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Ow CPC, Okazaki N, Iguchi N, Peiris RM, Evans RG, Hood SG, May CN, Bellomo R, Lankadeva YR. Effects of furosemide, acetazolamide and amiloride on renal cortical and medullary tissue oxygenation in non-anaesthetised healthy sheep. Exp Physiol 2024; 109:766-778. [PMID: 38551893 PMCID: PMC11061632 DOI: 10.1113/ep091479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 03/13/2024] [Indexed: 05/02/2024]
Abstract
It has been proposed that diuretics can improve renal tissue oxygenation through inhibition of tubular sodium reabsorption and reduced metabolic demand. However, the impact of clinically used diuretic drugs on the renal cortical and medullary microcirculation is unclear. Therefore, we examined the effects of three commonly used diuretics, at clinically relevant doses, on renal cortical and medullary perfusion and oxygenation in non-anaesthetised healthy sheep. Merino ewes received acetazolamide (250 mg; n = 9), furosemide (20 mg; n = 10) or amiloride (10 mg; n = 7) intravenously. Systemic and renal haemodynamics, renal cortical and medullary tissue perfusion andP O 2 ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ , and renal function were then monitored for up to 8 h post-treatment. The peak diuretic response occurred 2 h (99.4 ± 14.8 mL/h) after acetazolamide, at which stage cortical and medullary tissue perfusion andP O 2 ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ were not significantly different from their baseline levels. The peak diuretic response to furosemide occurred at 1 h (196.5 ± 12.3 mL/h) post-treatment but there were no significant changes in cortical and medullary tissue oxygenation during this period. However, cortical tissueP O 2 ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ fell from 40.1 ± 3.8 mmHg at baseline to 17.2 ± 4.4 mmHg at 3 h and to 20.5 ± 5.3 mmHg at 6 h after furosemide administration. Amiloride did not produce a diuretic response and was not associated with significant changes in cortical or medullary tissue oxygenation. In conclusion, clinically relevant doses of diuretic agents did not improve regional renal tissue oxygenation in healthy animals during the 8 h experimentation period. On the contrary, rebound renal cortical hypoxia may develop after dissipation of furosemide-induced diuresis.
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Affiliation(s)
- Connie P. C. Ow
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthUniversity of MelbourneMelbourneVictoriaAustralia
| | - Nobuki Okazaki
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthUniversity of MelbourneMelbourneVictoriaAustralia
- Department of Anesthesiology and ResuscitologyOkayama UniversityOkayamaJapan
| | - Naoya Iguchi
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthUniversity of MelbourneMelbourneVictoriaAustralia
- Department of Anesthesiology and Intensive Care MedicineGraduate School of MedicineOsaka UniversityOsakaJapan
| | - Rachel M. Peiris
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthUniversity of MelbourneMelbourneVictoriaAustralia
| | - Roger G. Evans
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthUniversity of MelbourneMelbourneVictoriaAustralia
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of PhysiologyMonash UniversityMelbourneVictoriaAustralia
| | - Sally G. Hood
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthUniversity of MelbourneMelbourneVictoriaAustralia
| | - Clive N. May
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthUniversity of MelbourneMelbourneVictoriaAustralia
- Department of Critical Care, Melbourne Medical SchoolUniversity of MelbourneMelbourneVictoriaAustralia
| | - Rinaldo Bellomo
- Department of Critical Care, Melbourne Medical SchoolUniversity of MelbourneMelbourneVictoriaAustralia
- Australian and New Zealand Intensive Care Research Centre (ANZIC‐RC), School of Public Health and Preventive MedicineMonash UniversityMelbourneAustralia
- Department of Intensive CareAustin HospitalMelbourneAustralia
- Department of Intensive CareRoyal Melbourne HospitalMelbourneAustralia
- Data Analytics Research and Evaluation CentreAustin HospitalMelbourneAustralia
| | - Yugeesh R. Lankadeva
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthUniversity of MelbourneMelbourneVictoriaAustralia
- Department of Critical Care, Melbourne Medical SchoolUniversity of MelbourneMelbourneVictoriaAustralia
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Evans RG, Cochrane AD, Hood SG, Marino B, Iguchi N, Bellomo R, McCall PR, Okazaki N, Jufar AH, Miles LF, Furukawa T, Ow CPC, Raman J, May CN, Lankadeva YR. Differential responses of cerebral and renal oxygenation to altered perfusion conditions during experimental cardiopulmonary bypass in sheep. Clin Exp Pharmacol Physiol 2024; 51:e13852. [PMID: 38452756 DOI: 10.1111/1440-1681.13852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Revised: 01/23/2024] [Accepted: 02/13/2024] [Indexed: 03/09/2024]
Abstract
We tested whether the brain and kidney respond differently to cardiopulmonary bypass (CPB) and to changes in perfusion conditions during CPB. Therefore, in ovine CPB, we assessed regional cerebral oxygen saturation (rSO2 ) by near-infrared spectroscopy and renal cortical and medullary tissue oxygen tension (PO2 ), and, in some protocols, brain tissue PO2 , by phosphorescence lifetime oximetry. During CPB, rSO2 correlated with mixed venous SO2 (r = 0.78) and brain tissue PO2 (r = 0.49) when arterial PO2 was varied. During the first 30 min of CPB, brain tissue PO2 , rSO2 and renal cortical tissue PO2 did not fall, but renal medullary tissue PO2 did. Nevertheless, compared with stable anaesthesia, during stable CPB, rSO2 (66.8 decreasing to 61.3%) and both renal cortical (90.8 decreasing to 43.5 mm Hg) and medullary (44.3 decreasing to 19.2 mm Hg) tissue PO2 were lower. Both rSO2 and renal PO2 increased when pump flow was increased from 60 to 100 mL kg-1 min-1 at a target arterial pressure of 70 mm Hg. They also both increased when pump flow and arterial pressure were increased simultaneously. Neither was significantly altered by partially pulsatile flow. The vasopressor, metaraminol, dose-dependently decreased rSO2 , but increased renal cortical and medullary PO2 . Increasing blood haemoglobin concentration increased rSO2 , but not renal PO2 . We conclude that both the brain and kidney are susceptible to hypoxia during CPB, which can be alleviated by increasing pump flow, even without increasing arterial pressure. However, increasing blood haemoglobin concentration increases brain, but not kidney oxygenation, whereas vasopressor support with metaraminol increases kidney, but not brain oxygenation.
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Affiliation(s)
- Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, Australia
- Pre-clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Andrew D Cochrane
- Department of Cardiothoracic Surgery, Monash Health and Department of Surgery (School of Clinical Sciences at Monash Health), Monash University, Melbourne, Victoria, Australia
| | - Sally G Hood
- Pre-clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Bruno Marino
- Cellsaving and Perfusion Resources, Melbourne, Victoria, Australia
| | - Naoya Iguchi
- Pre-clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
- Department of Anesthesiology and Intensive Care Medicine, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Rinaldo Bellomo
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, Australia
- Department of Intensive Care, Austin Health, Heidelberg, Victoria, Australia
- Department of Critical Care, Melbourne Medical School, University of Melbourne, Victoria, Australia
| | - Peter R McCall
- Department of Critical Care, Melbourne Medical School, University of Melbourne, Victoria, Australia
- Department of Anaesthesia, Austin Health, Heidelberg, Victoria, Australia
| | - Nobuki Okazaki
- Pre-clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
- Department of Anesthesiology and Resuscitology, Okayama University, Okayama, Japan
| | - Alemayehu H Jufar
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, Australia
- Pre-clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Lachlan F Miles
- Pre-clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
- Department of Critical Care, Melbourne Medical School, University of Melbourne, Victoria, Australia
- Department of Anaesthesia, Austin Health, Heidelberg, Victoria, Australia
| | - Taku Furukawa
- Pre-clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Connie P C Ow
- Pre-clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Jaishankar Raman
- Department of Intensive Care, Austin Health, Heidelberg, Victoria, Australia
- Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Victoria, Australia
| | - Clive N May
- Pre-clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
- Department of Critical Care, Melbourne Medical School, University of Melbourne, Victoria, Australia
| | - Yugeesh R Lankadeva
- Pre-clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
- Department of Critical Care, Melbourne Medical School, University of Melbourne, Victoria, Australia
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Betrie AH, Ma S, Ow CPC, Peiris RM, Evans RG, Ayton S, Lane DJR, Southon A, Bailey SR, Bellomo R, May CN, Lankadeva YR. Renal arterial infusion of tempol prevents medullary hypoperfusion, hypoxia, and acute kidney injury in ovine Gram-negative sepsis. Acta Physiol (Oxf) 2023; 239:e14025. [PMID: 37548350 PMCID: PMC10909540 DOI: 10.1111/apha.14025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 07/05/2023] [Accepted: 07/21/2023] [Indexed: 08/08/2023]
Abstract
AIM Renal medullary hypoperfusion and hypoxia precede acute kidney injury (AKI) in ovine sepsis. Oxidative/nitrosative stress, inflammation, and impaired nitric oxide generation may contribute to such pathophysiology. We tested whether the antioxidant and anti-inflammatory drug, tempol, may modify these responses. METHODS Following unilateral nephrectomy, we inserted renal arterial catheters and laser-Doppler/oxygen-sensing probes in the renal cortex and medulla. Noanesthetized sheep were administered intravenous (IV) Escherichia coli and, at sepsis onset, IV tempol (IVT; 30 mg kg-1 h-1 ), renal arterial tempol (RAT; 3 mg kg-1 h-1 ), or vehicle. RESULTS Septic sheep receiving vehicle developed renal medullary hypoperfusion (76 ± 16% decrease in perfusion), hypoxia (70 ± 13% decrease in oxygenation), and AKI (87 ± 8% decrease in creatinine clearance) with similar changes during IVT. However, RAT preserved medullary perfusion (1072 ± 307 to 1005 ± 271 units), oxygenation (46 ± 8 to 43 ± 6 mmHg), and creatinine clearance (61 ± 10 to 66 ± 20 mL min-1 ). Plasma, renal medullary, and cortical tissue malonaldehyde and medullary 3-nitrotyrosine decreased significantly with sepsis but were unaffected by IVT or RAT. Consistent with decreased oxidative/nitrosative stress markers, cortical and medullary nuclear factor-erythroid-related factor-2 increased significantly and were unaffected by IVT or RAT. However, RAT prevented sepsis-induced overexpression of cortical tissue tumor necrosis factor alpha (TNF-α; 51 ± 16% decrease; p = 0.003) and medullary Thr-495 phosphorylation of endothelial nitric oxide synthase (eNOS; 63 ± 18% decrease; p = 0.015). CONCLUSIONS In ovine Gram-negative sepsis, renal arterial infusion of tempol prevented renal medullary hypoperfusion and hypoxia and AKI and decreased TNF-α expression and uncoupling of eNOS. However, it did not affect markers of oxidative/nitrosative stress, which were significantly decreased by Gram-negative sepsis.
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Affiliation(s)
- Ashenafi H. Betrie
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthThe University of MelbourneMelbourneVictoriaAustralia
- Translational Neurodegeneration Laboratory, Florey Institute of Neuroscience and Mental HealthThe University of MelbourneMelbourneVictoriaAustralia
| | - Shuai Ma
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthThe University of MelbourneMelbourneVictoriaAustralia
- Division of Nephrology, Shanghai Ninth People's HospitalShanghai Jiaotong University School of MedicineShanghaiChina
| | - Connie P. C. Ow
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthThe University of MelbourneMelbourneVictoriaAustralia
| | - Rachel M. Peiris
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthThe University of MelbourneMelbourneVictoriaAustralia
| | - Roger G. Evans
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthThe University of MelbourneMelbourneVictoriaAustralia
- Biomedicine Discovery Institute and Department of PhysiologyMonash UniversityMelbourneVictoriaAustralia
| | - Scott Ayton
- Translational Neurodegeneration Laboratory, Florey Institute of Neuroscience and Mental HealthThe University of MelbourneMelbourneVictoriaAustralia
| | - Darius J. R. Lane
- Translational Neurodegeneration Laboratory, Florey Institute of Neuroscience and Mental HealthThe University of MelbourneMelbourneVictoriaAustralia
| | - Adam Southon
- Translational Neurodegeneration Laboratory, Florey Institute of Neuroscience and Mental HealthThe University of MelbourneMelbourneVictoriaAustralia
| | - Simon R. Bailey
- Faculty of Veterinary and Agricultural SciencesThe University of MelbourneMelbourneVictoriaAustralia
| | - Rinaldo Bellomo
- Department of Critical Care, Melbourne Medical SchoolThe University of MelbourneMelbourneVictoriaAustralia
- Australian and New Zealand Intensive Care Research CentreMonash UniversityMelbourneVictoriaAustralia
- Department of Intensive CareAustin HospitalMelbourneVictoriaAustralia
- Department of Intensive CareRoyal Melbourne HospitalMelbourneVictoriaAustralia
| | - Clive N. May
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthThe University of MelbourneMelbourneVictoriaAustralia
- Department of Critical Care, Melbourne Medical SchoolThe University of MelbourneMelbourneVictoriaAustralia
| | - Yugeesh R. Lankadeva
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental HealthThe University of MelbourneMelbourneVictoriaAustralia
- Department of Critical Care, Melbourne Medical SchoolThe University of MelbourneMelbourneVictoriaAustralia
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Waddingham MT, Tsuchimochi H, Sonobe T, Asano R, Jin H, Ow CPC, Schwenke DO, Katare R, Aoyama K, Umetani K, Hoshino M, Uesugi K, Shirai M, Ogo T, Pearson JT. Using Synchrotron Radiation Imaging Techniques to Elucidate the Actions of Hexarelin in the Heart of Small Animal Models. Front Physiol 2022; 12:766818. [PMID: 35126171 PMCID: PMC8814524 DOI: 10.3389/fphys.2021.766818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 11/23/2021] [Indexed: 11/13/2022] Open
Abstract
The majority of the conventional techniques that are utilized for investigating the pathogenesis of cardiovascular disease in preclinical animal models do not permit microlevel assessment of in situ cardiomyocyte and microvascular functions. Therefore, it has been difficult to establish whether cardiac dysfunction in complex multiorgan disease states, such as heart failure with preserved ejection fraction and pulmonary hypertension, have their origins in microvascular dysfunction or rather in the cardiomyocyte. Herein, we describe our approach of utilizing synchrotron radiation microangiography to, first, ascertain whether the growth hormone secretagogue (GHS) hexarelin is a vasodilator in the coronary circulation of normal and anesthetized Sprague-Dawley rats, and next investigate if hexarelin is able to prevent the pathogenesis of right ventricle (RV) dysfunction in pulmonary hypertension in the sugen chronic hypoxia model rat. We show that acute hexarelin administration evokes coronary microvascular dilation through GHS-receptor 1a and nitric oxide, and through endothelium-derived hyperpolarization. Previous work indicated that chronic exogenous administration of ghrelin largely prevented the pathogenesis of pulmonary hypertension in chronic hypoxia and in monocrotaline models. Unexpectedly, chronic hexarelin administration prior to sugen chronic hypoxia did not prevent RV hypertrophy or RV cardiomyocyte relaxation impairment. Small-angle X-ray scattering revealed that super relaxed myosin filaments contributed to diastolic dysfunction, and that length-dependent activation might contribute to sustained contractility of the RV. Thus, synchrotron-based imaging approaches can reveal novel insights into cardiac and coronary functions in vivo.
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Affiliation(s)
- Mark T. Waddingham
- Department of Advanced Medical Research for Pulmonary Hypertension, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Hirotsugu Tsuchimochi
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Japan
| | - Takashi Sonobe
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Japan
| | - Ryotaro Asano
- Department of Advanced Medical Research for Pulmonary Hypertension, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Huiling Jin
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Japan
| | - Connie P. C. Ow
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Japan
| | - Daryl O. Schwenke
- Department of Physiology, School of Biomedical Sciences, Heart Otago, University of Otago, Dunedin, New Zealand
| | - Rajesh Katare
- Department of Physiology, School of Biomedical Sciences, Heart Otago, University of Otago, Dunedin, New Zealand
| | - Kohki Aoyama
- Japan Synchrotron Radiation Research Institute, Harima, Japan
| | - Keiji Umetani
- Japan Synchrotron Radiation Research Institute, Harima, Japan
| | - Masato Hoshino
- Japan Synchrotron Radiation Research Institute, Harima, Japan
| | - Kentaro Uesugi
- Japan Synchrotron Radiation Research Institute, Harima, Japan
| | - Mikiyasu Shirai
- Department of Advanced Medical Research for Pulmonary Hypertension, National Cerebral and Cardiovascular Center, Suita, Japan
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Japan
| | - Takeshi Ogo
- Department of Advanced Medical Research for Pulmonary Hypertension, National Cerebral and Cardiovascular Center, Suita, Japan
| | - James T. Pearson
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Suita, Japan
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
- *Correspondence: James T. Pearson
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Ow CPC, Trask-Marino A, Betrie AH, Evans RG, May CN, Lankadeva YR. Targeting Oxidative Stress in Septic Acute Kidney Injury: From Theory to Practice. J Clin Med 2021; 10:jcm10173798. [PMID: 34501245 PMCID: PMC8432047 DOI: 10.3390/jcm10173798] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [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: 06/29/2021] [Revised: 08/17/2021] [Accepted: 08/23/2021] [Indexed: 12/17/2022] Open
Abstract
Sepsis is the leading cause of acute kidney injury (AKI) and leads to increased morbidity and mortality in intensive care units. Current treatments for septic AKI are largely supportive and are not targeted towards its pathophysiology. Sepsis is commonly characterized by systemic inflammation and increased production of reactive oxygen species (ROS), particularly superoxide. Concomitantly released nitric oxide (NO) then reacts with superoxide, leading to the formation of reactive nitrogen species (RNS), predominantly peroxynitrite. Sepsis-induced ROS and RNS can reduce the bioavailability of NO, mediating renal microcirculatory abnormalities, localized tissue hypoxia and mitochondrial dysfunction, thereby initiating a propagating cycle of cellular injury culminating in AKI. In this review, we discuss the various sources of ROS during sepsis and their pathophysiological interactions with the immune system, microcirculation and mitochondria that can lead to the development of AKI. We also discuss the therapeutic utility of N-acetylcysteine and potential reasons for its efficacy in animal models of sepsis, and its inefficacy in ameliorating oxidative stress-induced organ dysfunction in human sepsis. Finally, we review the pre-clinical studies examining the antioxidant and pleiotropic actions of vitamin C that may be of benefit for mitigating septic AKI, including future implications for clinical sepsis.
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Affiliation(s)
- Connie P. C. Ow
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, Melbourne, VIC 3052, Australia; (C.P.C.O.); (A.T.-M.); (A.H.B.); (R.G.E.); (C.N.M.)
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Osaka 564-8565, Japan
| | - Anton Trask-Marino
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, Melbourne, VIC 3052, Australia; (C.P.C.O.); (A.T.-M.); (A.H.B.); (R.G.E.); (C.N.M.)
| | - Ashenafi H. Betrie
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, Melbourne, VIC 3052, Australia; (C.P.C.O.); (A.T.-M.); (A.H.B.); (R.G.E.); (C.N.M.)
- Melbourne Dementia Research Centre, Florey Institute of Neuroscience and Mental Health, Melbourne, VIC 3052, Australia
| | - Roger G. Evans
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, Melbourne, VIC 3052, Australia; (C.P.C.O.); (A.T.-M.); (A.H.B.); (R.G.E.); (C.N.M.)
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, VIC 3800, Australia
| | - Clive N. May
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, Melbourne, VIC 3052, Australia; (C.P.C.O.); (A.T.-M.); (A.H.B.); (R.G.E.); (C.N.M.)
- Department of Critical Care, Melbourne Medical School, University of Melbourne, Melbourne, VIC 3052, Australia
| | - Yugeesh R. Lankadeva
- Preclinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, Melbourne, VIC 3052, Australia; (C.P.C.O.); (A.T.-M.); (A.H.B.); (R.G.E.); (C.N.M.)
- Department of Critical Care, Melbourne Medical School, University of Melbourne, Melbourne, VIC 3052, Australia
- Correspondence: ; Tel.: +61-3-8344-0417; Fax: +61-3-9035-3107
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Ullah MM, Ow CPC, Evans RG, Hilliard Krause LM. Impact of choice of kinetic model for the determination of transcutaneous FITC-sinistrin clearance in rats with streptozotocin-induced type 1 diabetes. Clin Exp Pharmacol Physiol 2020; 47:1158-1168. [PMID: 32160333 DOI: 10.1111/1440-1681.13301] [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] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 03/08/2020] [Indexed: 11/28/2022]
Abstract
Transcutaneous assessment of fluorescein isothiocyanate (FITC)-sinistrin clearance using an optical device was recently validated for determination of glomerular filtration rate (GFR) in conscious animals. In the current study, we compared four available kinetic models for calculating FITC-sinistrin clearance, to provide further insight into whether the choice of model might influence findings generated using this device. Specifically, we calculated the excretion half-life of FITC-sinistrin (minutes), rate constant (minute-1 ) and GFR indexed to bodyweight in control rats and rats with streptozotocin-induced diabetes across a 4-week experimental period using standard one-compartment (1-COM), two-compartment (2-COM) and three-compartment (3-COM) kinetic models (1-COM), and a three-compartment kinetic model with baseline correction (3-COMB). Glomerular hyperfiltration was detected in STZ-induced diabetic rats with the 2-COM or 3-COMB at day 14 and with the 3-COM at day 3 and 14 after induction of diabetes, but not at any time point using the 1-COM. From a theoretical perspective, we reasoned that the 3-COMB model provides a better estimate of t1/2 than the other models. Linear regression analysis of data generated using the 3-COMB showed a significant relationship between blood glucose and calculated GFR at the day 14 (P = .004) and day 28 (P = .01) time points, and a strong tendency for a relationship at the day 3 time point (P = .06). We conclude that hyperfiltration is an early and sustained characteristic of STZ-induced diabetes in rats. Furthermore, we propose that the 3-COMB model provides the most valid t1/2 for estimation of GFR via transcutaneous detection of FITC-sinistrin clearance.
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Affiliation(s)
- Md Mahbub Ullah
- Cardiovascular Disease Program, Department of Physiology, Biomedicine Discovery Institute, Monash University, Melbourne, Vic., Australia.,Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Connie P C Ow
- Cardiovascular Disease Program, Department of Physiology, Biomedicine Discovery Institute, Monash University, Melbourne, Vic., Australia.,Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
| | - Roger G Evans
- Cardiovascular Disease Program, Department of Physiology, Biomedicine Discovery Institute, Monash University, Melbourne, Vic., Australia
| | - Lucinda M Hilliard Krause
- Cardiovascular Disease Program, Department of Physiology, Biomedicine Discovery Institute, Monash University, Melbourne, Vic., Australia
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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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Ow CPC, Ullah MM, Ngo JP, Sayakkarage A, Evans RG. Detection of cellular hypoxia by pimonidazole adduct immunohistochemistry in kidney disease: methodological pitfalls and their solution. Am J Physiol Renal Physiol 2019; 317:F322-F332. [PMID: 31188031 DOI: 10.1152/ajprenal.00219.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Pimonidazole adduct immunohistochemistry is one of the few available methods for assessing renal tissue hypoxia at the cellular level. It appears to be prone to artifactual false positive staining under some circumstances. Here, we assessed the nature of this false positive staining and, having determined how to avoid it, reexamined the nature of cellular hypoxia in rat models of kidney disease. When a mouse-derived anti-pimonidazole primary antibody was used, two types of staining were observed. First, there was diffuse staining of the cytoplasm of tubular epithelial cells, which was largely absent when the primary antibody was omitted from the incubation protocol or in tissues known not to contain pimonidazole adducts. Second, there was staining of the apical membranes of tubular epithelial cells, debris within the lumen of renal tubules, including tubular casts, and the interstitium; this latter staining was present even when the primary antibody was omitted from the incubation protocol. Such false positive staining was particularly prominent in acutely injured kidneys. It could not be avoided by preincubation of sections with a mouse IgG blocking reagent. Furthermore, preadsorption of the secondary antibody against rat Ig abolished all staining; however, when a rabbit-derived polyclonal anti-pimonidazole primary antibody was used, the false positive staining was largely avoided. Using this method, we confirmed the presence of hypoxia, localized mainly to the tubular epithelium, in the acute phase of severe renal ischemia-reperfusion injury, adenine-induced chronic kidney disease, and polycystic kidney disease. We conclude that this new method provides improved detection of renal cellular hypoxia.
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Affiliation(s)
- Connie P C Ow
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University , Melbourne, Victoria , Australia
| | - Md Mahbub Ullah
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University , Melbourne, Victoria , Australia
| | - Jennifer P Ngo
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University , Melbourne, Victoria , Australia
| | - Adheeshee Sayakkarage
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University , Melbourne, Victoria , Australia
| | - Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University , Melbourne, Victoria , Australia
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9
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Abstract
The limited spatial and temporal resolution of available methods for quantifying renal tissue oxygen tension is a major impediment to identification of the roles of renal hypoxia in kidney diseases. Intravital phosphorescence lifetime imaging microscopy allows cellular oxygen tension in the renal cortex of live animals to be resolved to the level of individual tubular cross-sections. This paves the way for future investigations of the spatial relationships between cellular hypoxia and pathophysiological events in kidney disease.
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Affiliation(s)
- Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia.
| | - Connie P C Ow
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia
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10
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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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11
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Hilliard LM, Colafella KMM, Bulmer LL, Puelles VG, Singh RR, Ow CPC, Gaspari T, Drummond GR, Evans RG, Vinh A, Denton KM. Chronic recurrent dehydration associated with periodic water intake exacerbates hypertension and promotes renal damage in male spontaneously hypertensive rats. Sci Rep 2016; 6:33855. [PMID: 27653548 PMCID: PMC5032121 DOI: 10.1038/srep33855] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 09/05/2016] [Indexed: 01/12/2023] Open
Abstract
Epidemiological evidence links recurrent dehydration associated with periodic water intake with chronic kidney disease (CKD). However, minimal attention has been paid to the long-term impact of periodic water intake on the progression of CKD and underlying mechanisms involved. Therefore we investigated the chronic effects of recurrent dehydration associated with periodic water restriction on arterial pressure and kidney function and morphology in male spontaneously hypertensive rats (SHR). Arterial pressure increased and glomerular filtration rate decreased in water-restricted SHR. This was observed in association with cyclic changes in urine osmolarity, indicative of recurrent dehydration. Additionally, water-restricted SHR demonstrated greater renal fibrosis and an imbalance in favour of pro-inflammatory cytokine-producing renal T cells compared to their control counterparts. Furthermore, urinary NGAL levels were greater in water-restricted than control SHR. Taken together, our results provide significant evidence that recurrent dehydration associated with chronic periodic drinking hastens the progression of CKD and hypertension, and suggest a potential role for repetitive bouts of acute renal injury driving renal inflammatory processes in this setting. Further studies are required to elucidate the specific pathways that drive the progression of recurrent dehydration-induced kidney disease.
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Affiliation(s)
- Lucinda M Hilliard
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, 3800, Australia
| | - Katrina M Mirabito Colafella
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, 3800, Australia
| | - Louise L Bulmer
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, 3800, Australia
| | - Victor G Puelles
- Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria, 3800, Australia
| | - Reetu R Singh
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, 3800, Australia
| | - Connie P C Ow
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, 3800, Australia
| | - Tracey Gaspari
- Department of Pharmacology, Monash University, Melbourne, Victoria, 3800 Australia
| | - Grant R Drummond
- Department of Pharmacology, Monash University, Melbourne, Victoria, 3800 Australia
| | - Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, 3800, Australia
| | - Antony Vinh
- Department of Pharmacology, Monash University, Melbourne, Victoria, 3800 Australia
| | - Kate M Denton
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, 3800, Australia
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12
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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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13
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Sgouralis I, Kett MM, Ow CPC, Abdelkader A, Layton AT, Gardiner BS, Smith DW, Lankadeva YR, Evans RG. Bladder urine oxygen tension for assessing renal medullary oxygenation in rabbits: experimental and modeling studies. Am J Physiol Regul Integr Comp Physiol 2016; 311:R532-44. [PMID: 27385734 DOI: 10.1152/ajpregu.00195.2016] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 07/02/2016] [Indexed: 11/22/2022]
Abstract
Oxygen tension (Po2) of urine in the bladder could be used to monitor risk of acute kidney injury if it varies with medullary Po2 Therefore, we examined this relationship and characterized oxygen diffusion across walls of the ureter and bladder in anesthetized rabbits. A computational model was then developed to predict medullary Po2 from bladder urine Po2 Both intravenous infusion of [Phe(2),Ile(3),Orn(8)]-vasopressin and infusion of N(G)-nitro-l-arginine reduced urinary Po2 and medullary Po2 (8-17%), yet had opposite effects on renal blood flow and urine flow. Changes in bladder urine Po2 during these stimuli correlated strongly with changes in medullary Po2 (within-rabbit r(2) = 0.87-0.90). Differences in the Po2 of saline infused into the ureter close to the kidney could be detected in the bladder, although this was diminished at lesser ureteric flow. Diffusion of oxygen across the wall of the bladder was very slow, so it was not considered in the computational model. The model predicts Po2 in the pelvic ureter (presumed to reflect medullary Po2) from known values of bladder urine Po2, urine flow, and arterial Po2 Simulations suggest that, across a physiological range of urine flow in anesthetized rabbits (0.1-0.5 ml/min for a single kidney), a change in bladder urine Po2 explains 10-50% of the change in pelvic urine/medullary Po2 Thus, it is possible to infer changes in medullary Po2 from changes in urinary Po2, so urinary Po2 may have utility as a real-time biomarker of risk of acute kidney injury.
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Affiliation(s)
- Ioannis Sgouralis
- National Institute for Mathematical and Biological Synthesis, University of Tennessee, Knoxville, Tennessee
| | - Michelle M Kett
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia
| | - Connie P C Ow
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia
| | - Amany Abdelkader
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia
| | - Anita T Layton
- Department of Mathematics, Duke University, Durham, North Carolina
| | - Bruce S Gardiner
- School of Engineering and Information Technology, Murdoch University, Perth, Western Australia
| | - David W Smith
- School of Computer Science and Software Engineering, The University of Western Australia, Perth, Western Australia; and
| | - Yugeesh R Lankadeva
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia;
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14
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Abstract
A relative deficiency in kidney oxygenation, i.e., renal hypoxia, may contribute to the initiation and progression of acute and chronic kidney disease. A critical barrier to investigate this is the lack of methods allowing measurement of the partial pressure of oxygen in kidney tissue for long periods in vivo. We have developed, validated, and tested a novel telemetric method that can do this. Here we provide details on the calibration, implantation, implementation for data recording, and reuse of this telemetry-based technology for measurement of medullary tissue oxygen tension in conscious, unrestrained rats. This technique provides an important additional tool for investigating the impact of renal hypoxia in biology and pathophysiology.
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Affiliation(s)
- Maarten P Koeners
- School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK.
- Department of Physiology, Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
- Department of Nephrology, University Medical Centre Utrecht, Utrecht, The Netherlands.
| | - Connie P C Ow
- Department of Physiology, Monash University, Melbourne, VIC, Australia
| | - David M Russell
- Department of Physiology, Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
- Millar Ltd, Auckland, New Zealand
| | - Roger G Evans
- Department of Physiology, Monash University, Melbourne, VIC, Australia
| | - Simon C Malpas
- Department of Physiology, Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
- Millar Ltd, Auckland, New Zealand
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15
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Abstract
A relative deficiency in kidney oxygenation, i.e., renal hypoxia, may contribute to the initiation and progression of acute and chronic kidney disease. A critical barrier to investigate this is the lack of methods allowing measurement of the partial pressure of oxygen in kidney tissue for long periods in vivo. We have developed, validated, and tested a novel telemetric method that can do this. Here we provide details on the calibration, implantation, implementation for data recording, and reuse of this telemetry-based technology for measurement of medullary tissue oxygen tension in conscious, unrestrained rats. This technique provides an important additional tool for investigating the impact of renal hypoxia in biology and pathophysiology.
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Affiliation(s)
- Maarten P Koeners
- School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK.
- Department of Physiology, Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
- Department of Nephrology, University Medical Centre Utrecht, Utrecht, The Netherlands.
| | - Connie P C Ow
- Department of Physiology, Monash University, Melbourne, VIC, Australia
| | - David M Russell
- Department of Physiology, Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
- Millar Ltd, Auckland, New Zealand
| | - Roger G Evans
- Department of Physiology, Monash University, Melbourne, VIC, Australia
| | - Simon C Malpas
- Department of Physiology, Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
- Millar Ltd, Auckland, New Zealand
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16
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Affiliation(s)
- Roger G. Evans
- Department of Physiology, Monash University, Melbourne, Australia; and
| | - Connie P. C. Ow
- Department of Physiology, Monash University, Melbourne, Australia; and
| | - Peter Bie
- Department of Physiology, Monash University, Melbourne, Australia; and
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
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17
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Ow CPC, Abdelkader A, Hilliard LM, Phillips JK, Evans RG. Determinants of renal tissue hypoxia in a rat model of polycystic kidney disease. Am J Physiol Regul Integr Comp Physiol 2014; 307:R1207-15. [DOI: 10.1152/ajpregu.00202.2014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Renal tissue oxygen tension (Po2) and its determinants have not been quantified in polycystic kidney disease (PKD). Therefore, we measured kidney tissue Po2 in the Lewis rat model of PKD (LPK) and in Lewis control rats. We also determined the relative contributions of altered renal oxygen delivery and consumption to renal tissue hypoxia in LPK rats. Po2 of the superficial cortex of 11- to 13-wk-old LPK rats, measured by Clark electrode with the rat under anesthesia, was higher within the cysts (32.8 ± 4.0 mmHg) than the superficial cortical parenchyma (18.3 ± 3.5 mmHg). Po2 in the superficial cortical parenchyma of Lewis rats was 2.5-fold greater (46.0 ± 3.1 mmHg) than in LPK rats. At each depth below the cortical surface, tissue Po2 in LPK rats was approximately half that in Lewis rats. Renal blood flow was 60% less in LPK than in Lewis rats, and arterial hemoglobin concentration was 57% less, so renal oxygen delivery was 78% less. Renal venous Po2 was 38% less in LPK than Lewis rats. Sodium reabsorption was 98% less in LPK than Lewis rats, but renal oxygen consumption did not significantly differ between the two groups. Thus, in this model of PKD, kidney tissue is severely hypoxic, at least partly because of deficient renal oxygen delivery. Nevertheless, the observation of similar renal oxygen consumption, despite markedly less sodium reabsorption, in the kidneys of LPK compared with Lewis rats, indicates the presence of inappropriately high oxygen consumption in the polycystic kidney.
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Affiliation(s)
- Connie P. C. Ow
- Department of Physiology Monash University, Melbourne, Australia; and
| | - Amany Abdelkader
- Department of Physiology Monash University, Melbourne, Australia; and
| | | | | | - Roger G. Evans
- Department of Physiology Monash University, Melbourne, Australia; and
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18
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Abdelkader A, Ho J, Ow CPC, Eppel GA, Rajapakse NW, Schlaich MP, Evans RG. Renal oxygenation in acute renal ischemia-reperfusion injury. Am J Physiol Renal Physiol 2014; 306:F1026-38. [PMID: 24598805 DOI: 10.1152/ajprenal.00281.2013] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Tissue hypoxia has been demonstrated, in both the renal cortex and medulla, during the acute phase of reperfusion after ischemia induced by occlusion of the aorta upstream from the kidney. However, there are also recent clinical observations indicating relatively well preserved oxygenation in the nonfunctional transplanted kidney. To test whether severe acute kidney injury can occur in the absence of widespread renal tissue hypoxia, we measured cortical and inner medullary tissue Po2 as well as total renal O2 delivery (Do2) and O2 consumption (Vo2) during the first 2 h of reperfusion after 60 min of occlusion of the renal artery in anesthetized rats. To perform this experiment, we used a new method for measuring kidney Do2 and Vo2 that relies on implantation of fluorescence optodes in the femoral artery and renal vein. We were unable to detect reductions in renal cortical or inner medullary tissue Po2 during reperfusion after ischemia localized to the kidney. This is likely explained by the observation that Vo2 (-57%) was reduced by at least as much as Do2 (-45%), due to a large reduction in glomerular filtration (-94%). However, localized tissue hypoxia, as evidence by pimonidazole adduct immunohistochemistry, was detected in kidneys subjected to ischemia and reperfusion, particularly in, but not exclusive to, the outer medulla. Thus, cellular hypoxia, particularly in the outer medulla, may still be present during reperfusion even when reductions in tissue Po2 are not detected in the cortex or inner medulla.
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Affiliation(s)
- Amany Abdelkader
- Dept. of Physiology, PO Box 13F, Monash Univ., Victoria 3800, Australia.
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19
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Evans RG, Harrop GK, Ngo JP, Ow CPC, O'Connor PM. Basal renal O2 consumption and the efficiency of O2 utilization for Na+ reabsorption. Am J Physiol Renal Physiol 2014; 306:F551-60. [PMID: 24431201 DOI: 10.1152/ajprenal.00473.2013] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined how the presence of a fixed level of basal renal O2 consumption (Vo2(basal); O2 used for processes independent of Na(+) transport) confounds the utility of the ratio of Na(+) reabsorption (TNa(+)) to total renal Vo2 (Vo2(total)) as an index of the efficiency of O2 utilization for TNa(+). We performed a systematic review and additional experiments in anesthetized rabbits to obtain the best possible estimate of the fractional contribution of Vo2(basal) to Vo2(total) under physiological conditions (basal percent renal Vo2). Estimates of basal percent renal Vo2 from 24 studies varied from 0% to 81.5%. Basal percent renal Vo2 varied with the fractional excretion of Na(+) (FENa(+)) in the 14 studies in which FENa(+) was measured under control conditions. Linear regression analysis predicted a basal percent renal Vo2 of 12.7-16.5% when FENa(+) = 1% (r(2) = 0.48, P = 0.001). Experimentally induced changes in TNa(+) altered TNa(+)/Vo2(total) in a manner consistent with theoretical predictions. We conclude that, because Vo2(basal) represents a significant proportion of Vo2(total), TNa(+)/Vo2(total) can change markedly when TNa(+) itself changes. Therefore, caution should be taken when TNa(+)/Vo2(total) is interpreted as a measure of the efficiency of O2 utilization for TNa(+), particularly under experimental conditions where TNa(+) or Vo2(total) changes.
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Affiliation(s)
- Roger G Evans
- Dept. of Physiology, PO Box 13F, Monash Univ., Victoria 3800, Australia.
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20
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Koeners MP, Ow CPC, Russell DM, Abdelkader A, Eppel GA, Ludbrook J, Malpas SC, Evans RG. Telemetry-based oxygen sensor for continuous monitoring of kidney oxygenation in conscious rats. Am J Physiol Renal Physiol 2013; 304:F1471-80. [DOI: 10.1152/ajprenal.00662.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The precise roles of hypoxia in the initiation and progression of kidney disease remain unresolved. A major technical limitation has been the absence of methods allowing long-term measurement of kidney tissue oxygen tension (Po2) in unrestrained animals. We developed a telemetric method for the measurement of kidney tissue Po2 in unrestrained rats, using carbon paste electrodes (CPEs). After acute implantation in anesthetized rats, tissue Po2 measured by CPE-telemetry in the inner cortex and medulla was in close agreement with that provided by the “gold standard” Clark electrode. The CPE-telemetry system could detect small changes in renal tissue Po2 evoked by mild hypoxemia. In unanesthetized rats, CPE-telemetry provided stable measurements of medullary tissue Po2 over days 5− 19 after implantation. It also provided reproducible responses to systemic hypoxia and hyperoxia over this time period. There was little evidence of fibrosis or scarring after 3 wk of electrode implantation. However, because medullary Po2 measured by CPE-telemetry was greater than that documented from previous studies in anesthetized animals, this method is presently best suited for monitoring relative changes rather than absolute values. Nevertheless, this new technology provides, for the first time, the opportunity to examine the temporal relationships between tissue hypoxia and the progression of renal disease.
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Affiliation(s)
- Maarten P. Koeners
- Department of Physiology, Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
- Nephrology, University Medical Centre Utrecht, Utrecht, Netherlands
| | - Connie P. C. Ow
- Department of Physiology, Monash University, Melbourne, Australia
| | - David M. Russell
- Department of Physiology, Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
- Millar Instruments, Auckland, New Zealand; and
| | - Amany Abdelkader
- Department of Physiology, Monash University, Melbourne, Australia
| | | | - John Ludbrook
- Department of Surgery, University of Melbourne, Melbourne, Australia
| | - Simon C. Malpas
- Department of Physiology, Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
- Millar Instruments, Auckland, New Zealand; and
| | - Roger G. Evans
- Department of Physiology, Monash University, Melbourne, Australia
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