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Gao S, Cui X, Wang X, Burg MB, Dmitrieva NI. Cross-Sectional Positive Association of Serum Lipids and Blood Pressure With Serum Sodium Within the Normal Reference Range of 135-145 mmol/L. Arterioscler Thromb Vasc Biol 2016; 37:598-606. [PMID: 28062505 DOI: 10.1161/atvbaha.116.308413] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Accepted: 12/08/2016] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Serum sodium concentration is maintained by osmoregulation within normal range of 135 to 145 mmol/L. Previous analysis of data from the ARIC study (Atherosclerosis Risk in Communities) showed association of serum sodium with the 10-year risk scores of coronary heart disease and stroke. Current study evaluated the association of within-normal-range serum sodium with cardiovascular risk factors. APPROACH AND RESULTS Only participants who did not take cholesterol or blood pressure medications and had sodium within normal 135 to 145 mmol/L range were included (n=8615), and the cohort was stratified based on race, sex, and smoking status. Multiple linear regression analysis of data from ARIC study was performed, with adjustment for age, blood glucose, insulin, glomerular filtration rate, body mass index, waist to hip ratio, and calorie intake. The analysis showed positive associations with sodium of total cholesterol, low-density lipoprotein cholesterol, and total cholesterol to high-density lipoprotein cholesterol ratio; apolipoprotein B; and systolic and diastolic blood pressure. Increases in lipids and blood pressure associated with 10 mmol/L increase in sodium are similar to the increases associated with 7 to 10 years of aging. Analysis of sodium measurements made 3 years apart demonstrated that it is stable within 2 to 3 mmol/L, explaining its association with long-term health outcomes. Furthermore, elevated sodium promoted lipid accumulation in cultured adipocytes, suggesting direct causative effects on lipid metabolism. CONCLUSIONS Serum sodium concentration is a cardiovascular risk factor even within the normal reference range. Thus, decreasing sodium to the lower end of the normal range by modification of water and salt intake is a personalizable strategy for decreasing cardiovascular risks.
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Affiliation(s)
- Shouguo Gao
- From the Bioinformatics and Systems Biology Core, Systems Biology Center (S.G., X.W.), Renal Cellular and Molecular Biology Section, Systems Biology Center (M.B.B., N.I.D.), and Laboratory of Cardiovascular and Regenerative Medicine, Center for Molecular Medicine (N.I.D.), National Heart, Lung and Blood Institute, Bethesda, MD; and Department of Biostatistics, University of Alabama at Birmingham (X.C.)
| | - Xiangqin Cui
- From the Bioinformatics and Systems Biology Core, Systems Biology Center (S.G., X.W.), Renal Cellular and Molecular Biology Section, Systems Biology Center (M.B.B., N.I.D.), and Laboratory of Cardiovascular and Regenerative Medicine, Center for Molecular Medicine (N.I.D.), National Heart, Lung and Blood Institute, Bethesda, MD; and Department of Biostatistics, University of Alabama at Birmingham (X.C.)
| | - Xujing Wang
- From the Bioinformatics and Systems Biology Core, Systems Biology Center (S.G., X.W.), Renal Cellular and Molecular Biology Section, Systems Biology Center (M.B.B., N.I.D.), and Laboratory of Cardiovascular and Regenerative Medicine, Center for Molecular Medicine (N.I.D.), National Heart, Lung and Blood Institute, Bethesda, MD; and Department of Biostatistics, University of Alabama at Birmingham (X.C.)
| | - Maurice B Burg
- From the Bioinformatics and Systems Biology Core, Systems Biology Center (S.G., X.W.), Renal Cellular and Molecular Biology Section, Systems Biology Center (M.B.B., N.I.D.), and Laboratory of Cardiovascular and Regenerative Medicine, Center for Molecular Medicine (N.I.D.), National Heart, Lung and Blood Institute, Bethesda, MD; and Department of Biostatistics, University of Alabama at Birmingham (X.C.)
| | - Natalia I Dmitrieva
- From the Bioinformatics and Systems Biology Core, Systems Biology Center (S.G., X.W.), Renal Cellular and Molecular Biology Section, Systems Biology Center (M.B.B., N.I.D.), and Laboratory of Cardiovascular and Regenerative Medicine, Center for Molecular Medicine (N.I.D.), National Heart, Lung and Blood Institute, Bethesda, MD; and Department of Biostatistics, University of Alabama at Birmingham (X.C.).
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Kinsman BJ, Simmonds SS, Browning KN, Stocker SD. Organum Vasculosum of the Lamina Terminalis Detects NaCl to Elevate Sympathetic Nerve Activity and Blood Pressure. Hypertension 2016; 69:163-170. [PMID: 27895193 DOI: 10.1161/hypertensionaha.116.08372] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 09/07/2016] [Accepted: 10/31/2016] [Indexed: 02/05/2023]
Abstract
High-salt diet elevates NaCl concentrations in the cerebrospinal fluid to increase sympathetic nerve activity (SNA) in salt-sensitive hypertension. The organum vasculosum of the lamina terminalis (OVLT) resides along the rostral wall of the third ventricle, lacks a complete blood-brain barrier, and plays a pivotal role in body fluid homeostasis. Therefore, the present study used a multifaceted approach to examine whether OVLT neurons of Sprague-Dawley rats are intrinsically sensitive to changes in extracellular NaCl concentrations and mediate the sympathoexcitatory responses to central NaCl loading. Using in vitro whole-cell recordings, step-wise increases in extracellular NaCl concentrations (2.5-10 mmol/L) produced concentration-dependent excitation of OVLT neurons. Additionally, these excitatory responses were intrinsic to OVLT neurons because hypertonic NaCl evoked inward currents, despite pharmacological synaptic blockade. In vivo single-unit recordings demonstrate that the majority of OVLT neurons (72%, 13/19) display concentration-dependent increases in neuronal discharge to intracarotid (50 μL/15 s) or intracerebroventricular infusion (5 μL/10 minutes) of hypertonic NaCl. Microinjection of hypertonic NaCl (30 nL/60 s) into the OVLT, but not adjacent areas, increased lumbar SNA, adrenal SNA, and arterial blood pressure in a concentration-dependent manner. Renal SNA decreased and splanchnic SNA remained unaffected. Finally, local inhibition of OVLT neurons with the GABAA receptor agonist muscimol (24 nL/10 s) significantly attenuated the sympathoexcitatory and pressor responses to intracerebroventricular infusion of 0.5 mol/L or 1.0 mol/L NaCl. Collectively, these findings indicate that OVLT neurons detect changes in extracellular NaCl concentrations to selectively alter SNA and raise arterial blood pressure.
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Affiliation(s)
- Brian J Kinsman
- From the Department of Medicine, Division of Renal-Electrolyte, University of Pittsburgh School of Medicine, PA (B.J.K., S.D.S.); and Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA (B.J.K., S.S.S., K.N.B.)
| | - Sarah S Simmonds
- From the Department of Medicine, Division of Renal-Electrolyte, University of Pittsburgh School of Medicine, PA (B.J.K., S.D.S.); and Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA (B.J.K., S.S.S., K.N.B.)
| | - Kirsteen N Browning
- From the Department of Medicine, Division of Renal-Electrolyte, University of Pittsburgh School of Medicine, PA (B.J.K., S.D.S.); and Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA (B.J.K., S.S.S., K.N.B.)
| | - Sean D Stocker
- From the Department of Medicine, Division of Renal-Electrolyte, University of Pittsburgh School of Medicine, PA (B.J.K., S.D.S.); and Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA (B.J.K., S.S.S., K.N.B.).
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P2Y1 Receptor Signaling Contributes to High Salt-Induced Priming of the NLRP3 Inflammasome in Retinal Pigment Epithelial Cells. PLoS One 2016; 11:e0165653. [PMID: 27788256 PMCID: PMC5082949 DOI: 10.1371/journal.pone.0165653] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 10/14/2016] [Indexed: 12/13/2022] Open
Abstract
Background Systemic hypertension is a risk factor of age-related macular degeneration (AMD), a chronic inflammatory disease. Acute hypertension is caused by increased extracellular osmolarity after intake of dietary salt (NaCl). We determined in cultured human retinal pigment epithelial (RPE) cells whether high extracellular NaCl alters the gene expression of inflammasome-associated proteins, and whether autocrine/paracrine purinergic (P2) receptor signaling contributes to the NaCl-induced NLRP3 gene expression. Methodology/Principal Findings Hyperosmolarity was induced by the addition of 100 mM NaCl or sucrose to the culture medium. Gene and protein expression levels were determined with real-time RT-PCR and Western blot analysis, respectively. IL-1β and IL-18 levels were evaluated with ELISA. Nuclear factor of activated T cell 5 (NFAT5) expression was knocked down with siRNA. High extracellular NaCl induced NLRP3 and pro-IL-1β gene expression, while the gene expression of further inflammasome-associated proteins (NLRP1, NLRP2, NLRP6, NLRP7, NLRP12, NLRC4, AIM2, ASC, procaspase-1, pro-IL-18) was not altered or below the detection threshold. The NaCl-induced NLRP3 gene expression was partially dependent on the activities of phospholipase C, IP3 receptors, protein kinase C, the serum and glucocorticoid-regulated kinase, p38 MAPK, ERK1/2, JNK, PI3K, and the transcription factors HIF-1 and NFAT5. Pannexin-dependent ATP release and P2Y1 receptor activation is required for the full induction of NLRP3 gene expression. High NaCl induced a transient increase of the NLRP3 protein level and a moderate NLRP3 inflammasome activation, as indicated by the transient increase of the cytosolic level of mature IL-1β. High NaCl also induced secretion of IL-18. Conclusion High extracellular NaCl induces priming of the NLRP3 inflammasome in RPE cells, in part via P2Y1 receptor signaling. The inflammasome priming effect of NaCl suggests that high intake of dietary salt may promote local retinal inflammation implicated in the development of AMD.
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Winges A, Garcia TB, Prager P, Wiedemann P, Kohen L, Bringmann A, Hollborn M. Osmotic expression of aldose reductase in retinal pigment epithelial cells: involvement of NFAT5. Graefes Arch Clin Exp Ophthalmol 2016; 254:2387-2400. [PMID: 27628063 DOI: 10.1007/s00417-016-3492-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 08/22/2016] [Accepted: 08/29/2016] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Diabetic retinopathy is associated with osmotic stress resulting from hyperglycemia and intracellular sorbitol accumulation. Systemic hypertension is a risk factor of diabetic retinopathy. High intake of dietary salt increases extracellular osmolarity resulting in systemic hypertension. We determined the effects of extracellular hyperosmolarity, chemical hypoxia, and oxidative stress on the gene expression of enzymes involved in sorbitol production and conversion in cultured human retinal pigment epithelial (RPE) cells. METHODS Alterations in the expression of aldose reductase (AR) and sorbitol dehydrogenase (SDH) genes were examined with real-time RT-PCR. Protein levels were determined with Western blot analysis. Nuclear factor of activated T cell 5 (NFAT5) was knocked down with siRNA. RESULTS AR gene expression in RPE cells was increased by high (25 mM) extracellular glucose, CoCl2 (150 μM)-induced chemical hypoxia, H2O2 (20 μM)-induced oxidative stress, and extracellular hyperosmolarity induced by addition of NaCl or sucrose. Extracellular hyperosmolarity (but not hypoxia) also increased AR protein level. SDH gene expression was increased by hypoxia and oxidative stress, but not extracellular hyperosmolarity. Hyperosmolarity and hypoxia did not alter the SDH protein level. The hyperosmotic AR gene expression was dependent on activation of metalloproteinases, autocrine/paracrine TGF-β signaling, activation of p38 MAPK, ERK1/2, and PI3K signal transduction pathways, and the transcriptional activity of NFAT5. Knockdown of NAFT5 or inhibition of AR decreased the cell viability under hyperosmotic (but not hypoxic) conditions and aggravated the hyperosmotic inhibition of cell proliferation. CONCLUSIONS The data suggest that sorbitol accumulation in RPE cells occurs under hyperosmotic, but not hypoxic and oxidative stress conditions. NFAT5- and AR-mediated sorbitol accumulation may protect RPE cells under conditions of osmotic stress.
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Affiliation(s)
- Anica Winges
- Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of Leipzig, Liebigstrasse 10-14, D-04103, Leipzig, Germany
| | - Tarcyane Barata Garcia
- Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of Leipzig, Liebigstrasse 10-14, D-04103, Leipzig, Germany
| | - Philipp Prager
- Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of Leipzig, Liebigstrasse 10-14, D-04103, Leipzig, Germany
| | - Peter Wiedemann
- Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of Leipzig, Liebigstrasse 10-14, D-04103, Leipzig, Germany
| | - Leon Kohen
- Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of Leipzig, Liebigstrasse 10-14, D-04103, Leipzig, Germany
- Helios Klinikum Aue, Aue, Germany
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of Leipzig, Liebigstrasse 10-14, D-04103, Leipzig, Germany
| | - Margrit Hollborn
- Department of Ophthalmology and Eye Hospital, Faculty of Medicine, University of Leipzig, Liebigstrasse 10-14, D-04103, Leipzig, Germany.
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AMP-Activated Protein Kinase Attenuates High Salt-Induced Activation of Epithelial Sodium Channels (ENaC) in Human Umbilical Vein Endothelial Cells. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:1531392. [PMID: 27635187 PMCID: PMC5011216 DOI: 10.1155/2016/1531392] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 06/16/2016] [Indexed: 02/05/2023]
Abstract
Recent studies suggest that the epithelial sodium channel (ENaC) is expressed in the endothelial cells. To test whether high salt affects the NO production via regulation of endothelial ENaC, human umbilical vein endothelial cells (HUVECs) were incubated in solutions containing either normal or high sodium (additional 20 mM NaCl). Our data showed that high sodium treatment significantly increased α-, β-, and γ-ENaC expression levels in HUVECs. Using the cell-attached patch-clamp technique, we demonstrated that high sodium treatment significantly increased ENaC open probability (PO). Moreover, nitric oxide synthase (eNOS) phosphorylation (Ser 1177) levels and NO production were significantly decreased by high sodium in HUVECs; the effects of high sodium on eNOS phosphorylation and NO production were inhibited by a specific ENaC blocker, amiloride. Our results showed that high sodium decreased AMP-activated kinase (AMPK) phosphorylation in endothelial cells. On the other hand, metformin, an AMPK activator, prevented high sodium-induced upregulation of ENaC expression and PO. Moreover, metformin prevented high salt-induced decrease in NO production and eNOS phosphorylation. These results suggest that high sodium stimulates ENaC activation by negatively modulating AMPK activity, thereby leading to reduction in eNOS activity and NO production in endothelial cells.
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Olde Engberink RHG, Heerspink HJL, de Zeeuw D, Vogt L. Blood pressure-lowering effects of sulodexide depend on albuminuria severity: post hoc analysis of the sulodexide microalbuminuria and macroalbuminuria studies. Br J Clin Pharmacol 2016; 82:1351-1357. [PMID: 27412828 PMCID: PMC5061782 DOI: 10.1111/bcp.13062] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 06/01/2016] [Accepted: 07/11/2016] [Indexed: 11/28/2022] Open
Abstract
Aims It has been suggested that sulodexide is able to lower blood pressure (BP). This may be attributed to its ability to restore the endothelial surface layer (ESL). As ESL perturbation is known to be related to the degree of kidney damage, we investigated whether albuminuria, reflecting ESL status, modified the BP‐lowering potential of sulodexide. Methods A post hoc analysis of the double‐blind, randomized, placebo‐controlled sulodexide microalbuminuria (Sun‐MICRO) and macroalbuminuria (Sun‐MACRO) studies, including 1056 microalbuminuric and 843 macroalbuminuric subjects with type 2 diabetes receiving maximal tolerated renin–angiotensin‐aldosterone system inhibitor therapy, was carried out. We compared the effect of placebo and sulodexide on systolic BP (SBP) among albuminuria groups. Results Analysis of covariance, including data from both trials, showed that baseline urine albumin‐to‐creatinine ratio (UACR) was the only modifier of the SBP response (interaction with treatment P = 0.001). In subjects with an UACR >1000 mg g–1, sulodexide lowered SBP by 4.6 mmHg [95% confidence interval (CI) 3.6, 5.6; P < 0.001] compared with placebo, whereas a 2.3 mmHg (95% CI 0.9,3.7; P = 0.001) reduction was seen in subjects with a UACR of 300–1000 mg g–1. Sulodexide did not lower SBP in subjects with a UACR <300 mg g–1 (−0.2 mmHg, 95% CI −0.8, 0.5; P = 0.60). SBP‐lowering effects were not accompanied by changes in body weight. Conclusion The BP‐reducing potency of sulodexide is modified by the degree of albuminuria in subjects with type 2 diabetes. As ESL status deteriorates with increasing albuminuria and nephropathy severity, this suggests that ESL restoration may represent a new target for BP treatment in subjects with diabetic nephropathy.
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Affiliation(s)
- Rik H G Olde Engberink
- Department of Internal Medicine, Division of Nephrology, University of Amsterdam, Academic Medical Center, Amsterdam, the Netherlands.
| | - Hiddo J L Heerspink
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, Groningen, the Netherlands
| | - Dick de Zeeuw
- Department of Clinical Pharmacy and Pharmacology, University Medical Center Groningen, Groningen, the Netherlands
| | - Liffert Vogt
- Department of Internal Medicine, Division of Nephrology, University of Amsterdam, Academic Medical Center, Amsterdam, the Netherlands
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Morris RC, Schmidlin O, Sebastian A, Tanaka M, Kurtz TW. Vasodysfunction That Involves Renal Vasodysfunction, Not Abnormally Increased Renal Retention of Sodium, Accounts for the Initiation of Salt-Induced Hypertension. Circulation 2016; 133:881-93. [PMID: 26927006 DOI: 10.1161/circulationaha.115.017923] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- R Curtis Morris
- From the Departments of Medicine (R.C.M., O.S., A.S., M.T.) and Laboratory Medicine (T.W.K.), University of California, San Francisco.
| | - Olga Schmidlin
- From the Departments of Medicine (R.C.M., O.S., A.S., M.T.) and Laboratory Medicine (T.W.K.), University of California, San Francisco
| | - Anthony Sebastian
- From the Departments of Medicine (R.C.M., O.S., A.S., M.T.) and Laboratory Medicine (T.W.K.), University of California, San Francisco
| | - Masae Tanaka
- From the Departments of Medicine (R.C.M., O.S., A.S., M.T.) and Laboratory Medicine (T.W.K.), University of California, San Francisco
| | - Theodore W Kurtz
- From the Departments of Medicine (R.C.M., O.S., A.S., M.T.) and Laboratory Medicine (T.W.K.), University of California, San Francisco.
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Cao Y, Fang Y, Mu J, Liu X. High salt medium activates RhoA/ROCK and downregulates eNOS expression via the upregulation of ADMA. Mol Med Rep 2016; 14:606-12. [PMID: 27175806 DOI: 10.3892/mmr.2016.5241] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 04/18/2016] [Indexed: 11/05/2022] Open
Abstract
Endothelial dysfunction has an important role in the development and progression of salt-sensitive hypertension. Asymmetric dimethylarginine (ADMA), which is an endogenous inhibitor of nitric oxide synthase (NOS), has been demonstrated to be involved in the pathophysiological processes of endothelial dysfunction and salt‑sensitive hypertension. However, it is currently unclear how high salt intake may induce these processes. The present study investigated the effects of high salt medium on ADMA, endothelial NOS (eNOS) and the Ras homolog gene family, member A (RhoA)/Rho-associated protein kinase (ROCK) pathway in the EA.hy926 umbilical vein cell line. The results demonstrated that high salt medium significantly increased the concentration of ADMA, the expression of protein arginine methyltransferase 1 (PRMT‑1) and RhoA, and the activity of ROCK, and downregulated the expression of eNOS. Knockdown of PRMT-1 with small interfering RNA (siRNA) significantly abrogated the aforementioned effects. These results indicated that ADMA has a key role in high salt‑mediated activation of the RhoA/ROCK pathway and inhibition of eNOS biosynthesis. siRNA‑PRMT‑1 may be considered a novel remedy for the treatment of endothelial dysfunction.
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Affiliation(s)
- Yu Cao
- Department of Pediatrics, First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Yuan Fang
- Department of Cardiovascular Medicine, First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Jianjun Mu
- Department of Cardiovascular Medicine, First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Xiaohong Liu
- Department of Pediatrics, First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
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Farquhar WB, Edwards DG, Jurkovitz CT, Weintraub WS. Dietary sodium and health: more than just blood pressure. J Am Coll Cardiol 2016; 65:1042-50. [PMID: 25766952 DOI: 10.1016/j.jacc.2014.12.039] [Citation(s) in RCA: 188] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 12/09/2014] [Accepted: 12/16/2014] [Indexed: 12/24/2022]
Abstract
Sodium is essential for cellular homeostasis and physiological function. Excess dietary sodium has been linked to elevations in blood pressure (BP). Salt sensitivity of BP varies widely, but certain subgroups tend to be more salt sensitive. The mechanisms underlying sodium-induced increases in BP are not completely understood but may involve alterations in renal function, fluid volume, fluid-regulatory hormones, the vasculature, cardiac function, and the autonomic nervous system. Recent pre-clinical and clinical data support that even in the absence of an increase in BP, excess dietary sodium can adversely affect target organs, including the blood vessels, heart, kidneys, and brain. In this review, the investigators review these issues and the epidemiological research relating dietary sodium to BP and cardiovascular health outcomes, addressing recent controversies. They also provide information and strategies for reducing dietary sodium.
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Affiliation(s)
- William B Farquhar
- Department of Kinesiology & Applied Physiology, College of Health Sciences, University of Delaware, Newark, Delaware
| | - David G Edwards
- Department of Kinesiology & Applied Physiology, College of Health Sciences, University of Delaware, Newark, Delaware
| | - Claudine T Jurkovitz
- Department of Medicine, Section of Cardiology, Christiana Care Outcomes Research Center, Christiana Care Health System, Newark, Delaware
| | - William S Weintraub
- Department of Medicine, Section of Cardiology, Christiana Care Outcomes Research Center, Christiana Care Health System, Newark, Delaware.
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Osmotic Induction of Angiogenic Growth Factor Expression in Human Retinal Pigment Epithelial Cells. PLoS One 2016; 11:e0147312. [PMID: 26800359 PMCID: PMC4723123 DOI: 10.1371/journal.pone.0147312] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 12/31/2015] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Although systemic hypertension is a risk factor of age-related macular degeneration, antihypertensive medications do not affect the risk of the disease. One condition that induces hypertension is high intake of dietary salt resulting in increased blood osmolarity. In order to prove the assumption that, in addition to hypertension, high osmolarity may aggravate neovascular retinal diseases, we determined the effect of extracellular hyperosmolarity on the expression of angiogenic cytokines in cultured human retinal pigment epithelial (RPE) cells. METHODOLOGY/PRINCIPAL FINDINGS Hyperosmolarity was induced by the addition of 100 mM NaCl or sucrose to the culture medium. Hypoxia and oxidative stress were induced by the addition of the hypoxia mimetic CoCl2 and H2O2, respectively. Alterations in gene expression were determined with real-time RT-PCR. Secretion of bFGF was evaluated by ELISA. Cell viability was determined by trypan blue exclusion. Nuclear factor of activated T cell 5 (NFAT5) expression was knocked down with siRNA. Hyperosmolarity induced transcriptional activation of bFGF, HB-EGF, and VEGF genes, while the expression of other cytokines such as EGF, PDGF-A, TGF-β1, HGF, and PEDF was not or moderately altered. Hypoxia induced increased expression of the HB-EGF, EGF, PDGF-A, TGF-β1, and VEGF genes, but not of the bFGF gene. Oxidative stress induced gene expression of HB-EGF, but not of bFGF. The hyperosmotic expression of the bFGF gene was dependent on the activation of p38α/β MAPK, JNK, PI3K, and the transcriptional activity of NFAT5. The hyperosmotic expression of the HB-EGF gene was dependent on the activation of p38α/β MAPK, ERK1/2, and JNK. The hyperosmotic expression of bFGF, HB-EGF, and VEGF genes was reduced by inhibitors of TGF-β1 superfamily activin receptor-like kinase receptors and the FGF receptor kinase, respectively. Hyperosmolarity induced secretion of bFGF that was reduced by inhibition of autocrine/paracrine TGF-β1 signaling and by NFAT5 siRNA, respectively. Hyperosmolarity decreased the viability of the cells; this effect was not altered by exogenous bFGF and HB-EGF. Various vegetable polyphenols (luteolin, quercetin, apigenin) inhibited the hyperosmotic expression of bFGF, HB-EGF, and NFAT5 genes. CONCLUSION Hyperosmolarity induces transcription of bFGF and HB-EGF genes, and secretion of bFGF from RPE cells. This is in part mediated by autocrine/paracrine TGF-β1 and FGF signaling. It is suggested that high intake of dietary salt resulting in osmotic stress may aggravate neovascular retinal diseases via stimulation of the production of angiogenic factors in RPE cells, independent of hypertension.
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Wannamethee SG, Shaper AG, Lennon L, Papacosta O, Whincup P. Mild hyponatremia, hypernatremia and incident cardiovascular disease and mortality in older men: A population-based cohort study. Nutr Metab Cardiovasc Dis 2016; 26:12-19. [PMID: 26298426 PMCID: PMC4714622 DOI: 10.1016/j.numecd.2015.07.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 07/02/2015] [Accepted: 07/21/2015] [Indexed: 12/17/2022]
Abstract
AIM To examine the association between serum sodium concentration and incident major cardiovascular disease (CVD) outcomes and total mortality in older men. METHODS AND RESULTS A prospective study of 3099 men aged 60-79 years without a history of cardiovascular disease followed up for an average 11 years during which there were 528 major CVD events (fatal coronary heart disease [CHD] and non-fatal MI, stroke and CVD death) and 873 total deaths. A U shaped relationship was seen between serum sodium concentration and major CVD events and mortality. Hyponatremia (<136 mEq/L) and low sodium within the normal range (136-138 mEq/L) showed significantly increased risk of major CVD events and total mortality compared to men within the upper normal range (139-143 mEq/L) after adjustment for a wide range of confounders and traditional risk factors [adjusted HRs 1.55 (1.13,2.12) and 1.40 (1.14,1.72) for major CVD events respectively and 1.30 (1.02,1.66) and 1.30 (1.11,1.53) respectively for total mortality]. Hyponatremia was associated with inflammation, NT-proBNP, low muscle mass and alkaline phosphatase; these factors contributed to the increased total mortality associated with hyponatremia but did not explain the increased risk of CVD events associated with hyponatremia or low normal sodium concentration. Hypernatremia (≥145 mEq/L) was associated with significantly increased risk of CVD events and mortality due to CVD causes. CONCLUSION Mild hyponatremia even within the normal sodium range and hypernatremia are both associated with increased total mortality and major CVD events in older men without CVD which is not explained by known adverse CV risk factors.
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Affiliation(s)
- S G Wannamethee
- Department of Primary Care and Population Health, UCL, London, UK.
| | - A G Shaper
- Department of Primary Care and Population Health, UCL, London, UK
| | - L Lennon
- Department of Primary Care and Population Health, UCL, London, UK
| | - O Papacosta
- Department of Primary Care and Population Health, UCL, London, UK
| | - P Whincup
- Department of Population Health Sciences and Education, St George's, University of London, UK
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Nakajima K, Oda E, Kanda E. The association of serum sodium and chloride levels with blood pressure and estimated glomerular filtration rate. Blood Press 2015; 25:51-7. [PMID: 26434759 DOI: 10.3109/08037051.2015.1090711] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND High serum sodium (sNa) concentrations may be associated with hypertension, which deteriorates kidney function. However, it is equivocal whether high sNa concentrations are associated with impaired kidney function independently of blood pressure (BP) or serum chloride (sCl). Therefore, we addressed this issue in an apparently healthy population. METHODS Clinical variables including estimated glomerular filtration rate (eGFR) were examined in 3603 men and women (aged 25-75 years) who underwent health-screening check-ups. sNa concentrations were classified into five categories. RESULTS Most parameters, including age and BP, increased with increasing sNa, whereas eGFR decreased. Logistic regression analysis showed that, compared with low-normal sNa (≤ 140 mEq/l), high sNa (≥ 144 mEq/l) was significantly associated with elevated BP (≥ 130/85 mmHg) even after adjustment for blood hematocrit, eGFR, serum potassium (sK) concentration and sCl. The highest sNa category was significantly associated with reduced eGFR (< 60 ml/min/1.73 m(2)) independently of elevated BP. Unlike adjustment for sK, adjustment for sCl strengthened the association between high sNa and elevated BP but attenuated the association between high sNa and reduced eGFR. CONCLUSIONS These results suggest that high sNa concentrations, even within the normal range, are independently associated with elevated BP and impaired kidney function. These associations may be substantially modified by sCl.
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Affiliation(s)
- Kei Nakajima
- a Division of Clinical Nutrition, Department of Medical Dietetics , Faculty of Pharmaceutical Sciences, Josai University , Sakado, Saitama , Japan.,b Department of Metabolism , Kuki General Hospital , Kuki, Saitama , Japan
| | - Eiji Oda
- c Medical Check-up Center, Tachikawa Medical Center , Nagaoka, Niigata , Japan
| | - Eiichiro Kanda
- d Department of Nephrology , Tokyo Kyosai Hospital , Meguro-ku, Tokyo , Japan
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63
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Abstract
High salt intake is the major cause of raised blood pressure and accordingly leads to cardiovascular diseases. Recently, it has been shown that high salt intake is associated with an increased risk of obesity through sugar-sweetened beverage consumption. Increasing evidence also suggests a direct link. Our study aimed to determine whether there was a direct association between salt intake and obesity independent of energy intake. We analyzed the data from the rolling cross-sectional study–the UK National Diet and Nutrition Survey 2008/2009 to 2011/2012. We included 458 children (52% boys; age, 10±4 years) and 785 adults (47% men; age, 49±17 years) who had complete 24-hour urine collections. Energy intake was calculated from 4-day diary and misreporting was assessed by Goldberg method. The results showed that salt intake as measured by 24-hour urinary sodium was higher in overweight and obese individuals. A 1-g/d increase in salt intake was associated with an increase in the risk of obesity by 28% (odds ratio, 1.28; 95% confidence interval, 1.12–1.45;
P
=0.0002) in children and 26% (odds ratio, 1.26; 95% confidence interval, 1.16–1.37;
P
<0.0001) in adults, after adjusting for age, sex, ethnic group, household income, physical activity, energy intake, and diet misreporting, and in adults with additional adjustment for education, smoking, and alcohol consumption. Higher salt intake was also significantly related to higher body fat mass in both children (
P
=0.001) and adults (
P
=0.001) after adjusting for age, sex, ethnic group, and energy intake. These results suggest that salt intake is a potential risk factor for obesity independent of energy intake.
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Affiliation(s)
- Yuan Ma
- From the Center for Environmental and Preventive Medicine, Wolfson Institute of Preventive Medicine, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom (Y.M., F.J.H., G.A.M.); and Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing, China (Y.M.)
| | - Feng J. He
- From the Center for Environmental and Preventive Medicine, Wolfson Institute of Preventive Medicine, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom (Y.M., F.J.H., G.A.M.); and Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing, China (Y.M.)
| | - Graham A. MacGregor
- From the Center for Environmental and Preventive Medicine, Wolfson Institute of Preventive Medicine, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom (Y.M., F.J.H., G.A.M.); and Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing, China (Y.M.)
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64
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Ribeiro N, Panizza HDN, Santos KMD, Ferreira-Neto HC, Antunes VR. Salt-induced sympathoexcitation involves vasopressin V1a receptor activation in the paraventricular nucleus of the hypothalamus. Am J Physiol Regul Integr Comp Physiol 2015; 309:R1369-79. [PMID: 26354848 DOI: 10.1152/ajpregu.00312.2015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 08/31/2015] [Indexed: 11/22/2022]
Abstract
A high-salt diet can lead to hydromineral imbalance and increases in plasma sodium and osmolality. It is recognized as one of the major contributing factors for cardiovascular diseases such as hypertension. The paraventricular nucleus (PVN) plays a pivotal role in osmotically driven sympathoexcitation and high blood pressure, the precise mechanisms of which are not fully understood. Recent evidence indicates that AVP released from magnocellular neurons might be involved in this process. Using a combination of in vivo and in situ studies, we sought to investigate whether AVP, acting on PVN neurons, can change mean arterial pressure (MAP) and sympathetic nerve activity (SNA) in euhydrated male rats. Furthermore, we wanted to determine whether V1a receptors on PVN neurons would be involved in salt-induced sympathoexcitation and hypertension. In rats, 4 days of salt loading (NaCl 2%) elicited a significant increase in plasma osmolality (39 ± 7 mosmol/kgH2O), an increase in MAP (26 ± 2 mmHg, P < 0.001), and sympathoexcitation compared with euhydrated rats. Microinjection of AVP into the PVN of conscious euhydrated animals (100 nl, 3 μM) elicited a pressor response (14 ± 2 mmHg) and a significant increase in lumbar SNA (100 nl, 1 mM) (19 ± 5%). Pretreatment with a V1a receptor antagonist, microinjected bilaterally into the PVN of salt-loaded animals, elicited a decrease in lumbar SNA (-14 ± 5%) and MAP (-19 ± 5 mmHg), when compared with the euhydrated group. Our findings show that AVP plays an important role in modulating the salt-induced sympathoexcitation and high blood pressure, via V1a receptors, within the PVN of male rats. As such, V1a receptors in the PVN might contribute to neurogenic hypertension in individuals consuming a high-salt diet.
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Affiliation(s)
- Natalia Ribeiro
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Helena do Nascimento Panizza
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Karoline Martins Dos Santos
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Hildebrando C Ferreira-Neto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Vagner Roberto Antunes
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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65
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Carmichael CY, Wainford RD. Brain Gαi 2 -subunit proteins and the prevention of salt sensitive hypertension. Front Physiol 2015; 6:233. [PMID: 26347659 PMCID: PMC4541027 DOI: 10.3389/fphys.2015.00233] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 08/03/2015] [Indexed: 12/19/2022] Open
Abstract
To counter the development of salt-sensitive hypertension, multiple brain G-protein-coupled receptor (GPCR) systems are activated to facilitate sympathoinhibition, sodium homeostasis, and normotension. Currently there is a paucity of knowledge regarding the role of down-stream GPCR-activated Gα-subunit proteins in these critically important physiological regulatory responses required for long-term blood pressure regulation. We have determined that brain Gαi2-proteins mediate natriuretic and sympathoinhibitory responses produced by acute pharmacological (exogenous central nociceptin/orphanin FQ receptor (NOP) and α2-adrenoceptor activation) and physiological challenges to sodium homeostasis (intravenous volume expansion and 1 M sodium load) in conscious Sprague–Dawley rats. We have demonstrated that in salt-resistant rat phenotypes, high dietary salt intake evokes site-specific up-regulation of hypothalamic paraventricular nucleus (PVN) Gαi2-proteins. Further, we established that PVN Gαi2 protein up-regulation prevents the development of renal nerve-dependent sympathetically mediated salt-sensitive hypertension in Sprague–Dawley and Dahl salt-resistant rats. Additionally, failure to up-regulate PVN Gαi2 proteins during high salt-intake contributes to the pathophysiology of Dahl salt-sensitive (DSS) hypertension. Collectively, our data demonstrate that brain, and likely PVN specific, Gαi2 protein pathways represent a central molecular pathway mediating sympathoinhibitory renal-nerve dependent responses evoked to maintain sodium homeostasis and a salt-resistant phenotype. Further, impairment of this endogenous “anti-hypertensive” mechanism contributes to the pathophysiology of salt-sensitive hypertension.
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Affiliation(s)
- Casey Y Carmichael
- The Department of Pharmacology and Experimental Therapeutics, The Whitaker Cardiovascular Institute, Boston University School of Medicine Boston, MA, USA
| | - Richard D Wainford
- The Department of Pharmacology and Experimental Therapeutics, The Whitaker Cardiovascular Institute, Boston University School of Medicine Boston, MA, USA
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66
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Oberleithner H, Wälte M, Kusche-Vihrog K. Sodium renders endothelial cells sticky for red blood cells. Front Physiol 2015; 6:188. [PMID: 26175691 PMCID: PMC4485165 DOI: 10.3389/fphys.2015.00188] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 06/16/2015] [Indexed: 02/05/2023] Open
Abstract
Negative charges in the glycocalyx of red blood cells (RBC) and vascular endothelial cells (EC) facilitate frictionless blood flow through blood vessels. Na+ selectively shields these charges controlling surface electronegativity. The question was addressed whether the ambient Na+ concentration controls RBC-EC interaction. Using atomic force microscopy (AFM) adhesion forces between RBC and endothelial glycocalyx were quantified. A single RBC, mounted on an AFM cantilever, was brought in physical contact with the endothelial surface and then pulled off. Adhesion forces were quantified (i) after enzymatic removal of negative charges in the glycocalyx, (ii) under different ambient Na+ and (iii) after applying the intracellular aldosterone receptor antagonist spironolactone. Removal of negative surface charges increases RBC-EC interaction forces. A stepwise increase of ambient Na+ from 133 to 140 mM does not affect them. However, beyond 140 mM Na+ adhesion forces increase sharply (10% increase of adhesion force per 1 mM increase of Na+). Spironolactone prevents this response. It is concluded that negative charges reduce adhesion between RBC and EC. Ambient Na+ concentration determines the availability of free negative charges. Na+ concentrations in the low physiological range (below 140 mM) allow sufficient amounts of vacant negative charges so that adhesion of RBC to the endothelial surface is small. In contrast, Na+ in the high physiological range (beyond 140 mM) saturates the remaining negative surface charges thus increasing adhesion. Aldosterone receptor blockade by spironolactone prevents Na+ induced RBC adhesion to the endothelial glycocalyx. Extrapolation of in vitro experiments to in vivo conditions leads to the hypothesis that high sodium intake is likely to increase the incidence of thrombotic events.
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Affiliation(s)
- Hans Oberleithner
- Medical Faculty, Institute of Physiology II, University of Münster Münster, Germany
| | - Mike Wälte
- Medical Faculty, Institute of Physiology II, University of Münster Münster, Germany
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67
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Dmitrieva NI, Burg MB. Elevated sodium and dehydration stimulate inflammatory signaling in endothelial cells and promote atherosclerosis. PLoS One 2015; 10:e0128870. [PMID: 26042828 PMCID: PMC4456159 DOI: 10.1371/journal.pone.0128870] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 05/03/2015] [Indexed: 12/22/2022] Open
Abstract
Cardiovascular diseases (CVDs) are a leading health problem worldwide. Epidemiologic studies link high salt intake and conditions predisposing to dehydration such as low water intake, diabetes and old age to increased risk of CVD. Previously, we demonstrated that elevation of extracellular sodium, which is a common consequence of these conditions, stimulates production by endothelial cells of clotting initiator, von Willebrand Factor, increases its level in blood and promotes thrombogenesis. In present study, by PCR array, using human umbilical vein endothelial cells (HUVECs), we analyzed the effect of high NaCl on 84 genes related to endothelial cell biology. The analysis showed that the affected genes regulate many aspects of endothelial cell biology including cell adhesion, proliferation, leukocyte and lymphocyte activation, coagulation, angiogenesis and inflammatory response. The genes whose expression increased the most were adhesion molecules VCAM1 and E-selectin and the chemoattractant MCP-1. These are key participants in the leukocyte adhesion and transmigration that play a major role in the inflammation and pathophysiology of CVD, including atherosclerosis. Indeed, high NaCl increased adhesion of mononuclear cells and their transmigration through HUVECs monolayers. In mice, mild water restriction that elevates serum sodium by 5 mmol/l, increased VCAM1, E-selectin and MCP-1 expression in mouse tissues, accelerated atherosclerotic plaque formation in aortic root and caused thickening or walls of coronary arteries. Multivariable linear regression analysis of clinical data from the Atherosclerosis Risk in Communities Study (n=12779) demonstrated that serum sodium is a significant predictor of 10 Years Risk of coronary heart disease. These findings indicate that elevation of extracellular sodium within the physiological range is accompanied by vascular changes that facilitate development of CVD. The findings bring attention to serum sodium as a risk factor for CVDs and give additional support to recommendations for dietary salt restriction and adequate water intake as preventives of CVD.
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Affiliation(s)
- Natalia I. Dmitrieva
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Maurice B. Burg
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
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68
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Associations between serum potassium and sodium levels and risk of hypertension: a community-based cohort study. JOURNAL OF GERIATRIC CARDIOLOGY : JGC 2015; 12:119-26. [PMID: 25870614 PMCID: PMC4394326 DOI: 10.11909/j.issn.1671-5411.2015.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 12/09/2014] [Accepted: 01/16/2015] [Indexed: 12/29/2022]
Abstract
Objective Several studies have examined the relationships between dietary potassium and sodium and hypertension, but few have evaluated the association between serum potassium or sodium and risk of incident hypertension. We therefore investigated the associations between serum potassium and sodium and risk of incident hypertension in a Chinese community-based population. Methods A total of 839 normotensive individuals without cardiovascular disease from the Chinese Multi-Provincial Cohort Study who took part in the baseline examination in 2007–2008 and the follow-up survey in 2012–2013 were included in this study. Odds ratios (OR) and 95% confidence intervals (95%CI) for baseline serum potassium and sodium in relation to the risk of new-onset hypertension were evaluated using multivariate logistic regression models. Results During five years of follow-up, 218 (26.0%) individuals progressed to hypertension. Logistic regression adjusting for multiple confounders showed that every 1 mEq/L increment in baseline serum potassium level was associated with a 75% increased risk of hypertension (OR: 1.75; 95%CI: 1.01–3.04; P = 0.04). Compared with adults with serum potassium level of 4.20–4.79 mEq/L, adults with level ≥ 4.80 mEq/L had an 84% increased risk of hypertension (OR: 1.84; 95%CI: 1.14–2.96; P = 0.01). There was no significant association between serum sodium and risk of hypertension (OR: 0.96; 95%CI: 0.89–1.04; P = 0.33). Conclusions Baseline serum potassium level, but not baseline serum sodium level, was positively related to the risk of incident hypertension in the Chinese population.
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69
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He FJ, MacGregor GA. Salt and sugar: their effects on blood pressure. Pflugers Arch 2014; 467:577-86. [PMID: 25547872 DOI: 10.1007/s00424-014-1677-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 12/08/2014] [Accepted: 12/15/2014] [Indexed: 01/09/2023]
Abstract
Both dietary salt and sugar are related to blood pressure (BP). The evidence for salt is much stronger, and various types of studies have consistently shown that salt is a major cause of raised BP, and a reduction from the current intake of ≈ 9-12 g/day in most countries of the world to the recommended level of 5-6 g/day lowers BP in both hypertensive and normotensive individuals, in men and women, in all age groups and in all ethnic groups. Countries such as Finland and the UK that have successfully reduced salt intake have demonstrated a reduction in population BP and cardiovascular mortality, with major cost savings to the health service. The mechanisms whereby salt raises BP are not fully understood. The traditional concepts focus on the tendency for an increase in extracellular fluid volume. Increasing evidence suggests that small increases in plasma sodium may play an important role. There are several other factors that also increase BP, one of which is added sugars. The current high intake of added sugars increases obesity which, in turn, raises BP. Recent studies also suggest that added sugars, particularly those in soft drinks, may have a direct effect on BP. However, the relationship between soft drink consumption and BP could be, at least partially, mediated by the effect of salt intake on increasing soft drink consumption. Actions to reduce salt and sugar intake across the whole population will have major beneficial effects on health along with major cost savings.
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Affiliation(s)
- Feng J He
- Wolfson Institute of Preventive Medicine, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK,
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70
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Orlov SN, Hamet P. Salt and gene expression: evidence for [Na+]i/[K+]i-mediated signaling pathways. Pflugers Arch 2014; 467:489-98. [PMID: 25479826 DOI: 10.1007/s00424-014-1650-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 10/27/2014] [Accepted: 11/07/2014] [Indexed: 01/11/2023]
Abstract
Our review focuses on the recent data showing that gene transcription and translation are under the control of signaling pathways triggered by modulation of the intracellular sodium/potassium ratio ([Na+]i/[K+]i). Side-by-side with sensing of osmolality elevation by tonicity enhancer-binding protein (TonEBP, NFAT5), [Na+]i/[K+]i-mediated excitation-transcription coupling may contribute to the transcriptomic changes evoked by high salt consumption. This novel mechanism includes the sensing of heightened Na+ concentration in the plasma, interstitial, and cerebrospinal fluids via augmented Na+ influx in the endothelium, immune system cells, and the subfornical organ, respectively. In these cells, [Na+]i/[K+]i ratio elevation, triggered by augmented Na+ influx, is further potentiated by increased production of endogenous Na+,K+-ATPase inhibitors documented in salt-sensitive hypertension.
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Affiliation(s)
- Sergei N Orlov
- Laboratory of Biological Membranes, Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1/12, Moscow, 119991, Russia,
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71
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Kusche-Vihrog K, Schmitz B, Brand E. Salt controls endothelial and vascular phenotype. Pflugers Arch 2014; 467:499-512. [DOI: 10.1007/s00424-014-1657-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/11/2014] [Accepted: 11/14/2014] [Indexed: 01/11/2023]
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van Gastel MDA, Meijer E, Scheven LE, Struck J, Bakker SJL, Gansevoort RT. Modifiable factors associated with copeptin concentration: a general population cohort. Am J Kidney Dis 2014; 65:719-27. [PMID: 25500109 DOI: 10.1053/j.ajkd.2014.10.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Accepted: 10/01/2014] [Indexed: 12/20/2022]
Abstract
BACKGROUND Vasopressin plays an important role in maintaining volume homeostasis. However, recent studies suggest that vasopressin also may play a detrimental role in the progression of chronic kidney disease. It therefore is of interest to identify factors that influence vasopressin concentration, particularly modifiable ones. STUDY DESIGN Cross-sectional analyses. SETTING & PARTICIPANTS Data used are from participants in a large general-population cohort study (Prevention of Renal and Vascular Endstage Disease [PREVEND]). Patients with a missing copeptin value (n=888), nonfasting blood sample (n=495), missing or assumed incorrect 24-hour urine collection (n=388), or heart failure (n=20) were excluded, leaving 6,801 participants for analysis. FACTOR Identification of lifestyle- and diet-related factors that are associated with copeptin concentration. OUTCOMES Copeptin concentration as surrogate for vasopressin. MEASUREMENTS Copeptin was measured by an immunoluminometric assay as a surrogate for vasopressin. Associations were assessed in uni- and multivariable linear regression analyses. RESULTS Median copeptin concentration was 4.7 (IQR, 2.9-7.6) pmol/L. When copeptin was studied as a dependent variable, the final stepwise backward model revealed associations with higher copeptin concentrations for lower 24-hour urine volume (P < 0.001), higher sodium excretion (P < 0.001), higher systolic blood pressure (P < 0.001), current smoking (P < 0.001), higher alcohol use (P < 0.001), higher urea excretion (P = 0.003), lower potassium excretion (P = 0.002), use of glucose-lowering drugs (P = 0.02), higher body mass index (P < 0.001), and higher plasma glucose level (P < 0.001). No associations with copeptin concentration were found for C-reactive protein or use of diuretics or nondiuretic antihypertensives. LIMITATIONS The cross-sectional study design does not allow firm conclusions on cause-effect relationships. CONCLUSIONS Important lifestyle- and diet-related factors associated with copeptin concentration are current smoking, alcohol use, protein and potassium intake, and particularly fluid and sodium intake. These data form a rationale to investigate whether intervening on these factors results in a lower vasopressin concentration with concomitant beneficial renal effects.
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Affiliation(s)
- Maatje D A van Gastel
- Department of Nephrology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Esther Meijer
- Department of Nephrology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Lieneke E Scheven
- Department of Nephrology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Joachim Struck
- ThermoFisher Scientific, Clinical Diagnostics, Hennigsdorf, Germany
| | - Stephan J L Bakker
- Department of Nephrology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Ron T Gansevoort
- Department of Nephrology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
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Stocker SD, Monahan KD, Browning KN. Neurogenic and sympathoexcitatory actions of NaCl in hypertension. Curr Hypertens Rep 2014; 15:538-46. [PMID: 24052211 DOI: 10.1007/s11906-013-0385-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Excess dietary salt intake is a major contributing factor to the pathogenesis of salt-sensitive hypertension. Strong evidence suggests that salt-sensitive hypertension is attributed to renal dysfunction, vascular abnormalities, and activation of the sympathetic nervous system. Indeed, sympathetic nerve transections or interruption of neurotransmission in various brain centers lowers arterial blood pressure (ABP) in many salt-sensitive models. The purpose of this article is to discuss recent evidence that supports a role of plasma or cerebrospinal fluid hypernatremia as a key mediator of sympathoexcitation and elevated ABP. Both experimental and clinical studies using time-controlled sampling have documented that a diet high in salt increases plasma and cerebrospinal fluid sodium concentration. To the extent it has been tested, acute and chronic elevations in sodium concentration activates the sympathetic nervous system in animals and humans. A further understanding of how the central nervous system detects changes in plasma or cerebrospinal fluid sodium concentration may lead to new therapeutic treatment strategies in salt-sensitive hypertension.
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Affiliation(s)
- Sean D Stocker
- Department of Cellular & Molecular Physiology, Pennsylvania State University College of Medicine, 500 University Drive H166, Hershey, PA, 17033, USA,
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74
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Dietary sodium, added salt, and serum sodium associations with growth and depression in the U.S. general population. Appetite 2014; 79:83-90. [DOI: 10.1016/j.appet.2014.04.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/02/2014] [Accepted: 04/09/2014] [Indexed: 01/31/2023]
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76
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Korte S, Sträter AS, Drüppel V, Oberleithner H, Jeggle P, Grossmann C, Fobker M, Nofer JR, Brand E, Kusche-Vihrog K. Feedforward activation of endothelial ENaC by high sodium. FASEB J 2014; 28:4015-25. [PMID: 24868010 DOI: 10.1096/fj.14-250282] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 05/19/2014] [Indexed: 01/11/2023]
Abstract
Kidney epithelial sodium channels (ENaCs) are known to be inactivated by high sodium concentrations (feedback inhibition). Recently, the endothelial sodium channel (EnNaC) was identified to control the nanomechanical properties of the endothelium. EnNaC-dependent endothelial stiffening reduces the release of nitric oxide, the hallmark of endothelial dysfunction. To study the regulatory impact of sodium on EnNaC, endothelial cells (EA.hy926 and ex vivo mouse endothelium) were incubated in aldosterone-free solutions containing either low (130 mM) or high (150 mM) sodium concentrations. By applying atomic force microscopy-based nanoindentation, an unexpected positive correlation between increasing sodium concentrations and cortical endothelial stiffness was observed, which can be attributed to functional EnNaC. In particular, an acute rise in sodium concentration (+20 mM) was sufficient to increase EnNaC membrane abundance by 90% and stiffening of the endothelial cortex by 18%. Despite the absence of exogenous aldosterone, these effects were prevented by the aldosterone synthase inhibitor FAD286 (100 nM) or the mineralocorticoid receptor (MR)-antagonist spironolactone (100 nM), indicating endogenous aldosterone synthesis and MR-dependent signaling. Interestingly, in the presence of high-sodium concentrations, FAD286 increased the transcription of the MR by 69%. Taken together, a novel feedforward activation of EnNaC by sodium is proposed that contrasts ENaC feedback inhibition in kidney.
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Affiliation(s)
- Stefanie Korte
- Institute of Physiology II, University of Münster, Münster, Germany
| | | | - Verena Drüppel
- Institute of Physiology II, University of Münster, Münster, Germany
| | | | - Pia Jeggle
- Institute of Physiology II, University of Münster, Münster, Germany
| | - Claudia Grossmann
- Julius-Bernstein-Institute of Physiology, University Halle-Wittenberg, Halle, Germany
| | - Manfred Fobker
- Center of Laboratory Medicine, University of Münster, Münster, Germany; and
| | - Jerzy-Roch Nofer
- Center of Laboratory Medicine, University of Münster, Münster, Germany; and
| | - Eva Brand
- Internal Medicine D, Department of Nephrology, Hypertension and Rheumatology, University Hospital Muenster, Muenster, Germany
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Secretion of von Willebrand factor by endothelial cells links sodium to hypercoagulability and thrombosis. Proc Natl Acad Sci U S A 2014; 111:6485-90. [PMID: 24733925 DOI: 10.1073/pnas.1404809111] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Hypercoagulability increases risk of thrombi that cause cardiovascular events. Here we identify plasma sodium concentration as a factor that modulates blood coagulability by affecting the production of von Willebrand factor (vWF), a key initiator of the clotting cascade. We find that elevation of salt over a range from the lower end of what is normal in blood to the level of severe hypernatremia reversibly increases vWF mRNA in endothelial cells in culture and the rate of vWF secretion from them. The high NaCl increases expression of tonicity-regulated transcription factor NFAT5 and its binding to promoter of vWF gene, suggesting involvement of hypertonic signaling in vWF up-regulation. To elevate NaCl in vivo, we modeled mild dehydration, subjecting mice to water restriction (WR) by feeding them with gel food containing 30% water. Such WR elevates blood sodium from 145.1 ± 0.5 to 150.2 ± 1.3 mmol/L and activates hypertonic signaling, evidenced from increased expression of NFAT5 in tissues. WR increases vWF mRNA in liver and lung and raises vWF protein in blood. Immunostaining of liver revealed increased production of vWF protein by endothelium and increased number of microthrombi inside capillaries. WR also increases blood level of D-dimer, indicative of ongoing coagulation and thrombolysis. Multivariate regression analysis of clinical data from the Atherosclerosis Risk in Communities Study demonstrated that serum sodium significantly contributes to prediction of plasma vWF and risk of stroke. The results indicate that elevation of extracellular sodium within the physiological range raises vWF sufficiently to increase coagulability and risk of thrombosis.
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78
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Sodium surfeit and potassium deficit: Keys to the pathogenesis of hypertension. ACTA ACUST UNITED AC 2014; 8:203-13. [DOI: 10.1016/j.jash.2013.09.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 09/20/2013] [Accepted: 09/22/2013] [Indexed: 12/26/2022]
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Warnock DG, Kusche-Vihrog K, Tarjus A, Sheng S, Oberleithner H, Kleyman TR, Jaisser F. Blood pressure and amiloride-sensitive sodium channels in vascular and renal cells. Nat Rev Nephrol 2014; 10:146-57. [PMID: 24419567 DOI: 10.1038/nrneph.2013.275] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Sodium transport in the distal nephron is mediated by epithelial sodium channel activity. Proteolytic processing of external domains and inhibition with increased sodium concentrations are important regulatory features of epithelial sodium channel complexes expressed in the distal nephron. By contrast, sodium channels expressed in the vascular system are activated by increased external sodium concentrations, which results in changes in the mechanical properties and function of endothelial cells. Mechanosensitivity and shear stress affect both epithelial and vascular sodium channel activity. Guyton's hypothesis stated that blood pressure control is critically dependent on vascular tone and fluid handling by the kidney. The synergistic effects, and complementary regulation, of the epithelial and vascular systems are consistent with the Guytonian model of volume and blood pressure regulation, and probably reflect sequential evolution of the two systems. The integration of vascular tone, renal perfusion and regulation of renal sodium reabsorption is the central underpinning of the Guytonian model. In this Review, we focus on the expression and regulation of sodium channels, and we outline the emerging evidence that describes the central role of amiloride-sensitive sodium channels in the efferent (vascular) and afferent (epithelial) arms of this homeostatic system.
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Affiliation(s)
- David G Warnock
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, 1720 2nd Avenue South, Birmingham, AL 34294-0007, USA
| | - Kristina Kusche-Vihrog
- Institut für Physiologie II, Westfälische Wilhelms Universität, Robert-Koch-Straße 27, 48149 Münster, Germany
| | - Antoine Tarjus
- INSERM U872 Team 1, Centre de Recherche des Cordeliers, Université René Descartes, Université Pierre et Marie Curie, 15 rue de l'Ecole de Médecine, 75006 Paris, France
| | - Shaohu Sheng
- Renal and Electrolyte Division, Department of Medicine, University of Pittsburgh, 3550 Terrace Street, Pittsburgh, PA 15261, USA
| | - Hans Oberleithner
- Institut für Physiologie II, Westfälische Wilhelms Universität, Robert-Koch-Straße 27, 48149 Münster, Germany
| | - Thomas R Kleyman
- Renal and Electrolyte Division, Department of Medicine, University of Pittsburgh, 3550 Terrace Street, Pittsburgh, PA 15261, USA
| | - Frederic Jaisser
- INSERM U872 Team 1, Centre de Recherche des Cordeliers, Université René Descartes, Université Pierre et Marie Curie, 15 rue de l'Ecole de Médecine, 75006 Paris, France
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Collister JP, Nahey DB, Hendel MD, Brooks VL. Roles of the subfornical organ and area postrema in arterial pressure increases induced by 48-h water deprivation in normal rats. Physiol Rep 2014; 2:e00191. [PMID: 24744870 PMCID: PMC3967674 DOI: 10.1002/phy2.191] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 11/26/2013] [Accepted: 11/27/2013] [Indexed: 12/19/2022] Open
Abstract
In rats, water deprivation (WD) increases arterial blood pressure (BP) in part due to actions of elevated osmolality in the brain to increase vasopressin levels and sympathetic activity. However, the osmoreceptors that mediate this response have not been identified. To test the hypothesis that osmoregulatory circumventricular organs are involved, BP and heart rate (HR) were continuously recorded telemetrically during 48 h of WD in normal rats with lesions (x) or sham lesions (sham) of the subfornical organ (SFO) or area postrema (AP). Although WD increased BP in SFOx and SFOsham rats, no significant difference in the hypertensive response was observed between groups. HR decreased transiently but similarly in SFOx and SFOsham rats during the first 24 h of WD. When water was reintroduced, BP and HR decreased rapidly and similarly in both groups. BP (during lights off) and HR were both lower in APx rats before WD compared to APsham. WD increased BP less in APx rats, and the transient bradycardia was eliminated. Upon reintroduction of drinking water, smaller falls in both BP and HR were observed in APx rats compared to APsham rats. WD increased plasma osmolality and vasopressin levels similarly in APx and APsham rats, and acute blockade of systemic V1 vasopressin receptors elicited similar depressor responses, suggesting that the attenuated BP response is not due to smaller increases in vasopressin or osmolality. In conclusion, the AP, but not the SFO, is required for the maximal hypertensive effect induced by WD in rats.
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Affiliation(s)
- John P Collister
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, 55108, Minnesota
| | - David B Nahey
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, 55108, Minnesota
| | - Michael D Hendel
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, 55108, Minnesota
| | - Virginia L Brooks
- Department of Physiology & Pharmacology, Oregon Health and Science University Portland, Oregon, 97239
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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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Essential hypertension: an approach to its etiology and neurogenic pathophysiology. Int J Hypertens 2013; 2013:547809. [PMID: 24386559 PMCID: PMC3872229 DOI: 10.1155/2013/547809] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Accepted: 11/06/2013] [Indexed: 12/24/2022] Open
Abstract
Essential hypertension, a rise in blood pressure of undetermined cause, includes 90% of all hypertensive cases and is a highly important public health challenge that remains, however, a major modifiable cause of morbidity and mortality. This review emphasizes that, from an evolutionary point of view, we are adapted to ingest and excrete <1 g of sodium (2.5 g of salt) per day and that essential hypertension develops when the kidneys become unable to excrete the amount of sodium ingested, unless blood pressure is increased. The renal-mean arterial pressure set-point model is briefly described to explain that a shift of the pressure natriuresis relationship toward abnormally high pressure levels is a pathophysiological characteristic of essential hypertension. Evidence indicating that this anomaly in the pressure natriuresis relationship arises from a sympathetic nervous system dysfunction is briefly formulated, and the most widely accepted pathophysiologic proposal to explain the development of this sympathetic dysfunction is described, with commentaries about novel action mechanisms of some drugs currently used in essential hypertension treatment.
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Abstract
In this review three major issues of sodium homeostasis are addressed. Specifically, volume-dependent (salt-sensitive) hypertension, sodium chloride content of maintenance fluid and clinical evaluation of hyponatremia are discussed. Regarding volume-dependent hypertension the endocrine/paracrine systems mediating renal sodium retention, the relationship between salt intake, plasma sodium levels and blood pressure, as well as data on the dissociation of sodium and volume regulation are presented. The concept of perinatal programming of salt-preference is also mentioned. Some theoretical and practical aspects of fluid therapy are summarized with particular reference to using hypotonic sodium chloride solution for maintenance fluid as opposed to the currently proposed isotonic sodium chloride solution. Furthermore, the incidence, the aetiological classification and central nervous system complications of hyponatremia are presented, too. In addition, clinical and pathophysical features of hyponatremic encephalophathy and osmotic demyelinisation are given. The adaptive reactions of the brain to hypotonic stress are also described with particular emphasis on the role of brain-specific water channel proteins (aquaporin-4) and the benzamil-inhibitable sodium channels. In view of the outmost clinical significance of hyponatremia, the principles of efficient and safe therapeutic approaches are outlined. Orv. Hetil., 2013, 154, 1488–1497.
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Affiliation(s)
- Endre Sulyok
- Pécsi Tudományegyetem Egészségtudományi Kar Pécs Vörösmarty u. 4. 7621
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84
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Oh SW, Baek SH, An JN, Goo HS, Kim S, Na KY, Chae DW, Kim S, Chin HJ. Small increases in plasma sodium are associated with higher risk of mortality in a healthy population. J Korean Med Sci 2013; 28:1034-40. [PMID: 23853486 PMCID: PMC3708074 DOI: 10.3346/jkms.2013.28.7.1034] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 05/10/2013] [Indexed: 01/20/2023] Open
Abstract
Elevated blood pressure (BP) is the most common cause of cardiovascular disease. Salt intake has a strong influence on BP, and plasma sodium (pNa) is increased with progressive increases in salt intake. However, the associations with pNa and BP had been reported inconsistently. We evaluated the association between pNa and BP, and estimated the risks of all-cause-mortality according to pNa levels. On the basis of data collected from health checkups during 1995-2009, 97,009 adult subjects were included. Positive correlations between pNa and systolic BP, diastolic BP, and pulse pressure (PP) were noted in participants with pNa ≥138 mM/L (P<0.001). In participants aged ≥50 yr, SBP, DBP, and PP were positively associated with pNa. In participants with metabolic syndrome components, the differences in SBP and DBP according to pNa were greater (P<0.001). A cumulative incidence of mortality was increased with increasing pNa in women aged ≥50 yr during the median 4.2-yr-follow-up (P<0.001). In women, unadjusted risks for mortality were increased according to sodium levels. After adjustment, pNa ≥145 mM/L was related to mortality. The positive correlation between pNa and BP is stronger in older subjects, women, and subjects with metabolic syndrome components. The incidence and adjusted risks of mortality increase with increasing pNa in women aged ≥50 yr.
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Affiliation(s)
- Se Won Oh
- Department of Internal Medicine, Eulji General Hospital, Eulji University College of Medicine, Seoul, Korea
| | - Seon Ha Baek
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Jung Nam An
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Ho Suk Goo
- Inje University Seoul Paik Hospital, Seoul, Korea
| | - Sejoong Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
| | - Ki Young Na
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
| | - Dong Wan Chae
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
| | - Suhnggwon Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
- Renal Institute, Seoul National University Medical Research Center, Seoul, Korea
| | - Ho Jun Chin
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
- Renal Institute, Seoul National University Medical Research Center, Seoul, Korea
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Abstract
PURPOSE OF REVIEW Endogenous cardiotonic steroids (CTS) exert long-term effects on salt and blood pressure homeostasis. Here we discuss recent observations on mechanisms of salt sensitivity that involve endogenous ouabain and novel pathways in the brain and discuss their possible relationship to arterial and renal function in hypertension. RECENT FINDINGS Chronic elevation of brain sodium promotes sustained hypertension mediated by central endogenous ouabain and the Na(+) pump α-2 catalytic subunit. The intermediary pressor mechanism in the brain involves aldosterone biosynthesis, activation of mineralocorticoid receptors and increased epithelial sodium channel activity. In the periphery, elevated plasma CTS raise contractility and blood pressure by augmentation of sympathetic nerve responses, increasing arterial Ca(2+) signaling and blunting nitric oxide production in the renal medulla and collecting ducts. SUMMARY Endogenous ouabain in the brain appears to play a critical role in salt sensitivity and hypertension. In the periphery, the J-shaped relationship of plasma endogenous ouabain in response to short-term changes in salt balance in humans raises the possibility that endogenous ouabain contributes to the increased risk of adverse cardiovascular events associated with both low and high salt intakes.
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86
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Abstract
BACKGROUND A reduction in salt intake lowers blood pressure (BP) and, thereby, reduces cardiovascular risk. A recent meta-analysis by Graudal implied that salt reduction had adverse effects on hormones and lipids which might mitigate any benefit that occurs with BP reduction. However, Graudal's meta-analysis included a large number of very short-term trials with a large change in salt intake, and such studies are irrelevant to the public health recommendations for a longer-term modest reduction in salt intake. We have updated our Cochrane meta-analysis. OBJECTIVES To assess (1) the effect of a longer-term modest reduction in salt intake (i.e. of public health relevance) on BP and whether there was a dose-response relationship; (2) the effect on BP by sex and ethnic group; (3) the effect on plasma renin activity, aldosterone, noradrenaline, adrenaline, cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglycerides. SEARCH METHODS We searched MEDLINE, EMBASE, Cochrane Hypertension Group Specialised Register, Cochrane Central Register of Controlled Trials, and reference list of relevant articles. SELECTION CRITERIA We included randomised trials with a modest reduction in salt intake and duration of at least 4 weeks. DATA COLLECTION AND ANALYSIS Data were extracted independently by two reviewers. Random effects meta-analyses, subgroup analyses and meta-regression were performed. MAIN RESULTS Thirty-four trials (3230 participants) were included. Meta-analysis showed that the mean change in urinary sodium (reduced salt vs usual salt) was -75 mmol/24-h (equivalent to a reduction of 4.4 g/d salt), the mean change in BP was -4.18 mmHg (95% CI: -5.18 to -3.18, I (2)=75%) for systolic and -2.06 mmHg (95% CI: -2.67 to -1.45, I (2)=68%) for diastolic BP. Meta-regression showed that age, ethnic group, BP status (hypertensive or normotensive) and the change in 24-h urinary sodium were all significantly associated with the fall in systolic BP, explaining 68% of the variance between studies. A 100 mmol reduction in 24 hour urinary sodium (6 g/day salt) was associated with a fall in systolic BP of 5.8 mmHg (95%CI: 2.5 to 9.2, P=0.001) after adjusting for age, ethnic group and BP status. For diastolic BP, age, ethnic group, BP status and the change in 24-h urinary sodium explained 41% of the variance between studies. Meta-analysis by subgroup showed that, in hypertensives, the mean effect was -5.39 mmHg (95% CI: -6.62 to -4.15, I (2)=61%) for systolic and -2.82 mmHg (95% CI: -3.54 to -2.11, I (2)=52%) for diastolic BP. In normotensives, the mean effect was -2.42 mmHg (95% CI: -3.56 to -1.29, I (2)=66%) for systolic and -1.00 mmHg (95% CI: -1.85 to -0.15, I (2)=66%) for diastolic BP. Further subgroup analysis showed that the decrease in systolic BP was significant in both whites and blacks, men and women. Meta-analysis of hormone and lipid data showed that the mean effect was 0.26 ng/ml/hr (95% CI: 0.17 to 0.36, I (2)=70%) for plasma renin activity, 73.20 pmol/l (95% CI: 44.92 to 101.48, I (2)=62%) for aldosterone, 31.67 pg/ml (95% CI: 6.57 to 56.77, I (2)=5%) for noradrenaline, 6.70 pg/ml (95% CI: -0.25 to 13.64, I (2)=12%) for adrenaline, 0.05 mmol/l (95% CI: -0.02 to 0.11, I (2)=0%) for cholesterol, 0.05 mmol/l (95% CI: -0.01 to 0.12, I (2)=0%) for LDL, -0.02 mmol/l (95% CI: -0.06 to 0.01, I (2)=16%) for HDL, and 0.04 mmol/l (95% CI: -0.02 to 0.09, I (2)=0%) for triglycerides. AUTHORS' CONCLUSIONS A modest reduction in salt intake for 4 or more weeks causes significant and, from a population viewpoint, important falls in BP in both hypertensive and normotensive individuals, irrespective of sex and ethnic group. With salt reduction, there is a small physiological increase in plasma renin activity, aldosterone and noradrenaline. There is no significant change in lipid levels. These results provide further strong support for a reduction in population salt intake. This will likely lower population BP and, thereby, reduce cardiovascular disease. Additionally, our analysis demonstrates a significant association between the reduction in 24-h urinary sodium and the fall in systolic BP, indicating the greater the reduction in salt intake, the greater the fall in systolic BP. The current recommendations to reduce salt intake from 9-12 to 5-6 g/d will have a major effect on BP, but are not ideal. A further reduction to 3 g/d will have a greater effect and should become the long term target for population salt intake.
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Affiliation(s)
- Feng J He
- Wolfson Institute of PreventiveMedicine, Barts and The London School of Medicine & Dentistry, QueenMary University of London, London, UK.
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87
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Mueller SM, Gehrig SM, Frese S, Wagner CA, Boutellier U, Toigo M. Multiday acute sodium bicarbonate intake improves endurance capacity and reduces acidosis in men. J Int Soc Sports Nutr 2013; 10:16. [PMID: 23531361 PMCID: PMC3623762 DOI: 10.1186/1550-2783-10-16] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 03/20/2013] [Indexed: 11/25/2022] Open
Abstract
Background The purpose was to investigate the effects of one dose of NaHCO3 per day for five consecutive days on cycling time-to-exhaustion (Tlim) at ‘Critical Power’ (CP) and acid–base parameters in endurance athletes. Methods Eight trained male cyclists and triathletes completed two exercise periods in a randomized, placebo-controlled, double-blind interventional crossover investigation. Before each period, CP was determined. Afterwards, participants completed five constant-load cycling trials at CP until volitional exhaustion on five consecutive days, either after a dose of NaHCO3 (0.3 g·kg-1 body mass) or placebo (0.045 g·kg-1 body mass NaCl). Results Average Tlim increased by 23.5% with NaHCO3 supplementation as compared to placebo (826.5 ± 180.1 vs. 669.0 ± 167.2 s; P = 0.001). However, there was no time effect for Tlim (P = 0.375). [HCO3-] showed a main effect for condition (NaHCO3: 32.5 ± 2.2 mmol·l-1; placebo: 26.2 ± 1.4 mmol·l-1; P < 0.001) but not for time (P = 0.835). NaHCO3 supplementation resulted in an expansion of plasma volume relative to placebo (P = 0.003). Conclusions The increase in Tlim was accompanied by an increase in [HCO3-], suggesting that acidosis might be a limiting factor for exercise at CP. Prolonged NaHCO3 supplementation did not lead to a further increase in [HCO3-] due to the concurrent elevation in plasma volume. This may explain why Tlim remained unaltered despite the prolonged NaHCO3 supplementation period. Ingestion of one single NaHCO3 dose per day before the competition during multiday competitions or tournaments might be a valuable strategy for performance enhancement. Trial registration Trial registration: ClinicalTrials.gov Identifier
NCT01621074
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Affiliation(s)
- Sandro Manuel Mueller
- Exercise Physiology, Institute of Human Movement Sciences, ETH Zurich, Zurich, Switzerland.
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88
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Yee-Moon Wang A, Lu Y, Cheung S, Hiu-Shuen Chan I, Wai-Kei Lam C. Plasma sodium and subclinical left atrial enlargement in chronic kidney disease. Nephrol Dial Transplant 2013; 28:2319-28. [PMID: 23314317 DOI: 10.1093/ndt/gfs588] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Left atrial enlargement (LAE) reflects diastolic dysfunction and predicts mortality in end-stage renal disease patients. However, little is known of its prevalence and factors associated with subclinical LAE in earlier stages of chronic kidney disease (CKD). METHODS We conducted a prospective, cross-sectional study in 261 Stage 3-5 non-dialysis CKD patients without symptomatic cardiovascular disease with two-dimensional echocardiography performed to estimate left atrial volume index and other cardiac parameters. RESULTS One hundred and nine (41.8%) patients had LAE. Mild and moderate/severe LAEs were observed in 22.9 and 41.3% of patients with left ventricular (LV) hypertrophy (n = 109) versus 13.2 and 12.5% of patients with no LV hypertrophy (n = 152), respectively (P < 0.001). On univariate analysis, plasma sodium concentration showed a significant association with LAE [odds ratio (OR) 1.22, 95% confidence interval (95% CI) 1.09-1.37; P = 0.001]. In the stepwise multiple logistic regression, plasma sodium concentration emerged as one of the most significant factors associated with LAE (adjusted OR 1.29, 95% CI 1.14-1.47; P < 0.001]. Its significance was well maintained (adjusted OR 1.23, 95% CI 1.07-1.43; P = 0.005) when including LV mass and volume index and N-terminal pro-brain natriuretic peptide in the model, while blood haemoglobin and systolic blood pressure were displaced. CONCLUSIONS This study for the first time alerted to a very high prevalence of subclinical LAE and reported a strong novel, independent relationship between plasma sodium concentration and subclinical LAE in Stage 3-5 CKD patients. Longitudinal studies are needed to establish causality between high plasma sodium concentration and LAE and their usefulness as therapeutic targets in CKD.
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89
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Kapusta DR, Pascale CL, Kuwabara JT, Wainford RD. Central nervous system Gαi2-subunit proteins maintain salt resistance via a renal nerve-dependent sympathoinhibitory pathway. Hypertension 2012; 61:368-75. [PMID: 23213191 DOI: 10.1161/hypertensionaha.111.00014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
In salt-resistant phenotypes, chronic elevated dietary sodium intake evokes suppression of renal sodium-retaining mechanisms to maintain sodium homeostasis and normotension. We have recently shown that brain Gαi(2) protein pathways are required to suppress renal sympathetic nerve activity and facilitate maximal sodium excretion during acute intravenous volume expansion in Sprague-Dawley rats. Here, we studied the role of brain Gαi(2) proteins in the endogenous central neural mechanisms acting to maintain fluid and electrolyte homeostasis and normotension during a chronic elevation in dietary salt intake. Naive or bilaterally renal denervated adult male Sprague-Dawley rats were randomly assigned to receive an intracerebroventricular scrambled or Gαi(2) oligodeoxynucleotide infusion and then subjected to either a normal salt (0.4%) or high-salt (8.0%) diet for 21 days. In scrambled oligodeoxynucleotide-infused rats, salt loading, which did not alter blood pressure, evoked a site-specific increase in hypothalamic paraventricular nucleus Gαi(2) protein levels and suppression of circulating norepinephrine content and plasma renin activity. In salt-loaded rats continuously infused intracerebroventricularly with a Gαi(2) oligodeoxynucleotide, animals exhibited sodium and water retention, elevated plasma norepinephrine levels, and hypertension, despite suppression of plasma renin activity. Furthermore, in salt-loaded bilaterally renal denervated rats, Gαi(2) oligodeoxynucleotide infusion failed to evoke salt-sensitive hypertension. Therefore, in salt-resistant rats subjected to a chronic high-salt diet, brain Gαi(2) proteins are required to inhibit central sympathetic outflow to the kidneys and maintain sodium balance and normotension. In conclusion, these data demonstrate a central role of endogenous brain, likely paraventricular nucleus-specific, Gαi(2)-subunit protein-gated signal transduction pathways in maintaining a salt-resistant phenotype.
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Affiliation(s)
- Daniel R Kapusta
- Department of Pharmacology and Experimental Therapeutics and the Whitaker Cardiovascular Institute, Boston University School of Medicine, 72 E Concord St, Boston, MA 02118, USA
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90
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Hallersund P, Sjöström L, Olbers T, Lönroth H, Jacobson P, Wallenius V, Näslund I, Carlsson LM, Fändriks L. Gastric bypass surgery is followed by lowered blood pressure and increased diuresis - long term results from the Swedish Obese Subjects (SOS) study. PLoS One 2012; 7:e49696. [PMID: 23209592 PMCID: PMC3510228 DOI: 10.1371/journal.pone.0049696] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Accepted: 10/15/2012] [Indexed: 01/14/2023] Open
Abstract
Objective To compare two bariatric surgical principles with regard to effects on blood pressure and salt intake. Background In most patients bariatric surgery induces a sustained weight loss and a reduced cardiovascular risk profile but the long-term effect on blood pressure is uncertain. Methods Cohort study with data from the prospective, controlled Swedish Obese Subjects (SOS) study involving 480 primary health care centres and 25 surgical departments in Sweden. Obese patients treated with non-surgical methods (Controls, n = 1636 and n = 1132 at 2 y and 10 y follow up, respectively) were compared to patients treated with gastric bypass (GBP, n = 245 and n = 277, respectively) or purely restrictive procedures (vertical banded gastroplasty or gastric banding; VBG/B, n = 1534 and n = 1064, respectively). Results At long-term follow-up (median 10 y) GBP was associated with lowered systolic (mean: −5.1 mm Hg) and diastolic pressure (−5.6 mmHg) differing significantly from both VBG/B (−1.5 and −2.1 mmHg, respectively; p<0.001) and Controls (+1.2 and −3.8 mmHg, respectively; p<0.01). Diurnal urinary output was +100 ml (P<0.05) and +170 ml (P<0.001) higher in GBP subjects than in weight-loss matched VBG/B subjects at the 2 y and 10 y follow-ups, respectively. Urinary output was linearly associated with blood pressure only after GBP and these patients consumed approximately 1 g salt per day more at the follow-ups than did VBG/B (P<0.01). Conclusions The purely restrictive techniques VBG/B exerted a transient blood pressure lowering effect, whereas gastric bypass was associated with a sustained blood pressure reduction and an increased diuresis. The daily salt consumption was higher after gastric bypass than after restrictive bariatric surgery.
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Affiliation(s)
- Peter Hallersund
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lars Sjöström
- Department of Molecular and Clinical Medicine and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Torsten Olbers
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Hans Lönroth
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Peter Jacobson
- Department of Molecular and Clinical Medicine and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ville Wallenius
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ingmar Näslund
- Department of Molecular and Clinical Medicine and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lena M. Carlsson
- Department of Molecular and Clinical Medicine and Center for Cardiovascular and Metabolic Research, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lars Fändriks
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- * E-mail:
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91
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Kusche-Vihrog K, Oberleithner H. An emerging concept of vascular salt sensitivity. F1000 BIOLOGY REPORTS 2012; 4:20. [PMID: 23112808 PMCID: PMC3463896 DOI: 10.3410/b4-20] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Excessive amounts of salt in food, as usually consumed worldwide, affect the vascular system, leading to high blood pressure and premature disabilities. Salt entering the vascular bed after a salty meal is transiently bound to the endothelial glycocalyx, a negatively charged biopolymer lining the inner surface of the blood vessels. This barrier protects the endothelium against salt overload. A poorly-developed glycocalyx increases the salt permeability of the vascular system and the amount of salt being deposited in the body, which affects organ function. A simple test system is now available that evaluates vascular salt sensitivity in humans and identifies individuals who are at risk of salt-induced hypertension. This short review aims to discuss how the underlying basic research can be translated into medical practice and, thus, meaningful health outcomes.
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Affiliation(s)
- Kristina Kusche-Vihrog
- Institute of Physiology II, Medical Faculty, University of Münster Robert-Koch-Strasse 27, 48149 Münster Germany
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92
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Abstract
There is overwhelming evidence that a reduction in salt intake from the current level of approximately 9-12 g/d in most countries of the world to the recommended level of 5-6 g/d lowers blood pressure (BP) in both hypertensive and normotensive individuals. A further reduction to 3-4 g/d has a greater effect. Prospective studies and outcome trials have demonstrated that a lower salt intake is related to a reduced risk of cardiovascular disease. Cost-effectiveness analyses have documented that salt reduction is more or at the very least just as cost-effective as tobacco control in reducing cardiovascular disease, the leading cause of death and disability worldwide. The mechanisms whereby salt raises blood pressure and increases cardiovascular risk are not fully understood. The existing concepts focus on the tendency for an increase in extracellular fluid volume. Increasing evidence suggests that small increases in plasma sodium may have a direct effect on BP and the cardiovascular system, independent of extracellular volume. All countries should adopt a coherent and workable strategy to reduce salt intake in the whole population. Even a modest reduction in population salt intake will have major beneficial effects on health, along with major cost savings.
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Affiliation(s)
- Feng J He
- Wolfson Institute of Preventive Medicine, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, UK.
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93
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Abstract
Vascular endothelium plays a key role in blood pressure regulation. Recently, it has been shown that a 5% increase of plasma sodium concentration (sodium excess) stiffens endothelial cells by about 25%, leading to cellular dysfunction. Surface measurements demonstrated that the endothelial glycocalyx (eGC), an anionic biopolymer, deteriorates when sodium is elevated. In view of these results, a two-barrier model for sodium exiting the circulation across the endothelium is suggested. The first sodium barrier is the eGC which selectively buffers sodium ions with its negatively charged proteoglycans. The second sodium barrier is the endothelial plasma membrane which contains sodium channels. Sodium excess, in the presence of aldosterone, leads to eGC break-down and, in parallel, to an up-regulation of plasma membrane sodium channels. The following hypothesis is postulated: Sodium excess increases vascular sodium permeability. Under such conditions (e.g. high-sodium diet), day-by-day ingested sodium, instead of being readily buffered by the eGC and then rapidly excreted by the kidneys, is distributed in the whole body before being finally excreted. Gradually, the sodium overload damages the organism.
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Affiliation(s)
- Hans Oberleithner
- Institute of Physiology II, University of Münster, Münster, Germany.
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94
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Kapusta DR, Pascale CL, Wainford RD. Brain heterotrimeric Gαi₂-subunit protein-gated pathways mediate central sympathoinhibition to maintain fluid and electrolyte homeostasis during stress. FASEB J 2012; 26:2776-87. [PMID: 22459149 DOI: 10.1096/fj.11-196550] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Fluid and electrolyte homeostasis is integral to blood pressure regulation. However, the central molecular mechanisms regulating the neural control of sodium excretion remain unclear. We have demonstrated that brain Gαi(2)-subunit protein pathways mediate the natriuretic response to α(2)-adrenoreceptor activation in vivo. Consequently, we examined the role of brain Gαi(2) proteins in the neural mechanisms facilitating fluid and electrolyte homeostasis in response to acute [i.v. volume expansion (VE)] or chronic stressful stimuli (dietary sodium restriction vs. supplementation) in conscious Sprague-Dawley rats. Selective oligodeoxynucleotide (ODN)-mediated down-regulation of brain Gαi(2) proteins, but not a scrambled ODN, abolished the renal sympathoinhibitory response and attenuated the natriuresis to VE. In scrambled ODN-treated rats, chronic changes in dietary sodium intake evoked an endogenous, hypothalamic paraventricular nucleus (PVN)-specific, decrease (sodium deficiency) or increase (sodium excess) in PVN Gαi(2) proteins; plasma norepinephrine levels were inversely related to dietary sodium content. Finally, in rats treated with an ODN to prevent high salt-induced up-regulation of brain Gαi(2) proteins, animals exhibited sodium retention, global sympathoexcitation, and elevated blood pressure. Collectively, these data demonstrate that PVN Gαi(2) protein pathways play an endogenous role in maintaining fluid and electrolyte balance by controlling the influence the sympathetic nervous system has on the renal handling of sodium.
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Affiliation(s)
- Daniel R Kapusta
- Department of Pharmacology and Experimental Therapeutics and Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
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95
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96
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Acute arrhythmogenesis after myocardial infarction in normotensive rats: Influence of high salt intake. Food Chem Toxicol 2012; 50:473-7. [DOI: 10.1016/j.fct.2011.11.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 11/18/2011] [Accepted: 11/19/2011] [Indexed: 12/22/2022]
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97
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Wenner MM, Edwards DG, Ray CA, Rose WC, Gardner TJ, Stillabower M, Farquhar WB. Celecoxib does not alter cardiovascular and renal function during dietary salt loading. Clin Exp Pharmacol Physiol 2012; 38:543-9. [PMID: 21631568 DOI: 10.1111/j.1440-1681.2011.05546.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. Cyclo-oxygenase-2 (COX-2)-derived prostaglandins are important in controlling sodium excretion and renin release. In the present study, we tested the hypothesis that a clinical dose of celecoxib would impair urinary sodium excretion and elevate blood pressure (BP) during dietary salt loading. 2. Twelve normotensive individuals (mean (± SEM) age 35 ± 2 years) completed two separate 17 day dietary perturbations, one taking 200 mg/day celecoxib (CX2) and the other taking placebo (PL), randomized with a 1 month wash out. The controlled 17 day diet consisted of a 3 day run-in diet, 7 days of a low-salt (LS, 20 mmol sodium/day) diet and 7 days of a high-salt diet (HS, 350 mmol sodium/day) diet. The order in which the diets were applied was randomized. Data were collected on the last day of the LS and HS diets. 3. Plasma and urinary prostaglandins were modestly lower during celecoxib (P < 0.05). Urinary sodium excretion was greater (P < 0.01) during the HS diet (253 ± 10 vs 281 ± 27 mmol/24 h for PL vs CX2, respectively) compared with the LS diet (14 ± 3 vs 17 ± 7 mmol/24 h for PL vs CX2, respectively; P(drug) = 0.26). Celecoxib did not alter creatinine clearance (P > 0.50). Twenty-four hour mean arterial BP was similar during PL (87 ± 2 vs 87 ± 2 mmHg for LS and HS, respectively) and CX2 (88 ± 2 vs 87 ± 2 mmHg for LS and HS, respectively; P = 0.85), with no effect of dietary salt (P > 0.80). Plasma renin activity, angiotensin II and aldosterone were all suppressed with dietary salt loading (P < 0.05), with no effect of drug (P > 0.35). 4. In conclusion, blood pressure and renal function were not adversely affected by celecoxib, even during dietary salt loading. These findings support current guidelines suggesting minimal cardiovascular risks associated with short-term, low-dose use of celecoxib in young to middle-aged adults.
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Affiliation(s)
- Megan M Wenner
- Department of Kinesiology and Applied Physiology, University of Delaware, USA
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98
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Lee H, Oh SW, Heo NJ, Chin HJ, Na KY, Kim S, Chae DW. Serum phosphorus as a predictor of low-grade albuminuria in a general population without evidence of chronic kidney disease. Nephrol Dial Transplant 2012; 27:2799-806. [PMID: 22262737 DOI: 10.1093/ndt/gfr762] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND High levels of serum phosphorus, even within the normal range, have been associated with cardiovascular (CV) morbidity. Low-grade albuminuria (LGA) was demonstrated to be related to increased CV events in various study populations. The present study aimed to investigate the association between serum phosphorus levels and LGA in the general population. METHODS We examined the individuals who had undergone health inspections. We evaluated the correlation between serum phosphorus and LGA in 8953 participants (mean age, 47.4 years) with estimated glomerular filtration rates (eGFRs)≥60 mL/min/1.73 m2 and urinary albumin-to-creatinine ratios (UACRs)<30 mg/g. Participants who underwent a colonoscopy were excluded. RESULTS The mean UACR was significantly higher in the uppermost quartile group of serum phosphorus concentrations than in other quartile groups. In the multivariate regression analysis, serum phosphorus remained an independent predictor of increased UACR (B=0.610, P<0.001). Subgroup analyses showed that this association was maintained irrespective of age, gender, presence of hypertension or diabetes, body mass index and eGFR. CONCLUSIONS In our population-based study, higher serum phosphorus was independently related to LGA in individuals without evidence of renal dysfunction. Further investigations are warranted to clarify the precise mechanism of the association between serum phosphorus and LGA.
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Affiliation(s)
- Hajeong Lee
- Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
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99
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Korte S, Wiesinger A, Straeter AS, Peters W, Oberleithner H, Kusche-Vihrog K. Firewall function of the endothelial glycocalyx in the regulation of sodium homeostasis. Pflugers Arch 2011; 463:269-78. [PMID: 22057584 DOI: 10.1007/s00424-011-1038-y] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 09/30/2011] [Accepted: 10/03/2011] [Indexed: 12/15/2022]
Abstract
Plasma sodium, slightly above normal and in presence of aldosterone, stiffens vascular endothelium and reduces nitric oxide release with the consequence of endothelial dysfunction. This process is mediated by epithelial sodium channels (ENaC) and, most likely, the endothelial Na(+)/K(+)-ATPase. Both, ENaC and Na(+)/K(+)-ATPase, are located in the plasma membrane of endothelial cells and embedded in the endothelial glycocalyx (eGC). This negatively charged biopolymer is directly exposed to the blood stream and selectively buffers sodium ions. We hypothesize that the glycocalyx could interfere with endothelial sodium transport when extracellular sodium varies in the physiological range. Therefore, we modeled the endothelial cell as a pump-leak system measuring changes of intracellular sodium in cultured human endothelial cells. Experiments were performed under low/high extracellular sodium conditions before and after enzymatic eGC removal, and with inhibition of Na(+)/K(+)-ATPase and ENaC, respectively. Three major observations were made: (1) eGC removal by heparinase treatment facilitates sodium to enter/exit the endothelial cells. (2) The direction of net sodium movement across the endothelial plasma membrane depends on the concentration of extracellular sodium which regulates both the Na(+)/K(+)-ATPase and ENaC activity. (3) Removal of eGC and inhibition of sodium transport modify the electrical resistance of endothelial cells. We conclude that the eGC serves as a potential "firewall" preventing uncontrolled access of sodium to the pump-leak system of the endothelial cell. After eGC removal, sodium access to the system is facilitated. Thus the pump-leak system could be regulated by ambient sodium and control vascular permeability in pathophysiological conditions.
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Affiliation(s)
- Stefanie Korte
- Institute of Physiology II, University of Muenster, Robert-Koch-Strasse 27 b, 48149, Münster, Germany
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100
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Blaustein MP, Leenen FHH, Chen L, Golovina VA, Hamlyn JM, Pallone TL, Van Huysse JW, Zhang J, Wier WG. How NaCl raises blood pressure: a new paradigm for the pathogenesis of salt-dependent hypertension. Am J Physiol Heart Circ Physiol 2011; 302:H1031-49. [PMID: 22058154 DOI: 10.1152/ajpheart.00899.2011] [Citation(s) in RCA: 175] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Excess dietary salt is a major cause of hypertension. Nevertheless, the specific mechanisms by which salt increases arterial constriction and peripheral vascular resistance, and thereby raises blood pressure (BP), are poorly understood. Here we summarize recent evidence that defines specific molecular links between Na(+) and the elevated vascular resistance that directly produces high BP. In this new paradigm, high dietary salt raises cerebrospinal fluid [Na(+)]. This leads, via the Na(+)-sensing circumventricular organs of the brain, to increased sympathetic nerve activity (SNA), a major trigger of vasoconstriction. Plasma levels of endogenous ouabain (EO), the Na(+) pump ligand, also become elevated. Remarkably, high cerebrospinal fluid [Na(+)]-evoked, locally secreted (hypothalamic) EO participates in a pathway that mediates the sustained increase in SNA. This hypothalamic signaling chain includes aldosterone, epithelial Na(+) channels, EO, ouabain-sensitive α(2) Na(+) pumps, and angiotensin II (ANG II). The EO increases (e.g.) hypothalamic ANG-II type-1 receptor and NADPH oxidase and decreases neuronal nitric oxide synthase protein expression. The aldosterone-epithelial Na(+) channel-EO-α(2) Na(+) pump-ANG-II pathway modulates the activity of brain cardiovascular control centers that regulate the BP set point and induce sustained changes in SNA. In the periphery, the EO secreted by the adrenal cortex directly enhances vasoconstriction via an EO-α(2) Na(+) pump-Na(+)/Ca(2+) exchanger-Ca(2+) signaling pathway. Circulating EO also activates an EO-α(2) Na(+) pump-Src kinase signaling cascade. This increases the expression of the Na(+)/Ca(2+) exchanger-transient receptor potential cation channel Ca(2+) signaling pathway in arterial smooth muscle but decreases the expression of endothelial vasodilator mechanisms. Additionally, EO is a growth factor and may directly participate in the arterial structural remodeling and lumen narrowing that is frequently observed in established hypertension. These several central and peripheral mechanisms are coordinated, in part by EO, to effect and maintain the salt-induced elevation of BP.
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Affiliation(s)
- Mordecai P Blaustein
- Dept. of Physiology, Univ. of Maryland School of Medicine, 655 W. Baltimore St., Baltimore, MD, 21201, USA.
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