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Penton D, Czogalla J, Wengi A, Himmerkus N, Loffing-Cueni D, Carrel M, Rajaram RD, Staub O, Bleich M, Schweda F, Loffing J. Extracellular K + rapidly controls NaCl cotransporter phosphorylation in the native distal convoluted tubule by Cl - -dependent and independent mechanisms. J Physiol 2016; 594:6319-6331. [PMID: 27457700 DOI: 10.1113/jp272504] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 07/14/2016] [Indexed: 12/12/2022] Open
Abstract
KEY POINTS High dietary potassium (K+ ) intake dephosphorylates and inactivates the NaCl cotransporter (NCC) in the renal distal convoluted tubule (DCT). Using several ex vivo models, we show that physiological changes in extracellular K+ , similar to those occurring after a K+ rich diet, are sufficient to promote a very rapid dephosphorylation of NCC in native DCT cells. Although the increase of NCC phosphorylation upon decreased extracellular K+ appears to depend on cellular Cl- fluxes, the rapid NCC dephosphorylation in response to increased extracellular K+ is not Cl- -dependent. The Cl- -dependent pathway involves the SPAK/OSR1 kinases, whereas the Cl- independent pathway may include additional signalling cascades. ABSTRACT A high dietary potassium (K+ ) intake causes a rapid dephosphorylation, and hence inactivation, of the thiazide-sensitive NaCl cotransporter (NCC) in the renal distal convoluted tubule (DCT). Based on experiments in heterologous expression systems, it was proposed that changes in extracellular K+ concentration ([K+ ]ex ) modulate NCC phosphorylation via a Cl- -dependent modulation of the with no lysine (K) kinases (WNK)-STE20/SPS-1-44 related proline-alanine-rich protein kinase (SPAK)/oxidative stress-related kinase (OSR1) kinase pathway. We used the isolated perfused mouse kidney technique and ex vivo preparations of mouse kidney slices to test the physiological relevance of this model on native DCT. We demonstrate that NCC phosphorylation inversely correlates with [K+ ]ex , with the most prominent effects occurring around physiological plasma [K+ ]. Cellular Cl- conductances and the kinases SPAK/OSR1 are involved in the phosphorylation of NCC under low [K+ ]ex . However, NCC dephosphorylation triggered by high [K+ ]ex is neither blocked by removing extracellular Cl- , nor by the Cl- channel blocker 4,4'-diisothiocyano-2,2'-stilbenedisulphonic acid. The response to [K+ ]ex on a low extracellular chloride concentration is also independent of significant changes in SPAK/OSR1 phosphorylation. Thus, in the native DCT, [K+ ]ex directly and rapidly controls NCC phosphorylation by Cl- -dependent and independent pathways that involve the kinases SPAK/OSR1 and a yet unidentified additional signalling mechanism.
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Affiliation(s)
- David Penton
- Institute of Anatomy, University of Zurich, Zurich, Switzerland.,Swiss National Centre of Competence in Research 'Kidney Control of Homeostasis', University of Zurich, Zurich, Switzerland
| | - Jan Czogalla
- Institute of Anatomy, University of Zurich, Zurich, Switzerland.,Swiss National Centre of Competence in Research 'Kidney Control of Homeostasis', University of Zurich, Zurich, Switzerland
| | - Agnieszka Wengi
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Nina Himmerkus
- Institute of Physiology, Christian-Albrecht University, Kiel, Germany
| | | | - Monique Carrel
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Renuga Devi Rajaram
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,Swiss National Centre of Competence in Research 'Kidney Control of Homeostasis', University of Zurich, Zurich, Switzerland
| | - Olivier Staub
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,Swiss National Centre of Competence in Research 'Kidney Control of Homeostasis', University of Zurich, Zurich, Switzerland
| | - Markus Bleich
- Institute of Physiology, Christian-Albrecht University, Kiel, Germany
| | - Frank Schweda
- Institute of Physiology, University of Regensburg, Regensburg, Germany
| | - Johannes Loffing
- Institute of Anatomy, University of Zurich, Zurich, Switzerland. .,Swiss National Centre of Competence in Research 'Kidney Control of Homeostasis', University of Zurich, Zurich, Switzerland.
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52
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Veiras LC, Han J, Ralph DL, McDonough AA. Potassium Supplementation Prevents Sodium Chloride Cotransporter Stimulation During Angiotensin II Hypertension. Hypertension 2016; 68:904-12. [PMID: 27600183 DOI: 10.1161/hypertensionaha.116.07389] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 05/27/2016] [Indexed: 01/06/2023]
Abstract
Angiotensin II (AngII) hypertension increases distal tubule Na-Cl cotransporter (NCC) abundance and phosphorylation (NCCp), as well as epithelial Na(+) channel abundance and activating cleavage. Acutely raising plasma [K(+)] by infusion or ingestion provokes a rapid decrease in NCCp that drives a compensatory kaliuresis. The first aim tested whether acutely raising plasma [K(+)] with a single 3-hour 2% potassium meal would lower NCCp in Sprague-Dawley rats after 14 days of AngII (400 ng/kg per minute). The potassium-rich meal neither decreased NCCp nor increased K(+) excretion. AngII-infused rats exhibited lower plasma [K(+)] versus controls (3.6±0.2 versus 4.5±0.1 mmol/L; P<0.05), suggesting that AngII-mediated epithelial Na(+) channel activation provokes K(+) depletion. The second aim tested whether doubling dietary potassium intake from 1% (A1K) to 2% (A2K) would prevent K(+) depletion during AngII infusion and, thus, prevent NCC accumulation. A2K-fed rats exhibited normal plasma [K(+)] and 2-fold higher K(+) excretion and plasma [aldosterone] versus A1K. In A1K rats, NCC, NCCpS71, and NCCpT53 abundance increased 1.5- to 3-fold versus controls (P<0.05). The rise in NCC and NCCp abundance was prevented in the A2K rats, yet blood pressure did not significantly decrease. Epithelial Na(+) channel subunit abundance and cleavage increased 1.5- to 3-fold in both A1K and A2K; ROMK (renal outer medulla K(+) channel abundance) abundance was unaffected by AngII or dietary K(+) In summary, the accumulation and phosphorylation of NCC seen during chronic AngII infusion hypertension is likely secondary to potassium deficiency driven by epithelial Na(+) channel stimulation.
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Affiliation(s)
- Luciana C Veiras
- From the Department of Cell and Neurobiology, Keck School of Medicine of USC, Los Angeles, CA
| | - Jiyang Han
- From the Department of Cell and Neurobiology, Keck School of Medicine of USC, Los Angeles, CA
| | - Donna L Ralph
- From the Department of Cell and Neurobiology, Keck School of Medicine of USC, Los Angeles, CA
| | - Alicia A McDonough
- From the Department of Cell and Neurobiology, Keck School of Medicine of USC, Los Angeles, CA.
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53
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Walter C, Tanfous MB, Igoudjil K, Salhi A, Escher G, Crambert G. H,K-ATPase type 2 contributes to salt-sensitive hypertension induced by K(+) restriction. Pflugers Arch 2016; 468:1673-83. [PMID: 27562425 DOI: 10.1007/s00424-016-1872-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 08/15/2016] [Accepted: 08/17/2016] [Indexed: 01/24/2023]
Abstract
In industrialized countries, a large part of the population is daily exposed to low K(+) intake, a situation correlated with the development of salt-sensitive hypertension. Among many processes, adaptation to K(+)-restriction involves the stimulation of H,K-ATPase type 2 (HKA2) in the kidney and colon and, in this study, we have investigated whether HKA2 also contributes to the determination of blood pressure (BP). By using wild-type (WT) and HKA2-null mice (HKA2 KO), we showed that after 4 days of K(+) restriction, WT remain normokalemic and normotensive (112 ± 3 mmHg) whereas HKA2 KO mice exhibit hypokalemia and hypotension (104 ± 2 mmHg). The decrease of BP in HKA2 KO is due to the absence of NaCl-cotransporter (NCC) stimulation, leading to renal loss of salt and decreased extracellular volume (by 20 %). These effects are likely related to the renal resistance to vasopressin observed in HKA2 KO that may be explained, in part by the increased production of prostaglandin E2 (PGE2). In WT, the stimulation of NCC induced by K(+)-restriction is responsible for the elevation in BP when salt intake increases, an effect blunted in HKA2-null mice. The presence of an activated HKA2 is therefore required to limit the decrease in plasma [K(+)] but also contributes to the development of salt-sensitive hypertension.
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Affiliation(s)
- Christine Walter
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, Université Paris Descartes, F-75006, Paris, France.,CNRS ERL 8228 - Centre de Recherche des Cordeliers - Laboratoire de Métabolisme et Physiologie Rénale, F-75006, Paris, France
| | - Mariem Ben Tanfous
- Faculté des Sciences de Tunis El Manar, Campus Universitaire 2092, El Manar Tunis, Tunisie
| | - Katia Igoudjil
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, Université Paris Descartes, F-75006, Paris, France.,CNRS ERL 8228 - Centre de Recherche des Cordeliers - Laboratoire de Métabolisme et Physiologie Rénale, F-75006, Paris, France
| | - Amel Salhi
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, Université Paris Descartes, F-75006, Paris, France.,CNRS ERL 8228 - Centre de Recherche des Cordeliers - Laboratoire de Métabolisme et Physiologie Rénale, F-75006, Paris, France
| | - Geneviève Escher
- Departement für Nephrologie, Hypertonie und klinische Pharmakologie, Universitätsspital Bern - Inselspital, CH-3010, Bern, Switzerland
| | - Gilles Crambert
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, Université Paris Descartes, F-75006, Paris, France. .,CNRS ERL 8228 - Centre de Recherche des Cordeliers - Laboratoire de Métabolisme et Physiologie Rénale, F-75006, Paris, France.
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54
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Boscardin E, Alijevic O, Hummler E, Frateschi S, Kellenberger S. The function and regulation of acid-sensing ion channels (ASICs) and the epithelial Na(+) channel (ENaC): IUPHAR Review 19. Br J Pharmacol 2016; 173:2671-701. [PMID: 27278329 DOI: 10.1111/bph.13533] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 05/19/2016] [Accepted: 06/02/2016] [Indexed: 12/30/2022] Open
Abstract
Acid-sensing ion channels (ASICs) and the epithelial Na(+) channel (ENaC) are both members of the ENaC/degenerin family of amiloride-sensitive Na(+) channels. ASICs act as proton sensors in the nervous system where they contribute, besides other roles, to fear behaviour, learning and pain sensation. ENaC mediates Na(+) reabsorption across epithelia of the distal kidney and colon and of the airways. ENaC is a clinically used drug target in the context of hypertension and cystic fibrosis, while ASIC is an interesting potential target. Following a brief introduction, here we will review selected aspects of ASIC and ENaC function. We discuss the origin and nature of pH changes in the brain and the involvement of ASICs in synaptic signalling. We expose how in the peripheral nervous system, ASICs cover together with other ion channels a wide pH range as proton sensors. We introduce the mechanisms of aldosterone-dependent ENaC regulation and the evidence for an aldosterone-independent control of ENaC activity, such as regulation by dietary K(+) . We then provide an overview of the regulation of ENaC by proteases, a topic of increasing interest over the past few years. In spite of the profound differences in the physiological and pathological roles of ASICs and ENaC, these channels share many basic functional and structural properties. It is likely that further research will identify physiological contexts in which ASICs and ENaC have similar or overlapping roles.
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Affiliation(s)
- Emilie Boscardin
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Omar Alijevic
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Edith Hummler
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
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55
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Lou Y, Zhang F, Luo Y, Wang L, Huang S, Jin F. Serum and Glucocorticoid Regulated Kinase 1 in Sodium Homeostasis. Int J Mol Sci 2016; 17:ijms17081307. [PMID: 27517916 PMCID: PMC5000704 DOI: 10.3390/ijms17081307] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/02/2016] [Accepted: 08/03/2016] [Indexed: 12/13/2022] Open
Abstract
The ubiquitously expressed serum and glucocorticoid regulated kinase 1 (SGK1) is tightly regulated by osmotic and hormonal signals, including glucocorticoids and mineralocorticoids. Recently, SGK1 has been implicated as a signal hub for the regulation of sodium transport. SGK1 modulates the activities of multiple ion channels and carriers, such as epithelial sodium channel (ENaC), voltage-gated sodium channel (Nav1.5), sodium hydrogen exchangers 1 and 3 (NHE1 and NHE3), sodium-chloride symporter (NCC), and sodium-potassium-chloride cotransporter 2 (NKCC2); as well as the sodium-potassium adenosine triphosphatase (Na+/K+-ATPase) and type A natriuretic peptide receptor (NPR-A). Accordingly, SGK1 is implicated in the physiology and pathophysiology of Na+ homeostasis. Here, we focus particularly on recent findings of SGK1’s involvement in Na+ transport in renal sodium reabsorption, hormone-stimulated salt appetite and fluid balance and discuss the abnormal SGK1-mediated Na+ reabsorption in hypertension, heart disease, edema with diabetes, and embryo implantation failure.
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Affiliation(s)
- Yiyun Lou
- Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310006, Zhejiang, China.
- Department of Gynaecology, Hangzhou Hospital of Traditional Chinese Medicine, Hangzhou 310007, Zhejiang, China.
| | - Fan Zhang
- Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310006, Zhejiang, China.
| | - Yuqin Luo
- Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310006, Zhejiang, China.
| | - Liya Wang
- Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310006, Zhejiang, China.
| | - Shisi Huang
- Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310006, Zhejiang, China.
| | - Fan Jin
- Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310006, Zhejiang, China.
- Key Laboratory of Reproductive Genetics, National Ministry of Education (Zhejiang University), Women's Reproductive Healthy Laboratory of Zhejiang Province, Hangzhou 310058, Zhejiang, China.
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56
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Unique chloride-sensing properties of WNK4 permit the distal nephron to modulate potassium homeostasis. Kidney Int 2016; 89:127-34. [PMID: 26422504 PMCID: PMC4814375 DOI: 10.1038/ki.2015.289] [Citation(s) in RCA: 188] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 07/13/2015] [Accepted: 07/31/2015] [Indexed: 11/09/2022]
Abstract
Dietary potassium deficiency activates thiazide-sensitive sodium chloride cotransport along the distal nephron. This may explain, in part, the hypertension and cardiovascular mortality observed in individuals who consume a low-potassium diet. Recent data suggest that plasma potassium affects the distal nephron directly by influencing intracellular chloride, an inhibitor of the with-no-lysine kinase (WNK)-Ste20p-related proline- and alanine-rich kinase (SPAK) pathway. As previous studies used extreme dietary manipulations, we sought to determine whether the relationship between potassium and NaCl cotransporter (NCC) is physiologically relevant and clarify the mechanisms involved. We report that modest changes in both dietary and plasma potassium affect NCC in vivo. Kinase assay studies showed that chloride inhibits WNK4 kinase activity at lower concentrations than it inhibits activity of WNK1 or WNK3. Also, chloride inhibited WNK4 within the range of distal cell chloride concentration. Mutation of a previously identified WNK chloride-binding motif converted WNK4 effects on SPAK from inhibitory to stimulatory in mammalian cells. Disruption of this motif in WNKs 1, 3, and 4 had different effects on NCC, consistent with the three WNKs having different chloride sensitivities. Thus, potassium effects on NCC are graded within the physiological range, which explains how unique chloride-sensing properties of WNK4 enable it to mediate effects of potassium on NCC in vivo.
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57
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Terker AS, Yarbrough B, Ferdaus MZ, Lazelle RA, Erspamer KJ, Meermeier NP, Park HJ, McCormick JA, Yang CL, Ellison DH. Direct and Indirect Mineralocorticoid Effects Determine Distal Salt Transport. J Am Soc Nephrol 2015; 27:2436-45. [PMID: 26712527 DOI: 10.1681/asn.2015070815] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 11/17/2015] [Indexed: 11/03/2022] Open
Abstract
Excess aldosterone is an important contributor to hypertension and cardiovascular disease. Conversely, low circulating aldosterone causes salt wasting and hypotension. Aldosterone activates mineralocorticoid receptors (MRs) to increase epithelial sodium channel (ENaC) activity. However, aldosterone may also stimulate the thiazide-sensitive Na(+)-Cl(-) cotransporter (NCC). Here, we generated mice in which MRs could be deleted along the nephron to test this hypothesis. These kidney-specific MR-knockout mice exhibited salt wasting, low BP, and hyperkalemia. Notably, we found evidence of deficient apical orientation and cleavage of ENaC, despite the salt wasting. Although these mice also exhibited deficient NCC activity, NCC could be stimulated by restricting dietary potassium, which also returned BP to control levels. Together, these results indicate that MRs regulate ENaC directly, but modulation of NCC is mediated by secondary changes in plasma potassium concentration. Electrolyte balance and BP seem to be determined, therefore, by a delicate interplay between direct and indirect mineralocorticoid actions in the distal nephron.
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Affiliation(s)
- Andrew S Terker
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Bethzaida Yarbrough
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Mohammed Z Ferdaus
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Rebecca A Lazelle
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Kayla J Erspamer
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Nicholas P Meermeier
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Hae J Park
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - James A McCormick
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Chao-Ling Yang
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and Renal Section, Veterans Affairs Portland Health Care System, Portland, Oregon
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and Renal Section, Veterans Affairs Portland Health Care System, Portland, Oregon
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58
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Terker AS, Ellison DH. Renal mineralocorticoid receptor and electrolyte homeostasis. Am J Physiol Regul Integr Comp Physiol 2015; 309:R1068-70. [PMID: 26136532 PMCID: PMC4839474 DOI: 10.1152/ajpregu.00135.2015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 06/25/2015] [Indexed: 11/22/2022]
Abstract
The renal mineralocorticoid receptor (MR) is a steroid hormone receptor essential for maintaining electrolyte homeostasis. Its role in mediating effects of aldosterone was likely vital in enabling the evolution of terrestrial life. Dysregulated aldosterone-MR signaling has been identified as the cause of multiple clinical diseases, suggesting the physiological importance of the MR. While the physiology of this pathway has been studied for over 60 years, only more recently have genetic mouse models been available to dissect its function in vivo. This review will focus on recent advances in our knowledge of MR function with an emphasis on these models.
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Affiliation(s)
- Andrew S Terker
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and Veteran Affairs Portland Health Care System, Portland, Oregon
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59
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Ellison DH, Terker AS, Gamba G. Potassium and Its Discontents: New Insight, New Treatments. J Am Soc Nephrol 2015; 27:981-9. [PMID: 26510885 DOI: 10.1681/asn.2015070751] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Hyperkalemia is common in patients with impaired kidney function or who take drugs that inhibit the renin-angiotensin-aldosterone axis. During the past decade, substantial advances in understanding how the body controls potassium excretion have been made, which may lead to improved standard of care for these patients. Renal potassium disposition is primarily handled by a short segment of the nephron, comprising part of the distal convoluted tubule and the connecting tubule, and regulation results from the interplay between aldosterone and plasma potassium. When dietary potassium intake and plasma potassium are low, the electroneutral sodium chloride cotransporter is activated, leading to salt retention. This effect limits sodium delivery to potassium secretory segments, limiting potassium losses. In contrast, when dietary potassium intake is high, aldosterone is stimulated. Simultaneously, potassium inhibits the sodium chloride cotransporter. Because more sodium is then delivered to potassium secretory segments, primed by aldosterone, kaliuresis results. When these processes are disrupted, hyperkalemia results. Recently, new agents capable of removing potassium from the body and treating hyperkalemia have been tested in clinical trials. This development suggests that more effective and safer approaches to the prevention and treatment of hyperkalemia may be on the horizon.
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Affiliation(s)
- David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; Renal Section, Veterans Affairs Portland Health Care System, Portland, Oregon; and
| | - Andrew S Terker
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Gerardo Gamba
- Molecular Physiology Unit, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, Mexico
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60
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Sohara E, Uchida S. Kelch-like 3/Cullin 3 ubiquitin ligase complex and WNK signaling in salt-sensitive hypertension and electrolyte disorder. Nephrol Dial Transplant 2015; 31:1417-24. [DOI: 10.1093/ndt/gfv259] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 05/22/2015] [Indexed: 12/20/2022] Open
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61
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Penton D, Czogalla J, Loffing J. Dietary potassium and the renal control of salt balance and blood pressure. Pflugers Arch 2015; 467:513-30. [PMID: 25559844 DOI: 10.1007/s00424-014-1673-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 12/10/2014] [Accepted: 12/11/2014] [Indexed: 01/09/2023]
Abstract
Dietary potassium (K(+)) intake has antihypertensive effects, prevents strokes, and improves cardiovascular outcomes. The underlying mechanism for these beneficial effects of high K(+) diets may include vasodilation, enhanced urine flow, reduced renal renin release, and negative sodium (Na(+)) balance. Indeed, several studies demonstrate that dietary K(+) intake induces renal Na(+) loss despite elevated plasma aldosterone. This review briefly highlights the epidemiological and experimental evidences for the effects of dietary K(+) on arterial blood pressure. It discusses the pivotal role of the renal distal tubule for the regulation of urinary K(+) and Na(+) excretion and blood pressure and highlights that it depends on the coordinated interaction of different nephron portions, epithelial cell types, and various ion channels, transporters, and ATPases. Moreover, we discuss the relevance of aldosterone and aldosterone-independent factors in mediating the effects of an altered K(+) intake on renal K(+) and Na(+) handling. Particular focus is given to findings suggesting that an aldosterone-independent downregulation of the thiazide-sensitive NaCl cotransporter significantly contributes to the natriuretic and antihypertensive effect of a K(+)-rich diet. Last but not least, we refer to the complex signaling pathways enabling the kidney to adapt its function to the homeostatic needs in response to an altered K(+) intake. Future work will have to further address the underlying cellular and molecular mechanism and to elucidate, among others, how an altered dietary K(+) intake is sensed and how this signal is transmitted to the different epithelial cells lining the distal tubule.
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Affiliation(s)
- David Penton
- Institute of Anatomy, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
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62
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Terker AS, Zhang C, McCormick JA, Lazelle RA, Zhang C, Meermeier NP, Siler DA, Park HJ, Fu Y, Cohen DM, Weinstein AM, Wang WH, Yang CL, Ellison DH. Potassium modulates electrolyte balance and blood pressure through effects on distal cell voltage and chloride. Cell Metab 2015; 21:39-50. [PMID: 25565204 PMCID: PMC4332769 DOI: 10.1016/j.cmet.2014.12.006] [Citation(s) in RCA: 333] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 10/13/2014] [Accepted: 12/13/2014] [Indexed: 10/24/2022]
Abstract
Dietary potassium deficiency, common in modern diets, raises blood pressure and enhances salt sensitivity. Potassium homeostasis requires a molecular switch in the distal convoluted tubule (DCT), which fails in familial hyperkalemic hypertension (pseudohypoaldosteronism type 2), activating the thiazide-sensitive NaCl cotransporter, NCC. Here, we show that dietary potassium deficiency activates NCC, even in the setting of high salt intake, thereby causing sodium retention and a rise in blood pressure. The effect is dependent on plasma potassium, which modulates DCT cell membrane voltage and, in turn, intracellular chloride. Low intracellular chloride stimulates WNK kinases to activate NCC, limiting potassium losses, even at the expense of increased blood pressure. These data show that DCT cells, like adrenal cells, sense potassium via membrane voltage. In the DCT, hyperpolarization activates NCC via WNK kinases, whereas in the adrenal gland, it inhibits aldosterone secretion. These effects work in concert to maintain potassium homeostasis.
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MESH Headings
- Animals
- Blood Pressure/drug effects
- Cell Line
- Chlorides/metabolism
- Electrolytes/urine
- Humans
- Kidney Tubules, Distal/metabolism
- Membrane Potentials/drug effects
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Minor Histocompatibility Antigens
- Potassium/blood
- Potassium/metabolism
- Potassium Channels, Inwardly Rectifying/genetics
- Potassium Channels, Inwardly Rectifying/metabolism
- Potassium, Dietary/pharmacology
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Pseudohypoaldosteronism/metabolism
- Pseudohypoaldosteronism/pathology
- Sodium Chloride, Dietary/pharmacology
- Solute Carrier Family 12, Member 3/deficiency
- Solute Carrier Family 12, Member 3/genetics
- Solute Carrier Family 12, Member 3/metabolism
- WNK Lysine-Deficient Protein Kinase 1
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Affiliation(s)
- Andrew S Terker
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Chong Zhang
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR 97239, USA; Department of Nephrology, Xinhua Hostpital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - James A McCormick
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Rebecca A Lazelle
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Chengbiao Zhang
- Department of Pharmacology, New York Medical College, Valhalla, NY 10595, USA
| | - Nicholas P Meermeier
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Dominic A Siler
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR 97239, USA
| | - Hae J Park
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Yi Fu
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - David M Cohen
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR 97239, USA; VA Portland Health Care System, Portland, OR 97239, USA
| | - Alan M Weinstein
- Department of Physiology and Biophysics, Weil Medical College, New York, NY 10065, USA
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, NY 10595, USA
| | - Chao-Ling Yang
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR 97239, USA; VA Portland Health Care System, Portland, OR 97239, USA
| | - David H Ellison
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR 97239, USA; VA Portland Health Care System, Portland, OR 97239, USA.
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Abstract
The distal convoluted tubule (DCT) is a short nephron segment, interposed between the macula densa and collecting duct. Even though it is short, it plays a key role in regulating extracellular fluid volume and electrolyte homeostasis. DCT cells are rich in mitochondria, and possess the highest density of Na+/K+-ATPase along the nephron, where it is expressed on the highly amplified basolateral membranes. DCT cells are largely water impermeable, and reabsorb sodium and chloride across the apical membrane via electroneurtral pathways. Prominent among this is the thiazide-sensitive sodium chloride cotransporter, target of widely used diuretic drugs. These cells also play a key role in magnesium reabsorption, which occurs predominantly, via a transient receptor potential channel (TRPM6). Human genetic diseases in which DCT function is perturbed have provided critical insights into the physiological role of the DCT, and how transport is regulated. These include Familial Hyperkalemic Hypertension, the salt-wasting diseases Gitelman syndrome and EAST syndrome, and hereditary hypomagnesemias. The DCT is also established as an important target for the hormones angiotensin II and aldosterone; it also appears to respond to sympathetic-nerve stimulation and changes in plasma potassium. Here, we discuss what is currently known about DCT physiology. Early studies that determined transport rates of ions by the DCT are described, as are the channels and transporters expressed along the DCT with the advent of molecular cloning. Regulation of expression and activity of these channels and transporters is also described; particular emphasis is placed on the contribution of genetic forms of DCT dysregulation to our understanding.
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Affiliation(s)
- James A McCormick
- Division of Nephrology & Hypertension, Oregon Health & Science University, & VA Medical Center, Portland, Oregon, United States
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Ellison DH, Terker AS. Why Your Mother Was Right: How Potassium Intake Reduces Blood Pressure. TRANSACTIONS OF THE AMERICAN CLINICAL AND CLIMATOLOGICAL ASSOCIATION 2015; 126:46-55. [PMID: 26330658 PMCID: PMC4530669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Low potassium intake, common in western diets, increases blood pressure and enhances salt-sensitivity. Most humans in "Westernized" countries also consume excess salt. In studies using mice, we found that a high-salt, low-potassium diet activates the thiazide-sensitive Na-Cl cotransporter in the kidney. This effect led to sodium retention and increased blood pressure, and was dependent on plasma potassium. We postulated that this effect was mediated by changes in intracellular chloride caused by changes in membrane voltage. We developed a model in cultured cells permitting us to confirm this hypothesis. We then confirmed, using urinary exosomes, that dietary changes in normal humans, affect the thiazide-sensitive Na-Cl cotransporter in the same way. These data show that dietary potassium deficiency increases blood pressure largely by stimulating salt reabsorption along the distal nephron. They suggest that global efforts should focus on increasing potassium intake, which will attenuate the effects of high-salt diets.
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Affiliation(s)
- David H. Ellison
- Correspondence and reprint requests: David H. Ellison, MD,
Division of Nephrology & Hypertension, CH12R, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239503-494-4465503-494-5330
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65
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Soleimani M. The multiple roles of pendrin in the kidney. Nephrol Dial Transplant 2014; 30:1257-66. [PMID: 25281699 DOI: 10.1093/ndt/gfu307] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 08/25/2014] [Indexed: 12/30/2022] Open
Abstract
The [Formula: see text] exchanger pendrin (SLC26A4, PDS) is located on the apical membrane of B-intercalated cells in the kidney cortical collecting duct and the connecting tubules and mediates the secretion of bicarbonate and the reabsorption of chloride. Given its dual function of bicarbonate secretion and chloride reabsorption in the distal tubules, it was thought that pendrin plays important roles in systemic acid-base balance and electrolyte and vascular volume homeostasis under basal conditions. Mice with the genetic deletion of pendrin or humans with inactivating mutations in PDS gene, however, do not display excessive salt and fluid wasting or altered blood pressure under baseline conditions. Very recent reports have unmasked the basis of incongruity between the mild phenotype in mutant mice and the role of pendrin as an important player in salt reabsorption in the distal tubule. These studies demonstrate that pendrin and the Na-Cl cotransporter (NCC; SLC12A3) cross compensate for the loss of each other, therefore masking the role that each transporter plays in salt reabsorption under baseline conditions. In addition, pendrin regulates calcium reabsorption in the distal tubules. Furthermore, combined deletion of pendrin and NCC not only causes severe volume depletion but also results in profound calcium wasting and luminal calcification in medullary collecting ducts. Based on studies in pathophysiological states and the examination of genetically engineered mouse models, the evolving picture points to important roles for pendrin (SLC26A4) in kidney physiology and in disease states. This review summarizes recent advances in the characterization of pendrin and the multiple roles it plays in the kidney, with emphasis on its essential roles in several diverse physiological processes, including chloride homeostasis, vascular volume and blood pressure regulation, calcium excretion and kidney stone formation.
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Affiliation(s)
- Manoocher Soleimani
- Center on Genetics of Transport and Epithelial Biology, University of Cincinnati, Cincinnati, OH, USA Research Services, Veterans Affairs Medical Center, Cincinnati, OH, USA Department of Medicine, University of Cincinnati, Cincinnati, OH, USA
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Todkar A, Picard N, Loffing-Cueni D, Sorensen MV, Mihailova M, Nesterov V, Makhanova N, Korbmacher C, Wagner CA, Loffing J. Mechanisms of renal control of potassium homeostasis in complete aldosterone deficiency. J Am Soc Nephrol 2014; 26:425-38. [PMID: 25071088 DOI: 10.1681/asn.2013111156] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Aldosterone-independent mechanisms may contribute to K(+) homeostasis. We studied aldosterone synthase knockout (AS(-/-)) mice to define renal control mechanisms of K(+) homeostasis in complete aldosterone deficiency. AS(-/-) mice were normokalemic and tolerated a physiologic dietary K(+) load (2% K(+), 2 days) without signs of illness, except some degree of polyuria. With supraphysiologic K(+) intake (5% K(+)), AS(-/-) mice decompensated and became hyperkalemic. High-K(+) diets induced upregulation of the renal outer medullary K(+) channel in AS(-/-) mice, whereas upregulation of the epithelial sodium channel (ENaC) sufficient to increase the electrochemical driving force for K(+) excretion was detected only with a 2% K(+) diet. Phosphorylation of the thiazide-sensitive NaCl cotransporter was consistently lower in AS(-/-) mice than in AS(+/+) mice and was downregulated in mice of both genotypes in response to increased K(+) intake. Inhibition of the angiotensin II type 1 receptor reduced renal creatinine clearance and apical ENaC localization, and caused severe hyperkalemia in AS(-/-) mice. In contrast with the kidney, the distal colon of AS(-/-) mice did not respond to dietary K(+) loading, as indicated by Ussing-type chamber experiments. Thus, renal adaptation to a physiologic, but not supraphysiologic, K(+) load can be achieved in aldosterone deficiency by aldosterone-independent activation of the renal outer medullary K(+) channel and ENaC, to which angiotensin II may contribute. Enhanced urinary flow and reduced activity of the thiazide-sensitive NaCl cotransporter may support renal adaptation by activation of flow-dependent K(+) secretion and increased intratubular availability of Na(+) that can be reabsorbed in exchange for K(+) secreted.
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Affiliation(s)
- Abhijeet Todkar
- Institutes of Anatomy and Physiology, and Zurich Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | | | | | | | | | - Viatcheslav Nesterov
- Institute for Cellular and Molecular Physiology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany; and
| | - Natalia Makhanova
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina
| | - Christoph Korbmacher
- Institute for Cellular and Molecular Physiology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany; and
| | - Carsten A Wagner
- Physiology, and Zurich Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Johannes Loffing
- Institutes of Anatomy and Zurich Center of Integrative Human Physiology, University of Zurich, Zurich, Switzerland;
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