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Chen X, Wu H, Huang S. Excessive Sodium Intake Leads to Cardiovascular Disease by Promoting Sex-Specific Dysfunction of Murine Heart. Front Nutr 2022; 9:830738. [PMID: 35845798 PMCID: PMC9285006 DOI: 10.3389/fnut.2022.830738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 05/16/2022] [Indexed: 11/17/2022] Open
Abstract
Background Globally, a high-salt diet (HSD) has become a threat to human health as it can lead to a high risk of cardiac damage. Although some studies investigating HSD have been carried out, the majority has been conducted in males, and there are few female-specific studies, thereby ignoring any effects of sex-specific damage on the heart. In this study, we determined how HSD induces different pathways of cardiovascular diseases through sex-specific effects on cardiac damage in mice. Methods An HSD murine model of male and female C57BL/6J mice was fed with sodium-rich chow (4% NaCl). After 8 weeks, cardiac tissues were collected, and the whole gene transcriptome of the hearts of male and female mice was characterized and analyzed using high-throughput RNA sequencing. Immunohistochemistry staining was used to further assess the harmful effects of HSD on protein expression of genes associated with immunity, fibrosis, and apoptosis in male and female mice. Results HSD drastically altered the cardiac transcriptome compared to that of the normal heart in both male and female mice and had a sex-specific effect on the cardiac composition in the transcriptome. HSD produced various differentially expressed genes and affected different KEGG pathways of the transcriptome in male and female mice. Furthermore, we found that HSD induced different pathways of cardiovascular disease in the male mice and female mice. The pathway of hypertrophic cardiomyopathy is significantly enriched in HSD-treated male mice, while the pathway of dilated cardiomyopathy is significantly enriched in HSD-treated female mice. Finally, metabolism, immunity, fibrosis, and apoptosis in the mouse heart showed sex-specific changes predicting cardiac damage. Conclusion Our results demonstrate that HSD adversely impacts cardiac structure and function by affecting the metabolism, immunity, fibrosis, and apoptosis in the murine heart and induces the mouse to suffer from sex-specific cardiovascular disease. This study provides a new perspective and basis for the differences in the pharmacology and interventional treatment of sex-specific cardiovascular diseases induced by HSD in men and women.
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Affiliation(s)
- Xiuli Chen
- Obstetrical Department, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Haiying Wu
- Obstetrical Department, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
- *Correspondence: Shenzhen Huang
| | - Shenzhen Huang
- Henan Eye Institute, Henan Eye Hospital and Henan Key Laboratory of Ophthalmology and Visual Science, Henan Provincial People's Hospital, People's Hospital of Henan University, People's Hospital of Zhengzhou University, Zhengzhou, China
- Haiying Wu
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2
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Słabiak-Błaż N, Piecha G. Endogenous Mammalian Cardiotonic Steroids-A New Cardiovascular Risk Factor?-A Mini-Review. Life (Basel) 2021; 11:life11080727. [PMID: 34440471 PMCID: PMC8398695 DOI: 10.3390/life11080727] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 07/18/2021] [Accepted: 07/20/2021] [Indexed: 12/19/2022] Open
Abstract
The role of endogenous mammalian cardiotonic steroids (CTS) in the physiology and pathophysiology of the cardiovascular system and the kidneys has interested researchers for more than 20 years. Cardiotonic steroids extracted from toads or plants, such as digitalis, have been used to treat heart disease since ancient times. CTS, also called endogenous digitalis-like factors, take part in the regulation of blood pressure and sodium homeostasis through their effects on the transport enzyme called sodium–potassium adenosine triphosphatase (Na/K-ATPase) in renal and cardiovascular tissue. In recent years, there has been increasing evidence showing deleterious effects of CTS on the structure and function of the heart, vasculature and kidneys. Understanding the role of CTS may be useful in the development of potential new therapeutic strategies.
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Łabno-Kirszniok K, Kujawa-Szewieczek A, Wiecek A, Piecha G. The Effects of Short-Term Changes in Sodium Intake on Plasma Marinobufagenin Levels in Patients with Primary Salt-Sensitive and Salt-Insensitive Hypertension. Nutrients 2021; 13:nu13051502. [PMID: 33946894 PMCID: PMC8147121 DOI: 10.3390/nu13051502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 04/22/2021] [Accepted: 04/26/2021] [Indexed: 11/25/2022] Open
Abstract
Increased marinobufagenin (MBG) synthesis has been suggested in response to high dietary salt intake. The aim of this study was to determine the effects of short-term changes in sodium intake on plasma MBG levels in patients with primary salt-sensitive and salt-insensitive hypertension. In total, 51 patients with primary hypertension were evaluated during acute sodium restriction and sodium loading. Plasma or serum concentrations of MBG, natriuretic pro-peptides, aldosterone, sodium, potassium, as well as hematocrit (Hct) value, plasma renin activity (PRA) and urinary sodium and potassium excretion were measured. Ambulatory blood pressure monitoring (ABPM) and echocardiography were performed at baseline. In salt-sensitive patients with primary hypertension plasma MBG correlated positively with diastolic blood pressure (ABPM) and serum NT-proANP concentration at baseline and with serum NT-proANP concentration after dietary sodium restriction. In this subgroup plasma MBG concentration decreased during sodium restriction, and a parallel increase of PRA was observed. Acute salt loading further decreased plasma MBG concentration in salt-sensitive subjects in contrast to salt insensitive patients. No correlation was found between plasma MBG concentration and left ventricular mass index. In conclusion, in salt-sensitive hypertensive patients plasma MBG concentration correlates with 24-h diastolic blood pressure and dietary sodium restriction reduces plasma MBG levels. Decreased MBG secretion in response to acute salt loading may play an important role in the pathogenesis of salt sensitivity.
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Affiliation(s)
| | | | | | - Grzegorz Piecha
- Correspondence: ; Tel.: +48-322-591-429; Fax: +48-322-553-726
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4
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Pirkmajer S, Bezjak K, Matkovič U, Dolinar K, Jiang LQ, Miš K, Gros K, Milovanova K, Pirkmajer KP, Marš T, Kapilevich L, Chibalin AV. Ouabain Suppresses IL-6/STAT3 Signaling and Promotes Cytokine Secretion in Cultured Skeletal Muscle Cells. Front Physiol 2020; 11:566584. [PMID: 33101052 PMCID: PMC7544989 DOI: 10.3389/fphys.2020.566584] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 08/25/2020] [Indexed: 12/16/2022] Open
Abstract
The cardiotonic steroids (CTS), such as ouabain and marinobufagenin, are thought to be adrenocortical hormones secreted during exercise and the stress response. The catalytic α-subunit of Na,K-ATPase (NKA) is a CTS receptor, whose largest pool is located in skeletal muscles, indicating that muscles are a major target for CTS. Skeletal muscles contribute to adaptations to exercise by secreting interleukin-6 (IL-6) and plethora of other cytokines, which exert paracrine and endocrine effects in muscles and non-muscle tissues. Here, we determined whether ouabain, a prototypical CTS, modulates IL-6 signaling and secretion in the cultured human skeletal muscle cells. Ouabain (2.5–50 nM) suppressed the abundance of STAT3, a key transcription factor downstream of the IL-6 receptor, as well as its basal and IL-6-stimulated phosphorylation. Conversely, ouabain (50 nM) increased the phosphorylation of ERK1/2, Akt, p70S6K, and S6 ribosomal protein, indicating activation of the ERK1/2 and the Akt-mTOR pathways. Proteasome inhibitor MG-132 blocked the ouabain-induced suppression of the total STAT3, but did not prevent the dephosphorylation of STAT3. Ouabain (50 nM) suppressed hypoxia-inducible factor-1α (HIF-1α), a modulator of STAT3 signaling, but gene silencing of HIF-1α and/or its partner protein HIF-1β did not mimic effects of ouabain on the phosphorylation of STAT3. Ouabain (50 nM) failed to suppress the phosphorylation of STAT3 and HIF-1α in rat L6 skeletal muscle cells, which express the ouabain-resistant α1-subunit of NKA. We also found that ouabain (100 nM) promoted the secretion of IL-6, IL-8, GM-CSF, and TNF-α from the skeletal muscle cells of healthy subjects, and the secretion of GM-CSF from cells of subjects with the type 2 diabetes. Marinobufagenin (10 nM), another important CTS, did not alter the secretion of these cytokines. In conclusion, our study shows that ouabain suppresses the IL-6 signaling via STAT3, but promotes the secretion of IL-6 and other cytokines, which might represent a negative feedback in the IL-6/STAT3 pathway. Collectively, our results implicate a role for CTS and NKA in regulation of the IL-6 signaling and secretion in skeletal muscle.
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Affiliation(s)
- Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Katja Bezjak
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Urška Matkovič
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Klemen Dolinar
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Lake Q Jiang
- Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Katarina Gros
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Kseniya Milovanova
- Department of Sports and Health Tourism, Sports Physiology and Medicine, National Research Tomsk State University, Tomsk, Russia
| | - Katja Perdan Pirkmajer
- Department of Rheumatology, University Medical Centre Ljubljana, Ljubljana, Slovenia.,Department of Internal Medicine, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Tomaž Marš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Leonid Kapilevich
- Department of Sports and Health Tourism, Sports Physiology and Medicine, National Research Tomsk State University, Tomsk, Russia.,Central Scientific Laboratory, Siberian State Medical University, Tomsk, Russia
| | - Alexander V Chibalin
- Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
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Paczula A, Wiecek A, Piecha G. Cardiotonic Steroids-A Possible Link Between High-Salt Diet and Organ Damage. Int J Mol Sci 2019; 20:ijms20030590. [PMID: 30704040 PMCID: PMC6386955 DOI: 10.3390/ijms20030590] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 01/24/2019] [Accepted: 01/28/2019] [Indexed: 02/07/2023] Open
Abstract
High dietary salt intake has been listed among the top ten risk factors for disability-adjusted life years. We discuss the role of endogenous cardiotonic steroids in mediating the dietary salt-induced hypertension and organ damage.
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Affiliation(s)
- Aneta Paczula
- Department of Nephrology, Transplantation and Internal Medicine, Medical University of Silesia, Francuska 20-24, 40-027 Katowice, Poland.
| | - Andrzej Wiecek
- Department of Nephrology, Transplantation and Internal Medicine, Medical University of Silesia, Francuska 20-24, 40-027 Katowice, Poland.
| | - Grzegorz Piecha
- Department of Nephrology, Transplantation and Internal Medicine, Medical University of Silesia, Francuska 20-24, 40-027 Katowice, Poland.
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Dietary Sodium Restriction Reduces Arterial Stiffness, Vascular TGF-β-Dependent Fibrosis and Marinobufagenin in Young Normotensive Rats. Int J Mol Sci 2018; 19:ijms19103168. [PMID: 30326586 PMCID: PMC6214093 DOI: 10.3390/ijms19103168] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 09/14/2018] [Accepted: 10/10/2018] [Indexed: 12/27/2022] Open
Abstract
High salt (HS) intake stimulates the production of marinobufagenin (MBG), an endogenous steroidal Na/K-ATPase ligand, which activates profibrotic signaling. HS is accompanied by a blood pressure (BP) increase in salt-sensitive hypertension, but not in normotensive animals. Here, we investigated whether HS stimulates MBG production and activates transforming growth factor-beta (TGF-β) profibrotic signaling in young normotensive rats, and whether these changes can be reversed by reducing salt to a normal salt (NS) level. Three-month old male Sprague–Dawley rats received NS for 4 and 8 weeks (0.5% NaCl; NS4 and NS8), or HS for 4 and 8 weeks (4% NaCl; HS4 and HS8), or HS for 4 weeks followed by NS for 4 weeks (HS4/NS4), n = 8/group. Systolic BP (SBP), pulse wave velocity (PWV), MBG excretion, aortic collagen 1α2, collagen 4α1 and TGF-β, Smad2, Smad3, Fli-1 mRNA, and total collagen abundance were measured at baseline (BL), and on weeks 4 and 8. Statistical analysis was performed using one-way ANOVA. SBP was not affected by HS (125 ± 5 and 126 ± 6 vs. 128 ± 7 mmHg, HS4 and HS8 vs. BL, p > 0.05). HS increased MBG (164 ± 19 vs. 103 ± 19 pmol/24 h/kg, HS4 vs. BL, p < 0.05) and PWV (3.7 ± 0.2 vs. 2.7 ± 0.2 m/s, HS4 vs. NS4, p < 0.05). HS8 was associated with a further increase in MBG and PWV, with an increase in aortic Col1a2 80%), Col4a1 (50%), Tgfb1 (30%), Smad2 (30%) and Smad3 (45%) mRNAs, and aortic wall collagen (180%) vs. NS8 (all p < 0.05). NS following HS downregulated HS-induced factors: in HS4/NS4, the MBG level was 91 ± 12 pmol/24 h/kg (twofold lower than HS8, p < 0.01), PWV was 3.7 ± 0.3 vs. 4.7 ± 0.2 m/s (HS4/NS4 vs. HS8, p < 0.05), aortic wall Tgfb1, Col1a2, Col4a1, Smad2, Smad3 mRNAs, and collagen abundance were reversed by salt reduction to the BL levels (p < 0.05). HS was associated with an activation of TGF-β signaling, aortic fibrosis and aortic stiffness accompanied by an MBG increase in the absence of SBP changes in young normotensive rats. The reduction of dietary salt following HS decreased MBG, PWV, aortic wall collagen and TGF-β. Thus, HS-induced aortic stiffness in normotensive animals occurred in the context of elevated MBG, which may activate SMAD-dependent TGF-β pro-fibrotic signaling. This data suggests that a decrease in salt consumption could help to restore aortic elasticity and diminish the risk of cardiovascular disease by reducing the production of the pro-fibrotic factor MBG.
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7
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Petrushanko IY, Mitkevich VA, Lakunina VA, Anashkina AA, Spirin PV, Rubtsov PM, Prassolov VS, Bogdanov NB, Hänggi P, Fuller W, Makarov AA, Bogdanova A. Cysteine residues 244 and 458-459 within the catalytic subunit of Na,K-ATPase control the enzyme's hydrolytic and signaling function under hypoxic conditions. Redox Biol 2017; 13:310-319. [PMID: 28601781 PMCID: PMC5470536 DOI: 10.1016/j.redox.2017.05.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Revised: 03/16/2017] [Accepted: 05/26/2017] [Indexed: 12/21/2022] Open
Abstract
Our previous findings suggested that reversible thiol modifications of cysteine residues within the actuator (AD) and nucleotide binding domain (NBD) of the Na,K-ATPase may represent a powerful regulatory mechanism conveying redox- and oxygen-sensitivity of this multifunctional enzyme. S-glutathionylation of Cys244 in the AD and Cys 454-458-459 in the NBD inhibited the enzyme and protected cysteines' thiol groups from irreversible oxidation under hypoxic conditions. In this study mutagenesis approach was used to assess the role these cysteines play in regulation of the Na,K-ATPase hydrolytic and signaling functions. Several constructs of mouse α1 subunit of the Na,K-ATPase were produced in which Cys244, Cys 454-458-459 or Cys 244-454-458-459 were replaced by alanine. These constructs were expressed in human HEK293 cells. Non-transfected cells and those expressing murine α1 subunit were exposed to hypoxia or treated with oxidized glutathione (GSSG). Both conditions induced inhibition of the wild type Na,K-ATPase. Enzymes containing mutated mouse α1 lacking Cys244 or all four cysteines (Cys 244-454-458-459) were insensitive to hypoxia. Inhibitory effect of GSSG was observed for wild type murine Na,K-ATPase, but was less pronounced in Cys454-458-459Ala mutant and completely absent in the Cys244Ala and Cys 244-454-458-459Ala mutants. In cells, expressing wild type enzyme, ouabain induced activation of Src and Erk kinases under normoxic conditions, whereas under hypoxic conditions this effect was inversed. Cys454-458-459Ala substitution abolished Src kinase activation in response to ouabain treatment, uncoupled Src from Erk signaling, and interfered with O2-sensitivity of Na,K-ATPase signaling function. Moreover, modeling predicted that S-glutathionylation of Cys 458 and 459 should prevent inhibitory binding of Src to NBD. Our data indicate for the first time that cysteine residues within the AD and NBD influence hydrolytic as well as receptor function of the Na,K-ATPase and alter responses of the enzyme to hypoxia or upon treatment with cardiotonic steroids.
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Affiliation(s)
- Irina Yu Petrushanko
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Vladimir A Mitkevich
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Valentina A Lakunina
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Anastasia A Anashkina
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Pavel V Spirin
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Peter M Rubtsov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Vladimir S Prassolov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Nikolay B Bogdanov
- Institute of Veterinary Physiology, Vetsuisse Faculty and the Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Pascal Hänggi
- Institute of Veterinary Physiology, Vetsuisse Faculty and the Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - William Fuller
- Cardiovascular and Diabetes Medicine, School of Medicine, University of Dundee, Dundee, UK
| | - Alexander A Makarov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Anna Bogdanova
- Institute of Veterinary Physiology, Vetsuisse Faculty and the Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland.
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Abstract
Significant hemodynamic changes ensue with aging, leading to an ever-growing epidemic of hypertension. Alterations in central arterial properties play a major role in these hemodynamic changes. These alterations are characterized by an initial decline in aortic distensibility and an increase of diastolic blood pressure, followed by a sharp increase in pulse wave velocity (PWV), and an increase in pulse pressure (PP) beyond the sixth decade. However, the trajectories of PWV and PP diverge with advancing age. There is an increased prevalence of salt-sensitive hypertension with advancing age that is, in part, mediated by marinobufagenin, an endogenous sodium pump ligand.
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Affiliation(s)
- Majd AlGhatrif
- Laboratory of Cardiovascular Science, NIA, NIH, Baltimore, MD, USA; Department of Medicine, Johns Hopkins Bayview Medical Center, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Mingyi Wang
- Laboratory of Cardiovascular Science, NIA, NIH, Baltimore, MD, USA
| | - Olga V Fedorova
- Laboratory of Cardiovascular Science, NIA, NIH, Baltimore, MD, USA
| | - Alexei Y Bagrov
- Laboratory of Cardiovascular Science, NIA, NIH, Baltimore, MD, USA
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, NIA, NIH, Baltimore, MD, USA.
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Grigorova YN, Juhasz O, Zernetkina V, Fishbein KW, Lakatta EG, Fedorova OV, Bagrov AY. Aortic Fibrosis, Induced by High Salt Intake in the Absence of Hypertensive Response, is Reduced by a Monoclonal Antibody to Marinobufagenin. Am J Hypertens 2016; 29:641-6. [PMID: 26350300 DOI: 10.1093/ajh/hpv155] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 08/13/2015] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Marinobufagenin (MBG) is an endogenous Na/K-ATPase inhibitor, a natriuretic and a vasoconstrictor. MBG is implicated in salt-sensitive hypertension, cardiac hypertrophy, and initiate the pro-fibrotic signaling. Previously it was demonstrated that immunoneutralization of an endogenous MBG by 3E9 anti-MBG-antibody (mAb) in vivo lowered blood pressure (BP) and reversed cardiac fibrosis in salt-sensitive, and in partially nephrectomized rats. In the present study, we investigated whether mAb alleviates vascular remodeling induced in normotensive rats on high salt intake. METHODS Wistar rats (5 months old) received normal (CTRL; n = 8) or high salt intake (2% NaCl in drinking water) for 4 weeks ( n = 16). Rats from the group on a high salt intake were administered vehicle (SALT; n = 8) or mAb (50 µg/kg) (SALT-AB; n = 8) during the last week of high salt diet. BP, erythrocyte Na/K-ATPase activity, levels of MBG in plasma and 24-hour urine, and sensitivity of aortic explants to the vasorelaxant effect of sodium nitroprusside (SNP) were measured. Aortic collagen abundance was determined immunohistochemically. RESULTS In SALT vs. CTRL, heightened levels of MBG were associated with inhibition of erythrocyte Na/K-ATPase in the absence of BP changes. High salt intake was accompanied by a 2.5-fold increase in aortic collagen abundance and by a reduction of sensitivity of aortic explants to the vasorelaxant effect of SNP following endothelin-1-induced constriction. In the SALT-AB group, all NaCl-mediated effects were reversed by immunoneutralization of MBG. CONCLUSIONS High salt intake in young normotensive rats can induce vascular fibrosis via pressure-independent/MBG-dependent mechanisms, and this remodeling is reduced by immunoneutralization of MBG.
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Affiliation(s)
- Yulia N Grigorova
- National Institute on Aging, NIH, Baltimore, Maryland, USA; Federal Almazov Medical Research Centre, and Sechenov Institute of Evolutionary Physiology and Biochemistry, St Petersburg, Russia
| | - Ondrej Juhasz
- National Institute on Aging, NIH, Baltimore, Maryland, USA
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Jablonski KL, Fedorova OV, Racine ML, Geolfos CJ, Gates PE, Chonchol M, Fleenor BS, Lakatta EG, Bagrov AY, Seals DR. Dietary sodium restriction and association with urinary marinobufagenin, blood pressure, and aortic stiffness. Clin J Am Soc Nephrol 2013; 8:1952-9. [PMID: 23929930 DOI: 10.2215/cjn.00900113] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND AND OBJECTIVES Systolic BP and large elastic artery stiffness both increase with age and are reduced by dietary sodium restriction. Production of the natriuretic hormone marinobufagenin, an endogenous α1 Na+,K+-ATPase inhibitor, is increased in salt-sensitive hypertension and contributes to the rise in systolic BP during sodium loading. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS The hypothesis was that dietary sodium restriction performed in middle-aged/older adults (eight men and three women; 60 ± 2 years) with moderately elevated systolic BP (139 ± 2/83 ± 2 mmHg) would reduce urinary marinobufagenin excretion as well as systolic BP and aortic pulse-wave velocity (randomized, placebo-controlled, and crossover design). This study also explored the associations among marinobufagenin excretion with systolic BP and aortic pulse-wave velocity across conditions of 5 weeks of a low-sodium (77 ± 9 mmol/d) and 5 weeks of a normal-sodium (144 ± 7 mmol/d) diet. RESULTS Urinary marinobufagenin excretion (weekly measurements; 25.4 ± 1.8 versus 30.7 ± 2.1 pmol/kg per day), systolic BP (127 ± 3 versus 138 ± 5 mmHg), and aortic pulse-wave velocity (700 ± 40 versus 843 ± 36 cm/s) were lower during the low- versus normal-sodium condition (all P<0.05). Across all weeks, marinobufagenin excretion was related with systolic BP (slope=0.61, P<0.001) and sodium excretion (slope=0.46, P<0.001). These associations persisted during the normal- but not the low-sodium condition (both P<0.005). Marinobufagenin excretion also was associated with aortic pulse-wave velocity (slope=0.70, P=0.02) and endothelial cell expression of NAD(P)H oxidase-p47phox (slope=0.64, P=0.006). CONCLUSIONS These results show, for the first time in humans, that dietary sodium restriction reduces urinary marinobufagenin excretion and that urinary marinobufagenin excretion is positively associated with systolic BP, aortic stiffness (aortic pulse-wave velocity), and endothelial cell expression of the oxidant enzyme NAD(P)H oxidase. Importantly, marinobufagenin excretion is positively related to systolic BP over ranges of sodium intake typical of an American diet, extending previous observations in rodents and humans fed experimentally high-sodium diets.
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Affiliation(s)
- Kristen L Jablonski
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado;, †Intramural Research Program, Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, Maryland;, ‡Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, United Kingdom, §Division of Renal Diseases and Hypertension, University of Colorado Denver Anschutz Medical Center, Aurora, Colorado
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Regulation of central Na+ detection requires the cooperative action of the NaX channel and α1 Isoform of Na+/K+-ATPase in the Na+-sensor neuronal population. J Neurosci 2013; 33:3067-78. [PMID: 23407962 DOI: 10.1523/jneurosci.4801-12.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The median preoptic nucleus (MnPO) holds a strategic position in the hypothalamus. It is adjacent to the third ventricle; hence, it can directly access the ionic composition of the CSF. MnPO neurons play a critical role in hydromineral homeostasis regulation by acting as central sensors of extracellular Na(+) concentration ([Na(+)](ext)). The mechanism underlying Na(+) sensing involves the atypical Na(+) channel, Na(X). Here we sought to determine whether Na(+) influx in Na(+) sensors is actively regulated via interaction with other membrane proteins involved in cellular Na(+) homeostasis, such as Na(+)/K(+)-ATPase. The Na(+)/K(+)-ATPase role was investigated using patch-clamp recordings in rat MnPO dissociated neurons. Na(+) current evoked with hypernatriuric solution was diminished in the absence of ATP/GTP, indicating that Na(+)/K(+)-ATPase play a central role in [Na(+)](ext) detection. Specific blockers of α1 and α3 isoforms of Na(+)/K(+)-ATPase, ouabain or strophanthidin, inhibited this Na(+) current. However, strophanthidin, which selectively blocks the α1 isoform, was more effective in blocking Na(+) current, suggesting that the Na(+)/K(+)-ATPase-α1 isoform is specifically involved in [Na(+)](ext) detection. Although strophanthidin did not alter either the membrane resistance or the Na(+) reversal potential, the conductance and the permeability of the Na(X) channel decreased significantly. Our results suggest that Na(+)/K(+)-ATPase interacts with the Na(X) channel and regulates the high [Na(+)](ext)-evoked Na(+) current via influencing the Na(+) influx rate. This study describes a novel intracellular regulatory pathway of [Na(+)](ext) detection in MnPO neurons. The α1 isoform of Na(+)/K(+)-ATPase acts as a direct regulatory partner of the Na(X) channel and influences Na(+) influx via controlling the Na(+) permeability of the channel.
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DOCA-salt hypertension does not require the ouabain-sensitive binding site of the α2 Na,K-ATPase. Am J Hypertens 2012; 25:421-9. [PMID: 22258333 DOI: 10.1038/ajh.2011.255] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND We have shown that the ouabain-sensitive α2 Na,K-ATPase is required for adrenocorticotropic hormone (ACTH)-induced hypertension and gestational blood pressure regulation. It is therefore of interest to explore whether this binding site participates in the development of other forms of hypertension, such as deoxycorticosterone acetate (DOCA)-salt using mutant mice with altered sensitivity to ouabain. METHODS Wild-type (α1 ouabain-resistant, α2 ouabain-sensitive: α(R/R)α2(S/S)), α1-resistant, α2-resistant (α1(R/R)α2(R/R)) and α1-sensitive, α2-resistant (α1(S/S)α2(R/R)) mice were uninephrectomized and implanted with DOCA pellets. The animals were given either tap water or 1% NaCl, and blood pressure was measured before and after DOCA. RESULTS DOCA-salt-treated α1(R/R)α2(R/R) mice developed hypertension to the same extent as α1(R/R)α2(S/S) mice (wild type), and the α1(S/S)α2(R/R) mice given DOCA-salt also showed no difference from the other two genotypes. The expression of the α1 isoform was not changed by DOCA-salt treatment in either α1(R/R)α2(S/S) or α1(R/R)α2(R/R) mice. However, the α2 subunit was expressed at substantially higher levels in the hearts of α1(R/R)α2(R/R) than α1(R/R)α2(S/S) mice, regardless of treatment. Plasma levels of ouabain did not change consistently, but those of marinobufagenin were modestly higher in DOCA-salt treated mice relatively to those without salt. CONCLUSIONS The ouabain-binding site of either the α1 or α2 Na,K-ATPase subunit does not play an essential role in the development of DOCA-salt hypertension in this mouse model. These findings indicate that the underlying mechanisms of hypertension induced by DOCA-salt treatment are different from those of ACTH-induced hypertension.
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Kirshenbaum GS, Saltzman K, Rose B, Petersen J, Vilsen B, Roder JC. Decreased neuronal Na+, K+ -ATPase activity in Atp1a3 heterozygous mice increases susceptibility to depression-like endophenotypes by chronic variable stress. GENES BRAIN AND BEHAVIOR 2011; 10:542-50. [PMID: 21418141 DOI: 10.1111/j.1601-183x.2011.00691.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Unipolar depression and bipolar depression are prevalent and debilitating diseases in need of effective novel treatments. It is becoming increasingly evident that depressive disorders manifest from a combination of inherited susceptibility genes and environmental stress. Genetic mutations resulting in decreased neuronal Na(+) ,K(+) -ATPase (sodium-potassium adenosine triphosphatase) activity may put individuals at risk for depression given that decreased Na(+) ,K(+) -ATPase activity is observed in depressive disorders and animal models of depression. Here, we show that Na(+) ,K(+) -ATPase α3 heterozygous mice (Atp1a3(+/-) ), with 15% reduced neuronal Na(+) ,K(+) -ATPase activity, are vulnerable to develop increased depression-like endophenotypes in a chronic variable stress (CVS) paradigm compared to wild-type littermates (Atp1a3(+/+) ). In Atp1a3(+/+) mice CVS did not decrease Na(+) ,K(+) -ATPase activity, however led to despair-like behavior in the tail suspension test (TST), anhedonia in a sucrose preference test and a minimal decrease in sociability, whereas in Atp1a3(+/-) mice CVS decreased neuronal Na(+) ,K(+) -ATPase activity to 33% of wild-type levels, induced despair-like behavior in the TST, anhedonia in a sucrose preference test, anxiety in the elevated plus maze, a memory deficit in a novel object recognition task and sociability deficits in a social interaction test. We found that a mutation that decreases neuronal Na(+) ,K(+) -ATPase activity interacts with stress to exacerbate depression. Furthermore, we observed an interesting correlation between Na(+) ,K(+) -ATPase activity and mood that may relate to both unipolar depression and bipolar disorder. Pharmaceuticals that increase Na(+) ,K(+) -ATPase activity or block endogenous Na(+) , K(+) -ATPase inhibition may provide effective treatment for depressive disorders and preclude depression in susceptible individuals.
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Affiliation(s)
- G S Kirshenbaum
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital and Institute of Medical Science, University of Toronto, 600 University Avenue, Toronto, Ontario, Canada.
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Lingrel JB. The physiological significance of the cardiotonic steroid/ouabain-binding site of the Na,K-ATPase. Annu Rev Physiol 2010; 72:395-412. [PMID: 20148682 DOI: 10.1146/annurev-physiol-021909-135725] [Citation(s) in RCA: 220] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The Na,K-ATPase is the membrane "pump" that generates the Na(+) and K(+) gradients across the plasma membrane that drives many physiological processes. This enzyme is highly sensitive to inhibition by cardiotonic steroids, most notably the digitalis/ouabain class of compounds, which have been used for centuries to treat congestive heart failure and arrhythmias. The amino acids that constitute the ouabain-binding site are highly conserved across the evolutionary spectrum. This could be fortuitous or could result from this site being conserved because it has an important biological function. New physiological approaches using genetically engineered mice are being used to define the biological significance of the "receptor function" of the Na,K-ATPase and its regulation by potential endogenous cardiotonic steroid-like compounds. These studies extend the reach of earlier studies involving the biochemical purification of endogenous regulatory ligands.
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Affiliation(s)
- Jerry B Lingrel
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0524, USA.
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15
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Fedorova OV, Shapiro JI, Bagrov AY. Endogenous cardiotonic steroids and salt-sensitive hypertension. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1230-6. [PMID: 20347967 DOI: 10.1016/j.bbadis.2010.03.011] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 03/18/2010] [Accepted: 03/20/2010] [Indexed: 12/12/2022]
Abstract
Endogenous cardiotonic steroids (CTS), also called digitalis like factors, have been postulated to play important roles in pathogenesis of hypertension for nearly half of a century. For the past 50 years biomedical scientists have been in quest of an unidentified factor or hormone that both increases blood pressure and renal sodium excretion; this "natriuretic hormone" was, in fact, postulated to interact with the Na/K-ATPase. Recent discoveries have led to the identification of steroid molecules which are present in humans, rodents and amphibians, and which, in a complex manner, interact with each other and with the other systems that regulate renal salt handling and contribute to the salt-sensitivity of blood pressure. Recent findings include the specific identification of endogenous cardenolide (endogenous ouabain) and bufadienolide (marinobufagenin) CTS in humans along with the delineation of mechanisms by which CTS can signal through the Na/K-ATPase. Although CTS were first considered important in the regulation of renal sodium transport and arterial pressure, more recent work implicates these hormones in the central regulation of blood pressure and regulation of cell growth, and development of cardiovascular and renal fibrosis in particular.
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Affiliation(s)
- Olga V Fedorova
- National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
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16
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Puschett JB, Agunanne E, Uddin MN. Marinobufagenin, resibufogenin and preeclampsia. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1246-53. [PMID: 20167272 DOI: 10.1016/j.bbadis.2010.02.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Revised: 01/15/2010] [Accepted: 02/06/2010] [Indexed: 11/18/2022]
Abstract
The bufodienolides are cardiac glycosides which have the ability to inhibit the enzyme, Na(+)/K(+) ATPase (sodium potassium adenosine triphosphatase). They are cardiac inotropes, cause vasoconstriction (and, potentially, hypertension) and are natriuretic. Evidence has accrued over time which supports the view that they are mechanistically involved in volume expansion-mediated hypertension. In this communication, the authors summarize data which support the view that the bufodienolides and, in particular, marinobufagenin (MBG) are involved in the pathogenesis of preeclampsia. In a rat model of the syndrome, MBG causes hypertension, proteinuria, intrauterine growth restriction and increased weight gain. All of these phenotypic characteristics are prevented by an antagonist to MBG, resibufogenin (RBG). The "preeclamptic" animals also develop a vascular leak syndrome, resulting in hemoconcentration. Abnormalities in the MAPK (mitogen-activated protein kinase) system play a role in the mechanism by which MBG produces the abnormalities in the pregnant rat. Studies to discover the relevance of these findings to human preeclampsia are currently underway in several laboratories and clinics.
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Affiliation(s)
- J B Puschett
- Department of Medicine, Texas A&M Health Science Center, Temple, TX 76508, USA.
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17
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Bagrov AY, Agalakova NI, Kashkin VA, Fedorova OV. Endogenous cardiotonic steroids and differential patterns of sodium pump inhibition in NaCl-loaded salt-sensitive and normotensive rats. Am J Hypertens 2009; 22:559-63. [PMID: 19229192 DOI: 10.1038/ajh.2009.22] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Endogenous sodium pump inhibitors promote sodium excretion in normotensives and contribute to vasoconstriction in NaCl-sensitive hypertension. Marinobufagenin (MBG), an endogenous bufadienolide inhibitor of alpha-1 sodium pump, contributes to hypertension in Dahl salt-sensitive rats (DS). We hypothesized that in NaCl-loaded DS and normotensive Sprague-Dawley rats (S-D), MBG would elicit different patterns of sodium pump inhibition. METHODS We compared systolic blood pressure (SBP), renal sodium excretion, activity of the sodium pump in aorta and renal medulla, and levels of MBG, atrial natriuretic peptide (ANP), and cyclic guanosine monophosphate (cGMP) in salt-loaded DS and S-D (20% NaCl, 2.5 ml/kg, intraperitoneally). RESULTS NaCl loading produced sustained elevations in renal MBG excretion in both DS (2.41 +/- 0.24 vs. 0.79 +/- 0.08 pmol/h/kg, P < 0.01) and S-D (1.97 +/- 0.37 vs. 0.60 +/- 0.07 pmol/h/kg, P < 0.01) vs. that at baseline (n = 10 for each group). In NaCl-loaded DS, SBP rose by 18 mm Hg (P < 0.01) and aortic sodium pump was inhibited by 22% (P < 0.05 vs. control), while in S-D, SBP and activity of aortic sodium pump did not change. NaCl-loaded S-D excreted twice as much sodium as DS; in S-D, renal sodium pump was inhibited by 24% vs. 14% inhibition in DS (P < 0.05). NaCl loading elicited increases in plasma ANP and in renal cGMP excretion in S-D but not in DS. CONCLUSIONS Our present observations demonstrate that in NaCl-loaded S-D and DS, a comparable MBG response is associated with preferential inhibition of the sodium pump in the kidney and in vascular smooth muscle, respectively, resulting in an adaptive natriuresis in S-D but sodium retention and pressor response in DS.
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18
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Bagrov AY, Shapiro JI, Fedorova OV. Endogenous cardiotonic steroids: physiology, pharmacology, and novel therapeutic targets. Pharmacol Rev 2009; 61:9-38. [PMID: 19325075 PMCID: PMC2763610 DOI: 10.1124/pr.108.000711] [Citation(s) in RCA: 383] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Endogenous cardiotonic steroids (CTS), also called digitalis-like factors, have been postulated to play important roles in health and disease for nearly half a century. Recent discoveries, which include the specific identification of endogenous cardenolide (endogenous ouabain) and bufadienolide (marinobufagenin) CTS in humans along with the delineation of an alternative mechanism by which CTS can signal through the Na(+)/K(+)-ATPase, have increased the interest in this field substantially. Although CTS were first considered important in the regulation of renal sodium transport and arterial pressure, more recent work implicates these hormones in the regulation of cell growth, differentiation, apoptosis, and fibrosis, the modulation of immunity and of carbohydrate metabolism, and the control of various central nervous functions and even behavior. This review focuses on the physiological interactions between CTS and other regulatory systems that may be important in the pathophysiology of essential hypertension, preeclampsia, end-stage renal disease, congestive heart failure, and diabetes mellitus. Based on our increasing understanding of the regulation of CTS as well as the molecular mechanisms of these hormone increases, we also discuss potential therapeutic strategies.
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Affiliation(s)
- Alexei Y Bagrov
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Dr., Baltimore, MD 21224, USA.
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19
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Schoner W, Scheiner-Bobis G. Role of endogenous cardiotonic steroids in sodium homeostasis. Nephrol Dial Transplant 2008; 23:2723-9. [PMID: 18556748 DOI: 10.1093/ndt/gfn325] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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20
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Bagrov YY, Manusova NB, Frolova EV, Egorova IA, Kashkin VA, Tapilskaya NI, Fedorova OV, Bagrov AY. Endogenous sodium pump inhibitors, diabetes mellitus and preeclampsia Preliminary observations and a hypothesis. ACTA ACUST UNITED AC 2007; 14:147-51. [PMID: 17942287 DOI: 10.1016/j.pathophys.2007.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Endogenous inhibitors of the Na/K-ATPase (NKA) and diabetes mellitus (DM) are both risk factors for preeclampsia and NaCl sensitive hypertension. Our goal was to test the hypothesis that NaCl supplementation, induces preeclampsia-like symptoms in pregnant rats with DM via stimulation of marinobufagenin (MBG), a natriuretic and vasoconstrictor inhibitor of the NKA. Type 2 DM in female Sprague-Dawley rats was induced by administration of 65mg/kg streptozotocin at day 4 post-partum. In intact rats, pregnancy was associated with a twofold increase in MBG levels and a mild impairment in glucose tolerance. Pregnant rats with DM exhibited fetal macrosomia, greater impairment of glucose tolerance, and higher levels of MBG as compared to that in normal pregnant rats. As compared to intact pregnant rats, NaCl supplementation of diabetic pregnant rats (drinking 1.8% NaCl during days 12-19 of pregnancy) was associated with an increase in systolic blood pressure, decreased fetal and placental weight, fivefold elevation of MBG excretion, and 42% inhibition of NKA in erythrocytes. In nonpregnant rats, in vivo pretreatment with anti-MBG antibody produced an exaggerated response of plasma levels of glucose and insulin in oral glucose tolerance test. These results suggest that MBG is a common factor in the pathogenesis of DM and preeclampsia, and that regulation of glucose tolerance may be one of the physiological functions of endogenous cardiotonic steroids.
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Affiliation(s)
- Yakov Y Bagrov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, Russia
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21
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Danchuk S, Sukhanov S, Horvat D, Uddin MN, Puschett JB. Effects of resibufogenin in experimental hypertension. Am J Nephrol 2007; 28:8-13. [PMID: 17890853 DOI: 10.1159/000108756] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Accepted: 07/26/2007] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS There are two major pathophysiologic processes involved in the development of hypertension: (1) expanded extracellular fluid volume and (2) vasoconstriction. We have developed a model of preeclampsia in the rat, in which excessive volume expansion (VE) plays a role. These animals excrete increased amounts of the bufodienolide, marinobufagenin (MBG), even before their hypertension and proteinuria become established. Furthermore, their hypertension is corrected by administration of resibufogenin (RBG), a compound structurally similar to MBG. METHOD We studied two models of experimental hypertension in the nonpregnant animal, produced either by deoxycorticosterone acetate (DOCA)-salt administration or by angiotensin infusion. RESULTS RBG administered to the DOCA-salt rats lowered blood pressure and reduced proteinuria in the VE animals, but had no affect on the rats infused with angiotensin. Furthermore, although the production of superoxide anion in the aortas of both groups of hypertensive rats was increased over control, RBG reduced these levels to normal in the VE (DOCA-salt) animals only. RBG had no effect in the angiotensin-infused rats. The urinary excretion of angiotensinogen did not rise in VE-mediated hypertension, but did increase in the angiotensin-infused rats. CONCLUSIONS MBG plays an important role in the causation of hypertension in the VE rats, but not in the vasoconstrictive model. RBG is effective only in VE-mediated hypertension.
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Affiliation(s)
- S Danchuk
- Section of Nephrology and Hypertension, Department of Medicine, Tulane University School of Medicine, New Orleans, LA, USA
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Nesher M, Shpolansky U, Rosen H, Lichtstein D. The digitalis-like steroid hormones: new mechanisms of action and biological significance. Life Sci 2007; 80:2093-2107. [PMID: 17499813 DOI: 10.1016/j.lfs.2007.03.013] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Revised: 03/08/2007] [Accepted: 03/14/2007] [Indexed: 12/25/2022]
Abstract
Digitalis-like compounds (DLC) are a family of steroid hormones synthesized in and released from the adrenal gland. DLC, the structure of which resembles that of plant cardiac glycosides, bind to and inhibit the activity of the ubiquitous cell surface enzyme Na(+), K(+)-ATPase. However, there is a large body of evidence suggesting that the regulation of ion transport by Na(+), K(+)-ATPase is not the only physiological role of DLC. The binding of DLC to Na(+), K(+)-ATPase induces the activation of various signal transduction cascades that activate changes in intracellular Ca(++) homeostasis, and in specific gene expression. These, in turn, stimulate endocytosis and affect cell growth and proliferation. At the systemic level, DLC were shown to be involved in the regulation of major physiological parameters including water and salt homeostasis, cardiac contractility and rhythm, systemic blood pressure and behavior. Furthermore, the DLC system has been implicated in several pathological conditions, including cardiac arrhythmias, hypertension, cancer and depressive disorders. This review evaluates the evidence for the different aspects of DLC action and delineates open questions in the field.
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Affiliation(s)
- Maoz Nesher
- Department of Physiology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Uri Shpolansky
- Department of Physiology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Haim Rosen
- The Kuvin Center for the Study of Infectious and Tropical Diseases, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - David Lichtstein
- Department of Physiology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
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dos Santos L, Gonçalves MV, Vassallo DV, Oliveira EM, Rossoni LV. Effects of high sodium intake diet on the vascular reactivity to phenylephrine on rat isolated caudal and renal vascular beds: Endothelial modulation. Life Sci 2005; 78:2272-9. [PMID: 16289140 DOI: 10.1016/j.lfs.2005.09.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2005] [Accepted: 09/15/2005] [Indexed: 10/25/2022]
Abstract
High salt intake is involved in the genesis of hypertension and vascular changes in salt-sensitive patients. Although many mechanisms have been proposed, the underlying mechanisms of these alterations in healthy rats are not completely elucidated. The aim of this study was to investigate if male Wistar rats fed a high salt diet, NaCl 1.8% in drinking water for 4 weeks, develop changes in the pressor reactivity of isolated tail and renal vascular beds. Salt treatment increased mean arterial pressure (SALT = 124 +/- 2.2 vs. CT = 111 +/- 3.9 mmHg; p < 0.01) and urinary sodium excretion in the absence of changes in sodium plasma levels. Pressor reactivity was generated in isolated tail and kidney vascular beds as dose-response curves to phenylephrine (PHE = 0.01 to 300 microg). SALT increased the reactivity (E(max): SALT = 378 +/- 15.8 vs. CT = 282 +/- 10 mmHg; p < 0.01) without changing the sensitivity (pD(2)) to PHE in the tail vascular bed. However, these parameters did not change in the renal bed. In subsequent studies on the isolated caudal vascular bed, we found that endothelial damage, but not L-NAME (100 microM) or indomethacin (10 microM), abolished the increment in E(max) to PHE induced by SALT. On the other hand, losartan (100 microM) reduced E(max) in SALT to CT values. Additionally, local angiotensin-converting enzyme activity in segments from tail artery increased by 95%. In conclusion, 4 weeks of high salt diet increases blood pressure and induces specific territorial vascular changes in response to PHE. Results also suggest that the increment in E(max) in the tail vascular bed from SALT rats was endothelium-dependent and was mediated by the activation of the local renin-angiotensin system.
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Affiliation(s)
- Leonardo dos Santos
- Departamento de Ciências Fisiológicas, Centro Biomédico, Universidade Federal do Espírito Santo, Brazil
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Periyasamy SM, Liu J, Tanta F, Kabak B, Wakefield B, Malhotra D, Kennedy DJ, Nadoor A, Fedorova OV, Gunning W, Xie Z, Bagrov AY, Shapiro JI. Salt loading induces redistribution of the plasmalemmal Na/K-ATPase in proximal tubule cells. Kidney Int 2005; 67:1868-77. [PMID: 15840034 DOI: 10.1111/j.1523-1755.2005.00285.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND We have reported that digitalis-like substances (cardiotonic steroids), including marinobufagenin (MBG), induce endocytosis of the plasmalemmal Na/K-ATPase in LLC-PK1 cells. The current report addresses the potential relevance of plasmalemmal Na/K-ATPase redistribution to in vivo salt handling. METHODS Male Sprague-Dawley rats were given 1 week of a high salt (4.0% NaCl) or normal salt (0.4% NaCl) diet. Urinary sodium excretion, as well as MBG excretion, was monitored, and proximal tubules were isolated using a Percoll gradient method. Tubular (86)Rb uptake, Na/K-ATPase enzymatic activity, and Na/K-ATPase alpha1 subunit density were determined. RESULTS The high salt diet increased urinary sodium (17.8 +/- 1.8 vs. 2.5 +/- 0.3 mEq/day, P < 0.01) and MBG excretion (104 +/- 12 vs. 26 +/- 4 pmol/day), and decreased proximal tubular (86)Rb uptake (0.44 +/- 0.07 vs. 1.00 +/- 0.10, P < 0.01) and Na/K-ATPase enzymatic activity (5.1 +/- 1.1 vs. 9.9 +/- 1.6 micromol/mg pr/hr, P < 0.01) relative to the normal diet. Proximal tubular Na/K-ATPase alpha1 protein density was decreased in the plasmalemma fraction but increased in both early and late endosomes following the high salt diet. In rats fed a high salt diet, anti-MBG antibody caused a 60% reduction in urinary sodium excretion, substantial increases in proximal tubule (86)Rb uptake, and Na/K-ATPase enzymatic activity, as well as significant decreases in the early and late endosomal Na/K-ATPase alpha1 protein content. CONCLUSION These data suggest that redistribution of the proximal tubule Na/K-ATPase in response to endogenous cardiotonic steroids plays an important role in renal adaptation to salt loading.
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Fedorova OV, Kolodkin NI, Agalakova NI, Namikas AR, Bzhelyansky A, St-Louis J, Lakatta EG, Bagrov AY. Antibody to marinobufagenin lowers blood pressure in pregnant rats on a high NaCl intake. J Hypertens 2005; 23:835-42. [PMID: 15775789 DOI: 10.1097/01.hjh.0000163153.27954.33] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The pathogenesis of pre-eclampsia (PE), a major cause of maternal and fetal mortality, is not fully understood. Digitalis-like sodium pump ligands (SPLs) are believed to be implicated in PE, as illustrated by clinical observations that DIGIBIND, a digoxin antibody that binds SPLs, lowers blood pressure (BP) in PE. We recently reported that plasma levels of marinobufagenin (MBG), a vasoconstrictor SPL, are increased four-fold in patients with PE. In the present study, we tested whether a polyclonal antibody to MBG can lower BP in rats with pregnancy-associated hypertension. METHODS Systolic BP (SBP), 24-h renal excretion of MBG and endogenous ouabain (EO), and sodium pump activity in the thoracic aortae were measured in virgin and pregnant Sprague-Dawley rats without and with NaCl supplementation (drinking 1.8% NaCl solution). RESULTS NaCl supplementation of virgin rats stimulated renal excretion of MBG by 60%, but not that of EO, and did not change the BP. Compared with virgin rats, the last week of pregnancy in non-NaCl-loaded rats was associated with a decrease in SBP (106 +/- 2 versus 117 +/- 2 mmHg); a moderate increase in renal excretion of MBG (97.6 +/- 4.9 versus 57.4 +/- 7.0 pmoles/24 h) and EO (36.2 +/- 4.3 versus 24.1 +/- 3.2 pmoles/24 h). NaCl-loaded pregnant rats exhibited elevation in SBP (139 +/- 3 mmHg; P < 0.01 versus non-NaCl-loaded pregnant rats), in renal excretion of MBG (160.0 +/- 17.5 pmoles/24 h; P < 0.01 versus non-NaCl-loaded pregnant rats), but not in EO, and showed fetal growth retardation. Administration of the anti-MBG antibody to NaCl-loaded pregnant rats lowered SBP (111 +/- 2 mmHg; P < 0.01) and increased aortic sodium pump activity (144 +/- 3 versus 113 +/- 5 nmol Rb/g per min; P < 0.01 versus non-NaCl-loaded pregnant rats). CONCLUSIONS These observations provide evidence that MBG contributes to BP elevation in pregnant rats rendered hypertensive by NaCl supplementation.
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Affiliation(s)
- Olga V Fedorova
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore Maryland, USA
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Bagrov AY, Bagrov YY, Fedorova OV, Kashkin VA, Patkina NA, Zvartau EE. Endogenous digitalis-like ligands of the sodium pump: possible involvement in mood control and ethanol addiction. Eur Neuropsychopharmacol 2002; 12:1-12. [PMID: 11788235 DOI: 10.1016/s0924-977x(01)00127-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
This review addresses possible involvement of endogenous digitalis-like sodium pump ligands (SPL) in the mood control and ethanol addiction. Endogenous SPL include cardenolide and bufadienolide classes. Multiple SPL and multiple isoforms of the Na/K-ATPase, one of the key membrane enzymes, comprise a complex regulatory system. In the nervous system, pattern of expression of Na/K-ATPase is based on multiple alpha/beta isoform combinations. Clinical studies demonstrate changes in the activity of Na/K-ATPase in patients with bipolar and unipolar mood disorders. The effects of ethanol on the Na/K-ATPase are concentration-dependent and are associated with both inhibition and activation of enzyme activity. Reinforcing effect of ethanol as well as its voluntary consumption may be affected by digitalis glycosides and endogenous SPL.
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Affiliation(s)
- Alexei Y Bagrov
- Laboratories of Membrane Barrier Functions and Pharmacology, Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, 194223, Russia
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