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Yang TY, Lin HM, Wang HY, Chuang MH, Hsieh CC, Tsai KT, Chen JY. Sodium Bicarbonate Treatment and Clinical Outcomes in Chronic Kidney Disease with Metabolic Acidosis: A Meta-Analysis. Clin J Am Soc Nephrol 2024; 19:959-969. [PMID: 38980732 PMCID: PMC11321727 DOI: 10.2215/cjn.0000000000000487] [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: 12/26/2023] [Accepted: 06/11/2024] [Indexed: 07/11/2024]
Abstract
Key Points Sodium bicarbonate for patients with CKD and metabolic acidosis leads to a significant improvement in kidney function. Treatment with sodium bicarbonate increases in mid-arm muscle circumference, indicating a positive effect on enhancing muscle mass. Sodium bicarbonate supplementation is associated with a higher risk of elevated systolic BP, marking a potential side effect. Background In patients with CKD, impaired kidney acid excretion leads to the onset of metabolic acidosis (MA). However, the evidence is not yet conclusive regarding the effects of sodium bicarbonate in treating CKD with MA. Methods Databases with PubMed, Embase, and the Cochrane Library were used to search for randomized controlled trials (RCTs) from the inception until November 11, 2023, to identify RCTs investigating the effect of sodium bicarbonate in participants with CKD and MA. The primary outcome was the change in eGFR. Secondary outcomes included hospitalization rates, change in systolic BP, all-cause mortality, and mid-arm muscle circumference. A random-effects model was applied for analysis, and subgroup, sensitivity analyses were also performed. Results Fourteen RCTs comprising 2037 patients demonstrated that sodium bicarbonate supplementation significantly improved eGFR (standardized mean difference [SMD], 0.33; 95% confidence interval [CI], 0.03 to 0.63; P = 0.03). The group receiving sodium bicarbonate had a lower hospitalization rate (odds ratio, 0.37; 95% CI, 0.25 to 0.55; P < 0.001). Higher mid-arm muscle circumference was observed with sodium bicarbonate treatment compared with those without (SMD, 0.23; 95% CI, 0.08 to 0.38; P = 0.003, I2<0.001). However, higher risk of elevated systolic BP was found with sodium bicarbonate treatment (SMD, 0.10; 95% CI, 0.01 to 0.20; P = 0.03). No significant difference in all-cause mortality was noted. Conclusions In patients with CKD and MA, sodium bicarbonate supplementation may provide potential benefits in preventing the deterioration of kidney function and increasing muscle mass. However, treatment may be associated with higher BP. Owing to the risk of bias stemming from the absence of double-blinded designs and inconsistencies in control group definitions across the studies, further research is crucial to verify these findings.
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Affiliation(s)
- Ting-Ya Yang
- Department of Family Medicine, Chi Mei Medical Center, Tainan, Taiwan
| | - Hong-Min Lin
- Department of Family Medicine, Chi Mei Medical Center, Tainan, Taiwan
| | - Hsien-Yi Wang
- Division of Nephrology, Department of Internal Medicine, Chi-Mei Medical Center, Tainan, Taiwan
- Department of Sport Management, College of Leisure and Recreation Management, Chia Nan University of Pharmacy and Science, Tainan, Taiwan
| | - Min-Hsiang Chuang
- Division of Nephrology, Department of Internal Medicine, Chi-Mei Medical Center, Tainan, Taiwan
| | - Chia-Chen Hsieh
- Department of Family Medicine, Chi Mei Medical Center, Tainan, Taiwan
| | - Kang-Ting Tsai
- Department of Family Medicine, Chi Mei Medical Center, Tainan, Taiwan
- Department of Senior Welfare and Services, Southern Taiwan University of Science and Technology, Tainan, Taiwan
| | - Jui-Yi Chen
- Division of Nephrology, Department of Internal Medicine, Chi-Mei Medical Center, Tainan, Taiwan
- Department of Health and Nutrition, Chia Nan University of Pharmacy and Science, Tainan, Taiwan
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Arkhipov SN, Liao TD, Potter DL, Bobbitt KR, Ivanov V, Ortiz PA, Pavlov TS. Dissociation of Hypertension and Renal Damage After Cessation of High-Salt Diet in Dahl Rats. Hypertension 2024; 81:1345-1355. [PMID: 38618734 PMCID: PMC11096017 DOI: 10.1161/hypertensionaha.123.21887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 03/29/2024] [Indexed: 04/16/2024]
Abstract
BACKGROUND Every year, thousands of patients with hypertension reduce salt consumption in an effort to control their blood pressure. However, hypertension has a self-sustaining character in a significant part of the population. We hypothesized that chronic hypertension leads to irreversible renal damage that remains after removing the trigger, causing an elevation of the initial blood pressure. METHODS Dahl salt-sensitive rat model was used for chronic, continuous observation of blood pressure. Rats were fed a high salt diet to induce hypertension, and then the diet was switched back to normal sodium content. RESULTS We found that developed hypertension was irreversible by salt cessation: after a short period of reduction, blood pressure grew even higher than in the high-salt phase. Notably, the self-sustaining phase of hypertension was sensitive to benzamil treatment due to sustaining epithelial sodium channel hyperactivity, as shown with patch-clamp analysis. Glomerular damage and proteinuria were also irreversible. In contrast, some mechanisms, contributing to the development of salt-sensitive hypertension, normalized after salt restriction. Thus, flow cytometry demonstrated that dietary salt reduction in hypertensive animals decreased the number of total CD45+, CD3+CD4+, and CD3+CD8+ cells in renal tissues. Also, we found tubular recovery and improvement of glomerular filtration rate in the postsalt period versus a high-salt diet. CONCLUSIONS Based on earlier publications and current data, poor response to salt restriction is due to the differential contribution of the factors recognized in the developmental phase of hypertension. We suggest that proteinuria or electrolyte transport can be prioritized over therapeutic targets of inflammatory response.
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Affiliation(s)
- Sergey N. Arkhipov
- Division of Hypertension and Vascular Research, Henry Ford Health
- Department of Physiology, Wayne State University
| | - Tang-Dong Liao
- Division of Hypertension and Vascular Research, Henry Ford Health
| | - D'Anna L. Potter
- Division of Hypertension and Vascular Research, Henry Ford Health
| | | | - Veniamin Ivanov
- Division of Hypertension and Vascular Research, Henry Ford Health
| | - Pablo A. Ortiz
- Division of Hypertension and Vascular Research, Henry Ford Health
- Department of Physiology, Wayne State University
| | - Tengis S. Pavlov
- Division of Hypertension and Vascular Research, Henry Ford Health
- Department of Physiology, Wayne State University
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3
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Alvarez MR, Alkaissi H, Rieger AM, Esber GR, Acosta ME, Stephenson SI, Maurice AV, Valencia LMR, Roman CA, Alarcon JM. The immunomodulatory effect of oral NaHCO 3 is mediated by the splenic nerve: multivariate impact revealed by artificial neural networks. J Neuroinflammation 2024; 21:79. [PMID: 38549144 PMCID: PMC10976719 DOI: 10.1186/s12974-024-03067-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Accepted: 03/18/2024] [Indexed: 04/02/2024] Open
Abstract
Stimulation of the inflammatory reflex (IR) is a promising strategy for treating systemic inflammatory disorders. Recent studies suggest oral sodium bicarbonate (NaHCO3) as a potential activator of the IR, offering a safe and cost-effective treatment approach. However, the mechanisms underlying NaHCO3-induced anti-inflammatory effects remain unclear. We investigated whether oral NaHCO3's immunomodulatory effects are mediated by the splenic nerve. Female rats received NaHCO3 or water (H2O) for four days, and splenic immune markers were assessed using flow cytometry. NaHCO3 led to a significant increase (p < 0.05, and/or partial eta squared > 0.06) in anti-inflammatory markers, including CD11bc + CD206 + (M2-like) macrophages, CD3 + CD4 + FoxP3 + cells (Tregs), and Tregs/M1-like ratio. Conversely, proinflammatory markers, such as CD11bc + CD38 + TNFα + (M1-like) macrophages, M1-like/M2-like ratio, and SSChigh/SSClow ratio of FSChighCD11bc + cells, decreased in the spleen following NaHCO3 administration. These effects were abolished in spleen-denervated rats, suggesting the necessity of the splenic nerve in mediating NaHCO3-induced immunomodulation. Artificial neural networks accurately classified NaHCO3 and H2O treatment in sham rats but failed in spleen-denervated rats, highlighting the splenic nerve's critical role. Additionally, spleen denervation independently influenced Tregs, M2-like macrophages, Tregs/M1-like ratio, and CD11bc + CD38 + cells, indicating distinct effects from both surgery and treatment. Principal component analysis (PCA) further supported the separate effects. Our findings suggest that the splenic nerve transmits oral NaHCO3-induced immunomodulatory changes to the spleen, emphasizing NaHCO3's potential as an IR activator with therapeutic implications for a wide spectrum of systemic inflammatory conditions.
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Affiliation(s)
- Milena Rodriguez Alvarez
- School of Graduate Studies & Department of Internal Medicine, Division of Rheumatology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA.
- Department of Rheumatology, SUNY Downstate Health Sciences University, 450 Clarkson Ave, Brooklyn, NY, 11203, USA.
| | - Hussam Alkaissi
- Division of Diabetes, Endocrinology, and Metabolic Diseases, NIH/NIDDK, Bethesda, MD, USA
| | - Aja M Rieger
- Department of Medical Microbiology and Immunology, University of Alberta, Alberta, Canada
| | - Guillem R Esber
- Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Canada
| | - Manuel E Acosta
- Mathematics and Computer Sciences Department, Barry University, Miami, FL, USA
| | - Stacy I Stephenson
- Division of Comparative Medicine, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Allison V Maurice
- Division of Comparative Medicine, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | | | - Christopher A Roman
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Juan Marcos Alarcon
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
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4
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Mannon EC, Muller PR, Sun J, Bush WB, Coleman A, Ocasio H, Polichnowski AJ, Brands MW, O'Connor PM. NaHCO3 loading causes increased arterial pressure and kidney damage in rats with chronic kidney disease. Clin Sci (Lond) 2024; 138:189-203. [PMID: 38300615 DOI: 10.1042/cs20231709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/26/2024] [Accepted: 02/01/2024] [Indexed: 02/02/2024]
Abstract
Sodium bicarbonate (NaHCO3) is commonly utilized as a therapeutic to treat metabolic acidosis in people with chronic kidney disease (CKD). While increased dietary sodium chloride (NaCl) is known to promote volume retention and increase blood pressure, the effects of NaHCO3 loading on blood pressure and volume retention in CKD remain unclear. In the present study, we compared the effects of NaCl and NaHCO3 loading on volume retention, blood pressure, and kidney injury in both 2/3 and 5/6 nephrectomy remnant kidney rats, a well-established rodent model of CKD. We tested the hypothesis that NaCl loading promotes greater volume retention and increases in blood pressure than equimolar NaHCO3. Blood pressure was measured 24 h daily using radio telemetry. NaCl and NaHCO3 were administered in drinking water ad libitum or infused via indwelling catheters. Rats were housed in metabolic cages to determine volume retention. Our data indicate that both NaHCO3 and NaCl promote hypertension and volume retention in remnant kidney rats, with salt-sensitivity increasing with greater renal mass reduction. Importantly, while NaHCO3 intake was less pro-hypertensive than equimolar NaCl intake, NaHCO3 was not benign. NaHCO3 loading significantly elevated blood pressure and promoted volume retention in rats with CKD when compared with control rats receiving tap water. Our findings provide important insight into the effects of sodium loading with NaHCO3 in CKD and indicate that NaHCO3 loading in patients with CKD is unlikely to be benign.
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Affiliation(s)
- Elinor C Mannon
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia, U.S.A
| | - P Robinson Muller
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia, U.S.A
| | - Jingping Sun
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia, U.S.A
| | - Weston B Bush
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia, U.S.A
| | - Alex Coleman
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia, U.S.A
| | - Hiram Ocasio
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia, U.S.A
| | - Aaron J Polichnowski
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee, U.S.A
| | - Michael W Brands
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia, U.S.A
| | - Paul M O'Connor
- Department of Physiology, Medical College of Georgia at Augusta University, Augusta, Georgia, U.S.A
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5
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The mechanisms of alkali therapy in targeting renal diseases. Biochem Soc Trans 2023; 51:223-232. [PMID: 36744634 DOI: 10.1042/bst20220690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/28/2022] [Accepted: 01/19/2023] [Indexed: 02/07/2023]
Abstract
Chronic kidney disease (CKD) is characterized by progressive reduction in kidney function and treatments aiming at stabilizing or slowing its progression may avoid or delay the necessity of kidney replacement therapy and the increased mortality associated with reduced kidney function. Metabolic acidosis, and less severe stages of the acid stress continuum, are common consequences of CKD and some interventional studies support that its correction slows the progression to end-stage kidney disease. This correction can be achieved with mineral alkali in the form of bicarbonate or citrate salts, ingestion of diets with fewer acid-producing food components or more base-producing food components, or a pharmacological approach. In this mini-review article, we summarize the potential mechanisms involved in the beneficial effects of alkali therapy. We also discuss the perspectives in the field and challenges that must be overcome to advance our understanding of such mechanisms.
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Chivers JM, Whiles SA, Miles CB, Biederman BE, Ellison MF, Lovingood CW, Wright MH, Hoover DB, Raafey MA, Youngberg GA, Venkatachalam MA, Zheleznova NN, Yang C, Liu P, Kriegel AJ, Cowley AW, O'Connor PM, Picken MM, Polichnowski AJ. Brown-Norway chromosome 1 mitigates the upregulation of proinflammatory pathways in mTAL cells and subsequent age-related CKD in Dahl SS/JrHsdMcwi rats. Am J Physiol Renal Physiol 2023; 324:F193-F210. [PMID: 36475869 PMCID: PMC9886360 DOI: 10.1152/ajprenal.00145.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 11/23/2022] [Accepted: 11/25/2022] [Indexed: 12/13/2022] Open
Abstract
Chronic kidney disease (CKD) has a strong genetic component; however, the underlying pathways are not well understood. Dahl salt-sensitive (SS)/Jr rats spontaneously develop CKD with age and are used to investigate the genetic determinants of CKD. However, there are currently several genetically diverse Dahl SS rats maintained at various institutions and the extent to which some exhibit age-related CKD is unclear. We assessed glomerulosclerosis (GS) and tubulointerstitial fibrosis (TIF) in 3- and 6-mo-old male and female SS/JrHsdMcwi, BN/NHsd/Mcwi [Brown-Norway (BN)], and consomic SS-Chr 1BN/Mcwi (SS.BN1) rats, in which chromosome 1 from the BN rat was introgressed into the genome of the SS/JrHsdMcwi rat. Rats were fed a 0.4% NaCl diet. GS (31 ± 3% vs. 7 ± 1%) and TIF (2.3 ± 0.2 vs. 0.5 ± 0.1) were significantly greater in 6-mo-old compared with 3-mo-old SS/JrHsdMcwi rats, and CKD was exacerbated in males. GS was minimal in 6- and 3-mo-old BN (3.9 ± 0.6% vs. 1.2 ± 0.4%) and SS.BN1 (2.4 ± 0.5% vs. 1.0 ± 0.3%) rats, and neither exhibited TIF. In SS/JrHsdMcwi and SS.BN1 rats, mean arterial blood pressure was significantly greater in 6-mo-old compared with 3-mo-old SS/JrHsdMcwi (162 ± 4 vs. 131 ± 2 mmHg) but not SS.BN1 (115 ± 2 vs. 116 ± 1 mmHg) rats. In 6-mo-old SS/JrHsdMcwi rats, blood pressure was significantly greater in females. RNA-sequencing analysis revealed that inflammatory pathways were upregulated in isolated medullary thick ascending tubules in 7-wk-old SS/JrHsdMcwi rats, before the development of tubule pathology, compared with SS.BN1 rats. In summary, SS/JrHsdMcwi rats exhibit robust age-related progression of medullary thick ascending limb abnormalities, CKD, and hypertension, and gene(s) on chromosome 1 have a major pathogenic role in such changes.NEW & NOTEWORTHY This study shows that the robust age-related progression of kidney disease in Dahl SS/JrHsdMcw rats maintained on a normal-salt diet is abolished in consomic SS.BN1 rats. Evidence that medullary thick ascending limb segments of SS/JrHsdMcw rats are structurally abnormal and enriched in proinflammatory pathways before the development of protein casts provides new insights into the pathogenesis of kidney disease in this model.
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Affiliation(s)
- Jacqueline M Chivers
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee
| | - Shannon A Whiles
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee
| | - Conor B Miles
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee
| | - Brianna E Biederman
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee
| | - Megan F Ellison
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee
| | - Connor W Lovingood
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee
| | - Marie H Wright
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee
| | - Donald B Hoover
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee
- Center of Excellence in Inflammation, Infectious Disease and Immunity, East Tennessee State University, Johnson City, Tennessee
| | - Muhammad A Raafey
- Department of Pathology, Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee
| | - George A Youngberg
- Department of Pathology, Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee
| | | | | | - Chun Yang
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Pengyuan Liu
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Alison J Kriegel
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Allen W Cowley
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Paul M O'Connor
- Department of Physiology, Augusta University, Augusta, Georgia
| | - Maria M Picken
- Department of Pathology, Loyola University Medical Center, Maywood, Illinois
| | - Aaron J Polichnowski
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee
- Center of Excellence in Inflammation, Infectious Disease and Immunity, East Tennessee State University, Johnson City, Tennessee
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Alvarez MR, Alarcon JM, Roman CA, Lazaro D, Bobrowski-Khoury N, Baena-Caldas GP, Esber GR. Can a basic solution activate the inflammatory reflex? A review of potential mechanisms, opportunities, and challenges. Pharmacol Res 2023; 187:106525. [PMID: 36441036 DOI: 10.1016/j.phrs.2022.106525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/09/2022] [Accepted: 10/25/2022] [Indexed: 11/24/2022]
Abstract
Stimulation of the inflammatory reflex (IR) is a promising strategy to treat systemic inflammatory disorders. However, this strategy is hindered by the cost and side effects of traditional IR activators. Recently, oral intake of sodium bicarbonate (NaHCO3) has been suggested to activate the IR, providing a safe and inexpensive alternative. Critically, the mechanisms whereby NaHCO3 might achieve this effect and more broadly the pathways underlying the IR remain poorly understood. Here, we argue that the recognition of NaHCO3 as a potential IR activator presents exciting clinical and research opportunities. To aid this quest, we provide an integrative review of our current knowledge of the neural and cellular pathways mediating the IR and discuss the status of physiological models of IR activation. From this vantage point, we derive testable hypotheses on potential mechanisms whereby NaHCO3 might stimulate the IR and compare NaHCO3 with classic IR activators. Elucidation of these mechanisms will help determine the therapeutic value of NaHCO3 as an IR activator and provide new insights into the IR circuitry.
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Affiliation(s)
- Milena Rodriguez Alvarez
- Department of Internal Medicine, Division of Rheumatology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA.
| | - Juan Marcos Alarcon
- Department of Pathology, The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, USA
| | - Christopher A Roman
- Department of Cell Biology, State University of New York (SUNY) Downstate Health Sciences University, Brooklyn, NY 11203, USA
| | - Deana Lazaro
- Division of Rheumatology, Department of Internal Medicine, Veterans Affairs New York Harbor Healthcare System, Brooklyn, NY, USA
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New mechanisms for the kidney-protective effect of alkali in chronic kidney disease. Clin Sci (Lond) 2022; 136:1433-1437. [DOI: 10.1042/cs20220395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 08/25/2022] [Accepted: 08/30/2022] [Indexed: 11/17/2022]
Abstract
Abstract
Worldwide, more than one in ten adults are estimated to have chronic kidney disease (CKD). As CKD progresses, both the cost of treatment and associated risk of morbidity and mortality increase exponentially. As such, there is a great need for therapies that effectively slow CKD progression. Evidence from several small clinical trials indicates that alkali therapy may slow the rate of CKD progression. The biological mechanisms underlying this protective effect, however, remain unknown. In their recently published manuscript, Pastor Arroyo et al. (Clin Sci (Lond) (2022) 136(8): https://doi.org/10.1042/CS20220095) demonstrate that the alkali sodium bicarbonate protects against loss of renal function in a crystal nephropathy model in mice. Using unbiased approaches in both mice and human tissue, the authors go on to identify two novel mechanisms that may underly this protection. The first pathway is through promoting pathways of cell metabolism, which they speculate helps the remaining functional nephrons adapt to the greater metabolic needs required to maintain kidney filtration. The second pathway is by restoration of α-Klotho levels, which may limit the expression of adhesion molecules in the injured kidney. This, the authors speculate, may prevent inflammation from driving the functional decline of the kidney. Identifying these novel pathways represents an important step forward harnessing the potential benefits of alkali therapy in CKD.
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9
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Mannon EC, Sartain CL, Wilkes TC, Sun J, Polichnowski AJ, O'Connor PM. RENAL MASS REDUCTION INCREASES THE RESPONSE TO EXOGENOUS INSULIN INDEPENDENT OF ACID-BASE STATUS OR PLASMA INSULIN LEVELS IN RATS. Am J Physiol Renal Physiol 2021; 321:F494-F504. [PMID: 34396787 DOI: 10.1152/ajprenal.00679.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Impairments in insulin sensitivity can occur in patients with chronic kidney disease (CKD). Correction of metabolic acidosis has been associated with improved insulin sensitivity in CKD, suggesting metabolic acidosis may directly promote insulin resistance. Despite this, the effect of acid or alkali loading on insulin sensitivity in a rodent model of CKD (remnant kidney) has not been directly investigated. Such studies could better define the relationship between blood pH and insulin sensitivity. We hypothesized that in remnant kidney rats, acid or alkali loading would promote loss of pH homeostasis and consequently decrease insulin sensitivity. To test this hypothesis, we determined the impact of alkali (2 weeks) or acid (5-7 days) loading on plasma electrolytes, acid-base balance, and insulin sensitivity in either sham control, 2/3 or 5/6 nephrectomy rats. Rats with 5/6 nephrectomy had the greatest response to insulin followed by animals with 2/3 nephrectomy and sham control rats. We found that treatment with a 0.1M sodium bicarbonate solution in drinking water had no effect on insulin sensitivity. Acid loading with 0.1M ammonium chloride resulted in significant reductions in pH and plasma bicarbonate. However, acidosis did not significantly impair insulin sensitivity. Similar effects were observed in Zucker obese rats with 5/6 nephrectomy. The effect of renal mass reduction on insulin sensitivity could not be explained by reduced insulin clearance or increased plasma insulin levels. We found that renal mass reduction alone increases sensitivity to exogenous insulin in rats, and that this is not acutely reversed by development of acidosis.
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Affiliation(s)
- Elinor C Mannon
- Department of Physiology, Augusta University, Augusta, Georgia, United States
| | - Christina L Sartain
- Department of Physiology, Augusta University, Augusta, Georgia, United States
| | - Trevin C Wilkes
- Medical College of Georgia at Augusta University, Augusta, Georgia, United States
| | - Jingping Sun
- Department of Physiology, Augusta University, Augusta, Georgia, United States
| | - Aaron J Polichnowski
- Department of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee, United States
| | - Paul M O'Connor
- Department of Physiology, Augusta University, Augusta, Georgia, United States
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Mannon EC, O'Connor PM. Alkali supplementation as a therapeutic in chronic kidney disease: what mediates protection? Am J Physiol Renal Physiol 2020; 319:F1090-F1104. [PMID: 33166183 DOI: 10.1152/ajprenal.00343.2020] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Sodium bicarbonate (NaHCO3) has been recognized as a possible therapy to target chronic kidney disease (CKD) progression. Several small clinical trials have demonstrated that supplementation with NaHCO3 or other alkalizing agents slows renal functional decline in patients with CKD. While the benefits of NaHCO3 treatment have been thought to result from restoring pH homeostasis, a number of studies have now indicated that NaHCO3 or other alkalis may provide benefit regardless of the presence of metabolic acidosis. These data have raised questions as to how NaHCO3 protects the kidneys. To date, the physiological mechanism(s) that mediates the reported protective effect of NaHCO3 in CKD remain unclear. In this review, we first examine the evidence from clinical trials in support of a beneficial effect of NaHCO3 and other alkali in slowing kidney disease progression and their relationship to acid-base status. Then, we discuss the physiological pathways that have been proposed to underlie these renoprotective effects and highlight strengths and weaknesses in the data supporting each pathway. Finally, we discuss how answering key questions regarding the physiological mechanism(s) mediating the beneficial actions of NaHCO3 therapy in CKD is likely to be important in the design of future clinical trials. We conclude that basic research in animal models is likely to be critical in identifying the physiological mechanisms underlying the benefits of NaHCO3 treatment in CKD. Gaining an understanding of these pathways may lead to the improved implementation of NaHCO3 as a therapy in CKD and perhaps other disease states.
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Affiliation(s)
- Elinor C Mannon
- Department of Physiology, Augusta University, Augusta, Georgia
| | - Paul M O'Connor
- Department of Physiology, Augusta University, Augusta, Georgia
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11
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Li W, Ward R, Dong G, Ergul A, O'Connor P. Neurovascular protection in voltage-gated proton channel Hv1 knock-out rats after ischemic stroke: interaction with Na + /H + exchanger-1 antagonism. Physiol Rep 2020; 7:e14142. [PMID: 31250553 PMCID: PMC6597793 DOI: 10.14814/phy2.14142] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 05/21/2019] [Indexed: 12/14/2022] Open
Abstract
Experimental studies have demonstrated protective effects of NHE‐1 inhibition on cardiac function; however, clinical trials utilizing NHE‐1 antagonists found an increase in overall mortality attributed to thromboembolic strokes. NADPH oxidase‐derived reactive oxygen species (ROS) from microglial cells have been shown to contribute to injury following stroke. We have recently demonstrated that NHE‐1 inhibition enhances ROS in macrophages in a Hv1‐dependent manner. As Hv1 protein is highly expressed in microglia, we hypothesized that “NHE‐1 inhibition may augment neurovascular injury by activating Hv1,” providing a potential mechanism for the deleterious effects of NHE‐1. The goal of this study was to determine whether neurovascular injury and functional outcomes after experimental stroke differed in wild‐type and Hv1 mutant Dahl salt‐sensitive rats treated with an NHE‐1 inhibitor. Stroke was induced using both transient and permanent of middle cerebral artery occlusion (MCAO). Animals received vehicle or NHE‐1 inhibitor KR32568 (2 mg/kg, iv) either 30 min after the start of MCAO or were pretreated (2 mg/kg, iv, day) for 3 days and then subjected to MCAO. Our data indicate that Hv1 deletion confers both neuronal and vascular protection after ischemia. In contrast to our hypothesis, inhibition of NHE‐1 provided further protection from ischemic stroke, and the beneficial effects of both pre‐ and post‐treatment with KR32568 were similar in wild‐type and Hv1−/− rats. These data indicate that Hv1 activation is unlikely to be responsible for the increased incidence of cerebrovascular events observed in the heart disease patients after NHE‐1 inhibition treatment.
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Affiliation(s)
- Weiguo Li
- Department of Pathology & Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina.,Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina
| | - Rebecca Ward
- Departments of Neuroscience & Regenerative Medicine, Augusta University, Augusta, Georgia
| | - Guangkuo Dong
- Department of Physiology, Augusta University, Augusta, Georgia
| | - Adviye Ergul
- Department of Pathology & Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina.,Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina
| | - Paul O'Connor
- Department of Physiology, Augusta University, Augusta, Georgia
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12
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Patel B, Zheleznova NN, Ray SC, Sun J, Cowley AW, O'Connor PM. Voltage gated proton channels modulate mitochondrial reactive oxygen species production by complex I in renal medullary thick ascending limb. Redox Biol 2019; 27:101191. [PMID: 31060879 PMCID: PMC6859587 DOI: 10.1016/j.redox.2019.101191] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 04/02/2019] [Accepted: 04/05/2019] [Indexed: 11/24/2022] Open
Abstract
Hv1 is a voltage-gated proton channel highly expressed in immune cells where, it acts to maintain NAD(P)H oxidase activity during the respiratory burst. We have recently reported that Hv1 is expressed in cells of the medullary thick ascending limb (mTAL) of the kidney and is critical to augment reactive oxygen species (ROS) production by this segment. While Hv1 is associated with NOX2 mediated ROS production in immune cells, the source of the Hv1 dependent ROS in mTAL remains unknown. In the current study, the rate of ROS formation was quantified in freshly isolated mTAL using dihydroethidium and ethidium fluorescence. Hv1 dependent ROS production was stimulated by increasing bath osmolality and ammonium chloride (NH4Cl) loading. Loss of either p67phox or NOX4 did not abolish the formation of ROS in mTAL. Hv1 was localized to mitochondria within mTAL, and the mitochondrial superoxide scavenger mitoTEMPOL reduced ROS formation. Rotenone significantly increased ROS formation and decreased mitochondrial membrane potential in mTAL from wild-type rats, while treatment with this inhibitor decreased ROS formation and increased mitochondrial membrane potential in mTAL from Hv1−/− mutant rats. These data indicate that NADPH oxidase is not the primary source of Hv1 dependent ROS production in mTAL. Rather Hv1 localizes to the mitochondria in mTAL and modulates the formation of ROS by complex I. These data provide a potential explanation for the effects of Hv1 on ROS production in cells independent of its contribution to maintenance of cell membrane potential and intracellular pH.
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Affiliation(s)
- Bansari Patel
- Department of Physiology, Medical College of Georgia, Augusta, Georgia, USA
| | | | - Sarah C Ray
- Department of Physiology, Medical College of Georgia, Augusta, Georgia, USA
| | - Jingping Sun
- Department of Physiology, Medical College of Georgia, Augusta, Georgia, USA
| | - Allen W Cowley
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Paul M O'Connor
- Department of Physiology, Medical College of Georgia, Augusta, Georgia, USA.
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13
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Mannon EC, Sun J, Wilson K, Brands M, Martinez-Quinones P, Baban B, O'Connor PM. A basic solution to activate the cholinergic anti-inflammatory pathway via the mesothelium? Pharmacol Res 2019; 141:236-248. [PMID: 30616018 DOI: 10.1016/j.phrs.2019.01.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 12/20/2018] [Accepted: 01/03/2019] [Indexed: 12/24/2022]
Abstract
Much research now indicates that vagal nerve stimulation results in a systemic reduction in inflammatory cytokine production and an increase in anti-inflammatory cell populations that originates from the spleen. Termed the 'cholinergic anti-inflammatory pathway', therapeutic activation of this innate physiological response holds enormous promise for the treatment of inflammatory disease. Much controversy remains however, regarding the underlying physiological pathways mediating this response. This controversy is anchored in the fact that the vagal nerve itself does not innervate the spleen. Recent research from our own laboratory indicating that oral intake of sodium bicarbonate stimulates splenic anti-inflammatory pathways, and that this effect may require transmission of signals to the spleen through the mesothelium, provide new insight into the physiological pathways mediating the cholinergic anti-inflammatory pathway. In this review, we examine proposed models of the cholinergic anti-inflammatory pathway and attempt to frame our recent results in relation to these hypotheses. Following this discussion, we then provide an alternative model of the cholinergic anti-inflammatory pathway which is consistent both with our recent findings and the published literature. We then discuss experimental approaches that may be useful to delineate these hypotheses. We believe the outcome of these experiments will be critical in identifying the most appropriate methods to harness the therapeutic potential of the cholinergic anti-inflammatory pathway for the treatment of disease and may also shed light on the etiology of other pathologies, such as idiopathic fibrosis.
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Affiliation(s)
- Elinor C Mannon
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Jingping Sun
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Katie Wilson
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Michael Brands
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Patricia Martinez-Quinones
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, United States; Department of Surgery, Augusta University Medical Center, Augusta University, Augusta, GA, United States
| | - Babak Baban
- Department of Oral Biology, Augusta University, Augusta, GA, United States
| | - Paul M O'Connor
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, United States
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14
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Bushinsky DA. Tolerance to Sodium in Patients With CKD-Induced Metabolic Acidosis: Does the Accompanying Anion Matter? Am J Kidney Dis 2018; 73:858-865. [PMID: 30518477 DOI: 10.1053/j.ajkd.2018.09.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 09/07/2018] [Indexed: 11/11/2022]
Abstract
Patients with chronic kidney disease (CKD) continue to produce endogenous acids but have a reduction in net acid excretion, resulting in a primary decrease in serum bicarbonate concentration, which is termed chronic metabolic acidosis. Recent prospective studies, along with retrospective cohort analyses, demonstrate a higher risk for CKD progression with untreated metabolic acidosis. To normalize serum bicarbonate levels, acidemic patients are often treated with sodium bicarbonate (NaHCO3) or sodium citrate, which have been shown to slow the progression of CKD. However, studies using this approach have routinely excluded patients with common sodium-sensitive comorbid conditions, such as poorly controlled hypertension, congestive heart failure, volume overload, or edema. This article examines the effect of the anion that accompanies sodium delivered with these therapies. Do the negative effects on blood pressure (BP) and sodium retention, as measured by an increase in edema, weight gain, and congestive heart failure, observed with oral administration of sodium chloride (NaCl) differ when a similar amount of sodium is given with bicarbonate or citrate in this patient population? A review of the literature suggests that NaHCO3 does not increase BP or sodium retention when administered to patients with CKD during a concurrent severe NaCl dietary restriction (∼10 mEq/d). However, this degree of NaCl restriction is feasible only under strict control in clinical research environments. In contrast, when NaHCO3 is given to patients without severe dietary NaCl restriction, there is an increase in BP and sodium retention. Thus, unless patients with CKD can tolerate a diet virtually devoid of NaCl, additional sodium, regardless of the accompanying anion, appears to increase BP and sodium retention.
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Affiliation(s)
- David A Bushinsky
- University of Rochester School of Medicine and Dentistry, Rochester, NY.
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15
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Buffering chronic kidney disease with sodium bicarbonate. Clin Sci (Lond) 2018; 132:1999-2001. [PMID: 30220653 DOI: 10.1042/cs20180292] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 08/01/2018] [Accepted: 08/07/2018] [Indexed: 11/17/2022]
Abstract
The roles of the kidney are well defined, if there is a progressive loss in renal function, the kidney is no longer able to perform the listed tasks and chronic kidney disease (CKD) persists. In both clinical and experimental studies, NaHCO3 supplementation has been shown to improve glomerular filtration rate (GFR) as well as halt the progression toward end-stage renal disease (ESRD). In an article recently published in Clinical Science (vol 132 (11) 1179-1197), Ray et al. presented an intriguing and timely study, which investigates the mechanisms involved in the protection that follows oral NaHCO3 ingestion. Here we comment on their research findings.
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