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Bankir L, Figueres L, Prot-Bertoye C, Bouby N, Crambert G, Pratt JH, Houillier P. Medullary and cortical thick ascending limb: similarities and differences. Am J Physiol Renal Physiol 2020; 318:F422-F442. [DOI: 10.1152/ajprenal.00261.2019] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The thick ascending limb of the loop of Henle (TAL) is the first segment of the distal nephron, extending through the whole outer medulla and cortex, two regions with different composition of the peritubular environment. The TAL plays a critical role in the control of NaCl, water, acid, and divalent cation homeostasis, as illustrated by the consequences of the various monogenic diseases that affect the TAL. It delivers tubular fluid to the distal convoluted tubule and thereby affects the function of the downstream tubular segments. The TAL is commonly considered as a whole. However, many structural and functional differences exist between its medullary and cortical parts. The present review summarizes the available data regarding the similarities and differences between the medullary and cortical parts of the TAL. Both subsegments reabsorb NaCl and have high Na+-K+-ATPase activity and negligible water permeability; however, they express distinct isoforms of the Na+-K+-2Cl−cotransporter at the apical membrane. Ammonia and bicarbonate are mostly reabsorbed in the medullary TAL, whereas Ca2+and Mg2+are mostly reabsorbed in the cortical TAL. The peptidic hormone receptors controlling transport in the TAL are not homogeneously expressed along the cortical and medullary TAL. Besides this axial heterogeneity, structural and functional differences are also apparent between species, which underscores the link between properties and role of the TAL under various environments.
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Affiliation(s)
- Lise Bankir
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France
- CNRS ERL 8228-Laboratoire de Physiologie Rénale et Tubulopathies, Paris, France
| | - Lucile Figueres
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France
- CNRS ERL 8228-Laboratoire de Physiologie Rénale et Tubulopathies, Paris, France
| | - Caroline Prot-Bertoye
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France
- CNRS ERL 8228-Laboratoire de Physiologie Rénale et Tubulopathies, Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Département de Physiologie, Paris, France
- Centre de Référence des Maladies Rénales Héréditaires de l’Enfant et de l’Adulte, Paris, France
| | - Nadine Bouby
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France
- CNRS ERL 8228-Laboratoire de Physiologie Rénale et Tubulopathies, Paris, France
| | - Gilles Crambert
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France
- CNRS ERL 8228-Laboratoire de Physiologie Rénale et Tubulopathies, Paris, France
| | - J. Howard Pratt
- Division of Endocrinology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Pascal Houillier
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France
- CNRS ERL 8228-Laboratoire de Physiologie Rénale et Tubulopathies, Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Département de Physiologie, Paris, France
- Centre de Référence des Maladies Rénales Héréditaires de l’Enfant et de l’Adulte, Paris, France
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Lee CJ, Gardiner BS, Evans RG, Smith DW. A model of oxygen transport in the rat renal medulla. Am J Physiol Renal Physiol 2018; 315:F1787-F1811. [DOI: 10.1152/ajprenal.00363.2018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The renal medulla is prone to hypoxia. Medullary hypoxia is postulated to be a leading cause of acute kidney injury, so there is considerable interest in predicting the oxygen tension in the medulla. Therefore we have developed a computational model for blood and oxygen transport within a physiologically normal rat renal medulla, using a multilevel modeling approach. For the top-level model we use the theory of porous media and advection-dispersion transport through a realistic three-dimensional representation of the medulla’s gross anatomy to describe blood flow and oxygen transport throughout the renal medulla. For the lower-level models, we employ two-dimensional reaction-diffusion models describing the distribution of oxygen through tissue surrounding the vasculature. Steady-state model predictions at the two levels are satisfied simultaneously, through iteration between the levels. The computational model was validated by simulating eight sets of experimental data regarding renal oxygenation in rats (using 4 sets of control groups and 4 sets of treatment groups, described in 4 independent publications). Predicted medullary tissue oxygen tension or microvascular oxygen tension for control groups and for treatment groups that underwent moderate perturbation in hemodynamic and renal functions is within ±2 SE values observed experimentally. Diffusive shunting between descending and ascending vasa recta is predicted to be only 3% of the oxygen delivered. The validation tests confirm that the computational model is robust and capable of capturing the behavior of renal medullary oxygenation in both normal and early-stage pathological states in the rat.
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Affiliation(s)
- Chang-Joon Lee
- School of Engineering and Information Technology, Murdoch University, Perth, Western Australia, Australia
- Faculty of Engineering and Mathematical Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Bruce S. Gardiner
- School of Engineering and Information Technology, Murdoch University, Perth, Western Australia, Australia
- Faculty of Engineering and Mathematical Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Roger G. Evans
- Cardiovascular Disease Program, Biomedicine Discovery Institute, and Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - David W. Smith
- Faculty of Engineering and Mathematical Sciences, The University of Western Australia, Perth, Western Australia, Australia
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