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Duan XP, Zhang CB, Wang WH, Lin DH. Role of calcineurin in regulating renal potassium (K +) excretion: Mechanisms of calcineurin inhibitor-induced hyperkalemia. Acta Physiol (Oxf) 2024; 240:e14189. [PMID: 38860527 PMCID: PMC11250626 DOI: 10.1111/apha.14189] [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: 03/21/2024] [Revised: 05/28/2024] [Accepted: 05/30/2024] [Indexed: 06/12/2024]
Abstract
Calcineurin, protein phosphatase 2B (PP2B) or protein phosphatase 3 (PP3), is a calcium-dependent serine/threonine protein phosphatase. Calcineurin is widely expressed in the kidney and regulates renal Na+ and K+ transport. In the thick ascending limb, calcineurin plays a role in inhibiting NKCC2 function by promoting the dephosphorylation of the cotransporter and an intracellular sorting receptor, called sorting-related-receptor-with-A-type repeats (SORLA), is involved in modulating the effect of calcineurin on NKCC2. Calcineurin also participates in regulating thiazide-sensitive NaCl-cotransporter (NCC) in the distal convoluted tubule. The mechanisms by which calcineurin regulates NCC include directly dephosphorylation of NCC, regulating Kelch-like-3/CUL3 E3 ubiquitin-ligase complex, which is responsible for WNK (with-no-lysin-kinases) ubiquitination, and inhibiting Kir4.1/Kir5.1, which determines NCC expression/activity. Finally, calcineurin is also involved in regulating ROMK (Kir1.1) channels in the cortical collecting duct and Cyp11 2 expression in adrenal zona glomerulosa. In summary, calcineurin is involved in the regulation of NKCC2, NCC, and inwardly rectifying K+ channels in the kidney, and it also plays a role in modulating aldosterone synthesis in adrenal gland, which regulates epithelial-Na+-channel expression/activity. Thus, application of calcineurin inhibitors (CNIs) is expected to abrupt calcineurin-mediated regulation of transepithelial Na+ and K+ transport in the kidney. Consequently, CNIs cause hypertension, compromise renal K+ excretion, and induce hyperkalemia.
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Affiliation(s)
- Xin-Peng Duan
- Department of Physiology, Xuzhou Medical University, Xuzhou, China
| | - Cheng-Biao Zhang
- Department of Physiology, Xuzhou Medical University, Xuzhou, China
- 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
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA
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2
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Rioux AV, Nsimba-Batomene TR, Slimani S, Bergeron NAD, Gravel MAM, Schreiber SV, Fiola MJ, Haydock L, Garneau AP, Isenring P. Navigating the multifaceted intricacies of the Na +-Cl - cotransporter, a highly regulated key effector in the control of hydromineral homeostasis. Physiol Rev 2024; 104:1147-1204. [PMID: 38329422 DOI: 10.1152/physrev.00027.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 01/01/2024] [Accepted: 02/03/2024] [Indexed: 02/09/2024] Open
Abstract
The Na+-Cl- cotransporter (NCC; SLC12A3) is a highly regulated integral membrane protein that is known to exist as three splice variants in primates. Its primary role in the kidney is to mediate the cosymport of Na+ and Cl- across the apical membrane of the distal convoluted tubule. Through this role and the involvement of other ion transport systems, NCC allows the systemic circulation to reclaim a fraction of the ultrafiltered Na+, K+, Cl-, and Mg+ loads in exchange for Ca2+ and [Formula: see text]. The physiological relevance of the Na+-Cl- cotransport mechanism in humans is illustrated by several abnormalities that result from NCC inactivation through the administration of thiazides or in the setting of hereditary disorders. The purpose of the present review is to discuss the molecular mechanisms and overall roles of Na+-Cl- cotransport as the main topics of interest. On reading the narrative proposed, one will realize that the knowledge gained in regard to these themes will continue to progress unrelentingly no matter how refined it has now become.
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Affiliation(s)
- A V Rioux
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
| | - T R Nsimba-Batomene
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
| | - S Slimani
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
| | - N A D Bergeron
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
| | - M A M Gravel
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
| | - S V Schreiber
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
| | - M J Fiola
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
| | - L Haydock
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
- Service de Néphrologie-Transplantation Rénale Adultes, Hôpital Necker-Enfants Malades, AP-HP, INSERM U1151, Université Paris Cité, Paris, France
| | - A P Garneau
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
- Service de Néphrologie-Transplantation Rénale Adultes, Hôpital Necker-Enfants Malades, AP-HP, INSERM U1151, Université Paris Cité, Paris, France
| | - P Isenring
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Quebec, Canada
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3
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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 2024:00001751-990000000-00330. [PMID: 38788191 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 intakeinduced 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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Joshi A, Kaur S, Taneja SK, Mandal R. Review Article on Molecular Mechanism of Regulation of Hypertension by Macro-elements (Na, K, Ca and Mg), Micro-elements/Trace Metals (Zn and Cu) and Toxic Elements (Pb and As). Biol Trace Elem Res 2024; 202:1477-1502. [PMID: 37523058 DOI: 10.1007/s12011-023-03784-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Accepted: 07/16/2023] [Indexed: 08/01/2023]
Abstract
Hypertension (HT) is a medical condition arising due to increase in blood pressure (BP) prevalent worldwide. The balanced dietary intakes of macro-elements and micro-elements including Na, K, Ca, Mg, Zn, and Cu have been described to maintain BP in humans by regulating the osmolarity of blood, cells/tissues, prevention of generation of oxidative and nitrosative stress (OANS), and endothelial damage through their functioning as important components of renin-angiotensin-aldosterone system (RAAS), antioxidant enzyme defense system, and maintenance of blood vascular-endothelial and vascular smooth muscle cell (VSMC) functions. However, inadequate/excess dietary intakes of Na/K, Ca/Mg, and Zn/Cu along with higher Pb and As exposures recognized to induce HT through common mechanisms including the followings: endothelial dysfunctions due to impairment of vasodilatation, increased vasoconstriction and arterial stiffness, blood clotting, inflammation, modification of sympathetic activity and higher catecholamine release, increased peripheral vascular resistance, and cardiac output; increased OANS due to reduced and elevated activities of extracellular superoxide dismutase and NAD(P)H oxidase, less nitric oxide bioavailability, decrease in cGMP and guanylate cyclase activity, increase in intracellular Ca2+ ions in VSMCs, and higher pro-inflammatory cytokines; higher parathyroid and calcitriol hormones; activation/suppression of RAAS resulting imbalance in blood Na+, K+, and water regulated by renin, angiotensin II, and aldosterone through affecting natriuresis/kaliuresis/diuresis; elevation in serum cholesterol and LDL cholesterol, decrease in HDL cholesterol due to defect in lipoprotein metabolism. The present study recommends the need to review simple dietary mineral intervention studies/supplementation trials before keeping their individual dietary excess intakes/exposures in consideration because their interactions lead to elevation and fall of their concentrations in body affecting onset of HT.
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Affiliation(s)
- Amit Joshi
- PG Department of Biotechnology and Microbial Biotechnology, Sri Guru Gobind Singh College, Sector-26, Chandigarh, UT, India
| | - Sukhbir Kaur
- Department of Zoology, Panjab University, Sector-14, Chandigarh, UT, India
| | | | - Reshu Mandal
- PG Department of Zoology, Sri Guru Gobind Singh College, Sector-26, Chandigarh, UT, India.
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Abstract
Excessive salt intake raises blood pressure, but the implications of this observation for human health have remained contentious. It has also been recognized for many years that potassium intake may mitigate the effects of salt intake on blood pressure and possibly on outcomes such as stroke. Recent large randomized intervention trials have provided strong support for the benefits of replacing salt (NaCl) with salt substitute (75% NaCl, 25% KCl) on hard outcomes, including stroke. During the same period of time, major advances have been made in understanding how the body senses and tastes salt, and how these sensations drive intake. Additionally, new insights into the complex interactions between systems that control sodium and potassium excretion by the kidneys, and the brain have highlighted the existence of a potassium switch in the kidney distal nephron. This switch seems to contribute importantly to the blood pressure-lowering effects of potassium intake. In recognition of these evolving data, the United States Food and Drug Administration is moving to permit potassium-containing salt substitutes in food manufacturing. Given that previous attempts to reduce salt consumption have not been successful, this new approach has a chance of improving health and ending the 'Salt Wars'.
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Affiliation(s)
- Robert Little
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- LeDucq Transatlantic Network of Excellence
| | - David H. Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon, USA
- Oregon Clinical & Translational Research Institute, Oregon Health & Science University, Portland, Oregon, USA
- LeDucq Transatlantic Network of Excellence
- VA Portland Health Care System, Portland, OR
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Mutchler SM, Whelan SCM, Marciszyn A, Chen J, Kleyman TR, Shi S. Role of paraoxonase 3 in regulating ENaC-mediated Na + transport in the distal nephron. J Physiol 2024; 602:737-757. [PMID: 38345534 PMCID: PMC10940207 DOI: 10.1113/jp285034] [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: 05/16/2023] [Accepted: 01/11/2024] [Indexed: 02/18/2024] Open
Abstract
Paraoxonase 3 (PON3) is expressed in the aldosterone-sensitive distal nephron, where filtered Na+ is reabsorbed mainly via the epithelial Na+ channel (ENaC) and Na+ -coupled co-transporters. We previously showed that PON3 negatively regulates ENaC through a chaperone mechanism. The present study aimed to determine the physiological role of PON3 in renal Na+ and K+ homeostasis. Pon3 knockout (KO) mice had higher amiloride-induced natriuresis and lower plasma [K+ ] at baseline. Single channel recordings in split-open tubules showed that the number of active channels per patch was significantly higher in KO mice, resulting in a higher channel activity in the absence of PON3. Although whole kidney abundance of ENaC subunits was not altered in Pon3 KOs, ENaC gamma subunit was more apically distributed within the connecting tubules and cortical collecting ducts of Pon3 KO kidneys. Additionally, small interfering RNA-mediated knockdown of PON3 in cultured mouse cortical collecting duct cells led to an increased surface abundance of ENaC gamma subunit. As a result of lower plasma [K+ ], sodium chloride co-transporter phosphorylation was enhanced in the KO kidneys, a phenotype that was corrected by a high K+ diet. Finally, PON3 expression was upregulated in mouse kidneys under dietary K+ restriction, potentially providing a mechanism to dampen ENaC activity and associated K+ secretion. Taken together, our results show that PON3 has a role in renal Na+ and K+ homeostasis through regulating ENaC functional expression in the distal nephron. KEY POINTS: Paraoxonase 3 (PON3) is expressed in the distal nephron of mouse kidneys and functions as a molecular chaperone to reduce epithelial Na+ channel (ENaC) expression and activity in heterologous expression systems. We examined the physiological role of PON3 in renal Na+ and K+ handling using a Pon3 knockout (KO) mouse model. At baseline, Pon3 KO mice had lower blood [K+ ], more functional ENaC in connecting tubules/cortical collecting ducts, higher amiloride-induced natriuresis, and enhanced sodium chloride co-transporter (NCC) phosphorylation. Upon challenge with a high K+ diet, Pon3 KO mice had normalized blood [K+ ] and -NCC phosphorylation but lower circulating aldosterone levels compared to their littermate controls. Kidney PON3 abundance was altered in mice under dietary K+ loading or K+ restriction, providing a potential mechanism for regulating ENaC functional expression and renal Na+ and K+ homeostasis in the distal nephron.
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Affiliation(s)
| | | | - Allison Marciszyn
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jingxin Chen
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Thomas R. Kleyman
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Shujie Shi
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
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7
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Drury ER, Wu J, Gigliotti JC, Le TH. Sex differences in blood pressure regulation and hypertension: renal, hemodynamic, and hormonal mechanisms. Physiol Rev 2024; 104:199-251. [PMID: 37477622 PMCID: PMC11281816 DOI: 10.1152/physrev.00041.2022] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 06/06/2023] [Accepted: 07/16/2023] [Indexed: 07/22/2023] Open
Abstract
The teleology of sex differences has been argued since at least as early as Aristotle's controversial Generation of Animals more than 300 years BC, which reflects the sex bias of the time to contemporary readers. Although the question "why are the sexes different" remains a topic of debate in the present day in metaphysics, the recent emphasis on sex comparison in research studies has led to the question "how are the sexes different" being addressed in health science through numerous observational studies in both health and disease susceptibility, including blood pressure regulation and hypertension. These efforts have resulted in better understanding of differences in males and females at the molecular level that partially explain their differences in vascular function and renal sodium handling and hence blood pressure and the consequential cardiovascular and kidney disease risks in hypertension. This review focuses on clinical studies comparing differences between men and women in blood pressure over the life span and response to dietary sodium and highlights experimental models investigating sexual dimorphism in the renin-angiotensin-aldosterone, vascular, sympathetic nervous, and immune systems, endothelin, the major renal sodium transporters/exchangers/channels, and the impact of sex hormones on these systems in blood pressure homeostasis. Understanding the mechanisms governing sex differences in blood pressure regulation could guide novel therapeutic approaches in a sex-specific manner to lower cardiovascular risks in hypertension and advance personalized medicine.
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Affiliation(s)
- Erika R Drury
- Division of Nephrology, Department of Medicine, University of Rochester Medical Center, Rochester, New York, United States
| | - Jing Wu
- Division of Nephrology, Department of Medicine, University of Rochester Medical Center, Rochester, New York, United States
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, United States
| | - Joseph C Gigliotti
- Department of Integrative Physiology and Pharmacology, Liberty University College of Osteopathic Medicine, Lynchburg, Virginia, United States
| | - Thu H Le
- Division of Nephrology, Department of Medicine, University of Rochester Medical Center, Rochester, New York, United States
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Grimm PR, Tatomir A, Rosenbaek LL, Kim BY, Li D, Delpire EJ, Fenton RA, Welling PA. Dietary potassium stimulates Ppp1Ca-Ppp1r1a dephosphorylation of kidney NaCl cotransporter and reduces blood pressure. J Clin Invest 2023; 133:e158498. [PMID: 37676724 PMCID: PMC10617769 DOI: 10.1172/jci158498] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 09/06/2023] [Indexed: 09/09/2023] Open
Abstract
Consumption of low dietary potassium, common with ultraprocessed foods, activates the thiazide-sensitive sodium chloride cotransporter (NCC) via the with no (K) lysine kinase/STE20/SPS1-related proline-alanine-rich protein kinase (WNK/SPAK) pathway to induce salt retention and elevate blood pressure (BP). However, it remains unclear how high-potassium "DASH-like" diets (dietary approaches to stop hypertension) inactivate the cotransporter and whether this decreases BP. A transcriptomics screen identified Ppp1Ca, encoding PP1A, as a potassium-upregulated gene, and its negative regulator Ppp1r1a, as a potassium-suppressed gene in the kidney. PP1A directly binds to and dephosphorylates NCC when extracellular potassium is elevated. Using mice genetically engineered to constitutively activate the NCC-regulatory kinase SPAK and thereby eliminate the effects of the WNK/SPAK kinase cascade, we confirmed that PP1A dephosphorylated NCC directly in a potassium-regulated manner. Prior adaptation to a high-potassium diet was required to maximally dephosphorylate NCC and lower BP in constitutively active SPAK mice, and this was associated with potassium-dependent suppression of Ppp1r1a and dephosphorylation of its cognate protein, inhibitory subunit 1 (I1). In conclusion, potassium-dependent activation of PP1A and inhibition of I1 drove NCC dephosphorylation, providing a mechanism to explain how high dietary K+ lowers BP. Shifting signaling of PP1A in favor of activation of WNK/SPAK may provide an improved therapeutic approach for treating salt-sensitive hypertension.
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Affiliation(s)
- P. Richard Grimm
- Department of Medicine (Nephrology), Johns Hopkins University School of Medicine Baltimore, Maryland, USA
- The LeDucq Potassium in Hypertension Research Network of Excellence is detailed in Supplemental Acknowledgments
| | - Anamaria Tatomir
- Department of Medicine (Nephrology), Johns Hopkins University School of Medicine Baltimore, Maryland, USA
| | - Lena L. Rosenbaek
- The LeDucq Potassium in Hypertension Research Network of Excellence is detailed in Supplemental Acknowledgments
- Department of Biomedicine, University of Aarhus, Aarhus, Denmark
| | - Bo Young Kim
- Department of Medicine (Nephrology), Johns Hopkins University School of Medicine Baltimore, Maryland, USA
- The LeDucq Potassium in Hypertension Research Network of Excellence is detailed in Supplemental Acknowledgments
| | - Dimin Li
- Department of Medicine (Nephrology), Johns Hopkins University School of Medicine Baltimore, Maryland, USA
| | - Eric J. Delpire
- The LeDucq Potassium in Hypertension Research Network of Excellence is detailed in Supplemental Acknowledgments
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennssee, USA
| | - Robert A. Fenton
- The LeDucq Potassium in Hypertension Research Network of Excellence is detailed in Supplemental Acknowledgments
- Department of Biomedicine, University of Aarhus, Aarhus, Denmark
| | - Paul A. Welling
- Department of Medicine (Nephrology), Johns Hopkins University School of Medicine Baltimore, Maryland, USA
- The LeDucq Potassium in Hypertension Research Network of Excellence is detailed in Supplemental Acknowledgments
- Department of Physiology, Johns Hopkins University School of Medicine Baltimore, Maryland, USA
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9
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Little R, Murali SK, Poulsen SB, Grimm PR, Assmus A, Cheng L, Ivy JR, Hoorn EJ, Matchkov V, Welling PA, Fenton RA. Dissociation of sodium-chloride cotransporter expression and blood pressure during chronic high dietary potassium supplementation. JCI Insight 2023; 8:156437. [PMID: 36719746 PMCID: PMC10077486 DOI: 10.1172/jci.insight.156437] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 01/25/2023] [Indexed: 02/01/2023] Open
Abstract
Dietary potassium (K+) supplementation is associated with a lowering effect in blood pressure (BP), but not all studies agree. Here, we examined the effects of short- and long-term K+ supplementation on BP in mice, whether differences depend on the accompanying anion or the sodium (Na+) intake and molecular alterations in the kidney that may underlie BP changes. Relative to the control diet, BP was higher in mice fed a high NaCl (1.57% Na+) diet for 7 weeks or fed a K+-free diet for 2 weeks. BP was highest on a K+-free/high NaCl diet. Commensurate with increased abundance and phosphorylation of the thiazide sensitive sodium-chloride-cotransporter (NCC) on the K+-free/high NaCl diet, BP returned to normal with thiazides. Three weeks of a high K+ diet (5% K+) increased BP (predominantly during the night) independently of dietary Na+ or anion intake. Conversely, 4 days of KCl feeding reduced BP. Both feeding periods resulted in lower NCC levels but in increased levels of cleaved (active) α and γ subunits of the epithelial Na+ channel ENaC. The elevated BP after chronic K+ feeding was reduced by amiloride but not thiazide. Our results suggest that dietary K+ has an optimal threshold where it may be most effective for cardiovascular health.
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Affiliation(s)
- Robert Little
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Søren B Poulsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Paul R Grimm
- Departments of Medicine, Nephrology and Physiology, Johns Hopkins School of Medicine, Baltimore, USA
| | - Adrienne Assmus
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Lei Cheng
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Jessica R Ivy
- University/BHF Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Ewout J Hoorn
- Department of Internal Medicine, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | | | - Paul A Welling
- Departments of Medicine, Nephrology and Physiology, Johns Hopkins School of Medicine, Baltimore, USA
| | - Robert A Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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10
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Van Beusecum JP, Rianto F, Teakell J, Kon V, Sparks MA, Hoorn EJ, Kirabo A, Ramkumar N. Novel Concepts in Nephron Sodium Transport: A Physiological and Clinical Perspective. ADVANCES IN KIDNEY DISEASE AND HEALTH 2023; 30:124-136. [PMID: 36868728 DOI: 10.1053/j.akdh.2022.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 12/15/2022] [Accepted: 12/15/2022] [Indexed: 04/13/2023]
Abstract
The kidneys play a critical role in maintaining total body sodium (Na+) balance across a wide range of dietary intake, accomplished by a concerted effort involving multiple Na+ transporters along the nephron. Furthermore, nephron Na+ reabsorption and urinary Na+ excretion are closely linked to renal blood flow and glomerular filtration such that perturbations in either of them can modify Na+ transport along the nephron, ultimately resulting in hypertension and other Na+-retentive states. In this article, we provide a brief physiological overview of nephron Na+ transport and illustrate clinical syndromes and therapeutic agents that affect Na+ transporter function. We highlight recent advances in kidney Na+ transport, particularly the role of immune cells, lymphatics, and interstitial Na+ in regulating Na+ reabsorption, the emergence of potassium (K+) as a regulator of Na+ transport, and the evolution of the nephron to modulate Na+ transport.
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Affiliation(s)
- Justin P Van Beusecum
- Ralph H. Johnson VA Medical Center, Charleston, SC; Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, SC
| | - Fitra Rianto
- Division of Nephrology, Department of Medicine, Duke University School of Medicine and Renal Section, Durham VA Health Care System Durham, Durham, NC
| | - Jade Teakell
- Division of Renal Diseases and Hypertension, Department of Medicine, McGovern Medical School, University of Texas Health Science Center, Houston, TX
| | - Valentina Kon
- Division of Nephrology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN
| | - Matthew A Sparks
- Division of Nephrology, Department of Medicine, Duke University School of Medicine and Renal Section, Durham VA Health Care System Durham, Durham, NC
| | - Ewout J Hoorn
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Annet Kirabo
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Nirupama Ramkumar
- Division of Nephrology and Hypertension, Department of Medicine, University of Utah Health, Salt Lake City, UT.
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11
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Abstract
The with no lysine (K) (WNK) kinases are an evolutionarily ancient group of kinases with atypical placement of the catalytic lysine and diverse physiological roles. Recent studies have shown that WNKs are directly regulated by chloride, potassium, and osmotic pressure. Here, we review the discovery of WNKs as chloride-sensitive kinases and discuss physiological contexts in which chloride regulation of WNKs has been demonstrated. These include the kidney, pancreatic duct, neurons, and inflammatory cells. We discuss the interdependent relationship of osmotic pressure and intracellular chloride in cell volume regulation. We review the recent demonstration of potassium regulation of WNKs and speculate on possible physiological roles. Finally, structural and mechanistic aspects of intracellular ion and osmotic pressure regulation of WNKs are discussed.
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Affiliation(s)
- Elizabeth J Goldsmith
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Aylin R Rodan
- Molecular Medicine Program, University of Utah, Salt Lake City, Utah, USA; .,Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.,Department of Human Genetics, University of Utah, Salt Lake City, Utah, USA.,Medical Service, Veterans Affairs Salt Lake City Healthcare System, Salt Lake City, Utah, USA
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12
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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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13
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Rosenbaek LL, Petrillo F, van Bemmelen MX, Staub O, Murali SK, Fenton RA. The E3 ubiquitin-protein ligase Nedd4-2 regulates the sodium chloride cotransporter NCC but is not required for a potassium-induced reduction of NCC expression. Front Physiol 2022; 13:971251. [PMID: 36160843 PMCID: PMC9490057 DOI: 10.3389/fphys.2022.971251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 08/18/2022] [Indexed: 11/21/2022] Open
Abstract
Na+ and K+ balance is influenced by the activity of the sodium chloride cotransporter NCC in the distal convoluted tubule. NCC activity and abundance are reduced by high extracellular K+. The E3 ubiquitin ligase neural precursor cell expressed developmentally downregulated 4–2 (Nedd4-2) has been proposed as a modulator of NCC abundance. Here, we examined the functional role of Nedd4-2 on NCC regulation and whether Nedd4-2 is important for the effects of high extracellular K+ on NCC. Total and plasma membrane levels of ubiquitylated NCC were lower in NCC-expressing MDCKI cells after Nedd4-2 deletion. NCC and phosphorylated NCC (pT58-NCC) levels were higher after Nedd4-2 deletion, and NCC levels on the plasma membrane were elevated. No significant changes were seen after Nedd4-2 knockdown in the levels of SPAK and phosphorylated SPAK (pS373-SPAK), the major NCC regulatory kinase. Nedd4-2 deficiency had no effect on the internalization rate of NCC from the plasma membrane, but NCC protein half-life was increased. In ex vivo experiments with kidney tubule suspensions from Nedd4-2 knockout (KO) mice, high K+ reduced total and pT58-NCC regardless of genotype. We conclude that Nedd4-2 is involved in ubiquitylation of NCC and modulating its plasma membrane levels and degradation. However, Nedd4-2 does not appear to be important for K+ induced reductions in NCC abundance.
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Affiliation(s)
- Lena L. Rosenbaek
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Leducq Foundation Potassium in Hypertension International Network, Massachusetts, United States
| | | | - Miguel X. van Bemmelen
- Leducq Foundation Potassium in Hypertension International Network, Massachusetts, United States
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Olivier Staub
- Leducq Foundation Potassium in Hypertension International Network, Massachusetts, United States
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Sathish K. Murali
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Leducq Foundation Potassium in Hypertension International Network, Massachusetts, United States
- Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Robert A. Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Leducq Foundation Potassium in Hypertension International Network, Massachusetts, United States
- *Correspondence: Robert A. Fenton,
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14
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Palmer LG. Directing two-way traffic in the kidney: A tale of two ions. J Gen Physiol 2022; 154:213433. [PMID: 36048011 PMCID: PMC9437110 DOI: 10.1085/jgp.202213179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The kidneys regulate levels of Na+ and K+ in the body by varying urinary excretion of the electrolytes. Since transport of each of the two ions can affect the other, controlling both at the same time is a complex task. The kidneys meet this challenge in two ways. Some tubular segments change the coupling between Na+ and K+ transport. In addition, transport of Na+ can shift between segments where it is coupled to K+ reabsorption and segments where it is coupled to K+ secretion. This permits the kidney to maintain electrolyte balance with large variations in dietary intake.
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Affiliation(s)
- Lawrence G. Palmer
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, NY,Correspondence to Lawrence G. Palmer:
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15
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Role of inwardly rectifying K+ channel 5.1 (Kir5.1) in the regulation of renal membrane transport. Curr Opin Nephrol Hypertens 2022; 31:479-485. [PMID: 35894283 DOI: 10.1097/mnh.0000000000000817] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Kir5.1 interacts with Kir4.2 in proximal tubule and with Kir4.1 in distal convoluted tubule (DCT), connecting tubule (CNT) and cortical collecting duct (CCD) to form basolateral-K+-channels. Kir4.2/Kir5.1 and Kir4.1/Kir5.1 play an important role in regulating Na+/HCO3--transport of the proximal tubule and Na+/K+ -transport in the DCT/CNT/CCD. The main focus of this review is to provide an overview of the recent development in the field regarding the role of Kir5.1 regulating renal electrolyte transport in the proximal tubule and DCT. RECENT FINDINGS Loss-of-function-mutations of KCNJ16 cause a new form of tubulopathy, characterized by hypokalaemia, Na+-wasting, acid-base-imbalance and metabolic-acidosis. Abnormal bicarbonate transport induced by loss-of-function of KCNJ16-mutants is recapitulated in Kir4.2-knockout-(Kir4.2 KO) mice. Deletion of Kir5.1 also abolishes the effect of dietary Na+ and K+-intakes on the basolateral membrane voltage and NCC expression/activity. Long-term high-salt intake or high-K+-intake causes hyperkalaemic in Kir5.1-deficient mice. SUMMARY Kir4.2/Kir5.1 activity in the proximal tubule plays a key role in regulating Na+, K+ and bicarbonate-transport through regulating electrogenic-Na+-bicarbonate-cotransporter-(NBCe1) and type 3-Na+/H+-exchanger-(NHE3). Kir4.1/Kir5.1 activity of the DCT plays a critical role in mediating the effect of dietary-K+ and Na+-intakes on NCC activity/expression. As NCC determines the Na+ delivery rate to the aldosterone-sensitive distal nephron (ASDN), defective regulation of NCC during high-salt and high-K+ compromises renal K+ excretion and K+ homeostasis.
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16
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Wu A, Wolley MJ, Matthews A, Cowley D, Welling PA, Fenton RA, Stowasser M. In Primary Aldosteronism Acute Potassium Chloride Supplementation Suppresses Abundance and Phosphorylation of the Sodium-Chloride Cotransporter. KIDNEY360 2022; 3:1909-1923. [PMID: 36514401 PMCID: PMC9717638 DOI: 10.34067/kid.0003632022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 08/25/2022] [Indexed: 01/12/2023]
Abstract
Background Elevated abundance of sodium-chloride cotransporter (NCC) and phosphorylated NCC (pNCC) are potential markers of primary aldosteronism (PA), but these effects may be driven by hypokalemia. Methods We measured plasma potassium in patients with PA. If potassium was <4.0 mmol/L, patients were given sufficient oral potassium chloride (KCl) over 24 hours to achieve as close to 4.0 mmol/L as possible. Clinical chemistries were assessed, and urinary extracellular vesicles (uEVs) were examined to investigate effects on NCC. Results Among 21 patients with PA who received a median total dose of 6.0 g (2.4-16.8 g) of KCl, increases were observed in plasma potassium (from 3.4 to 4.0 mmol/L; P<0.001), aldosterone (from 305 to 558 pmol/L; P=0.01), and renin (from 1.2 to 2.5 mIU/L; P<0.001), whereas decreases were detected in uEV levels of NCC (median fold change(post/basal) [FC]=0.71 [0.09-1.99]; P=0.02), pT60-NCC (FC=0.84 [0.06-1.66]; P=0.05), and pT55/60-NCC (FC=0.67 [0.08-2.42]; P=0.02). By contrast, in 10 patients with PA who did not receive KCl, there were no apparent changes in plasma potassium, NCC abundance, and phosphorylation status, but increases were observed in plasma aldosterone (from 178 to 418 pmol/L; P=0.006) and renin (from 2.0 to 3.0 mU/L; P=0.009). Plasma potassium correlated inversely with uEV levels of NCC (R 2=0.11; P=0.01), pT60-NCC (R 2=0.11; P=0.01), and pT55/60-NCC (R 2=0.11; P=0.01). Conclusions Acute oral KCl loading replenished plasma potassium in patients with PA and suppressed NCC abundance and phosphorylation, despite a significant rise in plasma aldosterone. This supports the view that potassium supplementation in humans with PA overrides the aldosterone stimulatory effect on NCC. The increased plasma aldosterone in patients with PA without KCl supplementation may be due to aldosterone response to posture challenge.
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Affiliation(s)
- Aihua Wu
- Endocrine Hypertension Research Centre, The University of Queensland Diamantina Institute, Greenslopes and Princess Alexandra Hospitals, Brisbane, Australia
| | - Martin J. Wolley
- Endocrine Hypertension Research Centre, The University of Queensland Diamantina Institute, Greenslopes and Princess Alexandra Hospitals, Brisbane, Australia,Department of Nephrology, Royal Brisbane and Women’s Hospital, Brisbane, Australia
| | - Alexandra Matthews
- Endocrine Hypertension Research Centre, The University of Queensland Diamantina Institute, Greenslopes and Princess Alexandra Hospitals, Brisbane, Australia
| | - Diane Cowley
- Endocrine Hypertension Research Centre, The University of Queensland Diamantina Institute, Greenslopes and Princess Alexandra Hospitals, Brisbane, Australia
| | - Paul A. Welling
- Department of Medicine and Physiology, Johns Hopkins University, Baltimore, Maryland
| | | | - Michael Stowasser
- Endocrine Hypertension Research Centre, The University of Queensland Diamantina Institute, Greenslopes and Princess Alexandra Hospitals, Brisbane, Australia
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17
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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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18
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McDonough AA, Fenton RA. Potassium homeostasis: sensors, mediators, and targets. Pflugers Arch 2022; 474:853-867. [PMID: 35727363 PMCID: PMC10163916 DOI: 10.1007/s00424-022-02718-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 06/08/2022] [Accepted: 06/12/2022] [Indexed: 12/16/2022]
Abstract
Transmembrane potassium (K) gradients are key determinants of membrane potential that can modulate action potentials, control muscle contractility, and influence ion channel and transporter activity. Daily K intake is normally equal to the amount of K in the entire extracellular fluid (ECF) creating a critical challenge - how to maintain ECF [K] and membrane potential in a narrow range during feast and famine. Adaptations to maintain ECF [K] include sensing the K intake, sensing ECF [K] vs. desired set-point and activating mediators that regulate K distribution between ECF and ICF, and regulate renal K excretion. In this focused review, we discuss the basis of these adaptions, including (1) potential mechanisms for rapid feedforward signaling to kidney and muscle after a meal (before a rise in ECF [K]), (2) how skeletal muscles sense and respond to changes in ECF [K], (3) effects of K on aldosterone biosynthesis, and (4) how the kidney responds to changes in ECF [K] to modify K excretion. The concepts of sexual dimorphisms in renal K handling adaptation are introduced, and the molecular mechanisms that can account for the benefits of a K-rich diet to maintain cardiovascular health are discussed. Although the big picture of K homeostasis is becoming more clear, we also highlight significant pieces of the puzzle that remain to be solved, including knowledge gaps in our understanding of initiating signals, sensors and their connection to homeostatic adjustments of ECF [K].
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Affiliation(s)
- Alicia A McDonough
- Department of Physiology and Neuroscience, University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
| | - Robert A Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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19
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Svendsen SL, Kornvig S, Berg P, Jensen IS, Araujo IBBA, Larsen CK, Leipziger J, Sørensen MV. Dietary K + acts as a genuine diuretic. Acta Physiol (Oxf) 2022; 234:e13762. [PMID: 34984847 DOI: 10.1111/apha.13762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 11/29/2021] [Accepted: 01/01/2022] [Indexed: 12/11/2022]
Abstract
K+ balance in mammals relies on regulated renal K+ excretion matching unregulated fluctuating K+ intake. Upon a K+ rich meal, rapid and powerful K+ excretion is needed. Renal K+ secretion is stimulated by the increased tubular flow. We speculated that high K+ intake acutely increases urinary flow to stimulate K+ excretion. METHODS Mice were K+ challenged through diets or gavage. Post K+ loading urinary output, osmolarity, [K+ ]u , [Na+ ]u , plasma osmolarity, [copeptin]p , [K+ ]p , and [Na+ ]p were measured. To locate the mechanism of K+ -induced diuresis in the glomerular/tubular system we measured creatinine excretion and assessed functional transport in isolated perfused TALs and CDs during an acute [K+ ]bl switch from 3.6 to 6.5 mM. Molecular adaptations of transport proteins involved in water reabsorption were investigated by immunoblotting. RESULTS (1) Mice switched from a 1% to 2% K+ diet increased diuresis within 12 hours and reciprocally reduced diuresis when switched from 1% to 0.01% K+ diet. (2) A single K+ gavage load, corresponding to 25%-50% of daily K+ intake, induced 100% increase in diuresis within 30 minutes. This occurred despite augmented plasma osmolarity and AVP synthesis. (3) K+ gavage did not change GFR. (4) In isolated perfused TALs, shifting [K+ ]bl from 3.6 to 6.5 mM did not affect AVP-induced NaCl transport. (5) In sharp contrast, in isolated perfused CDs, shifting [K+ ]bl from 3.6 to 6.5 mM markedly reduced CD AVP sensitivity, ie inhibited water absorption. CONCLUSION Dietary K+ loading induces a rapidly on-setting diuresis. The mechanism of K+ -induced diuresis involves desensitization of the CD to AVP.
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Affiliation(s)
- Samuel L. Svendsen
- Department of Biomedicine, Physiology, Health Aarhus University Aarhus C Denmark
| | - Simon Kornvig
- Department of Biomedicine, Physiology, Health Aarhus University Aarhus C Denmark
| | - Peder Berg
- Department of Biomedicine, Physiology, Health Aarhus University Aarhus C Denmark
| | - Iben S. Jensen
- Department of Biomedicine, Physiology, Health Aarhus University Aarhus C Denmark
| | | | - Casper K. Larsen
- Department of Biomedicine, Physiology, Health Aarhus University Aarhus C Denmark
| | - Jens Leipziger
- Department of Biomedicine, Physiology, Health Aarhus University Aarhus C Denmark
| | - Mads V. Sørensen
- Department of Biomedicine, Physiology, Health Aarhus University Aarhus C Denmark
- Aarhus Institute for Advanced Studies (AIAS) Aarhus University Aarhus C Denmark
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20
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Weinstein AM. A mathematical model of the rat kidney. IV. Whole kidney response to hyperkalemia. Am J Physiol Renal Physiol 2022; 322:F225-F244. [PMID: 35001663 PMCID: PMC8836735 DOI: 10.1152/ajprenal.00413.2021] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The renal response to acute hyperkalemia is mediated by increased K+ secretion within the connecting tubule (CNT), flux that is modulated by tubular effects (e.g., aldosterone) in conjunction with increased luminal flow. There is ample evidence that peritubular K+ blunts Na+ reabsorption in the proximal tubule, thick ascending Henle limb, and distal convoluted tubule (DCT). Although any such reduction may augment CNT delivery, the relative contribution of each is uncertain. The kidney model of this laboratory was recently advanced with representation of the cortical labyrinth and medullary ray. Model tubules capture the impact of hyperkalemia to blunt Na+ reabsorption within each upstream segment. However, this forces the question of the extent to which increased Na+ delivery is transmitted past the macula densa and its tubuloglomerular feedback (TGF) signal. Beyond increasing macula densa Na+ delivery, peritubular K+ is predicted to raise cytosolic Cl- and depolarize macula densa cells, which may also activate TGF. Thus, although the upstream reduction in Na+ transport may be larger, it appears that the DCT effect is critical to increasing CNT delivery. Beyond the flow effect, hyperkalemia reduces ammoniagenesis and reduced ammoniagenesis enhances K+ excretion. What this model provides is a possible mechanism. When cortical [Formula: see text] is taken up via peritubular Na+-K+([Formula: see text])-ATPase, it acidifies principal cells. Consequently, reduced ammoniagenesis increases principal cell pH, thereby increasing conductance of both the epithelial Na+ channel and renal outer medullary K+ channel, enhancing K+ excretion. In this model, the effect of aldosterone on principal cells, diminished DCT Na+ reabsorption, and reduced ammoniagenesis all provide relatively equal and additive contributions to renal K+ excretion.NEW & NOTEWORTHY Hyperkalemia blunts Na+ reabsorption along the nephron, and increased CNT Na+ delivery facilitates K+ secretion. The model suggests that tubuloglomerular feedback limits transmission of proximal effects past the macula densa, so that it is DCT transport that is critical. Hyperkalemia also reduces PCT ammoniagenesis, which enhances K+ excretion. The model suggests a mechanism, namely, that reduced cortical ammonia impacts CNT transport by raising cell pH and thus increasing both ENaC and ROMK conductance.
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Affiliation(s)
- Alan M. Weinstein
- 1Department of Physiology and Biophysics, Weill Medical College of Cornell University, New York City, New York,2Department of Medicine, Weill Medical College of Cornell University, New York City, New York
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21
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Zapf AM, Grimm PR, Al-Qusairi L, Delpire E, Welling PA. Low Salt Delivery Triggers Autocrine Release of Prostaglandin E2 From the Aldosterone-Sensitive Distal Nephron in Familial Hyperkalemic Hypertension Mice. Front Physiol 2022; 12:787323. [PMID: 35069250 PMCID: PMC8770744 DOI: 10.3389/fphys.2021.787323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/19/2021] [Indexed: 11/13/2022] Open
Abstract
Aberrant activation of with-no-lysine kinase (WNK)-STE20/SPS1-related proline-alanine-rich protein kinase (SPAK) kinase signaling in the distal convoluted tubule (DCT) causes unbridled activation of the thiazide-sensitive sodium chloride cotransporter (NCC), leading to familial hyperkalemic hypertension (FHHt) in humans. Studies in FHHt mice engineered to constitutively activate SPAK specifically in the DCT (CA-SPAK mice) revealed maladaptive remodeling of the aldosterone sensitive distal nephron (ASDN), characterized by decrease in the potassium excretory channel, renal outer medullary potassium (ROMK), and epithelial sodium channel (ENaC), that contributes to the hyperkalemia. The mechanisms by which NCC activation in DCT promotes remodeling of connecting tubule (CNT) are unknown, but paracrine communication and reduced salt delivery to the ASDN have been suspected. Here, we explore the involvement of prostaglandin E2 (PGE2). We found that PGE2 and the terminal PGE2 synthase, mPGES1, are increased in kidney cortex of CA-SPAK mice, compared to control or SPAK KO mice. Hydrochlorothiazide (HCTZ) reduced PGE2 to control levels, indicating increased PGE2 synthesis is dependent on increased NCC activity. Immunolocalization studies revealed mPGES1 is selectively increased in the CNT of CA-SPAK mice, implicating low salt-delivery to ASDN as the trigger. Salt titration studies in an in vitro ASDN cell model, mouse CCD cell (mCCD-CL1), confirmed PGE2 synthesis is activated by low salt, and revealed that response is paralleled by induction of mPGES1 gene expression. Finally, inhibition of the PGE2 receptor, EP1, in CA-SPAK mice partially restored potassium homeostasis as it partially rescued ROMK protein abundance, but not ENaC. Together, these data indicate low sodium delivery to the ASDN activates PGE2 synthesis and this inhibits ROMK through autocrine activation of the EP1 receptor. These findings provide new insights into the mechanism by which activation of sodium transport in the DCT causes remodeling of the ASDN.
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Affiliation(s)
- Ava M Zapf
- Molecular Medicine, Graduate Program in Life Sciences, University of Maryland Medical School, Baltimore, MD, United States
| | - Paul R Grimm
- Department of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Lama Al-Qusairi
- Department of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University Medical School, Nashville, TN, United States
| | - Paul A Welling
- Department of Medicine, Johns Hopkins University, Baltimore, MD, United States.,Department of Physiology, Johns Hopkins University, Baltimore, MD, United States
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22
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Polidoro JZ, Luchi WM, Seguro AC, Malnic G, Girardi ACC. Paracrine and endocrine regulation of renal potassium secretion. Am J Physiol Renal Physiol 2022; 322:F360-F377. [DOI: 10.1152/ajprenal.00251.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The seminal studies conducted by Giebisch and colleagues in the 1960s paved the way for understanding the renal mechanisms involved in K+ homeostasis. It was demonstrated that differential handling of K+ in the distal segments of the nephron is crucial for proper K+ balance. Although aldosterone had been classically ascribed as the major ion transport regulator in the distal nephron, thereby contributing to K+ homeostasis, it became clear that aldosterone per se could not explain the kidney's ability to modulate kaliuresis in both acute and chronic settings. The existence of alternative kaliuretic and antikaliuretic mechanisms was suggested by physiological studies in the 1980s but only gained form and shape with the advent of molecular biology. It is now established that the kidneys recruit several endocrine and paracrine mechanisms for adequate kaliuretic response. These mechanisms include the direct effects of peritubular K+, a gut-kidney regulatory axis sensing dietary K+ levels, the kidney secretion of kallikrein during postprandial periods, the upregulation of angiotensin II receptors in the distal nephron during chronic changes in the K+ diet, and the local increase of prostaglandins by low K+ diet. This review discusses recent advances in the understanding of endocrine and paracrine mechanisms underlying the modulation of K+ secretion and how these mechanisms impact kaliuresis and K+ balance. We also highlight important unknowns about the regulation of renal K+ excretion under physiological circumstances.
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Affiliation(s)
- Juliano Z. Polidoro
- Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
| | - Weverton Machado Luchi
- Department of Internal Medicine, Federal University of Espírito Santo (UFES), Vitória, Espírito Santo, Brazil
| | - Antonio Carlos Seguro
- Department of Nephrology (LIM 12), University of São Paulo Medical School, São Paulo, São Paulo, Brazil
| | - Gerhard Malnic
- Department of Physiology and Biophysics, University of São Paulo Medical School, São Paulo, Brazil
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23
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Preston RA, Afshartous D, Caizapanta EV, Materson BJ, Rodco R, Alonso E, Alonso AB. Characterization of Potassium-Induced Natriuresis in Hypertensive Postmenopausal Women During Both Low and High Sodium Intake. Hypertension 2022; 79:813-826. [PMID: 35045721 DOI: 10.1161/hypertensionaha.121.18392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Potassium-induced natriuresis may contribute to the beneficial effects of potassium on blood pressure but has not been well-characterized in human postmenopausal hypertension. We determined the time course and magnitude of potassium-induced natriuresis and kaliuresis compared with hydrochlorothiazide in 19 hypertensive Hispanic postmenopausal women. We also determined the modulating effects of sodium intake, sodium-sensitivity, and activity of the thiazide-sensitive NCC (sodium-chloride cotransporter). METHODS Sixteen-day inpatient confinement: 8 days low sodium followed by 8 days high sodium intake. During both periods, we determined sodium and potassium excretion following 35 mmol oral KCl versus 50 mg hydrochlorothiazide. We determined sodium-sensitivity as change in 24-hour systolic pressure from low to high sodium. We determined NCC activity by standard thiazide-sensitivity test. RESULTS Steady-state sodium intake was the key determinant of potassium-induced natriuresis. During low sodium intake, sodium excretion was low and did not increase following 35 mmol KCl indicating continued sodium conservation. Conversely, during high sodium intake, sodium excretion increased sharply following 35 mmol KCl to ≈37% of that produced by hydrochlorothiazide. Under both low and high sodium intake, 35 mmol potassium was mostly excreted within 5 hours, accompanied by a sodium load reflecting the steady-state sodium intake, consistent with independent regulation of sodium/potassium excretion in the human distal nephron. CONCLUSIONS Potassium-induced natriuresis was not greater in sodium-sensitive versus sodium-resistant hypertensives or hypertensives with higher versus lower basal NCC activity. We studied an acute KCl challenge. It remains to further characterize potassium-induced natriuresis during chronic potassium increase and when potassium is administered a complex potassium-containing meal.
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Affiliation(s)
- Richard A Preston
- Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine University of Miami. Clinical Pharmacology Research Unit, Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine, University of Miami, FL. (R.A.P., D.A., E.V.C., B.J.M., R.R., E.A., A.B.A.).,University of Miami Clinical and Translational Science Institutes (CTSI), Miller School of Medicine, University of Miami, FL. (R.A.P.).,The Peggy and Harold Katz Family Drug Discovery center, Miller School of Medicine, University of Miami, FL. (R.A.P.)
| | - David Afshartous
- Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine University of Miami. Clinical Pharmacology Research Unit, Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine, University of Miami, FL. (R.A.P., D.A., E.V.C., B.J.M., R.R., E.A., A.B.A.)
| | - Evelyn V Caizapanta
- Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine University of Miami. Clinical Pharmacology Research Unit, Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine, University of Miami, FL. (R.A.P., D.A., E.V.C., B.J.M., R.R., E.A., A.B.A.)
| | - Barry J Materson
- Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine University of Miami. Clinical Pharmacology Research Unit, Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine, University of Miami, FL. (R.A.P., D.A., E.V.C., B.J.M., R.R., E.A., A.B.A.)
| | - Rolando Rodco
- Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine University of Miami. Clinical Pharmacology Research Unit, Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine, University of Miami, FL. (R.A.P., D.A., E.V.C., B.J.M., R.R., E.A., A.B.A.)
| | - Eileen Alonso
- Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine University of Miami. Clinical Pharmacology Research Unit, Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine, University of Miami, FL. (R.A.P., D.A., E.V.C., B.J.M., R.R., E.A., A.B.A.)
| | - Alberto B Alonso
- Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine University of Miami. Clinical Pharmacology Research Unit, Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine, University of Miami, FL. (R.A.P., D.A., E.V.C., B.J.M., R.R., E.A., A.B.A.)
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24
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Potassium Effects on NCC Are Attenuated during Inhibition of Cullin E3-Ubiquitin Ligases. Cells 2021; 11:cells11010095. [PMID: 35011657 PMCID: PMC8750104 DOI: 10.3390/cells11010095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 01/02/2023] Open
Abstract
The thiazide-sensitive sodium chloride cotransporter (NCC) plays a vital role in maintaining sodium (Na+) and potassium (K+) homeostasis. NCC activity is modulated by with-no-lysine kinases 1 and 4 (WNK1 and WNK4), the abundance of which is controlled by the RING-type E3 ligase Cullin 3 (Cul3) and its substrate adapter Kelch-like protein 3. Dietary K+ intake has an inverse correlation with NCC activity, but the mechanism underlying this phenomenon remains to be fully elucidated. Here, we investigated the involvement of other members of the cullin family in mediating K+ effects on NCC phosphorylation (active form) and abundance. In kidneys from mice fed diets varying in K+ content, there were negative correlations between NCC (phosphorylated and total) and active (neddylated) forms of cullins (Cul1, 3, 4, and 5). High dietary K+ effects on phosphorylated NCC were attenuated in Cul3 mutant mice (CUL3-Het/Δ9). Short-term (30 min) and long-term (24 h) alterations in the extracellular K+ concentration did not affect cullin neddylation levels in ex vivo renal tubules. In the short term, the ability of high extracellular K+ to decrease NCC phosphorylation was preserved in the presence of MLN4924 (pan-cullin inhibitor), but the response to low extracellular K+ was absent. In the long term, MLN4924 attenuated the effects of high extracellular K+ on NCC phosphorylation, and responses to low extracellular K+ were absent. Our data suggest that in addition to Cul3, other cullins are involved in mediating the effects of K+ on NCC phosphorylation and abundance.
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25
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Castañeda-Bueno M, Ellison DH, Gamba G. Molecular mechanisms for the modulation of blood pressure and potassium homeostasis by the distal convoluted tubule. EMBO Mol Med 2021; 14:e14273. [PMID: 34927382 PMCID: PMC8819348 DOI: 10.15252/emmm.202114273] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 11/17/2021] [Accepted: 12/01/2021] [Indexed: 12/15/2022] Open
Abstract
Epidemiological and clinical observations have shown that potassium ingestion is inversely correlated with arterial hypertension prevalence and cardiovascular mortality. The higher the dietary potassium, the lower the blood pressure and mortality. This phenomenon is explained, at least in part, by the interaction between salt reabsorption in the distal convoluted tubule (DCT) and potassium secretion in the connecting tubule/collecting duct of the mammalian nephron: In order to achieve adequate K+ secretion levels under certain conditions, salt reabsorption in the DCT must be reduced. Because salt handling by the kidney constitutes the basis for the long‐term regulation of blood pressure, losing salt prevents hypertension. Here, we discuss how the study of inherited diseases in which salt reabsorption in the DCT is affected has revealed the molecular players, including membrane transporters and channels, kinases, and ubiquitin ligases that form the potassium sensing mechanism of the DCT and the processes through which the consequent adjustments in salt reabsorption are achieved.
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Affiliation(s)
- María Castañeda-Bueno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, OR, USA.,Oregon Clinical & Translational Research Institute, Oregon Health & Science University, Portland, OR, USA.,VA Portland Health Care System, Portland, OR, USA
| | - Gerardo Gamba
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico.,Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico
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26
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Moser S, Sugano Y, Wengi A, Fisi V, Lindtoft Rosenbaek L, Mariniello M, Loffing‐Cueni D, McCormick JA, Fenton RA, Loffing J. A five amino acids deletion in NKCC2 of C57BL/6 mice affects analysis of NKCC2 phosphorylation but does not impact kidney function. Acta Physiol (Oxf) 2021; 233:e13705. [PMID: 34114742 PMCID: PMC8384713 DOI: 10.1111/apha.13705] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 05/04/2021] [Accepted: 06/07/2021] [Indexed: 12/24/2022]
Abstract
Aim The phosphorylation level of the furosemide‐sensitive Na+‐K+‐2Cl− cotransporter (NKCC2) in the thick ascending limb (TAL) is used as a surrogate marker for NKCC2 activation and TAL function. However, in mice, analyses of NKCC2 phosphorylation with antibodies against phosphorylated threonines 96 and 101 (anti‐pT96/pT101) give inconsistent results. We aimed (a) to elucidate these inconsistencies and (b) to develop a phosphoform‐specific antibody that ensures reliable detection of NKCC2 phosphorylation in mice. Methods Genetic information, molecular biology, biochemical techniques and mouse phenotyping was used to study NKCC2 and kidney function in two commonly used mouse strains (ie 129Sv and in C57BL/6 mice). Moreover, a new phosphoform‐specific mouse NKCC2 antibody was developed and characterized. Results Amino acids sequence alignment revealed that C57BL/6 mice have a strain‐specific five amino acids deletion (ΔF97‐T101) in NKCC2 that diminishes the detection of NKCC2 phosphorylation with previously developed pT96/pT101 NKCC2 antibodies. Instead, the antibodies cross‐react with the phosphorylated thiazide‐sensitive NaCl cotransporter (NCC), which can obscure interpretation of results. Interestingly, the deletion in NKCC2 does not impact on kidney function and/or expression of renal ion transport proteins as indicated by the analysis of the F2 generation of crossbred 129Sv and C57BL/6 mice. A newly developed pT96 NKCC2 antibody detects pNKCC2 in both mouse strains and shows no cross‐reactivity with phosphorylated NCC. Conclusion Our work reveals a hitherto unappreciated, but essential, strain difference in the amino acids sequence of mouse NKCC2 that needs to be considered when analysing NKCC2 phosphorylation in mice. The new pNKCC2 antibody circumvents this technical caveat.
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Affiliation(s)
- Sandra Moser
- Institute of Anatomy University of Zurich Zurich Switzerland
| | - Yuya Sugano
- Institute of Anatomy University of Zurich Zurich Switzerland
| | - Agnieszka Wengi
- Institute of Anatomy University of Zurich Zurich Switzerland
| | - Viktoria Fisi
- Institute of Anatomy University of Zurich Zurich Switzerland
| | | | | | | | - James A. McCormick
- Division of Nephrology and Hypertension Oregon Health & Science University Portland OR USA
| | | | - Johannes Loffing
- Institute of Anatomy University of Zurich Zurich Switzerland
- Swiss National Centre for Competence in Research “Kidney control of homeostasis” Zurich Switzerland
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27
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Xu C, Chen Y, Wang F, Xie S, Yang T. Soluble (Pro)Renin Receptor as a Negative Regulator of NCC (Na +-Cl - Cotransporter) Activity. Hypertension 2021; 78:1027-1038. [PMID: 34495675 PMCID: PMC9212213 DOI: 10.1161/hypertensionaha.121.16981] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 06/02/2021] [Indexed: 12/15/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Chuanming Xu
- Internal Medicine, University of Utah and Veterans Affairs Medical Center, Salt Lake City, Utah, the United States
- Translational Medicine Centre, Jiangxi University of Chinese Medicine, Nanchang, Jiangxi, China
| | - Yanting Chen
- Internal Medicine, University of Utah and Veterans Affairs Medical Center, Salt Lake City, Utah, the United States
| | - Fei Wang
- Internal Medicine, University of Utah and Veterans Affairs Medical Center, Salt Lake City, Utah, the United States
| | - Shiying Xie
- Institute of Hypertension, Sun Yat-sen University School of Medicine, Guangzhou, China
| | - Tianxin Yang
- Internal Medicine, University of Utah and Veterans Affairs Medical Center, Salt Lake City, Utah, the United States
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28
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Nelson JW, McDonough AA, Xiang Z, Ralph DL, Robertson JA, Giani JF, Bernstein KE, Gurley SB. Local and downstream actions of proximal tubule angiotensin II signaling on Na + transporters in the mouse nephron. Am J Physiol Renal Physiol 2021; 321:F69-F81. [PMID: 34056928 DOI: 10.1152/ajprenal.00014.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The renal nephron consists of a series of distinct cell types that function in concert to maintain fluid and electrolyte balance and blood pressure. The renin-angiotensin system (RAS) is central to Na+ and volume balance. We aimed to determine how loss of angiotensin II signaling in the proximal tubule (PT), which reabsorbs the bulk of filtered Na+ and volume, impacts solute transport throughout the nephron. We hypothesized that PT renin-angiotensin system disruption would not only depress PT Na+ transporters but also impact downstream Na+ transporters. Using a mouse model in which the angiotensin type 1a receptor (AT1aR) is deleted specifically within the PT (AT1aR PTKO), we profiled the abundance of Na+ transporters, channels, and claudins along the nephron. Absence of PT AT1aR signaling was associated with lower abundance of PT transporters (Na+/H+ exchanger isoform 3, electrogenic Na+-bicarbonate cotransporter 1, and claudin 2) as well as lower abundance of downstream transporters (total and phosphorylated Na+-K+-2Cl- cotransporter, medullary Na+-K+-ATPase, phosphorylated NaCl cotransporter, and claudin 7) versus controls. However, transport activities of Na+-K+-2Cl- cotransporter and NaCl cotransporter (assessed with diuretics) were similar between groups in order to maintain electrolyte balance. Together, these results demonstrate the primary impact of angiotensin II regulation on Na+ reabsorption in the PT at baseline and the associated influence on downstream Na+ transporters, highlighting the ability of the nephron to integrate Na+ transport along the nephron to maintain homeostasis.NEW & NOTEWORTHY Our study defines a novel role for proximal tubule angiotensin receptors in regulating the abundance of Na+ transporters throughout the nephron, thereby contributing to the integrated control of fluid balance in vivo.
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Affiliation(s)
- Jonathan W Nelson
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Alicia A McDonough
- Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Zhidan Xiang
- Wake Forest University, Winston-Salem, North Carolina
| | - Donna L Ralph
- Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Joshua A Robertson
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Jorge F Giani
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California
| | - Kenneth E Bernstein
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California
| | - Susan B Gurley
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
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29
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Xiao Y, Duan XP, Zhang DD, Wang WH, Lin DH. Deletion of renal Nedd4-2 abolishes the effect of high K + intake on Kir4.1/Kir5.1 and NCC activity in the distal convoluted tubule. Am J Physiol Renal Physiol 2021; 321:F1-F11. [PMID: 34029145 DOI: 10.1152/ajprenal.00072.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
High-dietary K+ (HK) intake inhibits basolateral Kir4.1/Kir5.1 activity in the distal convoluted tubule (DCT), and HK-induced inhibition of Kir4.1/Kir5.1 is essential for HK-induced inhibition of NaCl cotransporter (NCC). Here, we examined whether neural precursor cell expressed developmentally downregulated 4-2 (Nedd4-2) deletion compromises the effect of HK on basolateral Kir4.1/Kir5.1 and NCC in the DCT. Single-channel recording and whole cell recording showed that neither HK decreased nor low-dietary K+ (LK) increased basolateral Kir4.1/Kir5.1 activity of the DCT in kidney tubule-specific Nedd4-2 knockout (Ks-Nedd4-2 KO) mice. In contrast, HK inhibited and LK increased Kir4.1/Kir5.1 activity in control mice [neural precursor cell expressed developmentally downregulated 4-like (Nedd4l)flox/flox]. Also, HK intake decreased the negativity of K+ current reversal potential in the DCT (depolarization) only in control mice but not in Ks-Nedd4-2 KO mice. Renal clearance experiments showed that HK intake decreased, whereas LK intake increased, hydrochlorothiazide-induced renal Na+ excretion only in control mice, but this effect was absent in Ks-Nedd4-2 KO mice. Western blot analysis also demonstrated that HK-induced inhibition of phosphorylated NCC (Thr53) and total NCC was observed only in control mice but not in Ks-Nedd4-2 KO mice. Furthermore, expression of all three subunits of the epithelial Na+ channel in Ks-Nedd4-2 KO mice on HK was higher than in control mice. Thus, plasma K+ concentrations were similar between Nedd4lflox/flox and Ks-Nedd4-2 KO mice on HK for 7 days despite high NCC expression. We conclude that Nedd4-2 plays a role in regulating HK-induced inhibition of Kir4.1/Kir5.1 and NCC in the DCT.NEW & NOTEWORTHY Basolateral Kir4.1/Kir5.1 in the distal convoluted tubule plays an important role as a "K+ sensor" in the regulation of renal K+ excretion after high K+ intake. We found that neural precursor cell expressed developmentally downregulated 4-2 (Nedd4-2) a role in mediating the effect of K+ diet on Kir4.1/Kir5.1 and NaCl cotransporter because high K+ intake failed to inhibit basolateral Kir4.1/Kir5.1 and NaCl cotransporter in kidney tubule-specific Nedd4-2 knockout mice.
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Affiliation(s)
- Yu Xiao
- Department of Physiology, Qiqihar Medical College, Heilongjiang, China.,Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Xin-Peng Duan
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dan-Dan Zhang
- Department of Pharmacology, 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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30
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Mukherjee A, Yang CL, McCormick JA, Martz K, Sharma A, Ellison DH. Roles of WNK4 and SPAK in K +-mediated dephosphorylation of the NaCl cotransporter. Am J Physiol Renal Physiol 2021; 320:F719-F733. [PMID: 33719576 PMCID: PMC8174808 DOI: 10.1152/ajprenal.00459.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 03/02/2021] [Accepted: 03/03/2021] [Indexed: 02/06/2023] Open
Abstract
Phosphorylation of the thiazide-sensitive NaCl cotransporter (NCC) in the distal convoluted tubule (DCT) is altered rapidly in response to changes in extracellular K+ concentration ([K+]). High extracellular [K+] is believed to activate specific phosphatases to dephosphorylate NCC, thereby reducing its activity. This process is defective in the human disease familial hyperkalemic hypertension, in which extracellular [K+] fails to dephosphorylate NCC, suggesting an interplay between NCC-activating and NCC-inactivating switches. Here, we explored the role of STE20/SPS1-related proline-alanine-rich protein kinase (SPAK) and intracellular Cl- concentration in the rapid effects of extracellular K+ on NCC phosphorylation. SPAK was found to be rapidly dephosphorylated in vitro in human embryonic kidney cells and ex vivo in kidney slices by high [K+]. Acute high-K+ challenge resulted in DCT1-specific SPAK dephosphorylation in vivo and dissolution of SPAK puncta. In line with the postulate of interplay between activating and inactivating switches, we found that the "on" switch, represented by with no lysine kinase 4 (WNK4)-SPAK, must be turned off for rapid NCC dephosphorylation by high [K+]. Longer-term WNK-SPAK-mediated stimulation, however, altered the sensitivity of the system, as it attenuated rapid NCC dephosphorylation due to acute K+ loading. Although blockade of protein phosphatase (PP)1 increased NCC phosphorylation at baseline, neither PP1 nor PP3, singly or in combination, was essential for NCC dephosphorylation. Overall, our data suggest that NCC phosphorylation is regulated by a dynamic equilibrium between activating kinases and inactivating phosphatases, with kinase inactivation playing a key role in the rapid NCC dephosphorylation by high extracellular K+.NEW & NOTEWORTHY Although a great deal is known about mechanisms by which thiazide-sensitive NaCl cotransporter is phosphorylated and activated, much less is known about dephosphorylation. Here, we show that rapid dephosphorylation by high K+ depends on the Cl- sensitivity of with no lysine kinase 4 and the rapid dephosphorylation of STE20/SPS1-related proline-alanine-rich protein kinase, primarily along the early distal convoluted tubule.
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Affiliation(s)
- Anindit Mukherjee
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Chao-Ling Yang
- 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
| | - Kevin Martz
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Avika Sharma
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
- Oregon Clinical and Translational Research Institute, Oregon Health and Science University, Portland, Oregon
- Veterans Affairs Portland Health Care System, Portland, Oregon
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31
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Ayuzawa N, Fujita T. The Mineralocorticoid Receptor in Salt-Sensitive Hypertension and Renal Injury. J Am Soc Nephrol 2021; 32:279-289. [PMID: 33397690 PMCID: PMC8054893 DOI: 10.1681/asn.2020071041] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Hypertension and its comorbidities pose a major public health problem associated with disease-associated factors related to a modern lifestyle, such high salt intake or obesity. Accumulating evidence has demonstrated that aldosterone and its receptor, the mineralocorticoid receptor (MR), have crucial roles in the development of salt-sensitive hypertension and coexisting cardiovascular and renal injuries. Accordingly, clinical trials have repetitively shown the promising effects of MR blockers in these diseases. We and other researchers have identified novel mechanisms of MR activation involved in salt-sensitive hypertension and renal injury, including the obesity-derived overproduction of aldosterone and ligand-independent signaling. Moreover, recent advances in the analysis of cell-specific and context-dependent mechanisms of MR activation in various tissues-including a classic target of aldosterone, aldosterone-sensitive distal nephrons-are now providing new insights. In this review, we summarize recent updates to our understanding of aldosterone-MR signaling, focusing on its role in salt-sensitive hypertension and renal injury.
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Affiliation(s)
- Nobuhiro Ayuzawa
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Toshiro Fujita
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan,Shinshu University School of Medicine, Nagano, Japan,Research Center for Social Systems, Shinshu University, Nagano, Japan
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32
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Murillo-de-Ozores AR, Rodríguez-Gama A, Carbajal-Contreras H, Gamba G, Castañeda-Bueno M. WNK4 kinase: from structure to physiology. Am J Physiol Renal Physiol 2021; 320:F378-F403. [PMID: 33491560 DOI: 10.1152/ajprenal.00634.2020] [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: 12/12/2022] Open
Abstract
With no lysine kinase-4 (WNK4) belongs to a serine-threonine kinase family characterized by the atypical positioning of its catalytic lysine. Despite the fact that WNK4 has been found in many tissues, the majority of its study has revolved around its function in the kidney, specifically as a positive regulator of the thiazide-sensitive NaCl cotransporter (NCC) in the distal convoluted tubule of the nephron. This is explained by the description of gain-of-function mutations in the gene encoding WNK4 that causes familial hyperkalemic hypertension. This disease is mainly driven by increased downstream activation of the Ste20/SPS1-related proline-alanine-rich kinase/oxidative stress responsive kinase-1-NCC pathway, which increases salt reabsorption in the distal convoluted tubule and indirectly impairs renal K+ secretion. Here, we review the large volume of information that has accumulated about different aspects of WNK4 function. We first review the knowledge on WNK4 structure and enumerate the functional domains and motifs that have been characterized. Then, we discuss WNK4 physiological functions based on the information obtained from in vitro studies and from a diverse set of genetically modified mouse models with altered WNK4 function. We then review in vitro and in vivo evidence on the different levels of regulation of WNK4. Finally, we go through the evidence that has suggested how different physiological conditions act through WNK4 to modulate NCC activity.
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Affiliation(s)
- Adrián Rafael Murillo-de-Ozores
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico.,Facultad de Medicina, Universidad Nacional Autónoma de México, Coyoacan, Mexico City, Mexico
| | | | - Héctor Carbajal-Contreras
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico.,Combined Studies Program in Medicine MD/PhD (PECEM), Facultad de Medicina, Universidad Nacional Autónoma de México, Coyoacan, Mexico City, Mexico, Mexico
| | - Gerardo Gamba
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico.,Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico.,Combined Studies Program in Medicine MD/PhD (PECEM), Facultad de Medicina, Universidad Nacional Autónoma de México, Coyoacan, Mexico City, Mexico, Mexico
| | - María Castañeda-Bueno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico.,Combined Studies Program in Medicine MD/PhD (PECEM), Facultad de Medicina, Universidad Nacional Autónoma de México, Coyoacan, Mexico City, Mexico, Mexico
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Chan CH, Wu SN, Bao BY, Li HW, Lu TL. MST3 Involvement in Na + and K + Homeostasis with Increasing Dietary Potassium Intake. Int J Mol Sci 2021; 22:ijms22030999. [PMID: 33498219 PMCID: PMC7863938 DOI: 10.3390/ijms22030999] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/14/2021] [Accepted: 01/15/2021] [Indexed: 02/07/2023] Open
Abstract
K+ loading inhibits NKCC2 (Na-K-Cl cotransporter) and NCC (Na-Cl cotransporter) in the early distal tubules, resulting in Na+ delivery to the late distal convoluted tubules (DCTs). In the DCTs, Na+ entry through ENaC (epithelial Na channel) drives K+ secretion through ROMK (renal outer medullary potassium channel). WNK4 (with-no-lysine 4) regulates the NCC/NKCC2 through SAPK (Ste20-related proline-alanine-rich kinase)/OSR1 (oxidative stress responsive). K+ loading increases intracellular Cl−, which binds to the WNK4, thereby inhibiting autophosphorylation and downstream signals. Acute K+ loading-deactivated NCC was not observed in Cl−-insensitive WNK4 mice, indicating that WNK4 was involved in K+ loading-inhibited NCC activity. However, chronic K+ loading deactivated NCC in Cl−-insensitive WNK4 mice, indicating that other mechanisms may be involved. We previously reported that mammalian Ste20-like protein kinase 3 (MST3/STK24) was expressed mainly in the medullary TAL (thick ascending tubule) and at lower levels in the DCTs. MST3−/− mice exhibited higher ENaC activity, causing hypernatremia and hypertension. To investigate MST3 function in maintaining Na+/K+ homeostasis in kidneys, mice were fed diets containing various concentrations of Na+ and K+. The 2% KCl diets induced less MST3 expression in MST3−/− mice than that in wild-type (WT) mice. The MST3−/− mice had higher WNK4, NKCC2-S130 phosphorylation, and ENaC expression, resulting in lower urinary Na+ and K+ excretion than those of WT mice. Lower urinary Na+ excretion was associated with elevated plasma [Na+] and hypertension. These results suggest that MST3 maintains Na+/K+ homeostasis in response to K+ loading by regulation of WNK4 expression and NKCC2 and ENaC activity.
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Affiliation(s)
- Chee-Hong Chan
- Department of Nephrology, Chang Bing Show Chwan Memorial Hospital, Lukang, Changhua 505, Taiwan;
| | - Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, Tainan 70101, Taiwan;
| | - Bo-Ying Bao
- School of Pharmacy, China Medical University, Taichung 406040, Taiwan;
- Department of Nursing, Asia University, Taichung 41354, Taiwan
| | - Houng-Wei Li
- Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung 406040, Taiwan;
| | - Te-Ling Lu
- School of Pharmacy, China Medical University, Taichung 406040, Taiwan;
- Correspondence:
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34
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Preston RA, Afshartous D, Caizapanta EV, Materson BJ, Rodco R, Alonso E, Alonso AB. Thiazide-Sensitive NCC (Sodium-Chloride Cotransporter) in Human Metabolic Syndrome: Sodium Sensitivity and Potassium-Induced Natriuresis. Hypertension 2021; 77:447-460. [PMID: 33390050 DOI: 10.1161/hypertensionaha.120.15933] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The thiazide-sensitive sodium-chloride cotransporter (NCC;SLC12A3) is central to sodium and blood pressure regulation. Metabolic syndrome induces NCC upregulation generating sodium-sensitive hypertension in experimental animal models. We tested the role of NCC in sodium sensitivity in hypertensive humans with metabolic syndrome. Conversely, oral potassium induces NCC downregulation producing potassium-induced natriuresis. We determined the time course and magnitude of potassium-induced natriuresis compared with the natriuresis following hydrochlorothiazide (HCTZ) as a reference standard. We studied 19 obese hypertensive humans with metabolic syndrome during 13-day inpatient confinement. We determined sodium sensitivity by change in 24-hour mean systolic pressure by automated monitor from days 5 (low sodium) to 10 (high sodium). We determined NCC activity by standard 50 mg HCTZ sensitivity test (day 11). We determined potassium-induced natriuresis following 35 mmol KCl (day 13). We determined (1) whether NCC activity was greater in sodium-sensitive versus sodium-resistant participants and correlated with sodium sensitivity and (2) time course and magnitude of potassium-induced natriuresis following 35 mmol KCl directly compared with 50 mg HCTZ. NCC activity was not greater in sodium-sensitive versus sodium-resistant humans and did not correlate with sodium sensitivity. Thirty-five-millimoles KCl produced a rapid natriuresis approximately half that of 50 mg HCTZ with a greater kaliuresis. Our investigation tested a key hypothesis regarding NCC activity in human hypertension and characterized potassium-induced natriuresis following 35 mmol KCl compared with 50 mg HCTZ. In obese hypertensive adults with metabolic syndrome ingesting a high-sodium diet, 35 mmol KCl had a net natriuretic effect approximately half that of 50 mg HCTZ.
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Affiliation(s)
- Richard A Preston
- From the Clinical Pharmacology Research Unit, Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine, University of Miami, FL (R.A.P., D.A., E.V.C., B.J.M., R.R., E.A., A.B.A.).,University of Miami Clinical and Translational Science Institutes, FL (R.A.P.).,Peggy and Harold Katz Family Drug Discovery Center, Miami, FL (R.A.P.)
| | - David Afshartous
- From the Clinical Pharmacology Research Unit, Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine, University of Miami, FL (R.A.P., D.A., E.V.C., B.J.M., R.R., E.A., A.B.A.)
| | - Evelyn V Caizapanta
- From the Clinical Pharmacology Research Unit, Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine, University of Miami, FL (R.A.P., D.A., E.V.C., B.J.M., R.R., E.A., A.B.A.)
| | - Barry J Materson
- From the Clinical Pharmacology Research Unit, Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine, University of Miami, FL (R.A.P., D.A., E.V.C., B.J.M., R.R., E.A., A.B.A.)
| | - Rolando Rodco
- From the Clinical Pharmacology Research Unit, Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine, University of Miami, FL (R.A.P., D.A., E.V.C., B.J.M., R.R., E.A., A.B.A.)
| | - Eileen Alonso
- From the Clinical Pharmacology Research Unit, Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine, University of Miami, FL (R.A.P., D.A., E.V.C., B.J.M., R.R., E.A., A.B.A.)
| | - Alberto B Alonso
- From the Clinical Pharmacology Research Unit, Division of Clinical Pharmacology, Department of Medicine, Miller School of Medicine, University of Miami, FL (R.A.P., D.A., E.V.C., B.J.M., R.R., E.A., A.B.A.)
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35
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Wei KY, Gritter M, Vogt L, de Borst MH, Rotmans JI, Hoorn EJ. Dietary potassium and the kidney: lifesaving physiology. Clin Kidney J 2020; 13:952-968. [PMID: 33391739 PMCID: PMC7769543 DOI: 10.1093/ckj/sfaa157] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Indexed: 02/07/2023] Open
Abstract
Potassium often has a negative connotation in Nephrology as patients with chronic kidney disease (CKD) are prone to develop hyperkalaemia. Approaches to the management of chronic hyperkalaemia include a low potassium diet or potassium binders. Yet, emerging data indicate that dietary potassium may be beneficial for patients with CKD. Epidemiological studies have shown that a higher urinary potassium excretion (as proxy for higher dietary potassium intake) is associated with lower blood pressure (BP) and lower cardiovascular risk, as well as better kidney outcomes. Considering that the composition of our current diet is characterized by a high sodium and low potassium content, increasing dietary potassium may be equally important as reducing sodium. Recent studies have revealed that dietary potassium modulates the activity of the thiazide-sensitive sodium-chloride cotransporter in the distal convoluted tubule (DCT). The DCT acts as a potassium sensor to control the delivery of sodium to the collecting duct, the potassium-secreting portion of the kidney. Physiologically, this allows immediate kaliuresis after a potassium load, and conservation of potassium during potassium deficiency. Clinically, it provides a novel explanation for the inverse relationship between dietary potassium and BP. Moreover, increasing dietary potassium intake can exert BP-independent effects on the kidney by relieving the deleterious effects of a low potassium diet (inflammation, oxidative stress and fibrosis). The aim of this comprehensive review is to link physiology with clinical medicine by proposing that the same mechanisms that allow us to excrete an acute potassium load also protect us from hypertension, cardiovascular disease and CKD.
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Affiliation(s)
- Kuang-Yu Wei
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands.,Department of Internal Medicine, Division of Nephrology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Martin Gritter
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Liffert Vogt
- Department of Internal Medicine, Division of Nephrology, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - Martin H de Borst
- Department of Internal Medicine, Division of Nephrology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Joris I Rotmans
- Department of Internal Medicine, Division of Nephrology, Leiden University Medical Center, Leiden, The Netherlands
| | - Ewout J Hoorn
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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36
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Yang L, Frindt G, Xu Y, Uchida S, Palmer LG. Aldosterone-dependent and -independent regulation of Na + and K + excretion and ENaC in mouse kidneys. Am J Physiol Renal Physiol 2020; 319:F323-F334. [PMID: 32628540 DOI: 10.1152/ajprenal.00204.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We investigated the regulation of Na+ and K+ excretion and the epithelial Na+ channel (ENaC) in mice lacking the gene for aldosterone synthase (AS) using clearance methods to assess excretion and electrophysiology and Western blot analysis to test for ENaC activity and processing. After 1 day of dietary Na+ restriction, AS-/- mice lost more Na+ in the urine than AS+/+ mice did. After 1 wk on this diet, both genotypes strongly reduced urinary Na+ excretion, but creatinine clearance decreased only in AS-/- mice. Only AS+/+ animals exhibited increased ENaC function, assessed as amiloride-sensitive whole cell currents in collecting ducts or cleavage of αENaC and γENaC in Western blots. To assess the role of aldosterone in the excretion of a K+ load, animals were fasted overnight and refed with high-K+ or low-K+ diets for 5 h. Both AS+/+ and AS-/- mice excreted a large amount of K+ during this period. In both phenotypes the excretion was benzamil sensitive, indicating increased K+ secretion coupled to ENaC-dependent Na+ reabsorption. However, the increase in plasma K+ under these conditions was much larger in AS-/- animals than in AS+/+ animals. In both groups, cleavage of αENaC and γENaC increased. However, Na+ current measured ex vivo in connecting tubules was enhanced only in AS+/+ mice. We conclude that in the absence of aldosterone, mice can conserve Na+ without ENaC activation but at the expense of diminished glomerular filtration rate. Excretion of a K+ load can be accomplished through aldosterone-independent upregulation of ENaC, but aldosterone is required to excrete the excess K+ without hyperkalemia.
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Affiliation(s)
- Lei Yang
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, New York
| | - Gustavo Frindt
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, New York
| | - Yuanyuan Xu
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, New York.,Department of Cardiology, the Fourth Hospital of Harbin Medical University, Harbin, China
| | - Shinichi Uchida
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Lawrence G Palmer
- Department of Physiology and Biophysics, Weill-Cornell Medical College, New York, New York
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Abstract
Hypokalemia is closely linked with the pathophysiology of primary aldosteronism (PA). Although hypokalemic PA is less common than the normokalemic course of the disease, hypokalemia is of particular importance for the manifestation and development of comorbidities. Specifically, a growing body of evidence demonstrates that hypokalemia in PA patients is associated with a more severe disease course regarding cardiovascular and metabolic morbidity and mortality. It is also well appreciated that low potassium levels per se can promote or exacerbate hypertension. The spectrum of hypokalemia-related symptoms ranges from asymptomatic courses to life-threatening conditions. Hypokalemia is found in 9-37% of all cases of PA with a predominance in patients with aldosterone producing adenoma. Conversely, hypokalemia resolves in almost 100% of cases after both, specific medical or surgical treatment of the disease. However, to date, high-level evidence about the prevalence of primary aldosteronism in a hypokalemic population is missing. Epidemiological data are expected from the recently launched IPAHK+study ("Incidence of Primary Aldosteronism in Patients with Hypokalemia").
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Affiliation(s)
- Sven Gruber
- Klinik für Endokrinologie, Diabetologie und Klinische Ernährung, UniversitätsSpital Zürich, Zurich, Switzerland
| | - Felix Beuschlein
- Klinik für Endokrinologie, Diabetologie und Klinische Ernährung, UniversitätsSpital Zürich, Zurich, Switzerland
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Munich, Germany
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38
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Furusho T, Uchida S, Sohara E. The WNK signaling pathway and salt-sensitive hypertension. Hypertens Res 2020; 43:733-743. [PMID: 32286498 DOI: 10.1038/s41440-020-0437-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 03/11/2020] [Accepted: 03/11/2020] [Indexed: 12/19/2022]
Abstract
The distal nephron of the kidney has a central role in sodium and fluid homeostasis, and disruption of this homeostasis due to mutations of with-no-lysine kinase 1 (WNK1), WNK4, Kelch-like 3 (KLHL3), or Cullin 3 (CUL3) causes pseudohypoaldosteronism type II (PHAII), an inherited hypertensive disease. WNK1 and WNK4 activate the NaCl cotransporter (NCC) at the distal convoluted tubule through oxidative stress-responsive gene 1 (OSR1)/Ste20-related proline-alanine-rich kinase (SPAK), constituting the WNK-OSR1/SPAK-NCC phosphorylation cascade. The level of WNK protein is regulated through degradation by the CUL3-KLHL3 E3 ligase complex. In the normal state, the activity of WNK signaling in the kidney is physiologically regulated by sodium intake to maintain sodium homeostasis in the body. In patients with PHAII, however, because of the defective degradation of WNK kinases, NCC is constitutively active and not properly suppressed by a high salt diet, leading to abnormally increased salt reabsorption and salt-sensitive hypertension. Importantly, recent studies have demonstrated that potassium intake, insulin, and TNFα are also physiological regulators of WNK signaling, suggesting that they contribute to the salt-sensitive hypertension associated with a low potassium diet, metabolic syndrome, and chronic kidney disease, respectively. Moreover, emerging evidence suggests that WNK signaling also has some unique roles in metabolic, cardiovascular, and immunological organs. Here, we review the recent literature and discuss the molecular mechanisms of the WNK signaling pathway and its potential as a therapeutic target.
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Affiliation(s)
- Taisuke Furusho
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Shinichi Uchida
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Eisei Sohara
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
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39
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Shi S, Montalbetti N, Wang X, Rush BM, Marciszyn AL, Baty CJ, Tan RJ, Carattino MD, Kleyman TR. Paraoxonase 3 functions as a chaperone to decrease functional expression of the epithelial sodium channel. J Biol Chem 2020; 295:4950-4962. [PMID: 32079677 DOI: 10.1074/jbc.ra119.011789] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 02/17/2020] [Indexed: 01/11/2023] Open
Abstract
The paraoxonase (PON) family comprises three highly conserved members: PON1, PON2, and PON3. They are orthologs of Caenorhabditis elegans MEC-6, an endoplasmic reticulum-resident chaperone that has a critical role in proper assembly and surface expression of the touch-sensing degenerin channel in nematodes. We have shown recently that MEC-6 and PON2 negatively regulate functional expression of the epithelial Na+ channel (ENaC), suggesting that the chaperone function is conserved within this family. We hypothesized that other PON family members also modulate ion channel expression. Pon3 is specifically expressed in the aldosterone-sensitive distal tubules in the mouse kidney. We found here that knocking down endogenous Pon3 in mouse cortical collecting duct cells enhanced Na+ transport, which was associated with increased γENaC abundance. We further examined Pon3 regulation of ENaC in two heterologous expression systems, Fisher rat thyroid cells and Xenopus oocytes. Pon3 coimmunoprecipitated with each of the three ENaC subunits in Fisher rat thyroid cells. As a result of this interaction, the whole-cell and surface abundance of ENaC α and γ subunits was reduced by Pon3. When expressed in oocytes, Pon3 inhibited ENaC-mediated amiloride-sensitive Na+ currents, in part by reducing the surface expression of ENaC. In contrast, Pon3 did not alter the response of ENaC to chymotrypsin-mediated proteolytic activation or [2-(trimethylammonium)ethyl]methanethiosulfonate-induced activation of αβS518Cγ, suggesting that Pon3 does not affect channel open probability. Together, our results suggest that PON3 regulates ENaC expression by inhibiting its biogenesis and/or trafficking.
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Affiliation(s)
- Shujie Shi
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Nicolas Montalbetti
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Xueqi Wang
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261.,Department of Nephrology, Second Xiangya Hospital of Central South University, Changsha 410011, Hunan, China
| | - Brittney M Rush
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Allison L Marciszyn
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Catherine J Baty
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Roderick J Tan
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Marcelo D Carattino
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261.,Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Thomas R Kleyman
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261.,Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261.,Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
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40
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Nakagawa T, Lanaspa MA, Johnson RJ. The effects of fruit consumption in patients with hyperuricaemia or gout. Rheumatology (Oxford) 2020; 58:1133-1141. [PMID: 31004140 DOI: 10.1093/rheumatology/kez128] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 03/06/2019] [Indexed: 01/05/2023] Open
Abstract
The consumption of fructose has gained increased attention as a potential cause of hyperuricaemia since fructose metabolism produces urate as a byproduct. In addition to sucrose and high fructose corn syrup, fresh fruits also contain fructose, suggesting that patients with hyperuricaemia or gout might also avoid fresh fruit. However, the effect of fruits is complex. Some studies reported that fruit intake was associated with gout flares while other studies showed that fruits rather lowered the risk for gout. Thus, fruits should not be simply viewed as a source of fructose. The complexity of fruits is accounted for by several nutrients existing in fruits. Vitamin C, epicatechin, flavonols, potassium and fibre are all nutrients in fruits, and these factors could modify fructose and urate effects. In this review, we discuss clinical studies evaluating the effect of fruit and fruit juice intake on hyperuricaemia and gout, and propose potential mechanisms for how fruit may influence urate levels.
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Affiliation(s)
- Takahiko Nakagawa
- Department of Nephrology, Rakuwakai Otowa Hospital, Kyoto, Japan.,Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Miguel A Lanaspa
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, USA
| | - Richard J Johnson
- Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO, USA
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41
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Burnier M. Should we eat more potassium to better control blood pressure in hypertension? Nephrol Dial Transplant 2020; 34:184-193. [PMID: 29301002 DOI: 10.1093/ndt/gfx340] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 11/20/2017] [Indexed: 01/04/2023] Open
Abstract
Changes in lifestyle and nutrition are recommended as the first-step approach to the management of hypertension by all national and international guidelines. Today, when considering nutritional factors in hypertension, almost all the attention is focused on the reduction of salt intake to improve blood pressure (BP) control. Changes in potassium intake are only briefly evoked in guidelines. Few physicians actually think about proposing to eat more foods that are high in potassium (fruits, vegetables, nuts) to better control BP. Yet, during the last 40 years, increasing evidence has accumulated demonstrating that increasing potassium intake, either with food products or with supplements, is associated with significant reductions of both systolic and diastolic BP. The hypotensive effect of potassium is particularly marked in patients with hypertension and in subjects with a very high sodium intake, suggesting that potassium counterbalances the effects of sodium. In addition, several meta-analyses have now confirmed that high potassium intake reduces the risk of stroke by ∼ 25%. Finally, increasing potassium in the diet may perhaps be beneficial for some renal patients, as post hoc analyses have suggested that a high potassium intake may retard the decline of renal function in patients with early chronic kidney disease (CKD) stages. However, high potassium intake may be risky and sometimes even dangerous in hypertensive patients with CKD stages 3-5, specifically diabetics. In this context, however, as the level of evidence remains low, more prospective clinical studies are needed. The goal of this review is to discuss the actual evidence that supports the recommendation to eat more potassium in order to better control BP in essential hypertension and to review the restrictions in CKD patients with hypertension.
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Affiliation(s)
- Michel Burnier
- Service of Nephrology and Hypertension, Centre Hospitalier Universitaire Vaudois, University Hospital Lausanne, Lausanne, Switzerland
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42
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Ayuzawa N, Nishimoto M, Ueda K, Hirohama D, Kawarazaki W, Shimosawa T, Marumo T, Fujita T. Two Mineralocorticoid Receptor-Mediated Mechanisms of Pendrin Activation in Distal Nephrons. J Am Soc Nephrol 2020; 31:748-764. [PMID: 32034107 DOI: 10.1681/asn.2019080804] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 12/27/2019] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Regulation of sodium chloride transport in the aldosterone-sensitive distal nephron is essential for fluid homeostasis and BP control. The chloride-bicarbonate exchanger pendrin in β-intercalated cells, along with sodium chloride cotransporter (NCC) in distal convoluted tubules, complementarily regulate sodium chloride handling, which is controlled by the renin-angiotensin-aldosterone system. METHODS Using mice with mineralocorticoid receptor deletion in intercalated cells, we examined the mechanism and roles of pendrin upregulation via mineralocorticoid receptor in two different models of renin-angiotensin-aldosterone system activation. We also used aldosterone-treated NCC knockout mice to examine the role of pendrin regulation in salt-sensitive hypertension. RESULTS Deletion of mineralocorticoid receptor in intercalated cells suppressed the increase in renal pendrin expression induced by either exogenous angiotensin II infusion or endogenous angiotensin II upregulation via salt restriction. When fed a low-salt diet, intercalated cell-specific mineralocorticoid receptor knockout mice with suppression of pendrin upregulation showed BP reduction that was attenuated by compensatory activation of NCC. In contrast, upregulation of pendrin induced by aldosterone excess combined with a high-salt diet was scarcely affected by deletion of mineralocorticoid receptor in intercalated cells, but depended instead on hypokalemic alkalosis through the activated mineralocorticoid receptor-epithelial sodium channel cascade in principal cells. In aldosterone-treated NCC knockout mice showing upregulation of pendrin, potassium supplementation corrected alkalosis and inhibited the pendrin upregulation, thereby lowering BP. CONCLUSIONS In conjunction with NCC, the two pathways of pendrin upregulation, induced by angiotensin II through mineralocorticoid receptor activation in intercalated cells and by alkalosis through mineralocorticoid receptor activation in principal cells, play important roles in fluid homeostasis during salt depletion and salt-sensitive hypertension mediated by aldosterone excess.
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Affiliation(s)
- Nobuhiro Ayuzawa
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan;
| | - Mitsuhiro Nishimoto
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Kohei Ueda
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Daigoro Hirohama
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Wakako Kawarazaki
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Tatsuo Shimosawa
- Department of Clinical Laboratory, School of Medicine, International University of Health and Welfare, Chiba, Japan
| | - Takeshi Marumo
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Toshiro Fujita
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan;
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43
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Penton D, Vohra T, Banki E, Wengi A, Weigert M, Forst AL, Bandulik S, Warth R, Loffing J. Collecting system-specific deletion of Kcnj10 predisposes for thiazide- and low-potassium diet-induced hypokalemia. Kidney Int 2020; 97:1208-1218. [PMID: 32299681 DOI: 10.1016/j.kint.2019.12.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 12/20/2019] [Accepted: 12/20/2019] [Indexed: 12/17/2022]
Abstract
The basolateral potassium channel KCNJ10 (Kir4.1), is expressed in the renal distal convoluted tubule and controls the activity of the thiazide-sensitive sodium chloride cotransporter. Loss-of-function mutations of KCNJ10 cause EAST/SeSAME syndrome with salt wasting and severe hypokalemia. KCNJ10 is also expressed in the principal cells of the collecting system. However, its pathophysiological role in this segment has not been studied in detail. To address this, we generated the mouse model AQP2cre:Kcnj10flox/flox with a deletion of Kcnj10 specifically in the collecting system (collecting system-Kcnj10-knockout). Collecting system-Kcnj10-knockout mice responded normally to standard and high potassium diet. However, this knockout exhibited a higher kaliuresis and lower plasma potassium than control mice when treated with thiazide diuretics. Likewise, collecting systemKcnj10-knockout displayed an inadequately high kaliuresis and renal sodium retention upon dietary potassium restriction. In this condition, these knockout mice became hypokalemic due to insufficient downregulation of the epithelial sodium channel (ENaC) and the renal outer medullary potassium channel (ROMK) in the collecting system. Consistently, the phenotype of collecting system-Kcnj10-knockout was fully abrogated by ENaC inhibition with amiloride and ameliorated by genetic inactivation of ROMK in the collecting system. Thus, KCNJ10 in the collecting system contributes to the renal control of potassium homeostasis by regulating ENaC and ROMK. Hence, impaired KCNJ10 function in the collecting system predisposes for thiazide and low potassium diet-induced hypokalemia and likely contributes to the pathophysiology of renal potassium loss in EAST/SeSAME syndrome.
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Affiliation(s)
- David Penton
- Institute of Anatomy, University of Zurich, Zurich, Switzerland; Swiss National Centre of Competence in Research (NCCR) Kidney Control of Homeostasis (Kidney.CH), Zurich, Switzerland
| | - Twinkle Vohra
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Eszter Banki
- Institute of Anatomy, University of Zurich, Zurich, Switzerland; Swiss National Centre of Competence in Research (NCCR) Kidney Control of Homeostasis (Kidney.CH), Zurich, Switzerland
| | - Agnieszka Wengi
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Maria Weigert
- Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | - Anna-Lena Forst
- Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | - Sascha Bandulik
- Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | - Richard Warth
- Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | - Johannes Loffing
- Institute of Anatomy, University of Zurich, Zurich, Switzerland; Swiss National Centre of Competence in Research (NCCR) Kidney Control of Homeostasis (Kidney.CH), Zurich, Switzerland.
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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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Gu L, Wang J, Zhang DD, Meng X, Zhang Y, Zhang J, Zhang H, Guo X, Lin DH, Wang WH, Gu RM. Inhibition of AT2R and Bradykinin Type II Receptor (BK2R) Compromises High K + Intake-Induced Renal K + Excretion. Hypertension 2019; 75:439-448. [PMID: 31865783 DOI: 10.1161/hypertensionaha.119.13852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The inhibition of Type II angiotensin II receptor (AT2R) or BK2R (bradykinin type II receptor) stimulates basolateral Kir4.1/Kir5.1 in the distal convoluted tubule (DCT) and activates thiazide-sensitive NCC (Na-Cl cotransporter). The aim of the present study is to examine the role of AT2R and BK2R in mediating the effect of HK (high dietary K+) intake on the basolateral K+ channels, NCC, and renal K+ excretion. Feeding mice (male and female) with HK diet for overnight significantly decreased the basolateral K+ conductance, depolarized the DCT membrane, diminished the expression of pNCC (phosphorylated NCC) and tNCC (total NCC), and decreased thiazide-sensitive natriuresis. Overnight HK intake also increased the expression of cleaved ENaC-α and -γ subunits but had no effect on NKCC2 expression. Pretreatment of the mice (male and female) with PD123319 and HOE140 stimulated the expression of tNCC and pNCC, augmented hydrochlorothiazide-induced natriuresis, and increased the negativity of the DCT membrane. The deletion of Kir4.1 not only decreased the NCC activity but also abolished the stimulatory effect of PD123319 and HOE140 perfusion on NCC activity. Moreover, the effect of overnight HK loading on Kir4.1/Kir5.1 in the DCT and NCC expression/activity was compromised in the mice treated with AT2R/BK2R antagonists. Renal clearance study showed that inhibition of AT2R and BK2R impairs renal K+ excretion in response to overnight HK loading, and the mice pretreated with PD123319 and HOE140 were hyperkalemic during HK intake. We conclude that synergistic activation of AT2R and BK2R is required for the effect of overnight HK diet on Kir4.1/Kir5.1 in the DCT and NCC activity.
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Affiliation(s)
- Li Gu
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
| | - JunLin Wang
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
| | - Dan-Dan Zhang
- Department of Pharmacology, New York Medical College, Valhalla (D.-D. Z., D.-H.L, W.-H.W.)
| | - XinXin Meng
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
| | - YunHong Zhang
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
| | - JiaWen Zhang
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
| | - Hao Zhang
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
| | - XiWen Guo
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla (D.-D. Z., D.-H.L, W.-H.W.)
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla (D.-D. Z., D.-H.L, W.-H.W.)
| | - Rui-Min Gu
- From the Department of Physiology, Harbin Medical University, China (L.G., J.W., X.M., Y.Z, J.Z., H.Z., X.G., R.-M.G.)
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46
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Gritter M, Rotmans JI, Hoorn EJ. Role of Dietary K + in Natriuresis, Blood Pressure Reduction, Cardiovascular Protection, and Renoprotection. Hypertension 2019; 73:15-23. [PMID: 30571564 DOI: 10.1161/hypertensionaha.118.11209] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Martin Gritter
- From the Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands (M.G., E.J.H.)
| | - Joris I Rotmans
- Department of Internal Medicine-Nephrology, Leiden University Medical Center, the Netherlands (J.I.R.)
| | - Ewout J Hoorn
- From the Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands (M.G., E.J.H.)
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47
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Frame AA, Farquhar WB, Latulippe ME, McDonough AA, Wainford RD, Wynne BM. Moving the Needle on Hypertension: What Knowledge Is Needed? NUTRITION TODAY 2019; 54:248-256. [PMID: 34092814 PMCID: PMC8174552 DOI: 10.1097/nt.0000000000000375] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
This review highlights the gaps in knowledge and methodological challenges discussed during the Experimental Biology 2019 expert panel session titled "Moving the Needle on Hypertension: What Knowledge Is Needed?" Hypertension is a critical public health burden. Despite a demonstrated benefit of blood pressure reduction on measures of hypertension-related morbidity and mortality, rates for successful blood pressure control remain low. Dietary sodium reduction has been shown to reduce both systolic blood pressure by approximately 3.2 mm Hg and diastolic blood pressure by 2.3 mm Hg, depending on baseline blood pressure and degree of sodium reduction. The updated Dietary Reference Intakes for adults released by the National Academies of Sciences, Engineering, and Medicine include a Chronic Disease Risk Reduction sodium intake level of 2300 mg/d, highlighting the importance of dietary sodium intake in reducing elevated blood pressure and indicating that reducing intakes to this level is expected to reduce blood pressure and risk of cardiovascular disease. The average US daily sodium intake of 3400 mg/d is well above the Chronic Disease Risk Reduction of 2300 mg/d, suggesting that dietary sodium reduction has the potential to significantly improve public health. Although the National Academies of Sciences, Engineering, and Medicine report presents intake recommendations based on a systematic, comprehensive, and thorough evaluation of the evidence, several challenges to moving the needle on hypertension remain. Success will require a more advanced understanding of sodium and potassium physiology, as well as development of the tools needed to effectively address existing research gaps and reduce barriers to sodium intake reduction.
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Affiliation(s)
- Alissa A Frame
- Boston University School of Medicine, Boston, Massachusetts
| | - William B Farquhar
- College of Health Sciences at the University of Delaware, Newark, Delaware
| | | | - Alicia A McDonough
- University of Southern California Keck School of Medicine, Los Angeles, California
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48
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Ivy JR, Jones NK, Costello HM, Mansley MK, Peltz TS, Flatman PW, Bailey MA. Glucocorticoid receptor activation stimulates the sodium-chloride cotransporter and influences the diurnal rhythm of its phosphorylation. Am J Physiol Renal Physiol 2019; 317:F1536-F1548. [PMID: 31588796 PMCID: PMC6962506 DOI: 10.1152/ajprenal.00372.2019] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The sodium-chloride cotransporter (NCC) in the distal convoluted tubule contributes importantly to sodium balance and blood pressure (BP) regulation. NCC phosphorylation determines transport activity and has a diurnal rhythm influenced by glucocorticoids. Disturbing this rhythm induces “nondipping” BP, an abnormality that increases cardiovascular risk. The receptor through which glucocorticoids regulate NCC is not known. In this study, we found that acute administration of corticosterone to male C57BL6 mice doubled NCC phosphorylation without affecting total NCC abundance in both adrenalectomized and adrenal-intact mice. Corticosterone also increased the whole kidney expression of canonical clock genes: period circadian protein homolog 1 (Per1), Per2, cryptochrome 1, and aryl hydrocarbon receptor nuclear translocator-like protein 1. In adrenal-intact mice, chronic blockade of glucocorticoid receptor (GR) with RU486 did not change total NCC but prevented corticosterone-induced NCC phosphorylation and activation of clock genes. Blockade of mineralocorticoid receptor (MR) with spironolactone reduced the total pool of NCC but did not affect stimulation by corticosterone. The diurnal rhythm of NCC phosphorylation, measured at 6-h intervals, was blunted by chronic GR blockade, and a similar dampening of diurnal variation was seen in GR heterozygous null mice. These effects on NCC phosphorylation did not reflect altered rhythmicity of plasma corticosterone or serum and glucocorticoid-induced kinase 1 activity. Both mineralocorticoids and glucocorticoids emerge as regulators of NCC, acting via distinct receptor pathways. MR activation provides maintenance of the NCC protein pool; GR activation dynamically regulates NCC phosphorylation and establishes the diurnal rhythm of NCC activity. This study has implications for circadian BP homeostasis, particularly in individuals with abnormal glucocorticoid signaling as is found in chronic stress and corticosteroid therapy.
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Affiliation(s)
- Jessica Ruth Ivy
- British Heart Foundation Centre for Cardiovascular Science, Edinburgh Medical School, The University of Edinburgh, United Kingdom
| | - Natalie K Jones
- British Heart Foundation Centre for Cardiovascular Science, Edinburgh Medical School, The University of Edinburgh, United Kingdom
| | - Hannah M Costello
- British Heart Foundation Centre for Cardiovascular Science, Edinburgh Medical School, The University of Edinburgh, United Kingdom
| | - Morag K Mansley
- British Heart Foundation Centre for Cardiovascular Science, Edinburgh Medical School, The University of Edinburgh, United Kingdom
| | - Theresa S Peltz
- British Heart Foundation Centre for Cardiovascular Science, Edinburgh Medical School, The University of Edinburgh, United Kingdom
| | - Peter W Flatman
- British Heart Foundation Centre for Cardiovascular Science, Edinburgh Medical School, The University of Edinburgh, United Kingdom
| | - Matthew A Bailey
- British Heart Foundation Centre for Cardiovascular Science, Edinburgh Medical School, The University of Edinburgh, United Kingdom
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49
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Li J, Xu S, Yang L, Yang J, Wang CJ, Weinstein AM, Palmer LG, Wang T. Sex difference in kidney electrolyte transport II: impact of K + intake on thiazide-sensitive cation excretion in male and female mice. Am J Physiol Renal Physiol 2019; 317:F967-F977. [PMID: 31390232 PMCID: PMC6843050 DOI: 10.1152/ajprenal.00125.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/15/2019] [Accepted: 07/22/2019] [Indexed: 11/22/2022] Open
Abstract
We studied sex differences in response to high K+ (HK) intake on thiazide-sensitive cation (Na+ and K+) excretion in wild-type (WT) and ANG II receptor subtype 1a (AT1aR) knockout (KO) mice. Renal clearance experiments were performed to examine Na+-Cl- cotransporter (NCC) activity on mice fed with control and HK (5% KCl, 7 days) diets. Hydrochlorothiazide (HCTZ)-induced changes in urine volume, glomerular filtration rate, absolute Na+ and K+ excretion, and fractional excretion were compared. HK-induced changes in NCC, Na+/H+ exchanger isoform 3 (NHE3), and ENaC expression were examined by Western blot analysis. In WT animals under the control diet, HCTZ-induced cation excretion was greater in female animals, reflecting larger increases in Na+ excretion, since there was little sex difference in HCTZ-induced K+ excretion. Under the HK diet, the sex difference in HCTZ-induced cation excretion was reduced because of larger increments in K+ excretion in male animals. The fraction of K+ excretion was 57 ± 5% in male WT animals and 36 ± 4% in female WT animals (P < 0.05), but this difference was absent in AT1aR KO mice. NCC abundance was higher in female animals than in male animals but decreased by similar fractions on HK diet. NHE3 abundance decreased, whereas cleaved forms of γ-ENaC increased, with HK in all groups; these changes were similar in male and female animals and were not significantly affected by AT1aR ablation. These results indicate that, with the HK diet, male animals display greater distal Na+ delivery and greater activation of K+ secretion mechanisms, all suggesting a more powerful male adaptation to HK intake.
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Affiliation(s)
- Jing Li
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| | - Shuhua Xu
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| | - Lei Yang
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, Ithaca, New York
| | - Janey Yang
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| | - Claire J Wang
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| | - Alan M Weinstein
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, Ithaca, New York
| | - Lawrence G Palmer
- Department of Physiology and Biophysics, Weill Medical College of Cornell University, Ithaca, New York
| | - Tong Wang
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
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50
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Wu P, Gao ZX, Zhang DD, Su XT, Wang WH, Lin DH. Deletion of Kir5.1 Impairs Renal Ability to Excrete Potassium during Increased Dietary Potassium Intake. J Am Soc Nephrol 2019; 30:1425-1438. [PMID: 31239388 PMCID: PMC6683724 DOI: 10.1681/asn.2019010025] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/24/2019] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The basolateral potassium channel in the distal convoluted tubule (DCT), comprising the inwardly rectifying potassium channel Kir4.1/Kir5.1 heterotetramer, plays a key role in mediating the effect of dietary potassium intake on the thiazide-sensitive NaCl cotransporter (NCC). The role of Kir5.1 (encoded by Kcnj16) in mediating effects of dietary potassium intake on the NCC and renal potassium excretion is unknown. METHODS We used electrophysiology, renal clearance, and immunoblotting to study Kir4.1 in the DCT and NCC in Kir5.1 knockout (Kcnj16-/- ) and wild-type (Kcnj16+/+ ) mice fed with normal, high, or low potassium diets. RESULTS We detected a 40-pS and 20-pS potassium channel in the basolateral membrane of the DCT in wild-type and knockout mice, respectively. Compared with wild-type, Kcnj16-/- mice fed a normal potassium diet had higher basolateral potassium conductance, a more negative DCT membrane potential, higher expression of phosphorylated NCC (pNCC) and total NCC (tNCC), and augmented thiazide-induced natriuresis. Neither high- nor low-potassium diets affected the basolateral DCT's potassium conductance and membrane potential in Kcnj16-/- mice. Although high potassium reduced and low potassium increased the expression of pNCC and tNCC in wild-type mice, these effects were absent in Kcnj16-/- mice. High potassium intake inhibited and low intake augmented thiazide-induced natriuresis in wild-type but not in Kcnj16-/- mice. Compared with wild-type, Kcnj16-/- mice with normal potassium intake had slightly lower plasma potassium but were more hyperkalemic with prolonged high potassium intake and more hypokalemic during potassium restriction. CONCLUSIONS Kir5.1 is essential for dietary potassium's effect on NCC and for maintaining potassium homeostasis.
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Affiliation(s)
- Peng Wu
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Zhong-Xiuzi Gao
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dan-Dan Zhang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Xiao-Tong Su
- Department of Pharmacology, 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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