1
|
Blaustein MP, Hamlyn JM. Sensational site: the sodium pump ouabain-binding site and its ligands. Am J Physiol Cell Physiol 2024; 326:C1120-C1177. [PMID: 38223926 PMCID: PMC11193536 DOI: 10.1152/ajpcell.00273.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 12/22/2023] [Accepted: 01/10/2024] [Indexed: 01/16/2024]
Abstract
Cardiotonic steroids (CTS), used by certain insects, toads, and rats for protection from predators, became, thanks to Withering's trailblazing 1785 monograph, the mainstay of heart failure (HF) therapy. In the 1950s and 1960s, we learned that the CTS receptor was part of the sodium pump (NKA) and that the Na+/Ca2+ exchanger was critical for the acute cardiotonic effect of digoxin- and ouabain-related CTS. This "settled" view was upended by seven revolutionary observations. First, subnanomolar ouabain sometimes stimulates NKA while higher concentrations are invariably inhibitory. Second, endogenous ouabain (EO) was discovered in the human circulation. Third, in the DIG clinical trial, digoxin only marginally improved outcomes in patients with HF. Fourth, cloning of NKA in 1985 revealed multiple NKA α and β subunit isoforms that, in the rodent, differ in their sensitivities to CTS. Fifth, the NKA is a cation pump and a hormone receptor/signal transducer. EO binding to NKA activates, in a ligand- and cell-specific manner, several protein kinase and Ca2+-dependent signaling cascades that have widespread physiological effects and can contribute to hypertension and HF pathogenesis. Sixth, all CTS are not equivalent, e.g., ouabain induces hypertension in rodents while digoxin is antihypertensinogenic ("biased signaling"). Seventh, most common rodent hypertension models require a highly ouabain-sensitive α2 NKA and the elevated blood pressure is alleviated by EO immunoneutralization. These numerous phenomena are enabled by NKA's intricate structure. We have just begun to understand the endocrine role of the endogenous ligands and the broad impact of the ouabain-binding site on physiology and pathophysiology.
Collapse
Affiliation(s)
- Mordecai P Blaustein
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States
| | - John M Hamlyn
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States
| |
Collapse
|
2
|
Socha MW, Chmielewski J, Pietrus M, Wartęga M. Endogenous Digitalis-like Factors as a Key Molecule in the Pathophysiology of Pregnancy-Induced Hypertension and a Potential Therapeutic Target in Preeclampsia. Int J Mol Sci 2023; 24:12743. [PMID: 37628922 PMCID: PMC10454430 DOI: 10.3390/ijms241612743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 08/10/2023] [Accepted: 08/11/2023] [Indexed: 08/27/2023] Open
Abstract
Preeclampsia (PE), the most severe presentation of hypertensive disorders of pregnancy, is the major cause of morbidity and mortality linked to pregnancy, affecting both mother and fetus. Despite advances in prophylaxis and managing PE, delivery of the fetus remains the only causative treatment available. Focus on complex pathophysiology brought the potential for new treatment options, and more conservative options allowing reduction of feto-maternal complications and sequelae are being investigated. Endogenous digitalis-like factors, which have been linked to the pathogenesis of preeclampsia since the mid-1980s, have been shown to play a role in the pathogenesis of various cardiovascular diseases, including congestive heart failure and chronic renal disease. Elevated levels of EDLF have been described in pregnancy complicated by hypertensive disorders and are currently being investigated as a therapeutic target in the context of a possible breakthrough in managing preeclampsia. This review summarizes mechanisms implicating EDLFs in the pathogenesis of preeclampsia and evidence for their potential role in treating this doubly life-threatening disease.
Collapse
Affiliation(s)
- Maciej W. Socha
- Department of Perinatology, Gynecology and Gynecologic Oncology, Faculty of Health Sciences, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Łukasiewicza 1, 85-821 Bydgoszcz, Poland
- Department of Obstetrics and Gynecology, St. Adalbert’s Hospital in Gdańsk, Copernicus Healthcare Entity, Jana Pawła II 50, 80-462 Gdańsk, Poland
| | - Jakub Chmielewski
- Department of Obstetrics and Gynecology, St. Adalbert’s Hospital in Gdańsk, Copernicus Healthcare Entity, Jana Pawła II 50, 80-462 Gdańsk, Poland
| | - Miłosz Pietrus
- Department of Gynecology and Obstetrics, Jagiellonian University Medical College, 31-501 Kraków, Poland
| | - Mateusz Wartęga
- Department of Pathophysiology, Faculty of Pharmacy, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, M. Curie- Skłodowskiej 9, 85-094 Bydgoszcz, Poland
| |
Collapse
|
3
|
Carullo N, Fabiano G, D'Agostino M, Zicarelli MT, Musolino M, Presta P, Michael A, Andreucci M, Bolignano D, Coppolino G. New Insights on the Role of Marinobufagenin from Bench to Bedside in Cardiovascular and Kidney Diseases. Int J Mol Sci 2023; 24:11186. [PMID: 37446363 DOI: 10.3390/ijms241311186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 07/03/2023] [Accepted: 07/04/2023] [Indexed: 07/15/2023] Open
Abstract
Marinobufagenin (MBG) is a member of the bufadienolide family of compounds, which are natural cardiac glycosides found in a variety of animal species, including man, which have different physiological and biochemical functions but have a common action on the inhibition of the adenosine triphosphatase sodium-potassium pump (Na+/K+-ATPase). MBG acts as an endogenous cardiotonic steroid, and in the last decade, its role as a pathogenic factor in various human diseases has emerged. In this paper, we have collated major evidence regarding the biological characteristics and functions of MBG and its implications in human pathology. This review focused on MBG involvement in chronic kidney disease, including end-stage renal disease, cardiovascular diseases, sex and gender medicine, and its actions on the nervous and immune systems. The role of MBG in pathogenesis and the development of a wide range of pathological conditions indicate that this endogenous peptide could be used in the future as a diagnostic biomarker and/or therapeutic target, opening important avenues of scientific research.
Collapse
Affiliation(s)
- Nazareno Carullo
- Renal Unit, "Magna Graecia" University of Catanzaro, 88100 Catanzaro, Italy
| | - Giuseppe Fabiano
- Renal Unit, "Magna Graecia" University of Catanzaro, 88100 Catanzaro, Italy
| | - Mario D'Agostino
- Renal Unit, "Magna Graecia" University of Catanzaro, 88100 Catanzaro, Italy
| | | | - Michela Musolino
- Renal Unit, "Magna Graecia" University of Catanzaro, 88100 Catanzaro, Italy
| | - Pierangela Presta
- Renal Unit, "Magna Graecia" University of Catanzaro, 88100 Catanzaro, Italy
| | - Ashour Michael
- Renal Unit, "Magna Graecia" University of Catanzaro, 88100 Catanzaro, Italy
| | - Michele Andreucci
- Renal Unit, "Magna Graecia" University of Catanzaro, 88100 Catanzaro, Italy
| | - Davide Bolignano
- Renal Unit, "Magna Graecia" University of Catanzaro, 88100 Catanzaro, Italy
| | - Giuseppe Coppolino
- Renal Unit, "Magna Graecia" University of Catanzaro, 88100 Catanzaro, Italy
| |
Collapse
|
4
|
Agalakova NI, Reznik VA, Ershov IA, Lupanova EA, Nadei OV, Ivanov DO, David Adair C, Bagrov AY. Silencing of Fli1 Gene Mimics Effects of Preeclampsia and Induces Collagen Synthesis in Human Umbilical Arteries. Am J Hypertens 2022; 35:828-832. [PMID: 35569064 DOI: 10.1093/ajh/hpac065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 02/27/2022] [Accepted: 05/13/2022] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Previously we demonstrated that in patients with preeclampsia elevated levels of endogenous Na/K-ATPase inhibitor, marinobufagenin, cause inhibition of Friend leukemia virus integration 1 (Fli1), a negative regulator of collagen-1 synthesis. We hypothesized that in vitro silencing of Fli1 in healthy human umbilical arteries would be associated with an increase in collagen-1 output, similar to the effect of preeclampsia in rat and human tissues. METHODS The isolated segments of healthy human umbilical arteries were tested for sensitivity to MBG and Fli1 silencing with Fli1 siRNA or control siRNA. RESULTS Following 24-hour incubation of arteries with nanomolar concentrations of marinobufagenin, Fli1 expression was inhibited 5-fold (P < 0.001), and synthesis of collagen-1 increased 3 times (P < 0.01). Twenty-four-hour incubation of umbilical artery fragments with Fli1 siRNA caused a dramatic decrease of Fli1 (7-fold; P < 0.001) and cytoplasmic PKC δ (4-fold; P < 0.001) expression in comparison to control siRNA or untreated control, followed by elevation in procollagen (3-fold; P < 0.001) and collagen-1 (3-fold; P < 0.001) levels in vascular tissue. CONCLUSIONS Our results show that after silencing the Fli1 gene in healthy human umbilical arteries a new phenotype emerges which is typical for preeclampsia and is associated with vascular fibrosis.
Collapse
Affiliation(s)
- Natalia I Agalakova
- Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, Russia
| | - Vitaly A Reznik
- Department of Obstetrics and Gynecology, St. Petersburg State Pediatric Medical University, St. Petersburg, Russia
| | - Ivan A Ershov
- Department of Obstetrics and Gynecology, St. Petersburg State Pediatric Medical University, St. Petersburg, Russia
| | - Ekaterina A Lupanova
- Department of Obstetrics and Gynecology, St. Petersburg State Pediatric Medical University, St. Petersburg, Russia
| | - Olga V Nadei
- Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, Russia
| | - Dmitry O Ivanov
- Department of Obstetrics and Gynecology, St. Petersburg State Pediatric Medical University, St. Petersburg, Russia
| | - C David Adair
- Department of Obstetrics and Gynecology, Section on Maternal Fetal Medicine, University of Tennessee, Chattanooga, Tennessee, USA
| | - Alexei Y Bagrov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, Russia
- Padakonn Pharma, Narva, Estonia
| |
Collapse
|
5
|
Canrenone Restores Vasorelaxation Impaired by Marinobufagenin in Human Preeclampsia. Int J Mol Sci 2022; 23:ijms23063336. [PMID: 35328757 PMCID: PMC8954517 DOI: 10.3390/ijms23063336] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/12/2022] [Accepted: 03/14/2022] [Indexed: 02/01/2023] Open
Abstract
Previous studies implicated cardiotonic steroids, including Na/K-ATPase inhibitor marinobufagenin (MBG), in the pathogenesis of preeclampsia (PE). Recently, we demonstrated that (i) MBG induces fibrosis in rat tissues via a mechanism involving Fli1, a negative regulator of collagen-1 synthesis, and (ii) MBG sensitive Na/K-ATPase inhibition is reversed by mineralocorticoid antagonists. We hypothesized that in human PE elevated MBG level is associated with the development of fibrosis of the umbilical arteries and that this fibrosis can be attenuated by canrenone. Fifteen patients with PE (mean BP = 118 ± 4 mmHg; 34 ± 2 years; 38 ± 0.3 weeks gest. age) and twelve gestational age-matched normal pregnant subjects (mean BP = 92 ± 2 mmHg; 34 ± 1 years; 39 ± 0.2 weeks gest. age) were enrolled in the study. PE was associated with a higher plasma MBG level, with a four-fold decrease in Fli1 level and a three-fold increase in collagen-1 level in the PE umbilical arteries vs. those from the normal subjects (p < 0.01). Isolated rings of umbilical arteries from the subjects with PE exhibited impaired responses to the relaxant effect of sodium nitroprusside vs. control vessels (EC50 = 141 nmol/L vs. EC50 = 0.9 nmol/L; p < 0.001). The effects of PE on Fli1 and collagen-1 were blocked by the in vitro treatment of umbilical arteries by 10 μmol/L canrenone. Similar results were obtained for umbilical arteries pretreated with MBG. These data demonstrate that elevated MBG level is implicated in the development of the fibrosis of umbilical arteries in PE, and that this could be blocked by mineralocorticoid antagonists.
Collapse
|
6
|
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.
Collapse
Affiliation(s)
| | | | | | - Grzegorz Piecha
- Correspondence: ; Tel.: +48-322-591-429; Fax: +48-322-553-726
| |
Collapse
|
7
|
Agalakova NI, Kolodkin NI, Adair CD, Trashkov AP, Bagrov AY. Preeclampsia: Cardiotonic Steroids, Fibrosis, Fli1 and Hint to Carcinogenesis. Int J Mol Sci 2021; 22:ijms22041941. [PMID: 33669287 PMCID: PMC7920043 DOI: 10.3390/ijms22041941] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 01/31/2021] [Accepted: 02/05/2021] [Indexed: 12/14/2022] Open
Abstract
Despite prophylaxis and attempts to select a therapy, the frequency of preeclampsia does not decrease and it still takes the leading position in the structure of maternal mortality and morbidity worldwide. In this review, we present a new theory of the etiology and pathogenesis of preeclampsia that is based on the interaction of Na/K-ATPase and its endogenous ligands including marinobufagenin. The signaling pathway of marinobufagenin involves an inhibition of transcriptional factor Fli1, a negative regulator of collagen synthesis, followed by the deposition of collagen in the vascular tissues and altered vascular functions. Moreover, in vitro and in vivo neutralization of marinobufagenin is associated with the restoration of Fli1. The inverse relationship between marinobufagenin and Fli1 opens new possibilities in the treatment of cancer; as Fli1 is a proto-oncogene, a hypothesis on the suppression of Fli1 by cardiotonic steroids as a potential anti-tumor therapeutic strategy is discussed as well. We propose a novel therapy of preeclampsia that is based on immunoneutralization of the marinobufagenin by monoclonal antibodies, which is capable of impairing marinobufagenin-Na/K-ATPase interactions.
Collapse
Affiliation(s)
- Natalia I. Agalakova
- Sechenov Institute of Evolutionary Physiology and Biochemistry, 44 Torez Prospect, 194223 St. Petersburg, Russia;
| | - Nikolai I. Kolodkin
- State Institute of Highly Pure Biopreparations and Sechenov Institute of Evolutionary Physiology and Biochemistry, 44 Torez Prospect, 194223 St. Petersburg, Russia; or
| | - C. David Adair
- Department of Obstetrics and Gynecology, University of Tennessee, Chattanooga, TN 37402, USA; or
| | - Alexander P. Trashkov
- Konstantinov St. Petersburg Nuclear Physics Institute, National Research Centre Kurchatov Institute, 1 Orlova Roshcha, 188300 Gatchina, Russia;
| | - Alexei Y. Bagrov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, 44 Torez Prospect, 194223 St. Petersburg, Russia;
- Correspondence:
| |
Collapse
|
8
|
Cardiotonic Steroids Induce Vascular Fibrosis Via Pressure-Independent Mechanism in NaCl-Loaded Diabetic Rats. J Cardiovasc Pharmacol 2020; 74:436-442. [PMID: 31415452 DOI: 10.1097/fjc.0000000000000730] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Endogenous cardiotonic steroid, marinobufagenin (MBG), induces Fli1-dependent tissue fibrosis. We hypothesized that an increase in MBG initiates the development of aortic fibrosis in salt-loaded rats with type 2 diabetes mellitus (DM2) via pressure-independent mechanism. DM2 was induced by a single intraperitoneal administration of 65 mg/kg streptozotocin to neonatal (4-5 days) male Wistar rats. Eight-week-old DM2 rats received water or 1.8% NaCl (DM-NaCl) solution for 4 weeks (n = 16); half of DM-NaCl rats were treated with anti-MBG monoclonal antibody (mAb) (DM-NaCl-AB) during week 4 of salt loading; control intact rats received water (n = 8/group). Blood pressure, MBG, erythrocyte Na/K-ATPase activity, aortic weights, levels of fibrosis markers (Fli1, protein kinase Cδ, transforming growth factor-β1, receptors of the transforming growth factor beta5, fibronectin, collagen-1), and sensitivity of the aortic explants to the vasorelaxant effect of sodium nitroprusside were assessed. No changes in systolic blood pressure were observed while erythrocyte Na/K-ATPase was inhibited by 30%, plasma MBG was doubled, and aortic markers of fibrosis became elevated in DM-NaCl rats versus control. Treatment of DM-NaCl rats with anti-MBG mAb activated Na/K-ATPase, prevented increases in aortic weights, and the levels of fibrosis markers returned to the control levels. The responsiveness of the aortic rings from DM-NaCl rats to the relaxant effect of sodium nitroprusside was reduced (half maximal effective concentration (EC50) = 29 nmol/L) versus control rings (EC50 = 7 nmol/L) and was restored by anti-MBG mAb (EC50 = 9 nmol/L). Our results suggest that in salt-loaded diabetic rats, MBG stimulates aortic collagen synthesis in a pressure-independent fashion and that 2 profibrotic mechanisms, Fli1 dependent and transforming growth factor-β dependent, underlie its effects.
Collapse
|
9
|
Agalakova NI, Reznik VA, Nadei OV, Ershov IA, Rassokha OS, Vasyutina ML, Ivanov DO, Adair CD, Galagudza MM, Bagrov AY. Antibody against Na/K-ATPase Inhibitor Lowers Blood Pressure and Increases Vascular Fli1 in Experimental Preeclampsia. Am J Hypertens 2020; 33:514-519. [PMID: 31713584 DOI: 10.1093/ajh/hpz180] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/21/2019] [Accepted: 11/09/2019] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Previous studies implicated cardiotonic steroids, including Na/K-ATPase inhibitor marinobufagenin (MBG), in the pathogenesis of preeclampsia (PE). We demonstrated that MBG induces fibrosis via mechanism involving inhibition of Fli1, a nuclear transcription factor and a negative regulator of collagen-1 synthesis. We hypothesized that PE blockade of increased MBG with antibody would lessen the fibrosis of umbilical arteries and lower the blood pressure in rats with PE. METHODS We tested 36 pregnant Sprague-Dawley rats in which 12 were made hypertensive by 1.8% Na supplementation (days 6-19 of gestation), 12 pregnant rats served controls. At day 19, PE rats received one intraperitoneal injection of polyclonal anti-MBG-4 antibody (0.5 ug/ml) for 4 hours. RESULTS PE was associated with higher blood pressure (117 ± 2 vs. 107 ± 2 mm Hg; P < 0.01), plasma MBG levels (1.54 ± 0.34 vs. 0.49 ± 0.11 nmol/L; P < 0.01), protein excretion (26 vs. 12 mg/24 hours), sFlt-1 (3-fold), decrease in Fli1 (7-fold) and increase in collagen-1 in aorta (4-fold) vs. control rats (all P < 0.01). In 12 rats treated with polyclonal anti-MBG-4 antibody blood pressure dropped (93 ± 3 mm Hg) and Fli1 was decreased much less (2-fold; P < 0.01 vs. nontreated rats). CONCLUSIONS These results demonstrate that in experimental PE elevated MBG level is implicated in umbilical fibrosis via suppression of Fli1.
Collapse
Affiliation(s)
- Natalia I Agalakova
- Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, Russia
| | - Vitaly A Reznik
- Department of Obstetrics and Gynecology, St. Petersburg State Pediatric Medical University, St. Petersburg, Russia
| | - Olga V Nadei
- Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, Russia
| | - Ivan A Ershov
- Department of Obstetrics and Gynecology, St. Petersburg State Pediatric Medical University, St. Petersburg, Russia
| | - Olga S Rassokha
- Department of Obstetrics and Gynecology, St. Petersburg State Pediatric Medical University, St. Petersburg, Russia
| | - Marina L Vasyutina
- Institute of Experimental Medicine, Almazov National Medical Research Centre, St. Petersburg, Russia
| | - Dmitry O Ivanov
- Department of Obstetrics and Gynecology, St. Petersburg State Pediatric Medical University, St. Petersburg, Russia
| | - C David Adair
- Department of Obstetrics and Gynecology, University of Tennessee, Chattanooga, Tennessee, USA
| | - Michael M Galagudza
- Institute of Experimental Medicine, Almazov National Medical Research Centre, St. Petersburg, Russia
| | - Alexei Y Bagrov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, Russia
| |
Collapse
|
10
|
Buckalew VM. Is Preeclampsia a Profibrotic Condition? Am J Hypertens 2020; 33:491-492. [PMID: 32140701 DOI: 10.1093/ajh/hpaa033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 01/07/2020] [Accepted: 02/28/2020] [Indexed: 11/14/2022] Open
Affiliation(s)
- Vardaman M Buckalew
- Emeritus Professor of Medicine, Section of Nephrology, Wake Forest University School of Medicine, Winston Salem, NC, USA
| |
Collapse
|
11
|
Orlov SN, Tverskoi AM, Sidorenko SV, Smolyaninova LV, Lopina OD, Dulin NO, Klimanova EA. Na,K-ATPase as a target for endogenous cardiotonic steroids: What's the evidence? Genes Dis 2020; 8:259-271. [PMID: 33997173 PMCID: PMC8093582 DOI: 10.1016/j.gendis.2020.01.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/24/2019] [Accepted: 01/09/2020] [Indexed: 12/17/2022] Open
Abstract
With an exception of few reports, the plasma concentration of ouabain and marinobufagenin, mostly studied cardiotonic steroids (CTS) assessed by immunoassay techniques, is less than 1 nM. During the last 3 decades, the implication of these endogenous CTS in the pathogenesis of hypertension and other volume-expanded disorders is widely disputed. The threshold for inhibition by CTS of human and rodent α1-Na,K-ATPase is ∼1 and 1000 nM, respectively, that rules out the functioning of endogenous CTS (ECTS) as natriuretic hormones and regulators of cell adhesion, cell-to-cell communication, gene transcription and translation, which are mediated by dissipation of the transmembrane gradients of monovalent cations. In several types of cells ouabain and marinobufagenin at concentrations corresponding to its plasma level activate Na,K-ATPase, decrease the [Na+]i/[K+]i-ratio and increase cell proliferation. Possible physiological significance and mechanism of non-canonical Na+i/K+i-dependent and Na+i/K+i-independent cell responses to CTS are discussed.
Collapse
Affiliation(s)
- Sergei N Orlov
- MV Lomonosov Moscow State University, Moscow, 119234, Russia.,National Research Tomsk State University, Tomsk, 634050, Russia.,Siberian State Medical University, Tomsk, 634050, Russia
| | | | - Svetlana V Sidorenko
- MV Lomonosov Moscow State University, Moscow, 119234, Russia.,National Research Tomsk State University, Tomsk, 634050, Russia
| | - Larisa V Smolyaninova
- MV Lomonosov Moscow State University, Moscow, 119234, Russia.,National Research Tomsk State University, Tomsk, 634050, Russia
| | - Olga D Lopina
- MV Lomonosov Moscow State University, Moscow, 119234, Russia
| | | | - Elizaveta A Klimanova
- MV Lomonosov Moscow State University, Moscow, 119234, Russia.,National Research Tomsk State University, Tomsk, 634050, Russia
| |
Collapse
|
12
|
Abstract
Frequency of preeclampsia has no tendency to decrease, and it still takes the leading position in the structure of maternal mortality and morbidity worldwide. In this review, we present the “fibrotic concept” of the etiology and pathogenesis of preeclampsia which involves system consisting of Na/K-ATPase and its endogenous ligands including marinobufagenin. New therapy of preeclampsia includes modulation of the Na/K-ATPase system by immunoneutralization of the marinobufagenin and use of mineralocorticoid antagonists which are capable to impair marinobufagenin-Na/K-ATPase interactions.
Collapse
|
13
|
Influence of Endogenous Cardiac Glycosides, Digoxin, and Marinobufagenin in the Physiology of Epithelial Cells. Cardiol Res Pract 2019; 2019:8646787. [PMID: 32089875 PMCID: PMC7024086 DOI: 10.1155/2019/8646787] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 09/20/2019] [Accepted: 11/15/2019] [Indexed: 12/14/2022] Open
Abstract
Cardiac glycosides are a group of compounds widely known for their action in cardiac tissue, some of which have been found to be endogenously produced (ECG). We have previously studied the effect of ouabain, an endogenous cardiac glycoside, on the physiology of epithelial cells, and we have shown that in concentrations in the nanomolar range, it affects key properties of epithelial cells, such as tight junction, apical basolateral polarization, gap junctional intercellular communication (GJIC), and adherent junctions. In this work, we study the influence of digoxin and marinobufagenin, two other endogenously expressed cardiac glycosides, on GJIC as well as the degree of transepithelial tightness due to tight junction integrity (TJ). We evaluated GJIC by dye transfer assays and tight junction integrity by transepithelial electrical resistance (TER) measurements, as well as immunohistochemistry and western blot assays of expression of claudins 2 and 4. We found that both digoxin and marinobufagenin improve GJIC and significantly enhance the tightness of the tight junctions, as evaluated from TER measurements. Immunofluorescence assays show that both compounds promote enhanced basolateral localization of claudin-4 but not claudin 2, while densitometric analysis of western blot assays indicate a significantly increased expression of claudin 4. These changes, induced by digoxin and marinobufagenin on GJIC and TER, were not observed on MDCK-R, a modified MDCK cell line that has a genetically induced insensitive α1 subunit, indicating that Na-K-ATPase acts as a receptor mediating the actions of both ECG. Plus, the fact that the effect of both cardiac glycosides was suppressed by incubation with PP2, an inhibitor of c-Src kinase, PD98059, an inhibitor of mitogen extracellular kinase-1 and Y-27632, a selective inhibitor of ROCK, and a Rho-associated protein kinase, indicate altogether that the signaling pathways involved include c-Src and ERK1/2, as well as Rho-ROCK. These results widen and strengthen our general hypothesis that a very important physiological role of ECG is the control of the epithelial phenotype and the regulation of cell-cell contacts.
Collapse
|
14
|
Pavlovic D. Endogenous cardiotonic steroids and cardiovascular disease, where to next? Cell Calcium 2019; 86:102156. [PMID: 31896530 PMCID: PMC7031694 DOI: 10.1016/j.ceca.2019.102156] [Citation(s) in RCA: 15] [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: 12/03/2019] [Revised: 12/24/2019] [Accepted: 12/24/2019] [Indexed: 11/18/2022]
Abstract
Ever since British Physician William Withering first described the use of foxglove extract for treatment of patients with congestive heart failure in 1785, cardiotonic steroids have been used clinically to treat heart failure and more recently atrial fibrillation. Due to their ability to bind and inhibit the ubiquitous transport enzyme sodium potassium pump, thus regulating intracellular Na+ concentration in every living cell, they are also an essential tool for research into the sodium potassium pump structure and function. Exogenous CTS have been clearly demonstrated to affect cardiovascular system through modulation of vagal tone, cardiac contraction (via ionic changes) and altered natriuresis. Reports of a number of endogenous CTS, since the 1980s, have intensified research into their physiologic and pathophysiologic roles and opened up novel therapeutic targets. Substantive evidence pointing to the role of endogenous ouabain and marinobufagenin, the two most prominent CTS, in development of cardiovascular disease has accumulated. Nevertheless, their presence, structure, biosynthesis pathways and even mechanism of action remain unclear or controversial. In this review the current state-of-the-art, the controversies and the remaining questions surrounding the role of endogenous cardiotonic steroids in health and disease are discussed.
Collapse
Affiliation(s)
- Davor Pavlovic
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
| |
Collapse
|
15
|
Zhang Y, Wei W, Shilova V, Petrashevskaya NN, Zernetkina VI, Grigorova YN, Marshall CA, Fenner RC, Lehrmann E, Wood WH, Becker KG, Lakatta EG, Bagrov AY, Fedorova OV. Monoclonal Antibody to Marinobufagenin Downregulates TGFβ Profibrotic Signaling in Left Ventricle and Kidney and Reduces Tissue Remodeling in Salt-Sensitive Hypertension. J Am Heart Assoc 2019; 8:e012138. [PMID: 31576777 PMCID: PMC6818028 DOI: 10.1161/jaha.119.012138] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Background Elevated levels of an endogenous Na/K-ATPase inhibitor marinobufagenin accompany salt-sensitive hypertension and are implicated in cardiac fibrosis. Immunoneutralization of marinobufagenin reduces blood pressure in Dahl salt-sensitive (Dahl-S) rats. The effect of the anti-marinobufagenin monoclonal antibody on blood pressure, left ventricular (LV) and renal remodeling, and gene expression were investigated in hypertensive Dahl-S rats. Methods and Results Dahl-S rats were fed high NaCl (8%, HS; n=14) or low NaCl (0.1%, LS; n=14) diets for 8 weeks. Animals were administered control antibody (LS control antibody, LSC; HS control antibody, HSC; n=7 per group) or anti-marinobufagenin antibody once on week 7 of diet intervention (n=7 per group). Levels of marinobufagenin, LV, and kidney mRNAs and proteins implicated in profibrotic signaling were assessed. Systolic blood pressure was elevated (211±8 versus 133±3 mm Hg, P<0.01), marinobufagenin increased 2-fold in plasma (P<0.05) and 5-fold in urine (P<0.01), LV and kidney weights increased, and levels of LV collagen-1 rose 3.5-fold in HSC versus LSC. Anti-marinobufagenin antibody treatment decreased systolic blood pressure by 24 mm Hg (P<0.01) and reduced organ weights and level of LV collagen-1 (P<0.01) in hypertensive Dahl salt-sensitive rats with anti-marinobufagenin antibody versus HSC. The expression of genes related to transforming growth factor-β-dependent signaling was upregulated in the left ventricles and kidneys in HSC versus LSC groups and became downregulated following administration of anti-marinobufagenin antibody to hypertensive Dahl-S rats. Marinobufagenin also activated transforming growth factor-β signaling in cultured ventricular myocytes from Dahl-S rats. Conclusions Immunoneutralization of heightened marinobufagenin levels in hypertensive Dahl-S rats resulted in a downregulation of genes implicated in transforming growth factor-β pathway, which indicates that marinobufagenin is an activator of profibrotic transforming growth factor-β-dependent signaling in salt-sensitive hypertension.
Collapse
Affiliation(s)
- Yongqing Zhang
- Laboratory of Genetics and Genomics National Institute on Aging NIH Baltimore MD
| | - Wen Wei
- Laboratory of Cardiovascular Science National Institute on Aging NIH Baltimore MD
| | - Victoria Shilova
- Laboratory of Cardiovascular Science National Institute on Aging NIH Baltimore MD
| | | | | | - Yulia N Grigorova
- Laboratory of Cardiovascular Science National Institute on Aging NIH Baltimore MD
| | - Courtney A Marshall
- Laboratory of Cardiovascular Science National Institute on Aging NIH Baltimore MD
| | - Rachel C Fenner
- Laboratory of Cardiovascular Science National Institute on Aging NIH Baltimore MD
| | - Elin Lehrmann
- Laboratory of Genetics and Genomics National Institute on Aging NIH Baltimore MD
| | - William H Wood
- Laboratory of Genetics and Genomics National Institute on Aging NIH Baltimore MD
| | - Kevin G Becker
- Laboratory of Genetics and Genomics National Institute on Aging NIH Baltimore MD
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science National Institute on Aging NIH Baltimore MD
| | - Alexei Y Bagrov
- Laboratory of Cardiovascular Science National Institute on Aging NIH Baltimore MD
| | - Olga V Fedorova
- Laboratory of Cardiovascular Science National Institute on Aging NIH Baltimore MD
| |
Collapse
|
16
|
Vilchis-Nestor CA, Roldán ML, Leonardi A, Navea JG, Padilla-Benavides T, Shoshani L. Ouabain Enhances Cell-Cell Adhesion Mediated by β 1 Subunits of the Na +,K +-ATPase in CHO Fibroblasts. Int J Mol Sci 2019; 20:E2111. [PMID: 31035668 PMCID: PMC6539428 DOI: 10.3390/ijms20092111] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 04/26/2019] [Accepted: 04/26/2019] [Indexed: 12/19/2022] Open
Abstract
Adhesion is a crucial characteristic of epithelial cells to form barriers to pathogens and toxic substances from the environment. Epithelial cells attach to each other using intercellular junctions on the lateral membrane, including tight and adherent junctions, as well as the Na+,K+-ATPase. Our group has shown that non-adherent chinese hamster ovary (CHO) cells transfected with the canine β1 subunit become adhesive, and those homotypic interactions amongst β1 subunits of the Na+,K+-ATPase occur between neighboring epithelial cells. Ouabain, a cardiotonic steroid, binds to the α subunit of the Na+,K+-ATPase, inhibits the pump activity and induces the detachment of epithelial cells when used at concentrations above 300 nM. At nanomolar non-inhibiting concentrations, ouabain affects the adhesive properties of epithelial cells by inducing the expression of cell adhesion molecules through the activation of signaling pathways associated with the α subunit. In this study, we investigated whether the adhesion between β1 subunits was also affected by ouabain. We used CHO fibroblasts stably expressing the β1 subunit of the Na+,K+-ATPase (CHO β1), and studied the effect of ouabain on cell adhesion. Aggregation assays showed that ouabain increased the adhesion between CHO β1 cells. Immunofluorescence and biotinylation assays showed that ouabain (50 nM) increases the expression of the β1 subunit of the Na+,K+-ATPase at the cell membrane. We also examined the effect of ouabain on the activation of signaling pathways in CHO β1 cells, and their subsequent effect on cell adhesion. We found that cSrc is activated by ouabain and, therefore, that it likely regulates the adhesive properties of CHO β1 cells. Collectively, our findings suggest that the β1 subunit adhesion is modulated by the expression levels of the Na+,K+-ATPase at the plasma membrane, which is regulated by ouabain.
Collapse
Affiliation(s)
- Claudia Andrea Vilchis-Nestor
- Department of Physiology Biophysics and Neurosciences, Center for Research and Advanced Studies, Cinvestav-Ipn, CDMX 07360, Mexico.
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - María Luisa Roldán
- Department of Physiology Biophysics and Neurosciences, Center for Research and Advanced Studies, Cinvestav-Ipn, CDMX 07360, Mexico.
| | - Angelina Leonardi
- Department of Chemistry, Skidmore College, 815 North Broadway, Saratoga Springs, NY 12866, USA.
| | - Juan G Navea
- Department of Chemistry, Skidmore College, 815 North Broadway, Saratoga Springs, NY 12866, USA.
| | - Teresita Padilla-Benavides
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - Liora Shoshani
- Department of Physiology Biophysics and Neurosciences, Center for Research and Advanced Studies, Cinvestav-Ipn, CDMX 07360, Mexico.
| |
Collapse
|
17
|
Strauss M, Smith W, Fedorova OV, Schutte AE. The Na +K +-ATPase Inhibitor Marinobufagenin and Early Cardiovascular Risk in Humans: a Review of Recent Evidence. Curr Hypertens Rep 2019; 21:38. [PMID: 30980225 PMCID: PMC6590998 DOI: 10.1007/s11906-019-0942-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE OF REVIEW This review synthesizes recent findings in humans pertaining to the relationships between marinobufagenin (MBG), a steroidal Na+/K+-ATPase inhibitor and salt-sensitivity biomarker, and early cardiovascular risk markers. RECENT FINDINGS Twenty-four-hour urinary MBG strongly associates with habitual salt intake in young healthy adults (aged 20-30 years). Furthermore, in young healthy adults free of detected cardiovascular disease, MBG associates with increased large artery stiffness and left ventricular mass independent of blood pressure. These findings in human studies corroborate mechanistic data from rat studies whereby stimulation of MBG by a high salt intake or MBG infusion increased vascular fibrosis and cardiac hypertrophy. Twenty-four-hour urinary MBG may be a potential biomarker of early cardiovascular risk. Adverse associations between MBG-which increases with salt consumption-and early cardiovascular risk markers support the global efforts to reduce population-wide salt intake in an effort to prevent and control the burden of non-communicable diseases.
Collapse
Affiliation(s)
- Michél Strauss
- Hypertension in Africa Research Team (HART), North-West University, Private Bag X1290, Potchefstroom, 2520, South Africa
| | - Wayne Smith
- Hypertension in Africa Research Team (HART), North-West University, Private Bag X1290, Potchefstroom, 2520, South Africa
- MRC Research Unit: Hypertension and Cardiovascular Disease, North-West University, Potchefstroom, South Africa
| | - Olga V Fedorova
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD, USA
| | - Aletta E Schutte
- Hypertension in Africa Research Team (HART), North-West University, Private Bag X1290, Potchefstroom, 2520, South Africa.
- MRC Research Unit: Hypertension and Cardiovascular Disease, North-West University, Potchefstroom, South Africa.
| |
Collapse
|
18
|
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.
Collapse
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.
| |
Collapse
|
19
|
Kennedy DJ, Khalaf FK, Sheehy B, Weber ME, Agatisa-Boyle B, Conic J, Hauser K, Medert CM, Westfall K, Bucur P, Fedorova OV, Bagrov AY, Tang WHW. Telocinobufagin, a Novel Cardiotonic Steroid, Promotes Renal Fibrosis via Na⁺/K⁺-ATPase Profibrotic Signaling Pathways. Int J Mol Sci 2018; 19:ijms19092566. [PMID: 30158457 PMCID: PMC6164831 DOI: 10.3390/ijms19092566] [Citation(s) in RCA: 18] [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: 08/09/2018] [Revised: 08/26/2018] [Accepted: 08/27/2018] [Indexed: 12/24/2022] Open
Abstract
Cardiotonic steroids (CTS) are Na+/K+-ATPase (NKA) ligands that are elevated in volume-expanded states and associated with cardiac and renal dysfunction in both clinical and experimental settings. We test the hypothesis that the CTS telocinobufagin (TCB) promotes renal dysfunction in a process involving signaling through the NKA α-1 in the following studies. First, we infuse TCB (4 weeks at 0.1 µg/g/day) or a vehicle into mice expressing wild-type (WT) NKA α-1, as well as mice with a genetic reduction (~40%) of NKA α-1 (NKA α-1+/−). Continuous TCB infusion results in increased proteinuria and cystatin C in WT mice which are significantly attenuated in NKA α-1+/− mice (all p < 0.05), despite similar increases in blood pressure. In a series of in vitro experiments, 24-h treatment of HK2 renal proximal tubular cells with TCB results in significant dose-dependent increases in both Collagens 1 and 3 mRNA (2-fold increases at 10 nM, 5-fold increases at 100 nM, p < 0.05). Similar effects are seen in primary human renal mesangial cells. TCB treatment (100 nM) of SYF fibroblasts reconstituted with cSrc results in a 1.5-fold increase in Collagens 1 and 3 mRNA (p < 0.05), as well as increases in both Transforming Growth factor beta (TGFb, 1.5 fold, p < 0.05) and Connective Tissue Growth Factor (CTGF, 2 fold, p < 0.05), while these effects are absent in SYF cells without Src kinase. In a patient study of subjects with chronic kidney disease, TCB is elevated compared to healthy volunteers. These studies suggest that the pro-fibrotic effects of TCB in the kidney are mediated though the NKA-Src kinase signaling pathway and may have relevance to volume-overloaded conditions, such as chronic kidney disease where TCB is elevated.
Collapse
Affiliation(s)
- David J Kennedy
- Department of Medicine, University of Toledo College of Medicine, Toledo, OH 43614, USA.
| | - Fatimah K Khalaf
- Department of Medicine, University of Toledo College of Medicine, Toledo, OH 43614, USA.
| | - Brendan Sheehy
- Department of Cellular and Molecular Medicine, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44106, USA.
| | - Malory E Weber
- Department of Cellular and Molecular Medicine, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44106, USA.
| | - Brendan Agatisa-Boyle
- Department of Cellular and Molecular Medicine, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44106, USA.
| | - Julijana Conic
- Department of Cellular and Molecular Medicine, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44106, USA.
| | - Kayla Hauser
- Department of Cellular and Molecular Medicine, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44106, USA.
| | - Charles M Medert
- Department of Cellular and Molecular Medicine, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44106, USA.
| | - Kristen Westfall
- Department of Cellular and Molecular Medicine, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44106, USA.
| | - Philip Bucur
- Department of Cellular and Molecular Medicine, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44106, USA.
| | - Olga V Fedorova
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
| | - Alexei Y Bagrov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg 194223, Russia.
| | - W H Wilson Tang
- Department of Cellular and Molecular Medicine, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44106, USA.
- Center for Cardiovascular Diagnostics and Prevention, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44106, USA.
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
| |
Collapse
|
20
|
Fedorova OV, Ishkaraeva VV, Grigorova YN, Reznik VA, Kolodkin NI, Zazerskaya IE, Zernetkina V, Agalakova NI, Tapilskaya NI, Adair CD, Lakatta EG, Bagrov AY. Antibody to Marinobufagenin Reverses Placenta-Induced Fibrosis of Umbilical Arteries in Preeclampsia. Int J Mol Sci 2018; 19:ijms19082377. [PMID: 30104471 PMCID: PMC6121256 DOI: 10.3390/ijms19082377] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 08/04/2018] [Accepted: 08/07/2018] [Indexed: 02/01/2023] Open
Abstract
Background: Previous studies implicated cardiotonic steroids, including Na/K-ATPase inhibitor marinobufagenin (MBG), in the pathogenesis of preeclampsia (PE). Immunoneutralization of heightened MBG by Digibind, a digoxin antibody, reduces blood pressure (BP) in patients with PE, and anti-MBG monoclonal antibody lessens BP in a rat model of PE. Recently, we demonstrated that MBG induces fibrosis in cardiovascular tissues via a mechanism involving inhibition of Fli-1, a nuclear transcription factor and a negative regulator of collagen-1 synthesis. Objectives and Methods: We hypothesized that in PE, elevated placental MBG levels are associated with development of fibrosis in umbilical arteries. Eleven patients with PE (mean BP 124 ± 4 mmHg; age 29 ± 2 years; 39 weeks gest. age) and 10 gestational age-matched normal pregnant subjects (mean BP 92 ± 2 mmHg; controls) were enrolled in the clinical study. Results: PE was associated with a higher placental (0.04 ± 0.01 vs. 0.49 ± 0.11 pmol/g; p < 0.01) and plasma MBG (0.5 ± 0.1 vs. 1.6 ± 0.5 nmol/L; p < 0.01), lower Na/K-ATPase activity in erythrocytes (2.7 ± 0.2 vs. 1.5 ± 0.2 µmol Pi/mL/hr; p < 0.01), 9-fold decrease of Fli-1 level and 2.5-fold increase of collagen-1 in placentae (p < 0.01) vs. control. Incubation of umbilical arteries from control patients with 1 nmol/L MBG was associated with four-fold decrease in Fli-1 level and two-fold increase in collagen-1 level vs. those incubated with placebo (p < 0.01), i.e., physiological concentration of MBG mimicked effect of PE in vitro. Collagen-1 abundance in umbilical arteries from PE patients was 4-fold higher than in control arteries, and this PE-associated fibrosis was reversed by monoclonal anti-MBG antibody ex vivo. Conclusion: These results demonstrate that elevated placental MBG level is implicated in the development of fibrosis of the placenta and umbilical arteries in PE.
Collapse
Affiliation(s)
- Olga V Fedorova
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA.
| | - Valentina V Ishkaraeva
- Institute of Neonatology, Almazov Federal Heart, Blood and Endocrinology Center, St. Petersburg 197431, Russia.
| | - Yulia N Grigorova
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA.
| | - Vitaly A Reznik
- Department of Obstetrics and Gynecology, School of Pediatric Medicine, St. Petersburg 194353, Russia.
| | - Nikolai I Kolodkin
- Institute of Highly Pure Biopreparations, St. Petersburg 197110, Russia.
- Sechenov Institute of Evolutionary Physiology and Biochemistry, 44 Torez Prospect, St. Petersburg 194223, Russia.
| | - Irina E Zazerskaya
- Institute of Neonatology, Almazov Federal Heart, Blood and Endocrinology Center, St. Petersburg 197431, Russia.
| | - Valentina Zernetkina
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA.
| | - Natalia I Agalakova
- Sechenov Institute of Evolutionary Physiology and Biochemistry, 44 Torez Prospect, St. Petersburg 194223, Russia.
| | | | - C David Adair
- Department of Obstetrics and Gynecology, University of Tennessee, Chattanooga, TN 37403, USA.
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, National Institute on Aging, NIH, Baltimore, MD 21224, USA.
| | - Alexei Y Bagrov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, 44 Torez Prospect, St. Petersburg 194223, Russia.
| |
Collapse
|
21
|
Endogenous Ouabain and Related Genes in the Translation from Hypertension to Renal Diseases. Int J Mol Sci 2018; 19:ijms19071948. [PMID: 29970843 PMCID: PMC6073363 DOI: 10.3390/ijms19071948] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 06/28/2018] [Accepted: 06/29/2018] [Indexed: 01/22/2023] Open
Abstract
The endogenous ouabain (EO) is a steroid hormone secreted by the adrenal gland with cardio-tonic effects. In this article, we have reviewed and summarized the most recent reports about EO, particularly with regard to how it may interact with specific genetic backgrounds. We have focused our attention on the EO’s potential pathogenic role in several diseases, including renal failure, essential hypertension and heart failure. Notably, these reports have demonstrated that EO acts as a pro-hypertrophic and growth-promoting hormone, which might lead to a cardiac remodeling affecting cardiovascular functions and structures. In addition, a possible role of EO in the development of acute kidney injury has been hypothesized. During the last decays, many important improvements permitted a deeper understanding of EO’s metabolisms and functions, including the characteristics of its receptor and the effects of its activation. Such progresses indicated that EO has significant implications in the pathogenesis of many common diseases. The patho-physiological role of EO in the development of hypertension and other cardiac and renal complications have laid the basis for the development of a new selective compound that could selectively modulate the genetic and molecular mechanisms involved in EO’s action. It is evident that the knowledge of EO has incredibly increased; however, many important areas remain to be further investigated.
Collapse
|
22
|
Na⁺ i,K⁺ i-Dependent and -Independent Signaling Triggered by Cardiotonic Steroids: Facts and Artifacts. Molecules 2017; 22:molecules22040635. [PMID: 28420099 PMCID: PMC6153942 DOI: 10.3390/molecules22040635] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 03/31/2017] [Accepted: 04/11/2017] [Indexed: 11/17/2022] Open
Abstract
Na⁺,K⁺-ATPase is the only known receptor of cardiotonic steroids (CTS) whose interaction with catalytic α-subunits leads to inhibition of this enzyme. As predicted, CTS affect numerous cellular functions related to the maintenance of the transmembrane gradient of monovalent cations, such as electrical membrane potential, cell volume, transepithelial movement of salt and osmotically-obliged water, symport of Na⁺ with inorganic phosphate, glucose, amino acids, nucleotides, etc. During the last two decades, it was shown that side-by-side with these canonical Na⁺i/K⁺i-dependent cellular responses, long-term exposure to CTS affects transcription, translation, tight junction, cell adhesion and exhibits tissue-specific impact on cell survival and death. It was also shown that CTS trigger diverse signaling cascades via conformational transitions of the Na⁺,K⁺-ATPase α-subunit that, in turn, results in the activation of membrane-associated non-receptor tyrosine kinase Src, phosphatidylinositol 3-kinase and the inositol 1,4,5-triphosphate receptor. These findings allowed researchers to propose that endogenous CTS might be considered as a novel class of steroid hormones. We focus our review on the analysis of the relative impact Na⁺i,K⁺i-mediated and -independent pathways in cellular responses evoked by CTS.
Collapse
|
23
|
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.
Collapse
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.
| |
Collapse
|
24
|
Haller ST, Yan Y, Drummond CA, Xie J, Tian J, Kennedy DJ, Shilova VY, Xie Z, Liu J, Cooper CJ, Malhotra D, Shapiro JI, Fedorova OV, Bagrov AY. Rapamycin Attenuates Cardiac Fibrosis in Experimental Uremic Cardiomyopathy by Reducing Marinobufagenin Levels and Inhibiting Downstream Pro-Fibrotic Signaling. J Am Heart Assoc 2016; 5:JAHA.116.004106. [PMID: 27694325 PMCID: PMC5121507 DOI: 10.1161/jaha.116.004106] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Experimental uremic cardiomyopathy causes cardiac fibrosis and is causally related to the increased circulating levels of the cardiotonic steroid, marinobufagenin (MBG), which signals through Na/K-ATPase. Rapamycin is an inhibitor of the serine/threonine kinase mammalian target of rapamycin (mTOR) implicated in the progression of many different forms of renal disease. Given that Na/K-ATPase signaling is known to stimulate the mTOR system, we speculated that the ameliorative effects of rapamycin might influence this pathway. METHODS AND RESULTS Biosynthesis of MBG by cultured human JEG-3 cells is initiated by CYP27A1, which is also a target for rapamycin. It was demonstrated that 1 μmol/L of rapamycin inhibited production of MBG in human JEG-2 cells. Male Sprague-Dawley rats were subjected to either partial nephrectomy (PNx), infusion of MBG, and/or infusion of rapamycin through osmotic minipumps. PNx animals showed marked increase in plasma MBG levels (1025±60 vs 377±53 pmol/L; P<0.01), systolic blood pressure (169±1 vs 111±1 mm Hg; P<0.01), and cardiac fibrosis compared to controls. Plasma MBG levels were significantly decreased in PNx-rapamycin animals compared to PNx (373±46 vs 1025±60 pmol/L; P<0.01), and cardiac fibrosis was substantially attenuated by rapamycin treatment. CONCLUSIONS Rapamycin treatment in combination with MBG infusion significantly attenuated cardiac fibrosis. Our results suggest that rapamycin may have a dual effect on cardiac fibrosis through (1) mTOR inhibition and (2) inhibiting MBG-mediated profibrotic signaling and provide support for beneficial effect of a novel therapy for uremic cardiomyopathy.
Collapse
Affiliation(s)
- Steven T Haller
- University of Toledo College of Medicine and Life Sciences, Toledo, OH
| | - Yanling Yan
- Joan C. Edwards School of Medicine, Marshall University, Huntington, WV
| | | | - Joe Xie
- University of Toledo College of Medicine and Life Sciences, Toledo, OH
| | - Jiang Tian
- University of Toledo College of Medicine and Life Sciences, Toledo, OH
| | - David J Kennedy
- University of Toledo College of Medicine and Life Sciences, Toledo, OH
| | - Victoria Y Shilova
- Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, MD
| | - Zijian Xie
- Joan C. Edwards School of Medicine, Marshall University, Huntington, WV
| | - Jiang Liu
- Joan C. Edwards School of Medicine, Marshall University, Huntington, WV
| | | | - Deepak Malhotra
- University of Toledo College of Medicine and Life Sciences, Toledo, OH
| | - Joseph I Shapiro
- Joan C. Edwards School of Medicine, Marshall University, Huntington, WV
| | - Olga V Fedorova
- Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, MD
| | - Alexei Y Bagrov
- Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, MD
| |
Collapse
|
25
|
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.
Collapse
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
| | | | | | | | | | | |
Collapse
|
26
|
Pavlovic D. The role of cardiotonic steroids in the pathogenesis of cardiomyopathy in chronic kidney disease. Nephron Clin Pract 2014; 128:11-21. [PMID: 25341357 DOI: 10.1159/000363301] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Cardiotonic steroids (CTS) are a new class of hormones that circulate in the blood and are divided into two distinct groups, cardenolides, such as ouabain and digoxin, and bufadienolides, such as marinobufagenin, telocinobufagin and bufalin. They have the ability to bind and inhibit the ubiquitous transport enzyme sodium potassium pump, thus regulating intracellular Na(+) concentration in every living cell. Although digoxin has been prescribed to heart failure patients for at least 200 years, the realization that CTS are endogenously produced has intensified research into their physiological and pathophysiological roles. Over the last two decades, substantial evidence has accumulated demonstrating the effects of endogenously synthesised CTS on the kidneys, vasculature and the heart. In this review, the current state of art and the controversies surrounding the manner in which CTS mediate their pathophysiological effects are discussed. Several potential therapeutic strategies have emerged as a result of our increased understanding of the role CTS play in health and disease.
Collapse
Affiliation(s)
- Davor Pavlovic
- Cardiovascular Division, King's College London, Rayne Institute, St. Thomas' Hospital, London, UK
| |
Collapse
|
27
|
Khundmiri SJ. Advances in understanding the role of cardiac glycosides in control of sodium transport in renal tubules. J Endocrinol 2014; 222:R11-24. [PMID: 24781255 DOI: 10.1530/joe-13-0613] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cardiotonic steroids have been used for the past 200 years in the treatment of congestive heart failure. As specific inhibitors of membrane-bound Na(+)/K(+) ATPase, they enhance cardiac contractility through increasing myocardial cell calcium concentration in response to the resulting increase in intracellular Na concentration. The half-minimal concentrations of cardiotonic steroids required to inhibit Na(+)/K(+) ATPase range from nanomolar to micromolar concentrations. In contrast, the circulating levels of cardiotonic steroids under physiological conditions are in the low picomolar concentration range in healthy subjects, increasing to high picomolar levels under pathophysiological conditions including chronic kidney disease and heart failure. Little is known about the physiological function of low picomolar concentrations of cardiotonic steroids. Recent studies have indicated that physiological concentrations of cardiotonic steroids acutely stimulate the activity of Na(+)/K(+) ATPase and activate an intracellular signaling pathway that regulates a variety of intracellular functions including cell growth and hypertrophy. The effects of circulating cardiotonic steroids on renal salt handling and total body sodium homeostasis are unknown. This review will focus on the role of low picomolar concentrations of cardiotonic steroids in renal Na(+)/K(+) ATPase activity, cell signaling, and blood pressure regulation.
Collapse
Affiliation(s)
- Syed Jalal Khundmiri
- Division of Nephrology and HypertensionDepartment of MedicineDepartment of Physiology and BiophysicsUniversity of Louisville, 570 S. Preston Street, Louisville, Kentucky 40202, USADivision of Nephrology and HypertensionDepartment of MedicineDepartment of Physiology and BiophysicsUniversity of Louisville, 570 S. Preston Street, Louisville, Kentucky 40202, USA
| |
Collapse
|
28
|
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.
Collapse
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
| | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Lenaerts C, Demeyer M, Gerbaux P, Blankert B. Analytical aspects of marinobufagenin. Clin Chim Acta 2013; 421:193-201. [DOI: 10.1016/j.cca.2013.02.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 02/21/2013] [Accepted: 02/22/2013] [Indexed: 11/30/2022]
|
30
|
Elzwiei F, Bassien-Capsa V, St-Louis J, Chorvatova A. Regulation of the sodium pump during cardiomyocyte adaptation to pregnancy. Exp Physiol 2012; 98:183-92. [PMID: 22848078 DOI: 10.1113/expphysiol.2012.066282] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Regulation of the sodium pump during normal pregnancy and its effect on the function of cardiomyocytes is poorly understood. Our objective was to evaluate the possible implication of the Na(+)-K(+)-ATPase, the sodium pump which controls cellular ionic and metabolic homeostasis, in the adaptations of cardiomyocytes to normal pregnancy. We have used Western blots and patch-clamp measurements to identify changes in the sodium pump proteins. Confocal microscopy was applied to estimate intracellular sodium concentration. Time-resolved spectroscopy was employed to measure mitochondrial NAD(P)H fluorescence and estimate oxidative metabolic state. Optical microscopy was adopted to study the contractility responses of cardiomyocytes. Cells from non-pregnant and pregnant rats (1 day prior parturition) were studied. Our results showed lower protein expression of the α1 Na(+)-K(+)-ATPase isoform in cardiomyocytes in pregnant rats, decreased sodium pump membrane current and elevated steady-state sodium concentration. In addition, ouabain, the inhibitor of the sodium pump capable of increasing cardiomyocyte contractility in non-pregnant rats in a concentration-dependent manner, failed to affect cell contractions in pregnant rats. We also noted modified responsiveness of the mitochondrial metabolic state to ouabain in cardiac cells. The gathered data confirmed that in pregnant rats, the sodium pump protein content and transmembrane flux are decreased, while the sensitivity of cardiomyocyte contractility and the sensitivity of mitochondrial metabolic redox state to ouabain are modified, pointing to regulation of the Na(+)-K(+)-ATPase during cardiac cell adaptations to normal pregnancy.
Collapse
Affiliation(s)
- F Elzwiei
- CHU Sainte Justine, Research Centre, Montreal, Quebec, Canada H3T 1C5
| | | | | | | |
Collapse
|
31
|
Systemic hypertension: the roles of salt, vascular Na+/K+ ATPase and the endogenous glycosides, ouabain and marinobufagenin. Cardiol Rev 2012; 20:130-8. [PMID: 22183064 DOI: 10.1097/crd.0b013e31823c835c] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Essential hypertension has been shown to be significantly associated with an increased risk for cardiovascular disease and is not well controlled in many patients. In a large portion of people with essential hypertension, sodium intake has been shown to play a significant role in the production of their hypertension. The mechanism through which increased sodium intake manifests hypertension is unresolved and likely multifactorial. Endogenous cardiac glycosides such as endogenous ouabain (EO) and marinobufagenin have been proposed to play a role in salt-sensitive essential hypertension through their inhibition of Na/K ATPase (NKA). The normal function of the NKA pump is to extrude Na from the intracellular environment and import K. Blocking the NKA disrupts its normal maintenance function. EO is proposed to produce alteration in smooth muscle cell contractility by inhibiting the α2-isoform of NKA, altering Na in a microdomain of the cell. In this region of the plasma membrane the α2-isoform of the NKA colocalizes with another transmembrane protein, the Na/Ca exchanger (NCX). The normal function of NCX is to extrude Ca and import Na. Inhibition of NKA produces an increase in Na within the microdomain, which in turn alters the function of the NCX so that less Ca is extruded, leading to increased intracellular Ca and increased vascular contraction. EO has been shown to be synthesized and secreted by the adrenal cortex in response to chronically elevated sodium intake. The levels of EO have been shown to be significantly elevated in 40% of all untreated hypertensive patients. Marinobufagenin, another cardiac glycoside, has also been implicated as a possible cause of essential hypertension through its preferential inhibition of the α1-isoform of NKA. Antagonism of the endogenous inhibitors of NKA is currently a target of clinical research for the development of innovative antihypertensive treatments.
Collapse
|
32
|
Ishkaraeva-Yakovleva VV, Fedorova OV, Solodovnikova NG, Frolova EV, Bzhelyansky AM, Emelyanov IV, Adair CD, Zazerskaya IE, Bagrov AY. DigiFab interacts with endogenous cardiotonic steroids and reverses preeclampsia-induced Na/K-ATPase inhibition. Reprod Sci 2012; 19:1260-7. [PMID: 22649120 DOI: 10.1177/1933719112447124] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Elevated levels of endogenous Na/K-ATPase (NKA) inhibitors, cardiotonic steroids (CTSs) including marinobufagenin (MBG), contribute to pathogenesis of preeclampsia (PE) and represent a target for immunoneutralization by Digibind (Ovine Digoxin Immune Antibody, Glaxo-Smith Kline). Because Digibind is no longer commercially available, we studied whether DigiFab (BTG International Ltd, UK) can substitute Digibind for immunoneutralization of CTS in patients with PE. We compared DigiFab, Digibind, and anti-MBG monoclonal antibody (mAb) with respect to their ability to interact with CTS in PE plasma and to restore NKA activity in erythrocytes from patients with PE. Using immunoassays based on DigiFab, Digibind, and anti-MBG mAb, we studied the elution profile of CTS following high-performance liquid chromatography (HPLC) fractionation of PE plasma. Totally, 7 patients with mild PE (28 ± 2 years; gestational age, 39 ± 0.5 weeks; blood pressure 156 ± 5/94 ± 2 mm Hg) and 6 normotensive pregnant participants (28 ± 1 years; gestational age, 39 ± 0.4 weeks; blood pressure 111 ± 2/73 ± 2 mm Hg) were enrolled. Preeclampsia was associated with a substantial inhibition of erythrocyte NKA (1.47 ± 0.17 vs 2.65 ± 0.16 µmol Pi/mL per h in control group, P < .001). Ex vivo, at 10 µg/mL concentration, which is consistent with the clinical dosing of Digibind administered previously in PE, DigiFab and Digibind as well as anti-MBG mAb (0.5 µg/mL) restored erythrocyte NKA activity. Following HPLC fractionation of pooled PE and control plasma, PE-associated increase in CTS material was detected by Digibind (176 vs 75 pmoles), DigiFab (221 vs 70 pmoles), and anti-MBG mAb (1056 vs 421 pmoles). Therefore, because DigiFab interacts with CTS from PE plasma and reverses PE-induced NKA inhibition, it can substitute Digibind for immunoneutralization of CTS in patients with PE.
Collapse
Affiliation(s)
- Valentina V Ishkaraeva-Yakovleva
- Laboratory of Reproduction and Women's Health, Institutes of Neonatology and Heart and Vessels, Almazov Heart, Blood and Endocrinology Center, St. Petersburg, Russia
| | | | | | | | | | | | | | | | | |
Collapse
|
33
|
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.
Collapse
|
34
|
Fedorova L, Gatto-Weis C, Smaili S, Khurshid N, Shapiro JI, Malhotra D, Horrigan T. Down-regulation of the transcription factor snail in the placentas of patients with preeclampsia and in a rat model of preeclampsia. Reprod Biol Endocrinol 2012; 10:15. [PMID: 22360878 PMCID: PMC3298516 DOI: 10.1186/1477-7827-10-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 02/23/2012] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Placental malfunction in preeclampsia is believed to be a consequence of aberrant differentiation of trophoblast lineages and changes in utero-placental oxygenation. The transcription factor Snail, a master regulator molecule of epithelial-mesenchymal transition in embryonic development and in cancer, is shown to be involved in trophoblast differentiation as well. Moreover, Snail can be controlled by oxidative stress and hypoxia. Therefore, we examined the expression of Snail and its downstream target, e-cadherin, in human normal term, preterm and preeclamptic placentas, and in pregnant rats that developed preeclampsia-like symptoms in the response to a 20-fold increase in sodium intake. METHODS Western blotting analysis was used for comparative expression of Snail and e- cadherin in total protein extracts. Placental cells expressing Snail and e-cadherin were identified by immunohistochemical double-labeling technique. RESULTS The levels of Snail protein were decreased in human preeclamptic placentas by 30% (p < 0.01) compared to normal term, and in the rat model by 40% (p < 0.001) compared to control placentas. In preterm placentas, the levels of Snail expression varied, yet there was a strong trend toward statistical significance between preterm and preeclamptic placentas. In humans, e-cadherin protein level was 30% higher in preeclamptic (p < 0.05) placentas and similarly, but not significantly (p = 0.1), high in the preterm placentas compared to normal term. In the rat model of preeclampsia, e-cadherin was increased by 60% (p < 0.01). Immunohistochemical examination of human placentas demonstrated Snail-positive staining in the nuclei of the villous trophoblasts and mesenchymal cells and in the invasive trophoblasts of the decidua. In the rat placenta, the majority of Snail positive cells were spongiotrophoblasts of the junctional zone, while in the labyrinth, Snail-positive sinusoidal giant trophoblasts cells were found in some focal areas located close to the junctional zone. CONCLUSION We demonstrated that human preeclampsia and the salt-induced rat model of preeclampsia are associated with the reduced levels of Snail protein in placenta. Down-regulation of the transcription factor Snail in placental progenitor cell lineages, either by intrinsic defects and/or by extrinsic and maternal factors, may affect normal placenta development and function and thus contribute to the pathology of preeclampsia.
Collapse
Affiliation(s)
- Larisa Fedorova
- Department of Medicine, University of Toledo School of Medicine, Toledo, OH 43614, USA
| | - Cara Gatto-Weis
- Department of Pathology, University of Toledo School of Medicine, Toledo, OH 43614, USA
| | - Sleiman Smaili
- Department of Obstetrics and Gynecology, University of Toledo School of Medicine, Toledo, OH 43614, USA
| | - Nauman Khurshid
- Department of Obstetrics and Gynecology, University of Toledo School of Medicine, Toledo, OH 43614, USA
| | - Joseph I Shapiro
- Department of Medicine, University of Toledo School of Medicine, Toledo, OH 43614, USA
| | - Deepak Malhotra
- Department of Medicine, University of Toledo School of Medicine, Toledo, OH 43614, USA
| | - Terrence Horrigan
- Department of Obstetrics and Gynecology, University of Toledo School of Medicine, Toledo, OH 43614, USA
| |
Collapse
|
35
|
Jacobs BE, Liu Y, Pulina MV, Golovina VA, Hamlyn JM. Normal pregnancy: mechanisms underlying the paradox of a ouabain-resistant state with elevated endogenous ouabain, suppressed arterial sodium calcium exchange, and low blood pressure. Am J Physiol Heart Circ Physiol 2012; 302:H1317-29. [PMID: 22245773 DOI: 10.1152/ajpheart.00532.2011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Endogenous cardiotonic steroids (CTS) raise blood pressure (BP) via vascular sodium calcium exchange (NCX1.3) and transient receptor-operated channels (TRPCs). Circulating CTS are superelevated in pregnancy-induced hypertension and preeclampsia. However, their significance in normal pregnancy, where BP is low, is paradoxical. Here we test the hypothesis that vascular resistance to endogenous ouabain (EO) develops in normal pregnancy and is mediated by reduced expression of NCX1.3 and TRPCs. We determined plasma and adrenal levels of EO and the impact of exogenous ouabain in pregnancy on arterial expression of Na(+) pumps, NCX1.3, TRPC3, and TRPC6 and BP. Pregnant (embryonic day 4) and nonpregnant rats received infusions of ouabain or vehicle. At 14-16 days, tissues and plasma were collected for blotting and EO assay by radioimmunoassay (RIA), liquid chromatography (LC)-RIA, and LC-multidimensional mass spectrometry (MS3). BP (-8 mmHg; P < 0.05) and NCX1.3 expression fell (aorta -60% and mesenteric artery -30%; P < 0.001) in pregnancy while TRPC expression was unchanged. Circulating EO increased (1.14 ± 0.13 nM) vs. nonpregnant (0.6 ± 0.08 nM; P < 0.05) and was confirmed by LC-MS3 and LC-RIA. LC-MS3 revealed two previously unknown isomers of EO; one increased ∼90-fold in pregnancy. Adrenal EO but not isomers were increased in pregnancy. In nonpregnant rats, similar infusions of ouabain raised BP (+24 ± 3 mmHg; P < 0.001). In ouabain-infused rats, impaired fetal and placental growth occurred with no BP increase. In summary, normal pregnancy is an ouabain-resistant state associated with low BP, elevated circulating levels of EO, two novel steroidal EO isomers, and increased adrenal mass and EO content. Ouabain raises BP only in nonpregnant animals. Vascular resistance to the chronic pressor activity of endogenous and exogenous ouabain is mediated by suppressed NCX1.3 and reduced sensitivity of events downstream of Ca(2+) entry. The mechanisms of EO resistance and the impaired fetal and placental growth due to elevated ouabain may be important in pregnancy-induced hypertension (PIH) and preeclampsia (PE).
Collapse
Affiliation(s)
- Brandiese E Jacobs
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, USA
| | | | | | | | | |
Collapse
|
36
|
Takahashi H, Yoshika M, Komiyama Y, Nishimura M. The central mechanism underlying hypertension: a review of the roles of sodium ions, epithelial sodium channels, the renin-angiotensin-aldosterone system, oxidative stress and endogenous digitalis in the brain. Hypertens Res 2011; 34:1147-60. [PMID: 21814209 PMCID: PMC3324327 DOI: 10.1038/hr.2011.105] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 05/08/2011] [Accepted: 05/15/2011] [Indexed: 02/07/2023]
Abstract
The central nervous system has a key role in regulating the circulatory system by modulating the sympathetic and parasympathetic nervous systems, pituitary hormone release, and the baroreceptor reflex. Digoxin- and ouabain-like immunoreactive materials were found >20 years ago in the hypothalamic nuclei. These factors appeared to localize to the paraventricular and supraoptic nuclei and the nerve fibers at the circumventricular organs and supposed to affect electrolyte balance and blood pressure. The turnover rate of these materials increases with increasing sodium intake. As intracerebroventricular injection of ouabain increases blood pressure via sympathetic activation, an endogenous digitalis-like factor (EDLF) was thought to regulate cardiovascular system-related functions in the brain, particularly after sodium loading. Experiments conducted mainly in rats revealed that the mechanism of action of ouabain in the brain involves sodium ions, epithelial sodium channels (ENaCs) and the renin-angiotensin-aldosterone system (RAAS), all of which are affected by sodium loading. Rats fed a high-sodium diet develop elevated sodium levels in their cerebrospinal fluid, which activates ENaCs. Activated ENaCs and/or increased intracellular sodium in neurons activate the RAAS; this releases EDLF in the brain, activating the sympathetic nervous system. The RAAS promotes oxidative stress in the brain, further activating the RAAS and augmenting sympathetic outflow. Angiotensin II and aldosterone of peripheral origin act in the brain to activate this cascade, increasing sympathetic outflow and leading to hypertension. Thus, the brain Na(+)-ENaC-RAAS-EDLF axis activates sympathetic outflow and has a crucial role in essential and secondary hypertension. This report provides an overview of the central mechanism underlying hypertension and discusses the use of antihypertensive agents.
Collapse
Affiliation(s)
- Hakuo Takahashi
- Department of Clinical Sciences and Laboratory Medicine, Kansai Medical University, Hirakata City, Osaka, Japan.
| | | | | | | |
Collapse
|
37
|
Yoshika M, Komiyama Y, Takahashi H. Isolation of marinobufotoxin from the supernatant of cultured PC12 cells. Clin Exp Pharmacol Physiol 2011; 38:334-7. [PMID: 21401694 DOI: 10.1111/j.1440-1681.2011.05512.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. Digitalis-like factors (DLFs) are believed to be involved in sodium metabolism via inhibition of Na(+) /K(+) -ATPase and may cause hypertension. Yet, the source and regulation of secretion of DLFs remain unknown. Recently, marinobufagenin (MBG) was isolated in mammals and implicated in renal sodium and water metabolism. More recently, we isolated marinobufotoxin (MBT), a suberoyl arginine ester of MBG, in Y-1 cells. We have developed an ELISA to measure MBG-like immunoreactivity (MBG-IR) and have characterized MBG-IR using chromatography. We have also identified a ouabain-like factor in cultured PC12 cells from a phaeochromocytoma cell line. In the present study, we examined whether MBT was produced in the adrenal medulla. 2. PC12 cells were cultured in serum-free medium and culture supernatants were collected over a period of 24 h. The supernatants were analysed by ELISA and HPLC to determine MBG-IR content. The HPLC fraction containing the main peak of MBG-IR was characterized by LC/MS. 3. Compared with samples collected at 0.5 h, the concentration of MBG-IR in culture supernatants increased significantly after 2 h and continued to increase until 24 h. The fraction with the highest ELISA peak for MBG-IR had the same HPLC elution time as authentic MBT. Furthermore, tandem mass spectrometry indicated that each fraction of MBT and MBG had the correct specific daughter ions. 4. The results indicate that MBT and MBG are produced and/or secreted by adrenomedullary cells.
Collapse
Affiliation(s)
- Masamichi Yoshika
- Department of Clinical Sciences and Laboratory Medicine, Kansai Medical University, Osaka, Japan
| | | | | |
Collapse
|
38
|
In preeclampsia endogenous cardiotonic steroids induce vascular fibrosis and impair relaxation of umbilical arteries. J Hypertens 2011; 29:769-76. [PMID: 21330936 DOI: 10.1097/hjh.0b013e32834436a7] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Marinobufagenin (MBG), a bufadienolide cardiotonic steroid, induces cardiovascular fibrosis. Because levels of MBG in preeclampsia are increased, and anti-MBG monoclonal antibody reduces blood pressure (BP) in a rat model of preeclampsia, we hypothesized that in preeclampsia, elevated MBG levels would be associated with the development of fibrosis in feto-placental circulation and with impairment of vascular relaxation. METHOD We studied 16 patients with preeclampsia (systolic BP=150±4 mmHg; 28±2 years, 37±1 weeks gestational age) and 14 gestational age-matched normal pregnant women (systolic BP=112±2 mmHg). RESULTS Preeclampsia was associated with a rise in plasma and placental levels of MBG. In preeclamptic umbilical arteries, the expression of Fli-1, a transcription factor and a negative regulator of fibrosis, was significantly reduced (P<0.001), whereas procollagen-1 expression was increased (P<0.01). As compared to control vessels, isolated rings of umbilical arteries from patients with preeclampsia demonstrated unaltered responsiveness to endothelin-1 (EC50=2.2 and 3.2 nmol/l, respectively), but exhibited an impaired response to the relaxant effect of sodium nitroprusside (EC50=1.5 vs. 32.4 nmol/l, P<.001) following endothelin-1-induced constriction. Ex-vivo treatment of normal umbilical arteries explants with 1 and 10 nmol/l MBG for 24 h mimicked the effects of preeclampsia, specifically suppressed Fli-1 and increased collagen-1 expression while impairing vasorelaxation. CONCLUSION Our results indicate that in preeclampsia, elevated levels of MBG induce vascular fibrosis via a Fli-1-dependent mechanism which leads to an impairment of vasorelaxation, and suggest that MBG represents a potential target for therapy of this syndrome.
Collapse
|
39
|
Liu J, Yan Y, Liu L, Xie Z, Malhotra D, Joe B, Shapiro JI. Impairment of Na/K-ATPase signaling in renal proximal tubule contributes to Dahl salt-sensitive hypertension. J Biol Chem 2011; 286:22806-13. [PMID: 21555512 DOI: 10.1074/jbc.m111.246249] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
We have observed that, in renal proximal tubular cells, cardiotonic steroids such as ouabain in vitro signal through Na/K-ATPase, which results in inhibition of transepithelial (22)Na(+) transport by redistributing Na/K-ATPase and NHE3. In the present study, we investigate the role of Na/K-ATPase signaling in renal sodium excretion and blood pressure regulation in vivo. In Sprague-Dawley rats, high salt diet activated c-Src and induced redistribution of Na/K-ATPase and NHE3 in renal proximal tubules. In Dahl salt sensitive (S) and resistant (R) rats given high dietary salt, we found different effects on blood pressure but, more interestingly, different effects on renal salt handling. These differences could be explained by different signaling through the proximal tubular Na/K-ATPase. Specifically, in Dahl R rats, high salt diet significantly stimulated phosphorylation of c-Src and ERK1/2, reduced Na/K-ATPase activity and NHE3 activity, and caused redistribution of Na/K-ATPase and NHE3. In contrast, these adaptations were either much less effective or not seen in the Dahl S rats. We also studied the primary culture of renal proximal tubule isolated from Dahl S and R rats fed a low salt diet. In this system, ouabain induced Na/K-ATPase/c-Src signaling and redistribution of Na/K-ATPase and NHE3 in the Dahl R rats, but not in the Dahl S rats. Our data suggested that impairment of Na/K-ATPase signaling and consequent regulation of Na/K-ATPase and NHE3 in renal proximal tubule may contribute to salt-induced hypertension in the Dahl S rat.
Collapse
Affiliation(s)
- Jiang Liu
- Department of Medicine, University of Toledo College of Medicine, Toledo, Ohio 43614, USA.
| | | | | | | | | | | | | |
Collapse
|
40
|
Oshiro N, Dostanic-Larson I, Neumann JC, Lingrel JB. The ouabain-binding site of the α2 isoform of Na,K-ATPase plays a role in blood pressure regulation during pregnancy. Am J Hypertens 2010; 23:1279-85. [PMID: 20940714 DOI: 10.1038/ajh.2010.195] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The cardiotonic steroid/ouabain-binding site of the α subunit of Na,K-ATPase is thought to play an important role in cardiovascular homeostasis. Previously, we demonstrated the cardiotonic steroid-binding site of the α2 Na,K-ATPase is involved in adrenocorticotropic hormone (ACTH)-induced hypertension by using gene-modified α2(R/R) mice in which the cardiotonic steroid-binding site is relatively resistant to ouabain compared to the ouabain-sensitive wild-type α2(S/S) mice. To further explore the importance of this site in the cardiovascular system, we investigated blood pressure regulation during pregnancy in mice with the α2(R/R) isoform. METHODS The systolic blood pressure (SBP) of the α2(S/S) and α2(R/R) mice was measured before and during pregnancy by tail-cuff. The expression of the α isoforms of Na, K-ATPase in various tissues and plasma endogenous ouabain contents were assessed prior to pregnancy as well as days 7 and 17 of gestation. RESULTS The α2(S/S) mice showed a gradual decrease in the SBP during the first two trimesters, followed by an increase above the preconceptional level in the third trimester. However, the α2(R/R) mice exhibited a lower blood pressure in the third trimester. The cardiac expression of the α2 Na,K-ATPase in the α2(S/S) mice was significantly less than that of the α2(R/R) mice throughout the pregnancy. The plasma endogenous ouabain concentration significantly increased by twofold at day 17 of pregnancy in the α2(R/R) mice but not in the α2(S/S) mice. CONCLUSIONS The cardiotonic steroid-binding site of the α2 Na,K-ATPase plays a role in maintaining normal SBP during pregnancy.
Collapse
|
41
|
Puschett JB, Agunanne E, Uddin MN. Emerging Role of the Bufadienolides in Cardiovascular and Kidney Diseases. Am J Kidney Dis 2010; 56:359-70. [DOI: 10.1053/j.ajkd.2010.01.023] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 01/05/2010] [Indexed: 01/11/2023]
|
42
|
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: 225] [Impact Index Per Article: 16.1] [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.
Collapse
Affiliation(s)
- Jerry B Lingrel
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0524, USA.
| |
Collapse
|
43
|
Abstract
BACKGROUND Preeclampsia is a major cause of maternal and fetal mortality, and its pathogenesis is not fully understood. Endogenous digitalis-like cardiotonic steroids (CTS) have been implicated in the pathophysiology of preeclampsia; this is illustrated by clinical observations that Digibind, a therapeutic digoxin antibody fragment which binds CTS, lowers blood pressure and reverses Na/K-ATPase inhibition in patients with preeclampsia. Recently we reported that plasma levels of marinobufagenin (MBG), a bufadienolide vasoconstrictor CTS, are increased four-fold in patients with severe preeclampsia. METHODS In the present study, we compared levels of MBG in normal and preeclamptic placentae, as well as the interactions of Digibind and antibodies against MBG and ouabain with material purified from preeclamptic placentae using high-performance liquid chromatography (HPLC). RESULTS Levels of endogenous MBG, but not that of endogenous ouabain, exhibited a four-fold elevation in preeclamptic placentae vs. normal placentae (13.6 +/- 2.5 and 48.6 +/- 7.0 nmoles/g tissue; P < 0.01). The elution time of endogenous placental MBG-like immunoreactive material from reverse-phase HPLC column was identical to that of authentic MBG. A competitive immunoassay based on Digibind exhibited reactivity to HPLC fractions having retention times similar to that seen with MBG and other bufadienolides, but not to ouabain-like immunoreactive material. CONCLUSIONS Our results suggest that elevated levels of endogenous bufadienolide CTS represent a potential target for immunoneutralization in patients with preeclampsia.
Collapse
|
44
|
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.
Collapse
Affiliation(s)
- J B Puschett
- Department of Medicine, Texas A&M Health Science Center, Temple, TX 76508, USA.
| | | | | |
Collapse
|
45
|
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.
Collapse
|
46
|
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: 384] [Impact Index Per Article: 25.6] [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.
Collapse
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.
| | | | | |
Collapse
|
47
|
Monoclonal antibody to an endogenous bufadienolide, marinobufagenin, reverses preeclampsia-induced Na/K-ATPase inhibition and lowers blood pressure in NaCl-sensitive hypertension. J Hypertens 2009; 26:2414-25. [PMID: 19008721 DOI: 10.1097/hjh.0b013e328312c86a] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Levels of marinobufagenin (MBG), an endogenous bufadienolide Na/K-ATPase (NKA) inhibitor, increase in preeclampsia and in NaCl-sensitive hypertension. METHODS We tested a 3E9 monoclonal anti-MBG antibody (mAb) for the ability to lower blood pressure (BP) in NaCl-sensitive hypertension and to reverse the preeclampsia-induced inhibition of erythrocyte NKA. Measurements of MBG were performed via immunoassay based on 4G4 anti-MBG mAb. RESULTS In hypertensive Dahl-S rats, intraperitoneal administration of 50 microg/kg 3E9 mAb lowered BP by 32 mmHg and activated the Na/K-pump in the thoracic aorta by 51%. NaCl supplementation of pregnant rats (n = 16) produced a 37 mmHg increase in BP, a 3.5-fold rise in MBG excretion, and a 25% inhibition of the Na/K-pump in the thoracic aorta, compared with pregnant rats on a normal NaCl intake. In eight pregnant hypertensive rats, 3E9 mAb reduced the BP (21 mmHg) and restored the vascular Na/K-pump. In 14 patients with preeclampsia (mean BP, 126 +/- 3 mmHg; 26.9 +/- 1.4 years; gestational age, 37 +/- 0.8 weeks), plasma MBG was increased three-fold and erythrocyte NKA was inhibited compared with that of 12 normotensive pregnant women (mean BP, 71 +/- 3 mmHg) (1.5 +/- 0.1 vs. 3.1 +/- 0.2 micromol Pi/ml/h, respectively; P < 0.01). Ex-vivo 3E9 mAb restored NKA activity in erythrocytes from patients with preeclampsia. As compared with 3E9 mAb, Digibind, an affinity-purified antidigoxin antibody, was less active with respect to lowering BP in both hypertensive models and to restoration of NKA from erythrocytes from patients with preeclampsia. CONCLUSION Anti-MBG mAbs may be a useful tool in studies of MBG in vitro and in vivo and may offer treatment of preeclampsia.
Collapse
|
48
|
Bagrov AY, Shapiro JI. Endogenous digitalis: pathophysiologic roles and therapeutic applications. NATURE CLINICAL PRACTICE. NEPHROLOGY 2008; 4:378-92. [PMID: 18542120 PMCID: PMC2574729 DOI: 10.1038/ncpneph0848] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Accepted: 04/29/2008] [Indexed: 12/22/2022]
Abstract
Endogenous digitalis-like factors, also called cardiotonic steroids, have been thought for nearly half a century to have important roles in health and disease. The endogenous cardiotonic steroids ouabain and marinobufagenin have been identified in humans, and an effector mechanism has been delineated by which these hormones signal through the sodium/potassium-transporting ATPase. These findings have increased interest in this field substantially. Although cardiotonic steroids were first considered important in the regulation of renal sodium transport and arterial pressure, subsequent work has implicated these hormones in the control of cell growth, apoptosis and fibrosis, among other processes. This Review focuses on the role of endogenous cardiotonic steroids in the pathophysiology of essential hypertension, congestive heart failure, end-stage renal disease and pre-eclampsia. We also discuss potential therapeutic strategies that have emerged as a result of the increased understanding of the regulation and actions of cardiotonic steroids.
Collapse
Affiliation(s)
- Alexei Y Bagrov
- Hypertension Unit at Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore 21224, MD, USA.
| | | |
Collapse
|
49
|
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
|
50
|
Uddin MN, Horvat D, Glaser SS, Mitchell BM, Puschett JB. Examination of the cellular mechanisms by which marinobufagenin inhibits cytotrophoblast function. J Biol Chem 2008; 283:17946-53. [PMID: 18434301 DOI: 10.1074/jbc.m800958200] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Marinobufagenin (MBG) is an endogenous mammalian cardiotonic steroid involved in the inhibition of Na(+)/K(+)-ATPase. Increased plasma levels have been reported in patients with volume expansion-related hypertension. We have recently demonstrated that MBG impairs first trimester cytotrophoblast (CTB) cell proliferation, migration, and invasion, which may play a role in the development of preeclampsia. However, whether apoptosis contributes to altered CTB cell function by MBG remains unknown. Using the human extravillous CTB cell line SGHPL-4, we examined the effect of MBG and a similar Na(+)/K(+)-ATPase inhibitor, ouabain, on the phosphorylation status of Jnk, p38, and Src. Additionally, we measured apoptosis by caspase 9 and 3/7 activity and by annexin-V staining. We also investigated interleukin-6 (IL-6) secretion with or without p38 and Jnk inhibition. MBG significantly increased the phosphorylation of Jnk, p38, and Src and increased the expression of caspase 9 and 3/7 indicating the activation of apoptosis. MBG treatment also stimulated the expression of the early apoptosis marker, annexin-V, which was prevented by Jnk and p38 inhibition. MBG also stimulated the secretion of IL-6, which was attenuated by p38 inhibition. Ouabain had similar effects to those of MBG, suggesting that the apoptotic effects on CTB cells may be mediated by inhibition of Na(+)/K(+)-ATPase. In conclusion, the MBG-induced impairment of CTB function occurs via activation of Jnk, p38, and Src leading to increased apoptosis and IL-6 secretion. These observations may have clinical applicability with respect to the therapy of preeclampsia.
Collapse
Affiliation(s)
- Mohammad N Uddin
- Division of Nephrology and Hypertension, Department of Medicine, Texas A&M Health Science Center, Scott and White Clinic, Temple, TX 76508, USA
| | | | | | | | | |
Collapse
|