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Hornstrup BG, Hoffmann-Petersen N, Lauridsen TG, Bech JN. Dietary sodium restriction reduces blood pressure in patients with treatment resistant hypertension. BMC Nephrol 2023; 24:274. [PMID: 37726656 PMCID: PMC10507975 DOI: 10.1186/s12882-023-03333-9] [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: 07/07/2023] [Accepted: 09/14/2023] [Indexed: 09/21/2023] Open
Abstract
PURPOSE Patients with treatment resistant hypertension (TRH) are at particular risk of cardiovascular disease. Life style modification, including sodium restriction, is an important part of the treatment of these patients. We aimed to analyse if self-performed dietary sodium restriction could be implemented in patients with TRH and to evaluate the effect of this intervention on blood pressure (BP). Moreover, we aimed to examine if mechanisms involving nitric oxide, body water content and BNP, renal function and handling of sodium were involved in the effect on nocturnal and 24-h BP. Also, measurement of erythrocyte sodium sensitivity was included as a possible predictor for the effect of sodium restriction on BP levels. PATIENTS AND METHODS TRH patients were included for this interventional four week study: two weeks on usual diet and two weeks on self-performed sodium restricted diet with supplementary handed out sodium-free bread. At the end of each period, 24-h BP and 24-h urine collections (sodium, potassium, ENaC) were performed, blood samples (BNP, NOx, salt blood test) were drawn, and bio impedance measurements were made. RESULTS Fifteen patients, 11 males, with a mean age of 59 years were included. After sodium restriction, urinary sodium excretion decreased from 186 (70) to 91 [51] mmol/24-h, and all but one reduced sodium excretion. Nocturnal and 24-h systolic BP were significantly reduced (- 8 and - 10 mmHg, respectively, p < 0.05). NOx increased, BNP and extracellular water content decreased, all significantly. Change in NOx correlated to the change in 24-h systolic BP. BP response after sodium restriction was not related to sodium sensitivity examined by salt blood test. CONCLUSION Self-performed dietary sodium restriction was feasible in a population of patients with TRH, and BP was significantly reduced. Increased NOx synthesis may be involved in the BP lowering effect of sodium restriction. TRIAL REGISTRATION The study was registered in Clinical trials with ID: NCT06022133.
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Affiliation(s)
- Bodil G Hornstrup
- University Clinic in Nephrology and Hypertension, Gødstrup Hospital and Aarhus University, Hospitalsparken 15, Herning, DK-7400, Denmark.
- Department of Medicine, Gødstrup Hospital, Herning, Denmark.
| | - Nikolai Hoffmann-Petersen
- University Clinic in Nephrology and Hypertension, Gødstrup Hospital and Aarhus University, Hospitalsparken 15, Herning, DK-7400, Denmark
| | - Thomas Guldager Lauridsen
- University Clinic in Nephrology and Hypertension, Gødstrup Hospital and Aarhus University, Hospitalsparken 15, Herning, DK-7400, Denmark
| | - Jesper N Bech
- University Clinic in Nephrology and Hypertension, Gødstrup Hospital and Aarhus University, Hospitalsparken 15, Herning, DK-7400, Denmark
- Department of Medicine, Gødstrup Hospital, Herning, Denmark
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McNally RJ, Morselli F, Farukh B, Chowienczyk PJ, Faconti L. A pilot study to evaluate the erythrocyte glycocalyx sensitivity to sodium as a marker for cellular salt sensitivity in hypertension. J Hum Hypertens 2023; 37:286-291. [PMID: 35414109 PMCID: PMC10063440 DOI: 10.1038/s41371-022-00683-z] [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: 06/21/2021] [Revised: 03/02/2022] [Accepted: 03/25/2022] [Indexed: 11/09/2022]
Abstract
Supressed plasma renin in patients with primary hypertension is thought to be an indirect marker of sodium-induced volume expansion which is associated with more severe hypertension and hypertension-mediated organ damage. A novel test for erythrocyte glycocalyx sensitivity to sodium (eGCSS) has been proposed as a direct measure of sodium-induced damage on erythrocyte surfaces and a marker of sensitivity of the endothelium to salt in humans. Here we explore if eGCSS relates to plasma renin and other clinical and biochemical characteristics in a cohort of patients with primary hypertension. Hypertensive subjects (n = 85, 54% male) were characterised by blood biochemistry (including plasma renin/aldosterone), urine analysis for albumin-creatinine ratio (ACR), 24-h urine sodium/potassium excretion. eGCSS was measured using a commercially available kit. Correlations between eGCSS and clinical and biochemical characteristics were explored using Spearman's correlation coefficient and characteristics compared across tertiles of eGCSS. eGCSS was inversely correlated with renin (p < 0.05), with renin 17.72 ± 18 µU/l in the highest tertile of eGCSS compared to 84.27 ± 146.5 µU/l in the lowest (p = 0.012). eGCSS was positively correlated with ACR (p < 0.01), with ACR 7.37 ± 15.29 vs. 1.25 ± 1.52 g/mol for the highest vs. lowest tertiles of eGCSS (p < 0.05). eGCSS was not correlated with other clinical characteristics or biochemical measures. These results suggests that sodium retention in hypertension characterised by a low-renin state is associated with cell membrane damage reflected by eGCSS. This may contribute to the hypertension-mediated organ damage and the excess mortality associated with sodium overload and "salt sensitivity".
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Affiliation(s)
- Ryan J McNally
- King's College London, Department of Clinical Pharmacology, British Heart Foundation Centre, London, UK
| | - Franca Morselli
- King's College London, Department of Clinical Pharmacology, British Heart Foundation Centre, London, UK
| | - Bushra Farukh
- King's College London, Department of Clinical Pharmacology, British Heart Foundation Centre, London, UK
| | - Phil J Chowienczyk
- King's College London, Department of Clinical Pharmacology, British Heart Foundation Centre, London, UK
| | - Luca Faconti
- King's College London, Department of Clinical Pharmacology, British Heart Foundation Centre, London, UK.
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Masenga SK, Pilic L, Hamooya BM, Nzala S, Heimburger DC, Mutale W, Koethe JR, Kirabo A, Munsaka SM, Elijovich F. Immediate pressor response to oral salt and its assessment in the clinic: a time series clinical trial. Clin Hypertens 2022; 28:25. [PMID: 36104796 PMCID: PMC9476589 DOI: 10.1186/s40885-022-00209-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 05/06/2022] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND High blood pressure (BP) is associated with high-salt consumption especially in sub-Saharan Africa. Although the pressor effect of salt is viewed as a chronic effect, some studies suggest that a salty meal may increase BP immediately in some individuals, and that this effect may cause endothelial dysfunction. Therefore, the aim of our research was to study the immediate pressor response to oral salt (IPROS) and its determinants, with the expectation that a simple methodology may be devised to diagnose it in the clinic or in low-resource environments. METHODS We conducted a time series trial at Livingstone Central Hospital. We present data in 127 normotensive participants who ingested 2 g of sodium chloride; their BP was monitored for 120 minutes in intervals of 10 minutes. Sociodemographic and clinical data were collected. Descriptive and inferential statistics were used for analyses of data. RESULTS Median age was 30 years (interquartile range, 22-46 years) and 52% were female patients. An increase of ≥10 mmHg in mean arterial pressure (MAP), considered a clinically significant IPROS, was present in 62% of participants. Systolic BP 30 minutes after the salt load was a significant predictor of IPROS, avoiding the need to calculate MAP in the clinic setting. CONCLUSIONS We confirm the presence of an IPROS in a high proportion (62%) of otherwise normotensive participants. The average time course for this response was 30 minutes and its duration was sustained for the 120-minutes period of study in most of the participants. Prediction of IPROS by ∆SBP (change in systolic blood pressure) at 30 minutes allows for easy assessment of possible responder status in the clinic. Our data indicate that the IPROS to oral salt-loads in the range currently consumed by the Western world and African populations in single meals may increase the 24-hour BP load, which is a risk factor for hypertension and target organ damage. The relevance of our findings indicates the need to include dietary sodium assessment in the diagnosis, prevention, and management of high BP.
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Affiliation(s)
- Sepiso K. Masenga
- grid.442660.20000 0004 0449 0406HAND Research Group, School of Medicine and Health Sciences, Mulungushi University, Akapelwa street, LUTH Premises, Livingstone, Zambia ,grid.12984.360000 0000 8914 5257Department of Biomedical Sciences, School of Health Sciences, University of Zambia, Lusaka, Zambia
| | - Leta Pilic
- grid.417907.c0000 0004 5903 394XFaculty of Sport, Health and Applied Science, St. Mary’s University, Twickenham, London, UK
| | - Benson M. Hamooya
- grid.442660.20000 0004 0449 0406HAND Research Group, School of Medicine and Health Sciences, Mulungushi University, Akapelwa street, LUTH Premises, Livingstone, Zambia ,grid.12984.360000 0000 8914 5257School of Public Health and School of Medicine, University of Zambia, Lusaka, Zambia
| | - Selestine Nzala
- grid.12984.360000 0000 8914 5257School of Public Health and School of Medicine, University of Zambia, Lusaka, Zambia
| | - Douglas C. Heimburger
- grid.12984.360000 0000 8914 5257School of Public Health and School of Medicine, University of Zambia, Lusaka, Zambia ,grid.412807.80000 0004 1936 9916Department of Medicine, Vanderbilt Institute for Global Health and Vanderbilt University Medical Center, Nashville, TN USA
| | - Wilbroad Mutale
- grid.12984.360000 0000 8914 5257School of Public Health and School of Medicine, University of Zambia, Lusaka, Zambia
| | - John R. Koethe
- grid.412807.80000 0004 1936 9916Department of Medicine, Vanderbilt Institute for Global Health and Vanderbilt University Medical Center, Nashville, TN USA
| | - Annet Kirabo
- grid.412807.80000 0004 1936 9916Department of Medicine, Vanderbilt Institute for Global Health and Vanderbilt University Medical Center, Nashville, TN USA
| | - Sody M. Munsaka
- grid.12984.360000 0000 8914 5257Department of Biomedical Sciences, School of Health Sciences, University of Zambia, Lusaka, Zambia
| | - Fernando Elijovich
- grid.412807.80000 0004 1936 9916Department of Medicine, Vanderbilt Institute for Global Health and Vanderbilt University Medical Center, Nashville, TN USA
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Masenga SK, Pilic L, Malumani M, Hamooya BM. Erythrocyte sodium buffering capacity status correlates with self-reported salt intake in a population from Livingstone, Zambia. PLoS One 2022; 17:e0264650. [PMID: 35235593 PMCID: PMC8890657 DOI: 10.1371/journal.pone.0264650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 02/14/2022] [Indexed: 01/14/2023] Open
Abstract
Background Salt impairs endothelial function and increases arterial stiffness independent of blood pressure. The mechanisms are unknown. Recent evidence suggests that there is a possible link between salt consumption and sodium buffering capacity and cardiovascular disease but there is limited evidence in the populations living in Sub-Saharan Africa. The aim of our study was to explore the relationship between erythrocyte sodium buffering capacity and sociodemographic, clinical factors, and self-reported salt consumption at Livingstone Central Hospital. Methods We conducted a cross sectional study at Livingstone Central hospital among 242 volunteers accessing routine medical checkups. Sociodemographic and dietary characteristics were obtained along with clinical measurements to evaluate their health status. Sodium buffering capacity was estimated by erythrocyte sodium sensitivity (ESS) test. We used descriptive and inferential statistics to describe and examine associations between erythrocyte sodium sensitivity and independent variables. Results The median age (interquartile range) of the study sample was 27 (22, 42) years. 54% (n = 202) and 46% (n = 169) were males and females, respectively. The majority (n = 150, 62%) had an ESS of >120%. High salt intake correlated positively with ESS or negatively with vascular sodium buffering capacity. Conclusions Self-reported high salt intake was associated with poor vascular sodium buffering capacity or high ESS in the majority of middle-aged Zambians living in Livingstone. The poor vascular sodium buffering capacity implies a damaged vascular glycocalyx which may potentially lead to a leakage of sodium into the interstitium. This alone is a risk factor for the future development of hypertension and cardiovascular disease. However, future studies need to validate vascular function status when using ESS testing by including established vascular function assessments to determine its pathophysiological and clinical implications.
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Affiliation(s)
- Sepiso K. Masenga
- HAND Research Group, School of Medicine and Health Sciences, Mulungushi University, Livingstone, Zambia
- * E-mail: ,
| | - Leta Pilic
- Faculty of Sport, Allied Health and Performance Science, St. Mary’s University, Twickenham, London, United Kingdom
| | - Malani Malumani
- HAND Research Group, School of Medicine and Health Sciences, Mulungushi University, Livingstone, Zambia
| | - Benson M. Hamooya
- HAND Research Group, School of Medicine and Health Sciences, Mulungushi University, Livingstone, Zambia
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Hahn RG, Patel V, Dull RO. Human glycocalyx shedding: Systematic review and critical appraisal. Acta Anaesthesiol Scand 2021; 65:590-606. [PMID: 33595101 DOI: 10.1111/aas.13797] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 01/28/2021] [Accepted: 02/01/2021] [Indexed: 02/06/2023]
Abstract
BACKGROUND The number of studies measuring breakdown products of the glycocalyx in plasma has increased rapidly during the past decade. The purpose of the present systematic review was to assess the current knowledge concerning the association between plasma concentrations of glycocalyx components and structural assessment of the endothelium. METHODS We performed a literature review of Pubmed to determine which glycocalyx components change in a wide variety of human diseases and conditions. We also searched for evidence of a relationship between plasma concentrations and the thickness of the endothelial glycocalyx layer as obtained by imaging methods. RESULTS Out of 3,454 publications, we identified 228 that met our inclusion criteria. The vast majority demonstrate an increase in plasma glycocalyx products. Sepsis and trauma are most frequently studied, and comprise approximately 40 publications. They usually report 3-4-foldt increased levels of glycocalyx degradation products, most commonly of syndecan-1. Surgery shows a variable picture. Cardiac surgery and transplantations are most likely to involve elevations of glycocalyx degradation products. Structural assessment using imaging methods show thinning of the endothelial glycocalyx layer in cardiovascular conditions and during major surgery, but thinning does not always correlate with the plasma concentrations of glycocalyx products. The few structural assessments performed do not currently support that capillary permeability is increased when the plasma levels of glycocalyx fragments in plasma are increased. CONCLUSIONS Shedding of glycocalyx components is a ubiquitous process that occurs during both acute and chronic inflammation with no sensitivity or specificity for a specific disease or condition.
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Affiliation(s)
- Robert G. Hahn
- Research UnitSödertälje Hospital Södertälje Sweden
- Karolinska Institute at Danderyds Hospital (KIDS) Stockholm Sweden
| | - Vasu Patel
- Department of Internal Medicine Northwestern Medicine McHenry Hospital McHenry IL USA
| | - Randal O. Dull
- Department of Anesthesiology, Pathology, Physiology, Surgery University of ArizonaCollege of Medicine Tucson AZ USA
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Dobrynina LA, Shabalina AA, Shamtieva KV, Krotenkova MV, Kalashnikova LA. [Salt sensitivity and osmotic fragility are newly specified risk factors for age-related cerebral microangiopathy]. Zh Nevrol Psikhiatr Im S S Korsakova 2021; 121:77-85. [PMID: 33834722 DOI: 10.17116/jnevro202112103177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
AIM/ To assess individual values of salt sensitivity and osmotic fragility on the patient's erythrocytes and evaluate predictive ability of these parameters in the development of cerebral small vessel disease (CSVD). MATERIAL AND METHODS The study included 73 patients with CSVD (48 women, mean age 60.1±6.5 years) and 19 volunteers (14 women, mean age 56.9±5.4 years). Their erythrocytes were used for the measurement of salt-sensitivity by a modified salt blood test and of osmotic fragility by the classical osmotic fragility test. Binary logistic regression was used to assess the ability of salt-sensitivity and osmotic fragility to predict CSVD development. ROC analysis was used to find out the optimal threshold values of these predictors, their sensitivity and specificity. RESULTS An increase in salt sensitivity (cut-off: 8.5 mm/h; sensitivity 64%, specificity 74%) and osmotic fragility (cut-off: 0.62 u.a.; sensitivity 52%, specificity 90%) or their simultaneous use (p of the model <0.000001, cut-off 0.62; sensitivity 88%, specificity 68%) are the independent predictors of CSVD. An increase in salt sensitivity and osmotic fragility is also independently associated with the acceleration of severity of white matter hyperintensities according to Fazekas stages (p=0.019 and 0.004, respectively). CONCLUSION The possibility of prediction of CSVD according to an increase in salt sensitivity and osmotic fragility allows us to consider them as the risk factors of CSVD. The standardization of these tests for use in clinical practice is necessary to identify the risk group for CSVD and its individual prevention.
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The Predictive Value of Salt Sensitivity and Osmotic Fragility in the Development of Cerebral Small Vessel Disease. Int J Mol Sci 2020; 21:ijms21062036. [PMID: 32188149 PMCID: PMC7139682 DOI: 10.3390/ijms21062036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/14/2020] [Accepted: 03/15/2020] [Indexed: 11/17/2022] Open
Abstract
Increased salt intake in food probably affects the progression of cerebral small vessel disease (CSVD), which justifies the study of disturbances in sodium homeostasis associated with the development of CSVD. We aimed to clarify the role of salt sensitivity and osmotic fragility in the development of CSVD. Erythrocyte salt sensitivity was measured using the modified salt blood test, and osmotic fragility was measured using the classic osmotic fragility test in 73 patients with CSVD (48 women; 60.1 ± 6.5 years) and 19 healthy volunteers (14 women; 56.9 ± 6.4 years). Salt sensitivity and osmotic fragility exhibited a predictive value in relation to CSVD. These parameters were associated with an increase in white matter hyperintensities (P = 0.019 and 0.004, respectively). Their simultaneous use increased their predictive ability for CSVD (P < 0.000001; AUC (95% CI), 0.824 (0.724-0.923)). The possibility of predicting CSVD using erythrocyte salt sensitivity and osmotic fragility indicates the value of the individual glycocalyx buffer capacity in relation to sodium and the activity of sodium channels in the development of CSVD. Increased salt sensitivity and osmotic fragility seem to be risk factors for CSVD.
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Vonend O, Martin O, Rump LC, Kroepil P, Stegbauer J. Erythrocyte Salt Sedimentation Assay Does Not Predict Response to Renal Denervation. Front Med (Lausanne) 2018; 5:51. [PMID: 29594117 PMCID: PMC5854684 DOI: 10.3389/fmed.2018.00051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 02/13/2018] [Indexed: 12/23/2022] Open
Abstract
Renal denervation (RDN) has recently been shown to be effective in patients without antihypertensive medication. However, about 30% of patients do not respond to RDN, and therefore, there exists a need to find predictors of response. Individuals are either salt-sensitive (SS) or non-salt-sensitive (NSS) in terms of their blood pressure (BP) regulation. The sympathetic nervous system can influence water and salt handling. RDN reduces sympathetic drive and has an impact on salt excretion. The present study was conducted to test the influence of salt sensitivity in terms of the BP reducing effect after RDN procedure. Salt sensitivity was estimated using the in vitro Erythrocyte Salt Sedimentation Assay (ESS). In 88 patients with resistant hypertension, RDN was performed. Office BP and lab testing were performed at baseline and at month 1, 3, 6, 12, 18, and 24 after RDN. A responder rate of 64.7% has been observed. Salt sensitivity measurements (ESS-Test) were completed in a subgroup of 37 patients with resistant hypertension. In this group, 15 were SS and 17 were salt-resistant according to the in vitro assay, respectively. The responder rate was 60% in SS patients and 59.1% in NSS patients, respectively. Electrolytes as well as aldosterone and renin levels did not differ between the two groups at baseline and in the follow-up measurements. The present study showed that salt sensitivity, estimated using the ESS in vitro test, did not affect the outcome of RDN and, therefore, does not help to identify patients suitable for RDN.
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Affiliation(s)
- Oliver Vonend
- Nierenzentrum, DKD Helios Klinik Wiesbaden, Wiesbaden, Germany.,Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Ole Martin
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Lars C Rump
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Patrick Kroepil
- Departement of Diagnostic and Interventional Radiology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Johannes Stegbauer
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
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Meyring-Wösten A, Kuntsevich V, Campos I, Williams S, Ma J, Patel S, Ornillo C, Thijssen S, Kotanko P. Erythrocyte Sodium Sensitivity and Eryptosis in Chronic Hemodialysis Patients. Kidney Blood Press Res 2017; 42:314-326. [DOI: 10.1159/000477608] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 03/07/2017] [Indexed: 11/19/2022] Open
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Oberleithner H, Wilhelmi M. Vascular Glycocalyx Sodium Store - Determinant of Salt Sensitivity? Blood Purif 2015; 39:7-10. [DOI: 10.1159/000368922] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Smart mechanisms allow frictionless slipping of rather rigid erythrocytes (red blood cells, RBC) through narrow blood vessels. Nature solved this problem in an elegant way coating the moving object (RBC) and the tunnel wall (endothelium) by negative charges (glycocalyx). As long as these surfaces are intact, repulsive forces create a ‘security zone' that keeps the respective surfaces separated from each other. However, damage of either one of these surfaces causes loss of negative charges, allowing an unfavorable physical interaction between the RBC and the endothelium. It has been recently shown that any alteration of the endothelial glycocalyx leaves nasty footprints on the RBC glycocalyx. In this scenario, sodium ions hold a prominent role. Plasma sodium is stored in the glycocalyx partially neutralizing the negative surface charges. A ‘good' glycocalyx has a high sodium store capacity but still maintains sufficient surface negativity at normal plasma sodium. A ‘bad' glycocalyx shows the opposite. This concept was used for the development of the so-called ‘salt blood test' (SBT) that quantitatively measures RBC sodium store capacity of the glycocalyx and thus indirectly evaluates the quality of the inner vessel wall. In an initial step, the applicability of the SBT was tested in eight different medical facilities. The study shows that an increased salt sensitivity, as measured by the SBT, is more frequently found in individuals with a hypertensive history, despite antihypertensive medication. Taken together, preservation of the endothelial glycocalyx appears to be of utmost importance for maintaining a well-balanced function of the vascular system.
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Oberleithner H. Sodium selective erythrocyte glycocalyx and salt sensitivity in man. Pflugers Arch 2014; 467:1319-25. [PMID: 25027385 PMCID: PMC4435639 DOI: 10.1007/s00424-014-1577-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 07/07/2014] [Indexed: 01/04/2023]
Abstract
Negatively charged surfaces of erythrocytes (RBC) reflect properties of the endothelial glycocalyx. Plasma electrolytes counteract these charges and thus control the repulsive forces between RBC and endothelium. Although Na+ is supposed to exert a rather high affinity to the RBC surface, a direct comparison between Na+ and K+ in counteracting the RBC surface has been never made. Therefore, we measured Na+/K+ selectivity of the RBC surface in 20 healthy volunteers applying the previously published salt blood test (SBT). It turned out that the Na+/K+ selectivity ratio of the RBC glycocalyx is on average 6.1 ± 0.39 (ranging from 3 to 9 in different individuals). Considering standard plasma Na+ and K+ concentrations, binding probability of Na+/K+ at the RBC surface is about 180:1. The SBT reveals that plasma K+ counteracts only about 7 % of the negative charges in the RBC glycocalyx. As an in vivo proof of principle, a volunteer’s blood was continuously tested over 6 months while applying a glycocalyx protective polyphenol-rich natural compound (hawthorn extract). It turned out that RBC Na+ sensitivity (the inverse of Na+ buffer capacity) decreased significantly by about 25 % while Na+/K+ selectivity of the RBC glycocalyx declined only slightly by about 8 %. Taken together, (i) plasma Na+ selectively buffers the negative charges of the RBC glycocalyx, (ii) the contribution of K+ in counteracting these negative surface charges is small, and (iii) natural polyphenols applied in vivo increase RBC surface negativity. In conclusion, low plasma Na+ is supposed to favor frictionless RBC-slipping through blood vessels.
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Affiliation(s)
- Hans Oberleithner
- Institute of Physiology II, University of Münster, Robert-Koch-Str. 27b, 48149, Münster, Germany,
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12
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Oberleithner H. Vascular endothelium: a vulnerable transit zone for merciless sodium. Nephrol Dial Transplant 2013; 29:240-6. [PMID: 24335504 DOI: 10.1093/ndt/gft461] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In humans, when plasma sodium concentration rises slightly beyond 140 mM, vascular endothelium sharply stiffens and nitric oxide release declines. In search of a vascular sodium sensor, the endothelial glycocalyx was identified as being a negatively charged biopolymer capable of selectively buffering sodium ions. Sodium excess damages the glycocalyx and renders vascular endothelium increasingly permeable for sodium. In the long term, sodium accumulates in the interstitium and gradually damages the organism. It was discovered that circulating red blood cells (RBC) 'report' surface properties of the vascular endothelium. To some extent, the RBC glycocalyx mirrors the endothelial glycocalyx. A poor (charge-deprived) endothelial glycocalyx causes a poor RBC glycocalyx and vice versa. This observation led to the assumption that the current state of an individual's vascular endothelium in terms of electrical surface charges and sodium-buffering capabilities could be read simply from a blood sample. Recently, a so-called salt blood test was introduced that quantifies the RBC sodium buffer capacity and thus characterizes the endothelial function. The arguments are outlined in this article spanning a bridge from cellular nano-mechanics to clinical application.
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Affiliation(s)
- Hans Oberleithner
- Institute of Physiology II, Medical Faculty, University of Münster, Münster 48149, Germany
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13
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Kusche-Vihrog K, Jeggle P, Oberleithner H. The role of ENaC in vascular endothelium. Pflugers Arch 2013; 466:851-9. [PMID: 24046153 DOI: 10.1007/s00424-013-1356-3] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 09/09/2013] [Accepted: 09/09/2013] [Indexed: 12/31/2022]
Abstract
Once upon a time, the expression of the epithelial sodium channel (ENaC) was mainly assigned to the kidneys, colon and sweat glands where it was considered to be the main determinant of sodium homeostasis. Recent, though indirect, evidence for the possible existence of ENaC in a non-epithelial tissue was derived from the observation that the vascular endothelium is a target for aldosterone. Inhibitory actions of the intracellular aldosterone receptors by spironolactone and, more directly, by ENaC blockers such as amiloride supported this view. Shortly after, direct data on the expression of ENaC in vascular endothelium could be demonstrated. There, endothelial ENaC (EnNaC) could be defined as a major regulator of cellular mechanics which is a critical parameter in differentiating between vascular function and dysfunction. Foremost, the mechanical stiffness of the endothelial cell cortex, a layer 50-200 nm beneath the plasma membrane, has been shown to play a crucial role as it controls the production of the endothelium-derived vasodilator nitric oxide (NO) which directly affects the tone of the vascular smooth muscle cells. In contrast to soft endothelial cells, stiff endothelial cells release reduced amounts of NO, the hallmark of endothelial dysfunction. Thus, the combination of endothelial stiffness and myogenic tone might increase the peripheral vascular resistance. An elevation of arterial blood pressure is supposed to be the consequence of such functional changes. In this review, EnNaC is discussed as an aldosterone-regulated plasma membrane protein of the vascular endothelium that could significantly contribute to maintaining of an appropriate arterial blood pressure but, if overexpressed, could participate in the pathogenesis of arterial hypertension.
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Affiliation(s)
- Kristina Kusche-Vihrog
- Institute of Physiology II, University of Münster, Robert-Koch-Str. 27b, 48149, Münster, Germany,
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