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Orth T, Pyanova A, Lux S, Kaiser P, Reinheimer I, Nielsen DL, Khalid JA, Rognant S, Jepps TA, Matchkov VV, Schubert R. Vascular smooth muscle BK channels limit ouabain-induced vasocontraction: Dual role of the Na/K-ATPase as a hub for Src-kinase and the Na/Ca-exchanger. FASEB J 2024; 38:e70046. [PMID: 39259502 DOI: 10.1096/fj.202400628rr] [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: 03/22/2024] [Revised: 08/20/2024] [Accepted: 08/29/2024] [Indexed: 09/13/2024]
Abstract
Large-conductance, calcium-activated potassium channels (BK channels) and the Na/K-ATPase are expressed universally in vascular smooth muscle. The Na/K-ATPase may act via changes in the intracellular Ca2+ concentration mediated by the Na/Ca exchanger (NCX) and via Src kinase. Both pathways are known to regulate BK channels. Whether BK channels functionally interact in vascular smooth muscle cells with the Na/K-ATPase remains to be elucidated. Thus, this study addressed the hypothesis that BK channels limit ouabain-induced vasocontraction. Rat mesenteric arteries were studied using isometric myography, FURA-2 fluorimetry and proximity ligation assay. The BK channel blocker iberiotoxin potentiated methoxamine-induced contractions. The cardiotonic steroid, ouabain (10-5 M), induced a contractile effect of IBTX at basal tension prior to methoxamine administration and enhanced the pro-contractile effect of IBTX on methoxamine-induced contractions. These facilitating effects of ouabain were prevented by the inhibition of either NCX or Src kinase. Furthermore, inhibition of NCX or Src kinase reduced the BK channel-mediated negative feedback regulation of arterial contraction. The effects of NCX and Src kinase inhibition were independent of each other. Co-localization of the Na/K-ATPase and the BK channel was evident. Our data suggest that BK channels limit ouabain-induced vasocontraction by a dual mechanism involving the NCX and Src kinase signaling. The data propose that the NCX and the Src kinase pathways, mediating the ouabain-induced activation of the BK channel, act in an independent manner.
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Affiliation(s)
- Tobias Orth
- Research Division Cardiovascular Physiology, European Center of Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Anastasia Pyanova
- Physiology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Augsburg, Germany
| | - Simon Lux
- Research Division Cardiovascular Physiology, European Center of Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Peter Kaiser
- Research Division Cardiovascular Physiology, European Center of Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Isabel Reinheimer
- Research Division Cardiovascular Physiology, European Center of Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | | | - Josef Ali Khalid
- Department of Biomedicine, Health, Aarhus University, Aarhus, Denmark
| | - Salomé Rognant
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas A Jepps
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Rudolf Schubert
- Research Division Cardiovascular Physiology, European Center of Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Physiology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Augsburg, Germany
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Tang M, Hu J, Li W, Zhang N, Ning S, Yan Y, Cui Z. Effects of Renal Denervation on Ouabain-Induced Hypertension in Rats. Int J Hypertens 2024; 2024:4763189. [PMID: 38957519 PMCID: PMC11217579 DOI: 10.1155/2024/4763189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 05/04/2024] [Accepted: 05/28/2024] [Indexed: 07/04/2024] Open
Abstract
Background Ouabain, a Na+, K+-ATPase inhibitor, is elevated in hypertensive patients. Evidence suggests ouabain contributes to hypertension mainly through activation of the sympathetic nervous system (SNS). Renal nerves play a vital role in the regulation of SNS activity, so we hypothesize that renal denervation may attenuate the development of ouabain-induced hypertension. Methods and Results Forty Sprague-Dawley rats were divided into following groups (n = 10 each): control group (sham surgery plus intraperitoneal saline injection), RDN group (renal denervation (RDN) plus intraperitoneal saline injection), ouabain group (sham surgery plus intraperitoneal ouabain injection), and ouabain + RDN group (RDN plus intraperitoneal ouabain injection). After eight weeks, compared with the control group, rats in the ouabain group exhibited elevated blood pressure (P < 0.05), increased plasma epinephrine, norepinephrine, angiotensin II, and aldosterone levels (P < 0.05). These indexes could be significantly ameliorated by RDN. RDN also reduced the thickening of aortic tunica media and downregulated the expression of proliferating cell nuclear antigen (PCNA) in the thoracic aorta induced by ouabain. Masson staining and echocardiography showed that myocardial fibrosis and increased left ventricular mass in the ouabain group could be attenuated by RDN. Conclusions The present study reveals that renal nerves play an important role in the development of ouabain-induced hypertension. RDN could inhibit the pressor effect and the myocardial remodeling induced by ouabain potentially via inhibiting catecholamine release and vascular smooth muscle cell proliferation. Clinical studies are needed to explore whether RDN may exhibit better antihypertensive effects on hypertensive patients with high plasma ouabain levels as compared to those with normal plasma ouabain levels.
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Affiliation(s)
- Minna Tang
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Diseases, Shanghai, China
| | - Jialu Hu
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Diseases, Shanghai, China
| | - Wenshu Li
- School of Public Health, Fudan University, Shanghai, 200032, China
| | - Ningzhi Zhang
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Diseases, Shanghai, China
| | - Sisi Ning
- Department of Cardiology, Shanghai Changning Tianshan Traditional Chinese Medicine Hospital, Shanghai 200051, China
| | - Yan Yan
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Diseases, Shanghai, China
| | - Zhaoqiang Cui
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai Institute of Cardiovascular Diseases, Shanghai, China
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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.
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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
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Staehr C, Aalkjaer C, Matchkov V. The vascular Na,K-ATPase: clinical implications in stroke, migraine, and hypertension. Clin Sci (Lond) 2023; 137:1595-1618. [PMID: 37877226 PMCID: PMC10600256 DOI: 10.1042/cs20220796] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 10/05/2023] [Accepted: 10/09/2023] [Indexed: 10/26/2023]
Abstract
In the vascular wall, the Na,K-ATPase plays an important role in the control of arterial tone. Through cSrc signaling, it contributes to the modulation of Ca2+ sensitivity in vascular smooth muscle cells. This review focuses on the potential implication of Na,K-ATPase-dependent intracellular signaling pathways in severe vascular disorders; ischemic stroke, familial migraine, and arterial hypertension. We propose similarity in the detrimental Na,K-ATPase-dependent signaling seen in these pathological conditions. The review includes a retrospective proteomics analysis investigating temporal changes after ischemic stroke. The analysis revealed that the expression of Na,K-ATPase α isoforms is down-regulated in the days and weeks following reperfusion, while downstream Na,K-ATPase-dependent cSrc kinase is up-regulated. These results are important since previous studies have linked the Na,K-ATPase-dependent cSrc signaling to futile recanalization and vasospasm after stroke. The review also explores a link between the Na,K-ATPase and migraine with aura, as reduced expression or pharmacological inhibition of the Na,K-ATPase leads to cSrc kinase signaling up-regulation and cerebral hypoperfusion. The review discusses the role of an endogenous cardiotonic steroid-like compound, ouabain, which binds to the Na,K-ATPase and initiates the intracellular cSrc signaling, in the pathophysiology of arterial hypertension. Currently, our understanding of the precise control mechanisms governing the Na,K-ATPase/cSrc kinase regulation in the vascular wall is limited. Understanding the role of vascular Na,K-ATPase signaling is essential for developing targeted treatments for cerebrovascular disorders and hypertension, as the Na,K-ATPase is implicated in the pathogenesis of these conditions and may contribute to their comorbidity.
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Affiliation(s)
- Christian Staehr
- Department of Biomedicine, Aarhus University, Høegh-Guldbergsgade 10, 8000 Aarhus, Denmark
- Department of Renal Medicine, Aarhus University Hospital, Palle Juul-Jensens Boulevard 35, Aarhus, Denmark
| | - Christian Aalkjaer
- Department of Biomedicine, Aarhus University, Høegh-Guldbergsgade 10, 8000 Aarhus, Denmark
- Danish Cardiovascular Academy, Høegh-Guldbergsgade 10, 8000 Aarhus, Denmark
| | - Vladimir V. Matchkov
- Department of Biomedicine, Aarhus University, Høegh-Guldbergsgade 10, 8000 Aarhus, Denmark
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Lai X, Wen H, Yang T, Qin F, Zhong X, Pan Y, Yu J, Huang J, Li J. Effects of renal denervation on endogenous ouabain in spontaneously hypertensive rats. Acta Cir Bras 2023; 37:e371102. [PMID: 36629529 PMCID: PMC9829196 DOI: 10.1590/acb371102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 10/12/2022] [Indexed: 01/11/2023] Open
Abstract
PURPOSE To investigate the role of renal denervation (RDN) on endogenous ouabain (EO) secretion in spontaneously hypertensive rats (SHR). METHODS Sixteen 12-week-old male SHR were randomly separated into the renal denervation group (RDNX group) and sham operation group (sham group), and eight age-matched Wistar Kyoto rats (WKY) were served as control group. EO concentrations, the Na+- K+-ATPaseactivity, and the expression of Na+-K+-ATPase were assessed. RESULTS EO levels in serum, kidneys and hypothalamus of sham group were higher than in RDNX group (p < 0.05). Renal Na+-K+-ATPase activity subjected to denervation surgery showed significantly reduction when compared with the sham groups (p < 0.05). A positive correlation existed between norepinephrine (NE) content and Na+-K+-ATPase activity in the kidney (r2 = 0.579). Renal Na+-K+-ATPase α1 subunit mRNA expression was down-regulated in the RDNX group compared with the sham group (P < 0.05), while renal Na+-K+-ATPase α1 subunit mRNA expression was no statistical significance between the groups (P = 0.63). Immunohistochemical analysis showed that there were significant differences in the renal expression of Na+-K+-ATPasebetween the three groups (P < 0.05). CONCLUSIONS These experiments demonstrate that RDN exerted an anti-hypertensive effect with reduction of EO levels and Na+-K+-ATPase activity and Na+-K+-ATPase α1 subunit expression of kidney in SHR.
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Affiliation(s)
- Xiaomei Lai
- Postgraduate. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Hong Wen
- PhD. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Tingting Yang
- Postgraduate. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Fei Qin
- Postgraduate. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Xiaoge Zhong
- Postgraduate. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Yajin Pan
- Postgraduate. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Jie Yu
- Postgraduate. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Jing Huang
- Postgraduate. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China
| | - Jianling Li
- PhD, and Postdoctoral Mobile Station. Guangxi Medical University – First Affiliated Hospital – Department of Cardiology – Nanning, China.,Corresponding author:
- 13407710624
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Blaustein MP, Gottlieb SS, Hamlyn JM, Leenen FHH. Whither digitalis? What we can still learn from cardiotonic steroids about heart failure and hypertension. Am J Physiol Heart Circ Physiol 2022; 323:H1281-H1295. [PMID: 36367691 DOI: 10.1152/ajpheart.00362.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Cloning of the "Na+ pump" (Na+,K+-ATPase or NKA) and identification of a circulating ligand, endogenous ouabain (EO), a cardiotonic steroid (CTS), triggered seminal discoveries regarding EO and its NKA receptor in cardiovascular function and the pathophysiology of heart failure (HF) and hypertension. Cardiotonic digitalis preparations were a preferred treatment for HF for two centuries, but digoxin was only marginally effective in a large clinical trial (1997). This led to diminished digoxin use. Missing from the trial, however, was any consideration that endogenous CTS might influence digitalis' efficacy. Digoxin, at therapeutic concentrations, acutely inhibits NKA but, remarkably, antagonizes ouabain's action. Prolonged treatment with ouabain, but not digoxin, causes hypertension in rodents; in this model, digoxin lowers blood pressure (BP). Furthermore, NKA-bound ouabain and digoxin modulate different protein kinase signaling pathways and have disparate long-term cardiovascular effects. Reports of "brain ouabain" led to the elucidation of a new, slow neuromodulatory pathway in the brain; locally generated EO and the α2 NKA isoform help regulate sympathetic drive to the heart and vasculature. The roles of EO and α2 NKA have been studied by EO assay, ouabain-resistant mutation of α2 NKA, and immunoneutralization of EO with ouabain-binding Fab fragments. The NKA α2 CTS binding site and its endogenous ligand are required for BP elevation in many common hypertension models and full expression of cardiac remodeling and dysfunction following pressure overload or myocardial infarction. Understanding how endogenous CTS impact hypertension and HF pathophysiology and therapy should foster reconsideration of digoxin's therapeutic utility.
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Affiliation(s)
- Mordecai P Blaustein
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland.,Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Stephen S Gottlieb
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - John M Hamlyn
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Frans H H Leenen
- Brain and Heart Research Group, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
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Role of Translationally Controlled Tumor Protein (TCTP) in the Development of Hypertension and Related Diseases in Mouse Models. Biomedicines 2022; 10:biomedicines10112722. [DOI: 10.3390/biomedicines10112722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 10/24/2022] [Accepted: 10/24/2022] [Indexed: 11/16/2022] Open
Abstract
Translationally controlled tumor protein (TCTP) is a multifunctional protein that plays a wide variety of physiological and pathological roles, including as a cytoplasmic repressor of Na,K-ATPase, an enzyme pivotal in maintaining Na+ and K+ ion gradients across the plasma membrane, by binding to and inhibiting Na,K-ATPase. Studies with transgenic mice overexpressing TCTP (TCTP-TG) revealed the pathophysiological significance of TCTP in the development of systemic arterial hypertension. Overexpression of TCTP and inhibition of Na,K-ATPase result in the elevation of cytoplasmic Ca2+ levels, which increases the vascular contractility in the mice, leading to hypertension. Furthermore, studies using an animal model constructed by multiple mating of TCTP-TG with apolipoprotein E knockout mice (ApoE KO) indicated that TCTP-induced hypertension facilitates the severity of atherosclerotic lesions in vivo. This review attempts to discuss the mechanisms underlying TCTP-induced hypertension and related diseases gleaned from studies using genetically altered animal models and the potential of TCTP as a target in the therapy of hypertension-related pathological conditions.
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Short-Term Mild Hypoxia Modulates Na,K-ATPase to Maintain Membrane Electrogenesis in Rat Skeletal Muscle. Int J Mol Sci 2022; 23:ijms231911869. [PMID: 36233169 PMCID: PMC9570130 DOI: 10.3390/ijms231911869] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/26/2022] [Accepted: 09/30/2022] [Indexed: 11/17/2022] Open
Abstract
The Na,K-ATPase plays an important role in adaptation to hypoxia. Prolonged hypoxia results in loss of skeletal muscle mass, structure, and performance. However, hypoxic preconditioning is known to protect against a variety of functional impairments. In this study, we tested the possibility of mild hypoxia to modulate the Na,K-ATPase and to improve skeletal muscle electrogenesis. The rats were subjected to simulated high-altitude (3000 m above sea level) hypobaric hypoxia (HH) for 3 h using a hypobaric chamber. Isolated diaphragm and soleus muscles were tested. In the diaphragm muscle, HH increased the α2 Na,K-ATPase isozyme electrogenic activity and stably hyperpolarized the extrajunctional membrane for 24 h. These changes were accompanied by a steady increase in the production of thiobarbituric acid reactive substances as well as a decrease in the serum level of endogenous ouabain, a specific ligand of the Na,K-ATPase. HH also increased the α2 Na,K-ATPase membrane abundance without changing its total protein content; the plasma membrane lipid-ordered phase did not change. In the soleus muscle, HH protected against disuse (hindlimb suspension) induced sarcolemmal depolarization. Considering that the Na,K-ATPase is critical for maintaining skeletal muscle electrogenesis and performance, these findings may have implications for countermeasures in disuse-induced pathology and hypoxic therapy.
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Rognant S, Kravtsova VV, Bouzinova EV, Melnikova EV, Krivoi II, Pierre SV, Aalkjaer C, Jepps TA, Matchkov VV. The microtubule network enables Src kinase interaction with the Na,K-ATPase to generate Ca2+ flashes in smooth muscle cells. Front Physiol 2022; 13:1007340. [PMID: 36213229 PMCID: PMC9538378 DOI: 10.3389/fphys.2022.1007340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 09/05/2022] [Indexed: 12/03/2022] Open
Abstract
Background: Several local Ca2+ events are characterized in smooth muscle cells. We have previously shown that an inhibitor of the Na,K-ATPase, ouabain induces spatially restricted intracellular Ca2+ transients near the plasma membrane, and suggested the importance of this signaling for regulation of intercellular coupling and smooth muscle cell contraction. The mechanism behind these Na,K-ATPase-dependent “Ca2+ flashes” remains to be elucidated. In addition to its conventional ion transport function, the Na,K-ATPase is proposed to contribute to intracellular pathways, including Src kinase activation. The microtubule network is important for intracellular signaling, but its role in the Na,K-ATPase-Src kinase interaction is not known. We hypothesized the microtubule network was responsible for maintaining the Na,K-ATPase-Src kinase interaction, which enables Ca2+ flashes. Methods: We characterized Ca2+ flashes in cultured smooth muscle cells, A7r5, and freshly isolated smooth muscle cells from rat mesenteric artery. Cells were loaded with Ca2+-sensitive fluorescent dyes, Calcium Green-1/AM and Fura Red/AM, for ratiometric measurements of intracellular Ca2+. The Na,K-ATPase α2 isoform was knocked down with siRNA and the microtubule network was disrupted with nocodazole. An involvement of the Src signaling was tested pharmacologically and with Western blot. Protein interactions were validated with proximity ligation assays. Results: The Ca2+ flashes were induced by micromolar concentrations of ouabain. Knockdown of the α2 isoform Na,K-ATPase abolished Ca2+ flashes, as did inhibition of tyrosine phosphorylation with genistein and PP2, and the inhibitor of the Na,K-ATPase-dependent Src activation, pNaKtide. Ouabain-induced Ca2+ flashes were associated with Src kinase activation by phosphorylation. The α2 isoform Na,K-ATPase and Src kinase colocalized in the cells. Disruption of microtubule with nocodazole inhibited Ca2+ flashes, reduced Na,K-ATPase/Src interaction and Src activation. Conclusion: We demonstrate that the Na,K-ATPase-dependent Ca2+ flashes in smooth muscle cells require an interaction between the α2 isoform Na, K-ATPase and Src kinase, which is maintained by the microtubule network.
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Affiliation(s)
- Salomé Rognant
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Violetta V. Kravtsova
- Department of General Physiology, St. Petersburg State University, St. Petersburg, Russia
| | | | | | - Igor I. Krivoi
- Department of General Physiology, St. Petersburg State University, St. Petersburg, Russia
| | - Sandrine V. Pierre
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, WV, United States
| | | | - Thomas A. Jepps
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Vladimir V. Matchkov
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- *Correspondence: Vladimir V. Matchkov,
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Skogestad J, Aronsen JM. Regulation of Cardiac Contractility by the Alpha 2 Subunit of the Na+/K+-ATPase. Front Physiol 2022; 13:827334. [PMID: 35812308 PMCID: PMC9258780 DOI: 10.3389/fphys.2022.827334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 05/16/2022] [Indexed: 11/14/2022] Open
Abstract
Cytosolic Na + concentrations regulate cardiac excitation-contraction coupling and contractility. Inhibition of the Na+/K+-ATPase (NKA) activity increases cardiac contractility by increasing cytosolic Ca2+ levels, as increased cytosolic Na+ levels are coupled to less Ca2+ extrusion and/or increased Ca2+ influx from the Na+/Ca2+-exchanger. NKA consists of one α subunit and one β subunit, with α1 and α2 being the main α isoforms in cardiomyocytes. Substantial evidence suggests that NKAα2 is the primary regulator of cardiac contractility despite being outnumbered by NKAα1 in cardiomyocytes. This review will mainly focus on differential regulation and subcellular localization of the NKAα1 and NKAα2 isoforms, and their relation to the proposed concept of subcellular gradients of Na+ in cardiomyocytes. We will also discuss the potential roles of NKAα2 in mediating cardiac hypertrophy and ventricular arrhythmias.
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Affiliation(s)
- Jonas Skogestad
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Pharmacology, Oslo University Hospital, Oslo, Norway
| | - Jan Magnus Aronsen
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Pharmacology, Oslo University Hospital, Oslo, Norway
- *Correspondence: Jan Magnus Aronsen,
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Kurtz T, Pravenec M, DiCarlo S. Mechanism-based strategies to prevent salt sensitivity and salt-induced hypertension. Clin Sci (Lond) 2022; 136:599-620. [PMID: 35452099 PMCID: PMC9069470 DOI: 10.1042/cs20210566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 03/21/2022] [Accepted: 03/30/2022] [Indexed: 12/15/2022]
Abstract
High-salt diets are a major cause of hypertension and cardiovascular (CV) disease. Many governments are interested in using food salt reduction programs to reduce the risk for salt-induced increases in blood pressure and CV events. It is assumed that reducing the salt concentration of processed foods will substantially reduce mean salt intake in the general population. However, contrary to expectations, reducing the sodium density of nearly all foods consumed in England by 21% had little or no effect on salt intake in the general population. This may be due to the fact that in England, as in other countries including the U.S.A., mean salt intake is already close to the lower normal physiologic limit for mean salt intake of free-living populations. Thus, mechanism-based strategies for preventing salt-induced increases in blood pressure that do not solely depend on reducing salt intake merit attention. It is now recognized that the initiation of salt-induced increases in blood pressure often involves a combination of normal increases in sodium balance, blood volume and cardiac output together with abnormal vascular resistance responses to increased salt intake. Therefore, preventing either the normal increases in sodium balance and cardiac output, or the abnormal vascular resistance responses to salt, can prevent salt-induced increases in blood pressure. Suboptimal nutrient intake is a common cause of the hemodynamic disturbances mediating salt-induced hypertension. Accordingly, efforts to identify and correct the nutrient deficiencies that promote salt sensitivity hold promise for decreasing population risk of salt-induced hypertension without requiring reductions in salt intake.
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Affiliation(s)
- Theodore W. Kurtz
- Department of Laboratory Medicine, University of California, San Francisco, San Francisco, CA 94017-0134, U.S.A
| | - Michal Pravenec
- Institute of Physiology, Czech Academy of Sciences, Prague 14220, Czech Republic
| | - Stephen E. DiCarlo
- Department of Physiology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI 48824, U.S.A
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12
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A real-time PCR method to genotype mutant mouse models with altered affinity for cardiotonic steroids on the Na,K-ATPase. PLoS One 2022; 17:e0267348. [PMID: 35446892 PMCID: PMC9022855 DOI: 10.1371/journal.pone.0267348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 04/06/2022] [Indexed: 12/04/2022] Open
Abstract
The highly conserved, cardiotonic steroid binding site (also termed ouabain binding site) on the primary α subunit of Na,K-ATPase plays a receptor signaling role in a range of vital cell processes and is a therapeutic target for human disease. Mouse lines with altered affinity for cardiotonic steroids on the α1 or α2 subunit isoform of Na,K-ATPase, without any change in pump activity, were developed by the late Jerry B Lingrel and are a valuable tool for studying its physiological roles and drug actions. In one model, the normally ouabain resistant α1 isoform was rendered sensitive to ouabain binding. In a second model, the normally sensitive α2 isoform was rendered resistant to ouabain binding. Additional useful models are obtained by mating these mice. To further advance their use, we developed a rapid, real-time PCR method that detects mutant alleles using specific primers and fluorescent probes. PCR is performed in fast mode with up to 15 samples processed in 40 min. The method was validated by Sanger sequencing using mice of known genotype, and by comparing results with a previous two-step method that used PCR amplification followed by gel electrophoresis. In addition, we clarified inconsistencies in published sequences, updated numbering to current reference sequences, and confirmed the continued presence of the mutations in the colony. It is expected that a wider availability of these models and a more efficient genotyping protocol will advance studies of the Na,K-ATPase and its cardiotonic steroid receptor.
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13
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Wang Q, Li N, Guo X, Huo B, Li R, Feng X, Fang Z, Zhu XH, Wang Y, Yi X, Wei X, Jiang DS. Comprehensive analysis identified a reduction in ATP1A2 mediated by ARID3A in abdominal aortic aneurysm. J Cell Mol Med 2022; 26:2866-2880. [PMID: 35441443 PMCID: PMC9097831 DOI: 10.1111/jcmm.17301] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 03/02/2022] [Accepted: 03/18/2022] [Indexed: 12/17/2022] Open
Abstract
Abdominal aortic aneurysm (AAA) is characterized by abdominal aorta dilatation and progressive structural impairment and is usually an asymptomatic and potentially lethal disease with a risk of rupture. To investigate the underlying mechanisms of AAA initiation and progression, seven AAA datasets related to human and mice were downloaded from the GEO database and reanalysed in the present study. After comprehensive bioinformatics analysis, we identified the enriched pathways associated with inflammation responses, vascular smooth muscle cell (VSMC) phenotype switching and cytokine secretion in AAA. Most importantly, we identified ATPase Na+/K+ transporting subunit alpha 2 (ATP1A2) as a key gene that was significantly decreased in AAA samples of both human and mice; meanwhile, its reduction mainly occurred in VSMCs of the aorta; this finding was validated by immunostaining and Western blot in human and mouse AAA samples. Furthermore, we explored the potential upstream transcription factors (TFs) that regulate ATP1A2 expression. We found that the TF AT‐rich interaction domain 3A (ARID3A) bound the promoter of ATP1A2 to suppress its expression. Our present study identified the ARID3A‐ATP1A2 axis as a novel pathway in the pathological processes of AAA, further elucidating the molecular mechanism of AAA and providing potential therapeutic targets for AAA.
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Affiliation(s)
- Qunhui Wang
- Division of Cardiothoracic and Vascular Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Na Li
- Division of Cardiothoracic and Vascular Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Xian Guo
- Division of Cardiothoracic and Vascular Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Bo Huo
- Division of Cardiothoracic and Vascular Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Rui Li
- Division of Cardiothoracic and Vascular Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Xin Feng
- Division of Cardiothoracic and Vascular Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Zemin Fang
- Division of Cardiothoracic and Vascular Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Xue-Hai Zhu
- Division of Cardiothoracic and Vascular Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.,Key Laboratory of Organ Transplantation, Ministry of Education, NHC Key Laboratory of Organ Transplantation, Key Laboratory of Organ Transplantation, Chinese Academy of Medical Sciences, Wuhan, Hubei, China
| | - Yixiang Wang
- Clinical medical College, Wuhan University of Science and Technology, Wuhan, Hubei, China
| | - Xin Yi
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei, China
| | - Xiang Wei
- Division of Cardiothoracic and Vascular Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.,Key Laboratory of Organ Transplantation, Ministry of Education, NHC Key Laboratory of Organ Transplantation, Key Laboratory of Organ Transplantation, Chinese Academy of Medical Sciences, Wuhan, Hubei, China
| | - Ding-Sheng Jiang
- Division of Cardiothoracic and Vascular Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.,Key Laboratory of Organ Transplantation, Ministry of Education, NHC Key Laboratory of Organ Transplantation, Key Laboratory of Organ Transplantation, Chinese Academy of Medical Sciences, Wuhan, Hubei, China
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14
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Blaustein MP, Hamlyn JM, Leenen FHH. Essential contributions of the α2-Na +/K +-ATPase ouabain binding site to cardiac remodeling. Am J Physiol Heart Circ Physiol 2021; 321:H1117-H1118. [PMID: 34842466 DOI: 10.1152/ajpheart.00548.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Mordecai P Blaustein
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - John M Hamlyn
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Frans H H Leenen
- Brain and Heart Research Group, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
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15
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Chen L, Zhang M, Wang X, Liu Y, Bian J, Yan D, Yin W. Cardiac steroid ouabain transcriptionally increases human leukocyte antigen DR expression on monocytes. Steroids 2021; 175:108915. [PMID: 34508735 DOI: 10.1016/j.steroids.2021.108915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/31/2021] [Accepted: 08/30/2021] [Indexed: 01/18/2023]
Abstract
Sepsis is a life-threatening disease characterized by acute multiple organ dysfunction and immunosuppression that is also called as immunoparalysis. Increasing evidence suggests that immunoparalysis largely contributes to the high mortality of sepsis, but the effective remedies are lacking. As an important antigen presentation molecule, human leukocyte antigen DR (HLA-DR) is remarkably down-regulated in sepsis-induced immunoparalysis, therefore, re-stimulation of HLA-DR expression is expected to be useful in reversing immunoparalysis. We previously described that ouabain, as a Na+, K+-ATPase ligand, is able to counteract immunoparalysis by regulating TH1 cytokines expression. Here, we expanded the finding that ouabain not only prevents LPS-induced down-regulation of HLA-DR on monocytes, but also transcriptionally activates HLA-DR α/β expression mediated by CIITA4, IRF1, c-Src, and Stat1 phosphorylation. Since ouabain can improve sepsis-induced immunoparalysis by multiple mechanisms, we propose that ouabain may be a promising agent in septic therapy that deserves further investigation.
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Affiliation(s)
- Lili Chen
- State Key Lab of Pharmaceutical Biotechnology, College of Life Sciences, Nanjing University, Nanjing, China
| | - Manli Zhang
- State Key Lab of Pharmaceutical Biotechnology, College of Life Sciences, Nanjing University, Nanjing, China
| | - Xiya Wang
- State Key Lab of Pharmaceutical Biotechnology, College of Life Sciences, Nanjing University, Nanjing, China
| | - Yongjian Liu
- State Key Lab of Pharmaceutical Biotechnology, College of Life Sciences, Nanjing University, Nanjing, China
| | - Jinjun Bian
- Department of Anesthesiology and Critical Care, Changhai Hospital, Naval Medical University, Shanghai, China.
| | - Dong Yan
- Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinese Medicine, China.
| | - Wu Yin
- State Key Lab of Pharmaceutical Biotechnology, College of Life Sciences, Nanjing University, Nanjing, China.
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16
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Słabiak-Błaż N, Piecha G. Endogenous Mammalian Cardiotonic Steroids-A New Cardiovascular Risk Factor?-A Mini-Review. Life (Basel) 2021; 11:life11080727. [PMID: 34440471 PMCID: PMC8398695 DOI: 10.3390/life11080727] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 07/18/2021] [Accepted: 07/20/2021] [Indexed: 12/19/2022] Open
Abstract
The role of endogenous mammalian cardiotonic steroids (CTS) in the physiology and pathophysiology of the cardiovascular system and the kidneys has interested researchers for more than 20 years. Cardiotonic steroids extracted from toads or plants, such as digitalis, have been used to treat heart disease since ancient times. CTS, also called endogenous digitalis-like factors, take part in the regulation of blood pressure and sodium homeostasis through their effects on the transport enzyme called sodium–potassium adenosine triphosphatase (Na/K-ATPase) in renal and cardiovascular tissue. In recent years, there has been increasing evidence showing deleterious effects of CTS on the structure and function of the heart, vasculature and kidneys. Understanding the role of CTS may be useful in the development of potential new therapeutic strategies.
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17
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Kravtsova VV, Krivoi II. Molecular and Functional Heterogeneity of Na,K-ATPase in the Skeletal Muscle. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s0022093021040086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Chronic Ouabain Prevents Na,K-ATPase Dysfunction and Targets AMPK and IL-6 in Disused Rat Soleus Muscle. Int J Mol Sci 2021; 22:ijms22083920. [PMID: 33920198 PMCID: PMC8069997 DOI: 10.3390/ijms22083920] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/02/2021] [Accepted: 04/08/2021] [Indexed: 12/20/2022] Open
Abstract
Sustained sarcolemma depolarization due to loss of the Na,K-ATPase function is characteristic for skeletal muscle motor dysfunction. Ouabain, a specific ligand of the Na,K-ATPase, has a circulating endogenous analogue. We hypothesized that the Na,K-ATPase targeted by the elevated level of circulating ouabain modulates skeletal muscle electrogenesis and prevents its disuse-induced disturbances. Isolated soleus muscles from rats intraperitoneally injected with ouabain alone or subsequently exposed to muscle disuse by 6-h hindlimb suspension (HS) were studied. Conventional electrophysiology, Western blotting, and confocal microscopy with cytochemistry were used. Acutely applied 10 nM ouabain hyperpolarized the membrane. However, a single injection of ouabain (1 µg/kg) prior HS was unable to prevent the HS-induced membrane depolarization. Chronic administration of ouabain for four days did not change the α1 and α2 Na,K-ATPase protein content, however it partially prevented the HS-induced loss of the Na,K-ATPase electrogenic activity and sarcolemma depolarization. These changes were associated with increased phosphorylation levels of AMP-activated protein kinase (AMPK), its substrate acetyl-CoA carboxylase and p70 protein, accompanied with increased mRNA expression of interleikin-6 (IL-6) and IL-6 receptor. Considering the role of AMPK in regulation of the Na,K-ATPase, we suggest an IL-6/AMPK contribution to prevent the effects of chronic ouabain under skeletal muscle disuse.
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19
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Lopachev AV, Lagarkova MA, Lebedeva OS, Ezhova MA, Kazanskaya RB, Timoshina YA, Khutorova AV, Akkuratov EE, Fedorova TN, Gainetdinov RR. Ouabain-Induced Gene Expression Changes in Human iPSC-Derived Neuron Culture Expressing Dopamine and cAMP-Regulated Phosphoprotein 32 and GABA Receptors. Brain Sci 2021; 11:brainsci11020203. [PMID: 33562186 PMCID: PMC7915459 DOI: 10.3390/brainsci11020203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/27/2021] [Accepted: 02/03/2021] [Indexed: 12/22/2022] Open
Abstract
Cardiotonic steroids (CTS) are specific inhibitors and endogenous ligands of a key enzyme in the CNS-the Na+, K+-ATPase, which maintains and creates an ion gradient on the plasma membrane of neurons. CTS cause the activation of various signaling cascades and changes in gene expression in neurons and other cell types. It is known that intracerebroventricular injection of cardiotonic steroid ouabain causes mania-like behavior in rodents, in part due to activation of dopamine-related signaling cascades in the dopamine and cAMP-regulated phosphoprotein 32 (DARPP-32) expressing medium spiny neurons in the striatum. Dopaminergic projections in the striatum innervate these GABAergic medium spiny neurons. The objective of this study was to assess changes in the expression of all genes in human iPSC-derived expressing DARPP-32 and GABA receptors neurons under the influence of ouabain. We noted a large number of statistically significant upregulated and downregulated genes after a 16-h incubation with non-toxic concentration (30 nM) of ouabain. These changes in the transcriptional activity were accomplished with activation of MAP-kinase ERK1/2 and transcriptional factor cAMP response element-binding protein (CREB). Thus, it can be concluded that 30 nM ouabain incubated for 16 h with human iPSC-derived expressing DARPP-32 and GABA receptors neurons activates genes associated with neuronal maturation and synapse formation, by increasing the expression of genes associated with translation, vesicular transport, and increased electron transport chain function. At the same time, the expression of genes associated with proliferation, migration, and early development of neurons decreases. These data indicate that non-toxic concentrations of ouabain may induce neuronal maturation, neurite growth, and increased synaptogenesis in dopamine-receptive GABAergic neurons, suggesting formation of plasticity and the establishment of new neuronal junctions.
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Affiliation(s)
- Alexander V. Lopachev
- Laboratory of Clinical and Experimental Neurochemistry, Research Center of Neurology, 125367 Moscow, Russia; (Y.A.T.); (A.V.K.); (T.N.F.)
- Correspondence:
| | - Maria A. Lagarkova
- Laboratory of Cell Biology, Federal Research and Clinical Center of Physical-Chemical Medicine Federal Medical Biological Agency, 119435 Moscow, Russia; (M.A.L.); (O.S.L.)
| | - Olga S. Lebedeva
- Laboratory of Cell Biology, Federal Research and Clinical Center of Physical-Chemical Medicine Federal Medical Biological Agency, 119435 Moscow, Russia; (M.A.L.); (O.S.L.)
| | - Margarita A. Ezhova
- Laboratory of Plant Genomics, Institute for Information Transmission Problems of the Russian Academy of Sciences, 127051 Moscow, Russia;
- Center of Life Sciences, Skolkovo Institute of Science and Technology, 121205 Moscow, Russia
| | - Rogneda B. Kazanskaya
- Biological Department, Saint Petersburg State University, 199034 St. Petersburg, Russia;
| | - Yulia A. Timoshina
- Laboratory of Clinical and Experimental Neurochemistry, Research Center of Neurology, 125367 Moscow, Russia; (Y.A.T.); (A.V.K.); (T.N.F.)
- Biological Department, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Anastasiya V. Khutorova
- Laboratory of Clinical and Experimental Neurochemistry, Research Center of Neurology, 125367 Moscow, Russia; (Y.A.T.); (A.V.K.); (T.N.F.)
- Biological Department, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Evgeny E. Akkuratov
- Department of Applied Physics, Royal Institute of Technology, Science for Life Laboratory, 171 65 Stockholm, Sweden;
| | - Tatiana N. Fedorova
- Laboratory of Clinical and Experimental Neurochemistry, Research Center of Neurology, 125367 Moscow, Russia; (Y.A.T.); (A.V.K.); (T.N.F.)
| | - Raul R. Gainetdinov
- Institute of Translational Biomedicine and Saint Petersburg University Hospital, Saint Petersburg State University, 199034 St. Petersburg, Russia;
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20
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Skeletal Muscle Na,K-ATPase as a Target for Circulating Ouabain. Int J Mol Sci 2020; 21:ijms21082875. [PMID: 32326025 PMCID: PMC7215781 DOI: 10.3390/ijms21082875] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 04/16/2020] [Accepted: 04/18/2020] [Indexed: 02/07/2023] Open
Abstract
While the role of circulating ouabain-like compounds in the cardiovascular and central nervous systems, kidney and other tissues in health and disease is well documented, little is known about its effects in skeletal muscle. In this study, rats were intraperitoneally injected with ouabain (0.1-10 µg/kg for 4 days) alone or with subsequent injections of lipopolysaccharide (1 mg/kg). Some rats were also subjected to disuse for 6 h by hindlimb suspension. In the diaphragm muscle, chronic ouabain (1 µg/kg) hyperpolarized resting potential of extrajunctional membrane due to specific increase in electrogenic transport activity of the 2 Na,K-ATPase isozyme and without changes in 1 and 2 Na,K-ATPase protein content. Ouabain (10-20 nM), acutely applied to isolated intact diaphragm muscle from not injected rats, hyperpolarized the membrane to a similar extent. Chronic ouabain administration prevented lipopolysaccharide-induced (diaphragm muscle) or disuse-induced (soleus muscle) depolarization of the extrajunctional membrane. No stimulation of the 1 Na,K-ATPase activity in human red blood cells, purified lamb kidney and Torpedo membrane preparations by low ouabain concentrations was observed. Our results suggest that skeletal muscle electrogenesis is subjected to regulation by circulating ouabain via the 2 Na,K-ATPase isozyme that could be important for adaptation of this tissue to functional impairment.
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21
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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.
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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
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22
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Blaustein MP, Hamlyn JM. Ouabain, endogenous ouabain and ouabain-like factors: The Na + pump/ouabain receptor, its linkage to NCX, and its myriad functions. Cell Calcium 2020; 86:102159. [PMID: 31986323 DOI: 10.1016/j.ceca.2020.102159] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 01/01/2020] [Accepted: 01/03/2020] [Indexed: 12/12/2022]
Abstract
In this brief review we discuss some aspects of the Na+ pump and its roles in mediating the effects of ouabain and endogenous ouabain (EO): i) in regulating the cytosolic Ca2+ concentration ([Ca2+]CYT) via Na/Ca exchange (NCX), and ii) in activating a number of protein kinase (PK) signaling cascades that control a myriad of cell functions. Importantly, [Ca2+]CYT and the other signaling pathways intersect at numerous points because of the influence of Ca2+ and calmodulin in modulating some steps in those other pathways. While both mechanisms operate in virtually all cells and tissues, this article focuses primarily on their functions in the cardiovascular system, the central nervous system (CNS) and the kidneys.
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Affiliation(s)
- Mordecai P Blaustein
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| | - John M Hamlyn
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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23
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Bigazzi R, Zagato L, Lanzani C, Fontana S, Messaggio E, Delli Carpini S, Citterio L, Simonini M, Brioni E, Magnaghi C, Colombo GI, Santini G, Nistri F, Cellai F, Lenti S, Bianchi S, Pertosa GB, Rocchetti MT, Papale M, Mezzolla V, Gesualdo L, Pina Concas M, Campese V, Manunta P. Hypertension in High School Students: Genetic and Environmental Factors. Hypertension 2020; 75:71-78. [DOI: 10.1161/hypertensionaha.119.13818] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hypertension and obesity in the young population are major risk factors for renal and cardiovascular events, which could arise in adulthood. A candidate-gene approach was applied in a cohort observational study, in which we collected data from 2638 high school adolescent students. Participants underwent anthropometric and blood pressure (BP) measurements, as well as saliva and urine sample collection for genomic DNA extraction and renal function evaluation, respectively. We tested whether candidate genes previously implicated in salt-sensitive hypertension in adults impact BP also among adolescents. Since inflammatory mechanisms may be involved in pathophysiology of hypertension and in endothelial dysfunction and atherosclerosis through reactive oxygen species, the baseline urinary excretion of inflammatory and oxidative stress markers in a subgroup of adolescents stratified according to
ADD1
(alpha adducin) rs4961 genotypes was assessed. Regression analysis of BP values with genetic polymorphisms, highlighted an association with a missense variant of
LSS
(lanosterol synthase, rs2254524), a gene coding for an enzyme involved in endogenous ouabain synthesis. Higher diastolic and systolic BP were associated with
LSS
A allele (
P
=0.011 and
P
=0.023, respectively). BP resulted associated with 5 more SNPs. The
KL
(klotho) rs9536314 missense variant was associated with 24 hour urinary Na
+
excretion (
P
=0.0083). Urinary protein tests showed a greater excretion of IL1β (interleukin 1β) and interleukin 10 (
P
<0.0001) in carriers of the
ADD1
rs4961 T allele. In conclusion, 3 missense gene variants already implicated in adult hypertension impact BP or Na
+
excretion among adolescents, and, together with activated pro-inflammatory pathways, might predispose to early cardiovascular damage.
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Affiliation(s)
- Roberto Bigazzi
- From the Nephrology and Dialysis Complex Operative Unit, ASL Nord Ovest Toscana, Livorno, Italy (R.B., G.S., F.N., F.C., S.B.)
| | - Laura Zagato
- Chair of Nephrology Vita-Salute University San Raffaele and Genomics of Renal Diseases and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy (L.Z., C.L., S.F., E.M., S.D.C., L.C., M.S., E.B., C.M., P.M.)
| | - Chiara Lanzani
- Chair of Nephrology Vita-Salute University San Raffaele and Genomics of Renal Diseases and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy (L.Z., C.L., S.F., E.M., S.D.C., L.C., M.S., E.B., C.M., P.M.)
| | - Simone Fontana
- Chair of Nephrology Vita-Salute University San Raffaele and Genomics of Renal Diseases and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy (L.Z., C.L., S.F., E.M., S.D.C., L.C., M.S., E.B., C.M., P.M.)
| | - Elisabetta Messaggio
- Chair of Nephrology Vita-Salute University San Raffaele and Genomics of Renal Diseases and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy (L.Z., C.L., S.F., E.M., S.D.C., L.C., M.S., E.B., C.M., P.M.)
| | - Simona Delli Carpini
- Chair of Nephrology Vita-Salute University San Raffaele and Genomics of Renal Diseases and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy (L.Z., C.L., S.F., E.M., S.D.C., L.C., M.S., E.B., C.M., P.M.)
| | - Lorena Citterio
- Chair of Nephrology Vita-Salute University San Raffaele and Genomics of Renal Diseases and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy (L.Z., C.L., S.F., E.M., S.D.C., L.C., M.S., E.B., C.M., P.M.)
| | - Marco Simonini
- Chair of Nephrology Vita-Salute University San Raffaele and Genomics of Renal Diseases and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy (L.Z., C.L., S.F., E.M., S.D.C., L.C., M.S., E.B., C.M., P.M.)
| | - Elena Brioni
- Chair of Nephrology Vita-Salute University San Raffaele and Genomics of Renal Diseases and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy (L.Z., C.L., S.F., E.M., S.D.C., L.C., M.S., E.B., C.M., P.M.)
| | - Cristiano Magnaghi
- Chair of Nephrology Vita-Salute University San Raffaele and Genomics of Renal Diseases and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy (L.Z., C.L., S.F., E.M., S.D.C., L.C., M.S., E.B., C.M., P.M.)
| | - Gualtiero Ivanoe Colombo
- Unit of Immunology and Functional Genomics, IRCCS Centro Cardiologico Monzino, Milan, Italy (G.I.C.)
| | - Giada Santini
- From the Nephrology and Dialysis Complex Operative Unit, ASL Nord Ovest Toscana, Livorno, Italy (R.B., G.S., F.N., F.C., S.B.)
| | - Francesca Nistri
- From the Nephrology and Dialysis Complex Operative Unit, ASL Nord Ovest Toscana, Livorno, Italy (R.B., G.S., F.N., F.C., S.B.)
| | - Filippo Cellai
- From the Nephrology and Dialysis Complex Operative Unit, ASL Nord Ovest Toscana, Livorno, Italy (R.B., G.S., F.N., F.C., S.B.)
| | - Salvatore Lenti
- Hypertension Center, Department of Internal Medicine, San Donato Hospital, USL Sud Est Toscana, Arezzo, Italy (S.L.)
| | - Stefano Bianchi
- From the Nephrology and Dialysis Complex Operative Unit, ASL Nord Ovest Toscana, Livorno, Italy (R.B., G.S., F.N., F.C., S.B.)
| | - Giovanni Battista Pertosa
- Area Livornese Sud, ASL Toscana Nord Ovest, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy (G.B.P., M.T.R., M.P., V.M., L.G.)
| | - Maria Teresa Rocchetti
- Area Livornese Sud, ASL Toscana Nord Ovest, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy (G.B.P., M.T.R., M.P., V.M., L.G.)
| | - Massimo Papale
- Area Livornese Sud, ASL Toscana Nord Ovest, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy (G.B.P., M.T.R., M.P., V.M., L.G.)
| | - Valeria Mezzolla
- Area Livornese Sud, ASL Toscana Nord Ovest, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy (G.B.P., M.T.R., M.P., V.M., L.G.)
| | - Loreto Gesualdo
- Area Livornese Sud, ASL Toscana Nord Ovest, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy (G.B.P., M.T.R., M.P., V.M., L.G.)
| | - Maria Pina Concas
- Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy (M.P.C.)
| | - Vito Campese
- Division of Nephrology and Hypertension, Keck School of Medicine, University of Southern California, Los Angeles, CA (V.C.)
| | - Paolo Manunta
- Chair of Nephrology Vita-Salute University San Raffaele and Genomics of Renal Diseases and Hypertension Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy (L.Z., C.L., S.F., E.M., S.D.C., L.C., M.S., E.B., C.M., P.M.)
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24
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Leenen FHH, Wang HW, Hamlyn JM. Sodium pumps, ouabain and aldosterone in the brain: A neuromodulatory pathway underlying salt-sensitive hypertension and heart failure. Cell Calcium 2019; 86:102151. [PMID: 31954234 DOI: 10.1016/j.ceca.2019.102151] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 12/15/2019] [Indexed: 02/08/2023]
Abstract
Accumulating evidence obtained over the last three decades has revealed a neuroendocrine system in the brain that mediates long term increases in blood pressure. The system involves distinct ion transport pathways including the alpha-2 isoform of the Na,K pump and epithelial sodium channels, as well as critical hormone elements such as angiotensin II, aldosterone, mineralocorticoid receptors and endogenous ouabain. Activation of this system either by circulating or central sodium ions and/or angiotensin II leads to a cascading sequence of events that begins in the hypothalamus and involves the participation of several brain nuclei including the subfornical organ, supraoptic and paraventricular nuclei and the rostral ventral medulla. Key events include heightened aldosterone synthesis and mineralocorticoid receptor activation, upregulation of epithelial sodium channels, augmented synthesis and secretion of endogenous ouabain from hypothalamic magnocellular neurons, and sustained increases in sympathetic outflow. The latter step depends upon increased production of angiotensin II and the primary amplification of angiotensin II type I receptor signaling from the paraventricular nucleus to the rostral ventral lateral medulla. The transmission of sympathetic traffic is secondarily amplified in the periphery by increased short- and long-term potentiation in sympathetic ganglia and by sustained actions of endogenous ouabain in the vascular wall that augment expression of sodium calcium exchange, increase cytosolic Ca2+ and heighten myogenic tone and contractility. Upregulation of this multi-amplifier system participates in forms of hypertension where salt, angiotensin and/or aldosterone are elevated and contributes to adverse outcomes in heart failure.
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Affiliation(s)
- Frans H H Leenen
- Brain and Heart Research Group, University of Ottawa Heart Institute, Ottawa, ON, Canada
| | - Hong-Wei Wang
- Brain and Heart Research Group, University of Ottawa Heart Institute, Ottawa, ON, Canada
| | - John M Hamlyn
- Department of Physiology, University of Maryland, Baltimore, MD, USA.
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25
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Kravtsova VV, Vilchinskaya NA, Rozlomii VL, Shenkman BS, Krivoi II. Low Ouabain Doses and AMP-Activated Protein Kinase as Factors Supporting Electrogenesis in Skeletal Muscle. BIOCHEMISTRY (MOSCOW) 2019; 84:1085-1092. [PMID: 31693468 DOI: 10.1134/s0006297919090116] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Many motor disorders are associated with depolarization of the membrane of skeletal muscle fibers due to the impaired functioning of Na,K-ATPase. Here, we studied the role of ouabain (specific Na,K-ATPase ligand) and AMP-activated protein kinase (key regulator of muscle metabolism) in the maintenance of muscle electrogenesis; the levels of these endogenous factors are directly related to the motor activity. After 4-day intraperitoneal administration of ouabain (1 µg/kg daily), a hyperpolarization of sarcolemma was registered in isolated rat diaphragm muscles due to an increase in the electrogenic activity of Na,K-ATPase. In acute experiments, addition of nanomolar ouabain concentrations to the bathing solution resulted in the muscle membrane hyperpolarization within 15 min. The effect of ouabain reversed to membrane depolarization with the increase in the external potassium concentration. It is possible that Na,K-ATPase activation by ouabain may be regulated by such factors as specific subcellular location, interaction with molecular partners, and changes in the ionic balance. Preventive administration of the AMP-activated protein kinase activator AICAR (5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside; 400 mg/kg body weight daily for 7 days) in chronic experiments resulted in the stabilization of the endplate structure and abolishment of depolarization of the rat soleus muscle membrane caused by the motor activity cessation. The obtained data can be useful for creating approaches for correction of muscle dysfunction, especially at the early stages, prior to the development of muscle atrophy.
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Affiliation(s)
- V V Kravtsova
- St. Petersburg State University, Department of General Physiology, St. Petersburg, 199034, Russia
| | - N A Vilchinskaya
- Institute of Biomedical Problems, Laboratory of Myology, Russian Academy of Sciences, Moscow, 123007, Russia
| | - V L Rozlomii
- St. Petersburg State University, Department of General Physiology, St. Petersburg, 199034, Russia
| | - B S Shenkman
- Institute of Biomedical Problems, Laboratory of Myology, Russian Academy of Sciences, Moscow, 123007, Russia
| | - I I Krivoi
- St. Petersburg State University, Department of General Physiology, St. Petersburg, 199034, Russia.
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26
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Staehr C, Hangaard L, Bouzinova EV, Kim S, Rajanathan R, Boegh Jessen P, Luque N, Xie Z, Lykke-Hartmann K, Sandow SL, Aalkjaer C, Matchkov VV. Smooth muscle Ca 2+ sensitization causes hypercontractility of middle cerebral arteries in mice bearing the familial hemiplegic migraine type 2 associated mutation. J Cereb Blood Flow Metab 2019; 39. [PMID: 29513112 PMCID: PMC6681533 DOI: 10.1177/0271678x18761712] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Familial hemiplegic migraine type 2 (FHM2) is associated with inherited point-mutations in the Na,K-ATPase α2 isoform, including G301R mutation. We hypothesized that this mutation affects specific aspects of vascular function, and thus compared cerebral and systemic arteries from heterozygote mice bearing the G301R mutation (Atp1a2+/-G301R) with wild type (WT). Middle cerebral (MCA) and mesenteric small artery (MSA) function was compared in an isometric myograph. Cerebral blood flow was assessed with Laser speckle analysis. Intracellular Ca2+ and membrane potential were measured simultaneously. Protein expression was semi-quantified by immunohistochemistry. Protein phosphorylation was analysed by Western blot. MSA from Atp1a2+/-G301R and WT showed similar contractile responses. The Atp1a2+/-G301R MCA constricted stronger to U46619, endothelin and potassium compared to WT. This was associated with an increased depolarization, although the Ca2+ change was smaller than in WT. The enhanced constriction of Atp1a2+/-G301R MCA was associated with increased cSrc activation, stronger sensitization to [Ca2+]i and increased MYPT1 phosphorylation. These differences were abolished by cSrc inhibition. Atp1a2+/-G301R mice had reduced resting blood flow through MCA in comparison with WT mice. FHM2-associated mutation leads to elevated contractility of MCA due to sensitization of the contractile machinery to Ca2+, which is mediated via Na,K-ATPase/Src-kinase/MYPT1 signalling.
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Affiliation(s)
| | - Lise Hangaard
- 1 Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Sukhan Kim
- 1 Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | | | - Nathan Luque
- 2 Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Queensland, Australia
| | - Zijian Xie
- 3 Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, WV, USA
| | | | - Shaun L Sandow
- 2 Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Queensland, Australia
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27
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Lu J, Wang HW, Ahmad M, Keshtkar-Jahromi M, Blaustein MP, Hamlyn JM, Leenen FHH. Central and peripheral slow-pressor mechanisms contributing to Angiotensin II-salt hypertension in rats. Cardiovasc Res 2019; 114:233-246. [PMID: 29126194 DOI: 10.1093/cvr/cvx214] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 11/07/2017] [Indexed: 12/17/2022] Open
Abstract
Aims High salt intake markedly enhances hypertension induced by angiotensin II (Ang II). We explored central and peripheral slow-pressor mechanisms which may be activated by Ang II and salt. Methods and results In protocol I, Wistar rats were infused subcutaneously with low-dose Ang II (150 ng/kg/min) and fed regular (0.4%) or high salt (2%) diet for 14 days. In protocol II, Ang II-high salt was combined with intracerebroventricular infusion of mineralocorticoid receptor (MR) blockers (eplerenone, spironolactone), epithelial sodium channel (ENaC) blocker (benzamil), angiotensin II type 1 receptor (AT1R) blocker (losartan) or vehicles. Ang II alone raised mean arterial pressure (MAP) ∼10 mmHg, but Ang II-high salt increased MAP ∼50 mmHg. Ang II-high salt elevated plasma corticosterone, aldosterone and endogenous ouabain but not Ang II alone. Both Ang II alone and Ang II-high salt increased mRNA and protein expression of CYP11B2 (aldosterone synthase gene) in the adrenal cortex but not of CYP11B1 (11-β-hydroxylase gene). In the aorta, Ang II-high salt increased sodium-calcium exchanger-1 (NCX1) protein. The Ang II-high salt induced increase in MAP was largely prevented by central infusion of MR blockers, benzamil or losartan. Central blockades significantly lowered plasma aldosterone and endogenous ouabain and markedly decreased Ang II-high salt induced CYP11B2 mRNA expression in the adrenal cortex and NCX1 protein in the aorta. Conclusion These results suggest that in Ang II-high salt hypertension, MR-ENaC-AT1R signalling in the brain increases circulating aldosterone and endogenous ouabain, and arterial NCX1. These factors can amplify blood pressure responses to centrally-induced sympatho-excitation and thereby contribute to severe hypertension.
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Affiliation(s)
- Jiao Lu
- Brain and Heart Research Group, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, ON K1Y 4W7, Canada
| | - Hong-Wei Wang
- Brain and Heart Research Group, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, ON K1Y 4W7, Canada
| | - Monir Ahmad
- Brain and Heart Research Group, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, ON K1Y 4W7, Canada
| | - Marzieh Keshtkar-Jahromi
- Brain and Heart Research Group, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, ON K1Y 4W7, Canada.,Department of Physiology, University of Maryland School of Medicine, 655 West Baltimore S, Baltimore, MD 21201, USA
| | - Mordecai P Blaustein
- Department of Physiology, University of Maryland School of Medicine, 655 West Baltimore S, Baltimore, MD 21201, USA.,Department of Medicine, University of Maryland School of Medicine, 655 West Baltimore S, Baltimore, MD 21201, USA
| | - John M Hamlyn
- Department of Physiology, University of Maryland School of Medicine, 655 West Baltimore S, Baltimore, MD 21201, USA
| | - Frans H H Leenen
- Brain and Heart Research Group, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, ON K1Y 4W7, Canada
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28
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Kurtz TW, DiCarlo SE, Pravenec M, Ježek F, Šilar J, Kofránek J, Morris RC. Testing Computer Models Predicting Human Responses to a High-Salt Diet. Hypertension 2019; 72:1407-1416. [PMID: 30571226 DOI: 10.1161/hypertensionaha.118.11552] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Recently, mathematical models of human integrative physiology, derived from Guyton's classic 1972 model of the circulation, have been used to investigate potential mechanistic abnormalities mediating salt sensitivity and salt-induced hypertension. We performed validation testing of 2 of the most evolved derivatives of Guyton's 1972 model, Quantitative Cardiovascular Physiology-2005 and HumMod-3.0.4, to determine whether the models accurately predict sodium balance and hemodynamic responses of normal subjects to increases in salt intake within the real-life range of salt intake in humans. Neither model, nor the 1972 Guyton model, accurately predicts the usual changes in sodium balance, cardiac output, and systemic vascular resistance that normally occur in response to clinically realistic increases in salt intake. Furthermore, although both contemporary models are extensions of the 1972 Guyton model, testing revealed major inconsistencies between model predictions with respect to sodium balance and hemodynamic responses of normal subjects to short-term and long-term salt loading. These results demonstrate significant limitations with the hypotheses inherent in the Guyton models regarding the usual regulation of sodium balance, cardiac output, and vascular resistance in response to increased salt intake in normal salt-resistant humans. Accurate understanding of the normal responses to salt loading is a prerequisite for accurately establishing abnormal responses to salt loading. Accordingly, the present results raise concerns about the interpretation of studies of salt sensitivity with the various Guyton models. These findings indicate a need for continuing development of alternative models that incorporate mechanistic concepts of blood pressure regulation fundamentally different from those in the 1972 Guyton model and its contemporary derivatives.
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Affiliation(s)
- Theodore W Kurtz
- From the Department of Laboratory Medicine (T.W.K.), School of Medicine, University of California, San Francisco
| | - Stephen E DiCarlo
- Department of Physiology, College of Osteopathic Medicine, Michigan State University, East Lansing (S.E.D.)
| | - Michal Pravenec
- Institute of Physiology of the Czech Academy of Sciences, Prague (M.P.)
| | - Filip Ježek
- Department of Cybernetics, Czech Technical University in Prague (F.J.).,Department of Pathophysiology, 1st Faculty of Medicine, Charles University, Prague (F.J., J.S., J.K.)
| | - Jan Šilar
- Department of Pathophysiology, 1st Faculty of Medicine, Charles University, Prague (F.J., J.S., J.K.)
| | - Jiří Kofránek
- Department of Pathophysiology, 1st Faculty of Medicine, Charles University, Prague (F.J., J.S., J.K.)
| | - R Curtis Morris
- Department of Medicine (R.C.M.), School of Medicine, University of California, San Francisco
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HIF1 α-Induced Glycolysis in Macrophage Is Essential for the Protective Effect of Ouabain during Endotoxemia. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:7136585. [PMID: 31182997 PMCID: PMC6512009 DOI: 10.1155/2019/7136585] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 03/09/2019] [Accepted: 03/24/2019] [Indexed: 12/16/2022]
Abstract
Ouabain, a steroid binding to the Na+/K+-ATPase, has several pharmacological effects. In addition to the recognized effects of blood pressure, there is more convincing evidence suggesting that ouabain is involved in immunologic functions and inflammation. Hypoxia-inducible factor 1α (HIF-1α) is a metabolic regulator which plays a considerable role in immune responses. Previous studies had shown that HIF-1α-induced glycolysis results in functional reshaping in macrophages. In this study, we investigated the role of glycolytic pathway activation in the anti-inflammatory effect of ouabain. We found that ouabain is involved in anti-inflammatory effects both in vivo and in vitro. Additionally, ouabain can inhibit LPS-induced upregulation of GLUT1 and HK2 at the transcriptional level. GM-CSF pretreatment almost completely reversed the inhibitory effect of ouabain on LPS-induced release of proinflammatory cytokines. Alterations in glycolytic pathway activation were required for the anti-inflammatory effect of ouabain. Ouabain can significantly inhibit the upregulation of HIF-1α at the protein level. Our results also revealed that the overexpression of HIF-1α can reverse the anti-inflammatory effect of ouabain. Thus, we conclude that the HIF-1α-dependent glycolytic pathway is essential for the anti-inflammatory effect of ouabain.
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30
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Staehr C, Rajanathan R, Matchkov VV. Involvement of the Na + ,K + -ATPase isoforms in control of cerebral perfusion. Exp Physiol 2019; 104:1023-1028. [PMID: 30768809 DOI: 10.1113/ep087519] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 02/11/2019] [Indexed: 12/11/2022]
Abstract
NEW FINDINGS What is the topic of this review? In this review, we consider the role of the Na+ ,K+ -ATPase in cerebrovascular function and how it might be changed in familial hemiplegic migraine type 2 (FHM2). The primary focus is involvement of the Na+ ,K+ -ATPase isoforms in regulation of cerebrovascular tone. What advances does it highlight? In this review, we discuss three overall distinct mechanisms whereby the Na+ ,K+ -ATPase might be capable of regulating cerebrovascular tone. Furthermore, we discuss how changes in the Na+ ,K+ -ATPase in cerebral arteries might affect brain perfusion and thereby be involved in the pathology of FHM2. ABSTRACT Familial hemiplegic migraine type 2 (FHM2) has been characterized by biphasic changes in cerebral blood flow during a migraine attack, with initial hypoperfusion followed by abnormal hyperperfusion of the affected hemisphere. We suggested that FHM2-associated loss-of-function mutation(s) in the Na+ ,K+ -ATPase α2 isoform might be responsible for these biphasic changes in several ways. We found that reduced expression of the α2 isoform leads to sensitization of the contractile machinery to [Ca2+ ]i via Src kinase-dependent signal transduction. This change in sensitivity might be the underlying mechanism for both abnormally potentiated vasoconstriction and exaggerated vasorelaxation. Moreover, the functional significance of the Na+ ,K+ -ATPase α2 isoform in astrocytes provides for the possibility of elevated extracellular potassium signalling from astrocytic endfeet to the vascular wall in neurovascular coupling.
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Affiliation(s)
- Christian Staehr
- Department of Biomedicine, Health, Aarhus University, Aarhus C, Denmark
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31
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Abstract
The Na,K-ATPase is an enzyme essential for ion homeostasis in all cells. Over the last decades, it has been well-established that in addition to the transport of Na+/K+ over the cell membrane, the Na,K-ATPase acts as a receptor transducing humoral signals intracellularly. It has been suggested that ouabain-like compounds serve as endogenous modulators of this Na,K-ATPase signal transduction. The molecular mechanisms underlying Na,K-ATPase signaling are complicated and suggest the confluence of divergent biological pathways. This review discusses recent updates on the Na,K-ATPase signaling pathways characterized or suggested in vascular smooth muscle cells. The conventional view on this signaling is based on a microdomain structure where the Na,K-ATPase controls the Na,Ca-exchanger activity via modulation of intracellular Na+ in the spatially restricted submembrane space. This, in turn, affects intracellular Ca2+ and Ca2+ load in the sarcoplasmic reticulum leading to modulation of contractility as well as gene expression. An ion-transport-independent signal transduction from the Na,K-ATPase is based on molecular interactions. This was primarily characterized in other cell types but recently also demonstrated in vascular smooth muscles. The downstream signaling from the Na,K-ATPase includes Src and phosphatidylinositol-4,5-bisphosphate 3 kinase signaling pathways and generation of reactive oxygen species. Moreover, in vascular smooth muscle cells the interaction between the Na,K-ATPase and proteins responsible for Ca2+ homeostasis, e.g., phospholipase C and inositol triphosphate receptors, contributes to an integration of the signaling pathways. Recent update on the Na,K-ATPase dependent intracellular signaling and the significance for physiological functions and pathophysiological changes are discussed in this review.
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32
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Zhang J, Wang Y, Chen L, Wier WG, Blaustein MP. Na +/Ca 2+ exchanger overexpression in smooth muscle augments cytosolic Ca 2+ in femoral arteries of living mice. Am J Physiol Heart Circ Physiol 2019; 316:H298-H310. [PMID: 30461304 PMCID: PMC6397384 DOI: 10.1152/ajpheart.00185.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 11/05/2018] [Accepted: 11/15/2018] [Indexed: 11/22/2022]
Abstract
Plasma membrane Na+/Ca2+ exchanger-1 (NCX1) helps regulate the cytosolic Ca2+ concentration ([Ca2+]CYT) in arterial myocytes. NCX1 mediates both Ca2+ entry and exit and tends to promote net Ca2+ entry in partially constricted arteries. Mean blood pressure (telemetry) is elevated by ≈10 mmHg in transgenic (TG) mice that overexpress NCX1 specifically in smooth muscle. We tested the hypothesis that NCX1 overexpression mediates Ca2+ gain and elevated [Ca2+]CYT in exposed femoral arteries that also express the Ca2+ biosensor exogenous myosin light chain kinase. [Ca2+]CYT and the NCX1-dependent (SEA0400-sensitive) component, ≈15% of total basal constriction in controls, were increased in TG arteries, but constrictions to phenylephrine and ANG II were comparable in TG and control arteries. Normalized phenylephrine dose-response curves and constriction to 30 and 300 ng/kg iv ANG II were virtually identical in control and TG arteries. ANG II-evoked constrictions, superimposed on elevated basal tone, accounted for the larger blood pressure responses to ANG II in TG arteries. TG and control mouse arteries fit the same pCa-constriction relationship over a wide range of pCa (≈125-500 nM). Vasodilation to acetylcholine, normalized to passive diameter, was also comparable in TG and control arteries, implying normal endothelial function. TG artery Na+ nitroprusside (nitric oxide donor)-induced dilations were, however, shifted to lower Na+ nitroprusside concentrations, indicating that TG myocyte vasodilator mechanisms were augmented. Maximum arterial dilation was comparable in TG and control mice, although passive diameter was ≈6-7% smaller in TG mice. The changes in TG arteries were apparently largely functional rather than structural, despite the congenital hypertension. NEW & NOTEWORTHY Smooth muscle Na+/Ca2+ exchanger-1 transgene overexpression (TG mice) increases femoral artery basal cytosolic Ca2+ concentration ([Ca2+]CYT) and tone in vivo and raises blood pressure. Arterial constriction to phenylephrine and angiotensin II are normal but superimposed on the augmented basal [Ca2+]CYT and tone (constriction) in TG mouse arteries. Similar effects in resistance arteries would explain the elevated blood pressure. Acetylcholine-induced vasodilation is unimpaired, implying a normal endothelium, but TG arteries are hypersensitive to sodium nitroprusside.
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Affiliation(s)
- Jin Zhang
- Department of Physiology, University of Maryland School of Medicine , Baltimore, Maryland
| | - Youhua Wang
- Department of Physiology, University of Maryland School of Medicine , Baltimore, Maryland
- Department of Physical Education, Shaanxi Normal University , Xi'an, Shaanxi , China
| | - Ling Chen
- Department of Physiology, University of Maryland School of Medicine , Baltimore, Maryland
- Department of Medicine, University of Maryland School of Medicine , Baltimore, Maryland
| | - W Gil Wier
- Department of Physiology, University of Maryland School of Medicine , Baltimore, Maryland
| | - Mordecai P Blaustein
- Department of Physiology, University of Maryland School of Medicine , Baltimore, Maryland
- Department of Medicine, University of Maryland School of Medicine , Baltimore, Maryland
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33
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The Myometrium: From Excitation to Contractions and Labour. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1124:233-263. [PMID: 31183830 DOI: 10.1007/978-981-13-5895-1_10] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
We start by describing the functions of the uterus, its structure, both gross and fine, innervation and blood supply. It is interesting to note the diversity of the female's reproductive tract between species and to remember it when working with different animal models. Myocytes are the overwhelming cell type of the uterus (>95%) and our focus. Their function is to contract, and they have an intrinsic pacemaker and rhythmicity, which is modified by hormones, stretch, paracrine factors and the extracellular environment. We discuss evidence or not for pacemaker cells in the uterus. We also describe the sarcoplasmic reticulum (SR) in some detail, as it is relevant to calcium signalling and excitability. Ion channels, including store-operated ones, their contributions to excitability and action potentials, are covered. The main pathway to excitation is from depolarisation opening voltage-gated Ca2+ channels. Much of what happens downstream of excitability is common to other smooth muscles, with force depending upon the balance of myosin light kinase and phosphatase. Mechanisms of maintaining Ca2+ balance within the myocytes are discussed. Metabolism, and how it is intertwined with activity, blood flow and pH, is covered. Growth of the myometrium and changes in contractile proteins with pregnancy and parturition are also detailed. We finish with a description of uterine activity and why it is important, covering progression to labour as well as preterm and dysfunctional labours. We conclude by highlighting progress made and where further efforts are required.
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34
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Schneditz G, Elias JE, Pagano E, Zaeem Cader M, Saveljeva S, Long K, Mukhopadhyay S, Arasteh M, Lawley TD, Dougan G, Bassett A, Karlsen TH, Kaser A, Kaneider NC. GPR35 promotes glycolysis, proliferation, and oncogenic signaling by engaging with the sodium potassium pump. Sci Signal 2019; 12:12/562/eaau9048. [PMID: 30600262 DOI: 10.1126/scisignal.aau9048] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The sodium potassium pump (Na/K-ATPase) ensures the electrochemical gradient of a cell through an energy-dependent process that consumes about one-third of regenerated ATP. We report that the G protein-coupled receptor GPR35 interacted with the α chain of Na/K-ATPase and promotes its ion transport and Src signaling activity in a ligand-independent manner. Deletion of Gpr35 increased baseline Ca2+ to maximal levels and reduced Src activation and overall metabolic activity in macrophages and intestinal epithelial cells (IECs). In contrast, a common T108M polymorphism in GPR35 was hypermorphic and had the opposite effects to Gpr35 deletion on Src activation and metabolic activity. The T108M polymorphism is associated with ulcerative colitis and primary sclerosing cholangitis, inflammatory diseases with a high cancer risk. GPR35 promoted homeostatic IEC turnover, whereas Gpr35 deletion or inhibition by a selective pepducin prevented inflammation-associated and spontaneous intestinal tumorigenesis in mice. Thus, GPR35 acts as a central signaling and metabolic pacesetter, which reveals an unexpected role of Na/K-ATPase in macrophage and IEC biology.
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Affiliation(s)
- Georg Schneditz
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK.,Norwegian PSC Research Center, Department of Transplantation Medicine and Institute of Clinical Medicine, Oslo University Hospital and University of Oslo, 0027 Oslo, Norway
| | - Joshua E Elias
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Ester Pagano
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK.,Department of Pharmacy, University of Naples Federico II, 80131 Naples, Italy
| | - M Zaeem Cader
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Svetlana Saveljeva
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Kathleen Long
- Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK
| | - Subhankar Mukhopadhyay
- Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK.,MRC Centre for Transplantation, Peter Gorer Department of Immunobiology, School of Immunology & Microbial Sciences, King's College London, London SE1 9RT, UK
| | | | | | - Gordon Dougan
- Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK
| | | | - Tom H Karlsen
- Norwegian PSC Research Center, Department of Transplantation Medicine and Institute of Clinical Medicine, Oslo University Hospital and University of Oslo, 0027 Oslo, Norway
| | - Arthur Kaser
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Nicole C Kaneider
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK.
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Kurtz TW, DiCarlo SE, Pravenec M, Morris RC. Changing views on the common physiologic abnormality that mediates salt sensitivity and initiation of salt-induced hypertension: Japanese research underpinning the vasodysfunction theory of salt sensitivity. Hypertens Res 2018; 42:6-18. [DOI: 10.1038/s41440-018-0122-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 07/26/2018] [Accepted: 07/27/2018] [Indexed: 12/24/2022]
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Bouzinova EV, Hangaard L, Staehr C, Mazur A, Ferreira A, Chibalin AV, Sandow SL, Xie Z, Aalkjaer C, Matchkov VV. The α2 isoform Na,K-ATPase modulates contraction of rat mesenteric small artery via cSrc-dependent Ca 2+ sensitization. Acta Physiol (Oxf) 2018; 224:e13059. [PMID: 29480968 DOI: 10.1111/apha.13059] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Revised: 02/06/2018] [Accepted: 02/16/2018] [Indexed: 12/11/2022]
Abstract
AIMS The Na,K-ATPase is involved in a large number of regulatory activities including cSrc-dependent signalling. Upon inhibition of the Na,K-ATPase with ouabain, cSrc activation is shown to occur in many cell types. This study tests the hypothesis that acute potentiation of agonist-induced contraction by ouabain is mediated through Na,K-ATPase-cSrc signalling-dependent sensitization of vascular smooth muscle cells to Ca2+ . METHODS Agonist-induced rat mesenteric small artery contraction was examined in vitro under isometric conditions and in vivo in anaesthetized rats. Arterial wall tension and [Ca2+ ]i in vascular smooth muscle cells were measured simultaneously. Changes in cSrc and myosin phosphatase targeting protein 1 (MYPT1) phosphorylation were analysed by Western blot. Protein expression was examined with immunohistochemistry. The α1 and α2 isoforms of the Na,K-ATPase were transiently downregulated by siRNA transfection in vivo. RESULTS Ten micromolar ouabain, but not digoxin, potentiated contraction to noradrenaline. This effect was not endothelium-dependent. Ouabain sensitized smooth muscle cells to Ca2+ , and this was associated with increased phosphorylation of cSrc and MYPT1. Inhibition of tyrosine kinase by genistein, PP2 or pNaKtide abolished the potentiating effect of ouabain on arterial contraction and Ca2+ sensitization. Downregulation of the Na,K-ATPase α2 isoform made arterial contraction insensitive to ouabain and tyrosine kinase inhibition. CONCLUSION Data suggest that micromolar ouabain potentiates agonist-induced contraction of rat mesenteric small artery via Na,K-ATPase-dependent cSrc activation, which increases Ca2+ sensitization of vascular smooth muscle cells by MYPT1 phosphorylation. This mechanism may be critical for acute control of vascular tone.
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Affiliation(s)
- E. V. Bouzinova
- Department of Biomedicine; Aarhus University; Aarhus C Denmark
| | - L. Hangaard
- Department of Biomedicine; Aarhus University; Aarhus C Denmark
| | - C. Staehr
- Department of Biomedicine; Aarhus University; Aarhus C Denmark
| | - A. Mazur
- Department of Biomedicine; Aarhus University; Aarhus C Denmark
| | - A. Ferreira
- Department of Biomedicine; Aarhus University; Aarhus C Denmark
| | - A. V. Chibalin
- Department of Molecular Medicine and Surgery; Integrative Physiology; Karolinska Institutet; Stockholm Sweden
| | - S. L. Sandow
- Faculty of Science, Health, Education and Engineering; University of the Sunshine Coast; Maroochydore Qld Australia
| | - Z. Xie
- Marshall Institute for Interdisciplinary Research; Marshall University; Huntington WV USA
| | - C. Aalkjaer
- Department of Biomedicine; Aarhus University; Aarhus C Denmark
| | - V. V. Matchkov
- Department of Biomedicine; Aarhus University; Aarhus C Denmark
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The Na,K-ATPase-Dependent Src Kinase Signaling Changes with Mesenteric Artery Diameter. Int J Mol Sci 2018; 19:ijms19092489. [PMID: 30142894 PMCID: PMC6164810 DOI: 10.3390/ijms19092489] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 08/17/2018] [Accepted: 08/21/2018] [Indexed: 01/09/2023] Open
Abstract
Inhibition of the Na,K-ATPase by ouabain potentiates vascular tone and agonist-induced contraction. These effects of ouabain varies between different reports. In this study, we assessed whether the pro-contractile effect of ouabain changes with arterial diameter and the molecular mechanism behind it. Rat mesenteric small arteries of different diameters (150–350 µm) were studied for noradrenaline-induced changes of isometric force and intracellular Ca2+ in smooth muscle cells. These functional changes were correlated to total Src kinase and Src phosphorylation assessed immunohistochemically. High-affinity ouabain-binding sites were semi-quantified with fluorescent ouabain. We found that potentiation of noradrenaline-sensitivity by ouabain correlates positively with an increase in arterial diameter. This was not due to differences in intracellular Ca2+ responses but due to sensitization of smooth muscle cell contractile machinery to Ca2+. This was associated with ouabain-induced Src activation, which increases with increasing arterial diameter. Total Src expression was similar in arteries of different diameters but the density of high-affinity ouabain binding sites increased with increasing arterial diameters. We suggested that ouabain binding induces more Src kinase activity in mesenteric small arteries with larger diameter leading to enhanced sensitization of the contractile machinery to Ca2+.
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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.
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Role of endogenous digitalis-like factors in the clinical manifestations of severe preeclampsia: a sytematic review. Clin Sci (Lond) 2018; 132:1215-1242. [PMID: 29930141 DOI: 10.1042/cs20171499] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 04/26/2018] [Accepted: 05/08/2018] [Indexed: 12/18/2022]
Abstract
Endogenous digitalis-like factor(s), originally proposed as a vasoconstrictor natriuretic hormone, was discovered in fetal and neonatal blood accidentally because it cross-reacts with antidigoxin antibodies (ADAs). Early studies using immunoassays with ADA identified the digoxin-like immuno-reactive factor(s) (EDLF) in maternal blood as well, and suggested it originated in the feto-placental unit. Mammalian digoxin-like factors have recently been identified as at least two classes of steroid compounds, plant derived ouabain (O), and several toad derived bufodienolides, most prominent being marinobufagenin (MBG). A synthetic pathway for MBG has been identified in mammalian placental tissue. Elevated maternal and fetal EDLF, O and MBG have been demonstrated in preeclampsia (PE), and inhibition of red cell membrane sodium, potassium ATPase (Na, K ATPase (NKA)) by EDLF is reversed by ADA fragments (ADA-FAB). Accordingly, maternal administration of a commercial ADA-antibody fragment (FAB) was tested in several anecdotal cases of PE, and two, small randomized, prospective, double-blind clinical trials. In the first randomized trial, ADA-FAB was administered post-partum, in the second antepartum. In the post-partum trial, ADA-FAB reduced use of antihypertensive drugs. In the second trial, there was no effect of ADA-FAB on blood pressure, but the fall in maternal creatinine clearance (CrCl) was prevented. In a secondary analysis using the pre-treatment maternal level of circulating Na, K ATPase (NKA) inhibitory activity (NKAI), ADA-FAB reduced the incidence of pulmonary edema and, unexpectedly, that of severe neonatal intraventricular hemorrhage (IVH). The fall in CrCl in patients given placebo was proportional to the circulating level of NKAI. The implications of these findings on the pathophysiology of the clinical manifestations PE are discussed, and a new model of the respective roles of placenta derived anti-angiogenic (AAG) factors (AAGFs) and EDLF is proposed.
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40
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The American Heart Association Scientific Statement on salt sensitivity of blood pressure: Prompting consideration of alternative conceptual frameworks for the pathogenesis of salt sensitivity? J Hypertens 2018. [PMID: 28650918 DOI: 10.1097/hjh.0000000000001458] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
: Recently, the American Heart Association (AHA) published a scientific statement on salt sensitivity of blood pressure which emphasized a decades old conceptual framework for the pathogenesis of this common disorder. Here we examine the extent to which the conceptual framework for salt sensitivity emphasized in the AHA Statement accommodates contemporary findings and views of the broader scientific community on the pathogenesis of salt sensitivity. In addition, we highlight alternative conceptual frameworks and important contemporary theories of salt sensitivity that are little discussed in the AHA Statement. We suggest that greater consideration of conceptual frameworks and theories for salt sensitivity beyond those emphasized in the AHA Statement may help to advance understanding of the pathogenesis of salt-induced increases in blood pressure and, in consequence, may lead to improved approaches to preventing and treating this common disorder.
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The pivotal role of renal vasodysfunction in salt sensitivity and the initiation of salt-induced hypertension. Curr Opin Nephrol Hypertens 2018; 27:83-92. [DOI: 10.1097/mnh.0000000000000394] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Hodes A, Lifschytz T, Rosen H, Cohen Ben-Ami H, Lichtstein D. Reduction in endogenous cardiac steroids protects the brain from oxidative stress in a mouse model of mania induced by amphetamine. Brain Res Bull 2018; 137:356-362. [PMID: 29374602 DOI: 10.1016/j.brainresbull.2018.01.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/10/2018] [Accepted: 01/19/2018] [Indexed: 02/08/2023]
Abstract
OBJECTIVES Bipolar disorder (BD) is a severe mental illness characterized by episodes of mania and depression. Numerous studies have implicated the involvement of endogenous cardiac steroids (CS), and their receptor, Na+, K+ -ATPase, in BD. The aim of the present study was to examine the role of brain oxidative stress in the CS-induced behavioral effects in mice. METHODS Amphetamine (AMPH)-induced hyperactivity, assessed in the open-field test, served as a model for manic-like behavior in mice. A reduction in brain CS was obtained by specific and sensitive anti-ouabain antibodies. The level of oxidative stress was tested in the hippocampus and frontal cortex by measuring the activity of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), as well as the levels of antioxidant non-protein thiols (NPSH) and oxidative damage biomarkers thiobarbituric acid reactive substances (TBARS) and protein carbonyl (PC). RESULTS AMPH administration resulted in a marked hyperactivity and increased oxidative stress, as manifested by increased SOD activity, decreased activities of CAT and GPx, reduced levels of NPSH and increased levels of TBARS and PC. The administration of anti-ouabain antibodies, which reduced the AMPH-induced hyperactivity, protected against the concomitant oxidative stress in the brain. CONCLUSIONS Our results demonstrate that oxidative stress participates in the effects of endogenous CS on manic-like behavior induced by AMPH. These finding support the notion that CS and oxidative stress may be associated with the pathophysiology of mania and BD.
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Affiliation(s)
- Anastasia Hodes
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Tzuri Lifschytz
- Department of Psychiatry, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Haim Rosen
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Hagit Cohen Ben-Ami
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - David Lichtstein
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
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Cardiovascular Disease: An Introduction. BIOMATHEMATICAL AND BIOMECHANICAL MODELING OF THE CIRCULATORY AND VENTILATORY SYSTEMS 2018. [PMCID: PMC7123129 DOI: 10.1007/978-3-319-89315-0_1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Cardiovascular disease (CVD) is a collective term designating all types of affliction affecting the blood circulatory system, including the heart and vasculature, which, respectively, displaces and conveys the blood.
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Cavalcante-Silva LHA, Lima ÉDA, Carvalho DCM, de Sales-Neto JM, Alves AKDA, Galvão JGFM, da Silva JSDF, Rodrigues-Mascarenhas S. Much More than a Cardiotonic Steroid: Modulation of Inflammation by Ouabain. Front Physiol 2017; 8:895. [PMID: 29176951 PMCID: PMC5686084 DOI: 10.3389/fphys.2017.00895] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 10/24/2017] [Indexed: 12/22/2022] Open
Abstract
Since the discovery of ouabain as a cardiotonic steroid hormone present in higher mammals, research about it has progressed rapidly and several of its physiological and pharmacological effects have been described. Ouabain can behave as a stress hormone and adrenal cortex is its main source. Direct effects of ouabain are originated due to the binding to its receptor, the Na+/K+-ATPase, on target cells. This interaction can promote Na+ transport blockade or even activation of signaling transduction pathways (e.g., EGFR/Src-Ras-ERK pathway activation), independent of ion transport. Besides the well-known effect of ouabain on the cardiovascular system and blood pressure control, compelling evidence indicates that ouabain regulates a number of immune functions. Inflammation is a tightly coordinated immunological function that is also affected by ouabain. Indeed, this hormone can modulate many inflammatory events such as cell migration, vascular permeability, and cytokine production. Moreover, ouabain also interferes on neuroinflammation. However, it is not clear how ouabain controls these events. In this brief review, we summarize the updates of ouabain effect on several aspects of peripheral and central inflammation, bringing new insights into ouabain functions on the immune system.
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Affiliation(s)
- Luiz H A Cavalcante-Silva
- Programa de Pós-Graduação em Produtos Naturais e Sintéticos Bioativos, Laboratório de Imunobiotecnologia, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Brazil
| | - Éssia de Almeida Lima
- Programa de Pós-Graduação em Biotecnologia, Laboratório de Imunobiotecnologia, Centro de Biotecnologia, Universidade Federal da Paraíba, João Pessoa, Brazil
| | - Deyse C M Carvalho
- Programa Multicêntrico de Pós-graduação em Ciências Fisiológicas, Laboratório de Imunobiotecnologia, Centro de Biotecnologia, Universidade Federal da Paraíba, João Pessoa, Brazil
| | - José M de Sales-Neto
- Programa de Pós-Graduação em Produtos Naturais e Sintéticos Bioativos, Laboratório de Imunobiotecnologia, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Brazil
| | - Anne K de Abreu Alves
- Programa de Pós-Graduação em Biotecnologia, Laboratório de Imunobiotecnologia, Centro de Biotecnologia, Universidade Federal da Paraíba, João Pessoa, Brazil
| | - José G F M Galvão
- Programa de Pós-Graduação em Produtos Naturais e Sintéticos Bioativos, Laboratório de Imunobiotecnologia, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Brazil
| | - Juliane S de França da Silva
- Programa de Pós-Graduação em Produtos Naturais e Sintéticos Bioativos, Laboratório de Imunobiotecnologia, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Brazil
| | - Sandra Rodrigues-Mascarenhas
- Programa de Pós-Graduação em Produtos Naturais e Sintéticos Bioativos, Laboratório de Imunobiotecnologia, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Brazil.,Programa de Pós-Graduação em Biotecnologia, Laboratório de Imunobiotecnologia, Centro de Biotecnologia, Universidade Federal da Paraíba, João Pessoa, Brazil.,Programa Multicêntrico de Pós-graduação em Ciências Fisiológicas, Laboratório de Imunobiotecnologia, Centro de Biotecnologia, Universidade Federal da Paraíba, João Pessoa, Brazil
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Blaustein MP. The pump, the exchanger, and the holy spirit: origins and 40-year evolution of ideas about the ouabain-Na + pump endocrine system. Am J Physiol Cell Physiol 2017; 314:C3-C26. [PMID: 28971835 DOI: 10.1152/ajpcell.00196.2017] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Two prescient 1953 publications set the stage for the elucidation of a novel endocrine system: Schatzmann's report that cardiotonic steroids (CTSs) are all Na+ pump inhibitors, and Szent-Gyorgi's suggestion that there is an endogenous "missing screw" in heart failure that CTSs like digoxin may replace. In 1977 I postulated that an endogenous Na+ pump inhibitor acts as a natriuretic hormone and simultaneously elevates blood pressure (BP) in salt-dependent hypertension. This hypothesis was based on the idea that excess renal salt retention promoted the secretion of a CTS-like hormone that inhibits renal Na+ pumps and salt reabsorption. The hormone also inhibits arterial Na+ pumps, elevates myocyte Na+ and promotes Na/Ca exchanger-mediated Ca2+ gain. This enhances vasoconstriction and arterial tone-the hallmark of hypertension. Here I describe how those ideas led to the discovery that the CTS-like hormone is endogenous ouabain (EO), a key factor in the pathogenesis of hypertension and heart failure. Seminal observations that underlie the still-emerging picture of the EO-Na+ pump endocrine system in the physiology and pathophysiology of multiple organ systems are summarized. Milestones include: 1) cloning the Na+ pump isoforms and physiological studies of mutated pumps in mice; 2) discovery that Na+ pumps are also EO-triggered signaling molecules; 3) demonstration that ouabain, but not digoxin, is hypertensinogenic; 4) elucidation of EO's roles in kidney development and cardiovascular and renal physiology and pathophysiology; 5) discovery of "brain ouabain", a component of a novel hypothalamic neuromodulatory pathway; and 6) finding that EO and its brain receptors modulate behavior and learning.
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Affiliation(s)
- Mordecai P Blaustein
- Departments of Physiology and Medicine, University of Maryland School of Medicine , Baltimore, Maryland
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Blaustein MP. How does pressure overload cause cardiac hypertrophy and dysfunction? High-ouabain affinity cardiac Na + pumps are crucial. Am J Physiol Heart Circ Physiol 2017; 313:H919-H930. [PMID: 28733446 PMCID: PMC5792198 DOI: 10.1152/ajpheart.00131.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 07/18/2017] [Accepted: 07/18/2017] [Indexed: 12/17/2022]
Abstract
Left ventricular hypertrophy is frequently observed in hypertensive patients and is believed to be due to the pressure overload and cardiomyocyte stretch. Three recent reports on mice with genetically engineered Na+ pumps, however, have demonstrated that cardiac ouabain-sensitive α2-Na+ pumps play a key role in the pathogenesis of transaortic constriction-induced hypertrophy. Hypertrophy was delayed/attenuated in mice with mutant, ouabain-resistant α2-Na+ pumps and in mice with cardiac-selective knockout or transgenic overexpression of α2-Na+ pumps. The latter, seemingly paradoxical, findings can be explained by comparing the numbers of available (ouabain-free) high-affinity (α2) ouabain-binding sites in wild-type, knockout, and transgenic hearts. Conversely, hypertrophy was accelerated in α2-ouabain-resistant (R) mice in which the normally ouabain-resistant α1-Na+ pumps were mutated to an ouabain-sensitive (S) form (α1S/Sα2R/R or "SWAP" vs. wild-type or α1R/R α2S/S mice). Furthermore, transaortic constriction-induced hypertrophy in SWAP mice was prevented/reversed by immunoneutralizing circulating endogenous ouabain (EO). These findings show that EO and its receptor, ouabain-sensitive α2, are critical factors in pressure overload-induced cardiac hypertrophy. This complements reports linking elevated plasma EO to hypertension, cardiac hypertrophy, and failure in humans and elucidates the underappreciated role of the EO-Na+ pump pathway in cardiovascular disease.
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Affiliation(s)
- Mordecai P. Blaustein
- Departments of Physiology and Medicine, University of Maryland School of Medicine, Baltimore, Maryland
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Leenen FHH, Blaustein MP, Hamlyn JM. Update on angiotensin II: new endocrine connections between the brain, adrenal glands and the cardiovascular system. Endocr Connect 2017; 6:R131-R145. [PMID: 28855243 PMCID: PMC5613704 DOI: 10.1530/ec-17-0161] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 08/30/2017] [Indexed: 12/11/2022]
Abstract
In the brain, angiotensinergic pathways play a major role in chronic regulation of cardiovascular and electrolyte homeostasis. Increases in plasma angiotensin II (Ang II), aldosterone, [Na+] and cytokines can directly activate these pathways. Chronically, these stimuli also activate a slow neuromodulatory pathway involving local aldosterone, mineralocorticoid receptors (MRs), epithelial sodium channels and endogenous ouabain (EO). This pathway increases AT1R and NADPH oxidase subunits and maintains/further increases the activity of angiotensinergic pathways. These brain pathways not only increase the setpoint of sympathetic activity per se, but also enhance its effectiveness by increasing plasma EO and EO-dependent reprogramming of arterial and cardiac function. Blockade of any step in this slow pathway or of AT1R prevents Ang II-, aldosterone- or salt and renal injury-induced forms of hypertension. MR/AT1R activation in the CNS also contributes to the activation of sympathetic activity, the circulatory and cardiac RAAS and increase in circulating cytokines in HF post MI. Chronic central infusion of an aldosterone synthase inhibitor, MR blocker or AT1R blocker prevents a major part of the structural remodeling of the heart and the decrease in LV function post MI, indicating that MR activation in the CNS post MI depends on aldosterone, locally produced in the CNS. Thus, Ang II, aldosterone and EO are not simply circulating hormones that act on the CNS but rather they are also paracrine neurohormones, locally produced in the CNS, that exert powerful effects in key CNS pathways involved in the long-term control of sympathetic and neuro-endocrine function and cardiovascular homeostasis.
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Affiliation(s)
- Frans H H Leenen
- Brain and Heart Research GroupUniversity of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Mordecai P Blaustein
- Department of PhysiologyUniversity of Maryland School of Medicine, Baltimore, Maryland, USA
- Department of MedicineUniversity of Maryland School of Medicine, Baltimore, Maryland, USA
| | - John M Hamlyn
- Department of PhysiologyUniversity of Maryland School of Medicine, Baltimore, Maryland, USA
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Subcellular localization of Na/K-ATPase isoforms in ventricular myocytes. J Mol Cell Cardiol 2017; 108:158-169. [PMID: 28587810 DOI: 10.1016/j.yjmcc.2017.05.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Revised: 05/29/2017] [Accepted: 05/31/2017] [Indexed: 11/22/2022]
Abstract
The sodium/potassium ATPase (NKA) is essential for establishing the normal intracellular [Na+] and [K+] and transmembrane gradients that are essential for many cellular functions, including cardiac electrophysiology and contractility. Different NKA isoforms exhibit differential expression levels, cellular localization, and function in different tissues and species. Prior work has indicated that the NKA-α1 isoform is quantitatively predominant in cardiac myocytes, but that the α2 isoform is preferentially concentrated in the transverse tubules (TT), possibly at junctions with the sarcoplasmic reticulum (SR) where α2 may preferentially modulate cardiac contractility. Here we measured subcellular localization of NKA-α1 and α2 using super-resolution microscopy (STED and STORM) and isoform-selective antibodies in mouse ventricular myocytes. We confirm the preferential localization of NKA-α2 in TT vs. surface sarcolemma, but also show that α2 is relatively excluded from longitudinal TT elements. In contrast NKA-α1 is relatively uniformly expressed in all three sarcolemmal regions. We also tested the hypothesis that NKA-α2 (vs. α1) is preferentially concentrated at SR junctional sites near ryanodine receptors (RyR2). The results refute this hypothesis, in that NKA-α1 and α2 were equally close to RyR2 at the TT, with no preferential NKA isoform localization near RyR2. We conclude that in contrast to relatively uniform NKA-α1 distribution, NKA-α2 is preferentially concentrated in the truly transverse (and not longitudinal) TT elements. However, NKA-α2 does not preferentially cluster at RyR2 junctions, so the TT NKA-α2 concentration may suffice for preferential effects of NKA-α2 inhibition on cardiac contractility.
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Kurtz TW, DiCarlo SE, Pravenec M, Morris RC. An Appraisal of Methods Recently Recommended for Testing Salt Sensitivity of Blood Pressure. J Am Heart Assoc 2017; 6:JAHA.117.005653. [PMID: 28365569 PMCID: PMC5533040 DOI: 10.1161/jaha.117.005653] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Theodore W Kurtz
- Department of Laboratory Medicine, University of California, San Francisco, San Francisco, CA
| | | | - Michal Pravenec
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - R Curtis Morris
- Department of Medicine, University of California, San Francisco, San Francisco, CA
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50
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Affiliation(s)
- John M Hamlyn
- From the Departments of Physiology (J.M.H., M.P.B.) and Medicine (M.P.B.), University of Maryland School of Medicine, Baltimore.
| | - Mordecai P Blaustein
- From the Departments of Physiology (J.M.H., M.P.B.) and Medicine (M.P.B.), University of Maryland School of Medicine, Baltimore.
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