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Duan XP, Zheng JY, Jiang SP, Wang MX, Zhang C, Chowdhury T, Wang WH, Lin DH. mTORc2 in Distal Convoluted Tubule and Renal K + Excretion during High Dietary K + Intake. J Am Soc Nephrol 2024; 35:00001751-990000000-00330. [PMID: 38788191 PMCID: PMC11387030 DOI: 10.1681/asn.0000000000000406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 05/20/2024] [Indexed: 05/26/2024] Open
Abstract
Key Points
High K stimulates mechanistic target of rapamycin complex 2 (mTORc2) in the distal convoluted tubule (DCT).Inhibition of mTORc2 decreased the basolateral Kir4.1/Kir5.1 and Na-Cl cotransporter in the DCT.Inhibition of mTORc2 of the DCT compromised kidneys' ability to excrete potassium during high K intake.
Background
Renal mechanistic target of rapamycin complex 2 (mTORc2) plays a role in regulating renal K+ excretion (renal-EK) and K+ homeostasis. Inhibition of renal mTORc2 causes hyperkalemia due to suppressing epithelial Na+ channel and renal outer medullary K+ (Kir1.1) in the collecting duct. We now explore whether mTORc2 of distal convoluted tubules (DCTs) regulates basolateral Kir4.1/Kir5.1, Na-Cl cotransporter (NCC), and renal-EK.
Methods
We used patch-clamp technique to examine basolateral Kir4.1/Kir5.1 in early DCT, immunoblotting, and immunofluorescence to examine NCC expression and in vivo measurement of urinary K+ excretion to determine baseline renal-EK in mice treated with an mTORc2 inhibitor and in DCT-specific rapamycin-insensitive companion of mTOR knockout (DCT-RICTOR-KO) mice.
Results
Inhibition of mTORc2 with AZD8055 abolished high-K+–induced inhibition of Kir4.1/Kir5.1 in DCT, high potassium–induced depolarization of the DCT membrane, and high potassium–induced suppression of phosphorylated Na-Cl cotransporter (pNCC) expression. AZD8055 stimulated the 40-pS inwardly rectifying K+ channel (Kir4.1/Kir5.1-heterotetramer) in early DCT in the mice on overnight high potassium intake; this effect was absent in the presence of protein kinase C inhibitors, which also stimulated Kir4.1/Kir5.1. AZD8055 treatment decreased renal-EK in animals on overnight high-potassium diet. Deletion of RICTOR in the DCT increased the Kir4.1/Kir5.1-mediated K+ currents, hyperpolarized the DCT membrane, and increased the expression of pWNK4 and pNCC. Renal-EK was lower and plasma K+ was higher in DCT-RICTOR-KO mice than corresponding control mice. In addition, overnight high-potassium diet did not inhibit Kir4.1/Kir5.1 activity in the DCT and failed to inhibit the expression of pNCC in DCT-RICTOR-KO mice. Overnight high potassium intake stimulated renal-EK in control mice, but this effect was attenuated in DCT-RICTOR-KO mice. Thus, overnight high potassium intake induced hyperkalemia in DCT-RICTOR-KO mice but not in control mice.
Conclusions
mTORc2 of the DCT inhibits Kir4.1/Kir5.1 activity and NCC expression and stimulates renal-EK during high potassium intake.
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Affiliation(s)
- Xin-Peng Duan
- Department of Physiology, Xuzhou Medical University, Xuzhou, China
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Jun-Ya Zheng
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Shao-Peng Jiang
- Department of Physiology, Zhuhai Campus of Zunyi Medical University, Zhuhai, China
| | - Ming-Xiao Wang
- Department of Physiology, Zhuhai Campus of Zunyi Medical University, Zhuhai, China
| | - Chengbiao Zhang
- Department of Physiology, Xuzhou Medical University, Xuzhou, China
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Tanzina Chowdhury
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, New York
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York
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2
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Bahena-Lopez JP, Vergara L, de la-Peña V, Gutierrez-Gallardo MA, López-Ibargüen P, García JA, Contreras-Carbajal H, Vázquez N, Rincón-Heredia R, Masso F, Bobadilla NA, Castañeda-Bueno M, Ellison DH, Gamba G, Chávez-Canales M. KS-WNK1 is required for the renal response to extreme changes in potassium intake. Am J Physiol Renal Physiol 2024; 326:F460-F476. [PMID: 38269409 PMCID: PMC11207588 DOI: 10.1152/ajprenal.00235.2023] [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: 08/09/2023] [Revised: 01/03/2024] [Accepted: 01/03/2024] [Indexed: 01/26/2024] Open
Abstract
Kidney-specific with-no-lysine kinase 1 (KS-WNK1) is an isoform of WNK1 kinase that is predominantly found in the distal convoluted tubule of the kidney. The precise physiological function of KS-WNK1 remains unclear. Some studies have suggested that it could play a role in regulating potassium renal excretion by modulating the activity of the Na+-Cl- cotransporter (NCC). However, changes in the potassium diet from normal to high failed to reveal a role for KS-WNK1, but under a normal-potassium diet, the expression of KS-WNK1 is negligible. It is only detectable when mice are exposed to a low-potassium diet. In this study, we investigated the role of KS-WNK1 in regulating potassium excretion under extreme changes in potassium intake. After following a zero-potassium diet (0KD) for 10 days, KS-WNK1-/- mice had lower plasma levels of K+ and Cl- while exhibiting higher urinary excretion of Na+, Cl-, and K+ compared with KS-WNK1+/+ mice. After 10 days of 0KD or normal-potassium diet (NKD), all mice were challenged with a high-potassium diet (HKD). Plasma K+ levels markedly increased after the HKD challenge only in mice previously fed with 0KD, regardless of genotype. KSWNK1+/+ mice adapt better to HKD challenge than KS-WNK1-/- mice after a potassium-retaining state. The difference in the phosphorylated NCC-to-NCC ratio between KS-WNK1+/+ and KS-WNK1-/- mice after 0KD and HKD indicates a role for KS-WNK1 in both NCC phosphorylation and dephosphorylation. These observations show that KS-WNK1 helps the distal convoluted tubule to respond to extreme changes in potassium intake, such as those occurring in wildlife.NEW & NOTEWORTHY The findings of this study demonstrate that kidney-specific with-no-lysine kinase 1 plays a role in regulating urinary electrolyte excretion during extreme changes in potassium intake, such as those occurring in wildlife. .
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Affiliation(s)
- Jessica Paola Bahena-Lopez
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
- MD/PhD program (Programa de Estudios Combinados en Medicina), Faculty of Medicine, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Laura Vergara
- Unidad de Investigación UNAM-INCICH, Instituto Nacional de Cardiología Ignacio Chávez and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Valeria de la-Peña
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
- Unidad de Investigación UNAM-INCICH, Instituto Nacional de Cardiología Ignacio Chávez and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Miguel A Gutierrez-Gallardo
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
- MD/PhD program (Programa de Estudios Combinados en Medicina), Faculty of Medicine, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Paulina López-Ibargüen
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Janeth Alejandra García
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Héctor Contreras-Carbajal
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Norma Vázquez
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Ruth Rincón-Heredia
- Unidad de Imagenología, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Felipe Masso
- Unidad de Investigación UNAM-INCICH, Instituto Nacional de Cardiología Ignacio Chávez and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Norma A Bobadilla
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - María Castañeda-Bueno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon, United States
- Oregon Clinical and Translational Research Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Gerardo Gamba
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
- MD/PhD program (Programa de Estudios Combinados en Medicina), Faculty of Medicine, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - María Chávez-Canales
- Unidad de Investigación UNAM-INCICH, Instituto Nacional de Cardiología Ignacio Chávez and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
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3
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Gamba G. Thirty years of the NaCl cotransporter: from cloning to physiology and structure. Am J Physiol Renal Physiol 2023; 325:F479-F490. [PMID: 37560773 PMCID: PMC10639029 DOI: 10.1152/ajprenal.00114.2023] [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: 05/02/2023] [Revised: 08/08/2023] [Accepted: 08/08/2023] [Indexed: 08/11/2023] Open
Abstract
The primary structure of the thiazide-sensitive NaCl cotransporter (NCC) was resolved 30 years ago by the molecular identification of the cDNA encoding this cotransporter, from the winter's flounder urinary bladder, following a functional expression strategy. This review outlines some aspects of how the knowledge about thiazide diuretics and NCC evolved, the history of the cloning process, and the expansion of the SLC12 family of electroneutral cotransporters. The diseases associated with activation or inactivation of NCC are discussed, as well as the molecular model by which the activity of NCC is regulated. The controversies in the field are discussed as well as recent publication of the three-dimensional model of NCC obtained by cryo-electron microscopy, revealing not only the amino acid residues critical for Na+ and Cl- translocation but also the residues critical for polythiazide binding to the transporter, opening the possibility for a new era in thiazide diuretic therapy.
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Affiliation(s)
- Gerardo Gamba
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
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4
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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: 3] [Impact Index Per Article: 3.0] [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.
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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.
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5
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Johnston JG, Welch AK, Cain BD, Sayeski PP, Gumz ML, Wingo CS. Aldosterone: Renal Action and Physiological Effects. Compr Physiol 2023; 13:4409-4491. [PMID: 36994769 DOI: 10.1002/cphy.c190043] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Aldosterone exerts profound effects on renal and cardiovascular physiology. In the kidney, aldosterone acts to preserve electrolyte and acid-base balance in response to changes in dietary sodium (Na+ ) or potassium (K+ ) intake. These physiological actions, principally through activation of mineralocorticoid receptors (MRs), have important effects particularly in patients with renal and cardiovascular disease as demonstrated by multiple clinical trials. Multiple factors, be they genetic, humoral, dietary, or otherwise, can play a role in influencing the rate of aldosterone synthesis and secretion from the adrenal cortex. Normally, aldosterone secretion and action respond to dietary Na+ intake. In the kidney, the distal nephron and collecting duct are the main targets of aldosterone and MR action, which stimulates Na+ absorption in part via the epithelial Na+ channel (ENaC), the principal channel responsible for the fine-tuning of Na+ balance. Our understanding of the regulatory factors that allow aldosterone, via multiple signaling pathways, to function properly clearly implicates this hormone as central to many pathophysiological effects that become dysfunctional in disease states. Numerous pathologies that affect blood pressure (BP), electrolyte balance, and overall cardiovascular health are due to abnormal secretion of aldosterone, mutations in MR, ENaC, or effectors and modulators of their action. Study of the mechanisms of these pathologies has allowed researchers and clinicians to create novel dietary and pharmacological targets to improve human health. This article covers the regulation of aldosterone synthesis and secretion, receptors, effector molecules, and signaling pathways that modulate its action in the kidney. We also consider the role of aldosterone in disease and the benefit of mineralocorticoid antagonists. © 2023 American Physiological Society. Compr Physiol 13:4409-4491, 2023.
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Affiliation(s)
- Jermaine G Johnston
- Division of Nephrology, Hypertension and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida, USA
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, USA
- Nephrology Section, Veteran Administration Medical Center, North Florida/South Georgia Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida, USA
| | - Amanda K Welch
- Division of Nephrology, Hypertension and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida, USA
- Nephrology Section, Veteran Administration Medical Center, North Florida/South Georgia Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida, USA
| | - Brian D Cain
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA
| | - Peter P Sayeski
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, USA
| | - Michelle L Gumz
- Division of Nephrology, Hypertension and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida, USA
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, USA
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA
- Nephrology Section, Veteran Administration Medical Center, North Florida/South Georgia Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida, USA
| | - Charles S Wingo
- Division of Nephrology, Hypertension and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida, USA
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, USA
- Nephrology Section, Veteran Administration Medical Center, North Florida/South Georgia Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida, USA
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6
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Wu A, Wolley MJ, Mayr HL, Cheng L, Cowley D, Li B, Campbell KL, Terker AS, Ellison DH, Welling PA, Fenton RA, Stowasser M. Randomized trial on the effect of oral potassium chloride supplementation on the thiazide-sensitive sodium chloride cotransporter in healthy adults. Kidney Int Rep 2023. [DOI: 10.1016/j.ekir.2023.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023] Open
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7
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Johnston JG, Wingo CS. Potassium Homeostasis and WNK Kinases in the Regulation of the Sodium-Chloride Cotransporter: Hyperaldosteronism and Its Metabolic Consequences. KIDNEY360 2022; 3:1823-1828. [PMID: 36514400 PMCID: PMC9717643 DOI: 10.34067/kid.0005752022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 10/12/2022] [Indexed: 12/05/2022]
Affiliation(s)
- Jermaine G. Johnston
- Department of Medicine, University of Florida, Gainesville, Florida
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida
- Veterans Administration Medical Center, North Florida/South Georgia Veterans Health Administration, Gainesville, Florida
| | - Charles S. Wingo
- Department of Medicine, University of Florida, Gainesville, Florida
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida
- Veterans Administration Medical Center, North Florida/South Georgia Veterans Health Administration, Gainesville, Florida
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Meng XX, Zhang H, Meng GL, Jiang SP, Duan XP, Wang WH, Wang MX. The effect of high-dietary K + (HK) on Kir4.1/Kir5.1 and ROMK in the distal convoluted tubule (DCT) is not affected by gender and Cl - content of the diet. Front Physiol 2022; 13:1039029. [PMID: 36439248 PMCID: PMC9682262 DOI: 10.3389/fphys.2022.1039029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 10/27/2022] [Indexed: 11/11/2022] Open
Abstract
Basolateral potassium channels in the distal convoluted tubule (DCT) are composed of inwardly-rectifying potassium channel 4.1 (Kir4.1) and Kir5.1. Kir4.1 interacts with Kir5.1 to form a 40 pS K+ channel which is the only type K+ channel expressed in the basolateral membrane of the DCT. Moreover, Kir4.1/Kir5.1 heterotetramer plays a key role in determining the expression and activity of thiazide-sensitive Na-Cl cotransport (NCC). In addition to Kir4.1/Kir5.1, Kir1.1 (ROMK) is expressed in the apical membrane of the late DCT (DCT2) and plays a key role in mediating epithelial Na+ channel (ENaC)-dependent K+ excretion. High dietary-K+-intake (HK) stimulates ROMK and inhibits Kir4.1/Kir5.1 in the DCT. Inhibition of Kir4.1/Kir5.1 is essential for HK-induced suppression of NCC whereas the stimulation of ROMK is important for increasing ENaC-dependent K+ excretion during HK. We have now used the patch-clamp-technique to examine whether gender and Cl- content of K+-diet affect HK-induced inhibition of basolateral Kir4.1/Kir5.1 and HK-induced stimulation of ROMK. Single-channel-recording shows that basolateral 40 pS K+ channel (Kir4.1/Kir5.1) activity of the DCT defined by NPo was 1.34 (1% KCl, normal K, NK), 0.95 (5% KCl) and 1.03 (5% K+-citrate) in male mice while it was 1.47, 1.02 and 1.05 in female mice. The whole-cell recording shows that Kir4.1/Kir5.1-mediated-K+ current of the early-DCT (DCT1) was 1,170 pA (NK), 725 pA (5% KCl) and 700 pA (5% K+-citrate) in male mice whereas it was 1,125 pA, 674 pA and 700 pA in female mice. Moreover, K+-currents (IK) reversal potential of DCT (an index of membrane potential) was -63 mV (NK), -49 mV (5% KCl) and -49 mV (5% K-citrate) in the male mice whereas it was -63 mV, -50 mV and -50 mV in female mice. Finally, TPNQ-sensitive whole-cell ROMK-currents in the DCT2 /initial-connecting tubule (CNT) were 910 pA (NK), 1,520 pA (5% KCl) and 1,540 pA (5% K+-citrate) in male mice whereas the ROMK-mediated K+ currents were 1,005 pA, 1,590 pA and 1,570 pA in female mice. We conclude that the effect of HK intake on Kir4.1/Kir5.1 of the DCT and ROMK of DCT2/CNT is similar between male and female mice. Also, Cl- content in HK diets has no effect on HK-induced inhibition of Kir4.1/Kir5.1 of the DCT and HK-induced stimulation of ROMK in DCT2/CNT.
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Affiliation(s)
- Xin-Xin Meng
- Department of Physiology, Zhuhai Campus of Zunyi Medical University, Zhuhai, China
| | - Hao Zhang
- Department of Physiology, Zhuhai Campus of Zunyi Medical University, Zhuhai, China
| | - Gui-Lin Meng
- Department of Physiology, Zhuhai Campus of Zunyi Medical University, Zhuhai, China
| | - Shao-Peng Jiang
- Department of Physiology, Zhuhai Campus of Zunyi Medical University, Zhuhai, China
| | - Xin-Peng Duan
- Department of Pharmacology, New York Medical College, Valhalla, NY, United States
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, NY, United States,*Correspondence: Ming-Xiao Wang, ; Wen-Hui Wang,
| | - Ming-Xiao Wang
- Department of Physiology, Zhuhai Campus of Zunyi Medical University, Zhuhai, China,*Correspondence: Ming-Xiao Wang, ; Wen-Hui Wang,
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9
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Wu A, Wolley MJ, Fenton RA, Stowasser M. Using human urinary extracellular vesicles to study physiological and pathophysiological states and regulation of the sodium chloride cotransporter. Front Endocrinol (Lausanne) 2022; 13:981317. [PMID: 36105401 PMCID: PMC9465297 DOI: 10.3389/fendo.2022.981317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/09/2022] [Indexed: 11/29/2022] Open
Abstract
The thiazide-sensitive sodium chloride cotransporter (NCC), expressed in the renal distal convoluted tubule, plays a major role in Na+, Cl- and K+ homeostasis and blood pressure as exemplified by the symptoms of patients with non-functional NCC and Gitelman syndrome. NCC activity is modulated by a variety of hormones, but is also influenced by the extracellular K+ concentration. The putative "renal-K+ switch" mechanism is a relatively cohesive model that links dietary K+ intake to NCC activity, and may offer new targets for blood pressure control. However, a remaining hurdle for full acceptance of this model is the lack of human data to confirm molecular findings from animal models. Extracellular vesicles (EVs) have attracted attention from the scientific community due to their potential roles in intercellular communication, disease pathogenesis, drug delivery and as possible reservoirs of biomarkers. Urinary EVs (uEVs) are an excellent sample source for the study of physiology and pathology of renal, urothelial and prostate tissues, but the diverse origins of uEVs and their dynamic molecular composition present both methodological and data interpretation challenges. This review provides a brief overview of the state-of-the-art, challenges and knowledge gaps in current uEV-based analyses, with a focus on the application of uEVs to study the "renal-K+ switch" and NCC regulation. We also provide recommendations regarding biospecimen handling, processing and reporting requirements to improve experimental reproducibility and interoperability towards the realisation of the potential of uEV-derived biomarkers in hypertension and clinical practice.
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Affiliation(s)
- Aihua Wu
- Endocrine Hypertension Research Centre, University of Queensland Diamantina Institute, Greenslopes and Princess Alexandra Hospitals, Brisbane, QLD, Australia
| | - Martin J. Wolley
- Endocrine Hypertension Research Centre, University of Queensland Diamantina Institute, Greenslopes and Princess Alexandra Hospitals, Brisbane, QLD, Australia
- Department of Nephrology, Royal Brisbane and Women’s Hospital, Brisbane, QLD, Australia
| | | | - Michael Stowasser
- Endocrine Hypertension Research Centre, University of Queensland Diamantina Institute, Greenslopes and Princess Alexandra Hospitals, Brisbane, QLD, Australia
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Wang WH, Lin DH. Inwardly rectifying K + channels 4.1 and 5.1 (Kir4.1/Kir5.1) in the renal distal nephron. Am J Physiol Cell Physiol 2022; 323:C277-C288. [PMID: 35759440 PMCID: PMC9291425 DOI: 10.1152/ajpcell.00096.2022] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The inwardly rectifying potassium channel (Kir) 4.1 (encoded by KCNJ10) interacts with Kir5.1 (encoded by KCNJ16) to form a major basolateral K+ channel in the renal distal convoluted tubule (DCT), connecting tubule (CNT), and the cortical collecting duct (CCD). Kir4.1/Kir5.1 heterotetramer plays an important role in regulating Na+ and K+ transport in the DCT, CNT, and CCD. A recent development in the field has firmly established the role of Kir4.1/Kir5.1 heterotetramer of the DCT in the regulation of thiazide-sensitive Na-Cl cotransporter (NCC). Changes in Kir4.1/Kir5.1 activity of the DCT are an essential step for the regulation of NCC expression/activity induced by dietary K+ and Na+ intakes and play a role in modulating NCC by type 2 angiotensin II receptor (AT2R), bradykinin type II receptor (BK2R), and β-adrenergic receptor. Since NCC activity determines the Na+ delivery rate to the aldosterone-sensitive distal nephron (ASDN), a distal nephron segment from late DCT to CCD, Kir4.1/Kir5.1 activity plays a critical role not only in the regulation of renal Na+ absorption but also in modulating renal K+ excretion and maintaining K+ homeostasis. Thus, Kir4.1/Kir5.1 activity serves as an important component of renal K+ sensing mechanism. The main focus of this review is to provide an overview regarding the role of Kir4.1 and Kir5.1 of the DCT and CCD in the regulation of renal K+ excretion and Na+ absorption.
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Affiliation(s)
- Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York
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11
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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.
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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
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12
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Nuñez-Gonzalez L, Carrera N, Garcia-Gonzalez MA. Molecular Basis, Diagnostic Challenges and Therapeutic Approaches of Bartter and Gitelman Syndromes: A Primer for Clinicians. Int J Mol Sci 2021; 22:11414. [PMID: 34768847 PMCID: PMC8584233 DOI: 10.3390/ijms222111414] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/13/2021] [Accepted: 10/14/2021] [Indexed: 12/18/2022] Open
Abstract
Gitelman and Bartter syndromes are rare inherited diseases that belong to the category of renal tubulopathies. The genes associated with these pathologies encode electrolyte transport proteins located in the nephron, particularly in the Distal Convoluted Tubule and Ascending Loop of Henle. Therefore, both syndromes are characterized by alterations in the secretion and reabsorption processes that occur in these regions. Patients suffer from deficiencies in the concentration of electrolytes in the blood and urine, which leads to different systemic consequences related to these salt-wasting processes. The main clinical features of both syndromes are hypokalemia, hypochloremia, metabolic alkalosis, hyperreninemia and hyperaldosteronism. Despite having a different molecular etiology, Gitelman and Bartter syndromes share a relevant number of clinical symptoms, and they have similar therapeutic approaches. The main basis of their treatment consists of electrolytes supplements accompanied by dietary changes. Specifically for Bartter syndrome, the use of non-steroidal anti-inflammatory drugs is also strongly supported. This review aims to address the latest diagnostic challenges and therapeutic approaches, as well as relevant recent research on the biology of the proteins involved in disease. Finally, we highlight several objectives to continue advancing in the characterization of both etiologies.
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Affiliation(s)
- Laura Nuñez-Gonzalez
- Grupo de Xenetica e Bioloxia do Desenvolvemento das Enfermidades Renais, Laboratorio de Nefroloxia (No. 11), Instituto de Investigacion Sanitaria de Santiago (IDIS), Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain;
- Grupo de Medicina Xenomica, Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain
| | - Noa Carrera
- Grupo de Xenetica e Bioloxia do Desenvolvemento das Enfermidades Renais, Laboratorio de Nefroloxia (No. 11), Instituto de Investigacion Sanitaria de Santiago (IDIS), Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain;
- Grupo de Medicina Xenomica, Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain
- RedInRen (Red en Investigación Renal) RETIC (Redes Temáticas de Investigación Cooperativa en Salud), ISCIII (Instituto de Salud Carlos III), 28029 Madrid, Spain
| | - Miguel A. Garcia-Gonzalez
- Grupo de Xenetica e Bioloxia do Desenvolvemento das Enfermidades Renais, Laboratorio de Nefroloxia (No. 11), Instituto de Investigacion Sanitaria de Santiago (IDIS), Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain;
- Grupo de Medicina Xenomica, Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain
- RedInRen (Red en Investigación Renal) RETIC (Redes Temáticas de Investigación Cooperativa en Salud), ISCIII (Instituto de Salud Carlos III), 28029 Madrid, Spain
- Fundación Pública Galega de Medicina Xenomica—SERGAS, Complexo Hospitalario de Santiago de Compotela (CHUS), 15706 Santiago de Compostela, Spain
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13
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Hyndman KA, Isaeva E, Palygin O, Mendoza LD, Rodan AR, Staruschenko A, Pollock JS. Role of collecting duct principal cell NOS1β in sodium and potassium homeostasis. Physiol Rep 2021; 9:e15080. [PMID: 34665521 PMCID: PMC8525323 DOI: 10.14814/phy2.15080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 09/15/2021] [Accepted: 09/27/2021] [Indexed: 12/15/2022] Open
Abstract
The nitric oxide (NO)-generating enzyme, NO synthase-1β (NOS1β), is essential for sodium (Na+ ) homeostasis and blood pressure control. We previously showed that collecting duct principal cell NOS1β is critical for inhibition of the epithelial sodium channel (ENaC) during high Na+ intake. Previous studies on freshly isolated cortical collecting ducts (CCD) demonstrated that exogenous NO promotes basolateral potassium (K+ ) conductance through basolateral channels, presumably Kir 4.1 (Kcnj10) and Kir 5.1 (Kcnj16). We, therefore, investigated the effects of NOS1β knockout on Kir 4.1/Kir 5.1 channel activity. Indeed, in CHO cells overexpressing NOS1β and Kir 4.1/Kir 5.1, the inhibition of NO signaling decreased channel activity. Male littermate control and principal cell NOS1β knockout mice (CDNOS1KO) on a 7-day, 4% NaCl diet (HSD) were used to detect changes in basolateral K+ conductance. We previously demonstrated that CDNOS1KO mice have high circulating aldosterone despite a high-salt diet and appropriately suppressed renin. We observed greater Kir 4.1 cortical abundance and significantly greater Kir 4.1/Kir 5.1 single-channel activity in the principal cells from CDNOS1KO mice. Moreover, blocking aldosterone action with in vivo spironolactone treatment resulted in lower Kir 4.1 abundance and greater plasma K+ in the CDNOS1KO mice compared to controls. Lowering K+ content in the HSD prevented the high aldosterone and greater plasma Na+ of CDNOS1KO mice and normalized Kir 4.1 abundance. We conclude that during chronic HSD, lack of NOS1β leads to increased plasma K+ , enhanced circulating aldosterone, and activation of ENaC and Kir 4.1/Kir 5.1 channels. Thus, principal cell NOS1β is required for the regulation of both Na+ and K+ by the kidney.
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Affiliation(s)
- Kelly A. Hyndman
- Department of MedicineDivision of NephrologySection of Cardio‐Renal Physiology and MedicineUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Elena Isaeva
- Department of Cellular Biology, Neurobiology and AnatomyMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Oleg Palygin
- Division of NephrologyDepartment of MedicineMedical University of South CarolinaCharlestonSouth CarolinaUSA
| | - Luciano D. Mendoza
- Department of MedicineDivision of NephrologySection of Cardio‐Renal Physiology and MedicineUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Aylin R. Rodan
- Molecular Medicine ProgramUniversity of UtahSalt Lake CityUtahUSA
- The Department of Internal MedicineDivision of Nephrology and HypertensionUniversity of UtahSalt Lake CityUtahUSA
- The Department of Human GeneticsUniversity of UtahSalt Lake CityUtahUSA
- The Medical ServiceVeterans Affairs Salt Lake City Health Care SystemSalt Lake CityUtahUSA
| | - Alexander Staruschenko
- Department of Molecular Pharmacology and PhysiologyUniversity of South FloridaTampaFloridaUSA
- The James A. Haley Veterans HospitalTampaFloridaUSA
| | - Jennifer S. Pollock
- Department of MedicineDivision of NephrologySection of Cardio‐Renal Physiology and MedicineUniversity of Alabama at BirminghamBirminghamAlabamaUSA
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14
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Shibata S, Uchida S. Hyperkalemia in patients undergoing hemodialysis: its pathophysiology and management. Ther Apher Dial 2021; 26:3-14. [PMID: 34378859 PMCID: PMC9291487 DOI: 10.1111/1744-9987.13721] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/01/2021] [Accepted: 08/09/2021] [Indexed: 11/28/2022]
Abstract
Potassium is a major intracellular cation in the body, regulating membrane potential of excitable cells, such as cardiomyocytes and skeletal muscle cells. Because the kidney plays a critical role in controlling potassium balance, the elevation in serum potassium levels is one of the most common complications in patients with maintenance hemodialysis (MHD). In addition to reduced renal potassium excretion, the alteration in body potassium distribution owing to comorbid conditions may also contribute to dyskalemia. Besides potassium elimination through hemodialysis in MHD patients, accumulating data indicate the potential importance of extra‐renal elimination involving the gastrointestinal system, which can be affected by the inhibitors of the renin‐angiotensin‐aldosterone system. In this article, the literature on potassium physiology in MHD patients is reviewed with an emphasis on the changes from individuals with normal kidney function. This article also summarizes the findings of recent studies on dietary control, dialysate prescription, and pharmacological therapy.
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Affiliation(s)
- Shigeru Shibata
- Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan
| | - Shunya Uchida
- Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan.,Department of Health Care, Teikyo Heisei University, Tokyo, Japan
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15
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Duan XP, Wu P, Zhang DD, Gao ZX, Xiao Y, Ray EC, Wang WH, Lin DH. Deletion of Kir5.1 abolishes the effect of high Na + intake on Kir4.1 and Na +-Cl - cotransporter. Am J Physiol Renal Physiol 2021; 320:F1045-F1058. [PMID: 33900854 DOI: 10.1152/ajprenal.00004.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
High sodium (HS) intake inhibited epithelial Na+ channel (ENaC) in the aldosterone-sensitive distal nephron and Na+-Cl- cotransporter (NCC) by suppressing basolateral Kir4.1/Kir5.1 in the distal convoluted tubule (DCT), thereby increasing renal Na+ excretion but not affecting K+ excretion. The aim of the present study was to explore whether deletion of Kir5.1 compromises the inhibitory effect of HS on NCC expression/activity and renal K+ excretion. Patch-clamp experiments demonstrated that HS failed to inhibit DCT basolateral K+ channels and did not depolarize K+ current reversal potential of the DCT in Kir5.1 knockout (KO) mice. Moreover, deletion of Kir5.1 not only increased the expression of Kir4.1, phospho-NCC, and total NCC but also abolished the inhibitory effect of HS on the expression of Kir4.1, phospho-NCC, and total NCC and thiazide-induced natriuresis. Also, low sodium-induced stimulation of NCC expression/activity and basolateral K+ channels in the DCT were absent in Kir5.1 KO mice. Deletion of Kir5.1 decreased ENaC currents in the late DCT, and HS further inhibited ENaC activity in Kir5.1 KO mice. Finally, measurement of the basal renal K+ excretion rate with the modified renal clearance method demonstrated that long-term HS inhibited the renal K+ excretion rate and steadily increased plasma K+ levels in Kir5.1 KO mice but not in wild-type mice. We conclude that Kir5.1 plays an important role in mediating the effect of HS intake on basolateral K+ channels in the DCT and NCC activity/expression. Kir5.1 is involved in maintaining renal ability of K+ excretion during HS intake. NEW & NOTEWORTHY Kir5.1 plays an important role in mediating the effect of high sodium intake on basolateral K+ channels in the distal convoluted tubule and Na+-Cl- cotransporter activity/expression.
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Affiliation(s)
- Xin-Peng Duan
- Department of Pharmacology, New York Medical College, Valhalla, New York.,Department of Histology and Embryology, Xuzhou Medical University, Xuzhou, People's Republic of China
| | - Peng Wu
- Department of Pharmacology, New York Medical College, Valhalla, New York.,Institute of Hypertension and Kidney Disease, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China
| | - Dan-Dan Zhang
- Department of Pharmacology, New York Medical College, Valhalla, New York.,Guangdong-Hong Kong Joint Laboratory on Immunological and Genetic Kidney Diseases, Guangdong Academy of Medical Sciences, Guangdong Provincial People's Hospital, Guangzhou, People's Republic of China
| | - Zhong-Xiuzi Gao
- Department of Pharmacology, New York Medical College, Valhalla, New York.,Institute of Hypertension and Kidney Disease, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China
| | - Yu Xiao
- Department of Pharmacology, New York Medical College, Valhalla, New York.,Department of Physiology, Qiqihar Medical University, Qiqihar, People's Republic of China
| | - Evan C Ray
- Renal-Electrolyte Division, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York
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16
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Downie ML, Lopez Garcia SC, Kleta R, Bockenhauer D. Inherited Tubulopathies of the Kidney: Insights from Genetics. Clin J Am Soc Nephrol 2021; 16:620-630. [PMID: 32238367 PMCID: PMC8092065 DOI: 10.2215/cjn.14481119] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The kidney tubules provide homeostasis by maintaining the external milieu that is critical for proper cellular function. Without homeostasis, there would be no heartbeat, no muscle movement, no thought, sensation, or emotion. The task is achieved by an orchestra of proteins, directly or indirectly involved in the tubular transport of water and solutes. Inherited tubulopathies are characterized by impaired function of one or more of these specific transport molecules. The clinical consequences can range from isolated alterations in the concentration of specific solutes in blood or urine to serious and life-threatening disorders of homeostasis. In this review, we focus on genetic aspects of the tubulopathies and how genetic investigations and kidney physiology have crossfertilized each other and facilitated the identification of these disorders and their molecular basis. In turn, clinical investigations of genetically defined patients have shaped our understanding of kidney physiology.
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Affiliation(s)
- Mallory L. Downie
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Sergio C. Lopez Garcia
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Robert Kleta
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Detlef Bockenhauer
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
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17
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Gagnon KB, Delpire E. Sodium Transporters in Human Health and Disease. Front Physiol 2021; 11:588664. [PMID: 33716756 PMCID: PMC7947867 DOI: 10.3389/fphys.2020.588664] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 10/06/2020] [Indexed: 12/12/2022] Open
Abstract
Sodium (Na+) electrochemical gradients established by Na+/K+ ATPase activity drives the transport of ions, minerals, and sugars in both excitable and non-excitable cells. Na+-dependent transporters can move these solutes in the same direction (cotransport) or in opposite directions (exchanger) across both the apical and basolateral plasma membranes of polarized epithelia. In addition to maintaining physiological homeostasis of these solutes, increases and decreases in sodium may also initiate, directly or indirectly, signaling cascades that regulate a variety of intracellular post-translational events. In this review, we will describe how the Na+/K+ ATPase maintains a Na+ gradient utilized by multiple sodium-dependent transport mechanisms to regulate glucose uptake, excitatory neurotransmitters, calcium signaling, acid-base balance, salt-wasting disorders, fluid volume, and magnesium transport. We will discuss how several Na+-dependent cotransporters and Na+-dependent exchangers have significant roles in human health and disease. Finally, we will discuss how each of these Na+-dependent transport mechanisms have either been shown or have the potential to use Na+ in a secondary role as a signaling molecule.
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Affiliation(s)
- Kenneth B. Gagnon
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, United States
| | - Eric Delpire
- Department of Anesthesiology, School of Medicine, Vanderbilt University, Nashville, TN, United States
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18
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Xu S, Li J, Yang L, Wang CJ, Liu T, Weinstein AM, Palmer LG, Wang T. Sex difference in kidney electrolyte transport III: Impact of low K intake on thiazide-sensitive cation excretion in male and female mice. Pflugers Arch 2021; 473:1749-1760. [PMID: 34455480 PMCID: PMC8528772 DOI: 10.1007/s00424-021-02611-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/15/2021] [Accepted: 08/01/2021] [Indexed: 12/14/2022]
Abstract
We compared the regulation of the NaCl cotransporter (NCC) in adaptation to a low-K (LK) diet in male and female mice. We measured hydrochlorothiazide (HCTZ)-induced changes in urine volume (UV), glomerular filtration rate (GFR), absolute (ENa, EK), and fractional (FENa, FEK) excretion in male and female mice on control-K (CK, 1% KCl) and LK (0.1% KCl) diets for 7 days. With CK, NCC-dependent ENa and FENa were larger in females than males as observed previously. However, with LK, HCTZ-induced ENa and FENa increased in males but not in females, abolishing the sex differences in NCC function as observed in CK group. Despite large diuretic and natriuretic responses to HCTZ, EK was only slightly increased in response to the drug when animals were on LK. This suggests that the K-secretory apparatus in the distal nephron is strongly suppressed under these conditions. We also examined LK-induced changes in Na transport protein expression by Western blotting. Under CK conditions females expressed more NCC protein, as previously reported. LK doubled both total (tNCC) and phosphorylated NCC (pNCC) abundance in males but had more modest effects in females. The larger effect in males abolished the sex-dependence of NCC expression, consistent with the measurements of function by renal clearance. LK intake did not change NHE3, NHE2, or NKCC2 expression, but reduced the amount of the cleaved (presumably active) form of γENaC. LK reduced plasma K to lower levels in females than males. These results indicated that males had a stronger NCC-mediated adaptation to LK intake than females.
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Affiliation(s)
- Shuhua Xu
- grid.47100.320000000419368710Department of Cellular and Molecular Physiology, Yale School of Medicine University, 333 Cedar Street, P.O. Box 208026, New Haven, CT 06520-8026 USA
| | - Jing Li
- grid.47100.320000000419368710Department of Cellular and Molecular Physiology, Yale School of Medicine University, 333 Cedar Street, P.O. Box 208026, New Haven, CT 06520-8026 USA
| | - Lei Yang
- grid.5386.8000000041936877XDepartment of Physiology and Biophysics, Weill Medical College of Cornell University, New York, NY USA
| | - Claire J. Wang
- grid.47100.320000000419368710Department of Cellular and Molecular Physiology, Yale School of Medicine University, 333 Cedar Street, P.O. Box 208026, New Haven, CT 06520-8026 USA
| | - Tommy Liu
- grid.47100.320000000419368710Department of Cellular and Molecular Physiology, Yale School of Medicine University, 333 Cedar Street, P.O. Box 208026, New Haven, CT 06520-8026 USA
| | - Alan M. Weinstein
- grid.5386.8000000041936877XDepartment of Physiology and Biophysics, Weill Medical College of Cornell University, New York, NY USA
| | - Lawrence G. Palmer
- grid.5386.8000000041936877XDepartment of Physiology and Biophysics, Weill Medical College of Cornell University, New York, NY USA
| | - Tong Wang
- grid.47100.320000000419368710Department of Cellular and Molecular Physiology, Yale School of Medicine University, 333 Cedar Street, P.O. Box 208026, New Haven, CT 06520-8026 USA
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19
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Esposito P, Conti NE, Falqui V, Cipriani L, Picciotto D, Costigliolo F, Garibotto G, Saio M, Viazzi F. New Treatment Options for Hyperkalemia in Patients with Chronic Kidney Disease. J Clin Med 2020; 9:E2337. [PMID: 32707890 PMCID: PMC7465118 DOI: 10.3390/jcm9082337] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/09/2020] [Accepted: 07/21/2020] [Indexed: 02/07/2023] Open
Abstract
Hyperkalemia may cause life-threatening cardiac and neuromuscular alterations, and it is associated with high mortality rates. Its treatment includes a multifaceted approach, guided by potassium levels and clinical presentation. In general, treatment of hyperkalemia may be directed towards stabilizing cell membrane potential, promoting transcellular potassium shift and lowering total K+ body content. The latter can be obtained by dialysis, or by increasing potassium elimination by urine or the gastrointestinal tract. Until recently, the only therapeutic option for increasing fecal K+ excretion was represented by the cation-exchanging resin sodium polystyrene sulfonate. However, despite its common use, the efficacy of this drug has been poorly studied in controlled studies, and concerns about its safety have been reported. Interestingly, new drugs, namely patiromer and sodium zirconium cyclosilicate, have been developed to treat hyperkalemia by increasing gastrointestinal potassium elimination. These medications have proved their efficacy and safety in large clinical trials, involving subjects at high risk of hyperkalemia, such as patients with heart failure and chronic kidney disease. In this review, we discuss the mechanisms of action and the updated data of patiromer and sodium zirconium cyclosilicate, considering that the availability of these new treatment options offers the possibility of improving the management of both acute and chronic hyperkalemia.
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Affiliation(s)
- Pasquale Esposito
- Clinica Nefrologica, Dialisi, Trapianto, Department of Internal Medicine, University of Genoa and IRCCS Ospedale Policlinico San Martino, Viale Benedetto XV, 16132 Genoa, Italy; (N.E.C.); (V.F.); (L.C.); (D.P.); (F.C.); (G.G.); (M.S.); (F.V.)
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20
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Abstract
Eating more potassium may reduce blood pressure and the occurrence of other cardiovascular diseases by actions on various systems, including the vasculature, the sympathetic nervous system, systemic metabolism, and body fluid volume. Among these, the kidney plays a major role in the potassium-rich diet-mediated blood pressure reduction. PURPOSE OF REVIEW: To provide an overview of recent discoveries about the mechanisms by which a potassium-rich diet leads to natriuresis. RECENT FINDINGS: Although the distal convoluted tubule (DCT) is a short part of the nephron that reabsorbs salt, via the sodium-chloride cotransporter (NCC), it is highly sensitive to changes in plasma potassium concentration. Activation or inhibition of NCC raises or lowers blood pressure. Recent work suggests that extracellular potassium concentration is sensed by the DCT via intracellular chloride concentration which regulates WNK kinases in the DCT. High-potassium diet targets NCC in the DCT, resulting in natriuresis and fluid volume reduction, which are protective from hypertension and other cardiovascular problems.
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Affiliation(s)
- Xiao-Tong Su
- School of Medicine, Oregon Health and Science University, Portland, OR USA
| | - Chao-Ling Yang
- School of Medicine, Oregon Health and Science University, Portland, OR USA
| | - David H. Ellison
- School of Medicine, Oregon Health and Science University, Portland, OR USA ,Oregon Clinical & Translational Research Institute, SN4N, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239 USA ,Veterans Administration Portland Health Care System, Portland, OR USA
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21
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Hoorn EJ, Gritter M, Cuevas CA, Fenton RA. Regulation of the Renal NaCl Cotransporter and Its Role in Potassium Homeostasis. Physiol Rev 2020; 100:321-356. [DOI: 10.1152/physrev.00044.2018] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Daily dietary potassium (K+) intake may be as large as the extracellular K+ pool. To avoid acute hyperkalemia, rapid removal of K+ from the extracellular space is essential. This is achieved by translocating K+ into cells and increasing urinary K+ excretion. Emerging data now indicate that the renal thiazide-sensitive NaCl cotransporter (NCC) is critically involved in this homeostatic kaliuretic response. This suggests that the early distal convoluted tubule (DCT) is a K+ sensor that can modify sodium (Na+) delivery to downstream segments to promote or limit K+ secretion. K+ sensing is mediated by the basolateral K+ channels Kir4.1/5.1, a capacity that the DCT likely shares with other nephron segments. Thus, next to K+-induced aldosterone secretion, K+ sensing by renal epithelial cells represents a second feedback mechanism to control K+ balance. NCC’s role in K+ homeostasis has both physiological and pathophysiological implications. During hypovolemia, NCC activation by the renin-angiotensin system stimulates Na+ reabsorption while preventing K+ secretion. Conversely, NCC inactivation by high dietary K+ intake maximizes kaliuresis and limits Na+ retention, despite high aldosterone levels. NCC activation by a low-K+ diet contributes to salt-sensitive hypertension. K+-induced natriuresis through NCC offers a novel explanation for the antihypertensive effects of a high-K+ diet. A possible role for K+ in chronic kidney disease is also emerging, as epidemiological data reveal associations between higher urinary K+ excretion and improved renal outcomes. This comprehensive review will embed these novel insights on NCC regulation into existing concepts of K+ homeostasis in health and disease.
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Affiliation(s)
- Ewout J. Hoorn
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands; and Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Martin Gritter
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands; and Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Catherina A. Cuevas
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands; and Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Robert A. Fenton
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands; and Department of Biomedicine, Aarhus University, Aarhus, Denmark
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Diaz-Canestro C, Haider T, Lundby C, Montero D. Relationship between plasma volume and essential blood constituents in patients with heart failure and preserved ejection fraction. Clin Physiol Funct Imaging 2019; 40:131-138. [PMID: 31823430 DOI: 10.1111/cpf.12614] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Accepted: 12/04/2019] [Indexed: 12/25/2022]
Abstract
INTRODUCTION Notwithstanding recent progress on molecular mechanisms underlying heart failure with preserved ejection fraction (HFpEF), multiple pathophysiological aspects of this condition including the basis of anaemia and other haematological disorders remain unresolved. In this study, we sought to determine the relationship of plasma volume (PV), a plausible confounding factor for the concentration of solutes in blood, with key haematological markers in HFpEF patients. METHODS Total circulating PV was determined with high precision, automated carbon monoxide rebreathing in 24 stable HFpEF patients (70 ± 8 years, left ventricular ejection fraction = 55±5%) and 18 healthy age- and sex-matched control (HC) individuals. Linear regression analyses were performed to determine the association of PV with a comprehensive set of haematological variables. RESULTS Haematocrit (40·1 ± 4·9 versus 43·6 ± 2·7%, P = 0·004) and haemoglobin concentration (131 ± 16 versus 142 ± 7 g l-1 , P = 0·003) were reduced in HFpEF patients compared with HC individuals. In regression analyses, PV was negatively associated with haematocrit (r = -0·45, P = 0·029) and haemoglobin concentration (r = -0·44, P = 0·030) in HFpEF patients, whereas these variables were not associated with PV in HC individuals (P≥0·198). Regarding blood electrolytes, PV was negatively associated with K+ (r = -0·43, P = 0·036) and Ca2+ (r = -0·44, P = 0·032) in HFpEF patients but not in HC individuals (P≥0·734). None of the above associations were detected in HFpEF patients when using ideal instead of measured PV. CONCLUSION The blood concentration of routine markers of anaemia and electrolyte balance is specifically and linearly associated with PV in HFpEF patients. Excess or deficit of circulating PV may confound clinical diagnosis in this population.
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Affiliation(s)
- Candela Diaz-Canestro
- Faculty of Kinesiology, Cumming School of Medicine, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | - Thomas Haider
- University Heart Center, University Hospital Zurich, Zurich, Switzerland
| | - Carsten Lundby
- Inland Norway University of Applied Sciences, Lillehammer, Norway
| | - David Montero
- Faculty of Kinesiology, Cumming School of Medicine, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
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Mutig K, Bachmann S. Hyperkalemia and blood pressure regulation. Nephrol Dial Transplant 2019; 34:iii26-iii35. [PMID: 31800077 DOI: 10.1093/ndt/gfz218] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Indexed: 11/12/2022] Open
Abstract
Hypertension is common in the general population. Management of hypertensive patients at risk of hyperkalemia is challenging due to potential life-threatening complications such as cardiac arrest. Chronic hyperkalemia is often associated with impaired renal ability to excrete excessive potassium ions (K+). This may refer to chronic kidney disease or certain pharmacological interventions, including broadly used renin-angiotensin-aldosterone system and calcineurin inhibitors. Understanding the intrinsic mechanisms permitting kidney adaptations to hyperkalemia is critical for choosing therapeutic strategies. Valuable insights were obtained from the analysis of familial hyperkalemic hypertension (FHHt) syndrome, which became a classic model for coincidence of high blood pressure and hyperkalemia. FHHt can be caused by mutations in several genes, all of them resulting in excessive activity of with-no-lysine kinases (WNKs) in the distal nephron of the kidney. WNKs have been increasingly recognized as key signalling enzymes in the regulation of renal sodium ions (Na+) and K+ handling, enabling adaptive responses to systemic shifts of potassium homoeostasis consequent to variations in dietary potassium intake or disease. The WNK signalling pathway recruits a complex protein network mediating catalytic and non-catalytic effects of distinct WNK isoforms on relevant Na+- or K+-transporting proteins. In this review article, we summarize recent progress in understanding WNK signalling. An update of available models for renal adaptation to hyperkalemic conditions is presented. Consequences for blood pressure regulation are discussed. Pharmacological targeting of WNKs or their substrates offers promising options to manage hypertension while preventing hyperkalemia.
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Affiliation(s)
- Kerim Mutig
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Department of Pharmacology, I.M. Sechenov First Moscow State Medical University of the Ministry of Healthcare of the Russian Federation (Sechenovskiy University), Moscow, Russia
| | - Sebastian Bachmann
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
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Caravaca-Fontán F, Valladares J, Díaz-Campillejo R, Barroso S, Luna E, Caravaca F. Renal potassium handling in chronic kidney disease: Differences between patients with or wihtout hyperkalemia. Nefrologia 2019; 40:152-159. [PMID: 31353054 DOI: 10.1016/j.nefro.2019.04.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 03/09/2019] [Accepted: 04/11/2019] [Indexed: 01/14/2023] Open
Abstract
INTRODUCTION Hyperkalemia (HK) is a common electrolyte disorder in chronic kidney disease (CKD), mainly in the advanced stages. A positive potassium balance due to reduced renal excretory capacity is likely the main pathogenic mechanism of HK. Research into the relative role of each pathogenic element in the development of HK in CKD may help to implement more suitable therapies. OBJECTIVE To investigate renal potassium handling in advanced CKD patients, and to determine the differences between patients with or without HK. MATERIAL AND METHODS Cross-sectional observational study in adult patients with stage 4-5 CKD pre-dialysis. Selection criteria included clinically stable patients and the ability to collect a 24hour urine sample correctly. Blood and urinary biochemical parameters were analysed including sodium and potassium (K). Fractional excretion of K (FEK) and K load relative to glomerular filtration (Ku/GFR) were calculated. HK was defined as a serum K concentration ≥5.5mmol/l. RESULTS The study group consisted of 212 patients (mean age 65±14 years, 92 females) with a mean GFR of 15.0±4.2ml/min/1.73m2. 63 patients (30%) had HK. Patients with HK had lower mean bicarbonate levels with respect to patients with normal K levels (NK) (20.3±3.1 vs. 22.8±3.2 mEq/l, P<.0001), but no differences were noted in total urinary sodium and K excretion. While mean FEK values were lower in patients with HK (32.1±12.1% vs. 36.4±14.3%, P=.038), Ku/GFR values were significantly greater with respect to the NK subgroup (4.2±1.5 vs. 3.7±1.4 mmol/ml/min, P=0,049). FEK showed a strong linear correlation with Ku/GFR (R2=0.74), and partial linear regressions demonstrated that at a similar Ku/GFR level, the FEK of patients with HK was lower than that of NK patients. By multivariate linear and logistic regression analyses, both FEK and Ku/GFR were shown to be the main determinants of K serum levels and HK. CONCLUSIONS Although the K load relative to glomerular filtration (Ku/GFR) is an important determinant of HK in advanced CKD, the most noteworthy characteristic associated with HK in these patients was the limitation of compensatory urinary K excretion, as indicated by lower FEK.
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Affiliation(s)
| | | | | | - Sergio Barroso
- Servicio Nefrología, Hospital Infanta Cristina, Badajoz, España
| | - Enrique Luna
- Servicio Nefrología, Hospital Infanta Cristina, Badajoz, España
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25
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Mistry HD, Kurlak LO, Gardner DS, Torffvit O, Hansen A, Broughton Pipkin F, Strevens H. Evidence of Augmented Intrarenal Angiotensinogen Associated With Glomerular Swelling in Gestational Hypertension and Preeclampsia: Clinical Implications. J Am Heart Assoc 2019; 8:e012611. [PMID: 31237175 PMCID: PMC6662362 DOI: 10.1161/jaha.119.012611] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 05/17/2019] [Indexed: 12/19/2022]
Abstract
Background AGT (angiotensinogen) synthesis occurs in renal proximal tubular epithelial cells, independent from systemic AGT , as a component of the intrarenal renin-angiotensin system. We investigated urinary AGT , as a biomarker for renin-angiotensin system activation, and electrolyte concentrations, in relation to glomerular volume, as a proxy for glomerular endotheliosis in renal biopsy tissue from pregnant normotensive control and hypertensive women. Methods and Results Urine samples were collected from normotensive control (n=10), gestational hypertensive (n=6), and pre-eclamptic (n=16) women at the time a renal biopsy was obtained. Samples were collected from Lund University Hospital between November 1999 and June 2001. Urinary AGT , potassium, and sodium were measured, normalized to urinary creatinine. Mean glomerular volume was estimated from biopsy sections. AGT protein expression and localization were assessed in renal biopsies by immunohistochemistry. Urinary AGT concentrations were higher in hypertensive pregnancies (median, gestational hypertension: 11.3 ng/mmol [interquartile range: 2.8-13.6]; preeclampsia: 8.4 ng/mmol [interquartile range: 4.2-29.1]; normotensive control: 0.6 ng/mmol [interquartile range: 0.4-0.8]; P<0.0001) and showed a positive relationship with estimated mean glomerular volume. Urinary potassium strongly correlated with urinary AGT ( P<0.0001). Although numbers were small, AGT protein was found in both glomeruli and proximal tubules in normotensive control but was present only in proximal tubules in women with hypertensive pregnancy. Conclusions This study shows that pregnant women with gestational hypertension or preeclampsia have increased urinary AGT and potassium excretion associated with signs of glomerular swelling. Our data suggest that the kidneys of women with hypertensive pregnancies and endotheliosis have inappropriate intrarenal renin-angiotensin system activation, which may contribute toward the pathogenesis of hypertension and renal injury.
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Affiliation(s)
- Hiten D. Mistry
- Division of Child Health, Obstetrics & GynaecologySchool of MedicineUniversity of NottinghamUnited Kingdom
| | - Lesia O. Kurlak
- Division of Child Health, Obstetrics & GynaecologySchool of MedicineUniversity of NottinghamUnited Kingdom
| | - David S. Gardner
- School of Veterinary Medicine and ScienceUniversity of NottinghamUnited Kingdom
| | | | - Alastair Hansen
- Department of PathologyHerlev University HospitalHerlevDenmark
| | - Fiona Broughton Pipkin
- Division of Child Health, Obstetrics & GynaecologySchool of MedicineUniversity of NottinghamUnited Kingdom
| | - Helena Strevens
- Department of ObstetricsSkåne University HospitalLund UniversityLundSweden
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26
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Teulon J, Wang WH. Studying Na + and K + channels in aldosterone-sensitive distal nephrons. Methods Cell Biol 2019; 153:151-168. [PMID: 31395377 DOI: 10.1016/bs.mcb.2019.04.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Aldosterone-sensitive distal nephron (ASDN) including the distal convoluted tubule (DCT), connecting tubule (CNT) and collecting duct (CD) plays an important role in the regulation of hormone-dependent Na+ reabsorption and dietary K+-intake dependent K+ excretion. The major Na+ transporters in the ASDN are thiazide-sensitive Na-Cl cotransporter (NCC), epithelial Na+ channel (ENaC), pendrin/Na+-dependent Cl--bicarbonate exchanger (NDCBE). Whereas major K+ channels in the ASDN are Kir4.1 and Kir5.1 in the basolateral membrane; and Kir1.1 (ROMK) and Ca2+ activated big conductance K+ channel (BK) in the apical membrane. Although a variety of in vitro cell lines of the ASDN is available and these cell models have been employed for studying Na+ and K+ channels, the biophysical properties and the regulation of Na+ and K+ channels in vitro cell models may not be able to recapitulate those in vivo conditions. Thus, the studies performed in the native ASDN are essential for providing highly physiological relevant information and for understanding the Na+ and K+ transport in the ASDN. Here we provide a detailed methodology describing how to perform the electrophysiological measurement in the native DCT, CNT and cortical collecting duct (CCD).
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Affiliation(s)
- Jacques Teulon
- Sorbnne Université, Centre de recherches des Cordeliers UMR_S 1138, equipe 3, Paris, France.
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, NY, United States.
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27
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Sørensen MV, Saha B, Jensen IS, Wu P, Ayasse N, Gleason CE, Svendsen SL, Wang WH, Pearce D. Potassium acts through mTOR to regulate its own secretion. JCI Insight 2019; 5:126910. [PMID: 31013253 DOI: 10.1172/jci.insight.126910] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Potassium (K+) secretion by kidney tubule cells is central to electrolyte homeostasis in mammals. In the K+ secretory "principal" cells of the distal nephron, electrogenic Na+ transport by the epithelial sodium channel (ENaC) generates the electrical driving force for K+ transport across the apical membrane. Regulation of this process is attributable in part to aldosterone, which stimulates the gene transcription of the ENaC-regulatory kinase, SGK1. However, a wide range of evidence supports the conclusion that an unidentified aldosterone-independent pathway exists. We show here that in principal cells, K+ itself acts through the type 2 mTOR complex (mTORC2) to activate SGK1, which stimulates ENaC to enhance K+ excretion. The effect depends on changes in K+ concentration on the blood side of the cells, and requires basolateral membrane K+-channel activity. However, it does not depend on changes in aldosterone, or on enhanced distal delivery of Na+ from upstream nephron segments. These data strongly support the idea that K+ is sensed directly by principal cells to stimulate its own secretion by activating the mTORC2-SGK1 signaling module, and stimulate ENaC. We propose that this local effect acts in concert with aldosterone and increased Na+ delivery from upstream nephron segments to sustain K+ homeostasis.
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Affiliation(s)
- Mads Vaarby Sørensen
- Departments of Biomedicine and Physiology, Aarhus University, Aarhus, Denmark.,Aarhus Institute for Advanced Studies, Aarhus University, Aarhus, Denmark
| | - Bidisha Saha
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, UCSF, San Francisco, California, USA
| | - Iben Skov Jensen
- Departments of Biomedicine and Physiology, Aarhus University, Aarhus, Denmark
| | - Peng Wu
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA
| | - Niklas Ayasse
- Departments of Biomedicine and Physiology, Aarhus University, Aarhus, Denmark
| | - Catherine E Gleason
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, UCSF, San Francisco, California, USA
| | | | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA
| | - David Pearce
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, UCSF, San Francisco, California, USA
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28
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Abstract
PURPOSE OF REVIEW Renal ion transport undergoes dramatic changes during the course of gestation. These adaptations are necessary to meet the dynamic requirements of pregnancy and support fetal development. Pregnancy is characterized by a high demand for both sodium and potassium. Recently there has been work in the field profiling the modifications of the renal tubules in pregnancy to meet these demands. The purpose of this review is to summarize these findings. RECENT FINDINGS The work to date suggests an important role for the distal nephron in both the renal sodium and potassium reabsorption during pregnancy. There is strong evidence that renal sodium reabsorption is mediated by the epithelial sodium channel (ENaC). Whereas renal potassium reabsorption is mediated by upregulation of potassium retaining transporters (HKA2) and downregulation of potassium secreting channels (ROMK, BK). SUMMARY Fetal growth restriction and hypertensive disorders of pregnancy including preeclampsia are marked by suboptimal maternal plasma volume expansion, which is determined by renal electrolyte handling. Therefore, understanding the physiologic demand for sodium and potassium in pregnancy and the adaptations required to support these needs is necessary for the effective treatment of diseased states of pregnancy.
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29
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Su XT, Ellison DH, Wang WH. Kir4.1/Kir5.1 in the DCT plays a role in the regulation of renal K + excretion. Am J Physiol Renal Physiol 2019; 316:F582-F586. [PMID: 30623727 PMCID: PMC6459306 DOI: 10.1152/ajprenal.00412.2018] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 12/31/2018] [Accepted: 01/02/2019] [Indexed: 02/03/2023] Open
Abstract
The aim of this mini review is to provide an overview regarding the role of inwardly rectifying potassium channel 4.1 (Kir4.1)/Kir5.1 in regulating renal K+ excretion. Deletion of Kir4.1 in the kidney inhibited thiazide-sensitive NaCl cotransporter (NCC) activity in the distal convoluted tubule (DCT) and slightly suppressed Na-K-2Cl cotransporter (NKCC2) function in the thick ascending limb (TAL). Moreover, increased dietary K+ intake inhibited, whereas decreased dietary K+ intake stimulated, the basolateral potassium channel (a Kir4.1/Kir5.1 heterotetramer) in the DCT. The alteration of basolateral potassium conductance is essential for the effect of dietary K+ intake on NCC because deletion of Kir4.1 in the DCT abolished the effect of dietary K+ intake on NCC. Since potassium intake-mediated regulation of NCC plays a key role in regulating renal K+ excretion and potassium homeostasis, the deletion of Kir4.1 caused severe hypokalemia and metabolic alkalosis under control conditions and even during increased dietary K+ intake. Finally, recent studies have suggested that the angiotensin II type 2 receptor (AT2R) and bradykinin-B2 receptor (BK2R) are involved in mediating the effect of high dietary K+ intake on Kir4.1/Kir5.1 in the DCT.
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Affiliation(s)
- Xiao-Tong Su
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - David H Ellison
- Division of Nephrology and Hypertension, School of Medicine, Oregon Health and Science University , Portland, Oregon
- Renal Section, Veterans Administration Portland Health Care System , Portland, Oregon
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
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30
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Evidence-based perioperative management of patients with high serum potassium level in resource-limited areas: A systematic review. INTERNATIONAL JOURNAL OF SURGERY OPEN 2019. [DOI: 10.1016/j.ijso.2019.10.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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31
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Kamel KS, Schreiber M, Halperin ML. Renal potassium physiology: integration of the renal response to dietary potassium depletion. Kidney Int 2018; 93:41-53. [PMID: 29102372 DOI: 10.1016/j.kint.2017.08.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 07/31/2017] [Accepted: 08/03/2017] [Indexed: 01/30/2023]
Abstract
We summarize the current understanding of the physiology of the renal handling of potassium (K+), and present an integrative view of the renal response to K+ depletion caused by dietary K+ restriction. This renal response involves contributions from different nephron segments, and aims to diminish the rate of excretion of K+ as a result of: decreasing the rate of electrogenic (and increasing the rate of electroneutral) reabsorption of sodium in the aldosterone-sensitive distal nephron (ASDN), decreasing the abundance of renal outer medullary K+ channels in the luminal membrane of principal cells in the ASDN, decreasing the flow rate in the ASDN, and increasing the reabsorption of K+ in the cortical and medullary collecting ducts. The implications of this physiology for the association between K+ depletion and hypertension, and K+ depletion and formation of calcium kidney stones are discussed.
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Affiliation(s)
- Kamel S Kamel
- Renal Division, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada; Keenan Research Center, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada.
| | - Martin Schreiber
- Renal Division, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Mitchell L Halperin
- Renal Division, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada; Keenan Research Center, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada
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32
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Palygin O, Pochynyuk O, Staruschenko A. Distal tubule basolateral potassium channels: cellular and molecular mechanisms of regulation. Curr Opin Nephrol Hypertens 2018; 27:373-378. [PMID: 29894319 PMCID: PMC6217967 DOI: 10.1097/mnh.0000000000000437] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PURPOSE OF REVIEW Multiple clinical and translational evidence support benefits of high potassium diet; however, there many uncertainties underlying the molecular and cellular mechanisms determining effects of dietary potassium. Kir4.1 and Kir5.1 proteins form a functional heteromer (Kir4.1/Kir5.1), which is the primary inwardly rectifying potassium channel on the basolateral membrane of both distal convoluted tubule (DCT) and the collecting duct principal cells. The purpose of this mini-review is to summarize latest advances in our understanding of the evolution, physiological relevance and mechanisms controlling these channels. RECENT FINDINGS Kir4.1 and Kir5.1 channels play a critical role in determining electrolyte homeostasis in the kidney and blood pressure, respectively. It was reported that Kir4.1/Kir5.1 serves as potassium sensors in the distal nephron responding to variations in dietary intake and hormonal stimuli. Global and kidney specific knockouts of either channel resulted in hypokalemia and severe cardiorenal phenotypes. Furthermore, knock out of Kir5.1 in Dahl salt-sensitive rat background revealed the crucial role of the Kir4.1/Kir5.1 channel in salt-induced hypertension. SUMMARY Here, we focus on reviewing novel experimental evidence of the physiological function, expression and hormonal regulation of renal basolateral inwardly rectifying potassium channels. Further investigation of molecular and cellular mechanisms controlling Kir4.1 and Kir4.1/Kir5.1-mediating pathways and development of specific compounds targeting these channels function is essential for proper control of electrolyte homeostasis and blood pressure.
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Affiliation(s)
- Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Oleh Pochynyuk
- Department of Integrative Biology, University of Texas Health Science Center, Houston, TX 77030
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Zhang DD, Gao ZX, Vio CP, Xiao Y, Wu P, Zhang H, Guo XW, Meng XX, Gu L, Wang JL, Duan XP, Lin DH, Wang WH, Gu R. Bradykinin Stimulates Renal Na + and K + Excretion by Inhibiting the K + Channel (Kir4.1) in the Distal Convoluted Tubule. Hypertension 2018; 72:361-369. [PMID: 29915013 PMCID: PMC6043363 DOI: 10.1161/hypertensionaha.118.11070] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 03/11/2018] [Accepted: 05/10/2018] [Indexed: 12/31/2022]
Abstract
Stimulation of BK2R (bradykinin [BK] B2 receptor) has been shown to increase renal Na+ excretion. The aim of the present study is to explore the role of BK2R in regulating Kir4.1 and NCC (NaCl cotransporter) in the distal convoluted tubule (DCT). Immunohistochemical studies demonstrated that BK2R was highly expressed in both apical and lateral membrane of Kir4.1-positive tubules, such as DCT. Patch-clamp experiments demonstrated that BK inhibited the basolateral 40-pS K+ channel (a Kir4.1/5.1 heterotetramer) in the DCT, and this effect was blocked by BK2R antagonist but not by BK1R (BK B1 receptor) antagonist. Whole-cell recordings also demonstrated that BK decreased the basolateral K+ conductance of the DCT and depolarized the membrane. Renal clearance experiments showed that BK increased urinary Na+ and K+ excretion. However, the BK-induced natriuretic effect was completely abolished in KS-Kir4.1 KO (kidney-specific conditional Kir4.1 knockout) mice, suggesting that Kir4.1 activity is required for BK-induced natriuresis. The continuous infusion of BK with osmotic pump for 3 days decreased the basolateral K+ conductance and the negativity of the DCT membrane. Western blot showed that infusion of BK decreased the expression of total NCC and phosphorylated NCC. Renal clearance experiments demonstrated that thiazide-induced natriuresis was blunted in the mice receiving BK infusion, suggesting that BK inhibited NCC function. Consequently, mice receiving BK infusion for 3 days were hypokalemic. We conclude that stimulation of BK2R inhibits NCC activity, increases urinary K+ excretion, and causes mice hypokalemia and that Kir4.1 is required for BK2R-mediated stimulation of urinary Na+ and K+ excretion.
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Affiliation(s)
- Dan-Dan Zhang
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Zhong-Xiuzi Gao
- Department of Pharmacology, New York Medical College, Valhalla, NY
| | - Carlos P Vio
- Center for Ageing and Regeneration Care-UC, Department of Physiology, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Yu Xiao
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Peng Wu
- Department of Pharmacology, New York Medical College, Valhalla, NY
| | - Hao Zhang
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Xi-Wen Guo
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Xin-Xin Meng
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Li Gu
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Jun-Lin Wang
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Xin-Peng Duan
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, NY
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, NY
| | - Ruimin Gu
- Department of Physiology, Harbin Medical University, Harbin, China
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Argaiz ER, Chavez-Canales M, Ostrosky-Frid M, Rodríguez-Gama A, Vázquez N, Gonzalez-Rodriguez X, Garcia-Valdes J, Hadchouel J, Ellison D, Gamba G. Kidney-specific WNK1 isoform (KS-WNK1) is a potent activator of WNK4 and NCC. Am J Physiol Renal Physiol 2018; 315:F734-F745. [PMID: 29846116 DOI: 10.1152/ajprenal.00145.2018] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Familial hyperkalemic hypertension (FHHt) can be mainly attributed to increased activity of the renal Na+:Cl- cotransporter (NCC), which is caused by altered expression and regulation of the with-no-lysine (K) 1 (WNK1) or WNK4 kinases. The WNK1 gene gives rise to a kidney-specific isoform that lacks the kinase domain (KS-WNK1), the expression of which occurs primarily in the distal convoluted tubule. The role played by KS-WNK1 in the modulation of the WNK/STE20-proline-alanine rich kinase (SPAK)/NCC pathway remains elusive. In the present study, we assessed the effect of human KS-WNK1 on NCC activity and on the WNK4-SPAK pathway. Microinjection of oocytes with human KS-WNK1 cRNA induces remarkable activation and phosphorylation of SPAK and NCC. The effect of KS-WNK1 was abrogated by eliminating a WNK-WNK-interacting domain and by a specific WNK inhibitor, WNK463, indicating that the activation of SPAK/NCC by KS-WNK1 is due to interaction with another WNK kinase. Under control conditions in oocytes, the activating serine 335 of the WNK4 T loop is not phosphorylated. In contrast, this serine becomes phosphorylated when the intracellular chloride concentration ([Cl-]i) is reduced or when KS-WNK1 is coexpressed with WNK4. KS-WNK1-mediated activation of WNK4 is not due to a decrease of the [Cl-]i. Coimmunoprecipitation analysis revealed that KS-WNK1 and WNK4 interact with each other and that WNK4 becomes autophosphorylated at serine 335 when it is associated with KS-WNK1. Together, these observations suggest that WNK4 becomes active in the presence of KS-WNK1, despite a constant [Cl-]i.
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Affiliation(s)
- Eduardo R Argaiz
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico.,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan Mexico City, Mexico.,Tecnológico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León , Mexico
| | - Maria Chavez-Canales
- INSERM UMRS1155, University Pierre and Marie Curie, Faculty of Medicine , Paris , France.,Translational Medicine Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Cardiología Ignacio Chávez, Tlalpan, México City, Mexico
| | - Mauricio Ostrosky-Frid
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan Mexico City, Mexico.,PECEM, Facultad de Medicina, Universidad Nacional Autónoma de México, Coyoacan, Mexico City, Mexico
| | - Alejandro Rodríguez-Gama
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico
| | - Norma Vázquez
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico.,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan Mexico City, Mexico
| | - Xochiquetzal Gonzalez-Rodriguez
- Departamento de Química Analítica, Facultad de Química, Universidad Nacional Autónoma de México, Coyoacan, Mexico City, Mexico
| | - Jesus Garcia-Valdes
- Departamento de Química Analítica, Facultad de Química, Universidad Nacional Autónoma de México, Coyoacan, Mexico City, Mexico
| | - Juliette Hadchouel
- INSERM UMRS1155, University Pierre and Marie Curie, Faculty of Medicine , Paris , France
| | - David Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University , Portland, Oregon.,Veterans Affairs Portland Health Care System, Portland, Oregon
| | - Gerardo Gamba
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico.,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan Mexico City, Mexico.,Tecnológico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León , Mexico
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35
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Kunizawa K, Hoshino J, Mizuno H, Suwabe T, Sumida K, Kawada M, Yamanouchi M, Sekine A, Hayami N, Hiramatsu R, Hasegawa E, Sawa N, Takaichi K, Shibata S, Ubara Y. Tolvaptan for Primary Aldosteronism and Autosomal Dominant Polycystic Kidney Disease: A Case Report. Case Rep Nephrol Dial 2018; 8:62-69. [PMID: 29692992 PMCID: PMC5903093 DOI: 10.1159/000487921] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 02/21/2018] [Indexed: 12/02/2022] Open
Abstract
A 59-year-old Japanese woman was admitted for evaluation of muscle weakness. Autosomal dominant polycystic kidney disease had been diagnosed at the age of 47 years, followed by primary aldosteronism at 53 years. At the age of 58, tolvaptan was started (60 mg/day) to treat her renal disease. After 8 months of tolvaptan therapy, hypokalemia-related muscle weakness became prominent, and hypertension became refractory. Finally, treatment with low-dose tolvaptan (30 mg/day) and high-dose spironolactone (100 mg/day) normalized serum potassium and the blood pressure. Tolvaptan can induce urinary excretion of potassium in patients with primary aldosteronism, and possible mechanisms are discussed.
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Affiliation(s)
- Kyohei Kunizawa
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan
| | - Junichi Hoshino
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan
| | - Hiroki Mizuno
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan
| | - Tatsuya Suwabe
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan
| | - Keiichi Sumida
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan
| | - Masahiro Kawada
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan
| | | | - Akinari Sekine
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan
| | - Noriko Hayami
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan
| | | | - Eiko Hasegawa
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan
| | - Naoki Sawa
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan
| | - Kenmei Takaichi
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan.,Okinaka Memorial Institute for Medical Research, Toranomon Hospital Kajigaya, Kawasaki, Japan
| | - Shigeru Shibata
- Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan
| | - Yoshifumi Ubara
- Nephrology Center, Toranomon Hospital Kajigaya, Kawasaki, Japan.,Okinaka Memorial Institute for Medical Research, Toranomon Hospital Kajigaya, Kawasaki, Japan
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36
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Wang MX, Cuevas CA, Su XT, Wu P, Gao ZX, Lin DH, McCormick JA, Yang CL, Wang WH, Ellison DH. Potassium intake modulates the thiazide-sensitive sodium-chloride cotransporter (NCC) activity via the Kir4.1 potassium channel. Kidney Int 2018; 93:893-902. [PMID: 29310825 PMCID: PMC6481177 DOI: 10.1016/j.kint.2017.10.023] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 10/04/2017] [Accepted: 10/12/2017] [Indexed: 12/14/2022]
Abstract
Kir4.1 in the distal convoluted tubule plays a key role in sensing plasma potassium and in modulating the thiazide-sensitive sodium-chloride cotransporter (NCC). Here we tested whether dietary potassium intake modulates Kir4.1 and whether this is essential for mediating the effect of potassium diet on NCC. High potassium intake inhibited the basolateral 40 pS potassium channel (a Kir4.1/5.1 heterotetramer) in the distal convoluted tubule, decreased basolateral potassium conductance, and depolarized the distal convoluted tubule membrane in Kcnj10flox/flox mice, herein referred to as control mice. In contrast, low potassium intake activated Kir4.1, increased potassium currents, and hyperpolarized the distal convoluted tubule membrane. These effects of dietary potassium intake on the basolateral potassium conductance and membrane potential in the distal convoluted tubule were completely absent in inducible kidney-specific Kir4.1 knockout mice. Furthermore, high potassium intake decreased, whereas low potassium intake increased the abundance of NCC expression only in the control but not in kidney-specific Kir4.1 knockout mice. Renal clearance studies demonstrated that low potassium augmented, while high potassium diminished, hydrochlorothiazide-induced natriuresis in control mice. Disruption of Kir4.1 significantly increased basal urinary sodium excretion but it abolished the natriuretic effect of hydrochlorothiazide. Finally, hypokalemia and metabolic alkalosis in kidney-specific Kir4.1 knockout mice were exacerbated by potassium restriction and only partially corrected by a high-potassium diet. Thus, Kir4.1 plays an essential role in mediating the effect of dietary potassium intake on NCC activity and potassium homeostasis.
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MESH Headings
- Alkalosis/genetics
- Alkalosis/metabolism
- Alkalosis/physiopathology
- Animals
- Disease Models, Animal
- Female
- Homeostasis
- Hydrochlorothiazide/pharmacology
- Hypokalemia/genetics
- Hypokalemia/metabolism
- Hypokalemia/physiopathology
- Kidney Tubules, Distal/drug effects
- Kidney Tubules, Distal/metabolism
- Kidney Tubules, Distal/physiopathology
- Male
- Membrane Potentials
- Mice, Knockout
- Natriuresis
- Potassium Channels, Inwardly Rectifying/deficiency
- Potassium Channels, Inwardly Rectifying/genetics
- Potassium Channels, Inwardly Rectifying/metabolism
- Potassium, Dietary/metabolism
- Renal Elimination
- Sodium/urine
- Sodium Chloride Symporter Inhibitors/pharmacology
- Solute Carrier Family 12, Member 3/genetics
- Solute Carrier Family 12, Member 3/metabolism
- Kir5.1 Channel
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Affiliation(s)
- Ming-Xiao Wang
- Department of Physiology, Zunyi Medical College, Zunyi, China; Department of Pharmacology, New York Medical College, Valhalla, New York, USA
| | - Catherina A Cuevas
- Department of Medicine, Oregon Health & Science University, Portland, Oregon, USA
| | - Xiao-Tong Su
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA
| | - Peng Wu
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA
| | - Zhong-Xiuzi Gao
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA
| | - James A McCormick
- Department of Medicine, Oregon Health & Science University, Portland, Oregon, USA
| | - Chao-Ling Yang
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA.
| | - David H Ellison
- Department of Medicine, Oregon Health & Science University, Portland, Oregon, USA.
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37
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Wu P, Gao ZX, Duan XP, Su XT, Wang MX, Lin DH, Gu R, Wang WH. AT2R (Angiotensin II Type 2 Receptor)-Mediated Regulation of NCC (Na-Cl Cotransporter) and Renal K Excretion Depends on the K Channel, Kir4.1. Hypertension 2018; 71:622-630. [PMID: 29483225 PMCID: PMC5843543 DOI: 10.1161/hypertensionaha.117.10471] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 10/26/2017] [Accepted: 12/21/2017] [Indexed: 02/02/2023]
Abstract
AT2R (AngII [angiotensin II] type 2 receptor) is expressed in the distal nephrons. The aim of the present study is to examine whether AT2R regulates NCC (Na-Cl cotransporter) and Kir4.1 of the distal convoluted tubule. AngII inhibited the basolateral 40 pS K channel (a Kir4.1/5.1 heterotetramer) in the distal convoluted tubule treated with losartan but not with PD123319. AT2R agonist also inhibits the K channel, indicating that AT2R was involved in tonic regulation of Kir4.1. The infusion of PD123319 stimulated the expression of tNCC (total NCC) and pNCC (phosphorylated NCC; Thr53) by a time-dependent way with the peak at 4 days. PD123319 treatment (4 days) stimulated the basolateral 40 pS K channel activity, augmented the basolateral K conductance, and increased the negativity of distal convoluted tubule membrane. The stimulation of Kir4.1 was essential for PD123319-induced increase in NCC because inhibiting AT2R increased the expression of tNCC and pNCC only in wild-type but not in the kidney-specific Kir4.1 knockout mice. Renal clearance study showed that thiazide-induced natriuretic effect was larger in PD123319-treated mice for 4 days than untreated mice. However, this effect was absent in kidney-specific Kir4.1 knockout mice which were also Na wasting under basal conditions. Finally, application of AT2R antagonist decreased the renal ability of K excretion and caused hyperkalemia in wild-type but not in kidney-specific Kir4.1 knockout mice. We conclude that AT2R-dependent regulation of NCC requires Kir4.1 in the distal convoluted tubule and that AT2R plays a role in stimulating K excretion by inhibiting Kir4.1 and NCC.
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Affiliation(s)
- Peng Wu
- From the Department of Pharmacology, New York Medical College, Valhalla (P.W., Z.-X.G., X.-T.S., M.-X.W., D.-H.L., W.-H.W.); and Department of Physiology, Harbin Medical University, China (X.-P.D., R.G.)
| | - Zhong-Xiuzi Gao
- From the Department of Pharmacology, New York Medical College, Valhalla (P.W., Z.-X.G., X.-T.S., M.-X.W., D.-H.L., W.-H.W.); and Department of Physiology, Harbin Medical University, China (X.-P.D., R.G.)
| | - Xin-Peng Duan
- From the Department of Pharmacology, New York Medical College, Valhalla (P.W., Z.-X.G., X.-T.S., M.-X.W., D.-H.L., W.-H.W.); and Department of Physiology, Harbin Medical University, China (X.-P.D., R.G.)
| | - Xiao-Tong Su
- From the Department of Pharmacology, New York Medical College, Valhalla (P.W., Z.-X.G., X.-T.S., M.-X.W., D.-H.L., W.-H.W.); and Department of Physiology, Harbin Medical University, China (X.-P.D., R.G.)
| | - Ming-Xiao Wang
- From the Department of Pharmacology, New York Medical College, Valhalla (P.W., Z.-X.G., X.-T.S., M.-X.W., D.-H.L., W.-H.W.); and Department of Physiology, Harbin Medical University, China (X.-P.D., R.G.)
| | - Dao-Hong Lin
- From the Department of Pharmacology, New York Medical College, Valhalla (P.W., Z.-X.G., X.-T.S., M.-X.W., D.-H.L., W.-H.W.); and Department of Physiology, Harbin Medical University, China (X.-P.D., R.G.)
| | - Ruimin Gu
- From the Department of Pharmacology, New York Medical College, Valhalla (P.W., Z.-X.G., X.-T.S., M.-X.W., D.-H.L., W.-H.W.); and Department of Physiology, Harbin Medical University, China (X.-P.D., R.G.)
| | - Wen-Hui Wang
- From the Department of Pharmacology, New York Medical College, Valhalla (P.W., Z.-X.G., X.-T.S., M.-X.W., D.-H.L., W.-H.W.); and Department of Physiology, Harbin Medical University, China (X.-P.D., R.G.).
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38
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Kleta R, Bockenhauer D. Salt-Losing Tubulopathies in Children: What's New, What's Controversial? J Am Soc Nephrol 2018; 29:727-739. [PMID: 29237739 PMCID: PMC5827598 DOI: 10.1681/asn.2017060600] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Renal tubulopathies provide insights into the inner workings of the kidney, yet also pose therapeutic challenges. Because of the central nature of sodium in tubular transport physiology, disorders of sodium handling may affect virtually all aspects of the homeostatic functions of the kidney. Yet, owing to the rarity of these disorders, little clinical evidence regarding treatment exists. Consequently, treatment can vary widely between individual physicians and centers and is based mainly on understanding of renal physiology, reported clinical observations, and individual experiences. Salt-losing tubulopathies can affect all tubular segments, from the proximal tubule to the collecting duct. But the more frequently observed disorders are Bartter and Gitelman syndrome, which affect salt transport in the thick ascending limb of Henle's loop and/or the distal convoluted tubule, and these disorders generate the greatest controversies regarding management. Here, we review clinical and molecular aspects of salt-losing tubulopathies and discuss novel insights provided mainly by genetic investigations and retrospective clinical reviews. Additionally, we discuss controversial topics in the management of these disorders to highlight areas of importance for future clinical trials. International collaboration will be required to perform clinical studies to inform the treatment of these rare disorders.
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Affiliation(s)
- Robert Kleta
- UCL Centre for Nephrology and Great Ormond Street Hospital NHS Foundation Trust, London, United Kingdom
| | - Detlef Bockenhauer
- UCL Centre for Nephrology and Great Ormond Street Hospital NHS Foundation Trust, London, United Kingdom
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39
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Terker AS, Castañeda-Bueno M, Ferdaus MZ, Cornelius RJ, Erspamer KJ, Su XT, Miller LN, McCormick JA, Wang WH, Gamba G, Yang CL, Ellison DH. With no lysine kinase 4 modulates sodium potassium 2 chloride cotransporter activity in vivo. Am J Physiol Renal Physiol 2018; 315:F781-F790. [PMID: 29412704 DOI: 10.1152/ajprenal.00485.2017] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
With no lysine kinase 4 (WNK4) is essential to activate the thiazide-sensitive NaCl cotransporter (NCC) along the distal convoluted tubule, an effect central to the phenotype of familial hyperkalemic hypertension. Although effects on potassium and sodium channels along the connecting and collecting tubules have also been documented, WNK4 is typically believed to have little role in modulating sodium chloride reabsorption along the thick ascending limb of the loop of Henle. Yet wnk4-/- mice (knockout mice lacking WNK4) do not demonstrate the hypocalciuria typical of pure distal convoluted tubule dysfunction. Here, we tested the hypothesis that WNK4 also modulates bumetanide-sensitive Na-K-2Cl cotransporter (NKCC2) function along the thick ascending limb. We confirmed that w nk4-/- mice are hypokalemic and waste sodium chloride, but are also normocalciuric. Results from Western blots suggested that the phosphorylated forms of both NCC and NKCC2 were in lower abundance in wnk4-/- mice than in controls. This finding was confirmed by immunofluorescence microscopy. Although the initial response to furosemide was similar in wnk4-/- mice and controls, the response was lower in the knockout mice when reabsorption along the distal convoluted tubule was inhibited. Using HEK293 cells, we showed that WNK4 increases the abundance of phosphorylated NKCC2. More supporting evidence that WNK4 may modulate NKCC2 emerges from a mouse model of WNK4-mediated familial hyperkalemic hypertension in which more phosphorylated NKCC2 is present than in controls. These data indicate that WNK4, in addition to modulating NCC, also modulates NKCC2, contributing to its physiological function in vivo.
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Affiliation(s)
- Andrew S Terker
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Maria Castañeda-Bueno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , Mexico City, Mexico
| | - Mohammed Z Ferdaus
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Ryan J Cornelius
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Kayla J Erspamer
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Xiao-Tong Su
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Lauren N Miller
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - James A McCormick
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Gerardo Gamba
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , Mexico City, Mexico.,Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma University de México , Mexico City, Mexico.,Tecnológico de Monterrey, Escuela de Medicina y de Ciencias de la Salud, Monterrey, México
| | - Chao-Ling Yang
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - David H Ellison
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
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40
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West CA, Welling PA, West DA, Coleman RA, Cheng KY, Chen C, DuBose TD, Verlander JW, Baylis C, Gumz ML. Renal and colonic potassium transporters in the pregnant rat. Am J Physiol Renal Physiol 2018; 314:F251-F259. [PMID: 29046297 PMCID: PMC5866449 DOI: 10.1152/ajprenal.00288.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 10/11/2017] [Accepted: 10/11/2017] [Indexed: 11/22/2022] Open
Abstract
Gestational potassium retention, most of which occurs during late pregnancy, is essential for fetal development. The purpose of this study was to examine mechanisms underlying changes in potassium handling by the kidney and colon in pregnancy. We found that potassium intake and renal excretion increased in late pregnancy while fecal potassium excretion remained unchanged and that pregnant rats exhibited net potassium retention. By quantitative PCR we found markedly increased H+-K+-ATPase type 2 (HKA2) mRNA expression in the cortex and outer medullary of late pregnant vs. virgin. Renal outer medullary potassium channel (ROMK) mRNA was unchanged in the cortex, but apical ROMK abundance (by immunofluorescence) was decreased in pregnant vs. virgin in the distal convoluted tubule (DCT) and connecting tubule (CNT). Big potassium-α (BKα) channel-α protein abundance in intercalated cells in the cortex and outer medullary collecting ducts (by immunohistochemistry) fell in late pregnancy. In the distal colon we found increased HKA2 mRNA and protein abundance (Western blot) and decreased BKα protein with no observed changes in mRNA. Therefore, the potassium retention of pregnancy is likely to be due to increased collecting duct potassium reabsorption (via increased HKA2), decreased potassium secretion (via decreased ROMK and BK), as well as increased colonic reabsorption via HKA2.
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Affiliation(s)
- Crystal A West
- Department of Medicine, Georgetown University, Washington, District of Columiba
| | - Paul A Welling
- Department of Physiology, University of Maryland School of Medicine , Baltimore, Maryland
| | - David A West
- Department of Medicine, Georgetown University, Washington, District of Columiba
| | - Richard A Coleman
- Department of Physiology, University of Maryland School of Medicine , Baltimore, Maryland
| | - Kit-Yan Cheng
- Department of Medicine, University of Florida , Gainesville, Florida
| | - Chao Chen
- Department of Medicine, University of Florida , Gainesville, Florida
| | - Thomas D DuBose
- Department of Medicine, Wake Forest School of Medicine , Winston-Salem, North Carolina
| | - Jill W Verlander
- Department of Medicine, University of Florida , Gainesville, Florida
| | - Chris Baylis
- Department of Medicine, University of Florida , Gainesville, Florida
- Department of Physiology and Functional Genomics, University of Florida , Gainesville, Florida
| | - Michelle L Gumz
- Department of Medicine, University of Florida , Gainesville, Florida
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41
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New Therapeutic Approaches for the Treatment of Hyperkalemia in Patients Treated with Renin-Angiotensin-Aldosterone System Inhibitors. Cardiovasc Drugs Ther 2018; 32:99-119. [DOI: 10.1007/s10557-017-6767-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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42
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Ferdaus MZ, McCormick JA. Mechanisms and controversies in mutant Cul3-mediated familial hyperkalemic hypertension. Am J Physiol Renal Physiol 2018; 314:F915-F920. [PMID: 29361671 DOI: 10.1152/ajprenal.00593.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Autosomal dominant mutations in cullin-3 ( Cul3) cause the most severe form of familial hyperkalemic hypertension (FHHt). Cul3 mutations cause skipping of exon 9, which results in an internal deletion of 57 amino acids from the CUL3 protein (CUL3-∆9). The precise mechanism by which this altered form of CUL3 causes FHHt is controversial. CUL3 is a member of the cullin-RING ubiquitin ligase family that mediates ubiquitination and thus degradation of cellular proteins, including with-no-lysine [K] kinases (WNKs). In CUL3-∆9-mediated FHHt, proteasomal degradation of WNKs is abrogated, leading to overactivation of the WNK targets sterile 20/SPS-1 related proline/alanine-rich kinase and oxidative stress-response kinase-1, which directly phosphorylate and activate the thiazide-sensitive Na+-Cl- cotransporter. Several groups have suggested different mechanisms by which CUL3-∆9 causes FHHt. The majority of these are derived from in vitro data, but recently the Kurz group (Schumacher FR, Siew K, Zhang J, Johnson C, Wood N, Cleary SE, Al Maskari RS, Ferryman JT, Hardege I, Figg NL, Enchev R, Knebel A, O'Shaughnessy KM, Kurz T. EMBO Mol Med 7: 1285-1306, 2015) described the first mouse model of CUL3-∆9-mediated FHHt. Analysis of this model suggested that CUL3-∆9 is degraded in vivo, and thus Cul3 mutations cause FHHt by inducing haploinsufficiency. We recently directly tested this model but found that other dominant effects of CUL3-∆9 must contribute to the development of FHHt. In this review, we focus on our current knowledge of CUL3-∆9 action gained from in vitro and in vivo models that may help unravel this complex problem.
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Affiliation(s)
- Mohammed Z Ferdaus
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University , Portland, Oregon
| | - James A McCormick
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University , Portland, Oregon
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43
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Ferdaus MZ, Miller LN, Agbor LN, Saritas T, Singer JD, Sigmund CD, McCormick JA. Mutant Cullin 3 causes familial hyperkalemic hypertension via dominant effects. JCI Insight 2017; 2:96700. [PMID: 29263298 DOI: 10.1172/jci.insight.96700] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 11/15/2017] [Indexed: 11/17/2022] Open
Abstract
Mutations in the ubiquitin ligase scaffold protein Cullin 3 (CUL3) cause the disease familial hyperkalemic hypertension (FHHt). In the kidney, mutant CUL3 (CUL3-Δ9) increases abundance of With-No-Lysine [K] Kinase 4 (WNK4), with excessive activation of the downstream Sterile 20 (STE20)/SPS-1-related proline/alanine-rich kinase (SPAK) increasing phosphorylation of the Na+-Cl- cotransporter (NCC). CUL3-Δ9 promotes its own degradation via autoubiquitination, leading to the hypothesis that Cul3 haploinsufficiency causes FHHt. To directly test this, we generated Cul3 heterozygous mice (CUL3-Het), and Cul3 heterozygotes also expressing CUL3-Δ9 (CUL3-Het/Δ9), using an inducible renal epithelial-specific system. Endogenous CUL3 was reduced to 50% in both models, and consistent with autoubiquitination, CUL3-Δ9 protein was undetectable in CUL3-Het/Δ9 kidneys unless primary renal epithelia cells were cultured. Abundances of WNK4 and phosphorylated NCC did not differ between control and CUL3-Het mice, but they were elevated in CUL3-Het/Δ9 mice, which also displayed higher plasma [K+] and blood pressure. Abundance of phosphorylated Na+-K+-2Cl- cotransporter (NKCC2) was also increased, which may contribute to the severity of CUL3-Δ9-mediated FHHt. WNK4 and SPAK localized to puncta in NCC-positive segments but not in NKCC2-positive segments, suggesting differential effects of CUL3-Δ9. These results indicate that Cul3 haploinsufficiency does not cause FHHt, but dominant effects of CUL3-Δ9 are required.
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Affiliation(s)
- Mohammed Z Ferdaus
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon, USA
| | - Lauren N Miller
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon, USA
| | - Larry N Agbor
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Turgay Saritas
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon, USA
| | - Jeffrey D Singer
- Department of Biology, Portland State University, Portland, Oregon, USA
| | - Curt D Sigmund
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.,UIHC Center for Hypertension Research, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - James A McCormick
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon, USA
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44
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Potassium regulation in the neonate. Pediatr Nephrol 2017; 32:2037-2049. [PMID: 28378030 DOI: 10.1007/s00467-017-3635-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 02/13/2017] [Accepted: 02/21/2017] [Indexed: 10/19/2022]
Abstract
Potassium, the major cation in intracelluar fluids, is essential for vital biological functions. Neonates maintain a net positive potassium balance, which is fundamental to ensure somatic growth but places these infants, especially those born prematurely, at risk for life-threatening disturbances in potassium concentration [K+] in the extracellular fluid compartment. Potassium conservation is achieved by maximizing gastrointestinal absorption and minimizing renal losses. A markedly low glomerular filtration rate, plus adaptations in tubular transport along the nephron, result in low potassium excretion in the urine of neonates. Careful evaluation of clinical data using reference values that are normal for the neonate's postmenstrual age is critical to avoid over-treating infants with laboratory results that represent physiologic values for their developmental stage. The treatment should be aimed at correcting the primary cause when possible. Alterations in the levels or sensitivity to aldosterone are common in neonates. In symptomatic patients, the disturbances in [K+] should be corrected promptly, with close electrocardiographic monitoring. Plasma [K+] should be monitored during the first 72 h of life in all premature infants born before 30 weeks of postmenstrual age as these infants are prone to develop non-oliguric hyperkalemia with potential serious complications.
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45
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McNicholas BA, Pham MH, Carli K, Chen CH, Colobong-Smith N, Anderson AE, Pham H. Treatment of Hyperkalemia With a Low-Dose Insulin Protocol Is Effective and Results in Reduced Hypoglycemia. Kidney Int Rep 2017; 3:328-336. [PMID: 29725636 PMCID: PMC5932119 DOI: 10.1016/j.ekir.2017.10.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/13/2017] [Accepted: 10/16/2017] [Indexed: 12/26/2022] Open
Abstract
Introduction Complications associated with insulin treatment for hyperkalemia are serious and common. We hypothesize that, in chronic kidney disease (CKD) and end-stage renal disease (ESRD), giving 5 units instead of 10 units of i.v. regular insulin may reduce the risk of causing hypoglycemia when treating hyperkalemia. Methods A retrospective quality improvement study on hyperkalemia management (K+ ≥ 6 mEq/l) from June 2013 through December 2013 was conducted at an urban emergency department center. Electronic medical records were reviewed, and data were extracted on presentation, management of hyperkalemia, incidence and timing of hypoglycemia, and whether treatment was ordered as a protocol through computerized physician order entry (CPOE). We evaluated whether an educational effort to encourage the use of a protocol through CPOE that suggests the use of 5 units might be beneficial for CKD/ESRD patients. A second audit of hyperkalemia management from July 2015 through January 2016 was conducted to assess the effects of intervention on hypoglycemia incidence. Results Treatments ordered using a protocol for hyperkalemia increased following the educational intervention (58 of 78 patients [74%] vs. 62 of 99 patients [62%]), and the number of CKD/ESRD patients prescribed 5 units of insulin as per protocol increased (30 of 32 patients [93%] vs. 32 of 43 [75%], P = .03). Associated with this, the incidence of hypoglycemia associated with insulin treatment was lower (7 of 63 patients [11%] vs. 22 of 76 patients [28%], P = .03), and there were no cases of severe hypoglycemia compared to the 3 cases before the intervention. Conclusion Education on the use of a protocol for hyperkalemia resulted in a reduction in the number of patients with severe hypoglycemia associated with insulin treatment.
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Affiliation(s)
- Bairbre A. McNicholas
- Division of Nephrology, University of Washington, Seattle, Washington, USA
- Department of Intensive Care Medicine, Saolta Hospital Groups, Galway University Hospitals, Newcastle Road, Galway, Ireland
- Correspondence: Bairbre McNicholas, Department of Intensive Care Medicine, Saolta Hospital Groups, Galway University Hospital, Newcastle Road, Galway, H91 YR71, Ireland.
| | - Mai H. Pham
- Division of Nephrology, University of Washington, Seattle, Washington, USA
| | - Katrina Carli
- Division of Nephrology, University of Washington, Seattle, Washington, USA
| | - Chang Huei Chen
- Division of Nephrology, University of Washington, Seattle, Washington, USA
| | | | | | - Hien Pham
- Division of Nephrology, University of Washington, Seattle, Washington, USA
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46
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Kovesdy CP, Appel LJ, Grams ME, Gutekunst L, McCullough PA, Palmer BF, Pitt B, Sica DA, Townsend RR. Potassium homeostasis in health and disease: A scientific workshop cosponsored by the National Kidney Foundation and the American Society of Hypertension. ACTA ACUST UNITED AC 2017; 11:783-800. [PMID: 29030153 DOI: 10.1016/j.jash.2017.09.011] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 09/08/2017] [Accepted: 09/08/2017] [Indexed: 12/16/2022]
Abstract
While much emphasis, and some controversy, centers on recommendations for sodium intake, there has been considerably less interest in recommendations for dietary potassium intake, in both the general population and patients with medical conditions, particularly acute and chronic kidney disease. Physiology literature and cohort studies have noted that the relative balance in sodium and potassium intakes is an important determinant of many of the sodium-related outcomes. A noteworthy characteristic of potassium in clinical medicine is the extreme concern shared by many practitioners when confronted by a patient with hyperkalemia. Fear of this often asymptomatic finding limits enthusiasm for recommending potassium intake and often limits the use of renin-angiotensin-aldosterone system blockers in patients with heart failure and chronic kidney diseases. New agents for managing hyperkalemia may alter the long-term management of heart failure and the hypertension, proteinuria, and further function loss in chronic kidney diseases. In this jointly sponsored effort between the American Society of Hypertension and the National Kidney Foundation, 3 panels of researchers and practitioners from various disciplines discussed and summarized current understanding of the role of potassium in health and disease, focusing on cardiovascular, nutritional, and kidney considerations associated with both hypo- and hyperkalemia.
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Affiliation(s)
| | | | - Morgan E Grams
- Johns Hopkins University School of Medicine, Baltimore, MD
| | - Lisa Gutekunst
- Suburban Dialysis, Williamsville, NY; Davita, Inc, Denver, CO
| | - Peter A McCullough
- Baylor University Medical Center, Baylor Heart and Vascular Institute, Baylor Jack and Jane Hamilton Heart and Vascular Hospital, Dallas, TX; The Heart Hospital, Plano, TX
| | - Biff F Palmer
- University of Texas Southwestern Medical Center, Dallas, TX
| | - Bertram Pitt
- University of Michigan School of Medicine, Ann Arbor, MI
| | | | - Raymond R Townsend
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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47
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Kovesdy CP, Appel LJ, Grams ME, Gutekunst L, McCullough PA, Palmer BF, Pitt B, Sica DA, Townsend RR. Potassium Homeostasis in Health and Disease: A Scientific Workshop Cosponsored by the National Kidney Foundation and the American Society of Hypertension. Am J Kidney Dis 2017; 70:844-858. [PMID: 29029808 DOI: 10.1053/j.ajkd.2017.09.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 09/08/2017] [Indexed: 12/31/2022]
Abstract
While much emphasis, and some controversy, centers on recommendations for sodium intake, there has been considerably less interest in recommendations for dietary potassium intake, in both the general population and patients with medical conditions, particularly acute and chronic kidney disease. Physiology literature and cohort studies have noted that the relative balance in sodium and potassium intakes is an important determinant of many of the sodium-related outcomes. A noteworthy characteristic of potassium in clinical medicine is the extreme concern shared by many practitioners when confronted by a patient with hyperkalemia. Fear of this often asymptomatic finding limits enthusiasm for recommending potassium intake and often limits the use of renin-angiotensin-aldosterone system blockers in patients with heart failure and chronic kidney diseases. New agents for managing hyperkalemia may alter the long-term management of heart failure and the hypertension, proteinuria, and further function loss in chronic kidney diseases. In this jointly sponsored effort between the American Society of Hypertension and the National Kidney Foundation, 3 panels of researchers and practitioners from various disciplines discussed and summarized current understanding of the role of potassium in health and disease, focusing on cardiovascular, nutritional, and kidney considerations associated with both hypo- and hyperkalemia.
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Affiliation(s)
| | | | - Morgan E Grams
- Johns Hopkins University School of Medicine, Baltimore, MD
| | - Lisa Gutekunst
- Suburban Dialysis, Williamsville, NY; Davita, Inc, Denver, CO
| | - Peter A McCullough
- Baylor University Medical Center, Baylor Heart and Vascular Institute, Baylor Jack and Jane Hamilton Heart and Vascular Hospital, Dallas, TX; The Heart Hospital, Plano, TX
| | - Biff F Palmer
- University of Texas Southwestern Medical Center, Dallas, TX
| | - Bertram Pitt
- University of Michigan School of Medicine, Ann Arbor, MI
| | | | - Raymond R Townsend
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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48
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Palygin O, Levchenko V, Ilatovskaya DV, Pavlov TS, Pochynyuk OM, Jacob HJ, Geurts AM, Hodges MR, Staruschenko A. Essential role of Kir5.1 channels in renal salt handling and blood pressure control. JCI Insight 2017; 2:92331. [PMID: 28931751 PMCID: PMC5621918 DOI: 10.1172/jci.insight.92331] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 08/08/2017] [Indexed: 01/07/2023] Open
Abstract
Supplementing diets with high potassium helps reduce hypertension in humans. Inwardly rectifying K+ channels Kir4.1 (Kcnj10) and Kir5.1 (Kcnj16) are highly expressed in the basolateral membrane of distal renal tubules and contribute to Na+ reabsorption and K+ secretion through the direct control of transepithelial voltage. To define the importance of Kir5.1 in blood pressure control under conditions of salt-induced hypertension, we generated a Kcnj16 knockout in Dahl salt-sensitive (SS) rats (SSKcnj16-/-). SSKcnj16-/- rats exhibited hypokalemia and reduced blood pressure, and when fed a high-salt diet (4% NaCl), experienced 100% mortality within a few days triggered by salt wasting and severe hypokalemia. Electrophysiological recordings of basolateral K+ channels in the collecting ducts isolated from SSKcnj16-/- rats revealed activity of only homomeric Kir4.1 channels. Kir4.1 expression was upregulated in SSKcnj16-/- rats, but the protein was predominantly localized in the cytosol in SSKcnj16-/- rats. Benzamil, but not hydrochlorothiazide or furosemide, rescued this phenotype from mortality on a high-salt diet. Supplementation of high-salt diet with increased potassium (2% KCl) prevented mortality in SSKcnj16-/- rats and prevented or mitigated hypertension in SSKcnj16-/- or control SS rats, respectively. Our results demonstrate that Kir5.1 channels are key regulators of renal salt handling in SS hypertension.
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Affiliation(s)
- Oleg Palygin
- Department of Physiology and
- Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | | | | | | | - Oleh M. Pochynyuk
- Department of Integrative Biology, University of Texas Health Science Center Medical School, Houston, Texas, USA
| | - Howard J. Jacob
- Department of Physiology and
- Human and Molecular Genetics Center and
| | - Aron M. Geurts
- Department of Physiology and
- Human and Molecular Genetics Center and
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Matthew R. Hodges
- Department of Physiology and
- Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Alexander Staruschenko
- Department of Physiology and
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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49
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Raikwar NS, Thomas CP. Aldosterone regulates a 5' variant sgk1 transcript via a shared hormone response element in the sgk1 5' regulatory region. Physiol Rep 2017; 5:5/7/e13221. [PMID: 28408636 PMCID: PMC5392512 DOI: 10.14814/phy2.13221] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Revised: 02/20/2017] [Accepted: 02/21/2017] [Indexed: 11/24/2022] Open
Abstract
We previously identified a 5ʹ variant alternate transcript of Sgk1 (Sgk1_v3) encoding an NH2‐terminal variant Sgk1 isoform, Sgk1_i3 that, like Sgk1, is expressed in the distal convoluted tubule, connecting tubule and collecting duct and can stimulate epithelial Na+ transport (Am J Physiol Renal Physiol 303: F1527–F1533, 2012). We now demonstrate that, similar to Sgk1, aldosterone and glucocorticoids stimulate Sgk1_v3 expression in cell lines from the collecting duct and airway epithelia. In mice, short term aldosterone infusion and maneuvers that increase endogenous aldosterone secretion including dietary Na+ deprivation and K+ loading increases distal nephron Sgk1_v3 expression in vivo. Although Sgk1_v3 has a different 5ʹ proximal regulatory region from Sgk1, the transcription start sites are less than 1000 bp apart. We cloned the 5ʹ regulatory region for Sgk1 and Sgk_v3 upstream of a luciferase gene and by deletion and reporter gene analysis we localized the corticosteroid regulatory region for Sgk1_v3 to a glucocorticoid response element (GRE) that had previously been identified for Sgk1 (Am J Physiol Endo Metab 283: E971–E979, 2002). We tested this element with MR in an MR‐null cell line and demonstrate that aldosterone stimulates Sgk1 and Sgk1_v3 via this GRE. We conclude that corticosteroids stimulate Sgk1 and Sgk1_v3 expression in epithelial cells via activation of a common conserved GRE in the 5ʹ flanking region of Sgk1.
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Affiliation(s)
- Nandita S Raikwar
- Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, Iowa
| | - Christie P Thomas
- Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, Iowa .,The Graduate Program in Molecular Biology, University of Iowa College of Medicine, Iowa City, Iowa.,The Veterans Affairs Medical Center, Iowa City, Iowa
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50
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McDonough AA, Veiras LC, Guevara CA, Ralph DL. Cardiovascular benefits associated with higher dietary K + vs. lower dietary Na +: evidence from population and mechanistic studies. Am J Physiol Endocrinol Metab 2017; 312:E348-E356. [PMID: 28174181 PMCID: PMC5406991 DOI: 10.1152/ajpendo.00453.2016] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 01/26/2017] [Accepted: 02/03/2017] [Indexed: 12/24/2022]
Abstract
The World Health Organization ranks hypertension the leading global risk factor for disease, specifically, cardiovascular disease. Blood pressure (BP) is higher in Westernized populations consuming Na+-rich processed foods than in isolated societies consuming K+-rich natural foods. Evidence suggests that lowering dietary Na+ is particularly beneficial in hypertensive individuals who consume a high-Na+ diet. Nonetheless, numerous population studies demonstrate a relationship between higher dietary K+, estimated from urinary excretion or dietary recall, and lower BP, regardless of Na+ intake. Interventional studies with K+ supplementation suggest that it provides a direct benefit; K+ may also be a marker for other beneficial components of a "natural" diet. Recent studies in rodent models indicate mechanisms for the K+ benefit: the distal tubule Na+-Cl- cotransporter (NCC) controls Na+ delivery downstream to the collecting duct, where Na+ reabsorbed by epithelial Na+ channels drives K+ secretion and excretion through K+ channels in the same region. High dietary K+ provokes a decrease in NCC activity to drive more K+ secretion (and Na+ excretion, analogous to the actions of a thiazide diuretic) whether Na+ intake is high or low; low dietary K+ provokes an increase in NCC activity and Na+ retention, also independent of dietary Na+ Together, the findings suggest that public health efforts directed toward increasing consumption of K+-rich natural foods would reduce BP and, thus, cardiovascular and kidney disease.
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Affiliation(s)
- Alicia A McDonough
- Department of Cell and Neurobiology, Keck School of Medicine of the University of Southern California, Los Angeles, California
| | - Luciana C Veiras
- Department of Cell and Neurobiology, Keck School of Medicine of the University of Southern California, Los Angeles, California
| | - Claire A Guevara
- Department of Cell and Neurobiology, Keck School of Medicine of the University of Southern California, Los Angeles, California
| | - Donna L Ralph
- Department of Cell and Neurobiology, Keck School of Medicine of the University of Southern California, Los Angeles, California
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