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Evans RG. Another step forward for methods for studying renal oxygenation. Kidney Int 2020; 96:552-554. [PMID: 31445583 DOI: 10.1016/j.kint.2019.05.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 05/02/2019] [Accepted: 05/07/2019] [Indexed: 11/16/2022]
Abstract
All available methods for assessing renal oxygenation are limited either in terms of their temporal or spatial resolution, their ability to quantify tissue oxygen tension (PO2), or in the settings in which they can be applied. Kodama and colleagues have developed a new method that utilizes dynamic nuclear polarization magnetic resonance imaging and an oxygen-sensitive paramagnetic agent (OX63). This new method generates quantitative maps of renal tissue PO2 in millimeters of mercury.
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Affiliation(s)
- Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia.
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2
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Ullah MM, Ow CPC, Hilliard Krause LM, Evans RG. Renal oxygenation during the early stages of adenine-induced chronic kidney disease. Am J Physiol Renal Physiol 2019; 317:F1189-F1200. [DOI: 10.1152/ajprenal.00253.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
To assess whether renal hypoxia is an early event in adenine-induced chronic kidney disease, adenine (100 mg) or its vehicle was administered to male Sprague-Dawley rats by daily oral gavage for 7 days. Kidney oxygenation was assessed by 1) blood oximetry and Clark electrode in thiobutabarbital-anesthetized rats, 2) radiotelemetry in unanesthetized rats, and 3) expression of hypoxia-inducible factor (HIF)-1α and HIF-2α protein. After 7 days of treatment, under anesthesia, renal O2 delivery was 51% less, whereas renal O2 consumption was 65% less, in adenine-treated rats than in vehicle-treated rats. Tissue Po2 measured by Clark electrode was similar in the renal cortex but 44% less in the medulla of adenine-treated rats than in that of vehicle-treated rats. In contrast, in unanesthetized rats, both cortical and medullary tissue Po2 measured by radiotelemetry remained stable across 7 days of adenine treatment. Notably, anesthesia and laparotomy led to greater reductions in medullary tissue Po2 measured by radiotelemetry in rats treated with adenine (37%) than in vehicle-treated rats (16%), possibly explaining differences between our observations with Clark electrodes and radiotelemetry. Renal expression of HIF-1α was less after 7 days of adenine treatment than after vehicle treatment, whereas expression of HIF-2α did not differ significantly between the two groups. Renal dysfunction was evident after 7 days of adenine treatment, with glomerular filtration rate 65% less and serum creatinine concentration 183% greater in adenine-treated rats than in vehicle-treated rats. Renal cortical tissue hypoxia may not precede renal dysfunction in adenine-induced chronic kidney disease and so may not be an early pathological feature in this model.
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Affiliation(s)
- Md Mahbub Ullah
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University, Melbourne, Victoria, Australia
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Connie P. C. Ow
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University, Melbourne, Victoria, Australia
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
| | - Lucinda M. Hilliard Krause
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Roger G. Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University, Melbourne, Victoria, Australia
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Adamovich Y, Ladeuix B, Sobel J, Manella G, Neufeld-Cohen A, Assadi MH, Golik M, Kuperman Y, Tarasiuk A, Koeners MP, Asher G. Oxygen and Carbon Dioxide Rhythms Are Circadian Clock Controlled and Differentially Directed by Behavioral Signals. Cell Metab 2019; 29:1092-1103.e3. [PMID: 30773466 DOI: 10.1016/j.cmet.2019.01.007] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 11/13/2018] [Accepted: 01/16/2019] [Indexed: 12/25/2022]
Abstract
Daily rhythms in animal physiology are driven by endogenous circadian clocks in part through rest-activity and feeding-fasting cycles. Here, we examined principles that govern daily respiration. We monitored oxygen consumption and carbon dioxide release, as well as tissue oxygenation in freely moving animals to specifically dissect the role of circadian clocks and feeding time on daily respiration. We found that daily rhythms in oxygen and carbon dioxide are clock controlled and that time-restricted feeding restores their rhythmicity in clock-deficient mice. Remarkably, day-time feeding dissociated oxygen rhythms from carbon dioxide oscillations, whereby oxygen followed activity, and carbon dioxide was shifted and aligned with food intake. In addition, changes in carbon dioxide levels altered clock gene expression and phase shifted the clock. Collectively, our findings indicate that oxygen and carbon dioxide rhythms are clock controlled and feeding regulated and support a potential role for carbon dioxide in phase resetting peripheral clocks upon feeding.
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Affiliation(s)
- Yaarit Adamovich
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Benjamin Ladeuix
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Jonathan Sobel
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Gal Manella
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Adi Neufeld-Cohen
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Mohammad H Assadi
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Marina Golik
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yael Kuperman
- Department of Veterinary Resources, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ariel Tarasiuk
- Sleep-Wake Disorders Unit, Soroka University Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Maarten P Koeners
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, University of Exeter, Exeter, UK
| | - Gad Asher
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel.
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Zhang X, Liu CB, Yang DG, Qin C, Dong XC, Li DP, Zhang C, Guo Y, Du LJ, Gao F, Yang ML, Li JJ. Dynamic changes in intramedullary pressure 72 hours after spinal cord injury. Neural Regen Res 2019; 14:886-895. [PMID: 30688275 PMCID: PMC6375044 DOI: 10.4103/1673-5374.249237] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Intramedullary pressure increases after spinal cord injury, and this can be an important factor for secondary spinal cord injury. Until now there have been no studies of the dynamic changes of intramedullary pressure after spinal cord injury. In this study, telemetry systems were used to observe changes in intramedullary pressure in the 72 hours following spinal cord injury to explore its pathological mechanisms. Spinal cord injury was induced using an aneurysm clip at T10 of the spinal cord of 30 Japanese white rabbits, while another 32 animals were only subjected to laminectomy. The feasibility of this measurement was assessed. Intramedullary pressure was monitored in anesthetized and conscious animals. The dynamic changes of intramedullary pressure after spinal cord injury were divided into three stages: stage I (steep rise) 1–7 hours, stage II (steady rise) 8–38 hours, and stage III (descending) 39–72 hours. Blood-spinal barrier permeability, edema, hemorrhage, and histological results in the 72 hours following spinal cord injury were evaluated according to intramedullary pressure changes. We found that spinal cord hemorrhage was most severe at 1 hour post-spinal cord injury and then gradually decreased; albumin and aquaporin 4 immunoreactivities first increased and then decreased, peaking at 38 hours. These results confirm that severe bleeding in spinal cord tissue is the main cause of the sharp increase in intramedullary pressure in early spinal cord injury. Spinal cord edema and blood-spinal barrier destruction are important factors influencing intramedullary pressure in stages II and III of spinal cord injury.
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Affiliation(s)
- Xin Zhang
- School of Rehabilitation Medicine, Capital Medical University; Department of Spinal and Neural Function Reconstruction, China Rehabilitation Research Center; Center of Neural Injury and Repair, Beijing Institute for Brain Disorders; China Rehabilitation Science Institute; Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
| | - Chang-Bin Liu
- School of Rehabilitation Medicine, Capital Medical University; Department of Spinal and Neural Function Reconstruction, China Rehabilitation Research Center; Center of Neural Injury and Repair, Beijing Institute for Brain Disorders; China Rehabilitation Science Institute; Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
| | - De-Gang Yang
- School of Rehabilitation Medicine, Capital Medical University; Department of Spinal and Neural Function Reconstruction, China Rehabilitation Research Center; Center of Neural Injury and Repair, Beijing Institute for Brain Disorders; China Rehabilitation Science Institute; Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
| | - Chuan Qin
- School of Rehabilitation Medicine, Capital Medical University; Department of Spinal and Neural Function Reconstruction, China Rehabilitation Research Center; Center of Neural Injury and Repair, Beijing Institute for Brain Disorders; China Rehabilitation Science Institute; Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
| | - Xue-Chao Dong
- School of Rehabilitation Medicine, Capital Medical University; Department of Spinal and Neural Function Reconstruction, China Rehabilitation Research Center; Center of Neural Injury and Repair, Beijing Institute for Brain Disorders; China Rehabilitation Science Institute; Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
| | - Da-Peng Li
- School of Rehabilitation Medicine, Capital Medical University; Department of Spinal and Neural Function Reconstruction, China Rehabilitation Research Center; Center of Neural Injury and Repair, Beijing Institute for Brain Disorders; China Rehabilitation Science Institute; Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
| | - Chao Zhang
- School of Rehabilitation Medicine, Capital Medical University; Department of Spinal and Neural Function Reconstruction, China Rehabilitation Research Center; Center of Neural Injury and Repair, Beijing Institute for Brain Disorders; China Rehabilitation Science Institute; Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
| | - Yun Guo
- School of Rehabilitation Medicine, Capital Medical University; Department of Spinal and Neural Function Reconstruction, China Rehabilitation Research Center; Center of Neural Injury and Repair, Beijing Institute for Brain Disorders; China Rehabilitation Science Institute; Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
| | - Liang-Jie Du
- School of Rehabilitation Medicine, Capital Medical University; Department of Spinal and Neural Function Reconstruction, China Rehabilitation Research Center; Center of Neural Injury and Repair, Beijing Institute for Brain Disorders; China Rehabilitation Science Institute; Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
| | - Feng Gao
- School of Rehabilitation Medicine, Capital Medical University; Department of Spinal and Neural Function Reconstruction, China Rehabilitation Research Center; Center of Neural Injury and Repair, Beijing Institute for Brain Disorders; China Rehabilitation Science Institute; Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
| | - Ming-Liang Yang
- School of Rehabilitation Medicine, Capital Medical University; Department of Spinal and Neural Function Reconstruction, China Rehabilitation Research Center; Center of Neural Injury and Repair, Beijing Institute for Brain Disorders; China Rehabilitation Science Institute; Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
| | - Jian-Jun Li
- School of Rehabilitation Medicine, Capital Medical University; Department of Spinal and Neural Function Reconstruction, China Rehabilitation Research Center; Center of Neural Injury and Repair, Beijing Institute for Brain Disorders; China Rehabilitation Science Institute; Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
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5
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Emans TW, Patinha D, Joles JA, Koeners MP, Janssen BJ, Krediet CTP. Angiotensin II-induced hypertension in rats is only transiently accompanied by lower renal oxygenation. Sci Rep 2018; 8:16342. [PMID: 30397212 DOI: 10.1038/s41598-018-34211-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 10/09/2018] [Indexed: 02/08/2023] Open
Abstract
Activation of the renin-angiotensin system may initiate chronic kidney disease. We hypothesised that renal hypoxia is a consequence of hemodynamic changes induced by angiotensin II and occurs prior to development of severe renal damage. Male Sprague-Dawley rats were infused continuously with angiotensin II (350 ng/kg/min) for 8 days. Mean arterial pressure (n = 5), cortical (n = 6) and medullary (n = 7) oxygenation (pO2) were continuously recorded by telemetry and renal tissue injury was scored. Angiotensin II increased arterial pressure gradually to 150 ± 18 mmHg. This was associated with transient reduction of oxygen levels in renal cortex (by 18 ± 2%) and medulla (by 17 ± 6%) at 10 ± 2 and 6 ± 1 hours, respectively after starting infusion. Thereafter oxygen levels normalised to pre-infusion levels and were maintained during the remainder of the infusion period. In rats receiving angiotensin II, adding losartan to drinking water (300 mg/L) only induced transient increase in renal oxygenation, despite normalisation of arterial pressure. In rats, renal hypoxia is only a transient phenomenon during initiation of angiotensin II-induced hypertension.
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Ow CPC, Ngo JP, Ullah MM, Barsha G, Meex RC, Watt MJ, Hilliard LM, Koeners MP, Evans RG. Absence of renal hypoxia in the subacute phase of severe renal ischemia-reperfusion injury. Am J Physiol Renal Physiol 2018; 315:F1358-F1369. [PMID: 30110566 PMCID: PMC6293301 DOI: 10.1152/ajprenal.00249.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Tissue hypoxia has been proposed as an important event in renal ischemia-reperfusion injury (IRI), particularly during the period of ischemia and in the immediate hours following reperfusion. However, little is known about renal oxygenation during the subacute phase of IRI. We employed four different methods to assess the temporal and spatial changes in tissue oxygenation during the subacute phase (24 h and 5 days after reperfusion) of a severe form of renal IRI in rats. We hypothesized that the kidney is hypoxic 24 h and 5 days after an hour of bilateral renal ischemia, driven by a disturbed balance between renal oxygen delivery (Do2) and oxygen consumption (V̇o2). Renal Do2 was not significantly reduced in the subacute phase of IRI. In contrast, renal V̇o2 was 55% less 24 h after reperfusion and 49% less 5 days after reperfusion than after sham ischemia. Inner medullary tissue Po2, measured by radiotelemetry, was 25 ± 12% (mean ± SE) greater 24 h after ischemia than after sham ischemia. By 5 days after reperfusion, tissue Po2 was similar to that in rats subjected to sham ischemia. Tissue Po2 measured by Clark electrode was consistently greater 24 h, but not 5 days, after ischemia than after sham ischemia. Cellular hypoxia, assessed by pimonidazole adduct immunohistochemistry, was largely absent at both time points, and tissue levels of hypoxia-inducible factors were downregulated following renal ischemia. Thus, in this model of severe IRI, tissue hypoxia does not appear to be an obligatory event during the subacute phase, likely because of the markedly reduced oxygen consumption.
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Affiliation(s)
- Connie P C Ow
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University , Melbourne, Victoria , Australia
| | - Jennifer P Ngo
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University , Melbourne, Victoria , Australia
| | - Md Mahbub Ullah
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University , Melbourne, Victoria , Australia
| | - Giannie Barsha
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University , Melbourne, Victoria , Australia
| | - Ruth C Meex
- Department of Human Biology, NUTRIM School of Nutritional and Translational Research in Metabolism, Maastricht University Medical Centre , Maastricht , The Netherlands
| | - Matthew J Watt
- Metabolism, Diabetes and Obesity Program, Biomedicine Discovery Institute, Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Lucinda M Hilliard
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University , Melbourne, Victoria , Australia
| | - Maarten P Koeners
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences, University of Bristol , Bristol , United Kingdom.,Institute of Biomedical and Clinical Science, University of Exeter Medical School , Exeter , United Kingdom
| | - Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute, Department of Physiology, Monash University , Melbourne, Victoria , Australia
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7
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Abstract
Background Renal hypoxia, implicated as crucial factor in onset and progression of chronic kidney disease, may be attributed to reduced nitric oxide because nitric oxide dilates vasculature and inhibits mitochondrial oxygen consumption. We hypothesized that chronic nitric oxide synthase inhibition would induce renal hypoxia. Methods and Results Oxygen-sensitive electrodes, attached to telemeters, were implanted in either renal cortex (n=6) or medulla (n=7) in rats. After recovery and stabilization, baseline oxygenation ( pO 2) was recorded for 1 week. To inhibit nitric oxide synthase, N-ω-nitro-l-arginine (L-NNA; 40 mg/kg/day) was administered via drinking water for 2 weeks. A separate group (n=8), instrumented with blood pressure telemeters, followed the same protocol. L-NNA rapidly induced hypertension (165±6 versus 108±3 mm Hg; P<0.001) and proteinuria (79±12 versus 17±2 mg/day; P<0.001). Cortical pO 2, after initially dipping, returned to baseline and then increased. Medullary pO 2 decreased progressively (up to -19±6% versus baseline; P<0.05). After 14 days of L-NNA, amplitude of diurnal medullary pO 2 was decreased (3.7 [2.2-5.3] versus 7.9 [7.5-8.4]; P<0.01), whereas amplitudes of blood pressure and cortical pO 2 were unaltered. Terminal glomerular filtration rate (1374±74 versus 2098±122 μL/min), renal blood flow (5014±336 versus 9966±905 μL/min), and sodium reabsorption efficiency (13.0±0.8 versus 22.8±1.7 μmol/μmol) decreased (all P<0.001). Conclusions For the first time, we show temporal development of renal cortical and medullary oxygenation during chronic nitric oxide synthase inhibition in unrestrained conscious rats. Whereas cortical pO 2 shows transient changes, medullary pO 2 decreased progressively. Chronic L-NNA leads to decreased renal perfusion and sodium reabsorption efficiency, resulting in progressive medullary hypoxia, suggesting that juxtamedullary nephrons are potentially vulnerable to prolonged nitric oxide depletion.
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Affiliation(s)
- Tonja W. Emans
- Internal Medicine‐NephrologyAmsterdam UMC / Academic Medical Centre at the University of AmsterdamThe Netherlands
- Nephrology and HypertensionUniversity Medical Centre UtrechtThe Netherlands
| | - Ben J. Janssen
- Pharmacology and ToxicologyMaastricht UniversityThe Netherlands
| | - Jaap A. Joles
- Nephrology and HypertensionUniversity Medical Centre UtrechtThe Netherlands
| | - C.T. Paul Krediet
- Internal Medicine‐NephrologyAmsterdam UMC / Academic Medical Centre at the University of AmsterdamThe Netherlands
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Ow CPC, Ngo JP, Ullah MM, Hilliard LM, Evans RG. Renal hypoxia in kidney disease: Cause or consequence? Acta Physiol (Oxf) 2018; 222:e12999. [PMID: 29159875 DOI: 10.1111/apha.12999] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 11/10/2017] [Accepted: 11/15/2017] [Indexed: 02/06/2023]
Abstract
Tissue hypoxia has been proposed as an important factor in the pathophysiology of both chronic kidney disease (CKD) and acute kidney injury (AKI), initiating and propagating a vicious cycle of tubular injury, vascular rarefaction, and fibrosis and thus exacerbation of hypoxia. Here, we critically evaluate this proposition by systematically reviewing the literature relevant to the following six questions: (i) Is kidney disease always associated with tissue hypoxia? (ii) Does tissue hypoxia drive signalling cascades that lead to tissue damage and dysfunction? (iii) Does tissue hypoxia per se lead to kidney disease? (iv) Does tissue hypoxia precede pathology? (v) Does tissue hypoxia colocalize with pathology? (vi) Does prevention of tissue hypoxia prevent kidney disease? We conclude that tissue hypoxia is a common feature of both AKI and CKD. Furthermore, at least under in vitro conditions, renal tissue hypoxia drives signalling cascades that lead to tissue damage and dysfunction. Tissue hypoxia itself can lead to renal pathology, independent of other known risk factors for kidney disease. There is also some evidence that tissue hypoxia precedes renal pathology, at least in some forms of kidney disease. However, we have made relatively little progress in determining the spatial relationships between tissue hypoxia and pathological processes (i.e. colocalization) or whether therapies targeted to reduce tissue hypoxia can prevent or delay the progression of renal disease. Thus, the hypothesis that tissue hypoxia is a "common pathway" to both AKI and CKD still remains to be adequately tested.
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Affiliation(s)
- C. P. C. Ow
- Cardiovascular Disease Program Biomedicine Discovery Institute and Department of Physiology Monash University Melbourne Vic. Australia
| | - J. P. Ngo
- Cardiovascular Disease Program Biomedicine Discovery Institute and Department of Physiology Monash University Melbourne Vic. Australia
| | - M. M. Ullah
- Cardiovascular Disease Program Biomedicine Discovery Institute and Department of Physiology Monash University Melbourne Vic. Australia
| | - L. M. Hilliard
- Cardiovascular Disease Program Biomedicine Discovery Institute and Department of Physiology Monash University Melbourne Vic. Australia
| | - R. G. Evans
- Cardiovascular Disease Program Biomedicine Discovery Institute and Department of Physiology Monash University Melbourne Vic. Australia
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9
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Abstract
Blood pressure, renal hemodynamics, electrolyte, and water excretion all display diurnal oscillation. Disturbance of these patterns is associated with hypertension and chronic kidney disease. Kidney oxygenation is dependent on oxygen delivery and consumption that in turn are determined by renal hemodynamics and metabolism. We hypothesized that kidney oxygenation also demonstrates 24-h periodicity. Telemetric oxygen-sensitive carbon paste electrodes were implanted in Sprague-Dawley rats (250–300 g), either in renal medulla (n = 9) or cortex (n = 7). Arterial pressure (MAP) and heart rate (HR) were monitored by telemetry in a separate group (n = 8). Data from 5 consecutive days were analyzed for rhythmicity by cosinor analysis. Diurnal electrolyte excretion was assessed by metabolic cages. During lights-off, oxygen levels increased to 105.3 ± 2.1% in cortex and 105.2 ± 3.8% in medulla. MAP was 97.3 ± 1.5 mmHg and HR was 394.0 ± 7.9 bpm during lights-off phase and 93.5 ± 1.3 mmHg and 327.8 ± 8.9 bpm during lights-on. During lights-on, oxygen levels decreased to 94.6 ± 1.4% in cortex and 94.2 ± 8.5% in medulla. There was significant 24-h periodicity in cortex and medulla oxygenation. Potassium excretion (1,737 ± 779 vs. 895 ± 132 μmol/12 h, P = 0.005) and the distal Na+/K+ exchange (0.72 ± 0.02 vs. 0.59 ± 0.02 P < 0.001) were highest in the lights-off phase, this phase difference was not found for sodium excretion (P = 0.4). It seems that oxygen levels in the kidneys follow the pattern of oxygen delivery, which is known to be determined by renal blood flow and peaks in the active phase (lights-off).
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Affiliation(s)
- Tonja W Emans
- Department of Internal Medicine, Academic Medical Center at the University of AmsterdamAmsterdam, Netherlands.,Department of Nephrology and Hypertension, University Medical Center UtrechtUtrecht, Netherlands
| | - Ben J Janssen
- Department of Pharmacology and Toxicology, Maastricht UniversityMaastricht, Netherlands
| | - Jaap A Joles
- Department of Nephrology and Hypertension, University Medical Center UtrechtUtrecht, Netherlands
| | - C T Paul Krediet
- Department of Internal Medicine, Academic Medical Center at the University of AmsterdamAmsterdam, Netherlands
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Adamovich Y, Ladeuix B, Golik M, Koeners MP, Asher G. Rhythmic Oxygen Levels Reset Circadian Clocks through HIF1α. Cell Metab 2017; 25:93-101. [PMID: 27773695 DOI: 10.1016/j.cmet.2016.09.014] [Citation(s) in RCA: 186] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 09/02/2016] [Accepted: 09/23/2016] [Indexed: 12/19/2022]
Abstract
The mammalian circadian system consists of a master clock in the brain that synchronizes subsidiary oscillators in peripheral tissues. The master clock maintains phase coherence in peripheral cells through systemic cues such as feeding-fasting and temperature cycles. Here, we examined the role of oxygen as a resetting cue for circadian clocks. We continuously measured oxygen levels in living animals and detected daily rhythms in tissue oxygenation. Oxygen cycles, within the physiological range, were sufficient to synchronize cellular clocks in a HIF1α-dependent manner. Furthermore, several clock genes responded to changes in oxygen levels through HIF1α. Finally, we found that a moderate reduction in oxygen levels for a short period accelerates the adaptation of wild-type but not of HIF1α-deficient mice to the new time in a jet lag protocol. We conclude that oxygen, via HIF1α activation, is a resetting cue for circadian clocks and propose oxygen modulation as therapy for jet lag.
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Affiliation(s)
- Yaarit Adamovich
- Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Benjamin Ladeuix
- Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Marina Golik
- Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Maarten P Koeners
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol BS8 1TH, UK
| | - Gad Asher
- Department of Biomolecular Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel.
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11
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Emans TW, Janssen BJ, Pinkham MI, Ow CPC, Evans RG, Joles JA, Malpas SC, Krediet CTP, Koeners MP. Exogenous and endogenous angiotensin-II decrease renal cortical oxygen tension in conscious rats by limiting renal blood flow. J Physiol 2016; 594:6287-6300. [PMID: 27426098 PMCID: PMC5088249 DOI: 10.1113/jp270731] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 07/08/2016] [Indexed: 01/08/2023] Open
Abstract
KEY POINTS Our understanding of the mechanisms underlying the role of hypoxia in the initiation and progression of renal disease remains rudimentary. We have developed a method that allows wireless measurement of renal tissue oxygen tension in unrestrained rats. This method provides stable and continuous measurements of cortical tissue oxygen tension (PO2) for more than 2 weeks and can reproducibly detect acute changes in cortical oxygenation. Exogenous angiotensin-II reduced renal cortical tissue PO2 more than equi-pressor doses of phenylephrine, probably because it reduced renal oxygen delivery more than did phenylephrine. Activation of the endogenous renin-angiotensin system in transgenic Cyp1a1Ren2 rats reduced cortical tissue PO2; in this model renal hypoxia precedes the development of structural pathology and can be reversed acutely by an angiotensin-II receptor type 1 antagonist. Angiotensin-II promotes renal hypoxia, which may in turn contribute to its pathological effects during development of chronic kidney disease. ABSTRACT We hypothesised that both exogenous and endogenous angiotensin-II (AngII) can decrease the partial pressure of oxygen (PO2) in the renal cortex of unrestrained rats, which might in turn contribute to the progression of chronic kidney disease. Rats were instrumented with telemeters equipped with a carbon paste electrode for continuous measurement of renal cortical tissue PO2. The method reproducibly detected acute changes in cortical oxygenation induced by systemic hyperoxia and hypoxia. In conscious rats, renal cortical PO2 was dose-dependently reduced by intravenous AngII. Reductions in PO2 were significantly greater than those induced by equi-pressor doses of phenylephrine. In anaesthetised rats, renal oxygen consumption was not affected, and filtration fraction was increased only in the AngII infused animals. Oxygen delivery decreased by 50% after infusion of AngII and renal blood flow (RBF) fell by 3.3 ml min-1 . Equi-pressor infusion of phenylephrine did not significantly reduce RBF or renal oxygen delivery. Activation of the endogenous renin-angiotensin system in Cyp1a1Ren2 transgenic rats reduced cortical tissue PO2. This could be reversed within minutes by pharmacological angiotensin-II receptor type 1 (AT1 R) blockade. Thus AngII is an important modulator of renal cortical oxygenation via AT1 receptors. AngII had a greater influence on cortical oxygenation than did phenylephrine. This phenomenon appears to be attributable to the profound impact of AngII on renal oxygen delivery. We conclude that the ability of AngII to promote renal cortical hypoxia may contribute to its influence on initiation and progression of chronic kidney disease.
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Affiliation(s)
- Tonja W Emans
- Nephrology and Hypertension, University Medical Centre Utrecht, Utrecht, The Netherlands.,Internal Medicine-Nephrology, Academic Medical Centre at the University of Amsterdam, The Netherlands
| | - Ben J Janssen
- Department of Pharmacology and Toxicology, Maastricht University, Maastricht, The Netherlands
| | | | - Connie P C Ow
- Cardiovascular Disease Program, Biosciences Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia
| | - Roger G Evans
- Cardiovascular Disease Program, Biosciences Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia
| | - Jaap A Joles
- Nephrology and Hypertension, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Simon C Malpas
- Department of Physiology, University of Auckland, Auckland, New Zealand.,Millar Inc, Auckland, New Zealand
| | - C T Paul Krediet
- Internal Medicine-Nephrology, Academic Medical Centre at the University of Amsterdam, The Netherlands
| | - Maarten P Koeners
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK.
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