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Singh P, Stephenson R, Castillo A, Majid DSA. High-salt intake reduces renal tissue levels of inflammatory cytokines in mice. Physiol Rep 2021; 8:e14621. [PMID: 33345460 PMCID: PMC7750173 DOI: 10.14814/phy2.14621] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/28/2020] [Accepted: 10/01/2020] [Indexed: 12/24/2022] Open
Abstract
High salt (HS) intake is usually considered as an aggravating factor to induce inflammatory renal injury. However, the changes in the renal levels of inflammatory cytokines during HS intake is not yet clearly defined. We hypothesize that HS increases renal levels of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) but decreases interleukin-10 (IL-10; anti-inflammatory cytokine) and these responses exacerbate in NO deficient conditions. Both wild-type (WT) and endothelial NO synthase knockout (eNOSKO) mice (~8 weeks old, n = 6 in each group) were given normal-salt (NS; 0.3% NaCl) and HS (4% NaCl) containing diets for 2 weeks. Systolic blood pressure (SBP) was determined by tail-cuff plethysmography and urine collections were made using metabolic cages. Basal SBP was higher in eNOSKO than WT mice (131 ± 7 vs 117 ± 3 mmHg; p < .05). HS intake for 2 weeks increased SBP in eNOSKO (161 ± 5 mmHg) but not in WT mice. In NS groups, the cytokine levels in renal tissues (measured using ELISA kits and expressed in pg/mg protein) were significantly higher in eNOSKO than WT mice (TNF-α, 624 ± 67 vs. 325 ± 73; IL-6, 619 ± 106 vs. 166 ± 61; IL-10, 6,087 ± 567 vs. 3,929 ± 378). Interestingly, these cytokine levels in HS groups were significantly less both in WT (TNF-α, 114 ± 17; IL-6, 81 ± 14; IL-10, 865 ± 130) and eNOSKO (TNF-α, 115 ± 18; IL-6, 56 ± 7; IL-10, 882 ± 141) mice. These findings indicate that HS induces downregulation of cytokines in the kidney. Such HS-induced reduction in cytokines, particularly TNF-α (a natriuretic agent), would facilitate more salt-retention, and thus, leading to salt-sensitive hypertension in NO deficient conditions.
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Affiliation(s)
- Purnima Singh
- Department of Physiology, Hypertension and Renal Centre of ExcellenceTulane University School of MedicineNew OrleansLAUSA
| | - Roxan Stephenson
- Department of Physiology, Hypertension and Renal Centre of ExcellenceTulane University School of MedicineNew OrleansLAUSA
| | - Alexander Castillo
- Department of Physiology, Hypertension and Renal Centre of ExcellenceTulane University School of MedicineNew OrleansLAUSA
| | - Dewan S. A. Majid
- Department of Physiology, Hypertension and Renal Centre of ExcellenceTulane University School of MedicineNew OrleansLAUSA
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Singh P, Castillo A, Islam MT, Majid DSA. Evidence for Prohypertensive, Proinflammatory Effect of Interleukin-10 During Chronic High Salt Intake in the Condition of Elevated Angiotensin II Level. Hypertension 2017; 70:839-845. [PMID: 28847894 DOI: 10.1161/hypertensionaha.117.09401] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 03/30/2017] [Accepted: 07/07/2017] [Indexed: 12/31/2022]
Abstract
IL-10 (interleukin-10) has been suggested to play a protective role in angiotensin II (AngII)-induced cardiovascular disorders. This study examined the role of endogenous IL-10 in salt-sensitive hypertension and renal injury induced by AngII. Responses to chronic AngII (400 ng/min per kilogram body weight; osmotic minipump) infusion were evaluated in IL-10 gene knockout mice fed with either normal salt diet (0.3% NaCl) or high salt (HS; 4% NaCl) diet, and these responses were compared with those in wild-type mice. Normal salt diets or HS diets were given alone for the first 2 weeks and then with AngII treatment for an additional 2 weeks (n=6 in each group). Arterial pressure was continuously monitored by implanted radio-telemetry, and a 24-hour urine collection was performed by metabolic cages on the last day of the experimental period. Basal mean arterial pressure was lower in IL-10 gene knockout mice than in wild-type (98±3 versus 113±3 mm Hg) mice. Mean arterial pressure responses to normal salt/HS alone or to the AngII+normal salt treatment were similar in both strains. However, the increase in mean arterial pressure induced by the AngII+HS treatment was significantly lower in IL-10 gene knockout mice (15±5% versus 37±3%) compared with wild-type mice. Renal tissue endothelial nitric oxide synthase expression (≈3-folds) and urinary excretion of nitric oxide metabolites, nitrate/nitrite (1.2±0.1 versus 0.2±0.02 µmol/L/24 hours) were higher in IL-10 gene knockout mice compared with wild-type mice. These results indicate that an increase in nitric oxide production helps to mitigate salt-sensitive hypertension induced by AngII and suggest that a compensatory interaction between IL-10 and nitric oxide exists in modulating AngII-induced responses during HS intake.
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Affiliation(s)
- Purnima Singh
- From the Department of Physiology, Tulane University School of Medicine, New Orleans, LA
| | - Alexander Castillo
- From the Department of Physiology, Tulane University School of Medicine, New Orleans, LA
| | - M Toriqul Islam
- From the Department of Physiology, Tulane University School of Medicine, New Orleans, LA
| | - Dewan S A Majid
- From the Department of Physiology, Tulane University School of Medicine, New Orleans, LA.
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Suehiro T, Tsuruya K, Ikeda H, Toyonaga J, Yamada S, Noguchi H, Tokumoto M, Kitazono T. Systemic Aldosterone, But Not Angiotensin II, Plays a Pivotal Role in the Pathogenesis of Renal Injury in Chronic Nitric Oxide-Deficient Male Rats. Endocrinology 2015; 156:2657-66. [PMID: 25872005 DOI: 10.1210/en.2014-1369] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Chronic inhibition of nitric oxide synthase by N(ω)-nitro-L-arginine methyl ester (L-NAME) causes progressive renal injury and systemic hypertension. Angiotensin II (Ang II) has been conventionally regarded as one of the primary causes of renal injury. We reported previously that such renal injury was almost completely suppressed by both an Ang II type I receptor blocker and an aldosterone antagonist. The aldosterone antagonist also inhibited the systemic Ang II elevation. Therefore, it remains to be elucidated whether Ang II or aldosterone directly affects the development of such renal injury. In the present study, we investigated the role of aldosterone in the pathogenesis of renal injury induced by L-NAME-mediated chronic nitric oxide synthase inhibition in male Wistar rats (aged 10 wk). Serial analyses demonstrated that the renal injury and inflammation in L-NAME-treated rats was associated with elevation of both Ang II and aldosterone. To investigate the direct effect of aldosterone on the renal injury, we conducted adrenalectomy (ADX) and aldosterone supplementation in L-NAME-treated rats. In ADX rats, aldosterone was undetectable, and renal injury and inflammation were almost completely prevented by ADX, although systemic and local Ang II and blood pressure were still elevated. Aldosterone supplementation reversed the beneficial effect of ADX. The present study indicates that aldosterone rather than Ang II plays a central and direct role in the pathogenesis of renal injury by L-NAME through inflammation, independent of its systemic hemodynamic effects.
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Affiliation(s)
- Takaichi Suehiro
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
| | - Kazuhiko Tsuruya
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
| | - Hirofumi Ikeda
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
| | - Jiro Toyonaga
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
| | - Shunsuke Yamada
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
| | - Hideko Noguchi
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
| | - Masanori Tokumoto
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
| | - Takanari Kitazono
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
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Majid DSA, Prieto MC, Navar LG. Salt-Sensitive Hypertension: Perspectives on Intrarenal Mechanisms. Curr Hypertens Rev 2015; 11:38-48. [PMID: 26028244 DOI: 10.2174/1573402111666150530203858] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 04/22/2015] [Accepted: 04/24/2015] [Indexed: 12/12/2022]
Abstract
Salt sensitive hypertension is characterized by increases in blood pressure in response to increases in dietary salt intake and is associated with an enhanced risk of cardiovascular and renal morbidity. Although researchers have sought for decades to understand how salt sensitivity develops in humans, the mechanisms responsible for the increases in blood pressure in response to high salt intake are complex and only partially understood. Until now, scientists have been unable to explain why some individuals are salt sensitive and others are salt resistant. Although a central role for the kidneys in the development of salt sensitivity and hypertension has been generally accepted, it is also recognized that hypertension is of multifactorial origin and a variety of factors can induce, or prevent, blood pressure responsiveness to the manipulation of salt intake. Excess salt intake in susceptible persons may also induce inappropriate central and sympathetic nervous system responses and increase the production of intrarenal angiotensin II, catecholamines and other factors such as oxidative stress and inflammatory cytokines. One key factor is the concomitant inappropriate or paradoxical activation of the intrarenal renin-angiotensin system, by high salt intake. This is reflected by the increases in urinary angiotensinogen during high salt intake in salt sensitive models. A complex interaction between neuroendocrine factors and the kidney may underlie the propensity for some individuals to retain salt and develop salt-dependent hypertension. In this review, we focus mainly on the renal contributions that provide the mechanistic links between chronic salt intake and the development of hypertension.
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Affiliation(s)
- Dewan S A Majid
- Department of Physiology, SL39, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
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Matafora V, Zagato L, Ferrandi M, Molinari I, Zerbini G, Casamassima N, Lanzani C, Delli Carpini S, Trepiccione F, Manunta P, Bachi A, Capasso G. Quantitative proteomics reveals novel therapeutic and diagnostic markers in hypertension. BBA CLINICAL 2014; 2:79-87. [PMID: 26672470 PMCID: PMC4633972 DOI: 10.1016/j.bbacli.2014.10.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 10/01/2014] [Accepted: 10/06/2014] [Indexed: 01/13/2023]
Abstract
Hypertension is a prevalent disorder in the world representing one of the major risk factors for heart attack and stroke. These risks are increased in salt sensitive individuals. Hypertension and salt sensitivity are complex phenotypes whose pathophysiology remains poorly understood and, remarkably, salt sensitivity is still laborious to diagnose. Here we present a urinary proteomic study specifically designed to identify urinary proteins relevant for the pathogenesis of hypertension and salt sensitivity. Despite previous studies that underlined the association of UMOD gene variants with hypertension, this work provides novel evidence showing different uromodulin protein level in the urine of hypertensive patients compared to healthy individuals. Notably, we also show that patients with higher level of uromodulin are homozygous for UMOD risk variant and display a decreased level of salt excretion, highlighting the essential role of UMOD in the regulation of salt reabsorption in hypertension. Additionally, we found that urinary nephrin 1, a marker of glomerular slit diaphragm, may predict a salt sensitive phenotype and positively correlate with increased albuminuria associated with this type of hypertension. We identified urinary proteins differently excreted in hypertensive patients. Nephrin 1 might predict salt sensitive phenotype and glomerular complications. Uromodulin impacts salt homeostasis in hypertension. We provide new insights into the pathogenesis of hypertension and salt sensitivity.
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Key Words
- BMI, body mass index
- BP, blood pressure
- DBP, diastolic BP
- GO, Gene Ontology
- Glomerular injury
- LC–MS/MS, liquid chromatography coupled to tandem mass spectrometry
- MBP, mean BP.
- MQ, MaxQuant
- Nephrinuria
- Quantitative proteomics
- SBP, systolic BP
- SR, salt resistant
- SS, salt sensitive
- Salt homeostasis
- Salt sensitive hypertension
- Urinary biomarker
- Uromodulin
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Affiliation(s)
- Vittoria Matafora
- IFOM-FIRC Institute of Molecular Oncology, Milan, Italy ; Chair of Nephrology, Department of Cardio-Vascular Medicine, Second University of Naples, Naples, Italy
| | - Laura Zagato
- Genomics of Renal Diseases and Hypertension Unit, Division of Genetics & Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Mara Ferrandi
- Genomics of Renal Diseases and Hypertension Unit, Division of Genetics & Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Isabella Molinari
- Genomics of Renal Diseases and Hypertension Unit, Division of Genetics & Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Gianpaolo Zerbini
- Division of Metabolic and Cardiovascular Sciences, San Raffaele Scientific Institute, Milan, Italy
| | - Nunzia Casamassima
- Genomics of Renal Diseases and Hypertension Unit, Division of Genetics & Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Chiara Lanzani
- Genomics of Renal Diseases and Hypertension Unit, Division of Genetics & Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Simona Delli Carpini
- Genomics of Renal Diseases and Hypertension Unit, Division of Genetics & Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Francesco Trepiccione
- Chair of Nephrology, Department of Cardio-Vascular Medicine, Second University of Naples, Naples, Italy
| | - Paolo Manunta
- Genomics of Renal Diseases and Hypertension Unit, Division of Genetics & Cell Biology, San Raffaele Scientific Institute, Milan, Italy ; Chair of Nephrology, University Vita-Salute San Raffaele, Milan, Italy
| | - Angela Bachi
- IFOM-FIRC Institute of Molecular Oncology, Milan, Italy
| | - Giovambattista Capasso
- Chair of Nephrology, Department of Cardio-Vascular Medicine, Second University of Naples, Naples, Italy
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Katayama T, Sueta D, Kataoka K, Hasegawa Y, Koibuchi N, Toyama K, Uekawa K, Mingjie M, Nakagawa T, Maeda M, Ogawa H, Kim-Mitsuyama S. Long-term renal denervation normalizes disrupted blood pressure circadian rhythm and ameliorates cardiovascular injury in a rat model of metabolic syndrome. J Am Heart Assoc 2013; 2:e000197. [PMID: 23974905 PMCID: PMC3828797 DOI: 10.1161/jaha.113.000197] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Background Although renal denervation significantly reduces blood pressure in patients with resistant hypertension, the role of the renal nerve in hypertension with metabolic syndrome is unknown. We investigated the impact of long‐term renal denervation on SHR/NDmcr‐cp(+/+) (SHRcp) rats, a useful rat model of metabolic syndrome, to determine the role of the renal nerve in hypertension with metabolic syndrome. Methods and Results SHRcp rats were divided into (1) a renal denervation (RD) group and (2) a sham operation group (control) to examine the effects of long‐term RD on blood pressure circadian rhythm, renal sodium retention‐related molecules, the renin‐angiotensin‐aldosterone system, metabolic disorders, and organ injury. RD in SHRcp rats not only significantly reduced blood pressure but also normalized blood pressure circadian rhythm from the nondipper to the dipper type, and this improvement was associated with an increase in urinary sodium excretion and the suppression of renal Na+‐Cl− cotransporter upregulation. RD significantly reduced plasma renin activity. RD significantly prevented cardiovascular remodeling and impairment of vascular endothelial function and attenuated cardiovascular oxidative stress. However, RD failed to ameliorate obesity, metabolic disorders, and renal injury and failed to reduce systemic sympathetic activity in SHRcp rats. Conclusions By including the upregulation of the Na+‐Cl− cotransporter, the renal sympathetic nerve is involved in the disruption of blood pressure circadian rhythm as well as hypertension in metabolic syndrome. Thus, RD seems to be a useful therapeutic strategy for hypertension with metabolic syndrome.
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Affiliation(s)
- Tetsuji Katayama
- Department of Pharmacology and Molecular Therapeutics, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan
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The renal angiotensin system does not reveal its secrets with a cross-sectional analysis of urinary angiotensinogen levels. J Hypertens 2013; 31:840-1. [DOI: 10.1097/hjh.0b013e32835eb5a9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Weir MR, Townsend RR, Fink JC, Teal V, Sozio SM, Anderson CA, Appel LJ, Turban S, Chen J, He J, Litbarg N, Ojo A, Rahman M, Rosen L, Steigerwalt S, Strauss L, Joffe MM. Urinary sodium is a potent correlate of proteinuria: lessons from the chronic renal insufficiency cohort study. Am J Nephrol 2012; 36:397-404. [PMID: 23076013 DOI: 10.1159/000342966] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 08/26/2012] [Indexed: 11/19/2022]
Abstract
BACKGROUND While higher blood pressure is known to increase proteinuria, whether increased dietary sodium as estimated from 24-hour urinary excretion correlates with increased proteinuria in patients with chronic kidney disease (CKD) is not well studied. METHODS We measured 24-hour urinary sodium, potassium and protein excretion in 3,680 participants in the Chronic Renal Insufficiency Cohort study, to determine the relationship between urinary sodium and potassium and urinary protein excretion in patients with CKD. We stratified our data based on the presence or absence of diabetes given the absence of any data on this relationship and evidence that diabetics had greater urinary protein excretion at nearly every level of urinary sodium excretion. Multiple linear regressions were used with a stepwise inclusion of covariates such as systolic blood pressure, demographics, hemoglobin A1c and type of antihypertensive medications to evaluate the relationship between urinary electrolyte excretion and proteinuria. RESULTS Our data demonstrated that urinary sodium (+1 SD above the mean), as a univariate variable, explained 12% of the variation in proteinuria (β = 0.29, p < 0.0001), with rising urinary sodium excretion associated with increasing proteinuria. The significance of that relationship was only partially attenuated with adjustment for demographic and clinical factors and the addition of 24-hour urinary potassium to the model (β = 0.13, R(2) = 0.35, p < 0.0001). CONCLUSIONS An understanding of the relationship between these clinical factors and dietary sodium may allow a more tailored approach for dietary salt restriction in patients with CKD.
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Affiliation(s)
- Matthew R Weir
- University of Maryland School of Medicine, Baltimore, MD, USA.
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Mitsuyama S. [Role of the renin-angiotensin system in the brain and cardiorenal system]. Nihon Yakurigaku Zasshi 2012; 140:121-6. [PMID: 22975826 DOI: 10.1254/fpj.140.121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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10
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Kagami S. Involvement of glomerular renin-angiotensin system (RAS) activation in the development and progression of glomerular injury. Clin Exp Nephrol 2012; 16:214-20. [PMID: 22134870 PMCID: PMC3328682 DOI: 10.1007/s10157-011-0568-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 11/11/2011] [Indexed: 12/20/2022]
Abstract
Recently, there has been a paradigm shift away from an emphasis on the role of the endocrine (circulating) renin-angiotensin system (RAS) in the regulation of the sodium and extracellular fluid balance, blood pressure, and the pathophysiology of hypertensive organ damage toward a focus on the role of tissue RAS found in many organs, including kidney. A tissue RAS implies that RAS components necessary for the production of angiotensin II (Ang II) reside within the tissue and its production is regulated within the tissue, independent of the circulating RAS. Locally produced Ang II plays a role in many physiological and pathophysiological processes such as hypertension, inflammation, oxidative stress, and tissue fibrosis. Both glomerular and tubular compartments of the kidney have the characteristics of a tissue RAS. The purpose of this article is to review the recent advances in tissue RAS research with a particular focus on the role of the glomerular RAS in the progression of renal disease.
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Affiliation(s)
- Shoji Kagami
- Department of Pediatrics, Institute of Health Biosciences, The University of Tokushima Graduate School, Kuramoto-cho-3-chome, Tokushima, 770-8503, Japan.
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Lara LS, Satou R, Bourgeois CRT, Gonzalez AA, Zsombok A, Prieto MC, Navar LG. The sodium-activated sodium channel is expressed in the rat kidney thick ascending limb and collecting duct cells and is upregulated during high salt intake. Am J Physiol Renal Physiol 2012; 303:F105-9. [PMID: 22442212 DOI: 10.1152/ajprenal.00490.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Increased dietary salt triggers oxidative stress and kidney injury in salt-sensitive hypertension; however, the mechanism for sensing increased extracellular Na(+) concentration ([Na(+)]) remains unclear. A Na(+)-activated Na(+) channel (Na sensor) described in the brain operates as a sensor of extracellular fluid [Na(+)]; nonetheless, its presence in the kidney has not been established. In the present study, we demonstrated the gene expression of the Na sensor by RT-PCR and Western blotting in the Sprague-Dawley rat kidney. Using immunofluorescence, the Na sensor was localized to the luminal side in tubular epithelial cells of collecting ducts colocalizing with aquaporin-2, a marker of principal cells, and in thick ascending limb, colocalizing with the glycoprotein Tamm-Horsfall. To determine the effect of a high-salt diet (HSD) on Na sensor gene expression, we quantified its transcript and protein levels primarily in renal medullas from control rats and rats subjected to 8% NaCl for 7 days (n = 5). HSD increased Na sensor expression levels (mRNA: from 1.2 ± 0.2 to 5.1 ± 1.3 au; protein: from 0.98 ± 0.15 to 1.74 ± 0.28 au P < 0.05) in the kidney medulla, but not in the cortex. These data indicate that rat kidney epithelial cells of the thick ascending limb and principal cells of the collecting duct possess a Na sensor that is upregulated by HSD, suggesting an important role in monitoring changes in tubular fluid [Na(+)].
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Affiliation(s)
- Lucienne S Lara
- Department of Physiology, Tulane University School of Medicine, New Orleans, LA 70112, USA.
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