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Tang P, van den Broek DHN, Jepson RE, Geddes RF, Chang Y, Lötter N, Moniot D, Biourge V, Elliott J. Dietary magnesium supplementation in cats with chronic kidney disease: A prospective double-blind randomized controlled trial. J Vet Intern Med 2024; 38:2180-2195. [PMID: 38952053 PMCID: PMC11256178 DOI: 10.1111/jvim.17134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2024] [Accepted: 05/31/2024] [Indexed: 07/03/2024] Open
Abstract
BACKGROUND Plasma total magnesium concentration (tMg) is a prognostic indicator in cats with chronic kidney disease (CKD), shorter survival time being associated with hypomagnesemia. Whether this risk factor is modifiable with dietary magnesium supplementation remains unexplored. OBJECTIVES Evaluate effects of a magnesium-enriched phosphate-restricted diet (PRD) on CKD-mineral bone disorder (CKD-MBD) variables. ANIMALS Sixty euthyroid client-owned cats with azotemic CKD, with 27 and 33 allocated to magnesium-enriched PRD or control PRD, respectively. METHODS Prospective double-blind, parallel-group randomized trial. Cats with CKD, stabilized on a PRD, without hypermagnesemia (tMg >2.43 mg/dL) or hypercalcemia (plasma ionized calcium concentration, (iCa) >6 mg/dL), were recruited. Both intention-to-treat and per-protocol (eating ≥50% of study diet) analyses were performed; effects of dietary magnesium supplementation on clinicopathological variables were evaluated using linear mixed effects models. RESULTS In the per-protocol analysis, tMg increased in cats consuming a magnesium-enriched PRD (β, 0.25 ± .07 mg/dL/month; P < .001). Five magnesium supplemented cats had tMg >2.92 mg/dL, but none experienced adverse effects. Rate of change in iCa differed between groups (P = .01), with decreasing and increasing trends observed in cats fed magnesium-enriched PRD and control PRD, respectively. Four control cats developed ionized hypercalcemia versus none in the magnesium supplemented group. Log-transformed plasma fibroblast growth factor-23 concentration (FGF23) increased significantly in controls (β, 0.14 ± .05 pg/mL/month; P = .01), but remained stable in the magnesium supplemented group (β, 0.05±.06 pg/mL/month; P =.37). CONCLUSIONS AND CLINICAL IMPORTANCE Magnesium-enriched PRD is a novel therapeutic strategy for managing feline CKD-MBD in cats, further stabilizing plasma FGF23 and preventing hypercalcemia.
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Affiliation(s)
- Pak‐Kan Tang
- Department of Comparative Biomedical Sciences, Royal Veterinary CollegeUniversity of LondonLondonUnited Kingdom
| | | | - Rosanne E. Jepson
- Department of Clinical Science and Services, Royal Veterinary CollegeUniversity of LondonLondonUnited Kingdom
| | - Rebecca F. Geddes
- Department of Clinical Science and Services, Royal Veterinary CollegeUniversity of LondonLondonUnited Kingdom
| | - Yu‐Mei Chang
- Research Support Office, Royal Veterinary CollegeUniversity of LondonLondonUnited Kingdom
- Present address:
Department of Comparative Biomedical SciencesRoyal Veterinary College, University of LondonLondonUnited Kingdom
| | - Nicola Lötter
- Department of Comparative Biomedical Sciences, Royal Veterinary CollegeUniversity of LondonLondonUnited Kingdom
| | | | | | - Jonathan Elliott
- Department of Comparative Biomedical Sciences, Royal Veterinary CollegeUniversity of LondonLondonUnited Kingdom
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2
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The importance of kidney calcium handling in the homeostasis of extracellular fluid calcium. Pflugers Arch 2022; 474:885-900. [PMID: 35842482 DOI: 10.1007/s00424-022-02725-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/09/2022] [Accepted: 06/30/2022] [Indexed: 12/13/2022]
Abstract
Extracellular fluid calcium concentration must be maintained within a narrow range in order to sustain many biological functions, encompassing muscle contraction, blood coagulation, and bone and tooth mineralization. Blood calcium value is critically dependent on the ability of the renal tubule to reabsorb the adequate amount of filtered calcium. Tubular calcium reabsorption is carried out by various and complex mechanisms in 3 distinct segments: the proximal tubule, the cortical thick ascending limb of the loop of Henle, and the late distal convoluted/connecting tubule. In addition, calcium reabsorption is tightly controlled by many endocrine, paracrine, and autocrine factors, as well as by non-hormonal factors, in order to adapt the tubular handling of calcium to the metabolic requirements. The present review summarizes the current knowledge of the mechanisms and factors involved in calcium handling by the kidney and, ultimately, in extracellular calcium homeostasis. The review also highlights some of our gaps in understanding that need to be addressed in the future.
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Matsuo T, Ito H, Mitsunari K, Ohba K, Miyata Y. Relationship between Urinary Calcium Excretion and Lower Urinary Tract Symptoms. Metabolites 2022; 12:metabo12030229. [PMID: 35323672 PMCID: PMC8953485 DOI: 10.3390/metabo12030229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/02/2022] [Accepted: 03/04/2022] [Indexed: 12/10/2022] Open
Abstract
To date, few detailed studies have been conducted on the convenient and useful markers for the prevalence of lower urinary tract symptoms (LUTS), including overactive bladder (OAB) and nocturia. A high level of calcium (Ca) excretion (hypercalciuria) is indicative of lifestyle-related diseases such as hypertension, which are associated with the onset of LUTS. Hence, in this study we attempted to clarify the relationship between urinary Ca excretion and OAB, nocturia, and nocturnal polyuria in adults. The present study showed that patients with hypercalciuria frequently experienced OAB, nocturia, and nocturnal polyuria. In addition, this study revealed that the severity of LUTS is significantly associated with urinary Ca excretion and that hypercalciuria is an important risk factor for OAB, nocturia, and nocturnal polyuria.
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Liu J, Tio MC, Verma A, Schmidt IM, Ilori TO, Knauf F, Mc Causland FR, Waikar SS. Determinants and Outcomes Associated With Urinary Calcium Excretion in Chronic Kidney Disease. J Clin Endocrinol Metab 2022; 107:e281-e292. [PMID: 34390334 PMCID: PMC8684460 DOI: 10.1210/clinem/dgab574] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Indexed: 02/08/2023]
Abstract
CONTEXT Abnormalities in calcium metabolism are common in chronic kidney disease (CKD). Diminished urinary calcium excretion may promote vascular calcification and increased urinary calcium excretion may lead to nephrolithiasis and nephrocalcinosis, conditions associated with CKD. OBJECTIVE To study predictors of urinary calcium excretion and its association with adverse clinical outcomes in CKD. DESIGN, SETTING AND PATIENTS This study assessed 3768 nondialysis participants in the Chronic Renal Insufficiency Cohort study from April 2003 to September 2008. Participants were followed up to October 2018. EXPOSURE Clinically plausible predictors of urinary calcium excretion and 24-h urinary calcium excretion at baseline. MAIN OUTCOME MEASURES Urinary calcium excretion; incident end stage kidney disease (ESKD), CKD progression [50% estimated glomerular filtration rate (eGFR) decline or incident ESKD], all-cause mortality, and atherosclerotic cardiovascular disease events. RESULTS eGFR was positive correlated with 24-h urinary calcium excretion. The variables most strongly associated with 24-h urinary calcium excretion in males and females were 24-h urinary sodium (β = 0.19 and 0.28, respectively), serum parathyroid hormone (β = -0.22 and -0.20, respectively), loop diuretics (β = 0.36 and 0.26, respectively), thiazide diuretics (β = -0.49 and -0.53, respectively), and self-identified black race (β = -0.23 and -0.27, respectively). Lower urinary calcium excretion was associated with greater risks of adverse outcomes, but these associations were greatly attenuated or nullified after adjustment for baseline eGFR. CONCLUSION Urinary calcium excretion is markedly lower in individuals with CKD compared to the general population. Determinants of urinary calcium excretion differed between sexes and levels of CKD. Associations between urinary calcium excretion and adverse clinical events were substantially confounded by eGFR.
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Affiliation(s)
- Jing Liu
- Renal Division, Kidney Research Institute, West China Hospital of Sichuan University, Chengdu, China
- Section of Nephrology, Department of Medicine, Boston University School of Medicine and Boston Medical Center, Boston, MA, USA
| | - Maria Clarissa Tio
- Renal Division, Brigham & Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Ashish Verma
- Renal Division, Brigham & Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Insa M Schmidt
- Section of Nephrology, Department of Medicine, Boston University School of Medicine and Boston Medical Center, Boston, MA, USA
- Renal Division, Brigham & Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Titilayo O Ilori
- Section of Nephrology, Department of Medicine, Boston University School of Medicine and Boston Medical Center, Boston, MA, USA
| | - Felix Knauf
- Department of Nephrology and Medical Intensive Care, Charité Universitätsmedizin Berlin, Berlin, Germany
| | | | - Sushrut S Waikar
- Section of Nephrology, Department of Medicine, Boston University School of Medicine and Boston Medical Center, Boston, MA, USA
- Correspondence: Sushrut S. Waikar, MD, MPH, Boston Medical Center, Renal Section, Evans Biomedical Research Center, 650 Albany Street, X504, Boston, MA 02118, USA.
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5
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Wu WY, Lee SP, Chiang BJ, Lin WY, Chien CT. Urothelial Calcium-Sensing Receptor Modulates Micturition Function via Mediating Detrusor Activity and Ameliorates Bladder Hyperactivity in Rats. Pharmaceuticals (Basel) 2021; 14:ph14100960. [PMID: 34681183 PMCID: PMC8537609 DOI: 10.3390/ph14100960] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/20/2021] [Accepted: 09/20/2021] [Indexed: 12/19/2022] Open
Abstract
The urothelium displays mechano- and chemosensory functions via numerous receptors and channels. The calcium-sensing receptor (CaSR) detects extracellular calcium and modulates several physiological functions. Nonetheless, information about the expression and the role of CaSR in lower urinary tract has been absent. We aimed to determine the existence of urothelial CaSR in urinary bladder and its effect on micturition function. We utilized Western blot to confirm the expression of CaSR in bladder and used immunofluorescence to verify the location of the CaSR in the bladder urothelium via colocalization with uroplakin III A. The activation of urothelial CaSR via the CaSR agonist, AC-265347 (AC), decreased urinary bladder smooth muscle (detrusor) activity, whereas its inhibition via the CaSR antagonist, NPS-2143 hydrochloride (NPS), increased detrusor activity in in vitro myography experiments. Cystometry, bladder nerve activities recording, and bladder surface microcirculation detection were conducted to evaluate the effects of the urothelial CaSR via intravesical administrations. Intravesical AC inhibited micturition reflex, bladder afferent and efferent nerve activities, and reversed cystitis-induced bladder hyperactivity. The urothelial CaSR demonstrated a chemosensory function, and modulated micturition reflex via regulating detrusor activity. This study provided further evidence of how the urothelial CaSR mediated micturition and implicated the urothelial CaSR as a potential pharmacotherapeutic target in the intervention of bladder disorders.
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Affiliation(s)
- Wei-Yi Wu
- Department of Life Science, School of Life Science, College of Science, National Taiwan Normal University, Taipei 11677, Taiwan;
| | - Shih-Pin Lee
- Department of Public Health, International College, Krirk University, Bangkok 10220, Thailand;
| | - Bing-Juin Chiang
- Department of Life Science, School of Life Science, College of Science, National Taiwan Normal University, Taipei 11677, Taiwan;
- College of Medicine, Fu-Jen Catholic University, New Taipei City 24205, Taiwan
- Department of Urology, Cardinal Tien Hospital, New Taipei City 23148, Taiwan
- Correspondence: (B.-J.C.); (W.-Y.L.); (C.-T.C.); Tel.: +886-2-77496312 (C.-T.C.)
| | - Wei-Yu Lin
- Department of Life Science, School of Life Science, College of Science, National Taiwan Normal University, Taipei 11677, Taiwan;
- Department of Urology, Ministry of Health and Welfare, Taipei Hospital, New Taipei City 24213, Taiwan
- Correspondence: (B.-J.C.); (W.-Y.L.); (C.-T.C.); Tel.: +886-2-77496312 (C.-T.C.)
| | - Chiang-Ting Chien
- Department of Life Science, School of Life Science, College of Science, National Taiwan Normal University, Taipei 11677, Taiwan;
- Correspondence: (B.-J.C.); (W.-Y.L.); (C.-T.C.); Tel.: +886-2-77496312 (C.-T.C.)
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Ferreira PG, van Megen WH, Tan R, Lee CHL, Svenningsen P, Alexander RT, Dimke H. Renal claudin-14 expression is not required for regulating Mg 2+ balance in mice. Am J Physiol Renal Physiol 2021; 320:F897-F907. [PMID: 33818126 DOI: 10.1152/ajprenal.00590.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The kidneys play a crucial role in maintaining Ca2+ and Mg2+ homeostasis by regulating these minerals' reabsorption. In the thick ascending limb of Henle's loop (TAL), Ca2+ and Mg2+ are reabsorbed through the tight junctions by a shared paracellular pathway formed by claudin-16 and claudin-19. Hypercalcemia activates the Ca2+-sensing receptor (CaSR) in the TAL, causing upregulation of pore-blocking claudin-14 (CLDN14), which reduces Ca2+ and Mg2+ reabsorption from this segment. In addition, a high-Mg2+ diet is known to increase both urinary Mg2+ and Ca2+ excretion. Since Mg2+ may also activate CaSR, we aimed to investigate whether CaSR-dependent increases in CLDN14 expression also regulate urinary Mg2+ excretion in response to hypermagnesemia. Here, we show that a Mg2+-enriched diet increased urinary Mg2+ and Ca2+ excretion in mice; however, this occurred without detectable changes in renal CLDN14 expression. The administration of a high-Mg2+ diet to Cldn14-/- mice did not cause more pronounced hypermagnesemia or significantly alter urinary Mg2+ excretion. Finally, in vitro evaluation of CaSR-driven Cldn14 promoter activity in response to increasing Mg2+ concentrations revealed that Cldn14 expression only increases at supraphysiological extracellular Mg2+ levels. Together, these results suggest that CLDN14 is not involved in regulating extracellular Mg2+ balance following high dietary Mg2+ intake.NEW & NOTEWORTHY Using transgenic models and in vitro assays, this study examined the effect of Mg2+ on regulating urinary excretion of Ca2+ and Mg2+ via activation of the Ca2+-sensing receptor-claudin 14 (CLDN14) pathway. The study suggests that CLDN14 is unlikely to play a significant role in the compensatory response to hypermagnesemia.
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Affiliation(s)
- Patrícia G Ferreira
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Wouter H van Megen
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Rebecca Tan
- Department of Physiology, The University of Alberta, Edmonton, Alberta, Canada
| | - Christy H L Lee
- Department of Physiology, The University of Alberta, Edmonton, Alberta, Canada
| | - Per Svenningsen
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - R Todd Alexander
- Department of Pediatrics, The University of Alberta, Edmonton, Alberta, Canada.,Membrane Protein Disease Research Group, The University of Alberta, Edmonton, Alberta, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark.,Department of Nephrology, Odense University Hospital, Odense, Denmark
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7
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Liu X, Chen R, Jiang L, Li X, Sun Z. Effect of infusion irrigation with different irrigating solutions on transient receptor potential vanilloid 5 and intra-articular inflammation in a post-traumatic osteoarthritis rabbit model. Eur J Med Res 2021; 26:24. [PMID: 33706812 PMCID: PMC7953622 DOI: 10.1186/s40001-021-00491-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 02/01/2021] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The incidence of post-traumatic osteoarthritis (PTOA) after anterior cruciate ligament reconstruction (ACLR) is high, but there is still a lack of intra-operative preventive measures. This study aimed to evaluate the effect of different irrigating solutions continuous irrigation on intra-articular inflammation and cartilage degeneration. METHODS 66 New Zealand rabbits were randomly divided into normal (N) group, no treatment (NT) group, sodium chloride (NaCl) group, magnesium sulfate (MgSO4) group, and calcium chloride (CaCl2) group. The right knee joint of the experimental group was utilized to construct the model of PTOA, and the left side was utilized as the normal control group. At different time points postoperatively, the blood concentration of hemoglobin and Mg2 + , the synovial fluid concentration of IL-1 β, TNF-α, tartrate-resistant acid phosphatase-5b (TRAP-5b), and Type II Collagen, the gene expression of IL-1 β and MMP-3, and the protein expression of TRPV5 and CaM were detected. Pearson's linear correlation was employed to identify the possible relationship between the expression of TRAP-5b and the expression of IL-1β, IL-6, TNF-α, and Type II collagen. The hematoxylin and eosin staining (HE), Masson's trichrome staining, and Alcian blue staining were performed at postoperative 35 days. Osteoarthritis Scoring (OA score) comprised categories including Alcian blue staining, cartilage histology, the cellular density of cartilage, degree of cell disintegration, and formation of chondrocyte cluster were blindly scored by trained researchers at postoperative 35 days. RESULTS There was no statistical difference (P > 0.05) in the hemoglobin concentration between different groups. The concentration of serum Mg2+ in the MgSO4 group was higher than that of the other three groups (P < 0.05) on the same day of operation, then gradually decreased. The expression of IL-1 β, IL-6, and TRAP-5b in synovial fluid increased 5 days after the operation, decreased at 15 days, and then increased again with time in the NT group, NaCl group, and NT group and NaCl group. At 35 days after the operation, the expression of IL-1 β, IL-6, TRAP-5b, and type II collagen in the MgSO4 group were lower than that in the other three groups (except group N) (P < 0.05).The correlation analysis results showed that the TRAP-5b levels correlated positively with IL-1 β, IL-6, TNF-α, and type II collagen concentrations. The histological examination revealed that the surface smoothness of cartilage, the morphology of chondrocytes, the arrangement of collagen fibers, and the density of proteoglycan in the MgSO4 group were better than those in other experimental groups. At 35 days postoperatively, the gene expression of IL-1 β and MMP-3 and the protein expression of CaM and TRPV5 in synovium in the MgSO4 group was lower than that in the NaCl group and CaCl2 group. CONCLUSION Intra-operative irrigation with magnesium sulfate solution can inhibit the inflammatory factors and the expression of TRPV5, which can also reduce collagen loss and delay cartilage degeneration. Therefore, the use of magnesium sulfate in intra-operative irrigation may be an ideal choice to prevent PTOA.
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Affiliation(s)
- Xinghui Liu
- Department of Anatomy, Hubei University of Medicine, Shiyan, 442000 Hubei China
| | - Rong Chen
- Department of Traumatic Orthopedics, RenminHospital, Hubei University of Medicine, No.39 Chaoyang Road, Maojian District, Shiyan, 442000 Hubei China
| | - Liangbo Jiang
- Department of Traumatic Orthopedics, RenminHospital, Hubei University of Medicine, No.39 Chaoyang Road, Maojian District, Shiyan, 442000 Hubei China
| | - Xiangwei Li
- Department of Traumatic Orthopedics, RenminHospital, Hubei University of Medicine, No.39 Chaoyang Road, Maojian District, Shiyan, 442000 Hubei China
| | - Zhibo Sun
- Department of Traumatic Orthopedics, RenminHospital, Hubei University of Medicine, No.39 Chaoyang Road, Maojian District, Shiyan, 442000 Hubei China
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8
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Shafiee MA, Shaker P, Hosseini SF, Alavinia M, Aarabi M, Rezaee AJ, Halperin ML. Are individual analyses of multiple short urine collections throughout the 24 hours superior to a standard 24-hour urine collection in precipitation risk assessment of healthy subjects? Nephrology (Carlton) 2020; 26:234-238. [PMID: 33314554 DOI: 10.1111/nep.13842] [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: 06/21/2020] [Revised: 11/23/2020] [Accepted: 12/07/2020] [Indexed: 12/01/2022]
Abstract
PURPOSE The commonly used 24-hour collection technique has been the mainstay of diagnosis for supersaturation but has some certain limitations. Hence, superiority of multiple short urine collections as a new alternative in precipitation risk assessment was assessed compared to the standard 24-hour urine collection among healthy subjects. MATERIALS AND METHODS Individual urine samples of 26 healthy subjects were acquired every 2 to 3 hours throughout the 24 hours. Urine samples were obtained and the time and volume of each sample were recorded. Urinary constituents involved in precipitation including, sodium-potassium, chloride, calcium, phosphate, citrate, magnesium, urea, creatinine and pH were measured. A simulated 24-hour collection was recalculated by the totalling of all shorter urine collections volume and urinary constituents excretions throughout the day. RESULTS Urine pH, urine creatinine and precipitation rate had a significantly lower values in 24-hours urine collection compared to one individual value of multiple urine collections by -0.769 (P < .0001), -7.305 (P < .0001), and - 12.838 (P < .0001), respectively. However, calcium (2.697, P < .0001), citrate (3.54, P < .0001), total phosphate (19.961, P < .0001) and total creatinine (9.579, P < .0001) had statistically significantly higher values in the 24-hours urine collection compared to individual value of multiple urine collections. CONCLUSION Based on the results, individual analysis of multiple shorter urine collections throughout the day improves the ability of identifying supersaturation points, precipitation risk zones and may potentially improve risk assessment compared to the 24-hour urine collection method.
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Affiliation(s)
- Mohammad A Shafiee
- Division of General Internal Medicine, Department of Medicine, Toronto General Hospital, Toronto, Ontario, Canada
| | - Pouyan Shaker
- Division of General Internal Medicine, Department of Medicine, Toronto General Hospital, Toronto, Ontario, Canada
| | - Sayyideh F Hosseini
- Division of General Internal Medicine, Department of Medicine, Toronto General Hospital, Toronto, Ontario, Canada
| | - Mohammad Alavinia
- Neural Engineering and Therapeutic Team, Lyndhurst Centre, KITE-Toronto Rehab, University Health Network, Toronto, Ontario, Canada
| | - Mehdi Aarabi
- Division of General Internal Medicine, Department of Medicine, Toronto General Hospital, Toronto, Ontario, Canada
| | - Ali J Rezaee
- Division of General Internal Medicine, Department of Medicine, Toronto General Hospital, Toronto, Ontario, Canada
| | - Mitchel L Halperin
- Division of General Internal Medicine, Department of Medicine, Toronto General Hospital and Li Ka Shing Knowledge Institute of St. Michael's Hospital and Division of Nephrology, University of Toronto (MLH), Toronto, Ontario, Canada
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9
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Imenez Silva PH, Katamesh-Benabbas C, Chan K, Pastor Arroyo EM, Knöpfel T, Bettoni C, Ludwig MG, Gasser JA, Brandao-Burch A, Arnett TR, Bonny O, Seuwen K, Wagner CA. The proton-activated ovarian cancer G protein-coupled receptor 1 (OGR1) is responsible for renal calcium loss during acidosis. Kidney Int 2020; 97:920-933. [DOI: 10.1016/j.kint.2019.12.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 11/29/2019] [Accepted: 12/05/2019] [Indexed: 12/19/2022]
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10
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Wiegand A, Fischer G, Seeger H, Fuster D, Dhayat N, Bonny O, Ernandez T, Kim MJ, Wagner CA, Mohebbi N. Impact of potassium citrate on urinary risk profile, glucose and lipid metabolism of kidney stone formers in Switzerland. Clin Kidney J 2019; 13:1037-1048. [PMID: 33391747 PMCID: PMC7769539 DOI: 10.1093/ckj/sfz098] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 07/08/2019] [Indexed: 01/25/2023] Open
Abstract
Background Hypocitraturia and hypercalciuria are the most prevalent risk factors in kidney stone formers (KSFs). Citrate supplementation has been introduced for metaphylaxis in KSFs. However, beyond its effects on urinary parameters and stone recurrence, only a few studies have investigated the impact of citrate on other metabolic pathways such as glucose or lipid metabolism. Methods We performed an observational study using data from the Swiss Kidney Stone Cohort. Patients were subdivided into two groups based on treatment with potassium citrate or not. The outcomes were changes of urinary risk parameters, haemoglobin A1c (HbA1c), fasting glucose, cholesterol and body mass index (BMI). Results Hypocitraturia was present in 19.3% of 428 KSFs and potassium citrate was administered to 43 patients (10.0%) at a mean dosage of 3819 ± 1796 mg/day (corresponding to 12.5 ± 5.9 mmol/ day). Treatment with potassium citrate was associated with a significantly higher mean change in urinary citrate (P = 0.010) and urinary magnesium (P = 0.020) compared with no potassium citrate treatment. Exogenous citrate administration had no effect on cholesterol, fasting glucose, HbA1c and BMI. Multiple linear regression analysis demonstrated no significant association of 1,25-dihydroxyvitamin D3 [1,25(OH)2 D3] levels with urinary citrate excretion. Conclusion Potassium citrate supplementation in KSFs in Switzerland resulted in a beneficial change of the urinary risk profile by particularly increasing anti-lithogenic factors. Fasting glucose, HbA1c, cholesterol levels and BMI were unaffected by potassium citrate therapy after 3 months, suggesting that potassium citrate is safe and not associated with unfavourable metabolic side effects. Lastly, 1,25(OH)2 D3 levels were not associated with urinary citrate excretion.
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Affiliation(s)
- Anna Wiegand
- Division of Nephrology, University Hospital of Zurich, Zurich, Switzerland
| | - Gioia Fischer
- Division of Nephrology, University Hospital of Zurich, Zurich, Switzerland
| | - Harald Seeger
- Division of Nephrology, University Hospital of Zurich, Zurich, Switzerland.,Swiss Kidney Stone Cohort, National Center of Competence in Research, NCCR-Kidney, Switzerland
| | - Daniel Fuster
- Swiss Kidney Stone Cohort, National Center of Competence in Research, NCCR-Kidney, Switzerland.,Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Nasser Dhayat
- Swiss Kidney Stone Cohort, National Center of Competence in Research, NCCR-Kidney, Switzerland.,Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Olivier Bonny
- Swiss Kidney Stone Cohort, National Center of Competence in Research, NCCR-Kidney, Switzerland.,Service of Nephrology, University Hospital of Lausanne, Lausanne, Switzerland
| | - Thomas Ernandez
- Swiss Kidney Stone Cohort, National Center of Competence in Research, NCCR-Kidney, Switzerland.,Service of Nephrology, University Hospital of Geneva, Geneva, Switzerland
| | - Min-Jeong Kim
- Swiss Kidney Stone Cohort, National Center of Competence in Research, NCCR-Kidney, Switzerland.,Clinic for Transplantation Immunology and Nephrology, University Hospital Basel, Basel, Switzerland
| | - Carsten A Wagner
- Swiss Kidney Stone Cohort, National Center of Competence in Research, NCCR-Kidney, Switzerland.,Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Nilufar Mohebbi
- Division of Nephrology, University Hospital of Zurich, Zurich, Switzerland.,Swiss Kidney Stone Cohort, National Center of Competence in Research, NCCR-Kidney, Switzerland
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Meurer M, Höcherl K. Endotoxaemia differentially regulates the expression of renal Ca 2+ transport proteins in mice. Acta Physiol (Oxf) 2019; 225:e13175. [PMID: 30133162 DOI: 10.1111/apha.13175] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 08/17/2018] [Accepted: 08/18/2018] [Indexed: 12/16/2022]
Abstract
AIM Alterations in parathyroid hormone (PTH) and/or vitamin D signalling are frequently reported in patients with sepsis. The consequences on renal and intestinal Ca2+ and Pi regulatory mechanisms are still unclear. We hypothesized that endotoxaemia alters the expression of important renal and intestinal Ca2+ and Pi transport proteins. METHODS Male C57BL/6 mice were treated with lipopolysaccharide (LPS; 3 mg/kg; i.p.). The mRNA and protein levels of renal and intestinal Ca2+ and Pi transport proteins were measured by RT-qPCR, immunohistochemistry and western blot analysis. RESULTS Lipopolysaccharide-induced hypocalcaemia and hyperphosphataemia was paralleled by a decrease in glomerular filtration rate and urinary excretion of Ca2+ and Pi . Endotoxaemia augmented plasma levels of PTH and affected the fibroblast growth factor 23 (FGF23)-klotho-vitamin D axis by increasing plasma levels of FGF23 and downregulation of renal klotho expression. Renal expression of CYP27b1 and plasma levels of 1,25-dihydroxyvitamin D3 were increased in response to LPS. Endotoxaemia augmented the renal expression of TRPV5, TRPV6 and PiT1, whereas the renal expression of calbindin-D28K , NCX1, NaPi -2a and NaPi -2c were decreased. Incubation of primary distal tubule cells with LPS increased TRPV6 mRNA levels. Furthermore, LPS decreased the intestinal expression of TRPV6, calbindin-D9K and of NaPi -2b. CONCLUSION Our findings indicate that endotoxaemia is associated with hypocalcaemia and hyperphosphataemia and a disturbed FGF23-klotho-vitamin D signaling. Further, LPS-induced acute kidney injury was accompanied by an increased or decreased expression of specific renal and intestinal Ca2+ and Pi transporters respectively. It seems unlikely that LPS-induced hypocalcaemia is due to renal loss of Ca2+ .
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Affiliation(s)
- Manuel Meurer
- Institute of Experimental and Clinical Pharmacology and Toxicology; Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU); Erlangen Germany
| | - Klaus Höcherl
- Institute of Experimental and Clinical Pharmacology and Toxicology; Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU); Erlangen Germany
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12
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Karhu E, Atlas SE, Gao J, Mehdi SA, Musselman D, Goldberg S, Woolger JM, Corredor R, Abbas MH, Arosemena L, Caccamo S, Farooqi A, Konefal J, Lantigua L, Padilla V, Rasul A, Tiozzo E, Higuera OL, Fiallo A, Lewis JE. Intravenous infusion of magnesium sulfate is not associated with cardiovascular, liver, kidney, and metabolic toxicity in adults. J Clin Transl Res 2018; 4:47-55. [PMID: 30873494 PMCID: PMC6410632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND Magnesium (Mg) deficiency contributes to the pathophysiology of numerous diseases. The therapeutic use of Mg has steadily increased over time. The increased in-hospital use of intravenous (IV) magnesium sulfate (MgSO4) warrants more extensive investigation regarding the safety of the therapy. The aim of this study was to determine the safety of IV MgSO4 infusion on cardiovascular, liver, kidney, and metabolic markers in adults. METHODS Twelve volunteers were randomized to one of two cross-over conditions: (a) IV infusion of MgSO4 in 5% dextrose followed by IV infusion of 5% dextrose 1 week later or (b) IV infusion of 5% dextrose followed by IV infusion of MgSO4 in 5% dextrose 1 week later. An electrocardiogram was recorded continuously during the infusions. Blood was drawn pre- and post-infusion for blood count (high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides). Results: Serum Mg increased from pre- to post-infusion in the MgSO4 + 5% dextrose group (p < 0.0001). The QRS interval length increased from pre- to post-infusion in the MgSO4 + 5% dextrose group (p < 0.04). Additionally, serum glucose concentration increased in the MgSO4 + 5% dextrose group (p = 0.04). These significant findings were modeled with gender and age as covariates. No other significant differences were found. CONCLUSIONS The administration of IV infusion of MgSO4 (4 g/100 mL) in 5% dextrose over a 4-hour treatment period poses no significant deleterious effects on cardiovascular, liver, kidney, or metabolic function. RELEVANCE FOR PATIENTS IV infusion of MgSO4 may be used for certain treatment indications without significant concern for systemic or organ toxicity.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | - Janet Konefal
- 5 Family Medicine and Community Health, University of Miami Miller School of Medicine, Miami, FL, USA
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13
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Abstract
Magnesium (Mg2+) is an essential mineral without known specific regulatory mechanisms. In ruminants, plasma Mg2+ concentration depends primarily on the balance between Mg2+ absorption and Mg2+ excretion. The primary site of Mg2+ absorption is the rumen, where Mg2+ is apically absorbed by both potential-dependent and potential-independent uptake mechanisms, reflecting involvement of ion channels and electroneutral transporters, respectively. Transport is energised in a secondary active manner by a basolateral Na+/Mg2+ exchanger. Ruminal transport of Mg2+ is significantly influenced by a variety of factors such as high K+ concentration, sudden increases of ammonia, pH, and the concentration of SCFA. Impaired Mg2+ absorption in the rumen is not compensated for by increased transport in the small or large intestine. While renal excretion can be adjusted to compensate precisely for any surplus in Mg2+ uptake, a shortage in dietary Mg2+ cannot be compensated for either via skeletal mobilisation of Mg2+ or via up-regulation of ruminal absorption. In such situations, hypomagnesaemia will lead to decrease of a Mg2+ in the cerebrospinal fluid and clinical manifestations of tetany. Improved knowledge concerning the factors governing Mg2+ homeostasis will allow reliable recommendations for an adequate Mg2+ intake and for the avoidance of possible disturbances. Future research should clarify the molecular identity of the suggested Mg2+ transport proteins and the regulatory mechanisms controlling renal Mg excretion as parameters influencing Mg2+ homeostasis.
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14
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Diaz-Tocados JM, Peralta-Ramirez A, Rodríguez-Ortiz ME, Raya AI, Lopez I, Pineda C, Herencia C, Montes de Oca A, Vergara N, Steppan S, Pendon-Ruiz de Mier MV, Buendía P, Carmona A, Carracedo J, Alcalá-Díaz JF, Frazao J, Martínez-Moreno JM, Canalejo A, Felsenfeld A, Rodriguez M, Aguilera-Tejero E, Almadén Y, Muñoz-Castañeda JR. Dietary magnesium supplementation prevents and reverses vascular and soft tissue calcifications in uremic rats. Kidney Int 2017; 92:1084-1099. [DOI: 10.1016/j.kint.2017.04.011] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 03/21/2017] [Accepted: 04/06/2017] [Indexed: 01/14/2023]
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15
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Ferré N, Rubio-Torrents C, Luque V, Closa-Monasterolo R, Grote V, Koletzko B, Socha P, Gruszfeld D, Langhendries JP, Sengier A, Verduci E, Escribano J. Influence of Feeding Types during the First Months of Life on Calciuria Levels in Healthy Infants: A Secondary Analysis from a Randomized Clinical Trial. ANNALS OF NUTRITION AND METABOLISM 2017; 70:132-139. [DOI: 10.1159/000468156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 02/18/2017] [Indexed: 11/19/2022]
Abstract
Background/Aims: Dietary factors can modify calciuria. We aim to investigate urinary calcium excretion in healthy infants according to their protein. Methods: Secondary data analysis from a randomized clinical trial where healthy term infants were randomized after birth to a higher (HP) or lower (LP) protein content formula that was consumed until age 1 year. A non-randomized group of breastfed (BF) infants was used for reference. Anthropometry, dietary intakes and calciuria (calcium/creatinine ratios) from spot urine samples were assessed at ages 3 and 6 months. At 6 months, the kidney volumes were assessed using ultrasonography, and the serum urea and creatinine levels were determined. Results: BF infants showed the highest calciuria levels, followed by the HP and the LP groups (p < 0.001 for all comparisons). Either protein intakes or formula types modulated the calciuria in linear regression models adjusted for other influencing dietary factors. The usual cut-off values classified 37.8% (BF), 16.8% (HP) and 4.9% (LP) of the infants as hypercalciuric. Conclusions: Feeding types during the first months of life affect calciuria, with BF infants presenting the highest levels. We propose new cut-off values, based on feeding types, to prevent the overestimation in hypercalciuria diagnoses among BF infants.
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16
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Affiliation(s)
- Seon-Ho Ahn
- Division of Nephrology, Department of Internal Medicine, Wonkwang University School of Medicine and Hospital, Iksan, Korea
| | - Jong Hwan Jung
- Division of Nephrology, Department of Internal Medicine, Wonkwang University School of Medicine and Hospital, Iksan, Korea
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17
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Mumtaz R, Trepiccione F, Hennings JC, Huebner AK, Serbin B, Picard N, Ullah AKMS, Păunescu TG, Capen DE, Lashhab RM, Mouro-Chanteloup I, Alper SL, Wagner CA, Cordat E, Brown D, Eladari D, Hübner CA. Intercalated Cell Depletion and Vacuolar H +-ATPase Mistargeting in an Ae1 R607H Knockin Model. J Am Soc Nephrol 2016; 28:1507-1520. [PMID: 27932475 DOI: 10.1681/asn.2016020169] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 11/08/2016] [Indexed: 12/27/2022] Open
Abstract
Distal nephron acid secretion is mediated by highly specialized type A intercalated cells (A-ICs), which contain vacuolar H+-ATPase (V-type ATPase)-rich vesicles that fuse with the apical plasma membrane on demand. Intracellular bicarbonate generated by luminal H+ secretion is removed by the basolateral anion-exchanger AE1. Chronically reduced renal acid excretion in distal renal tubular acidosis (dRTA) may lead to nephrocalcinosis and renal failure. Studies in MDCK monolayers led to the proposal of a dominant-negative trafficking mechanism to explain AE1-associated dominant dRTA. To test this hypothesis in vivo, we generated an Ae1 R607H knockin mouse, which corresponds to the most common dominant dRTA mutation in human AE1, R589H. Compared with wild-type mice, heterozygous and homozygous R607H knockin mice displayed incomplete dRTA characterized by compensatory upregulation of the Na+/HCO3- cotransporter NBCn1. Red blood cell Ae1-mediated anion-exchange activity and surface polypeptide expression did not change. Mutant mice expressed far less Ae1 in A-ICs, but basolateral targeting of the mutant protein was preserved. Notably, mutant mice also exhibited reduced expression of V-type ATPase and compromised targeting of this proton pump to the plasma membrane upon acid challenge. Accumulation of p62- and ubiquitin-positive material in A-ICs of knockin mice suggested a defect in the degradative pathway, which may explain the observed loss of A-ICs. R607H knockin did not affect type B intercalated cells. We propose that reduced basolateral anion-exchange activity in A-ICs inhibits trafficking and regulation of V-type ATPase, compromising luminal H+ secretion and possibly lysosomal acidification.
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Affiliation(s)
- Rizwan Mumtaz
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany
| | - Francesco Trepiccione
- Institut National de la Santé et de la Recherche Médicale U970, Paris Cardiovascular Research Center, Paris Descartes University, Department of Physiology, Hôpital Européen Georges Pompidou, Paris, France.,Department of Cardio-Thoracic and Respiratory Science, Second University of Naples, Naples, Italy
| | - J Christopher Hennings
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany
| | - Antje K Huebner
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany
| | - Bettina Serbin
- Institut National de la Santé et de la Recherche Médicale U970, Paris Cardiovascular Research Center, Paris Descartes University, Department of Physiology, Hôpital Européen Georges Pompidou, Paris, France
| | - Nicolas Picard
- Centre National de la Recherche Scientifique, Équipe de Recherche Labellisée 8228, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche en Santé 1138, Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, Paris, France
| | - A K M Shahid Ullah
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Teodor G Păunescu
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and
| | - Diane E Capen
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and
| | - Rawad M Lashhab
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Isabelle Mouro-Chanteloup
- Institut National de la Transfusion Sanguine, Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche en Santé 1134, Laboratory of Excellence Globule Rouge-Excellence, Paris Diderot University, Paris, France
| | - Seth L Alper
- Nephrology Division and Vascular Biology Research Center, Beth Israel Deaconess Medical Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland; and
| | - Emmanuelle Cordat
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Dennis Brown
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and
| | - Dominique Eladari
- Service de Physiologie Explorations Fonctionnelles Rénales, Centre Hospitalier Universitaire de la Réunion, Hôpital Felix Guyon; and .,Institut National de la Santé et de la Recherche Médicale U1188 Diabète athérothrombose Thérapies Réunion Océan Indien (DéTROI), Saint Denis, La Réunion, France
| | - Christian A Hübner
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany;
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18
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Corre T, Olinger E, Harris SE, Traglia M, Ulivi S, Lenarduzzi S, Belge H, Youhanna S, Tokonami N, Bonny O, Houillier P, Polasek O, Deary IJ, Starr JM, Toniolo D, Gasparini P, Vollenweider P, Hayward C, Bochud M, Devuyst O. Common variants in CLDN14 are associated with differential excretion of magnesium over calcium in urine. Pflugers Arch 2016; 469:91-103. [DOI: 10.1007/s00424-016-1913-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 11/22/2016] [Indexed: 12/17/2022]
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19
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Parajuli S, Clark DF, Djamali A. Is Kidney Transplantation a Better State of CKD? Impact on Diagnosis and Management. Adv Chronic Kidney Dis 2016; 23:287-294. [PMID: 27742382 DOI: 10.1053/j.ackd.2016.09.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Patients with CKD are at increased risk for cardiovascular events, hospitalizations, and mortality. Kidney transplantation (KTx) is the preferred treatment for end-stage kidney disease. Although comorbidities including anemia and bone and mineral disease improve or are even halted after KTx, kidney transplant recipients carry higher cardiovascular mortality risk than the general population, as well as an increased risk of infections, malignancies, fractures, and obesity. When comparing CKD with CKD after transplantation (CKD-T), the rate of decline of estimated glomerular filtration rate (eGFR) is significantly lower in CKD-T. Higher rate of decline of eGFR has been associated with increased risk of mortality. However, due to the significant increased risk of mortality due to cardiovascular events, infections, and malignancies, many kidney transplant recipients may not benefit of decline in the rate of eGFR. Patients with CKD-T are a unique subset of patients with multiple traditional and transplant-specific risk factors. Proper management and appropriate preventive health measures may improve long-term patient and allograft survival in patients with CKD-T.
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20
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Lameris AL, Nevalainen PI, Reijnen D, Simons E, Eygensteyn J, Monnens L, Bindels RJM, Hoenderop JGJ. Segmental transport of Ca²⁺ and Mg²⁺ along the gastrointestinal tract. Am J Physiol Gastrointest Liver Physiol 2015; 308:G206-16. [PMID: 25477372 DOI: 10.1152/ajpgi.00093.2014] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Calcium (Ca(2+)) and magnesium (Mg(2+)) ions are involved in many vital physiological functions. Since dietary intake is the only source of minerals for the body, intestinal absorption is essential for normal homeostatic levels. The aim of this study was to characterize the absorption of Ca(2+) as well as Mg(2+) along the gastrointestinal tract at a molecular and functional level. In both humans and mice the Ca(2+) channel transient receptor potential vanilloid subtype 6 (TRPV6) is expressed in the proximal intestinal segments, whereas Mg(2+) channel transient receptor potential melastatin subtype 6 (TRPM6) is expressed in the distal parts of the intestine. A method was established to measure the rate of Mg(2+) absorption from the intestine in a time-dependent manner by use of (25)Mg(2+). In addition, local absorption of Ca(2+) and Mg(2+) in different segments of the intestine of mice was determined by using surgically implanted intestinal cannulas. By these methods, it was demonstrated that intestinal absorption of Mg(2+) is regulated by dietary needs in a vitamin D-independent manner. Also, it was shown that at low luminal concentrations, favoring transcellular absorption, Ca(2+) transport mainly takes place in the proximal segments of the intestine, whereas Mg(2+) absorption predominantly occurs in the distal part of the gastrointestinal tract. Vitamin D treatment of mice increased serum Mg(2+) levels and 24-h urinary Mg(2+) excretion, but not intestinal absorption of (25)Mg(2+). Segmental cannulation of the intestine and time-dependent absorption studies using (25)Mg(2+) provide new ways to study intestinal Mg(2+) absorption.
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Affiliation(s)
- Anke L Lameris
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Pasi I Nevalainen
- School of Medicine, University of Tampere, Tampere, Finland; Department of Internal Medicine, Tampere University Hospital, Tampere, Finland
| | - Daphne Reijnen
- Central Animal Facility, Radboud University, Nijmegen, The Netherlands; and
| | - Ellen Simons
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jelle Eygensteyn
- Department of General Instrumentation, Faculty of Sciences, Radboud University, Nijmegen, The Netherlands
| | - Leo Monnens
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - René J M Bindels
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G J Hoenderop
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands;
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21
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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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Paßlack N, Burmeier H, Brenten T, Neumann K, Zentek J. Short term effects of increasing dietary salt concentrations on urine composition in healthy cats. Vet J 2014; 201:401-5. [PMID: 24881513 DOI: 10.1016/j.tvjl.2014.04.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 03/20/2014] [Accepted: 04/21/2014] [Indexed: 10/25/2022]
Abstract
High dietary salt (NaCl) concentrations are assumed to be beneficial in preventing the formation of calcium oxalate (CaOx) uroliths in cats, since increased water intake and urine volume have been observed subsequent to intake. In human beings, dietary NaCl restriction is recommended for the prevention of CaOx urolith formation, since high NaCl intake is associated with increased urinary Ca excretion. The aim of the present study was to clarify the role of dietary NaCl in the formation of CaOx uroliths in cats. Eight cats received four diets that differed in Na and Cl concentrations (0.38-1.43% Na and 0.56-2.52% Cl dry matter, DM). Each feeding period consisted of a 21 day adaptation period, followed by a 7 day sampling period for urine collection. Higher dietary NaCl concentrations were associated with increased urine volume and renal Na excretion. Urinary Ca concentration was constant, but renal Ca excretion increased from 0.62 to 1.05 mg/kg bodyweight (BW)/day with higher dietary NaCl concentrations (P ≤ 0.05). Urinary oxalate (Ox), citrate, P and K concentrations decreased when NaCl intake was high (P ≤ 0.05), and urinary pH was low in all groups (6.33-6.45; P > 0.05). Relative supersaturation of CaOx in the urine was unaffected by dietary NaCl concentrations. In conclusion, the present study demonstrated several beneficial effects of high dietary NaCl intake over a relatively short time period. In particular, urinary Ca concentration remained unchanged because of increased urine volume. Decreased urinary Ox concentrations might help to prevent the formation of CaOx uroliths, but this should be verified in future studies in diseased or predisposed cats.
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Affiliation(s)
- N Paßlack
- Institute of Animal Nutrition, Department of Veterinary Medicine, Freie Universität Berlin, Königin-Luise-Str. 49, 14195 Berlin, Germany.
| | - H Burmeier
- Institute of Animal Nutrition, Department of Veterinary Medicine, Freie Universität Berlin, Königin-Luise-Str. 49, 14195 Berlin, Germany
| | - T Brenten
- Mars GmbH, Eitzer Straße 215, 27283 Verden, Germany
| | - K Neumann
- Institute of Biometry and Clinical Epidemiology, Charité, Universitätsmedizin Berlin, Hindenburgdamm 30, 12203 Berlin, Germany
| | - J Zentek
- Institute of Animal Nutrition, Department of Veterinary Medicine, Freie Universität Berlin, Königin-Luise-Str. 49, 14195 Berlin, Germany
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[Electrolyte disorders in preeclampsia. A case report]. Nephrol Ther 2014; 10:51-7. [PMID: 24411827 DOI: 10.1016/j.nephro.2013.10.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 10/08/2013] [Accepted: 10/13/2013] [Indexed: 11/27/2022]
Abstract
The occurrence of electrolyte disorders as hypocalcemia and/or hyponatremia is an uncommon event in preeclampsia, which can be the sign of serious situation, with potentially unfavourable consequences for the mother and her fœtus. Hyponatremia in the setting of preeclampsia is an indicator of severity, and requires the understanding of the etiologic mechanisms to initiate an appropriate treatment. Indeed the often-considered fluid restriction is rarely a treatment option for pregnant women. Hypocalcemia is a complication that must be monitored when a treatment with high doses of intravenous magnesium sulphate is introduced. In this context, hypocalcemia must be sought, with the exclusion of other etiologies as vitamin D deficiency, hypoparathyroidism or renal and extrarenal loss of calcium. A replacement therapy, intravenous or oral according to circumstances, should be considered in case of severe or symptomatic hypocalcemia.
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Abstract
TRPV5 is one of the two channels in the TRPV family that exhibit high selectivity to Ca(2+) ions. TRPV5 mediates Ca(2+) influx into cells as the first step to transport Ca(2+) across epithelia. The specialized distribution in the distal tubule of the kidney positions TRPV5 as a key player in Ca(2+) reabsorption. The responsiveness in expression and/or activity of TRPV5 to hormones such as 1,25-dihydroxyvitamin D3, parathyroid hormone, estrogen, and testosterone makes TRPV5 suitable for its role in the fine-tuning of Ca(2+) reabsorption. This role is further optimized by the modulation of TRPV5 trafficking and activity via its binding partners; co-expressed proteins; tubular factors such as calbindin-D28k, calmodulin, klotho, uromodulin, and plasmin; extracellular and intracellular factors such as proton, Mg(2+), Ca(2+), and phosphatidylinositol-4,5-bisphosphate; and fluid flow. These regulations allow TRPV5 to adjust its overall activity in response to the body's demand for Ca(2+) and to prevent kidney stone formation. A point mutation in mouse Trpv5 gene leads to hypercalciuria similar to Trpv5 knockout mice, suggesting a possible role of TRPV5 in hypercalciuric disorders in humans. In addition, the single nucleotide polymorphisms in Trpv5 gene prevalently present in African descents may contribute to the efficient renal Ca(2+) reabsorption among African descendants. TRPV5 represents a potential therapeutic target for disorders with altered Ca(2+) homeostasis.
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Affiliation(s)
- Tao Na
- Cell Collection and Research Center, Institute for Biological Product Control, National Institutes for Food and Drug Control, Beijing, China
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Soleimani M. SLC26 Cl-/HCO3- exchangers in the kidney: roles in health and disease. Kidney Int 2013; 84:657-66. [PMID: 23636174 PMCID: PMC10947778 DOI: 10.1038/ki.2013.138] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 01/25/2013] [Accepted: 02/14/2013] [Indexed: 12/30/2022]
Abstract
Solute-linked carrier 26 (SLC26) isoforms constitute a conserved family of anion transporters with 10 distinct members. Except for SLC26A5 (prestin), all can operate as multifunctional anion exchangers, with three members (SLC26A7, SLC26A9, and SLC26A11) also capable of functioning as chloride channels. Several SLC26 isoforms can specifically mediate Cl(-)/HCO(3)(-) exchange. These include SLC26A3, A4, A6, A7, A9, and A11, which are expressed in the kidney except for SLC26A3 (DRA), which is predominantly expressed in the intestine. SLC26 Cl(-)/HCO(3)(-) exchanger isoforms display unique nephron segment distribution patterns with distinct subcellular localization in the kidney tubules. Together with studies in pathophysiologic states and the examination of genetically engineered mouse models, the evolving picture points to important roles for the SLC26 family in health and disease states. This review summarizes recent advances in the characterization of the SLC26 Cl(-)/HCO(3)(-) exchangers in the kidney with emphasis on their essential role in diverse physiological processes, including chloride homeostasis, oxalate excretion and kidney stone formation, vascular volume and blood pressure regulation, and acid-base balance.
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Affiliation(s)
- Manoocher Soleimani
- 1] Center on Genetics of Transport and Epithelial Biology, University of Cincinnati, Cincinnati, Ohio, USA [2] Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio, USA [3] Department of Medicine, University of Cincinnati, Cincinnati, Ohio, USA
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Bonny O, Edwards A. Calcium reabsorption in the distal tubule: regulation by sodium, pH, and flow. Am J Physiol Renal Physiol 2012; 304:F585-600. [PMID: 23152295 DOI: 10.1152/ajprenal.00493.2012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We developed a mathematical model of Ca(2+) transport along the late distal convoluted tubule (DCT2) and the connecting tubule (CNT) to investigate the mechanisms that regulate Ca(2+) reabsorption in the DCT2-CNT. The model accounts for apical Ca(2+) influx across transient receptor potential vanilloid 5 (TRPV5) channels and basolateral Ca(2+) efflux via plasma membrane Ca(2+)-ATPase pumps and type 1 Na(+)/Ca(2+) exchangers (NCX1). Model simulations reproduce experimentally observed variations in Ca(2+) uptake as a function of extracellular pH, Na(+), and Mg(2+) concentration. Our results indicate that amiloride enhances Ca(2+) reabsorption in the DCT2-CNT predominantly by increasing the driving force across NCX1, thereby stimulating Ca(2+) efflux. They also suggest that because aldosterone upregulates both apical and basolateral Na(+) transport pathways, it has a lesser impact on Ca(2+) reabsorption than amiloride. Conversely, the model predicts that full NCX1 inhibition and parathyroidectomy each augment the Ca(2+) load delivered to the collecting duct severalfold. In addition, our results suggest that regulation of TRPV5 activity by luminal pH has a small impact, per se, on transepithelial Ca(2+) fluxes; the reduction in Ca(2+) reabsorption induced by metabolic acidosis likely stems from decreases in TRPV5 expression. In contrast, elevations in luminal Ca(2+) are predicted to significantly decrease TRPV5 activity via the Ca(2+)-sensing receptor. Nevertheless, following the administration of furosemide, the calcium-sensing receptor-mediated increase in Ca(2+) reabsorption in the DCT2-CNT is calculated to be insufficient to prevent hypercalciuria. Altogether, our model predicts complex interactions between calcium and sodium reabsorption in the DCT2-CNT.
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Affiliation(s)
- Olivier Bonny
- Department of Toxicology and Pharmacology, University of Lausanne, France
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Malcolm H, April H. The magnesium inhibition and arrested phagosome hypotheses: new perspectives on the evolution and ecology ofSymbiodiniumsymbioses. Biol Rev Camb Philos Soc 2012; 87:804-21. [DOI: 10.1111/j.1469-185x.2012.00223.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Barone S, Amlal H, Xu J, Soleimani M. Deletion of the Cl-/HCO3- exchanger pendrin downregulates calcium-absorbing proteins in the kidney and causes calcium wasting. Nephrol Dial Transplant 2011; 27:1368-79. [PMID: 21873623 DOI: 10.1093/ndt/gfr505] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The epithelial calcium channel (ECaC) (TRPV5) and the Cl-/HCO3- exchanger pendrin (SLC26A4) are expressed on the apical membrane of tubular cells in the distal nephron and play essential roles in calcium re-absorption and bicarbonate secretion, respectively, in the kidney. METHODS A combination of functional and molecular biology techniques were employed to examine the role of pendrin deletion in calcium excretion. RESULTS Here, we demonstrate that deletion of pendrin causes acidic urine [urine pH 4.9 in knockout (KO) versus 5.9 in wild-type (WT) mice, P<0.03)] and downregulates the calcium-absorbing molecules ECaC and Na/Ca exchanger in the kidney, as shown by northern hybridization, immunoblot analysis and/or immunofluorescent labeling. These changes were associated with a ∼100% increase in 24-h urine calcium excretion in pendrin null mice. Subjecting the pendrin WT and KO mice to oral bicarbonate loading for 12 days increased the urine pH to ∼8 in both genotypes, normalized the expression of ECaC and Na/Ca exchanger and reduced the urine calcium excretion in pendrin-null mice to levels comparable to WT mice. CONCLUSIONS We suggest that pendrin dysfunction should be suspected and investigated in humans with an otherwise unexplained acidic urine and hypercalciuria.
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Affiliation(s)
- Sharon Barone
- Research Services, Veterans Administration Medical Center, Cincinnati, OH, USA
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Abstract
The classic definition of hypercalciuria, an upper normal limit of 200 mg/day, is based on a constant diet restricted in calcium, sodium, and animal protein; however, random diet data challenge this. Here our retrospective study determined the validity of the classic definition of hypercalciuria by comparing data from 39 publications analyzing urinary calcium excretion on a constant restricted diet and testing whether hypercalciuria could be defined when extraneous dietary influences were controlled. These papers encompassed 300 non-stone-forming patients, 208 patients with absorptive hypercalciuria type I (presumed due to high intestinal calcium absorption), and 234 stone formers without absorptive hypercalciuria; all evaluated on a constant restricted diet. In non-stone formers, the mean urinary calcium was well below 200 mg/day, and the mean for all patients was 127±46 mg/day with an upper limit of 219 mg/day. In absorptive hypercalciuria type I, the mean urinary calcium significantly exceeded 200 mg/day in all studies with a combined mean of 259±55 mg/day. Receiver operating characteristic curve analysis showed the optimal cutoff point for urinary calcium excretion was 172 mg/day on a restricted diet, a value that approximates the traditional limit of 200 mg/day. Thus, on a restricted diet, a clear demarcation was seen between urinary calcium excretion of kidney stone formers with absorptive hypercalciuria type I and normal individuals. When dietary variables are controlled, the classic definition of hypercalciuria of nephrolithiasis appears valid.
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Influence of nutrition on feline calcium oxalate urolithiasis with emphasis on endogenous oxalate synthesis. Nutr Res Rev 2011; 24:96-110. [PMID: 21338551 DOI: 10.1017/s0954422410000351] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The prevalence of calcium oxalate (CaOx) uroliths detected in cats with lower urinary tract disease has shown a sharp increase over the last decades with a concomitant reciprocal decrease in the occurrence of struvite (magnesium ammonium phosphate) uroliths. CaOx stone-preventative diets are available nowadays, but seem to be marginally effective, as CaOx urolith recurrence occurs in patients fed these diets. In order to improve the preventative measures against CaOx urolithiasis, it is important to understand its aetiopathogenesis. The main research focus in CaOx formation in cats has been on the role of Ca, whereas little research effort has been directed towards the role and origin of urinary oxalates. As in man, the exogenous origin of urinary oxalates in cats is thought to be of minor importance, although the precise contribution of dietary oxalates remains unclear. The generally accepted dietary risk factors for CaOx urolithiasis in cats are discussed and a model for the biosynthetic pathways of oxalate in feline liver is provided. Alanine:glyoxylate aminotransferase 1 (AGT1) in endogenous oxalate metabolism is a liver-specific enzyme targeted in the mitochondria in cats, and allows for efficient conversion of glyoxylate to glycine when fed a carnivorous diet. The low peroxisomal activity of AGT1 in cat liver is compatible with the view that felids utilised a low-carbohydrate diet throughout evolution. Future research should focus on understanding de novo biosynthesis of oxalate in cats and their adaptation(s) in oxalate metabolism, and on dietary oxalate intake and absorption by cats.
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Peng JB. TRPV5 and TRPV6 in transcellular Ca(2+) transport: regulation, gene duplication, and polymorphisms in African populations. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:239-75. [PMID: 21290300 DOI: 10.1007/978-94-007-0265-3_14] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
TRPV5 and TRPV6 are unique members of the TRP super family. They are highly selective for Ca(2+) ions with multiple layers of Ca(2+)-dependent inactivation mechanisms, expressed at the apical membrane of Ca(2+) transporting epithelia, and robustly responsive to 1,25-dihydroxivitamin D(3). These features are well suited for their roles as Ca(2+) entry channels in the first step of transcellular Ca(2+) transport pathways, which are involved in intestinal absorption, renal reabsorption of Ca(2+), placental transfer of Ca(2+) to fetus, and many other processes. While TRPV6 is more broadly expressed in a variety of tissues such as esophagus, stomach, small intestine, colon, kidney, placenta, pancreas, prostate, uterus, salivary gland, and sweat gland, TRPV5 expression is relatively restricted to the distal convoluted tubule and connecting tubule of the kidney. There is only one TRPV6-like gene in fish and birds in comparison to both TRPV5 and TRPV6 genes in mammals, indicating TRPV5 gene was likely generated from duplication of TRPV6 gene during the evolution of mammals to meet the needs of complex renal function. TRPV5 and TRPV6 are subjected to vigorous regulations under physiological, pathological, and therapeutic conditions. The elevated TRPV6 level in malignant tumors such as prostate and breast cancers makes it a potential therapeutic target. TRPV6, and to a lesser extent TRPV5, exhibit unusually high levels of single nucleotide polymorphisms (SNPs) in African populations as compared to other populations, indicating TRPV6 gene was under selective pressure during or after humans migrated out of Africa. The SNPs of TRPV6 and TRPV5 likely contribute to the Ca(2+) conservation mechanisms in African populations.
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Affiliation(s)
- Ji-Bin Peng
- Division of Nephrology, Department of Medicine, Nephrology Research and Training Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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Damasio PCG, Amaro CRP, Berto SJP, Cunha NB, Pichutte AC, Padovani CR, Amaro JL. Urinary lithiasis and idiopathic hypercalciuria: the importance of dietary intake evaluation. Int Braz J Urol 2010; 36:557-62. [DOI: 10.1590/s1677-55382010000500005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2010] [Indexed: 11/22/2022] Open
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Taylor EN, Curhan GC. Demographic, dietary, and urinary factors and 24-h urinary calcium excretion. Clin J Am Soc Nephrol 2009; 4:1980-7. [PMID: 19820135 DOI: 10.2215/cjn.02620409] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND OBJECTIVES Higher urinary calcium is a risk factor for nephrolithiasis. This study delineated associations between demographic, dietary, and urinary factors and 24-h urinary calcium. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Cross-sectional studies were conducted of 2201 stone formers (SF) and 1167 nonstone formers (NSF) in the Health Professionals Follow-up Study (men) and Nurses' Health Studies I and II (older and younger women). RESULTS Median urinary calcium was 182 mg/d in men, 182 mg/d in older women, and 192 mg/d in younger women. Compared with NSF, urinary calcium as a fraction of calcium intake was 33 to 38% higher in SF (P values < or =0.01). In regression analyses, participants were combined because associations with urinary calcium were similar in each cohort and in SF and NSF. After multivariate adjustment, participants in the highest quartile of calcium intake excreted 18 mg/d more urinary calcium than those in the lowest (P trend =0.01). Caffeine and family history of nephrolithiasis were positively associated, whereas urinary potassium, thiazides, gout, and age were inversely associated, with urinary calcium. After multivariate adjustment, participants in the highest quartiles of urinary magnesium, sodium, sulfate, citrate, phosphorus, and volume excreted 71 mg/d, 37 mg/d, 44 mg/d, 61 mg/d, 37 mg/d, and 24 mg/d more urinary calcium, respectively, than participants in the lowest (P values trend < or =0.01). CONCLUSIONS Intestinal calcium absorption and/or negative calcium balance is greater in SF than NSF. Higher calcium intakes at levels typically observed in free-living individuals are associated with only small increases in urinary calcium.
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Affiliation(s)
- Eric N Taylor
- Renal Division and Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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Active Ca2+ reabsorption in the connecting tubule. Pflugers Arch 2008; 458:99-109. [DOI: 10.1007/s00424-008-0602-6] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Accepted: 10/08/2008] [Indexed: 10/21/2022]
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Thumfart J, Jung S, Amasheh S, Krämer S, Peters H, Sommer K, Biber J, Murer H, Meij I, Querfeld U, Wagner CA, Müller D. Magnesium stimulates renal phosphate reabsorption. Am J Physiol Renal Physiol 2008; 295:F1126-33. [DOI: 10.1152/ajprenal.00353.2007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In the kidney, ∼80% of the filtered phosphate (Pi) is reabsorbed along the proximal tubule. Changes in renal Pireabsorption are associated with modulation of the sodium-dependent Picotransporter type IIa (NaPi-IIa) and type IIc (NaPi-IIc) protein abundance in the brush-border membrane (BBM) of proximal tubule cells. NaPi-IIa is mainly regulated by dietary Piintake and parathyroid hormone (PTH). The purpose of the present study was to elucidate the effect of alteration in dietary magnesium (Mg2+) intake on renal Pihandling. Urinary Piexcretion and renal expression of NaPi-IIa and NaPi-IIc were analyzed in rats fed a normal (0.2%) or high-Mg2+(2.5%) diet. A high-Mg2+diet resulted in decreased renal Piexcretion and increased protein expression of NaPi-IIa and NaPi-IIc. Serum FGF-23 (fibroblast growth factor 23) levels were unchanged under a high-Mg2+diet. Serum PTH levels were slightly decreased under a high-Mg2+diet. To examine whether the observed changes in renal Pireabsorption are PTH dependent, expression of NaPi-IIa and NaPi-IIc was also analyzed in parathyroidectomized (PTX) rats fed a normal or high-Mg2+diet. In PTX rats, Mg2+had no significant effect on renal Piexcretion or NaPi-IIa protein expression. Mg2+increased NaPi-IIc protein expression in PTX rats. This experiment shows for the first time on the molecular level how Mg2+stimulates renal Pireabsorption. Under a high-Mg2+diet, NaPi-IIa expression is dependent on PTH levels, whereas NaPi-IIc expression seems to be independent of PTH levels.
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