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Chrysant SG. The Interaction of Kidneys and Gut in Development of Salt-Sensitive Hypertension. Cardiol Rev 2024; 32:356-361. [PMID: 37273192 DOI: 10.1097/crd.0000000000000518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The incidence of salt-sensitive hypertension is quite common and varies between 30-60% in hypertensive patients. Regarding the causal role of high salt intake in the development of salt-sensitive hypertension, recent evidence has demonstrated that the gut through its microbiota plays a significant role in its genesis. Besides the gut, the kidneys also play important role in salt-sensitive hypertension and there is clinical and experimental evidence of an interrelationship between the gut and the kidneys in the development of salt-sensitive hypertension through the so-called "gastro-renal axis." The gut besides being an absorptive organ, it is also a hormonal secretory organ involving the secretion of gastrin, dopamine, norepinephrine, angiotensin, and aldosterone which through their action with the kidneys are involved in the development of salt-sensitive hypertension. In addition, the kidneys exert a protective role against the development of hypertension through the secretion of prostaglandins and their vasodilatory action. To assess the current evidence on the role of high salt intake and the interplay of the gut and kidneys in its development, a Medline search of the English literature was contacted between 2012 and 2022, and 46 pertinent papers were selected. These papers together with collateral literature will be discussed in this review.
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Affiliation(s)
- Steven G Chrysant
- From the University of Oklahoma Health Sciences Center, Oklahoma City, OK
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Chrysant SG. The role of gut microbiota in the development of salt-sensitive hypertension and the possible preventive effect of exercise. Expert Rev Cardiovasc Ther 2024; 22:265-271. [PMID: 38823009 DOI: 10.1080/14779072.2024.2364031] [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: 10/31/2023] [Accepted: 05/31/2024] [Indexed: 06/03/2024]
Abstract
INTRODUCTION The aim of the present study is to analyze the data indicating an association between high salt intake and the gastrointestinal microbiota in the development of salt-sensitive hypertension in animals and men. It is also, to discuss the preventive effects of exercise on gut-induced hypertension by favorably modifying the composition of gut microbiota. AREAS COVERED Salt sensitivity is quite common, accounting for 30%-60% in hypertensive subjects. Recently, a novel cause for salt-sensitive hypertension has been discovered through the action of gut microbiota by the secretion of several hormones and the action of short chain fatty acids (SCFAs). In addition, recent studies indicate that exercise might favorably modify the adverse effects of gut microbiota regarding their effects on BP. To identify the role of gut microbiota on the incidence of hypertension and CVD and the beneficial effect of exercise, a Medline search of the English literature was conducted between 2018 and 2023 and 42 pertinent papers were selected. EXPERT OPINION The analysis of data from the selected papers disclosed that the gut microbiota contribute significantly to the development of salt-sensitive hypertension and that exercise modifies their gut composition and ameliorates their adverse effects on BP.
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Affiliation(s)
- Steven G Chrysant
- Cardiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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Colonic Fluid and Electrolyte Transport 2022: An Update. Cells 2022; 11:cells11101712. [PMID: 35626748 PMCID: PMC9139964 DOI: 10.3390/cells11101712] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 05/16/2022] [Accepted: 05/17/2022] [Indexed: 01/25/2023] Open
Abstract
Colonic epithelial cells are responsible for maintaining a delicate balance between luminal secretion and the absorption of fluids and ions. This review aims to discuss and update the model of colonic electrolyte secretion and absorption via the cystic fibrosis transmembrane regulator (CFTR), epithelial sodium channel (ENaC), Na-K-Cl cotransporters (NKCC1 and 2), Na-H exchangers (NHE1–4), colonic H,KATPase, and several other key components involved in multi-level transepithelial ion transport. Developments in our understanding of the activity, regulation, localization, and relationships of these ion transporters and their interactions have helped forge a more robust understanding of colonic ion movement that accounts for the colonic epithelium’s role in mucosal pH modulation, the setting of osmotic gradients pivotal for fluid retention and secretion, and cell death regulation. Deviations from homeostatic ion transport cause diarrhea, constipation, and epithelial cell death and contribute to cystic fibrosis, irritable bowel syndrome (IBS), ulcerative colitis, and cancer pathologies. Signal transduction pathways that regulate electrolyte movement and the regulatory relationships between various sensors and transporters (CFTR as a target of CaSR regulation and as a regulator of ENaC and DRA, for example) are imperative aspects of a dynamic and comprehensive model of colonic ion homeostasis.
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Ryuzaki M, Miyashita K, Sato M, Inoue H, Fujii K, Hagiwara A, Uto A, Endo S, Oshida T, Kinouchi K, Itoh H. Activation of the intestinal tissue renin-angiotensin system by transient sodium loading in salt-sensitive rats. J Hypertens 2022; 40:33-45. [PMID: 34285148 PMCID: PMC8654260 DOI: 10.1097/hjh.0000000000002974] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 06/14/2021] [Accepted: 07/04/2021] [Indexed: 11/25/2022]
Abstract
BACKGROUND The renal tissue renin-angiotensin system is known to be activated by salt loading in salt-sensitive rats; however, the response in other organs remains unclear. METHOD Spontaneously hypertensive rats were subjected to normal tap water or transient high-salt-concentration water from 6 to 14 weeks of age and were thereafter given normal tap water. From 18 to 20 weeks of age, rats given water with a high salt concentration were treated with an angiotensin II type 1 receptor blocker, valsartan. RESULTS Sustained blood pressure elevation by transient salt loading coincided with a persistent decrease in the fecal sodium content and sustained excess of the circulating volume in spontaneously hypertensive rats. Administration of valsartan sustainably reduced the blood pressure and normalized the fecal sodium levels. Notably, transient salt loading persistently induced the intestinal tissue renin-angiotensin system and enhanced sodium transporter expression exclusively in the small intestine of salt-sensitive rats, suggesting the potential connection of intestinal sodium absorption to salt sensitivity. CONCLUSION These results reveal the previously unappreciated contribution of the intestinal tissue renin-angiotensin system to sodium homeostasis and blood pressure regulation in the pathophysiology of salt-sensitive hypertension.
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Affiliation(s)
- Masaki Ryuzaki
- Division of Endocrinology, Metabolism, and Nephrology, Department of Internal Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
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Linz B, Hohl M, Mishima R, Saljic A, Lau DH, Jespersen T, Schotten U, Sanders P, Linz D. Pharmacological inhibition of sodium-proton-exchanger subtype 3-mediated sodium absorption in the gut reduces atrial fibrillation susceptibility in obese spontaneously hypertensive rats. IJC HEART & VASCULATURE 2020; 28:100534. [PMID: 32462076 PMCID: PMC7243186 DOI: 10.1016/j.ijcha.2020.100534] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/19/2020] [Accepted: 05/05/2020] [Indexed: 01/25/2023]
Abstract
BACKGROUND Increased sodium uptake has been shown to contribute to hypertension and cardiac end-organ damage. The sodium-proton-exchanger subtype 3 (NHE3) is an important mediator of intestinal sodium absorption. Whether a reduction in intestinal sodium absorption can prevent the development of an atrial arrhythmogenic substrate in hypertension is unknown. METHODS Eight-week-old obese spontaneously hypertensive rats (SHR-ob) were treated for six weeks with the gut-specific NHE3-inhibitor SAR (1-(β-D-glucopyranosyl)-3-{3-[(4S)-6,8-dichloro-2-methyl-1,2,3,4-tetrahydroiso-chinolin-4-yl]phenyl}urea, 1 mg/kg/d in chow, SHR-ob SAR, n = 7) and compared to aged-matched placebo-treated SHR-ob (SHR-ob PLAC, n = 8). Cardiac magnetic resonance imaging was performed at the end of the treatment period to assess atrial emptying function. Afterwards, local conduction disturbances and inducible atrial fibrillation (AF) duration were determined and histological analysis to quantify atrial fibrosis amount were performed. RESULTS Inhibition of intestinal NHE3 by SAR increased fecal sodium excretion, resulted in marked changes in feces electrolyte concentrations and water content, reduced blood pressure and preserved atrial emptying function (active total percent emptying: SHR-ob SAR: 0.47 ± 0.05% vs. SHR-ob PLAC: 0.38 ± 0.007, p < 0.0001). Atrial fibrosis content was lower (21.4 ± 2.5% vs. 36.7 ± 1.2%, p < 0.0001) and areas of slow conduction were smaller (2.5 ± 0.09% vs. 5.3 ± 0.2%, p < 0.0001) in SHR-ob SAR compared to SHR-ob PLAC. Left atrial burst stimulation resulted in shorter inducible AF-durations in SHR-ob SAR compared to SHR-ob PLAC. CONCLUSIONS Reduction of intestinal sodium absorption and subsequent changes in feces milieu by pharmacological NHE3 inhibition in the gut preserved atrial emptying function and reduced AF susceptibility. Whether pharmacological NHE3 inhibition in the gut prevents AF in humans warrants further study.
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Affiliation(s)
- Benedikt Linz
- Klinik für Innere Medizin III, Universität des Saarlandes, 66421 Homburg/Saar, Germany
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mathias Hohl
- Klinik für Innere Medizin III, Universität des Saarlandes, 66421 Homburg/Saar, Germany
| | - Ricardo Mishima
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, Royal Adelaide Hospital, University of Adelaide, Adelaide, Australia
| | - Arnela Saljic
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Dennis H. Lau
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, Royal Adelaide Hospital, University of Adelaide, Adelaide, Australia
| | - Thomas Jespersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ulrich Schotten
- University Maastricht, Cardiovascular Research Institute Maastricht (CARIM), the Netherlands
| | - Prashanthan Sanders
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, Royal Adelaide Hospital, University of Adelaide, Adelaide, Australia
| | - Dominik Linz
- Klinik für Innere Medizin III, Universität des Saarlandes, 66421 Homburg/Saar, Germany
- Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, Royal Adelaide Hospital, University of Adelaide, Adelaide, Australia
- University Maastricht, Cardiovascular Research Institute Maastricht (CARIM), the Netherlands
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Abstract
Purpose of Review The purpose of this review is to summarize the most recent data available on advances in development of novel medical treatments for hypertension and related comorbidities. Recent Findings Approximately half of all hypertensive patients have not achieved goal blood pressure with current available antihypertensive medications. Recent landmark studies and new hypertension guidelines have called for stricter blood pressure control, creating a need for better strategies for lowering blood pressure. This has led to a shift in focus, in recent years, to the development of combination pills as a means of achieving improved blood pressure control by increasing adherence to prescribed medications along with further research and development of promising novel drugs based on discovery of new molecular targets such as the counter-regulatory renin-angiotensin system. Summary Fixed-dose combination pills and novel treatments based on recently discovered pathogenic mechanisms of hypertension that have demonstrated promising results as treatments for hypertension and related comorbidities will be discussed in this review.
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Affiliation(s)
- Jared Davis
- Department of Medicine, University of Alabama at Birmingham, BDB 327, 1720 2nd Ave S, Birmingham, AL, 35294, USA.
| | - Suzanne Oparil
- UAB Vascular Biology and Hypertension Program, Division of Cardiovascular Disease, University of Alabama at Birmingham, ZRB 1034, 703 19th St S, Birmingham, AL, 35233, USA
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Rosenbaum DP, Yan A, Jacobs JW. Pharmacodynamics, Safety, and Tolerability of the NHE3 Inhibitor Tenapanor: Two Trials in Healthy Volunteers. Clin Drug Investig 2018; 38:341-351. [PMID: 29363027 PMCID: PMC5856883 DOI: 10.1007/s40261-017-0614-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Background Tenapanor, a small molecule with minimal systemic availability, is a first-in-class sodium/hydrogen exchanger 3 (NHE3) inhibitor that acts in the gut. Here, we evaluate the pharmacodynamics and safety of tenapanor in healthy adults. Methods Two phase I, single-center, randomized, double-blind, placebo-controlled studies were performed. The first study assessed single-ascending oral tenapanor doses of 10, 50, 150, 450, and 900 mg (n = 8 per group; six tenapanor, two placebo) and multiple ascending doses over 7 days of 3, 10, 30, and 100 mg q.d. (n = 10 per group; eight tenapanor, two placebo). In the second study, different tenapanor regimens were evaluated over 7 days (n = 15 per group; 12 tenapanor, three placebo): 15 mg twice daily (b.i.d.), 30 mg once daily (q.d.), 30 mg b.i.d., 30 mg three times daily (t.i.d.), 60 mg b.i.d., escalating b.i.d. dose (daily total 30–90 mg), 30 mg b.i.d. with psyllium. Results Tenapanor produced generally dose-dependent increases in stool sodium excretion and decreases in urinary sodium excretion versus placebo; in addition, twice-daily dosing appeared to have a greater effect on sodium absorption than once-daily dosing with an equivalent daily dose. Tenapanor softened stool consistency and increased stool frequency and weight from baseline versus placebo. Tenapanor concentrations were below the quantification limit (0.5 ng/ml) in 98.5% of 895 plasma samples. Adverse events were mild or moderate in severity, and were typically gastrointestinal in nature. There were no clinically relevant changes in serum electrolytes. Conclusions Tenapanor was well tolerated and resulted in reduced intestinal sodium absorption and softer stool consistency versus placebo. Systemic exposure to tenapanor was minimal. These results support potential use of tenapanor in patients who could benefit from modification of gastrointestinal sodium balance. ClinicalTrials.gov identifiers NCT02819687, NCT02796131. Electronic supplementary material The online version of this article (10.1007/s40261-017-0614-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- David P Rosenbaum
- Ardelyx Inc., 34175 Ardenwood Blvd, Suite 200, Fremont, CA, 94555, USA.
| | - Andrew Yan
- Ardelyx Inc., 34175 Ardenwood Blvd, Suite 200, Fremont, CA, 94555, USA
| | - Jeffrey W Jacobs
- Ardelyx Inc., 34175 Ardenwood Blvd, Suite 200, Fremont, CA, 94555, USA
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Wei X, Lu Z, Yang T, Gao P, Chen S, Liu D, Zhu Z. Stimulation of Intestinal Cl- Secretion Through CFTR by Caffeine Intake in Salt-Sensitive Hypertensive Rats. Kidney Blood Press Res 2018; 43:439-448. [DOI: 10.1159/000488256] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 03/09/2018] [Indexed: 11/19/2022] Open
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Sircana A, De Michieli F, Parente R, Framarin L, Leone N, Berrutti M, Paschetta E, Bongiovanni D, Musso G. Gut microbiota, hypertension and chronic kidney disease: Recent advances. Pharmacol Res 2018; 144:390-408. [PMID: 29378252 DOI: 10.1016/j.phrs.2018.01.013] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 12/29/2017] [Accepted: 01/22/2018] [Indexed: 02/07/2023]
Abstract
A large number of different microbial species populates intestine. Extensive research has studied the entire microbial population and their genes (microbiome) by using metagenomics, metatranscriptomics and metabolomic analysis. Studies suggest that the imbalances of the microbial community causes alterations in the intestinal homeostasis, leading to repercussions on other systems: metabolic, nervous, cardiovascular, immune. These studies have also shown that alterations in the structure and function of the gut microbiota play a key role in the pathogenesis and complications of Hypertension (HTN) and Chronic Kidney Disease (CKD). Increased blood pressure (BP) and CKD are two leading risk factors for cardiovascular disease and their treatment represents a challenge for the clinicians. In this Review, we discuss mechanisms whereby gut microbiota (GM) and its metabolites act on downstream cellular targets to contribute to the pathogenesis of HTN and CKD, and potential therapeutic implications.
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Affiliation(s)
- Antonio Sircana
- Unità Operativa di Cardiologia, Azienda Ospedaliero Universitaria, Sassari, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Franco De Michieli
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Renato Parente
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Luciana Framarin
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Nicola Leone
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Mara Berrutti
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Elena Paschetta
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Daria Bongiovanni
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Giovanni Musso
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy.
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Abstract
PURPOSE OF REVIEW This review focuses on recent advances in our understanding of intradialytic hypotension (IDH) and measures that may reduce its frequency. RECENT FINDINGS The frequency and severity of IDH predict the risk for adverse clinical outcomes. The highest mortality risks associated with IDH were observed when the intradialytic systolic blood pressure (SBP) nadirs were <90 and <100 mmHg and the predialysis SBP were ≤159 mmHg or ≥160 mmHg, respectively. Interdialytic weight gain (IDWG) ≥3 kg occurs more frequently among patients with IDH. Prolonged and possibly more frequent dialysis, use of biofeedback devices, dialysate cooling and limiting sodium loading are useful measures to reduce the frequency of IDH. SUMMARY Frequent IDH is associated with high IDWGs and a poor prognosis. Studies on prolonged dialysis, biofeedback devices and cooled dialysate have yielded promising results. Intradialytic relative blood volume monitoring devices have been investigated in preventing IDH but results are mixed. Administration of a sodium/hydrogen exchange isoform 3 inhibitor increases stool sodium but has not been shown to decrease IDWG. IDH continues to be a significant dialysis complication deserving of further investigation.
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Abstract
Fierce debate has developed whether low-sodium intake, like high-sodium intake, could be associated with adverse outcome. The debate originates in earlier epidemiological studies associating high-sodium intake with high blood pressure and more recent studies demonstrating a higher cardiovascular event rate with both low- and high-sodium intake. This brings into question whether we entirely understand the consequences of high- and (very) low-sodium intake for the systemic hemodynamics, the kidney function, the vascular wall, the immune system, and the brain. Evolutionarily, sodium retention mechanisms in the context of low dietary sodium provided a survival advantage and are highly conserved, exemplified by the renin-angiotensin system. What is the potential for this sodium-retaining mechanism to cause harm? In this paper, we will consider current views on how a sodium load is handled, visiting aspects including the effect of sodium on the vessel wall, the sympathetic nervous system, the brain renin-angiotensin system, the skin as "third compartment" coupling to vascular endothelial growth factor C, and the kidneys. From these perspectives, several mechanisms can be envisioned whereby a low-sodium diet could potentially cause harm, including the renin-angiotensin system and the sympathetic nervous system. Altogether, the uncertainties preclude a unifying model or practical clinical guidance regarding the effects of a low-sodium diet for an individual. There is a very strong need for fundamental and translational studies to enhance the understanding of the potential adverse consequences of low-salt intake as an initial step to facilitate better clinical guidance.
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Affiliation(s)
- Branko Braam
- Department of Medicine, University of Alberta, Edmonton, AB, Canada. .,Department of Physiology, University of Alberta, Edmonton, AB, Canada. .,Department of Medicine / Division of Nephrology and Immunology, University of Alberta Hospital, 11-132 CSB Clinical Sciences Building, Edmonton, AB, T6G 2G3, Canada.
| | - Xiaohua Huang
- Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - William A Cupples
- Biomedical Physiology & Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Shereen M Hamza
- Department of Medicine, University of Alberta, Edmonton, AB, Canada.,Department of Physiology, University of Alberta, Edmonton, AB, Canada
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Visconti L, Cernaro V, Calimeri S, Lacquaniti A, De Gregorio F, Ricciardi CA, Lacava V, Santoro D, Buemi M. The Myth of Water and Salt: From Aquaretics to Tenapanor. J Ren Nutr 2017; 28:73-82. [PMID: 29146141 DOI: 10.1053/j.jrn.2017.06.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 05/13/2017] [Accepted: 06/09/2017] [Indexed: 12/21/2022] Open
Abstract
The impact of water intake has been studied in several renal diseases. For example, increasing water intake is useful to prevent primary and secondary nephrolithiasis. In autosomal dominant polycystic kidney disease, arginine vasopressin (AVP) is involved in the progression of the disease, and water intake could play a therapeutic role by inhibiting the synthesis of AVP, but its efficacy is still controversial. Conversely, the use of aquaretics, which are antagonists of AVP V2 receptors, results in the reduction of the increase rate of total kidney volume with a slower decline of glomerular filtration rate. In chronic kidney disease, AVP contributes to glomerular hyperfiltration, arterial hypertension, and synthesis of renin, resulting in renal sclerosis. Increased water intake could reduce AVP activation determining a potential protective effect on the kidney, but its efficacy has not yet been clearly demonstrated. On the other side, sodium and potassium play an important role in the control of arterial blood pressure and are involved in the development and progression of chronic kidney disease. Reduction of sodium intake and increase of potassium intake determine a decrease of arterial blood pressure with a beneficial effect on the kidney; however, adherence to sodium restriction is very poor. Regarding this, sodium-hydrogen exchanger isoform 3 inhibitors may reduce sodium absorption in the gut. The most recent sodium-hydrogen exchanger isoform 3 inhibitor, known as tenapanor, reduces extracellular fluid volume, left ventricular hypertrophy, albuminuria, and blood pressure in experimental studies and increases fecal loss of sodium in humans.
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Affiliation(s)
- Luca Visconti
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy.
| | - Valeria Cernaro
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Sebastiano Calimeri
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Antonio Lacquaniti
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Francesca De Gregorio
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | | | - Viviana Lacava
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Domenico Santoro
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Michele Buemi
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
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Yin J, Tse CM, Cha B, Sarker R, Zhu XC, Walentinsson A, Greasley PJ, Donowitz M. A common NHE3 single-nucleotide polymorphism has normal function and sensitivity to regulatory ligands. Am J Physiol Gastrointest Liver Physiol 2017; 313:G129-G137. [PMID: 28495802 PMCID: PMC5582881 DOI: 10.1152/ajpgi.00044.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 05/01/2017] [Accepted: 05/05/2017] [Indexed: 01/31/2023]
Abstract
Na+/H+ exchanger NHE3 mediates the majority of intestinal and renal electroneutral sodium absorption. Dysfunction of NHE3 is associated with a variety of diarrheal diseases. We previously reported that the NHE3 gene (SLC9A3) has more than 400 single-nucleotide polymorphisms (SNPs) but few nonsynonymous polymorphisms. Among the latter, one polymorphism (rs2247114-G>A), which causes a substitution from arginine to cysteine at amino acid position 799 (p.R799C), is common in Asian populations. To improve our understanding of the population distribution and potential clinical significance of the NHE3-799C variant, we investigated the frequency of this polymorphism in different ethnic groups using bioinformatics analyses and in a cohort of Japanese patients with cardiovascular or renal disease. We also characterized the function of human NHE3-799C and its sensitivity to regulatory ligands in an in vitro model. NHE3-799C had an allele frequency of 29.5-57.6% in Asian populations, 11.1-23.6% in European populations, and 10.2-22.7% in African populations. PS120/FLAG-NHERF2 fibroblasts stably expressing NHE3-799C had lower total protein expression but a higher percentage of surface expression than those expressing NHE3-799R. NHE3-799C had similar basal activity to NHE3-799R and was similarly stimulated or inhibited, by serum or forskolin, respectively. Tenapanor, a small-molecule NHE3 inhibitor, dose-dependently inhibited NHE3-799R and NHE3-799C activities. The IC50 values of tenapanor for NHE3-799C and NHE3-799R were significantly different, but both were in the nanomolar range. These results suggest that NHE3-799C is a common variant enriched in Asian populations, is not associated with compromised function or abnormal regulation, and is unlikely to contribute to clinical disease.NEW & NOTEWORTHY This study reports results on the functional significance of human NHE3-799C under basal conditions and in response to regulatory ligands, including a novel NHE3 inhibitor called tenapanor. We demonstrate that NHE3-799C is a common variant of NHE3 that is enriched in Asian populations; however, in contrast to our previous studies using rabbit NHE3, its presence seems to have limited clinical significance in humans and is not associated with compromised function or abnormal transport regulation.
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Affiliation(s)
- Jianyi Yin
- 1Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Chung-Ming Tse
- 1Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Boyoung Cha
- 1Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Rafiquel Sarker
- 1Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Xinjun C. Zhu
- 2Department of Medicine, Division of Gastroenterology and Hepatology, Albany Medical College, Albany, New York; and
| | | | | | - Mark Donowitz
- Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
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Johansson SA, Knutsson M, Leonsson‐Zachrisson M, Rosenbaum DP. Effect of Food Intake on the Pharmacodynamics of Tenapanor: A Phase 1 Study. Clin Pharmacol Drug Dev 2017; 6:457-465. [PMID: 28339149 PMCID: PMC5599956 DOI: 10.1002/cpdd.341] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 01/18/2017] [Indexed: 01/10/2023]
Abstract
Tenapanor (RDX5791/AZD1722) is a minimally systemic small-molecule inhibitor of the sodium/hydrogen exchanger NHE3. Tenapanor acts in the gut to reduce absorption of sodium and phosphate. This phase 1 open-label, 3-way crossover study (NCT02226783) evaluated the effect of food on the pharmacodynamics of tenapanor. Eighteen volunteers completed a randomized sequence of three 4-day treatments with tenapanor hydrochloride 15 mg twice daily: before food, after food, and while fasting. Participants received a diet standardized for sodium content. Stool sodium was significantly higher with tenapanor administration before versus after food (difference, +8.8 mmol/day, P = .006) or while fasting (+11.8 mmol/day, P = .0004). Differences in urinary sodium were not significant. Stool phosphorus was not significantly different with tenapanor before versus after food and significantly higher before food versus while fasting (+4.9 mmol/day, P = .006). Urinary phosphorus was significantly lower when tenapanor was administered before (-3.9 mmol/day, P = .0005) or after food (-3.7 mmol/day, P = .0009) versus while fasting. No serious adverse events were reported. These data suggest the effect of tenapanor on sodium absorption is most pronounced when administered before meals, whereas the effect on phosphate is similar whether administered before or after meals. This may support different timings of tenapanor administration with respect to food for sodium- and phosphate-related indications.
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Afsar B, Vaziri ND, Aslan G, Tarim K, Kanbay M. Gut hormones and gut microbiota: implications for kidney function and hypertension. ACTA ACUST UNITED AC 2016; 10:954-961. [PMID: 27865823 DOI: 10.1016/j.jash.2016.10.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 10/25/2016] [Indexed: 02/07/2023]
Abstract
Increased blood pressure (BP) and chronic kidney disease are two leading risk factors for cardiovascular disease. Increased sodium intake is one of the most important risk factors for development of hypertension. Recent data have shown that gut influences kidney function and BP by variety of mechanisms. Various hormones and peptides secreted from gut such as gastrin, glucocorticoids, Glucagon-like peptide-1 impact on kidney function and BP especially influencing sodium absorption from gut. These findings stimulate scientist to find new therapeutic options such as tenapanor for treatment of hypertension by blocking sodium absorption from gut. The gastrointestinal tract is also occupied by a huge community of microbes (microbiome) that under normal condition has a symbiotic relationship with the host. Alterations in the structure and function of the gut microbiota have been shown to play a key role in the pathogenesis and complications of numerous diseases including hypertension. Based on these data, in this review, we provide a summary of the available data on the role of gut and gut microbiota in regulation of BP and kidney function.
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Affiliation(s)
- Baris Afsar
- Division of Nephrology, Department of Medicine, Konya Numune State Hospital, Konya, Turkey
| | - Nosratola D Vaziri
- Division of Nephrology and Hypertension, Department of Medicine, Schools of Medicine and Biological Science, University of California, Irvine, CA, USA
| | - Gamze Aslan
- Department of Cardiology, Koc University School of Medicine, Istanbul, Turkey
| | - Kayhan Tarim
- Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
| | - Mehmet Kanbay
- Division of Nephrology, Department of Medicine, Koc University School of Medicine, Istanbul, Turkey.
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Afsar B, Kiremit MC, Sag AA, Tarim K, Acar O, Esen T, Solak Y, Covic A, Kanbay M. The role of sodium intake in nephrolithiasis: epidemiology, pathogenesis, and future directions. Eur J Intern Med 2016; 35:16-19. [PMID: 27444735 DOI: 10.1016/j.ejim.2016.07.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/20/2016] [Accepted: 07/01/2016] [Indexed: 12/23/2022]
Abstract
The prevalence of nephrolithiasis has doubled over the last decade and the incidence in females now approaches that of males. Since dietary salt is lithogenic, a purported mechanism common to both genders is excess dietary sodium intake vis-a-vis processed and fast foods. Nephrolithiasis has far-reaching societal implications such as impact on gross domestic product due to days lost from work (stone disease commonly affects working adults), population-wide carcinogenic diagnostic and interventional radiation exposure (kidney stone disease is typically imaged with computed tomographic imaging and treated under imaging guidance and follow-up), and rising healthcare costs (surgical treatment will be indicated for a number of these patients). Therefore, primary prevention of kidney stone disease via dietary intervention is a low-cost public health initiative with massive societal implications. This primer aims to establish baseline epidemiologic and pathophysiologic principles to guide clinicians in sodium-directed primary prevention of kidney stone disease.
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Affiliation(s)
- Baris Afsar
- Division of Nephrology, Department of Medicine, Konya Numune State Hospital, Konya, Turkey
| | - Murat C Kiremit
- Department of Urology, Koc University School of Medicine, Istanbul, Turkey
| | - Alan A Sag
- Division of Interventional Radiology, Department of Radiology, Koc University School of Medicine, Istanbul, Turkey
| | - Kayhan Tarim
- Division of Nephrology, Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
| | - Omer Acar
- Department of Urology, Koc University School of Medicine, Istanbul, Turkey
| | - Tarik Esen
- Department of Urology, Koc University School of Medicine, Istanbul, Turkey
| | - Yalcin Solak
- Department of Nephrology, Sakarya Training and Research Hospital, Sakarya, Turkey
| | - Adrian Covic
- Nephrology Clinic, Dialysis and Renal Transplant Center, 'C.I. PARHON' University Hospital, and 'Grigore T. Popa' University of Medicine, Iasi, Romania
| | - Mehmet Kanbay
- Division of Nephrology, Department of Medicine, Koc University School of Medicine, Istanbul, Turkey.
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Ketteler M, Liangos O, Biggar PH. Treating hyperphosphatemia – current and advancing drugs. Expert Opin Pharmacother 2016; 17:1873-9. [DOI: 10.1080/14656566.2016.1220538] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Mosińska P, Salaga M, Fichna J. Novel investigational drugs for constipation-predominant irritable bowel syndrome: a review. Expert Opin Investig Drugs 2016; 25:275-86. [PMID: 26765585 DOI: 10.1517/13543784.2016.1142532] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
INTRODUCTION Constipation-predominant irritable bowel syndrome (IBS-C) is a functional gastrointestinal (GI) disorder with an unknown etiology. A number of the drugs tested for IBS-C have also been applied to chronic constipation and chronic idiopathic constipation. Unfortunately, due to severe adverse effects, many drugs envisioned for IBS-C had been withdrawn from the market. Nevertheless, a number of potential new agents for this indication are now under development. AREAS COVERED The following review describes the most recently developed agents in preclinical as well as Phase 1 and Phase 2 clinical studies. Information was obtained from published literature, abstracts and the latest results found in Clinicaltrial.gov database. The authors put a special interest on glucagon-like peptide 1 analogue, bile acid modulators, serotonergic agents, guanylate cyclase C and cannabinoid antagonists. EXPERT OPINION To enter the market, a newly-developed drug has to meet several criteria, such as good bioavailability or the absence of drug-related adverse events. Taking into account constipation and abdominal pain as the main symptoms in IBS-C, a novel successful drug is usually able to improve both at the same time. Four out of fifteen investigational drugs described in this paper belong to the serotonergic family and have a good prognosis to reach the market; still, more long-term clinical studies are warranted.
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Affiliation(s)
- Paula Mosińska
- a Department of Biochemistry, Faculty of Medicine , Medical University of Lodz , Lodz , Poland
| | - Maciej Salaga
- a Department of Biochemistry, Faculty of Medicine , Medical University of Lodz , Lodz , Poland
| | - Jakub Fichna
- a Department of Biochemistry, Faculty of Medicine , Medical University of Lodz , Lodz , Poland
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