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Zhang J, Yuan HK, Chen S, Zhang ZR. Detrimental or beneficial: Role of endothelial ENaC in vascular function. J Cell Physiol 2021; 237:29-48. [PMID: 34279047 DOI: 10.1002/jcp.30505] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 06/29/2021] [Accepted: 07/01/2021] [Indexed: 12/19/2022]
Abstract
In the past, it was believed that the expression of the epithelial sodium channel (ENaC) was restricted to epithelial tissues, such as the distal nephron, airway, sweat glands, and colon, where it is critical for sodium homeostasis. Over the past two decades, this paradigm has shifted due to the finding that ENaC is also expressed in various nonepithelial tissues, notably in vascular endothelial cells. In this review, the recent findings of the expression, regulation, and function of the endothelial ENaC (EnNaC) are discussed. The expression of EnNaC subunits is reported in a variety of endothelial cell lines and vasculatures, but this is controversial across different species and vessels and is not a universal finding in all vascular beds. The expression density of EnNaC is very faint compared to ENaC in the epithelium. To date, little is known about the regulatory mechanism of EnNaC. Through it can be regulated by aldosterone, the detailed downstream signaling remains elusive. EnNaC responds to increased extracellular sodium with the feedforward activation mechanism, which is quite different from the Na+ self-inhibition mechanism of ENaC. Functionally, EnNaC was shown to be a determinant of cellular mechanics and vascular tone as it can sense shear stress, and its activation or insertion into plasma membrane causes endothelial stiffness and reduced nitric oxide production. However, in some blood vessels, EnNaC is essential for maintaining the integrity of endothelial barrier function. In this context, we discuss the possible reasons for the distinct role of EnNaC in vasculatures.
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Affiliation(s)
- Jun Zhang
- School of Biomedical Sciences and Li Ka Shing Institute of Health Science, The Chinese University of Hong Kong, Hong Kong, China
| | - Hui-Kai Yuan
- Department of General Surgery, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Shuo Chen
- Department of Biopharmaceutical Sciences, School of Pharmacy, Harbin Medical University (Daqing), Daqing, China
| | - Zhi-Ren Zhang
- Departments of Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang Key Laboratory for Metabolic Disorder & Cancer Related Cardiovascular Diseases, NHC Key Laboratory of Cell Transplantation, Harbin Medical University & Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
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Hill MA, Yang Y, Zhang L, Sun Z, Jia G, Parrish AR, Sowers JR. Insulin resistance, cardiovascular stiffening and cardiovascular disease. Metabolism 2021; 119:154766. [PMID: 33766485 DOI: 10.1016/j.metabol.2021.154766] [Citation(s) in RCA: 194] [Impact Index Per Article: 64.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 03/10/2021] [Accepted: 03/17/2021] [Indexed: 12/18/2022]
Abstract
The cardiometabolic syndrome (CMS) and obesity are typically characterized by a state of metabolic insulin resistance. As global and US rates of obesity increase there is an acceleration of the incidence and prevalence of insulin resistance along with associated cardiovascular disease (CVD). Under physiological conditions insulin regulates glucose homeostasis by enhancing glucose disposal in insulin sensitive tissues while also regulating delivery of nutrients through its vasodilation actions on small feed arteries. Specifically, insulin-mediated production of nitric oxide (NO) from the vascular endothelium leads to increased blood flow enhancing disposal of glucose. Typically, insulin resistance is considered as a decrease in sensitivity or responsiveness to the metabolic actions of insulin including insulin-mediated glucose disposal. However, a decreased sensitivity to the normal vascular actions of insulin, especially diminished nitric oxide production, plays an additional important role in the development of CVD in states of insulin resistance. One mechanism by which insulin resistance and attendant hyperinsulinemia promote CVD is via increases in vascular stiffness. Although obesity and insulin resistance are known to be associated with substantial increases in the prevalence of vascular fibrosis and stiffness the mechanisms and mediators that underlie vascular stiffening in insulin resistant states are complex and have only recently begun to be addressed. Current evidence supports the role of increased plasma levels of aldosterone and insulin and attendant reductions in bioavailable NO in the pathogenesis of impaired vascular relaxation and vascular stiffness in the CMS and obesity. Aldosterone and insulin both increase the activity of serum and glucocorticoid kinase 1 (SGK-1) which in turn is a major regulator of vascular and renal sodium (Na+) channel activity.The importance of SGK-1 in the pathogenesis of the CMS is highlighted by observations that gain of function mutations in SGK-1 in humans promotes hypertension, insulin resistance and obesity. In endothelial cells, an increase in Na+ flux contributes to remodeling of the cytoskeleton, reduced NO bioavailability and vascular stiffening. Thus, endothelial SGK-1 may represent a point of convergence for insulin and aldosterone signaling in arterial stiffness associated with obesity and the CMS. This review examines our contemporary understanding of the link between insulin resistance and increased vascular stiffness with emphasis placed on a role for enhanced SGK-1 signaling as a key node in this pathological process.
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Affiliation(s)
- Michael A Hill
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, USA; Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO 65212, USA.
| | - Yan Yang
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, USA
| | - Liping Zhang
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, USA; Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO 65212, USA
| | - Zhe Sun
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, USA; Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO 65212, USA
| | - Guanghong Jia
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, USA; Diabetes and Cardiovascular Center, University of Missouri School of Medicine, Columbia, MO 65212, USA; Department of Medicine, University of Missouri School of Medicine, Columbia, MO 65212, USA
| | - Alan R Parrish
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO 65212, USA
| | - James R Sowers
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, USA; Diabetes and Cardiovascular Center, University of Missouri School of Medicine, Columbia, MO 65212, USA; Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO 65212, USA; Department of Medicine, University of Missouri School of Medicine, Columbia, MO 65212, USA.
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Ydegaard R, Andersen H, Oxlund CS, Jacobsen IA, Hansen PBL, Jürgensen JF, Peluso AA, Vanhoutte PM, Staehr M, Svenningsen P, Jensen BL. The acute blood pressure-lowering effect of amiloride is independent of endothelial ENaC and eNOS in humans and mice. Acta Physiol (Oxf) 2019; 225:e13189. [PMID: 30240139 DOI: 10.1111/apha.13189] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 09/11/2018] [Accepted: 09/17/2018] [Indexed: 01/15/2023]
Abstract
AIMS The epithelial sodium channel (ENaC) is expressed in cultured endothelial cells and inhibitory coupling to eNOS activity has been proposed. The present study tested the hypothesis that ENaC blockers increase systemic NO-products and lower blood pressure in patients and mice, depending on eNOS. METHODS NO-products and cGMP were measured in diabetes patient urine and plasma samples before and after amiloride treatment (20-40 mg for two days, plasma n = 22, urine n = 12 and 5-10 mg for eight weeks, plasma n = 52, urine n = 55). Indwelling catheters were implanted in the femoral artery and vein in mice for continuous arterial blood pressure and heart rate recordings and infusion. RESULTS Treatment with amiloride for two days increased plasma and urine NO-products, while plasma cGMP decreased and urinary cGMP was unchanged in patient samples. Eight weeks of treatment with amiloride did not alter NO-products and cGMP. In mice, amiloride boli of 5, 50, and 500 µg/kg lowered heart rate and arterial blood pressure significantly and acutely. Benzamil had no effect on pressure and raised heart rate. In hypertensive eNOS-/- and L-NAME-treated mice, amiloride lowered blood pressure significantly. L-NAME infusion significantly decreased NO-products in plasma; amiloride and eNOS-deletion had no effect. An acetylcholine bolus resulted in acute blood pressure drop that was attenuated in eNOS-/- and L-NAME mice. ENaC subunit expressions were not detected consistently in human and mouse arteries and endothelial cells. CONCLUSION Amiloride has an acute hypotensive action not dependent on ENaC and eNOS and likely related to the heart.
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Affiliation(s)
- Rikke Ydegaard
- Department of Cardiovascular and Renal Research, Institute for Molecular Medicine; University of Southern Denmark; Odense C Denmark
| | - Henrik Andersen
- Department of Cardiovascular and Renal Research, Institute for Molecular Medicine; University of Southern Denmark; Odense C Denmark
| | | | - Ib A. Jacobsen
- Department of Endocrinology; Odense University Hospital; Odense Denmark
| | - Pernille B. L. Hansen
- Department of Cardiovascular and Renal Research, Institute for Molecular Medicine; University of Southern Denmark; Odense C Denmark
- Cardiovascular and Metabolic Disease, IMED Biotech Unit; AstraZeneca; Gothenburg Sweden
| | - Jonathan F. Jürgensen
- Department of Cardiovascular and Renal Research, Institute for Molecular Medicine; University of Southern Denmark; Odense C Denmark
| | - Antonio Augusto Peluso
- Department of Cardiovascular and Renal Research, Institute for Molecular Medicine; University of Southern Denmark; Odense C Denmark
| | - Paul M. Vanhoutte
- Department of Pharmacology and Pharmacy; Hong Kong University; China
| | - Mette Staehr
- Department of Cardiovascular and Renal Research, Institute for Molecular Medicine; University of Southern Denmark; Odense C Denmark
| | - Per Svenningsen
- Department of Cardiovascular and Renal Research, Institute for Molecular Medicine; University of Southern Denmark; Odense C Denmark
| | - Boye L. Jensen
- Department of Cardiovascular and Renal Research, Institute for Molecular Medicine; University of Southern Denmark; Odense C Denmark
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Olde Engberink RHG, Rorije NMG, Homan van der Heide JJ, van den Born BJH, Vogt L. Role of the vascular wall in sodium homeostasis and salt sensitivity. J Am Soc Nephrol 2014; 26:777-83. [PMID: 25294232 DOI: 10.1681/asn.2014050430] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Excessive sodium intake is associated with both hypertension and an increased risk of cardiovascular events, presumably because of an increase in extracellular volume. The extent to which sodium intake affects extracellular volume and BP varies considerably among individuals, discriminating subjects who are salt-sensitive from those who are salt-resistant. Recent experiments have shown that, other than regulation by the kidney, sodium homeostasis is also regulated by negatively charged glycosaminoglycans in the skin interstitium, where sodium is bound to glycosaminoglycans without commensurate effects on extracellular volume. The endothelial surface layer is a dynamic layer on the luminal side of the endothelium that is in continuous exchange with flowing blood. Because negatively charged glycosaminoglycans are abundantly present in this layer, it may act as an intravascular buffer compartment that allows sodium to be transiently stored. This review focuses on the putative role of the endothelial surface layer as a contributor to salt sensitivity, the consequences of a perturbed endothelial surface layer on sodium homeostasis, and the endothelial surface layer as a possible target for the treatment of hypertension and an expanded extracellular volume.
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Affiliation(s)
| | | | | | - Bert-Jan H van den Born
- Department of Internal Medicine, Vascular Medicine, Academic Medical Centre, University of Amsterdam, The Netherlands
| | - Liffert Vogt
- Department of Internal Medicine, Divisions of Nephrology, and
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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