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Chin K, Cazorla-Bak MP, Liu E, Nghiem L, Zhang Y, Yu J, Wilson DF, Vinogradov SA, Gilbert RE, Connelly KA, Evans RG, Baker AJ, David Mazer C, Hare GMT. Renal microvascular oxygen tension during hyperoxia and acute hemodilution assessed by phosphorescence quenching and excitation with blue and red light. Can J Anaesth 2020; 68:214-225. [PMID: 33174162 DOI: 10.1007/s12630-020-01848-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 08/05/2020] [Accepted: 08/14/2020] [Indexed: 12/13/2022] Open
Abstract
PURPOSE The kidney plays a central physiologic role as an oxygen sensor. Nevertheless, the direct mechanism by which this occurs is incompletely understood. We measured renal microvascular partial pressure of oxygen (PkO2) to determine the impact of clinically relevant conditions that acutely change PkO2 including hyperoxia and hemodilution. METHODS We utilized two-wavelength excitation (red and blue spectrum) of the intravascular phosphorescent oxygen sensitive probe Oxyphor PdG4 to measure renal tissue PO2 in anesthetized rats (2% isoflurane, n = 6) under two conditions of altered arterial blood oxygen content (CaO2): 1) hyperoxia (fractional inspired oxygen 21%, 30%, and 50%) and 2) acute hemodilutional anemia (baseline, 25% and 50% acute hemodilution). The mean arterial blood pressure (MAP), rectal temperature, arterial blood gases (ABGs), and chemistry (radiometer) were measured under each condition. Blue and red light enabled measurement of PkO2 in the superficial renal cortex and deeper cortical and medullary tissue, respectively. RESULTS PkO2 was higher in the superficial renal cortex (~ 60 mmHg, blue light) relative to the deeper renal cortex and outer medulla (~ 45 mmHg, red light). Hyperoxia resulted in a proportional increase in PkO2 values while hemodilution decreased microvascular PkO2 in a linear manner in both superficial and deeper regions of the kidney. In both cases (blue and red light), PkO2 correlated with CaO2 but not with MAP. CONCLUSION The observed linear relationship between CaO2 and PkO2 shows the biological function of the kidney as a quantitative sensor of anemic hypoxia and hyperoxia. A better understanding of the impact of changes in PkO2 may inform clinical practices to improve renal oxygen delivery and prevent acute kidney injury.
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Affiliation(s)
- Kyle Chin
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada
| | - Melina P Cazorla-Bak
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Elaine Liu
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada
| | - Linda Nghiem
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
| | - Yanling Zhang
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
| | - Julie Yu
- Deaprtment of Anesthesia and Perioperative Medicine, Western University, London, ON, Canada
| | - David F Wilson
- Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Richard E Gilbert
- Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada.,Division of Endocrinology, Department of Medicine, St. Michael's Hospital, University of Toronto, Toronto, ON, Canada
| | - Kim A Connelly
- Department of Physiology, University of Toronto, Toronto, ON, Canada.,Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada.,Division of Cardiology, Department of Medicine, St. Michael's Hospital, University of Toronto, Toronto, ON, Canada
| | - Roger G Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Australia
| | - Andrew J Baker
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada.,Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - C David Mazer
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Gregory M T Hare
- Department of Anesthesia, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B 1W8, Canada. .,Department of Physiology, University of Toronto, Toronto, ON, Canada. .,Keenan Research Centre for Biomedical Science in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada.
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Happé CM, de Raaf MA, Rol N, Schalij I, Vonk-Noordegraaf A, Westerhof N, Voelkel NF, de Man FS, Bogaard HJ. Pneumonectomy combined with SU5416 induces severe pulmonary hypertension in rats. Am J Physiol Lung Cell Mol Physiol 2016; 310:L1088-97. [PMID: 27036867 DOI: 10.1152/ajplung.00023.2016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 03/23/2016] [Indexed: 11/22/2022] Open
Abstract
The SU5416 + hypoxia (SuHx) rat model is a commonly used model of severe pulmonary arterial hypertension. While it is known that exposure to hypoxia can be replaced by another type of hit (e.g., ovalbumin sensitization) it is unknown whether abnormal pulmonary blood flow (PBF), which has long been known to invoke pathological changes in the pulmonary vasculature, can replace the hypoxic exposure. Here we studied if a combination of SU5416 administration combined with pneumonectomy (PNx), to induce abnormal PBF in the contralateral lung, is sufficient to induce severe pulmonary arterial hypertension (PAH) in rats. Sprague Dawley rats were subjected to SuPNx protocol (SU5416 + combined with left pneumonectomy) or standard SuHx protocol, and comparisons between models were made at week 2 and 6 postinitiation. Both SuHx and SuPNx models displayed extensive obliterative vascular remodeling leading to an increased right ventricular systolic pressure at week 6 Similar inflammatory response in the lung vasculature of both models was observed alongside increased endothelial cell proliferation and apoptosis. This study describes the SuPNx model, which features severe PAH at 6 wk and could serve as an alternative to the SuHx model. Our study, together with previous studies on experimental models of pulmonary hypertension, shows that the typical histopathological findings of PAH, including obliterative lesions, inflammation, increased cell turnover, and ongoing apoptosis, represent a final common pathway of a disease that can evolve as a consequence of a variety of insults to the lung vasculature.
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Affiliation(s)
- C M Happé
- Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands; Department of Pulmonology, VU University Medical Center, Amsterdam, the Netherlands; and
| | - M A de Raaf
- Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands; Department of Pulmonology, VU University Medical Center, Amsterdam, the Netherlands; and
| | - N Rol
- Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands; Department of Pulmonology, VU University Medical Center, Amsterdam, the Netherlands; and
| | - I Schalij
- Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands; Department of Pulmonology, VU University Medical Center, Amsterdam, the Netherlands; and
| | - A Vonk-Noordegraaf
- Department of Pulmonology, VU University Medical Center, Amsterdam, the Netherlands; and
| | - N Westerhof
- Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - N F Voelkel
- School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia
| | - F S de Man
- Department of Pulmonology, VU University Medical Center, Amsterdam, the Netherlands; and
| | - H J Bogaard
- Department of Pulmonology, VU University Medical Center, Amsterdam, the Netherlands; and
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Darby PJ, Kim N, Hare GMT, Tsui A, Wang Z, Harrington A, Mazer CD. Anemia increases the risk of renal cortical and medullary hypoxia during cardiopulmonary bypass. Perfusion 2013; 28:504-11. [DOI: 10.1177/0267659113490219] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Introduction: Anemia is an independent predictor of acute kidney injury (AKI) following cardiopulmonary bypass (CPB), possibly due to inadequate renal oxygen delivery. The objective of this study was to investigate the effects of CPB and anemia on tissue oxygen tension (pO2) and blood flow in the renal cortex and medulla. Methods: Rats (n=6/group) underwent 1hr of normothermic cardiopulmonary bypass (CPB), with target hemoglobin concentrations (Hb) of 10g/dL (CPB) or 6.5g/dL (anemia-CPB). Renal blood flow (RBF) and tissue PO2 were measured before, during and after 1hr of CPB. To confirm the observed differences in renal cortical and medullary PO2, HIF-1α (ODD) luciferase mice were exposed to 8% O2 (hypoxia) and HIF-1α dependent luminescence was measured in the renal cortex and medulla (n=5). Results: Renal tissue PO2 values decreased initially and returned towards baseline, however, values at the end of CPB. Anemia-CPB resulted in a significant increase in both renal cortical and medullary blood flow, PO2 remained significantly reduced throughout anemia-CPB. Renal medullary HIF-1α-dependent luminescence confirmed a greater degree of hypoxia in the renal medulla. Discussion: During CPB, renal O2 delivery was transiently jeopardized, but recovered after 1hr. Anemia-CPB resulted in a dramatic and sustained reduction in renal cortical and medullary PO2, which suggests an increased risk of renal hypoxic injury with anemia. Conclusion: The clear difference in the degree of hypoxia in the renal cortex and medulla may be useful in understanding the progress of medullary hypoxia during CPB with anemia and the potential development of AKI. Further studies should aim at identifying early markers of medullary hypoxia and potential agents that may decrease the work and O2 consumption in the renal medulla to reduce the risk of hypoxic damage during CPB and anemia.
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Affiliation(s)
- PJ Darby
- Department of Anesthesia, Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
| | - N Kim
- Department of Anesthesia, Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
- Departments of Anesthesia & Physiology, University of Toronto, Toronto, Ontario, Canada
| | - GMT Hare
- Department of Anesthesia, Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
- Departments of Anesthesia & Physiology, University of Toronto, Toronto, Ontario, Canada
| | - A Tsui
- Department of Anesthesia, Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
| | - Z Wang
- Department of Anesthesia, Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
| | - A Harrington
- Department of Anesthesia, Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
| | - CD Mazer
- Department of Anesthesia, Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
- Departments of Anesthesia & Physiology, University of Toronto, Toronto, Ontario, Canada
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