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Porter A, Vorndran HE, Marciszyn A, Mutchler SM, Subramanya AR, Kleyman TR, Hendershot LM, Brodsky JL, Buck TM. Excess dietary sodium partially restores salt and water homeostasis caused by loss of the endoplasmic reticulum molecular chaperone, GRP170, in the mouse nephron. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.13.575426. [PMID: 38260467 PMCID: PMC10802592 DOI: 10.1101/2024.01.13.575426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The maintenance of fluid and electrolyte homeostasis by the kidney requires proper folding and trafficking of ion channels and transporters in kidney epithelia. Each of these processes requires a specific subset of a diverse class of proteins termed molecular chaperones. One such chaperone is GRP170, which is an Hsp70-like, endoplasmic reticulum (ER)-localized chaperone that plays roles in protein quality control and protein folding in the ER. We previously determined that loss of GRP170 in the mouse nephron leads to hypovolemia, electrolyte imbalance, and rapid weight loss. In addition, GRP170-deficient mice develop an AKI-like phenotype, typified by tubular injury, elevation of clinical kidney injury markers, and induction of the unfolded protein response (UPR). By using an inducible GRP170 knockout cellular model, we confirmed that GRP170 depletion induces the UPR, triggers an apoptotic response, and disrupts protein homeostasis. Based on these data, we hypothesized that UPR induction underlies hyponatremia and volume depletion in rodents, but that these and other phenotypes might be rectified by supplementation with high salt. To test this hypothesis, control and GRP170 tubule-specific knockout mice were provided with a diet containing 8% sodium chloride. We discovered that sodium supplementation improved electrolyte imbalance and reduced clinical kidney injury markers, but was unable to restore weight or tubule integrity. These results are consistent with UPR induction contributing to the kidney injury phenotype in the nephron-specific GR170 knockout model, and that the role of GRP170 in kidney epithelia is essential to both maintain electrolyte balance and cellular protein homeostasis.
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Affiliation(s)
- Aidan Porter
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
- Division of Pediatric Nephrology, University of Pittsburgh, Pittsburgh, PA
| | - Hannah E. Vorndran
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Allison Marciszyn
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, PA
| | - Stephanie M. Mutchler
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, PA
| | - Arohan R. Subramanya
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, PA
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA
| | - Thomas R. Kleyman
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, PA
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA
| | - Linda M. Hendershot
- Department of Tumor Cell Biology, St. Jude Children’s Research Hospital, Memphis, TN 30105
| | - Jeffrey L. Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Teresa M. Buck
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
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Affiliation(s)
- Horacio J Adrogué
- From the Department of Medicine, Section of Nephrology, Baylor College of Medicine, and the Department of Medicine, Division of Nephrology, Houston Methodist Hospital - both in Houston (H.J.A.); and the Department of Medicine, Tufts University School of Medicine, and the Department of Medicine, Division of Nephrology, St. Elizabeth's Medical Center - both in Boston (N.E.M.)
| | - Nicolaos E Madias
- From the Department of Medicine, Section of Nephrology, Baylor College of Medicine, and the Department of Medicine, Division of Nephrology, Houston Methodist Hospital - both in Houston (H.J.A.); and the Department of Medicine, Tufts University School of Medicine, and the Department of Medicine, Division of Nephrology, St. Elizabeth's Medical Center - both in Boston (N.E.M.)
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Tang H, Xu C, Zhang P, Luo T, Huang Y, Yang X. A profile of SGLT-2 inhibitors in hyponatremia: The evidence to date. Eur J Pharm Sci 2023; 184:106415. [PMID: 36870579 DOI: 10.1016/j.ejps.2023.106415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 02/14/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023]
Abstract
Hyponatremia is the most common electrolyte disorder in clinical practice, which may lead to life-threatening complications. Several lines of evidence suggest that hyponatremia is associated not only with significant increases in length of stay, cost, and financial burden, but also with increased morbidity and mortality. Hyponatremia is also considered to be a negative prognostic factor in patients with heart failure and cancer. Although multiple therapeutic methods are available for treating hyponatremia, most have some limitations, such as poor compliance, rapid correction of serum Na+, other negative side effects and high cost. Given these limitations, identifying novel therapies for hyponatremia is essential. Recent clinical studies have shown that SGLT-2 inhibitors (SGLT 2i) significantly increased serum Na+ levels and were well tolerated by patients who underwent this treatment. Therefore, oral administration of SGLT 2i appears to be an effective treatment for hyponatremia. This article will briefly review the etiology of hyponatremia and integrated control of sodium within the kidney, current therapies for hyponatremia, potential mechanisms and efficacy of SGLT 2i for hyponatremia, and the benefits in cardiovascular, cancer, and kidney disease by regulating sodium and water balance.
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Affiliation(s)
- Hui Tang
- Department of Pharmacy, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China; School of Pharmacy, Southwest Medical University, Luzhou 646000, China
| | - Changjing Xu
- Department of Pharmacy, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China
| | - Piao Zhang
- Department of Pharmacy, Ya 'an People's Hospital, Ya 'an, Sichuan 646000, China
| | - Taimin Luo
- Department of pharmacy, Chengdu Seventh People's Hospital, Chengdu, Sichuan 610000, China
| | - Yilan Huang
- Department of Pharmacy, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China; School of Pharmacy, Southwest Medical University, Luzhou 646000, China.
| | - Xuping Yang
- Department of Pharmacy, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China; School of Pharmacy, Southwest Medical University, Luzhou 646000, China.
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Kamel MH, Upadhyay A, Borkan SC. Intractable hyponatremia complicated by a reset osmostat: a case report. J Med Case Rep 2023; 17:13. [PMID: 36639685 PMCID: PMC9840259 DOI: 10.1186/s13256-022-03732-w] [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: 04/21/2021] [Accepted: 12/21/2022] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Hyponatremia associated with a low serum osmolality is a common and confounding electrolyte disorder. Correcting hyponatremia is also complicated, especially in the setting of chronic hyponatremia. Here, we provide a rational approach to accurately detecting and safely treating acute on chronic euvolemic hyponatremia in the setting of acute polydipsia with a chronic reset osmostat. CASE PRESENTATION A 71-year-old hispanic gentleman with chronic hyponatremia presented with hiccups, polydipsia, and a serum sodium concentration of 120 mEq/L associated with diffuse weakness, inattentiveness, and suicidal ideation. Symptomatic euvolemic hyponatremia warranted hypertonic saline treatment in the acute phase and water restriction in the chronic phase. Both interventions resulted in improvement in symptoms and/or the serum sodium concentration, but to a serum sodium level that persistently remained below the normal range. Remarkably, the urine osmolality appropriately fell when the serum sodium concentration fell below 126 mEq/L. Also remarkable was the appropriate increase in urine osmolality when the serum sodium concentration exceeded 126 mEq/L. The preservation of both concentration and dilution, albeit at a lower-than-normal serum osmolality, shows that the osmostat regulating antidiuretic hormone release had been "reset." Both physiologic and pharmacologic resetting of the osmostat are discussed. CONCLUSIONS Preservation of urinary concentrating and diluting ability at a lower-than-normal serum sodium concentration, especially in the setting of chronic hyponatremia, is diagnostic of a reset osmostat. The presence of a reset osmostat often confounds the treatment of concomitant acute hyponatremia. Early recognition of a reset osmostat avoids the need to normalize serum sodium concentration, expedites hospital discharge, and limits potential harm from overcorrecting acute hyponatremia.
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Affiliation(s)
- Mohamed Hassan Kamel
- grid.189504.10000 0004 1936 7558Section of Nephrology, Department of Medicine, Boston Medical Center and Boston University School of Medicine, Boston, MA USA
| | - Ashish Upadhyay
- grid.189504.10000 0004 1936 7558Section of Nephrology, Department of Medicine, Boston Medical Center and Boston University School of Medicine, Boston, MA USA
| | - Steven C. Borkan
- grid.189504.10000 0004 1936 7558Section of Nephrology, Department of Medicine, Boston Medical Center and Boston University School of Medicine, Boston, MA USA ,Evans Biomedical Research Center, 650 Albany St, Room 546, Boston, MA 02118-2518 USA
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Baba M, Alsbrook D, Williamson S, Soman S, Ramadan AR. Approach to the Management of Sodium Disorders in the Neuro Critical Care Unit. Curr Treat Options Neurol 2022. [DOI: 10.1007/s11940-022-00723-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Workeneh BT, Jhaveri KD, Rondon-Berrios H. Hyponatremia in the cancer patient. Kidney Int 2020; 98:870-882. [DOI: 10.1016/j.kint.2020.05.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/28/2020] [Accepted: 05/11/2020] [Indexed: 02/08/2023]
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