdom
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Abstract
Although it is generally believed that oxidative phosphorylation and adequate oxygenation are essential for life, human development occurs in a profoundly hypoxic environment and "normal" levels of oxygen during embryogenesis are even harmful. The ability of embryos not only to survive but also to thrive in such an environment is made possible by adaptations related to metabolic pathways. Similarly, cancerous cells are able not only to survive but also to grow and spread in environments that would typically be fatal for healthy adult cells. Many biological states, both normal and pathological, share underlying similarities related to metabolism, the electron transport chain, and reactive species. The purpose of Part I of this review is to review the similarities among embryogenesis, mammalian adaptions to hypoxia (primarily driven by hypoxia-inducible factor-1), ischemia-reperfusion injury (and its relationship with reactive oxygen species), hibernation, diving animals, cancer, and sepsis, with a particular focus on the common characteristics that allow cells and organisms to survive in these states.
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Affiliation(s)
- Robert H Thiele
- From the Department of Anesthesiology, University of Virginia, Charlottesville, VA
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Abstract
Useful resuscitation endpoints must serve both to diagnose the need for and to ensure the ongoing adequacy of resuscitation. To this end, traditional measures of organ perfusion are now widely appreciated to be grossly inadequate. Useful endpoints or milestones range from the global, to the regional, to the cellular specific. Understanding the basic principles of perfusion-related dysoxia in trauma and hemorrhage and its potential rapid transition to involve inflammatory and immune responses on cellular oxygen utilization will aid the clinician in choosing and appropriately interpreting endpoint monitoring data. There also appears to be an optimal window of opportunity for monitoring to help mitigate the development of more complicated inflammatory states. This article reviews the underlying need for endpoint selection (both global and regional, biochemical and functional) and monitoring during resuscitation of the polytrauma patient. At this juncture it appears that early use of a blend of global markers such as lactate and base deficit coupled with an available sensitive regional monitor such as gastric tonometry may offer the best combination of current technology to guard against early perfusion-related dysoxia. Future techniques involving optical spectroscopy offer the exciting potential to assess oxygenation at the cellular level. This may aid in ultra-early detection and resolution of perfusion-related dysoxia in addition to recognizing its transition to more complex inflammatory-mediated circulatory and metabolic failure.
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Affiliation(s)
- Kevin R. Ward
- Virginia Commonwealth University Reanimation Engineering and Shock Center (VCURES), Richmond, VA., Departments of Emergency Medicine and Physiology, Virginia Commonwealth University, Richmond, VA., Department of Surgery and Section of Trauma and Surgical Critical Care, Virginia Commonwealth University, Richmond, VA
| | - Rao R. Ivatury
- Virginia Commonwealth University Reanimation Engineering and Shock Center (VCURES), Richmond, VA., Departments of Emergency Medicine and Physiology, Virginia Commonwealth University, Richmond, VA., Department of Surgery and Section of Trauma and Surgical Critical Care, Virginia Commonwealth University, Richmond, VA
| | - R. Wayne Barbee
- Virginia Commonwealth University Reanimation Engineering and Shock Center (VCURES), Richmond, VA., Departments of Emergency Medicine and Physiology, Virginia Commonwealth University, Richmond, VA
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Bbeta15-42 (FX06) reduces pulmonary, myocardial, liver, and small intestine damage in a pig model of hemorrhagic shock and reperfusion. Crit Care Med 2009; 37:598-605. [PMID: 19114899 DOI: 10.1097/ccm.0b013e3181959a12] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The fibrin-derived peptide Bbeta15-42 (also called FX06) has been shown to reduce myocardial infarct size following ischemia/reperfusion. Hemorrhagic shock (HS) followed by volume resuscitation represents a similar scenario, whereby a whole organism is vulnerable to reperfusion injury. DESIGN We subjected male farm-bred landrace pigs ( approximately 30 kg) to HS by withdrawing blood to a mean arterial pressure of 40 mm Hg for 60 minutes. Pigs were then resuscitated with shed blood and crystalloids for 60 minutes, and at this time, FX06 (2.4 mg/kg, n = 8) or vehicle control (phosphate buffered saline; 2.4 mg/kg, n = 7) was injected as an intravenous bolus. SETTING University hospital laboratory. SUBJECTS Anesthetized male farm-bred landrace pigs. MEASUREMENTS AND MAIN RESULTS Data are presented as mean +/- sd. Five hours after resuscitation, controls presented acute lung injury (Pao2/Fio2-ratio <300 mm Hg; extra-vascular lung water index (marker for lung injury): 9.0 +/- 1.8 mL/kg) and myocardial dysfunction/damage (cardiac index: 4.3 +/- 0.25 L/min/m; stroke volume index: 30 +/- 6 mL/m; cardiac TnT levels: 0.58 +/- 0.25 ng/mL). In contrast, FX06-treated animals showed significantly improved pulmonary and circulatory function (Pao2/Fio2-ratio >*400 mm Hg; extra-vascular lung water index: *5.2 +/- 2.1 mL/kg, cardiac index: *6.3 +/- 1.4 L/min/m; stroke volume index: *51 +/- 11 mL/m; cardiac TnT levels: *0.11 +/- 0.09 ng/mL; *p < 0.05). Also, tissue oxygenation (tpO2; mm Hg) was significantly improved during reperfusion in FX06-treated pigs when compared with controls (liver 51 +/- 4 vs. *65 +/- 4; serosa 44 +/- 5 vs. *55 +/- 7; mucosa 14 +/- 4 vs. *26 +/- 4). Finally, FX06 reduced accumulation of myeloperoxidase-positive cells (mainly neutrophils) in myocardium, liver, and small intestine and reduced interleukin-6 plasma levels (*p < 0.05; compared with controls). CONCLUSION We conclude that in a pig model of HS and reperfusion, administration of FX06 during reperfusion protects shock- susceptible organs such as heart, lung, liver, and small intestine.
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Iber T, Roesner JP, Mutz C, Werner B, Peters E, Brüderlein K, Nöldge-Schomburg G, Vagts DA. Einfluss der Clonidin-induzierten systemischen Sympathikolyse auf die Oxygenierung und Perfusion der Leber. Anaesthesist 2007; 56:470-7. [PMID: 17370053 DOI: 10.1007/s00101-007-1165-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND Increased sympathetic nervous activity which induces vasoconstriction and decreases perfusion may be an underlying mechanism behind the development of perioperative liver damage. This animal study was designed to assess how clonidine-induced systemic sympathicolysis affects liver oxygenation with respect to induced hypotension and vasodilatation under physiological conditions. METHODS Following ethical approval 17 anesthetized and acutely instrumented pigs were randomly assigned to 2 groups. Group 1 consisted of 8 animals receiving intravenous clonidine (2 microg x kg(-1) bolus and 2 microg x kg(-1) x h(-1) for induction of sympathicolysis and group 2 consisted of 9 animals serving as controls. After obtaining baseline values, measurements were repeated 90 and 250 min after starting to reduce systemic sympathetic nervous activity. RESULTS Clonidine-induced systemic sympathicolysis was associated with decreased mean arterial blood pressure, cardiac output and heart rate. Portal venous and hepatic arterial blood flow, oxygen delivery to the liver, oxygen uptake and liver tissue oxygen partial pressure remained unchanged. The plasma indocyanine green disappearance rate increased. CONCLUSION We concluded that despite decreased mean arterial pressure and cardiac output, clonidine-induced systemic sympathicolysis did not affect liver oxygenation or perfusion.
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Affiliation(s)
- T Iber
- Klinik und Poliklinik für Anästhesiologie und Intensivtherapie, Universität Rostock, Schillingallee 35, 18055 Rostock, Deutschland
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Vagts DA, Iber T, Puccini M, Szabo B, Haberstroh J, Villinger F, Geiger K, Nöldge-Schomburg GFE. The effects of thoracic epidural anesthesia on hepatic perfusion and oxygenation in healthy pigs during general anesthesia and surgical stress. Anesth Analg 2003; 97:1824-1832. [PMID: 14633568 DOI: 10.1213/01.ane.0000087062.94268.c5] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Perioperative liver injury due to decreased perfusion may be an underlying mechanism behind the development of systemic inflammatory response syndrome. We designed this animal study to assess whether thoracic epidural anesthesia (TEA) impairs liver oxygenation due to induced hypotension. After ethical approval, 19 anesthetized and acutely instrumented pigs were randomly assigned to 3 groups (control and TEA alone versus TEA plus volume loading). Bupivacaine 0.5% 0.75 mL per segment was injected into the epidural space, aiming for a T5 to T12 block. After baseline values were obtained, measurements were repeated 60 and 120 min after epidural injection. TEA was associated with decreased mean arterial blood pressure but no change in total hepatic blood flow. Oxygen delivery to the liver and oxygen uptake remained unchanged. Liver tissue oxygen partial pressure did not decrease. The plasma indocyanine green disappearance rate remained stable. Volume loading before TEA did not relevantly affect total hepatic blood flow; it even decreased oxygen supply to the liver by hemodilution. We conclude that, despite decreased mean arterial blood pressure, TEA did not affect liver oxygenation. There was no clinically relevant effect of volume loading on total hepatic perfusion.
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Affiliation(s)
- Dierk A Vagts
- *Anaesthesiologische Universitätsklinik Freiburg, Freiburg im Breisgau, Germany; †Klinik und Poliklinik für Anästhesiologie und Intensivtherapie, Universität Rostock, Rostock, Germany; ‡Institut für Experimentelle und Klinische Pharmakologie und Toxikologie der Universität Freiburg, Freiburg im Breisgau, Germany; and §Chirurgische Forschung, Chirurgische Universitätsklinik Freiburg, Freiburg im Breisgau, Germany
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Vagts DA, Iber T, Szabo B, Haberstroh J, Reising K, Puccini M, Geiger K, Nöldge-Schomburg GFE. Effects of epidural anaesthesia on intestinal oxygenation in pigs. Br J Anaesth 2003; 90:212-20. [PMID: 12538379 DOI: 10.1093/bja/aeg039] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Perioperative intestinal hypoperfusion is a major contributing factor leading to organ dysfunction. It can be caused by stress as a result of surgical manipulation or hypoxia. Additionally, anaesthesia can affect intestinal oxygenation. This animal study was designed to assess the effects of reduced regional sympathetic nervous activity induced by thoracic epidural anaesthesia on intestinal oxygenation. METHODS After ethical approval, 16 anaesthetized and acutely instrumented pigs were randomly assigned to two groups (epidural anaesthesia alone vs epidural anaesthesia plus volume loading). The epidural anaesthesia aimed for a T5-T12 block. Measurements were at baseline and after 1 and 2 h. RESULTS Epidural anaesthesia was associated with a decrease in mean arterial blood pressure and pronounced mesenteric vasodilatation. Mesenteric blood flow did not change. Intestinal oxygen uptake, mucosal tissue oxygen partial pressure and tissue carbon dioxide partial pressure remained unchanged. CONCLUSIONS Despite marked systemic hypotension, epidural anaesthesia did not affect intestinal oxygenation. There was no benefit obtained from volume loading.
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Affiliation(s)
- D A Vagts
- Anaesthesiologische Universitätsklinik Freiburg, Hugstetter Strasse 55, D-79106 Freiburg im Breisgau, Germany
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Abstract
AbstractBackground: The diagnostic potential of breath analysis has been limited by a lack of knowledge on origin, distribution, and metabolism of the exhaled substances. To overcome this problem, we developed a method to assess trace amounts of hydrocarbons (pentane and isoprene), ketones (acetone), halogenated compounds (isoflurane), and thioethers (dimethyl sulfide) in the blood of humans and animals.Methods: Arterial and venous blood samples were taken from mechanically ventilated patients. Additional blood samples were taken from selected vascular compartments of 19 mechanically ventilated pigs. Volatile substances were concentrated by means of solid-phase microextraction (SPME), separated by gas chromatography, and identified by mass spectrometry.Results: Detection limits were 0.02–0.10 nmol/L. Venous concentrations in pigs were 0.2–1.3 nmol/L for isoprene, 0–0.3 nmol/L for pentane, and 1.2–15.1 nmol/L for dimethyl sulfide. In pigs, substances were not equally distributed among vascular compartments. In humans, median arteriovenous concentration differences were 3.58 nmol/L for isoprene and 1.56 nmol/L for pentane. These values were comparable to pulmonary excretion rates reported in the literature. Acute respiratory distress syndrome (ARDS) patients had lower isoprene concentration differences than patients without ARDS.Conclusions: The SPME method can detect volatile substances in very low concentrations in the blood of humans and animals. Analysis of volatile substances in vascular compartments will enlarge the diagnostic potential of breath analysis.
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Affiliation(s)
- Wolfram Miekisch
- Department of Anesthesiology and Intensive Care Medicine, University Hospital of Rostock, Schillingallee 35, 18057 Rostock, Germany
| | - Jochen K Schubert
- Department of Anesthesiology and Intensive Care Medicine, University Hospital of Rostock, Schillingallee 35, 18057 Rostock, Germany
| | - Dierk A Vagts
- Department of Anesthesiology and Intensive Care Medicine, University Hospital of Rostock, Schillingallee 35, 18057 Rostock, Germany
| | - Klaus Geiger
- Department of Anesthesiology and Intensive Care Medicine, University Hospital of Freiburg, Hugstetter Strasse 55, 79106 Freiburg, Germany
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Sinaasappel M, van Iterson M, Ince C. Microvascular oxygen pressure in the pig intestine during haemorrhagic shock and resuscitation. J Physiol 1999; 514 ( Pt 1):245-53. [PMID: 9831730 PMCID: PMC2269040 DOI: 10.1111/j.1469-7793.1999.245af.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/1998] [Accepted: 09/24/1998] [Indexed: 11/26/2022] Open
Abstract
1. The aim of this study was to investigate the relation between microvascular and venous oxygen pressures during haemorrhagic shock and resuscitation in the pig intestine. To this end microvascular PO2 (microPO2) was measured by quenching of Pd-porphyrin phosphorescence by oxygen and validated for the intestines. In addition, mesenteric venous blood gasses, blood flow, ilial CO2 production and global haemodynamics were also measured. 2. In one group (n = 11), moderate shock was induced by withdrawal of 40% of the circulating blood volume. Seven of these animals were resuscitated with a crystalloid solution and four with the withdrawn blood. In a second group of three animals, a more severe shock was induced by withdrawal of 50% of the circulating blood volume; these animals were not resuscitated. 3. Baseline mesenteric venous PO2 and microPO2 values were similar (60 +/- 9 and 60 +/- 11 mmHg, respectively). During moderate shock, microPO2 dropped significantly below mesenteric venous PO2 (26 +/- 10 versus 35 +/- 8 mmHg). After resuscitation with crystalloid solution, microPO2 and mesenteric venous PO2 rose to 44 +/- 9 and 44 +/- 6 mmHg, respectively. In the group that received the withdrawn blood, values were 41 +/- 9 and 53 +/- 12 mmHg, respectively. Severe shock resulted in a drop in the mesenteric venous PO2 (n = 3) to a value similar to that seen in the moderate shock group, but the gut microPO2 dropped to a much lower value than that of the moderate shock group (15 +/- 5 versus 26 +/- 10 mmHg). 4. The results indicate that the oxygenation of the microcirculation of the gut can become lower than the venous PO2 under conditions of haemorrhagic shock.
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Affiliation(s)
- M Sinaasappel
- Departments of Anaesthesiology, Academic Medical Centre, University of Amsterdam, The Netherlands
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Tao W, Zwischenberger JB, Kramer GC. Rapid monitoring of gastrointestinal intraluminal PCO2 as an end-organ perfusion index. Crit Care Med 1997; 25:1458-9. [PMID: 9295816 DOI: 10.1097/00003246-199709000-00009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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