1
|
Guo J, Zhang C, Zhao H, Yan Y, Liu Z. The key mediator of diabetic kidney disease: Potassium channel dysfunction. Genes Dis 2024; 11:101119. [PMID: 38523672 PMCID: PMC10958065 DOI: 10.1016/j.gendis.2023.101119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 06/11/2022] [Accepted: 06/04/2023] [Indexed: 03/26/2024] Open
Abstract
Diabetic kidney disease is a leading cause of end-stage renal disease, making it a global public health concern. The molecular mechanisms underlying diabetic kidney disease have not been elucidated due to its complex pathogenesis. Thus, exploring these mechanisms from new perspectives is the current focus of research concerning diabetic kidney disease. Ion channels are important proteins that maintain the physiological functions of cells and organs. Among ion channels, potassium channels stand out, because they are the most common and important channels on eukaryotic cell surfaces and function as the basis for cell excitability. Certain potassium channel abnormalities have been found to be closely related to diabetic kidney disease progression and genetic susceptibility, such as KATP, KCa, Kir, and KV. In this review, we summarized the roles of different types of potassium channels in the occurrence and development of diabetic kidney disease to discuss whether the development of DKD is due to potassium channel dysfunction and present new ideas for the treatment of DKD.
Collapse
Affiliation(s)
- Jia Guo
- Nephrology Research Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, Henan 450052, China
- Research Center for Kidney Disease, Zhengzhou, Henan 450052, China
| | - Chaojie Zhang
- Nephrology Research Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, Henan 450052, China
- Research Center for Kidney Disease, Zhengzhou, Henan 450052, China
| | - Hui Zhao
- Nephrology Research Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, Henan 450052, China
- Research Center for Kidney Disease, Zhengzhou, Henan 450052, China
| | - Yufan Yan
- Nephrology Research Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, Henan 450052, China
- Research Center for Kidney Disease, Zhengzhou, Henan 450052, China
| | - Zhangsuo Liu
- Nephrology Research Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, Henan 450052, China
- Research Center for Kidney Disease, Zhengzhou, Henan 450052, China
| |
Collapse
|
2
|
Jung HJ, Pham TD, Su XT, Grigore TV, Hoenderop JG, Olauson H, Wall SM, Ellison DH, Welling PA, Al-Qusairi L. Klotho is highly expressed in the chief sites of regulated potassium secretion, and it is stimulated by potassium intake. Sci Rep 2024; 14:10740. [PMID: 38729987 PMCID: PMC11087591 DOI: 10.1038/s41598-024-61481-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 05/06/2024] [Indexed: 05/12/2024] Open
Abstract
Klotho regulates many pathways in the aging process, but it remains unclear how it is physiologically regulated. Because Klotho is synthesized, cleaved, and released from the kidney; activates the chief urinary K+ secretion channel (ROMK) and stimulates urinary K+ secretion, we explored if Klotho protein is regulated by dietary K+ and the potassium-regulatory hormone, Aldosterone. Klotho protein along the nephron was evaluated in humans and in wild-type (WT) mice; and in mice lacking components of Aldosterone signaling, including the Aldosterone-Synthase KO (AS-KO) and the Mineralocorticoid-Receptor KO (MR-KO) mice. We found the specific cells of the distal nephron in humans and mice that are chief sites of regulated K+ secretion have the highest Klotho protein expression along the nephron. WT mice fed K+-rich diets increased Klotho expression in these cells. AS-KO mice exhibit normal Klotho under basal conditions but could not upregulate Klotho in response to high-K+ intake in the K+-secreting cells. Similarly, MR-KO mice exhibit decreased Klotho protein expression. Together, i) Klotho is highly expressed in the key sites of regulated K+ secretion in humans and mice, ii) In mice, K+-rich diets increase Klotho expression specifically in the potassium secretory cells of the distal nephron, iii) Aldosterone signaling is required for Klotho response to high K+ intake.
Collapse
Affiliation(s)
- Hyun Jun Jung
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Truyen D Pham
- Department of Nephrology, Emory University School of Medicine, Atlanta, GA, USA
| | - Xiao-Tong Su
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, USA
| | - Teodora Veronica Grigore
- Department of Medical BioSciences, Radboud Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G Hoenderop
- Department of Medical BioSciences, Radboud Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Hannes Olauson
- Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
| | - Susan M Wall
- Department of Nephrology, Emory University School of Medicine, Atlanta, GA, USA
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, USA
| | - Paul A Welling
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Lama Al-Qusairi
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| |
Collapse
|
3
|
Stadt MM, Layton AT. A modeling analysis of whole body potassium regulation on a high-potassium diet: proximal tubule and tubuloglomerular feedback effects. Am J Physiol Regul Integr Comp Physiol 2024; 326:R401-R415. [PMID: 38465401 DOI: 10.1152/ajpregu.00283.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 02/15/2024] [Accepted: 03/05/2024] [Indexed: 03/12/2024]
Abstract
Potassium (K+) is an essential electrolyte that plays a key role in many physiological processes, including mineralcorticoid action, systemic blood-pressure regulation, and hormone secretion and action. Indeed, maintaining K+ balance is critical for normal cell function, as too high or too low K+ levels can have serious and potentially deadly health consequences. K+ homeostasis is achieved by an intricate balance between the intracellular and extracellular fluid as well as balance between K+ intake and excretion. This is achieved via the coordinated actions of regulatory mechanisms such as the gastrointestinal feedforward effect, insulin and aldosterone upregulation of Na+-K+-ATPase uptake, and hormone and electrolyte impacts on renal K+ handling. We recently developed a mathematical model of whole body K+ regulation to unravel the individual impacts of these regulatory mechanisms. In this study, we extend our mathematical model to incorporate recent experimental findings that showed decreased fractional proximal tubule reabsorption under a high-K+ diet. We conducted model simulations and sensitivity analyses to investigate how these renal alterations impact whole body K+ regulation. Model predictions quantify the sensitivity of K+ regulation to various levels of proximal tubule K+ reabsorption adaptation and tubuloglomerular feedback. Our results suggest that the reduced proximal tubule K+ reabsorption under a high-K+ diet could achieve K+ balance in isolation, but the resulting tubuloglomerular feedback reduces filtration rate and thus K+ excretion.NEW & NOTEWORTHY Potassium homeostasis is maintained in the body by a complex system of regulatory mechanisms. This system, when healthy, maintains a small extracellular potassium concentration, despite large fluctuations of dietary potassium. The complexities of the system make this problem well suited for investigation with mathematical modeling. In this study, we extend our mathematical model to consider recent experimental results on renal potassium handling on a high potassium diet and investigate the impacts from a whole body perspective.
Collapse
Affiliation(s)
- Melissa M Stadt
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
| | - Anita T Layton
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
- Cheriton School of Computer Science, University of Waterloo, Waterloo, Ontario, Canada
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
- Department of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada
| |
Collapse
|
4
|
Xu X, Zeng L, Jha V, Cobb LK, Shibuya K, Appel LJ, Neal B, Schutte AE. Potassium-Enriched Salt Substitutes: A Review of Recommendations in Clinical Management Guidelines. Hypertension 2024; 81:400-414. [PMID: 38284271 PMCID: PMC10863666 DOI: 10.1161/hypertensionaha.123.21343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2024]
Abstract
Excess dietary sodium intake and insufficient dietary potassium intake are both well-established risk factors for hypertension. Despite some successful initiatives, efforts to control hypertension by improving dietary intake have largely failed because the changes required are mostly too hard to implement. Consistent recent data from randomized controlled trials show that potassium-enriched, sodium-reduced salt substitutes are an effective option for improving consumption levels and reducing blood pressure and the rates of cardiovascular events and deaths. Yet, salt substitutes are inconsistently recommended and rarely used. We sought to define the extent to which evidence about the likely benefits and harms of potassium-enriched salt substitutes has been incorporated into clinical management by systematically searching guidelines for the management of hypertension or chronic kidney disease. We found incomplete and inconsistent recommendations about the use of potassium-enriched salt substitutes in the 32 hypertension and 14 kidney guidelines that we reviewed. Discussion among the authors identified the possibility of updating clinical guidelines to provide consistent advice about the use of potassium-enriched salt for hypertension control. Draft wording was chosen to commence debate and progress consensus building: strong recommendation for patients with hypertension-potassium-enriched salt with a composition of 75% sodium chloride and 25% potassium chloride should be recommended to all patients with hypertension, unless they have advanced kidney disease, are using a potassium supplement, are using a potassium-sparing diuretic, or have another contraindication. We strongly encourage clinical guideline bodies to review their recommendations about the use of potassium-enriched salt substitutes at the earliest opportunity.
Collapse
Affiliation(s)
- Xiaoyue Xu
- School of Population Health (X.X., L.Z., A.E.S.), University of New South Wales Sydney, Kensington, Australia
- The George Institute for Global Health (X.X., B.N., A.E.S.), University of New South Wales Sydney, Kensington, Australia
| | - Ling Zeng
- School of Population Health (X.X., L.Z., A.E.S.), University of New South Wales Sydney, Kensington, Australia
| | - Vivekanand Jha
- The George Institute for Global Health, University of New South Wales, New Delhi, India (V.J.)
- School of Public Health, Imperial College London, United Kingdom (V.J., B.N.)
- Prasanna School of Public Health, Manipal Academy of Higher Education, India (V.J.)
| | | | | | - Lawrence J. Appel
- Department of Epidemiology, Bloomberg School of Public Health and Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University, Baltimore, MD (L.J.A.)
| | - Bruce Neal
- The George Institute for Global Health (X.X., B.N., A.E.S.), University of New South Wales Sydney, Kensington, Australia
- School of Public Health, Imperial College London, United Kingdom (V.J., B.N.)
| | - Aletta E. Schutte
- School of Population Health (X.X., L.Z., A.E.S.), University of New South Wales Sydney, Kensington, Australia
- The George Institute for Global Health (X.X., B.N., A.E.S.), University of New South Wales Sydney, Kensington, Australia
- Hypertension in Africa Research Team, Medical Research Council Unit for Hypertension and Cardiovascular Disease, North-West University, Potchefstroom, South Africa (A.E.S.)
- Department of Paediatrics, Medical Research Council/Wits Developmental Pathways for Health Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa (A.E.S)
| |
Collapse
|
5
|
Demirci M, Hinton A, Kirabo A. Dendritic cell epithelial sodium channel induced inflammation and salt-sensitive hypertension. Curr Opin Nephrol Hypertens 2024; 33:145-153. [PMID: 38180118 PMCID: PMC10842661 DOI: 10.1097/mnh.0000000000000963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024]
Abstract
PURPOSE OF REVIEW Salt sensitivity of blood pressure (SSBP) is an independent risk factor for cardiovascular disease. Epithelial sodium channel (ENaC) plays a critical role in renal electrolyte and volume regulation and has been implicated in the pathogenesis of SSBP. This review describes recent advances regarding the role of ENaC-dependent inflammation in the development of SSBP. RECENT FINDINGS We recently found that sodium enters dendritic cells via ENaC, a process regulated by serum/glucocorticoid-regulated kinase 1 and epoxyeicosatrienoic acid 14,15. Sodium entry activates NADPH oxidase, leading to the production of isolevuglandins (IsoLGs). IsoLGs adduct self-proteins to form neoantigens in dendritic cells that activate T cells and result in the release of cytokines promoting sodium retention, kidney damage, and endothelial dysfunction in SSBP. Additionally, we described a novel mechanistic pathway involving ENaC and IsoLG-dependent NLRP3 inflammasome activation. These findings hold promise for the development of novel diagnostic biomarkers and therapeutic options for SSBP. SUMMARY The exact mechanisms underlying SSBP remain elusive. Recent advances in understanding the extrarenal role of ENaC have opened a new perspective, and further research efforts should focus on understanding the link between ENaC, inflammation, and SSBP.
Collapse
Affiliation(s)
- Mert Demirci
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center
| | - Antentor Hinton
- Department of Molecular Physiology and Biophysics, Vanderbilt University
| | - Annet Kirabo
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center
- Vanderbilt Center for Immunobiology
- Vanderbilt Institute for Infection, Immunology and Inflammation
- Vanderbilt Institute for Global Health, Nashville, Tennessee, USA
| |
Collapse
|
6
|
MacLaughlin HL, McAuley E, Fry J, Pacheco E, Moran N, Morgan K, McGuire L, Conley M, Johnson DW, Ratanjee SK, Mason B. Re-Thinking Hyperkalaemia Management in Chronic Kidney Disease-Beyond Food Tables and Nutrition Myths: An Evidence-Based Practice Review. Nutrients 2023; 16:3. [PMID: 38201833 PMCID: PMC10780359 DOI: 10.3390/nu16010003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 12/03/2023] [Accepted: 12/13/2023] [Indexed: 01/12/2024] Open
Abstract
Potassium dysregulation can be life-threatening. Dietary potassium modification is a management strategy for hyperkalaemia. However, a 2017 review for clinical guidelines found no trials evaluating dietary restriction for managing hyperkalaemia in chronic kidney disease (CKD). Evidence regarding dietary hyperkalaemia management was reviewed and practice recommendations disseminated. A literature search using terms for potassium, hyperkalaemia, and CKD was undertaken from 2018 to October 2022. Researchers extracted data, discussed findings, and formulated practice recommendations. A consumer resource, a clinician education webinar, and workplace education sessions were developed. Eighteen studies were included. Observational studies found no association between dietary and serum potassium in CKD populations. In two studies, 40-60 mmol increases in dietary/supplemental potassium increased serum potassium by 0.2-0.4 mmol/L. No studies examined lowering dietary potassium as a therapeutic treatment for hyperkalaemia. Healthy dietary patterns were associated with improved outcomes and may predict lower serum potassium, as dietary co-factors may support potassium shifts intracellularly, and increase excretion through the bowel. The resource recommended limiting potassium additives, large servings of meat and milk, and including high-fibre foods: wholegrains, fruits, and vegetables. In seven months, the resource received > 3300 views and the webinar > 290 views. This review highlights the need for prompt review of consumer resources, hospital diets, and health professionals' knowledge.
Collapse
Affiliation(s)
- Helen L. MacLaughlin
- Nutrition Research Collaborative, Department of Dietetics and Foodservices, Royal Brisbane and Women’s Hospital, Herston, QLD 4029, Australia (E.P.)
- School of Exercise & Nutrition Sciences, Queensland University of Technology, Brisbane, QLD 4059, Australia
| | - Erynn McAuley
- Nutrition Research Collaborative, Department of Dietetics and Foodservices, Royal Brisbane and Women’s Hospital, Herston, QLD 4029, Australia (E.P.)
- School of Exercise & Nutrition Sciences, Queensland University of Technology, Brisbane, QLD 4059, Australia
| | - Jessica Fry
- Nutrition Research Collaborative, Department of Dietetics and Foodservices, Royal Brisbane and Women’s Hospital, Herston, QLD 4029, Australia (E.P.)
| | - Elissa Pacheco
- Nutrition Research Collaborative, Department of Dietetics and Foodservices, Royal Brisbane and Women’s Hospital, Herston, QLD 4029, Australia (E.P.)
| | - Natalie Moran
- Nutrition Research Collaborative, Department of Dietetics and Foodservices, Royal Brisbane and Women’s Hospital, Herston, QLD 4029, Australia (E.P.)
| | - Kate Morgan
- Nutrition Research Collaborative, Department of Dietetics and Foodservices, Royal Brisbane and Women’s Hospital, Herston, QLD 4029, Australia (E.P.)
| | - Lisa McGuire
- Nutrition Research Collaborative, Department of Dietetics and Foodservices, Royal Brisbane and Women’s Hospital, Herston, QLD 4029, Australia (E.P.)
| | - Marguerite Conley
- School of Exercise & Nutrition Sciences, Queensland University of Technology, Brisbane, QLD 4059, Australia
- Nutrition and Dietetics Department, Princess Alexandra Hospital, Woolloongabba, QLD 4102, Australia
| | - David W. Johnson
- Department of Kidney and Transplant Services, Division of Medicine, Princess Alexandra Hospital, Woolloongabba, QLD 4102, Australia
- Centre for Health Services Research, The University of Queensland, St. Lucia, QLD 4067, Australia
| | - Sharad K. Ratanjee
- Kidney Health Service, Royal Brisbane and Women’s Hospital, Herston, QLD 4029, Australia
| | - Belinda Mason
- Nutrition Research Collaborative, Department of Dietetics and Foodservices, Royal Brisbane and Women’s Hospital, Herston, QLD 4029, Australia (E.P.)
| |
Collapse
|
7
|
Souza ACR, Vasconcelos AR, Dias DD, Komoni G, Name JJ. The Integral Role of Magnesium in Muscle Integrity and Aging: A Comprehensive Review. Nutrients 2023; 15:5127. [PMID: 38140385 PMCID: PMC10745813 DOI: 10.3390/nu15245127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/09/2023] [Accepted: 12/14/2023] [Indexed: 12/24/2023] Open
Abstract
Aging is characterized by significant physiological changes, with the degree of decline varying significantly among individuals. The preservation of intrinsic capacity over the course of an individual's lifespan is fundamental for healthy aging. Locomotion, which entails the capacity for independent movement, is intricately connected with various dimensions of human life, including cognition, vitality, sensory perception, and psychological well-being. Notably, skeletal muscle functions as a pivotal nexus within this intricate framework. Any perturbation in its functionality can manifest as compromised physical performance and an elevated susceptibility to frailty. Magnesium is an essential mineral that plays a central role in approximately 800 biochemical reactions within the human body. Its distinctive physical and chemical attributes render it an indispensable stabilizing factor in the orchestration of diverse cellular reactions and organelle functions, thereby rendering it irreplaceable in processes directly impacting muscle health. This narrative review offers a comprehensive exploration of the pivotal role played by magnesium in maintaining skeletal muscle integrity, emphasizing the critical importance of maintaining optimal magnesium levels for promoting healthy aging.
Collapse
Affiliation(s)
| | | | | | | | - José João Name
- Kilyos Assessoria, Cursos e Palestras, São Paulo 01311-100, Brazil; (A.C.R.S.); (A.R.V.); (D.D.D.); (G.K.)
| |
Collapse
|
8
|
Öberg CM, Sternby J, Nilsson A, Storr M, Flieg R, Harenski K, Roos V, Källquist L, Hobro S. Experimental hemodialysis in diet-induced ketosis and the potential use of dialysis as an adjuvant cancer treatment. Sci Rep 2023; 13:19476. [PMID: 37945638 PMCID: PMC10636042 DOI: 10.1038/s41598-023-46715-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 11/03/2023] [Indexed: 11/12/2023] Open
Abstract
Numerous in vivo studies on the ketogenic diet, a diet that can induce metabolic conditions resembling those following extended starvation, demonstrate strong outcomes on cancer survival, particularly when combined with chemo-, radio- or immunological treatments. However, the therapeutic application of ketogenic diets requires strict dietary adherence from well-informed and motivated patients, and it has recently been proposed that hemodialysis might be utilized to boost ketosis and further destabilize the environment for cancer cells. Yet, plasma ketones may be lost in the dialysate-lowering blood ketone levels. Here we performed a single 180-min experimental hemodialysis (HD) session in six anesthetized Sprague-Dawley rats given ketogenic diet for five days. Median blood ketone levels pre-dialysis were 3.5 mmol/L (IQR 2.2 to 5.6) and 3.8 mmol/L (IQR 2.2 to 5.1) after 180 min HD, p = 0.54 (95% CI - 0.6 to 1.2). Plasma glucose levels were reduced by 36% (- 4.5 mmol/L), p < 0.05 (95% CI - 6.7 to - 2.5). Standard base excess was increased from - 3.5 mmol/L (IQR - 4 to - 2) to 0.5 mmol/L (IQR - 1 to 3), p < 0.01 (95% CI 2.0 to 5.0). A theoretical model was applied confirming that intra-dialytic glucose levels decrease, and ketone levels slightly increase since hepatic ketone production far exceeds dialytic removal. Our experimental data and in-silico modeling indicate that elevated blood ketone levels during ketosis are maintained during hemodialysis despite dialytic removal.
Collapse
Affiliation(s)
- Carl M Öberg
- Department of Clinical Sciences Lund, Skåne University Hospital, Njurmottagningen SUS Lund, Barngatan 2a, 221 85, Lund, Sweden.
| | - Jan Sternby
- Baxter International Inc., Magistratsvägen 10, 22643, Lund, Sweden
| | - Anders Nilsson
- Baxter International Inc., Magistratsvägen 10, 22643, Lund, Sweden
| | - Markus Storr
- Baxter International Inc., 72379, Hechingen, Germany
| | - Ralf Flieg
- Baxter International Inc., 72379, Hechingen, Germany
| | - Kai Harenski
- Baxter Deutschland GmbH., 85 716, Unterschleissheim, Germany
| | - Viktoria Roos
- Baxter International Inc., Magistratsvägen 10, 22643, Lund, Sweden.
| | - Linda Källquist
- Baxter International Inc., Magistratsvägen 10, 22643, Lund, Sweden
| | - Sture Hobro
- Baxter International Inc., Magistratsvägen 10, 22643, Lund, Sweden
| |
Collapse
|
9
|
Kettritz R, Loffing J. Potassium homeostasis - Physiology and pharmacology in a clinical context. Pharmacol Ther 2023; 249:108489. [PMID: 37454737 DOI: 10.1016/j.pharmthera.2023.108489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/03/2023] [Accepted: 07/06/2023] [Indexed: 07/18/2023]
Abstract
Membrane voltage controls the function of excitable cells and is mainly a consequence of the ratio between the extra- and intracellular potassium concentration. Potassium homeostasis is safeguarded by balancing the extra-/intracellular distribution and systemic elimination of potassium to the dietary potassium intake. These processes adjust the plasma potassium concentration between 3.5 and 4.5 mmol/L. Several genetic and acquired diseases but also pharmacological interventions cause dyskalemias that are associated with increased morbidity and mortality. The thresholds at which serum K+ not only associates but also causes increased mortality are hotly debated. We discuss physiologic, pathophysiologic, and pharmacologic aspects of potassium regulation and provide informative case vignettes. Our aim is to help clinicians, epidemiologists, and pharmacologists to understand the complexity of the potassium homeostasis in health and disease and to initiate appropriate treatment strategies in dyskalemic patients.
Collapse
Affiliation(s)
- Ralph Kettritz
- Department of Nephrology and Medical Intensive Care, Charité - Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany; Experimental and Clinical Research Center, Max Delbrück Center for Molecular Medicine in the Helmholtz Association and Charité Universitätsmedizin Berlin, Germany.
| | | |
Collapse
|
10
|
Al-Qusairi L, Ferdaus MZ, Pham TD, Li D, Grimm PR, Zapf AM, Abood DC, Tahaei E, Delpire E, Wall SM, Welling PA. Dietary anions control potassium excretion: it is more than a poorly absorbable anion effect. Am J Physiol Renal Physiol 2023; 325:F377-F393. [PMID: 37498547 PMCID: PMC10639028 DOI: 10.1152/ajprenal.00193.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 07/20/2023] [Accepted: 07/22/2023] [Indexed: 07/28/2023] Open
Abstract
The urinary potassium (K+) excretion machinery is upregulated with increasing dietary K+, but the role of accompanying dietary anions remains inadequately characterized. Poorly absorbable anions, including [Formula: see text], are thought to increase K+ secretion through a transepithelial voltage effect. Here, we tested if they also influence the K+ secretion machinery. Wild-type mice, aldosterone synthase (AS) knockout (KO) mice, or pendrin KO mice were randomized to control, high-KCl, or high-KHCO3 diets. The K+ secretory capacity was assessed in balance experiments. Protein abundance, modification, and localization of K+-secretory transporters were evaluated by Western blot analysis and confocal microscopy. Feeding the high-KHCO3 diet increased urinary K+ excretion and the transtubular K+ gradient significantly more than the high-KCl diet, coincident with more pronounced upregulation of epithelial Na+ channels (ENaC) and renal outer medullary K+ (ROMK) channels and apical localization in the distal nephron. Experiments in AS KO mice revealed that the enhanced effects of [Formula: see text] were aldosterone independent. The high-KHCO3 diet also uniquely increased the large-conductance Ca2+-activated K+ (BK) channel β4-subunit, stabilizing BKα on the apical membrane, the Cl-/[Formula: see text] exchanger, pendrin, and the apical KCl cotransporter (KCC3a), all of which are expressed specifically in pendrin-positive intercalated cells. Experiments in pendrin KO mice revealed that pendrin was required to increase K+ excretion with the high-KHCO3 diet. In summary, [Formula: see text] stimulates K+ excretion beyond a poorly absorbable anion effect, upregulating ENaC and ROMK in principal cells and BK, pendrin, and KCC3a in pendrin-positive intercalated cells. The adaptive mechanism prevents hyperkalemia and alkalosis with the consumption of alkaline ash-rich diets but may drive K+ wasting and hypokalemia in alkalosis.NEW & NOTEWORTHY Dietary anions profoundly impact K+ homeostasis. Here, we found that a K+-rich diet, containing [Formula: see text] as the counteranion, enhances the electrogenic K+ excretory machinery, epithelial Na+ channels, and renal outer medullary K+ channels, much more than a high-KCl diet. It also uniquely induces KCC3a and pendrin, in B-intercalated cells, providing an electroneutral KHCO3 secretion pathway. These findings reveal new K+ balance mechanisms that drive adaption to alkaline and K+-rich foods, which should guide new treatment strategies for K+ disorders.
Collapse
Affiliation(s)
- Lama Al-Qusairi
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Mohammed Z Ferdaus
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Truyen D Pham
- Department of Medicine Nephrology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Dimin Li
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - P Richard Grimm
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Ava M Zapf
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Delaney C Abood
- Department of Medicine Nephrology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Ebrahim Tahaei
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Susan M Wall
- Department of Medicine Nephrology, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Paul A Welling
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| |
Collapse
|
11
|
Abate V, Vergatti A, Fiore A, Forte A, Attanasio A, Altavilla N, De Filippo G, Rendina D, D Elia L. Low Potassium Intake: A Common Risk Factor for Nephrolithiasis in Patients with High Blood Pressure. High Blood Press Cardiovasc Prev 2023:10.1007/s40292-023-00587-0. [PMID: 37330455 PMCID: PMC10403441 DOI: 10.1007/s40292-023-00587-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 05/29/2023] [Indexed: 06/19/2023] Open
Abstract
Hypertension (Htn) is a crucial cause of cardio-vascular and chronic kidney disease. Moreover, it is an independent risk factor for nephrolithiasis (NL). A diet rich in vegetables and fruits is indicated for both Htn and NL prevention, and the 24-h urinary potassium excretion can be used as a warning light for adherence. The aim of this study is to demonstrate the association between urinary potassium excretion and recurrent nephrolithiasis among patients affected by Htn. We have analyzed medical records of 119 patients affected by Htn and NL (SF-Hs) referring to Bone and Mineral Metabolism laboratory and 119 patients affected by Htn but without NL (nSF-Hs) referring to Hypertension and Organ Damage Hypertension related laboratory, both in Federico II University of Naples. The potassium 24-h urinary levels in SF-Hs were significantly lower compared to nSF-Hs. This difference was confirmed by the multivariable linear regression analysis in the unadjusted model and adjusted model for age, gender, metabolic syndrome, and body mass index. In conclusion, a higher potassium urinary excretion in 24-h is a protective factor against NL in patients affected by Htn and dietary interventions can be considered for kidney protection.
Collapse
Affiliation(s)
- Veronica Abate
- Department of Clinical Medicine and Surgery, University Federico II, Naples, Via Sergio Pansini, 80131, Naples, Italy
| | - Anita Vergatti
- Department of Clinical Medicine and Surgery, University Federico II, Naples, Via Sergio Pansini, 80131, Naples, Italy
| | - Antonella Fiore
- Department of Clinical Medicine and Surgery, University Federico II, Naples, Via Sergio Pansini, 80131, Naples, Italy
| | - Angelo Forte
- Department of Clinical Medicine and Surgery, University Federico II, Naples, Via Sergio Pansini, 80131, Naples, Italy
| | - Alessia Attanasio
- Department of Clinical Medicine and Surgery, University Federico II, Naples, Via Sergio Pansini, 80131, Naples, Italy
| | - Nadia Altavilla
- Department of Clinical Medicine and Surgery, University Federico II, Naples, Via Sergio Pansini, 80131, Naples, Italy
| | - Gianpaolo De Filippo
- Assistance Publique-Hôpitaux de Paris, Hôpital Robert-Debré, Service d'Endocrinologie-Diabétologie, 75019, Paris, France
| | - Domenico Rendina
- Department of Clinical Medicine and Surgery, University Federico II, Naples, Via Sergio Pansini, 80131, Naples, Italy.
| | - Lanfranco D Elia
- Department of Clinical Medicine and Surgery, University Federico II, Naples, Via Sergio Pansini, 80131, Naples, Italy
| |
Collapse
|
12
|
Saha B, Shabbir W, Takagi E, Duan XP, Leite Dellova DCA, Demko J, Manis A, Loffing-Cueni D, Loffing J, Sørensen MV, Wang WH, Pearce D. Potassium Activates mTORC2-dependent SGK1 Phosphorylation to Stimulate Epithelial Sodium Channel: Role in Rapid Renal Responses to Dietary Potassium. J Am Soc Nephrol 2023; 34:1019-1038. [PMID: 36890646 PMCID: PMC10278851 DOI: 10.1681/asn.0000000000000109] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 02/06/2023] [Indexed: 03/10/2023] Open
Abstract
SIGNIFICANCE STATEMENT Rapid renal responses to ingested potassium are essential to prevent hyperkalemia and also play a central role in blood pressure regulation. Although local extracellular K + concentration in kidney tissue is increasingly recognized as an important regulator of K + secretion, the underlying mechanisms that are relevant in vivo remain controversial. To assess the role of the signaling kinase mTOR complex-2 (mTORC2), the authors compared the effects of K + administered by gavage in wild-type mice and knockout mice with kidney tubule-specific inactivation of mTORC2. They found that mTORC2 is rapidly activated to trigger K + secretion and maintain electrolyte homeostasis. Downstream targets of mTORC2 implicated in epithelial sodium channel regulation (SGK1 and Nedd4-2) were concomitantly phosphorylated in wild-type, but not knockout, mice. These findings offer insight into electrolyte physiologic and regulatory mechanisms. BACKGROUND Increasing evidence implicates the signaling kinase mTOR complex-2 (mTORC2) in rapid renal responses to changes in plasma potassium concentration [K + ]. However, the underlying cellular and molecular mechanisms that are relevant in vivo for these responses remain controversial. METHODS We used Cre-Lox-mediated knockout of rapamycin-insensitive companion of TOR (Rictor) to inactivate mTORC2 in kidney tubule cells of mice. In a series of time-course experiments in wild-type and knockout mice, we assessed urinary and blood parameters and renal expression and activity of signaling molecules and transport proteins after a K + load by gavage. RESULTS A K + load rapidly stimulated epithelial sodium channel (ENaC) processing, plasma membrane localization, and activity in wild-type, but not in knockout, mice. Downstream targets of mTORC2 implicated in ENaC regulation (SGK1 and Nedd4-2) were concomitantly phosphorylated in wild-type, but not knockout, mice. We observed differences in urine electrolytes within 60 minutes, and plasma [K + ] was greater in knockout mice within 3 hours of gavage. Renal outer medullary potassium (ROMK) channels were not acutely stimulated in wild-type or knockout mice, nor were phosphorylation of other mTORC2 substrates (PKC and Akt). CONCLUSIONS The mTORC2-SGK1-Nedd4-2-ENaC signaling axis is a key mediator of rapid tubule cell responses to increased plasma [K + ] in vivo . The effects of K + on this signaling module are specific, in that other downstream mTORC2 targets, such as PKC and Akt, are not acutely affected, and ROMK and Large-conductance K + (BK) channels are not activated. These findings provide new insight into the signaling network and ion transport systems that underlie renal responses to K +in vivo .
Collapse
Affiliation(s)
- Bidisha Saha
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | - Waheed Shabbir
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | - Enzo Takagi
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | - Xin-Peng Duan
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Deise Carla Almeida Leite Dellova
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
- Current address: Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga, Sao Paulo, Brazil
| | - John Demko
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | - Anna Manis
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| | | | | | - Mads Vaarby Sørensen
- Department of Biomedicine, Unit of Physiology, Aarhus University, Aarhus, Denmark
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - David Pearce
- Department of Medicine, Division of Nephrology, Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California
| |
Collapse
|
13
|
Little R, Murali SK, Poulsen SB, Grimm PR, Assmus A, Cheng L, Ivy JR, Hoorn EJ, Matchkov V, Welling PA, Fenton RA. Dissociation of sodium-chloride cotransporter expression and blood pressure during chronic high dietary potassium supplementation. JCI Insight 2023; 8:156437. [PMID: 36719746 PMCID: PMC10077486 DOI: 10.1172/jci.insight.156437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 01/25/2023] [Indexed: 02/01/2023] Open
Abstract
Dietary potassium (K+) supplementation is associated with a lowering effect in blood pressure (BP), but not all studies agree. Here, we examined the effects of short- and long-term K+ supplementation on BP in mice, whether differences depend on the accompanying anion or the sodium (Na+) intake and molecular alterations in the kidney that may underlie BP changes. Relative to the control diet, BP was higher in mice fed a high NaCl (1.57% Na+) diet for 7 weeks or fed a K+-free diet for 2 weeks. BP was highest on a K+-free/high NaCl diet. Commensurate with increased abundance and phosphorylation of the thiazide sensitive sodium-chloride-cotransporter (NCC) on the K+-free/high NaCl diet, BP returned to normal with thiazides. Three weeks of a high K+ diet (5% K+) increased BP (predominantly during the night) independently of dietary Na+ or anion intake. Conversely, 4 days of KCl feeding reduced BP. Both feeding periods resulted in lower NCC levels but in increased levels of cleaved (active) α and γ subunits of the epithelial Na+ channel ENaC. The elevated BP after chronic K+ feeding was reduced by amiloride but not thiazide. Our results suggest that dietary K+ has an optimal threshold where it may be most effective for cardiovascular health.
Collapse
Affiliation(s)
- Robert Little
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Søren B Poulsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Paul R Grimm
- Departments of Medicine, Nephrology and Physiology, Johns Hopkins School of Medicine, Baltimore, USA
| | - Adrienne Assmus
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Lei Cheng
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Jessica R Ivy
- University/BHF Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Ewout J Hoorn
- Department of Internal Medicine, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | | | - Paul A Welling
- Departments of Medicine, Nephrology and Physiology, Johns Hopkins School of Medicine, Baltimore, USA
| | - Robert A Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| |
Collapse
|
14
|
McCormick JA, Topf J, Tomacruz ID, Grimm PR. A New Understanding of Potassium's Influence Upon Human Health and Renal Physiology. ADVANCES IN KIDNEY DISEASE AND HEALTH 2023; 30:137-147. [PMID: 36868729 DOI: 10.1053/j.akdh.2023.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 12/28/2022] [Accepted: 01/03/2023] [Indexed: 03/05/2023]
Abstract
Potassium channels are expressed in virtually all cell types, and their activity is the dominant determinant of cellular membrane potential. As such, potassium flux is a key regulator of many cellular processes including the regulation of action potentials in excitable cells. Subtle changes in extracellular potassium can initiate signaling processes vital for survival (insulin signaling) while more extreme and chronic changes may lead to pathological states (acid-base disturbances and cardiac arrhythmia). While many factors acutely influence extracellular potassium levels, it is principally the role of the kidneys to maintain potassium balance by matching urinary excretion with dietary intake. When this balance is disrupted, human health is negatively impacted. In this review, we discuss evolving views of dietary potassium intake as means of preventing and mitigating diseases. We also provide an update on a molecular pathway called the potassium switch, a mechanism by which extracellular potassium regulates distal nephron sodium reabsorption. Finally, we review recent literature describing how several popular therapeutics influence potassium homeostasis.
Collapse
Affiliation(s)
- James A McCormick
- Division of Nephrology and Hypertension, Oregon Health and Science University, Portland, OR
| | - Joel Topf
- Department of Medicine, Oakland University William Beaumont School of Medicine, Rochester, MI
| | | | - P Richard Grimm
- Division of Nephrology, Johns Hopkins University School of Medicine, Baltimore, MD.
| |
Collapse
|
15
|
Maaliki D, Itani MM, Itani HA. Pathophysiology and genetics of salt-sensitive hypertension. Front Physiol 2022; 13:1001434. [PMID: 36176775 PMCID: PMC9513236 DOI: 10.3389/fphys.2022.1001434] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 08/29/2022] [Indexed: 11/13/2022] Open
Abstract
Most hypertensive cases are primary and heavily associated with modifiable risk factors like salt intake. Evidence suggests that even small reductions in salt consumption reduce blood pressure in all age groups. In that regard, the ACC/AHA described a distinct set of individuals who exhibit salt-sensitivity, regardless of their hypertensive status. Data has shown that salt-sensitivity is an independent risk factor for cardiovascular events and mortality. However, despite extensive research, the pathogenesis of salt-sensitive hypertension is still unclear and tremendously challenged by its multifactorial etiology, complicated genetic influences, and the unavailability of a diagnostic tool. So far, the important roles of the renin-angiotensin-aldosterone system, sympathetic nervous system, and immune system in the pathogenesis of salt-sensitive hypertension have been studied. In the first part of this review, we focus on how the systems mentioned above are aberrantly regulated in salt-sensitive hypertension. We follow this with an emphasis on genetic variants in those systems that are associated with and/or increase predisposition to salt-sensitivity in humans.
Collapse
Affiliation(s)
- Dina Maaliki
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Maha M. Itani
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Hana A. Itani
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, United States
- *Correspondence: Hana A. Itani,
| |
Collapse
|
16
|
The kidneys matter. Pflugers Arch 2022; 474:755-757. [PMID: 35895104 PMCID: PMC9338890 DOI: 10.1007/s00424-022-02737-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
17
|
Pearce D, Manis AD, Nesterov V, Korbmacher C. Regulation of distal tubule sodium transport: mechanisms and roles in homeostasis and pathophysiology. Pflugers Arch 2022; 474:869-884. [PMID: 35895103 PMCID: PMC9338908 DOI: 10.1007/s00424-022-02732-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/09/2022] [Accepted: 07/11/2022] [Indexed: 02/03/2023]
Abstract
Regulated Na+ transport in the distal nephron is of fundamental importance to fluid and electrolyte homeostasis. Further upstream, Na+ is the principal driver of secondary active transport of numerous organic and inorganic solutes. In the distal nephron, Na+ continues to play a central role in controlling the body levels and concentrations of a more select group of ions, including K+, Ca++, Mg++, Cl-, and HCO3-, as well as water. Also, of paramount importance are transport mechanisms aimed at controlling the total level of Na+ itself in the body, as well as its concentrations in intracellular and extracellular compartments. Over the last several decades, the transporters involved in moving Na+ in the distal nephron, and directly or indirectly coupling its movement to that of other ions have been identified, and their interrelationships brought into focus. Just as importantly, the signaling systems and their components-kinases, ubiquitin ligases, phosphatases, transcription factors, and others-have also been identified and many of their actions elucidated. This review will touch on selected aspects of ion transport regulation, and its impact on fluid and electrolyte homeostasis. A particular focus will be on emerging evidence for site-specific regulation of the epithelial sodium channel (ENaC) and its role in both Na+ and K+ homeostasis. In this context, the critical regulatory roles of aldosterone, the mineralocorticoid receptor (MR), and the kinases SGK1 and mTORC2 will be highlighted. This includes a discussion of the newly established concept that local K+ concentrations are involved in the reciprocal regulation of Na+-Cl- cotransporter (NCC) and ENaC activity to adjust renal K+ secretion to dietary intake.
Collapse
Affiliation(s)
- David Pearce
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA USA
| | - Anna D. Manis
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA USA
| | - Viatcheslav Nesterov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, Erlangen, Germany
| |
Collapse
|