1
|
Sukmak M, Kyaw TS, Nahok K, Sharma A, Silsirivanit A, Lert-itthiporn W, Japrung D, Pinlaor S, Anutrakulchai S, Selmi C, Slupsky CM, Hammock BD, Cha’on U. Urinary metabolic profile and its predictive indexes after MSG consumption in rat. PLoS One 2024; 19:e0309728. [PMID: 39226266 PMCID: PMC11371250 DOI: 10.1371/journal.pone.0309728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Accepted: 08/16/2024] [Indexed: 09/05/2024] Open
Abstract
Monosodium glutamate (MSG) is a widely used food additive with conflicting evidence regarding its potential effects on human health, with proposed relevance for obesity and metabolic syndrome (MetS) or chronic kidney disease. As being able to accurately quantify the MSG dietary intake would help clarify the open issues, we constructed a predictive formula to estimate the daily intake of MSG in a rat model based on the urinary metabolic profile. Adult male Wistar rats were divided into groups receiving different daily amounts of MSG in drinking water (0.5, 1.5, and 3.0 g%), no MSG, and MSG withdrawal after 3.0% MSG treatment for 4 weeks. We then analyzed 24-hour urine samples for chemistries and metabolites using 1H NMR spectrometry and observed a strong correlation between urine pH, sodium, bicarbonate, alpha-ketoglutarate, citrate, fumarate, glutamate, methylamine, N-methyl-4-pyridone-3-carboxamide, succinate, and taurine and the daily MSG intake. Following the multiple linear regression analysis a simple formula model based on urinary Na+, citrate, and glutamate was most accurate and could be validated for estimating daily MSG intake. In conclusion, we propose that the daily MSG intake correlates with urinary metabolites in a rat model and that this new tool for monitoring the impact of MSG on health measures.
Collapse
Affiliation(s)
- Manatsaphon Sukmak
- Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
- Chronic Kidney Disease prevention in the Northeast of Thailand (CKDNET), Khon Kaen University, Khon Kaen, Thailand
| | - Thin Su Kyaw
- Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
- Chronic Kidney Disease prevention in the Northeast of Thailand (CKDNET), Khon Kaen University, Khon Kaen, Thailand
| | - Kanokwan Nahok
- Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
- Chronic Kidney Disease prevention in the Northeast of Thailand (CKDNET), Khon Kaen University, Khon Kaen, Thailand
| | - Amod Sharma
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Atit Silsirivanit
- Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Worachart Lert-itthiporn
- Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
- Chronic Kidney Disease prevention in the Northeast of Thailand (CKDNET), Khon Kaen University, Khon Kaen, Thailand
| | - Deanpen Japrung
- National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), Thailand Science Park, Pathum Thani, Thailand
| | - Somchai Pinlaor
- Chronic Kidney Disease prevention in the Northeast of Thailand (CKDNET), Khon Kaen University, Khon Kaen, Thailand
- Department of Parasitology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Sirirat Anutrakulchai
- Chronic Kidney Disease prevention in the Northeast of Thailand (CKDNET), Khon Kaen University, Khon Kaen, Thailand
- Department of Internal Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Carlo Selmi
- Rheumatology and Clinical Immunology, IRCCS Humanitas Research Hospital, Rozzano, Milan, Italy
- Department of Biomedical Sciences, Humanitas University, Pieve Emanuele, Milan, Italy
| | - Carolyn M. Slupsky
- Department of Nutrition and Department of Food Science & Technology, University of California, Davis, CA, United States of America
| | - Bruce D. Hammock
- Department of Entomology & Nematology and the UC Davis Comprehensive Cancer Research Center, University of California, Davis, CA, United States of America
| | - Ubon Cha’on
- Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
- Chronic Kidney Disease prevention in the Northeast of Thailand (CKDNET), Khon Kaen University, Khon Kaen, Thailand
| |
Collapse
|
2
|
Wesson DE. The Importance of Recognizing and Addressing the Spectrum of Acid Stress. Adv Chronic Kidney Dis 2022; 29:364-372. [PMID: 36175074 DOI: 10.1053/j.ackd.2022.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 06/01/2022] [Accepted: 06/09/2022] [Indexed: 01/25/2023]
Abstract
Acid accumulation sufficient to reduce plasma bicarbonate concentration, thereby recognized as chronic metabolic acidosis, harms bones and muscles and appears to enhance progression of CKD. Evolving evidence supports that progressive acid accumulation that is not enough to cause chronic metabolic acidosis nevertheless has deleterious effects. Measurable acid retention without reduced plasma bicarbonate concentration, called eubicarbonatemic acidosis, also appears to cause kidney injury and exacerbate CKD progression. Furthermore, chronic engagement of mechanisms to mitigate the ongoing acid challenge of net acid-producing diets of developed societies also appears to be deleterious, including for kidney health. This review challenges clinicians to consider the growing evidence for a spectrum of acid-accumulation disorders that include lesser degrees of acid accumulation than metabolic acidosis yet are harmful. Further research will develop clinically useful tools to identify individuals suffering from these earlier stages of acid stress and determine if the straightforward and comparatively inexpensive intervention of dietary acid reduction relieves or eliminates the harm they appear to cause.
Collapse
Affiliation(s)
- Donald E Wesson
- The University of Texas at Austin Dell Medical School, Austin, TX; Donald E Wesson Consulting LLC, Dallas, TX.
| |
Collapse
|
3
|
Gołębiowski T, Kusztal M, Konieczny A, Kuriata-Kordek M, Gawryś A, Augustyniak-Bartosik H, Letachowicz K, Zielińska D, Wiśniewska M, Krajewska M. Exhausted Capacity of Bicarbonate Buffer in Renal Failure Diagnosed Using Point of Care Analyzer. Diagnostics (Basel) 2021; 11:diagnostics11020226. [PMID: 33546171 PMCID: PMC7913213 DOI: 10.3390/diagnostics11020226] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/28/2021] [Accepted: 01/30/2021] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Metabolic acidosis in patients with chronic kidney disease (CKD) is a common complication. A bicarbonate concentration in venous blood (V-HCO3-) is a key index for diagnosis and treatment initiation. The aim of our study is to evaluate usability of acid-base balance parameters of in blood taken simultaneously from peripheral artery and the vein. METHODS A total of 49 patients (median age 66 years [interquartile range IQR 45-75]), with CKD stage G4 or G5 were enrolled in this cross-sectional study. All patients were qualified for arteriovenous fistula creation in pre-dialysis period. The samples were taken during surgery, directly after dissection, and evaluated in a point of care testing analyzer. The arteriovenous difference in bicarbonate levels (Δ-HCO3-) was calculated. According to glomerular filtration rate (eGFR) the group was divided into Group A eGFR ≥ 10 mL/min/1.73 m2) and Group B eGFR < 10 mL/min/1.73 m2). RESULTS In Group A Δ-HCO3- was significantly higher compared to Group B. No such differences were observed in the case of V-HCO3-. Δ-HCO3- positively correlated with eGFR. The discriminative power of Δ-HCO3- for predicting eGFR < 10 mL/min/1.73 m2 was 0.72 (95% confidence interval [CI] = 0.551-0.88; p = 0.01) which provided 67% sensitivity and 75% specificity. The best cut-off was 0.5 mmol/L. CONCLUSIONS The Δ-HCO3- lower than 0.5 mmol/L may be used as predictor of exhaust buffer capacity. The value of this tool should be tested in larger population.
Collapse
Affiliation(s)
- Tomasz Gołębiowski
- Department of Nephrology and Transplantation Medicine, Wroclaw Medical University, 50-556 Wroclaw, Poland; (M.K.); (A.K.); (M.K.-K.); (A.G.); (H.A.-B.); (K.L.); (D.Z.); (M.K.)
- Correspondence:
| | - Mariusz Kusztal
- Department of Nephrology and Transplantation Medicine, Wroclaw Medical University, 50-556 Wroclaw, Poland; (M.K.); (A.K.); (M.K.-K.); (A.G.); (H.A.-B.); (K.L.); (D.Z.); (M.K.)
| | - Andrzej Konieczny
- Department of Nephrology and Transplantation Medicine, Wroclaw Medical University, 50-556 Wroclaw, Poland; (M.K.); (A.K.); (M.K.-K.); (A.G.); (H.A.-B.); (K.L.); (D.Z.); (M.K.)
| | - Magdalena Kuriata-Kordek
- Department of Nephrology and Transplantation Medicine, Wroclaw Medical University, 50-556 Wroclaw, Poland; (M.K.); (A.K.); (M.K.-K.); (A.G.); (H.A.-B.); (K.L.); (D.Z.); (M.K.)
| | - Ada Gawryś
- Department of Nephrology and Transplantation Medicine, Wroclaw Medical University, 50-556 Wroclaw, Poland; (M.K.); (A.K.); (M.K.-K.); (A.G.); (H.A.-B.); (K.L.); (D.Z.); (M.K.)
| | - Hanna Augustyniak-Bartosik
- Department of Nephrology and Transplantation Medicine, Wroclaw Medical University, 50-556 Wroclaw, Poland; (M.K.); (A.K.); (M.K.-K.); (A.G.); (H.A.-B.); (K.L.); (D.Z.); (M.K.)
| | - Krzysztof Letachowicz
- Department of Nephrology and Transplantation Medicine, Wroclaw Medical University, 50-556 Wroclaw, Poland; (M.K.); (A.K.); (M.K.-K.); (A.G.); (H.A.-B.); (K.L.); (D.Z.); (M.K.)
| | - Dorota Zielińska
- Department of Nephrology and Transplantation Medicine, Wroclaw Medical University, 50-556 Wroclaw, Poland; (M.K.); (A.K.); (M.K.-K.); (A.G.); (H.A.-B.); (K.L.); (D.Z.); (M.K.)
| | - Magdalena Wiśniewska
- Clinical Department of Nephrology, Transplantology and Internal Medicine, Pomeranian Medical University, 70-214 Szczecin, Poland;
| | - Magdalena Krajewska
- Department of Nephrology and Transplantation Medicine, Wroclaw Medical University, 50-556 Wroclaw, Poland; (M.K.); (A.K.); (M.K.-K.); (A.G.); (H.A.-B.); (K.L.); (D.Z.); (M.K.)
| |
Collapse
|
4
|
Onishi A, Fu Y, Patel R, Darshi M, Crespo-Masip M, Huang W, Song P, Freeman B, Kim YC, Soleimani M, Sharma K, Thomson SC, Vallon V. A role for tubular Na +/H + exchanger NHE3 in the natriuretic effect of the SGLT2 inhibitor empagliflozin. Am J Physiol Renal Physiol 2020; 319:F712-F728. [PMID: 32893663 DOI: 10.1152/ajprenal.00264.2020] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Inhibitors of proximal tubular Na+-glucose cotransporter 2 (SGLT2) are natriuretic, and they lower blood pressure. There are reports that the activities of SGLT2 and Na+-H+ exchanger 3 (NHE3) are coordinated. If so, then part of the natriuretic response to an SGLT2 inhibitor is mediated by suppressing NHE3. To examine this further, we compared the effects of an SGLT2 inhibitor, empagliflozin, on urine composition and systolic blood pressure (SBP) in nondiabetic mice with tubule-specific NHE3 knockdown (NHE3-ko) and wild-type (WT) littermates. A single dose of empagliflozin, titrated to cause minimal glucosuria, increased urinary excretion of Na+ and bicarbonate and raised urine pH in WT mice but not in NHE3-ko mice. Chronic empagliflozin treatment tended to lower SBP despite higher renal renin mRNA expression and lowered the ratio of SBP to renin mRNA, indicating volume loss. This effect of empagliflozin depended on tubular NHE3. In diabetic Akita mice, chronic empagliflozin enhanced phosphorylation of NHE3 (S552/S605), changes previously linked to lesser NHE3-mediated reabsorption. Chronic empagliflozin also increased expression of genes involved with renal gluconeogenesis, bicarbonate regeneration, and ammonium formation. While this could reflect compensatory responses to acidification of proximal tubular cells resulting from reduced NHE3 activity, these effects were at least in part independent of tubular NHE3 and potentially indicated metabolic adaptations to urinary glucose loss. Moreover, empagliflozin increased luminal α-ketoglutarate, which may serve to stimulate compensatory distal NaCl reabsorption, while cogenerated and excreted ammonium balances urine losses of this "potential bicarbonate." The data implicate NHE3 as a determinant of the natriuretic effect of empagliflozin.
Collapse
Affiliation(s)
- Akira Onishi
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Yiling Fu
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Rohit Patel
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Manjula Darshi
- Center for Renal Precision Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Maria Crespo-Masip
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California.,Biomedical Research Institute, University of Lleida, Lleida, Spain
| | - Winnie Huang
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Panai Song
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Brent Freeman
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Young Chul Kim
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | | | - Kumar Sharma
- Center for Renal Precision Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Scott Culver Thomson
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Volker Vallon
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| |
Collapse
|
5
|
Monosodium Glutamate (MSG) Renders Alkalinizing Properties and Its Urinary Metabolic Markers of MSG Consumption in Rats. Biomolecules 2019; 9:biom9100542. [PMID: 31569818 PMCID: PMC6843139 DOI: 10.3390/biom9100542] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 09/25/2019] [Accepted: 09/26/2019] [Indexed: 12/12/2022] Open
Abstract
Monosodium glutamate (MSG) is widely used as a flavor enhancer and its effects on human health are still debated. We aimed to investigate whether MSG can act as alkalinizing agent in murine models and if its metabolites are biomarkers of MSG consumption. For this purpose, adult male Wistar rats were given water added with 1 g% MSG or three types of control water, including sodium chloride (NaCl) and sodium bicarbonate (NaHCO3). At 14 days, urinary pH, electrolytes, urinary metabolites and ion-exchanger gene expression were determined. The results revealed that MSG-treated rats had significantly more alkaline urine and higher levels of urinary sodium and bicarbonate similar to NaHCO3 controls. These changes correlated with a lower expression of ion-exchanger genes, namely, CAII, NBC1, and AE1, which are involved in bicarbonate kidney reabsorption. The urinary metabolic profiles also revealed similar patterns for the MSG and NaHCO3 groups. In conclusion, MSG exhibits similar properties to NaHCO3, an alkalinizing agent, with regard to inducing alkaline urine, reducing bicarbonate kidney reabsorption, and generating a specific urinary metabolic pattern. We believe that these observations will be useful to further study the MSG effects in humans.
Collapse
|
6
|
Whittamore JM, Hatch M. Oxalate transport by the mouse intestine in vitro is not affected by chronic challenges to systemic acid-base homeostasis. Urolithiasis 2018; 47:243-254. [PMID: 29947993 DOI: 10.1007/s00240-018-1067-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 06/10/2018] [Indexed: 12/15/2022]
Abstract
In rats, we recently showed how a chronic metabolic acidosis simultaneously reduced urinary oxalate excretion and promoted oxalate secretion by the distal colon leading to the proposition that acid-base disturbances may trigger changes to renal and intestinal oxalate handling. The present study sought to reproduce and extend these observations using the mouse model, where the availability of targeted gene knockouts (KOs) would offer future opportunities to reveal some of the underlying transporters and mechanisms involved. Mice were provided with a sustained load of acid (NH4Cl), base (NaHCO3) or the carbonic anhydrase inhibitor acetazolamide (ATZ) for 7 days after which time the impacts on urinary oxalate excretion and its transport by the intestine were evaluated. Mice consuming NH4Cl developed a metabolic acidosis but urinary oxalate was only reduced 46% and not statistically different from the control group, while provision of NaHCO3 provoked a significant 2.6-fold increase in oxalate excretion. For mice receiving ATZ, the rate of urinary oxalate excretion did not change significantly. Critically, none of these treatments altered the fluxes of oxalate (or chloride) across the distal ileum, cecum or distal colon. Hence, we were unable to produce the same effects of a metabolic acidosis in mice that we had previously found in rats, failing to find any evidence of the 'gut-kidney axis' influencing oxalate handling in response to various acid-base challenges. Despite the potential advantages offered by KO mice, this model species is not suitable for exploring how acid-base status regulates oxalate handling between the kidney and intestine.
Collapse
Affiliation(s)
- Jonathan M Whittamore
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, PO Box 100275, 1600 SW Archer Rd, Gainesville, FL, 32610, USA.
| | - Marguerite Hatch
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, PO Box 100275, 1600 SW Archer Rd, Gainesville, FL, 32610, USA
| |
Collapse
|
7
|
Scialla JJ, Asplin J, Dobre M, Chang AR, Lash J, Hsu CY, Kallem RR, Hamm LL, Feldman HI, Chen J, Appel LJ, Anderson CAM, Wolf M. Higher net acid excretion is associated with a lower risk of kidney disease progression in patients with diabetes. Kidney Int 2017; 91:204-215. [PMID: 27914710 PMCID: PMC5518613 DOI: 10.1016/j.kint.2016.09.012] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 09/01/2016] [Accepted: 09/08/2016] [Indexed: 01/14/2023]
Abstract
Higher diet-dependent nonvolatile acid load is associated with faster chronic kidney disease (CKD) progression, but most studies have used estimated acid load or measured only components of the gold standard, net acid excretion (NAE). Here we measured NAE as the sum of urine ammonium and titratable acidity in 24-hour urines from a random subset of 980 participants in the Chronic Renal Insufficiency Cohort (CRIC) Study. In multivariable models accounting for demographics, comorbidity and kidney function, higher NAE was significantly associated with lower serum bicarbonate (0.17 mEq/l lower serum bicarbonate per 10 mEq/day higher NAE), consistent with a larger acid load. Over a median of 6 years of follow-up, higher NAE was independently associated with a significantly lower risk of the composite of end-stage renal disease or halving of estimated glomerular filtration rate among diabetics (hazard ratio 0.88 per 10 mEq/day higher NAE), but not those without diabetes (hazard ratio 1.04 per 10 mEq/day higher NAE). For comparison, we estimated the nonvolatile acid load as net endogenous acid production using self-reported food frequency questionnaires from 2848 patients and dietary urine biomarkers from 3385 patients. Higher net endogenous acid production based on biomarkers (urea nitrogen and potassium) was modestly associated with faster CKD progression consistent with prior reports, but only among those without diabetes. Results from the food frequency questionnaires were not associated with CKD progression in any group. Thus, disparate results obtained from analyses of nonvolatile acid load directly measured as NAE and estimated from diet suggest a novel hypothesis that the risk of CKD progression related to low NAE or acid load may be due to diet-independent changes in acid production in diabetes.
Collapse
Affiliation(s)
- Julia J Scialla
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA; Duke Clinical Research Institute, Duke University School of Medicine, Durham, North Carolina, USA; Department of Medicine, Durham Veterans Affairs Medical Center, Durham, North Carolina, USA.
| | - John Asplin
- Litholink Corp, Laboratory Corporation of America Holdings, Chicago, Illinois, USA
| | - Mirela Dobre
- Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Alex R Chang
- Kidney Health Research Institute, Geisinger Health System, Danville, Pennsylvania, USA
| | - James Lash
- Department of Medicine, University of Illinois Chicago, Chicago, Illinois, USA
| | - Chi-Yuan Hsu
- Department of Medicine, University of California, San Francisco, San Francisco, California, USA; Division of Research, Kaiser Permanente Northern California, Oakland, California, USA
| | - Radhakrishna R Kallem
- Department of Biostatistics and Epidemiology and the Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - L Lee Hamm
- Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana, USA
| | - Harold I Feldman
- Department of Biostatistics and Epidemiology and the Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jing Chen
- Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana, USA
| | - Lawrence J Appel
- Department of Medicine, Johns Hopkins University School of Medicine and The Welch Center for Prevention, Epidemiology and Clinical Research, Baltimore, Maryland, USA
| | - Cheryl A M Anderson
- Department of Family Medicine and Public Health, University of California San Diego, San Diego, California, USA
| | - Myles Wolf
- Division of Nephrology and Hypertension, Department of Medicine, and Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| |
Collapse
|
8
|
Osis G, Handlogten ME, Lee HW, Hering-Smith KS, Huang W, Romero MF, Verlander JW, Weiner ID. Effect of NBCe1 deletion on renal citrate and 2-oxoglutarate handling. Physiol Rep 2016; 4:e12778. [PMID: 27117802 PMCID: PMC4848728 DOI: 10.14814/phy2.12778] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 03/29/2016] [Accepted: 04/01/2016] [Indexed: 12/03/2022] Open
Abstract
UNLABELLED The bicarbonate transporter, NBCe1 (SLC4A4), is necessary for at least two components of the proximal tubule contribution to acid-base homeostasis, filtered bicarbonate reabsorption, and ammonia metabolism. This study's purpose was to determine NBCe1's role in a third component of acid-base homeostasis, organic anion metabolism, by studying mice with NBCe1 deletion. Because NBCe1 deletion causes metabolic acidosis, we also examined acid-loaded wild-type adult mice to determine if the effects of NBCe1 deletion were specific to NBCe1 deletion or were a non-specific effect of the associated metabolic acidosis. Both NBCe1 KO and acid-loading decreased citrate excretion, but in contrast to metabolic acidosis alone, NBCe1 KO decreased expression of the apical citrate transporter, NaDC-1. Thus, NBCe1 expression is necessary for normal NaDC-1 expression, and NBCe1 deletion induces a novel citrate reabsorptive pathway. Second, NBCe1 KO increased 2-oxoglutarate excretion. This could not be attributed to the metabolic acidosis as experimental acidosis decreased excretion. Increased 2-oxoglutarate excretion could not be explained by changes in plasma 2-oxoglutarate levels, the glutaminase I or the glutaminase II generation pathways, 2-oxoglutarate metabolism, its putative apical 2-oxoglutarate transporter, OAT10, or its basolateral transporter, NaDC-3. IN SUMMARY (1) NBCe1 is necessary for normal proximal tubule NaDC-1 expression; (2) NBCe1 deletion results in stimulation of a novel citrate reabsorptive pathway; and (3) NBCe1 is necessary for normal 2-oxoglutarate metabolism through mechanisms independent of expression of known transport and metabolic pathways.
Collapse
Affiliation(s)
- Gunars Osis
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Mary E Handlogten
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Hyun-Wook Lee
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | | | - Weitao Huang
- Renal Division, Tulane University College of Medicine, New Orleans, Louisiana
| | - Michael F Romero
- Department of Physiology & Biomedical Engineering and Nephrology & Hypertension, Mayo Clinic College Of Medicine, Rochester, Minnesota
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - I David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, Florida
| |
Collapse
|
9
|
Kraut JA, Madias NE. Metabolic Acidosis of CKD: An Update. Am J Kidney Dis 2015; 67:307-17. [PMID: 26477665 DOI: 10.1053/j.ajkd.2015.08.028] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 08/01/2015] [Indexed: 01/02/2023]
Abstract
The kidney has the principal role in the maintenance of acid-base balance. Therefore, a decrease in renal ammonium excretion and a positive acid balance often leading to a reduction in serum bicarbonate concentration are observed in the course of chronic kidney disease (CKD). The decrease in serum bicarbonate concentration is usually absent until glomerular filtration rate decreases to <20 to 25mL/min/1.73 m(2), although it can develop with lesser degrees of decreased kidney function. Non-anion gap acidosis, high-anion gap acidosis, or both can be found at all stages of CKD. The acidosis can be associated with muscle wasting, bone disease, hypoalbuminemia, inflammation, progression of CKD, and increased mortality. Administration of base may decrease muscle wasting, improve bone disease, and slow the progression of CKD. Base is suggested when serum bicarbonate concentration is <22 mEq/L, but the target serum bicarbonate concentration is unclear. Evidence that increments in serum bicarbonate concentration > 24 mEq/L might be associated with worsening of cardiovascular disease adds complexity to treatment decisions. Further study of the mechanisms through which metabolic acidosis contributes to the progression of CKD, as well as the pathways involved in mediating the benefits and complications of base therapy, is warranted.
Collapse
Affiliation(s)
- Jeffrey A Kraut
- Medical and Research Services, VHAGLA Healthcare System, UCLA Membrane Biology Laboratory, Los Angeles, CA; Division of Nephrology, VHAGLA Healthcare System and David Geffen School of Medicine, Los Angeles, CA.
| | - Nicolaos E Madias
- Department of Medicine, Division of Nephrology, St. Elizabeth's Medical Center, Boston, MA; Department of Medicine, Tufts University School of Medicine, Boston, MA.
| |
Collapse
|
10
|
Abstract
The H(+) concentration in human blood is kept within very narrow limits, ~40 nmol/L, despite the fact that dietary metabolism generates acid and base loads that are added to the systemic circulation throughout the life of mammals. One of the primary functions of the kidney is to maintain the constancy of systemic acid-base chemistry. The kidney has evolved the capacity to regulate blood acidity by performing three key functions: (i) reabsorb HCO3(-) that is filtered through the glomeruli to prevent its excretion in the urine; (ii) generate a sufficient quantity of new HCO3(-) to compensate for the loss of HCO3(-) resulting from dietary metabolic H(+) loads and loss of HCO3(-) in the urea cycle; and (iii) excrete HCO3(-) (or metabolizable organic anions) following a systemic base load. The ability of the kidney to perform these functions requires that various cell types throughout the nephron respond to changes in acid-base chemistry by modulating specific ion transport and/or metabolic processes in a coordinated fashion such that the urine and renal vein chemistry is altered appropriately. The purpose of the article is to provide the interested reader with a broad review of a field that began historically ~60 years ago with whole animal studies, and has evolved to where we are currently addressing questions related to kidney acid-base regulation at the single protein structure/function level.
Collapse
Affiliation(s)
- Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, Los Angeles, CA; Brain Research Institute, UCLA, Los Angeles, CA
| |
Collapse
|
11
|
Tokonami N, Morla L, Centeno G, Mordasini D, Ramakrishnan SK, Nikolaeva S, Wagner CA, Bonny O, Houillier P, Doucet A, Firsov D. α-Ketoglutarate regulates acid-base balance through an intrarenal paracrine mechanism. J Clin Invest 2013; 123:3166-71. [PMID: 23934124 DOI: 10.1172/jci67562] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 04/11/2013] [Indexed: 12/11/2022] Open
Abstract
Paracrine communication between different parts of the renal tubule is increasingly recognized as an important determinant of renal function. Previous studies have shown that changes in dietary acid-base load can reverse the direction of apical α-ketoglutarate (αKG) transport in the proximal tubule and Henle's loop from reabsorption (acid load) to secretion (base load). Here we show that the resulting changes in the luminal concentrations of αKG are sensed by the αKG receptor OXGR1 expressed in the type B and non-A-non-B intercalated cells of the connecting tubule (CNT) and the cortical collecting duct (CCD). The addition of 1 mM αKG to the tubular lumen strongly stimulated Cl(-)-dependent HCO(3)(-) secretion and electroneutral transepithelial NaCl reabsorption in microperfused CCDs of wild-type mice but not Oxgr1(-/-) mice. Analysis of alkali-loaded mice revealed a significantly reduced ability of Oxgr1(-/-) mice to maintain acid-base balance. Collectively, these results demonstrate that OXGR1 is involved in the adaptive regulation of HCO(3)(-) secretion and NaCl reabsorption in the CNT/CCD under acid-base stress and establish αKG as a paracrine mediator involved in the functional coordination of the proximal and the distal parts of the renal tubule.
Collapse
Affiliation(s)
- Natsuko Tokonami
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Scialla JJ, Anderson CAM. Dietary acid load: a novel nutritional target in chronic kidney disease? Adv Chronic Kidney Dis 2013; 20:141-9. [PMID: 23439373 PMCID: PMC3604792 DOI: 10.1053/j.ackd.2012.11.001] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 11/06/2012] [Accepted: 11/12/2012] [Indexed: 02/07/2023]
Abstract
Nonvolatile acid is produced from the metabolism of organic sulfur in dietary protein and the production of organic anions during the combustion of neutral foods. Organic anion salts that are found primarily in plant foods are directly absorbed in the gastrointestinal tract and yield bicarbonate. The difference between endogenously produced nonvolatile acid and absorbed alkali precursors yields the dietary acid load, technically known as the net endogenous acid production, and must be excreted by the kidney to maintain acid-base balance. Although typically 1 mEq/kg/day, dietary acid load is lower with greater intake of fruits and vegetables. In the setting of CKD, a high dietary acid load invokes adaptive mechanisms to increase acid excretion despite reduced nephron number, such as increased per nephron ammoniagenesis and augmented distal acid excretion mediated by the renin-angiotensin system and endothelin-1. These adaptations may promote kidney injury. Additionally, high dietary acid loads produce low-grade, subclinical acidosis that may result in bone and muscle loss. Early studies suggest that lowering the dietary acid load can improve subclinical acidosis, preserve bone and muscle, and slow the decline of glomerular filtration rate in animal models and humans. Studies focusing on hard clinical outcomes are needed.
Collapse
Affiliation(s)
- Julia J Scialla
- Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
| | | |
Collapse
|
13
|
Poupin N, Calvez J, Lassale C, Chesneau C, Tomé D. Impact of the diet on net endogenous acid production and acid-base balance. Clin Nutr 2012; 31:313-21. [PMID: 22342140 DOI: 10.1016/j.clnu.2012.01.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 01/10/2012] [Accepted: 01/25/2012] [Indexed: 11/26/2022]
Abstract
Net acid production, which is composed of volatile acids (15,000 mEq/day) and metabolic acids (70-100 mEq/day) is relatively small compared to whole-body H⁺ turnover (150,000 mEq/day). Metabolic acids are ingested from the diet or produced as intermediary or end products of endogenous metabolism. The three commonly reported sources of net acid production are the metabolism of sulphur amino acids, the metabolism or ingestion of organic acids, and the metabolism of phosphate esters or dietary phosphoproteins. Net base production occurs mainly as a result of absorption of organic anions from the diet. To maintain acid-base balance, ingested and endogenously produced acids are neutralized within the body by buffer systems or eliminated from the body through the respiratory (excretion of volatile acid in the form of CO₂) and urinary (excretion of fixed acids and remaining H⁺) pathways. Because of the many reactions involved in the acid-base balance, the direct determination of acid production is complex and is usually estimated through direct or indirect measurements of acid excretion. However, indirect approaches, which assess the acid-forming potential of the ingested diet based on its composition, do not take all the acid-producing reactions into account. Direct measurements therefore seem more reliable. Nevertheless, acid excretion does not truly provide information on the way acidity is dealt with in the plasma and this measurement should be interpreted with caution when assessing acid-base imbalance.
Collapse
Affiliation(s)
- Nathalie Poupin
- AgroParisTech, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, 16 rue Claude Bernard, F-75005 Paris, France
| | | | | | | | | |
Collapse
|
14
|
A comprehensive analysis of gene expression profiles in distal parts of the mouse renal tubule. Pflugers Arch 2010; 460:925-52. [PMID: 20686783 DOI: 10.1007/s00424-010-0863-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 07/05/2010] [Accepted: 07/05/2010] [Indexed: 12/11/2022]
Abstract
The distal parts of the renal tubule play a critical role in maintaining homeostasis of extracellular fluids. In this review, we present an in-depth analysis of microarray-based gene expression profiles available for microdissected mouse distal nephron segments, i.e., the distal convoluted tubule (DCT) and the connecting tubule (CNT), and for the cortical portion of the collecting duct (CCD; Zuber et al., Proc Natl Acad Sci USA 106:16523-16528, 2009). Classification of expressed transcripts in 14 major functional gene categories demonstrated that all principal proteins involved in maintaining the salt and water balance are represented by highly abundant transcripts. However, a significant number of transcripts belonging, for instance, to categories of G-protein-coupled receptors or serine/threonine kinases exhibit high expression levels but remain unassigned to a specific renal function. We also established a list of genes differentially expressed between the DCT/CNT and the CCD. This list is enriched by genes related to segment-specific transport functions and by transcription factors directing the development of the distal nephron or collecting ducts. Collectively, this in silico analysis provides comprehensive information about relative abundance and tissue specificity of the DCT/CNT and the CCD expressed transcripts and identifies new candidate genes for renal homeostasis.
Collapse
|
15
|
Stratton-Phelps M, House JK. Effect of a commercial anion dietary supplement on acid-base balance, urine volume, and urinary ion excretion in male goats fed oat or grass hay diets. Am J Vet Res 2004; 65:1391-7. [PMID: 15524326 DOI: 10.2460/ajvr.2004.65.1391] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine whether feeding a commercial anionic dietary supplement as a urinary acidifier to male goats may be useful for management of urolithiasis. ANIMALS 8 adult sexually intact male Toggenburg, Saanen, and Nubian goats. PROCEDURE Goats were randomly assigned by age-, breed-, and weight-matched pairs to an oat or grass hay diet that was fed for 12 days. On days 13 to 14 (early sample collection time before supplementation), measurements were made of blood and urine sodium, potassium, calcium, magnesium, chloride, phosphorus, and sulfur concentrations; blood and urine pH; urine production; and water consumption. During the next 28 days, the anionic dietary supplement was added to the oat and grass hay diets to achieve a dietary cation-anion difference of 0 mEq/100g of dry matter. Blood and urine samples were analyzed during dietary supplementation on days 12 to 13 (middle sample collection time) and 27 to 28 (late sample collection time). RESULTS Blood bicarbonate, pH, and urine pH of goats fed grass hay and goats fed oat hay were significantly decreased during the middle and late sample collection times, compared with the early sample collection time. Water consumption and urine production in all goats increased significantly during the late sample collection time, compared with the early sample collection time. CONCLUSIONS AND CLINICAL RELEVANCE The anionic dietary supplement used in our study increases urine volume, alters urine ion concentrations, and is an efficacious urinary acidifier in goats. Goats treated with prolonged anionic dietary supplementation should be monitored for secondary osteoporosis from chronic urinary calcium loss.
Collapse
Affiliation(s)
- Meri Stratton-Phelps
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | | |
Collapse
|
16
|
Abstract
The sources and rates of metabolic acid production in relation to renal net acid excretion and thus acid balance in humans have remained controversial. The techniques and possible errors in these measurements are reviewed, as is the relationship of charge balance to acid balance. The results demonstrate that when acid production is experimentally increased among healthy subjects, renal net acid excretion does not increase as much as acid production so that acid balances become positive. These positive imbalances are accompanied by equivalently negative charge balances that are the result of bone buffering of retained H+ and loss of bone Ca2+ into the urine. The data also demonstrate that when acid production is experimentally reduced during the administration of KHCO3, renal net acid excretion does not decrease as much as the decrease in acid production so that acid balances become negative, or, in opposite terms, there are equivalently positive HCO3- balances. Equivalently positive K+ and Ca2+ balances, and thus positive charge balances, accompany these negative acid imbalances. Similarly, positive Na+ balances, and thus positive charge balances, accompany these negative acid balances during the administration of NaHCO3. These charge balances are likely the result of the adsorption of HCO3- onto the crystal surfaces of bone mineral. There do not appear to be significant errors in the measurements.
Collapse
Affiliation(s)
- Jacob Lemann
- Nephrology Section, Tulane University School of Medicine, 2601 St. Charles Ave., New Orleans, LA 70130-5927, USA.
| | | | | |
Collapse
|
17
|
Cheema-Dhadli S, Lin SH, Halperin ML. Mechanisms used to dispose of progressively increasing alkali load in rats. Am J Physiol Renal Physiol 2002; 282:F1049-55. [PMID: 11997321 DOI: 10.1152/ajprenal.00006.2001] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Our objective was to describe the process of alkali disposal in rats. Balance studies were performed while incremental loads of alkali were given to rats fed a low-alkali diet or their usual alkaline ash diet. Control groups received equimolar NaCl or KCl. Virtually all of the alkali was eliminated within 24 h when the dose exceeded 750 micromol. The most sensitive response to alkali input was a decline in the excretion of NH(4)(+). The next level of response was to increase the excretion of unmeasured anions; this rise was quantitatively the most important process in eliminating alkali. The maximum excretion of citrate was approximately 70% of its filtered load. An even higher alkali load augmented the excretion of 2-oxoglutarate to >400% of its filtered load. Only with the largest alkali load did bicarbonaturia become quantitatively important. We conclude that renal mechanisms eliminate alkali while minimizing bicarbonaturia. This provides a way of limiting changes in urine pH without sacrificing acid-base balance, a process that might lessen the risk of kidney stone formation.
Collapse
Affiliation(s)
- Surinder Cheema-Dhadli
- Renal Division, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada M5B 1A6
| | | | | |
Collapse
|
18
|
Lin SH, Cheema-Dhadli S, Chayaraks S, Chen CB, Gowrishankar M, Halperin ML. Physiological disposal of the potential alkali load in diet of the rat: steps to achieve acid-base balance. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:F1037-44. [PMID: 9841494 DOI: 10.1152/ajprenal.1998.274.6.f1037] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to provide a better understanding of the physiological role of endogenous net organic acid production in rats consuming their usual diet. Balance studies were performed over 24 h, and urine was collected in the day and night portions of the diurnal cycle. A supplemented low-electrolyte diet(LED) was fed to determine whether urinary organic anions were identical to those in the diet. A titration procedure was developed to determine the pK of titratable groups in the urine of rats studied with and without an acid load. Although normal rats excreted net acid (NAE), the latter was inversely related to the amount of food consumed. The rates of excretion of bicarbonate (HCO3), citrate, unmeasured organic anions, and NH+4 were higher in the night portion of the diurnal cycle. NAE rose dramatically when alkali intake was decreased by consuming the LED. Dietary and urinary organic anions were not identical because rats fed the LED supplemented with potassium citrate excreted <10% of this alkali load as citrate and <25% as HCO3. In the 24 h after 3,000 ¿mol NH4Cl was given intraperitoneally, H+ did not appear to be retained, yet NAE rose by only close to 2,000 ¿eq. The rate of excretion of titratable groups with a pK in the 3 to 5 pH range fell by close to 1,000 ¿eq; most of these changes occurred in the first 7 h after NH4Cl was given. We conclude that rat chow provides a large net alkali load. There appear to be two types of endogenous acid production, a form associated with a rise in NAE (e.g., sulfuric acid) and dietary alkali-driven endogenous net acid production, which titrates this alkali. Renal excretion of organic anions makes these acids end products of metabolism.
Collapse
Affiliation(s)
- S H Lin
- Renal Division, Tri-Service General Hospital, National Defense Medical Center, Taipei, Republic of China
| | | | | | | | | | | |
Collapse
|
19
|
Cohen RM, Feldman GM, Fernandez PC. The balance of acid, base and charge in health and disease. Kidney Int 1997; 52:287-93. [PMID: 9263983 DOI: 10.1038/ki.1997.334] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- R M Cohen
- Nephrology Division, Graduate Hospital, Allegheny University of the Health Sciences, Philadelphia, Pennsylvania, USA
| | | | | |
Collapse
|
20
|
|