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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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Renaud JM, Ørtenblad N, McKenna MJ, Overgaard K. Exercise and fatigue: integrating the role of K +, Na + and Cl - in the regulation of sarcolemmal excitability of skeletal muscle. Eur J Appl Physiol 2023; 123:2345-2378. [PMID: 37584745 PMCID: PMC10615939 DOI: 10.1007/s00421-023-05270-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 06/29/2023] [Indexed: 08/17/2023]
Abstract
Perturbations in K+ have long been considered a key factor in skeletal muscle fatigue. However, the exercise-induced changes in K+ intra-to-extracellular gradient is by itself insufficiently large to be a major cause for the force decrease during fatigue unless combined to other ion gradient changes such as for Na+. Whilst several studies described K+-induced force depression at high extracellular [K+] ([K+]e), others reported that small increases in [K+]e induced potentiation during submaximal activation frequencies, a finding that has mostly been ignored. There is evidence for decreased Cl- ClC-1 channel activity at muscle activity onset, which may limit K+-induced force depression, and large increases in ClC-1 channel activity during metabolic stress that may enhance K+ induced force depression. The ATP-sensitive K+ channel (KATP channel) is also activated during metabolic stress to lower sarcolemmal excitability. Taking into account all these findings, we propose a revised concept in which K+ has two physiological roles: (1) K+-induced potentiation and (2) K+-induced force depression. During low-moderate intensity muscle contractions, the K+-induced force depression associated with increased [K+]e is prevented by concomitant decreased ClC-1 channel activity, allowing K+-induced potentiation of sub-maximal tetanic contractions to dominate, thereby optimizing muscle performance. When ATP demand exceeds supply, creating metabolic stress, both KATP and ClC-1 channels are activated. KATP channels contribute to force reductions by lowering sarcolemmal generation of action potentials, whilst ClC-1 channel enhances the force-depressing effects of K+, thereby triggering fatigue. The ultimate function of these changes is to preserve the remaining ATP to prevent damaging ATP depletion.
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Affiliation(s)
- Jean-Marc Renaud
- Faculty of Medicine, Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Rd., Ottawa, ON, K1H 8M5, Canada.
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Michael J McKenna
- Institute for Health and Sport, Victoria University, Melbourne, VIC, 8001, Australia
- College of Physical Education, Southwest University, Chongqing, China
- College of Sport Science, Zhuhai College of Science and Technology, Zhuhai, China
| | - Kristian Overgaard
- Exercise Biology, Department of Public Health, Aarhus University, Aarhus, Denmark
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3
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Medina-Ortiz K, Navia F, Mosquera-Gil C, Sánchez A, Sterling G, Fierro L, Castaño S. Identification of the NA +/K +-ATPase α-Isoforms in Six Species of Poison Dart Frogs and their Sensitivity to Cardiotonic Steroids. J Chem Ecol 2023; 49:116-132. [PMID: 36877397 PMCID: PMC10102066 DOI: 10.1007/s10886-023-01404-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 03/07/2023]
Abstract
Cardiotonic steroids (CTS) are a group of compounds known to be toxic due to their ability to inhibit the Na+/K+-ATPase (NKA), which is essential to maintain the balance of ions in animal cells. An evolutionary strategy of molecular adaptation to avoid self-intoxication acquired by CTS defended organisms and their predators is the structural modification of their NKA where specific amino acid substitutions confer resistant phenotypes. Several lineages of poison dart frogs (Dendrobatidae) are well known to sequester a wide variety of lipophilic alkaloids from their arthropod diet, however there is no evidence of CTS-sequestration or dietary exposure. Interestingly this study identified the presence of α-NKA isoforms (α1 and α2) with amino acid substitutions indicative of CTS-resistant phenotypes in skeletal muscle transcriptomes obtained from six species of dendrobatids: Phyllobates aurotaenia, Oophaga anchicayensis, Epipedobates boulengeri, Andinobates bombetes, Andinobates minutus, and Leucostethus brachistriatus, collected in the Valle del Cauca (Colombia). P. aurotaenia, A. minutus, and E. boulengeri presented two variants for α1-NKA, with one of them having these substitutions. In contrast, O. anchicayensis and A. bombetes have only one α1-NKA isoform with an amino acid sequence indicative of CTS susceptibility and an α2-NKA with one substitution that could confer a reduced affinity for CTS. The α1 and α2 isoforms of L. brachistriatus do not contain substitutions imparting CTS resistance. Our findings indicate that poison dart frogs express α-NKA isoforms with different affinities for CTS and the pattern of this expression might be influenced by factors related to evolutionary, physiological, ecological, and geographical burdens.
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Affiliation(s)
- Katherine Medina-Ortiz
- Laboratorio de Herpetología Y Toxinología, Department of Physiological Sciences, Faculty of Health, Universidad del Valle, Cali, Colombia.
| | - Felipe Navia
- Laboratorio de Herpetología Y Toxinología, Department of Physiological Sciences, Faculty of Health, Universidad del Valle, Cali, Colombia
| | - Claudia Mosquera-Gil
- Laboratorio de Herpetología Y Toxinología, Department of Physiological Sciences, Faculty of Health, Universidad del Valle, Cali, Colombia
| | - Adalberto Sánchez
- Laboratorio de Herpetología Y Toxinología, Department of Physiological Sciences, Faculty of Health, Universidad del Valle, Cali, Colombia
| | - Gonzalo Sterling
- Laboratorio de Herpetología Y Toxinología, Department of Physiological Sciences, Faculty of Health, Universidad del Valle, Cali, Colombia
| | - Leonardo Fierro
- Laboratorio de Herpetología Y Toxinología, Department of Physiological Sciences, Faculty of Health, Universidad del Valle, Cali, Colombia
| | - Santiago Castaño
- Laboratorio de Herpetología Y Toxinología, Department of Physiological Sciences, Faculty of Health, Universidad del Valle, Cali, Colombia.
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4
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Ni X, Yin X, Qi C, Liu C, Chen H, Zhou Y, Ao W, Bao S, Xue J, Yang J, Dong W. Cardiotoxicity of (-)-borneol, (+)-borneol, and isoborneol in zebrafish embryos is associated with Na + /K + -ATPase and Ca 2+ -ATPase inhibition. J Appl Toxicol 2023; 43:373-386. [PMID: 36062847 DOI: 10.1002/jat.4388] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 08/08/2022] [Accepted: 08/30/2022] [Indexed: 11/10/2022]
Abstract
Borneol is an example of traditional Chinese medicine widely used in Asia. There are different isomers of chiral borneol in the market, but its toxicity and effects need further study. In this study, we used zebrafish embryos to examine the effects of exposure to three isomers of borneol [(-)-borneol, (+)-borneol, and isoborneol] on heart development and the association with Na+ /K+ -ATPase from 4 h post-fertilization (4 hpf). The results showed that the three isomers of borneol increased mortality and decreased hatching rate when the zebrafish embryo developed to 72 hpf. All three isomers of borneol (0.01-1.0 mM) significantly reduced heart rate from 48 to 120 hpf and reduced the expression of genes related to Ca2+ -ATPase (cacna1ab and cacna1da) and Na+ /K+ -ATPase (atp1b2b, atp1a3b, and atp1a2). At the same time, the three isomers of borneol significantly reduced the activities of Ca2+ -ATPase and Na+ /K+ -ATPase at 0.1 to 1.0 mM. (+)-Borneol caused the most significant reduction (p < 0.05), followed by isoborneol and (-)-borneol. Na+ /K+ -ATPase was mainly expressed in otic vesicles and protonephridium. All three isomers of borneol reduced Na+ /K+ -ATPase mRNA expression, but isoborneol was the most significant (p < 0.01). Our results indicated that (+)-borneol was the least toxic of the three isomers while the isoborneol showed the most substantial toxic effect, closely related to effects on Na+ /K+ -ATPase.
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Affiliation(s)
- Xuan Ni
- Inner Mongolia Key Laboratory of Toxicant Monitoring and Toxicology, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, China.,School of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, China
| | - Xiaoyu Yin
- Inner Mongolia Key Laboratory of Toxicant Monitoring and Toxicology, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, China
| | - Chelimuge Qi
- Inner Mongolia Key Laboratory of Toxicant Monitoring and Toxicology, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, China
| | - Chunyu Liu
- Inner Mongolia Key Laboratory of Toxicant Monitoring and Toxicology, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, China
| | - Hao Chen
- Inner Mongolia Key Laboratory of Toxicant Monitoring and Toxicology, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, China
| | - Yini Zhou
- Inner Mongolia Key Laboratory of Toxicant Monitoring and Toxicology, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, China
| | - Wuliji Ao
- Inner Mongolia Research Institute of Traditional Mongolian Medicine Engineering technology/College of Mongolian Medicine and Pharmacy, Inner Mongolia Minzu University, Tongliao, China
| | - Shuyin Bao
- The Medical College of Inner Mongolia Minzu University, Tongliao, China
| | - Jiangdong Xue
- Inner Mongolia Key Laboratory of Toxicant Monitoring and Toxicology, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, China
| | - Jingfeng Yang
- Inner Mongolia Key Laboratory of Toxicant Monitoring and Toxicology, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, China
| | - Wu Dong
- Inner Mongolia Key Laboratory of Toxicant Monitoring and Toxicology, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, China
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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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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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Parreira GM, Faria JA, Marques SMS, Garcia IJP, Silva IF, De Carvalho LED, Villar JAFP, Machado MV, de Castro Lima M, Barbosa LA, Cortes VF, de Lima Santos H. The γ-Benzylidene Digoxin Derivative BD-15 Increases the α3-Na, K-ATPase Activity in Rat Hippocampus and Prefrontal Cortex and no Change on Heart. J Membr Biol 2021; 254:189-199. [PMID: 33598793 DOI: 10.1007/s00232-021-00173-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 01/13/2021] [Indexed: 02/06/2023]
Abstract
Our study aimed to investigate the effects of the new cardiotonic steroid BD-15 (γ-benzylidene derivatives) in the behavioral parameters, oxidative stress and the Na, K-ATPase activity in the hippocampus, prefrontal cortex and heart from rats to verify the safety and possible utilization in brain disorders. For this study, groups of male Wistar rats were used after intraperitoneal injection of 20, 100 and 200 µg/Kg with BD-15. The groups were treated for three consecutive days and the control group received 0.9% saline. BD-15 did not alter behavior of rats treated with different doses. An increase in the specific α2,3-Na, K-ATPase activity was observed for all doses of BD-15 tested in the hippocampus. However, in the prefrontal cortex, only the dose of 100 µg/Kg increased the activity of all Na, K-ATPase isoforms. BD-15 did not cause alteration in the lipid peroxidation levels in the hippocampus, but in the prefrontal cortex, a decrease of lipid peroxidation (~ 25%) was observed. In the hippocampus, GSH levels increased with all doses tested, while in the prefrontal cortex no changes were found. Subsequently, when the effect of BD-15 on cardiac tissue was analyzed, no changes were observed in the tested parameters. BD-15 at a dosage of 100 µg/Kg proved to be promising because it is considered therapeutic for brain disorders, since it increases the activity of the α3-Na, K-ATPase in the hippocampus and prefrontal cortex, as well as decreasing the oxidative stress in these brain regions. In addition, this drug did not cause changes in the tissues of the heart and kidneys, preferentially demonstrating specificity for the brain.
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Affiliation(s)
- Gabriela Machado Parreira
- Laboratório de Bioquímica Celular, Universidade Federal de São João Del Rei, Campus Centro-Oeste Dona Lindu, Av Sebastião Gonçalves Coelho, 400, Divinopolis, MG, Zip Code: 35501-296, Brazil
| | - Jéssica Alves Faria
- Laboratório de Anatomia Humana, Universidade Federal de São João Del Rei, Campus Centro-Oeste Dona Lindu, Divinopolis, MG, Brazil
| | - Sarah Melo Silva Marques
- Laboratório de Bioquímica Celular, Universidade Federal de São João Del Rei, Campus Centro-Oeste Dona Lindu, Av Sebastião Gonçalves Coelho, 400, Divinopolis, MG, Zip Code: 35501-296, Brazil
| | - Israel José Pereira Garcia
- Laboratório de Bioquímica Celular, Universidade Federal de São João Del Rei, Campus Centro-Oeste Dona Lindu, Av Sebastião Gonçalves Coelho, 400, Divinopolis, MG, Zip Code: 35501-296, Brazil
| | - Isabella Ferreira Silva
- Laboratório de Processamento de Tecidos, Universidade Federal de São João Del Rei, Campus Centro-Oeste Dona Lindu, Divinopolis, MG, Brazil
| | - Luciana Estefani Drumond De Carvalho
- Laboratório de Bioquímica Celular, Universidade Federal de São João Del Rei, Campus Centro-Oeste Dona Lindu, Av Sebastião Gonçalves Coelho, 400, Divinopolis, MG, Zip Code: 35501-296, Brazil
| | - José Augusto Ferreira Perez Villar
- Laboratório de Síntese Orgânica e Nanoestruturas, Universidade Federal de São João Del Rei, Campus Centro-Oeste Dona Lindu, Divinopolis, MG, Brazil
| | - Matthews Vieira Machado
- Laboratório de Síntese Orgânica e Nanoestruturas, Universidade Federal de São João Del Rei, Campus Centro-Oeste Dona Lindu, Divinopolis, MG, Brazil
| | - Maira de Castro Lima
- Laboratório de Anatomia Humana, Universidade Federal de São João Del Rei, Campus Centro-Oeste Dona Lindu, Divinopolis, MG, Brazil
| | - Leandro Augusto Barbosa
- Laboratório de Bioquímica Celular, Universidade Federal de São João Del Rei, Campus Centro-Oeste Dona Lindu, Av Sebastião Gonçalves Coelho, 400, Divinopolis, MG, Zip Code: 35501-296, Brazil
| | - Vanessa Faria Cortes
- Laboratório de Bioquímica Celular, Universidade Federal de São João Del Rei, Campus Centro-Oeste Dona Lindu, Av Sebastião Gonçalves Coelho, 400, Divinopolis, MG, Zip Code: 35501-296, Brazil
| | - Hérica de Lima Santos
- Laboratório de Bioquímica Celular, Universidade Federal de São João Del Rei, Campus Centro-Oeste Dona Lindu, Av Sebastião Gonçalves Coelho, 400, Divinopolis, MG, Zip Code: 35501-296, Brazil.
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8
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Lindinger MI, Cairns SP. Regulation of muscle potassium: exercise performance, fatigue and health implications. Eur J Appl Physiol 2021; 121:721-748. [PMID: 33392745 DOI: 10.1007/s00421-020-04546-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 10/29/2020] [Indexed: 12/30/2022]
Abstract
This review integrates from the single muscle fibre to exercising human the current understanding of the role of skeletal muscle for whole-body potassium (K+) regulation, and specifically the regulation of skeletal muscle [K+]. We describe the K+ transport proteins in skeletal muscle and how they contribute to, or modulate, K+ disturbances during exercise. Muscle and plasma K+ balance are markedly altered during and after high-intensity dynamic exercise (including sports), static contractions and ischaemia, which have implications for skeletal and cardiac muscle contractile performance. Moderate elevations of plasma and interstitial [K+] during exercise have beneficial effects on multiple physiological systems. Severe reductions of the trans-sarcolemmal K+ gradient likely contributes to muscle and whole-body fatigue, i.e. impaired exercise performance. Chronic or acute changes of arterial plasma [K+] (hyperkalaemia or hypokalaemia) have dangerous health implications for cardiac function. The current mechanisms to explain how raised extracellular [K+] impairs cardiac and skeletal muscle function are discussed, along with the latest cell physiology research explaining how calcium, β-adrenergic agonists, insulin or glucose act as clinical treatments for hyperkalaemia to protect the heart and skeletal muscle in vivo. Finally, whether these agents can also modulate K+-induced muscle fatigue are evaluated.
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Affiliation(s)
- Michael I Lindinger
- Research and Development, The Nutraceutical Alliance, Burlington, ON, L7N 2Z9, Canada
| | - Simeon P Cairns
- SPRINZ, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, 1020, New Zealand.
- Health and Rehabilitation Research Institute, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, 1020, New Zealand.
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9
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Alharbi Y, Kapur A, Felder M, Barroilhet L, Pattnaik BR, Patankar MS. Oxidative stress induced by the anti-cancer agents, plumbagin, and atovaquone, inhibits ion transport through Na +/K +-ATPase. Sci Rep 2020; 10:19585. [PMID: 33177587 PMCID: PMC7659016 DOI: 10.1038/s41598-020-76342-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 10/05/2020] [Indexed: 11/23/2022] Open
Abstract
Oxidative stress inhibits Na+/K+-ATPase (NKA), the ion channel that maintains membrane potential. Here, we investigate the role of oxidative stress-mediated by plumbagin and atovaquone in the inhibition of NKA activity. We confirm that plumbagin and atovaquone inhibit the proliferation of three human (OVCAR-3, SKOV-3, and TYKNu) and one mouse (ID8) ovarian cancer cell lines. The oxygen radical scavenger, N-acetylcysteine (NAC), attenuates the chemotoxicity of plumbagin and atovaquone. Whole-cell patch clamping demonstrates that plumbagin and atovaquone inhibit outward and the inward current flowing through NKA in SKOV-3 and OVCAR-3. Although both drugs decrease cellular ATP; providing exogenous ATP (5 mM) in the pipet solution used during patch clamping did not recover NKA activity in the plumbagin or atovaquone treated SKOV-3 and OVCAR-3 cells. However, pretreatment of the cells with NAC completely abrogated the NKA inhibitory activity of plumbagin and atovaquone. Exposure of the SKOV-3 cells to either drug significantly decreases the expression of NKA. We conclude that oxidative stress caused by plumbagin and atovaquone degrades NKA, resulting in the inability to maintain ion transport. Therefore, when evaluating compounds that induce oxidative stress, it is important to consider the contribution of NKA inhibition to their cytotoxic effects on tumor cells.
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Affiliation(s)
- Yousef Alharbi
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI, 53792, USA.,Department of Veterinary Medicine, Qassim University, Qassim, Saudi Arabia
| | - Arvinder Kapur
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI, 53792, USA
| | - Mildred Felder
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI, 53792, USA
| | - Lisa Barroilhet
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI, 53792, USA
| | - Bikash R Pattnaik
- Department of Pediatrics, Ophthalmology and Visual Sciences, McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, 53706, USA.
| | - Manish S Patankar
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI, 53792, USA.
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10
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Pirkmajer S, Bezjak K, Matkovič U, Dolinar K, Jiang LQ, Miš K, Gros K, Milovanova K, Pirkmajer KP, Marš T, Kapilevich L, Chibalin AV. Ouabain Suppresses IL-6/STAT3 Signaling and Promotes Cytokine Secretion in Cultured Skeletal Muscle Cells. Front Physiol 2020; 11:566584. [PMID: 33101052 PMCID: PMC7544989 DOI: 10.3389/fphys.2020.566584] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 08/25/2020] [Indexed: 12/16/2022] Open
Abstract
The cardiotonic steroids (CTS), such as ouabain and marinobufagenin, are thought to be adrenocortical hormones secreted during exercise and the stress response. The catalytic α-subunit of Na,K-ATPase (NKA) is a CTS receptor, whose largest pool is located in skeletal muscles, indicating that muscles are a major target for CTS. Skeletal muscles contribute to adaptations to exercise by secreting interleukin-6 (IL-6) and plethora of other cytokines, which exert paracrine and endocrine effects in muscles and non-muscle tissues. Here, we determined whether ouabain, a prototypical CTS, modulates IL-6 signaling and secretion in the cultured human skeletal muscle cells. Ouabain (2.5–50 nM) suppressed the abundance of STAT3, a key transcription factor downstream of the IL-6 receptor, as well as its basal and IL-6-stimulated phosphorylation. Conversely, ouabain (50 nM) increased the phosphorylation of ERK1/2, Akt, p70S6K, and S6 ribosomal protein, indicating activation of the ERK1/2 and the Akt-mTOR pathways. Proteasome inhibitor MG-132 blocked the ouabain-induced suppression of the total STAT3, but did not prevent the dephosphorylation of STAT3. Ouabain (50 nM) suppressed hypoxia-inducible factor-1α (HIF-1α), a modulator of STAT3 signaling, but gene silencing of HIF-1α and/or its partner protein HIF-1β did not mimic effects of ouabain on the phosphorylation of STAT3. Ouabain (50 nM) failed to suppress the phosphorylation of STAT3 and HIF-1α in rat L6 skeletal muscle cells, which express the ouabain-resistant α1-subunit of NKA. We also found that ouabain (100 nM) promoted the secretion of IL-6, IL-8, GM-CSF, and TNF-α from the skeletal muscle cells of healthy subjects, and the secretion of GM-CSF from cells of subjects with the type 2 diabetes. Marinobufagenin (10 nM), another important CTS, did not alter the secretion of these cytokines. In conclusion, our study shows that ouabain suppresses the IL-6 signaling via STAT3, but promotes the secretion of IL-6 and other cytokines, which might represent a negative feedback in the IL-6/STAT3 pathway. Collectively, our results implicate a role for CTS and NKA in regulation of the IL-6 signaling and secretion in skeletal muscle.
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Affiliation(s)
- Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Katja Bezjak
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Urška Matkovič
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Klemen Dolinar
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Lake Q Jiang
- Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Katarina Gros
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Kseniya Milovanova
- Department of Sports and Health Tourism, Sports Physiology and Medicine, National Research Tomsk State University, Tomsk, Russia
| | - Katja Perdan Pirkmajer
- Department of Rheumatology, University Medical Centre Ljubljana, Ljubljana, Slovenia.,Department of Internal Medicine, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Tomaž Marš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Leonid Kapilevich
- Department of Sports and Health Tourism, Sports Physiology and Medicine, National Research Tomsk State University, Tomsk, Russia.,Central Scientific Laboratory, Siberian State Medical University, Tomsk, Russia
| | - Alexander V Chibalin
- Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
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11
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Lopina OD, Tverskoi AM, Klimanova EA, Sidorenko SV, Orlov SN. Ouabain-Induced Cell Death and Survival. Role of α1-Na,K-ATPase-Mediated Signaling and [Na +] i/[K +] i-Dependent Gene Expression. Front Physiol 2020; 11:1060. [PMID: 33013454 PMCID: PMC7498651 DOI: 10.3389/fphys.2020.01060] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 07/31/2020] [Indexed: 12/12/2022] Open
Abstract
Ouabain is of cardiotonic steroids (CTS) family that is plant-derived compounds and is known for many years as therapeutic and cytotoxic agents. They are specific inhibitors of Na,K-ATPase, the enzyme, which pumps Na+ and K+ across plasma membrane of animal cells. Treatment of cells by CTS affects various cellular functions connected with the maintenance of the transmembrane gradient of Na+ and K+. Numerous studies demonstrated that binding of CTS to Na,K-ATPase not only suppresses its activity but also induces some signal pathways. This review is focused on different mechanisms of two ouabain effects: their ability (1) to protect rodent cells from apoptosis through the expression of [Na+]i-sensitive genes and (2) to trigger death of non-rodents cells (so-called «oncosis»), possessing combined markers of «classic» necrosis and «classic» apoptosis. Detailed study of oncosis demonstrated that the elevation of the [Na+]i/[K+]i ratio is not a sufficient for its triggering. Non-rodent cell death is determined by the characteristic property of "sensitive" to ouabain α1-subunit of Na,K-ATPase. In this case, ouabain binding leads to enzyme conformational changes triggering the activation of p38 mitogen-activated protein kinases (MAPK) signaling. The survival of rodent cells with ouabain-«resistant» α1-subunit is connected with another conformational transition induced by ouabain binding that results in the activation of ERK 1/2 signaling pathway.
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Affiliation(s)
- Olga Dmitrievna Lopina
- Department of Biochemistry, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Artem Mikhaylovich Tverskoi
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences (RAS), Moscow, Russia
- Laboratory of Biological Membranes, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | | | | | - Sergei Nikolaevich Orlov
- Laboratory of Biological Membranes, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
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12
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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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13
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Kravtsova VV, Bouzinova EV, Chibalin AV, Matchkov VV, Krivoi II. Isoform-specific Na,K-ATPase and membrane cholesterol remodeling in motor endplates in distinct mouse models of myodystrophy. Am J Physiol Cell Physiol 2020; 318:C1030-C1041. [PMID: 32293933 DOI: 10.1152/ajpcell.00453.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Na,K-ATPase is a membrane transporter that is critically important for skeletal muscle function. Mdx and Bla/J mice are the experimental models of Duchenne muscular dystrophy and dysferlinopathy that are known to differ in the molecular mechanism of the pathology. This study examines the function of α1- and α2-Na,K-ATPase isozymes in respiratory diaphragm and postural soleus muscles from mdx and Bla/J mice compared with control С57Bl/6 mice. In diaphragm muscles, the motor endplate structure was severely disturbed (manifested by defragmentation) in mdx mice only. The endplate membrane of both Bla/J and mdx mice was depolarized due to specific loss of the α2-Na,K-ATPase electrogenic activity and its decreased membrane abundance. Total FXYD1 subunit (modulates Na,K-ATPase activity) abundance was decreased in both mouse models. However, the α2-Na,K-ATPase protein content as well as mRNA expression were specifically and significantly reduced only in mdx mice. The endplate membrane cholesterol redistribution was most pronounced in mdx mice. Soleus muscles from Bla/J and mdx mice demonstrated reduction of the α2-Na,K-ATPase membrane abundance and mRNA expression similar to the diaphragm muscles. In contrast to diaphragm, the α2-Na,K-ATPase protein content was altered in both Bla/J and mdx mice; membrane cholesterol re-distribution was not observed. Thus, the α2-Na,K-ATPase is altered in both Bla/J and mdx mouse models of chronic muscle pathology. However, despite some similarities, the α2-Na,K-ATPase and cholesterol abnormalities are more pronounced in mdx mice.
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Affiliation(s)
- 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
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14
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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: 45] [Impact Index Per Article: 11.3] [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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15
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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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16
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Kutz LC, Mukherji ST, Wang X, Bryant A, Larre I, Heiny JA, Lingrel JB, Pierre SV, Xie Z. Isoform-specific role of Na/K-ATPase α1 in skeletal muscle. Am J Physiol Endocrinol Metab 2018; 314:E620-E629. [PMID: 29438630 PMCID: PMC6032065 DOI: 10.1152/ajpendo.00275.2017] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The distribution of Na/K-ATPase α-isoforms in skeletal muscle is unique, with α1 as the minor (15%) isoform and α2 comprising the bulk of the Na/K-ATPase pool. The acute and isoform-specific role of α2 in muscle performance and resistance to fatigue is well known, but the isoform-specific role of α1 has not been as thoroughly investigated. In vitro, we reported that α1 has a role in promoting cell growth that is not supported by α2. To assess whether α1 serves this isoform-specific trophic role in the skeletal muscle, we used Na/K-ATPase α1-haploinsufficient (α1+/-) mice. A 30% decrease of Na/K-ATPase α1 protein expression without change in α2 induced a modest yet significant decrease of 10% weight in the oxidative soleus muscle. In contrast, the mixed plantaris and glycolytic extensor digitorum longus weights were not significantly affected, likely because of their very low expression level of α1 compared with the soleus. The soleus mass reduction occurred without change in total Na/K-ATPase activity or glycogen metabolism. Serum analytes including K+, fat tissue mass, and exercise capacity were not altered in α1+/- mice. The impact of α1 content on soleus muscle mass is consistent with a Na/K-ATPase α1-specific role in skeletal muscle growth that cannot be fulfilled by α2. The preserved running capacity in α1+/- is in sharp contrast with previously reported consequences of genetic manipulation of α2. Taken together, these results lend further support to the concept of distinct isoform-specific functions of Na/K-ATPase α1 and α2 in skeletal muscle.
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Affiliation(s)
- Laura C Kutz
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, West Virginia
| | - Shreya T Mukherji
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, West Virginia
| | - Xiaoliang Wang
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, West Virginia
| | - Amber Bryant
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, West Virginia
| | - Isabel Larre
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, West Virginia
| | - Judith A Heiny
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine , Cincinnati, Ohio
| | - Jerry B Lingrel
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine , Cincinnati, Ohio
| | - Sandrine V Pierre
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, West Virginia
| | - Zijian Xie
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, West Virginia
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17
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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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18
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Danilov K, Sidorenko S, Milovanova K, Klimanova E, Kapilevich LV, Orlov SN. Electrical pulse stimulation decreases electrochemical Na + and K + gradients in C2C12 myotubes. Biochem Biophys Res Commun 2017; 493:875-878. [DOI: 10.1016/j.bbrc.2017.09.133] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 09/23/2017] [Indexed: 11/27/2022]
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19
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20
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Blaustein MP, Chen L, Hamlyn JM, Leenen FHH, Lingrel JB, Wier WG, Zhang J. Pivotal role of α2 Na + pumps and their high affinity ouabain binding site in cardiovascular health and disease. J Physiol 2016; 594:6079-6103. [PMID: 27350568 DOI: 10.1113/jp272419] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 06/18/2016] [Indexed: 12/13/2022] Open
Abstract
Reduced smooth muscle (SM)-specific α2 Na+ pump expression elevates basal blood pressure (BP) and increases BP sensitivity to angiotensin II (Ang II) and dietary NaCl, whilst SM-α2 overexpression lowers basal BP and decreases Ang II/salt sensitivity. Prolonged ouabain infusion induces hypertension in rodents, and ouabain-resistant mutation of the α2 ouabain binding site (α2R/R mice) confers resistance to several forms of hypertension. Pressure overload-induced heart hypertrophy and failure are attenuated in cardio-specific α2 knockout, cardio-specific α2 overexpression and α2R/R mice. We propose a unifying hypothesis that reconciles these apparently disparate findings: brain mechanisms, activated by Ang II and high NaCl, regulate sympathetic drive and a novel neurohumoral pathway mediated by both brain and circulating endogenous ouabain (EO). Circulating EO modulates ouabain-sensitive α2 Na+ pump activity and Ca2+ transporter expression and, via Na+ /Ca2+ exchange, Ca2+ homeostasis. This regulates sensitivity to sympathetic activity, Ca2+ signalling and arterial and cardiac contraction.
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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.
| | - Ling Chen
- 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
| | - Frans H H Leenen
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, ON, Canada, K1Y 4W7
| | - Jerry B Lingrel
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, 45267-0524, USA
| | - W Gil Wier
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Jin Zhang
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
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21
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Pirkmajer S, Chibalin AV. Na,K-ATPase regulation in skeletal muscle. Am J Physiol Endocrinol Metab 2016; 311:E1-E31. [PMID: 27166285 DOI: 10.1152/ajpendo.00539.2015] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 05/02/2016] [Indexed: 12/17/2022]
Abstract
Skeletal muscle contains one of the largest and the most dynamic pools of Na,K-ATPase (NKA) in the body. Under resting conditions, NKA in skeletal muscle operates at only a fraction of maximal pumping capacity, but it can be markedly activated when demands for ion transport increase, such as during exercise or following food intake. Given the size, capacity, and dynamic range of the NKA pool in skeletal muscle, its tight regulation is essential to maintain whole body homeostasis as well as muscle function. To reconcile functional needs of systemic homeostasis with those of skeletal muscle, NKA is regulated in a coordinated manner by extrinsic stimuli, such as hormones and nerve-derived factors, as well as by local stimuli arising in skeletal muscle fibers, such as contractions and muscle energy status. These stimuli regulate NKA acutely by controlling its enzymatic activity and/or its distribution between the plasma membrane and the intracellular storage compartment. They also regulate NKA chronically by controlling NKA gene expression, thus determining total NKA content in skeletal muscle and its maximal pumping capacity. This review focuses on molecular mechanisms that underlie regulation of NKA in skeletal muscle by major extrinsic and local stimuli. Special emphasis is given to stimuli and mechanisms linking regulation of NKA and energy metabolism in skeletal muscle, such as insulin and the energy-sensing AMP-activated protein kinase. Finally, the recently uncovered roles for glutathionylation, nitric oxide, and extracellular K(+) in the regulation of NKA in skeletal muscle are highlighted.
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Affiliation(s)
- Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia; and
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
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22
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Matchkov VV, Krivoi II. Specialized Functional Diversity and Interactions of the Na,K-ATPase. Front Physiol 2016; 7:179. [PMID: 27252653 PMCID: PMC4879863 DOI: 10.3389/fphys.2016.00179] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/04/2016] [Indexed: 12/22/2022] Open
Abstract
Na,K-ATPase is a protein ubiquitously expressed in the plasma membrane of all animal cells and vitally essential for their functions. A specialized functional diversity of the Na,K-ATPase isozymes is provided by molecular heterogeneity, distinct subcellular localizations, and functional interactions with molecular environment. Studies over the last decades clearly demonstrated complex and isoform-specific reciprocal functional interactions between the Na,K-ATPase and neighboring proteins and lipids. These interactions are enabled by a spatially restricted ion homeostasis, direct protein-protein/lipid interactions, and protein kinase signaling pathways. In addition to its "classical" function in ion translocation, the Na,K-ATPase is now considered as one of the most important signaling molecules in neuronal, epithelial, skeletal, cardiac and vascular tissues. Accordingly, the Na,K-ATPase forms specialized sub-cellular multimolecular microdomains which act as receptors to circulating endogenous cardiotonic steroids (CTS) triggering a number of signaling pathways. Changes in these endogenous cardiotonic steroid levels and initiated signaling responses have significant adaptive values for tissues and whole organisms under numerous physiological and pathophysiological conditions. This review discusses recent progress in the studies of functional interactions between the Na,K-ATPase and molecular microenvironment, the Na,K-ATPase-dependent signaling pathways and their significance for diversity of cell function.
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Affiliation(s)
| | - Igor I Krivoi
- Department of General Physiology, St. Petersburg State University St. Petersburg, Russia
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23
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Critical role of the α1-Na(+), K(+)-ATPase subunit in insensitivity of rodent cells to cytotoxic action of ouabain. Apoptosis 2016; 20:1200-10. [PMID: 26067145 DOI: 10.1007/s10495-015-1144-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In rodents, ubiquitous α1-Na(+), K(+)-ATPase is inhibited by ouabain and other cardiotonic steroids (CTS) at ~10(3)-fold higher concentrations than those effective in other mammals. To examine the specific roles of the CTS-sensitive α1S- and CTS-resistant α1R-Na(+), K(+)-ATPase isoforms, we compared the effects of ouabain on intracellular Na(+) and K(+) content, cell survival, and mitogen-activated protein kinases (MAPK) in human and rat vascular smooth muscle cells (HASMC and RASMC), human and rat endothelial cells (HUVEC and RAEC), and human and rat brain astrocytes. 6-h exposure of HASMC and HUVEC to 3 μM ouabain dramatically increased the intracellular [Na(+)]/[K(+)] ratio to the same extend as in RASMC and RAEC treated with 3000 μM ouabain. In 24, 3 μM ouabain triggered the death of all types of human cells used in this study. Unlike human cells, we did not detect any effect of 3000-5000 μM ouabain on the survival of rat cells, or smooth muscle cells from mouse aorta (MASMC). Unlike in the wild-type α1(R/R) mouse, ouabain triggered death of MASMC from α1(S/S) mouse expressing human α1-Na(+), K(+)-ATPase. Furthermore, transfection of HUVEC with rat α1R-Na(+), K(+)-ATPase protected them from the ouabain-induced death. In HUVEC, ouabain led to phosphorylation of p38 MAPK, whereas in RAEC it stimulated phosphorylation of ERK1/2. Overall, our results, demonstrate that the drastic differences in cytotoxic action of ouabain on human and rodent cells are caused by unique features of α1S/α1R-Na(+), K(+)-ATPase, rather than by any downstream CTS-sensitive/resistant components of the cell death machinery.
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24
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Figueroa JAL, Stiner CA, Radzyukevich TL, Heiny JA. Metal ion transport quantified by ICP-MS in intact cells. Sci Rep 2016; 6:20551. [PMID: 26838181 PMCID: PMC4738345 DOI: 10.1038/srep20551] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 01/06/2016] [Indexed: 01/26/2023] Open
Abstract
The use of ICP-MS to measure metal ion content in biological tissues offers a highly sensitive means to study metal-dependent physiological processes. Here we describe the application of ICP-MS to measure membrane transport of Rb and K ions by the Na,K-ATPase in mouse skeletal muscles and human red blood cells. The ICP-MS method provides greater precision and statistical power than possible with conventional tracer flux methods. The method is widely applicable to studies of other metal ion transporters and metal-dependent processes in a range of cell types and conditions.
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Affiliation(s)
- Julio A Landero Figueroa
- Department of Chemistry, University of Cincinnati, Cincinnati, OH USA.,University of Cincinnati/Agilent Technologies Metallomics Center of the Americas, Cincinnati, OH USA
| | - Cory A Stiner
- Department of Chemistry, University of Cincinnati, Cincinnati, OH USA.,University of Cincinnati/Agilent Technologies Metallomics Center of the Americas, Cincinnati, OH USA
| | - Tatiana L Radzyukevich
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, OH USA
| | - Judith A Heiny
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, OH USA
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25
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Kravtsova VV, Petrov AM, Matchkov VV, Bouzinova EV, Vasiliev AN, Benziane B, Zefirov AL, Chibalin AV, Heiny JA, Krivoi II. Distinct α2 Na,K-ATPase membrane pools are differently involved in early skeletal muscle remodeling during disuse. ACTA ACUST UNITED AC 2016; 147:175-88. [PMID: 26755774 PMCID: PMC4727944 DOI: 10.1085/jgp.201511494] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 12/22/2015] [Indexed: 11/29/2022]
Abstract
Location, location, location. The Na-K pump of skeletal muscle is regulated differently at neuromuscular junctions. The Na,K-ATPase is essential for the contractile function of skeletal muscle, which expresses the α1 and α2 subunit isoforms of Na,K-ATPase. The α2 isozyme is predominant in adult skeletal muscles and makes a greater contribution in working compared with noncontracting muscles. Hindlimb suspension (HS) is a widely used model of muscle disuse that leads to progressive atrophy of postural skeletal muscles. This study examines the consequences of acute (6–12 h) HS on the functioning of the Na,K-ATPase α1 and α2 isozymes in rat soleus (disused) and diaphragm (contracting) muscles. Acute disuse dynamically and isoform-specifically regulates the electrogenic activity, protein, and mRNA content of Na,K-ATPase α2 isozyme in rat soleus muscle. Earlier disuse-induced remodeling events also include phospholemman phosphorylation as well as its increased abundance and association with α2 Na,K-ATPase. The loss of α2 Na,K-ATPase activity results in reduced electrogenic pump transport and depolarized resting membrane potential. The decreased α2 Na,K-ATPase activity is caused by a decrease in enzyme activity rather than by altered protein and mRNA content, localization in the sarcolemma, or functional interaction with the nicotinic acetylcholine receptors. The loss of extrajunctional α2 Na,K-ATPase activity depends strongly on muscle use, and even the increased protein and mRNA content as well as enhanced α2 Na,K-ATPase abundance at this membrane region after 12 h of HS cannot counteract this sustained inhibition. In contrast, additional factors may regulate the subset of junctional α2 Na,K-ATPase pool that is able to recover during HS. Notably, acute, low-intensity muscle workload restores functioning of both α2 Na,K-ATPase pools. These results demonstrate that the α2 Na,K-ATPase in rat skeletal muscle is dynamically and acutely regulated by muscle use and provide the first evidence that the junctional and extrajunctional pools of the α2 Na,K-ATPase are regulated differently.
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Affiliation(s)
- Violetta V Kravtsova
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Alexey M Petrov
- Department of Normal Physiology, Kazan State Medical University, Kazan 420012, Russia
| | | | - Elena V Bouzinova
- Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, 8240 Risskov, Denmark
| | - Alexander N Vasiliev
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Boubacar Benziane
- Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Andrey L Zefirov
- Department of Normal Physiology, Kazan State Medical University, Kazan 420012, Russia
| | - Alexander V Chibalin
- Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Judith A Heiny
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267
| | - Igor I Krivoi
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
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Tien VN, Duc LV, Thanh TB. Isolated Compounds and Cardiotonic Effect on the Isolated Rabbit Heart of Methanolic Flower Extract of Nerium oleander L. ACTA ACUST UNITED AC 2016. [DOI: 10.3923/rjphyto.2016.21.29] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Shattock MJ, Ottolia M, Bers DM, Blaustein MP, Boguslavskyi A, Bossuyt J, Bridge JHB, Chen-Izu Y, Clancy CE, Edwards A, Goldhaber J, Kaplan J, Lingrel JB, Pavlovic D, Philipson K, Sipido KR, Xie ZJ. Na+/Ca2+ exchange and Na+/K+-ATPase in the heart. J Physiol 2015; 593:1361-82. [PMID: 25772291 PMCID: PMC4376416 DOI: 10.1113/jphysiol.2014.282319] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 10/30/2014] [Indexed: 12/17/2022] Open
Abstract
This paper is the third in a series of reviews published in this issue resulting from the University of California Davis Cardiovascular Symposium 2014: Systems approach to understanding cardiac excitation–contraction coupling and arrhythmias: Na+ channel and Na+ transport. The goal of the symposium was to bring together experts in the field to discuss points of consensus and controversy on the topic of sodium in the heart. The present review focuses on cardiac Na+/Ca2+ exchange (NCX) and Na+/K+-ATPase (NKA). While the relevance of Ca2+ homeostasis in cardiac function has been extensively investigated, the role of Na+ regulation in shaping heart function is often overlooked. Small changes in the cytoplasmic Na+ content have multiple effects on the heart by influencing intracellular Ca2+ and pH levels thereby modulating heart contractility. Therefore it is essential for heart cells to maintain Na+ homeostasis. Among the proteins that accomplish this task are the Na+/Ca2+ exchanger (NCX) and the Na+/K+ pump (NKA). By transporting three Na+ ions into the cytoplasm in exchange for one Ca2+ moved out, NCX is one of the main Na+ influx mechanisms in cardiomyocytes. Acting in the opposite direction, NKA moves Na+ ions from the cytoplasm to the extracellular space against their gradient by utilizing the energy released from ATP hydrolysis. A fine balance between these two processes controls the net amount of intracellular Na+ and aberrations in either of these two systems can have a large impact on cardiac contractility. Due to the relevant role of these two proteins in Na+ homeostasis, the emphasis of this review is on recent developments regarding the cardiac Na+/Ca2+ exchanger (NCX1) and Na+/K+ pump and the controversies that still persist in the field.
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Affiliation(s)
- Michael J Shattock
- King's College London BHF Centre of Excellence, The Rayne Institute, St Thomas' Hospital, London, SE1 7EH, UK
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Manoharan P, Radzyukevich TL, Hakim Javadi H, Stiner CA, Landero Figueroa JA, Lingrel JB, Heiny JA. Phospholemman is not required for the acute stimulation of Na⁺-K⁺-ATPase α₂-activity during skeletal muscle fatigue. Am J Physiol Cell Physiol 2015; 309:C813-22. [PMID: 26468207 DOI: 10.1152/ajpcell.00205.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 09/08/2015] [Indexed: 11/22/2022]
Abstract
The Na(+)-K(+)-ATPase α2-isoform in skeletal muscle is rapidly stimulated during muscle use and plays a critical role in fatigue resistance. The acute mechanisms that stimulate α2-activity are not completely known. This study examines whether phosphorylation of phospholemman (PLM/FXYD1), a regulatory subunit of Na(+)-K(+)-ATPase, plays a role in the acute stimulation of α2 in working muscles. Mice lacking PLM (PLM KO) have a normal content of the α2-subunit and show normal exercise capacity, in contrast to the greatly reduced exercise capacity of mice that lack α2 in the skeletal muscles. Nerve-evoked contractions in vivo did not induce a change in total PLM or PLM phosphorylated at Ser63 or Ser68, in either WT or PLM KO. Isolated muscles of PLM KO mice maintain contraction and resist fatigue as well as wild type (WT). Rb(+) transport by the α2-Na(+)-K(+)-ATPase is stimulated to the same extent in contracting WT and contracting PLM KO muscles. Phosphorylation of sarcolemmal membranes prepared from WT but not PLM KO skeletal muscles stimulates the activity of both α1 and α2 in a PLM-dependent manner. The stimulation occurs by an increase in Na(+) affinity without significant change in Vmax and is more effective for α1 than α2. These results demonstrate that phosphorylation of PLM is capable of stimulating the activity of both isozymes in skeletal muscle; however, contractile activity alone is not sufficient to induce PLM phosphorylation. Importantly, acute stimulation of α2, sufficient to support exercise and oppose fatigue, does not require PLM or its phosphorylation.
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Affiliation(s)
- Palanikumar Manoharan
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, Ohio
| | - Tatiana L Radzyukevich
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio; and
| | - Hesamedin Hakim Javadi
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio; and
| | - Cory A Stiner
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio
| | | | - Jerry B Lingrel
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, Ohio
| | - Judith A Heiny
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio; and
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DiFranco M, Hakimjavadi H, Lingrel JB, Heiny JA. Na,K-ATPase α2 activity in mammalian skeletal muscle T-tubules is acutely stimulated by extracellular K+. ACTA ACUST UNITED AC 2015; 146:281-94. [PMID: 26371210 PMCID: PMC4586590 DOI: 10.1085/jgp.201511407] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 08/21/2015] [Indexed: 11/20/2022]
Abstract
The K+ affinity of the Na,K-ATPase α2 isoform matches its activity to the range of extracellular K+ concentrations in the T-tubules at rest and during contraction, maintaining the excitability of active muscle. The Na,K-ATPase α2 isoform is the predominant Na,K-ATPase in adult skeletal muscle and the sole Na,K-ATPase in the transverse tubules (T-tubules). In quiescent muscles, the α2 isozyme operates substantially below its maximal transport capacity. Unlike the α1 isoform, the α2 isoform is not required for maintaining resting ion gradients or the resting membrane potential, canonical roles of the Na,K-ATPase in most other cells. However, α2 activity is stimulated immediately upon the start of contraction and, in working muscles, its contribution is crucial to maintaining excitation and resisting fatigue. Here, we show that α2 activity is determined in part by the K+ concentration in the T-tubules, through its K+ substrate affinity. Apparent K+ affinity was determined from measurements of the K1/2 for K+ activation of pump current in intact, voltage-clamped mouse flexor digitorum brevis muscle fibers. Pump current generated by the α2 Na,K-ATPase, Ip, was identified as the outward current activated by K+ and inhibited by micromolar ouabain. Ip was outward at all potentials studied (−90 to −30 mV) and increased with depolarization in the subthreshold range, −90 to −50 mV. The Q10 was 2.1 over the range of 22–37°C. The K1/2,K of Ip was 4.3 ± 0.3 mM at −90 mV and was relatively voltage independent. This K+ affinity is lower than that reported for other cell types but closely matches the dynamic range of extracellular K+ concentrations in the T-tubules. During muscle contraction, T-tubule luminal K+ increases in proportion to the frequency and duration of action potential firing. This K1/2,K predicts a low fractional occupancy of K+ substrate sites at the resting extracellular K+ concentration, with occupancy increasing in proportion to the frequency of membrane excitation. The stimulation of preexisting pumps by greater K+ site occupancy thus provides a rapid mechanism for increasing α2 activity in working muscles.
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Affiliation(s)
- Marino DiFranco
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095
| | - Hesamedin Hakimjavadi
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267
| | - Jerry B Lingrel
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267
| | - Judith A Heiny
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267
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Naticchioni M, Karani R, Smith MA, Onusko E, Robbins N, Jiang M, Radzyukevich T, Fulford L, Gao X, Apel R, Heiny J, Rubinstein J, Koch SE. Transient Receptor Potential Vanilloid 2 Regulates Myocardial Response to Exercise. PLoS One 2015; 10:e0136901. [PMID: 26356305 PMCID: PMC4565583 DOI: 10.1371/journal.pone.0136901] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 08/10/2015] [Indexed: 01/14/2023] Open
Abstract
The myocardial response to exercise is an adaptive mechanism that permits the heart to maintain cardiac output via improved cardiac function and development of hypertrophy. There are many overlapping mechanisms via which this occurs with calcium handling being a crucial component of this process. Our laboratory has previously found that the stretch sensitive TRPV2 channels are active regulators of calcium handling and cardiac function under baseline conditions based on our observations that TRPV2-KO mice have impaired cardiac function at baseline. The focus of this study was to determine the cardiac function of TRPV2-KO mice under exercise conditions. We measured skeletal muscle at baseline in WT and TRPV2-KO mice and subjected them to various exercise protocols and measured the cardiac response using echocardiography and molecular markers. Our results demonstrate that the TRPV2-KO mouse did not tolerate forced exercise although they became increasingly exercise tolerant with voluntary exercise. This occurs as the cardiac function deteriorates further with exercise. Thus, our conclusion is that TRPV2-KO mice have impaired cardiac functional response to exercise.
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Affiliation(s)
- Mindi Naticchioni
- Department of Internal Medicine, Division of Cardiovascular Health & Disease, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Rajiv Karani
- Department of Internal Medicine, Division of Cardiovascular Health & Disease, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Margaret A. Smith
- Department of Internal Medicine, Division of Cardiovascular Health & Disease, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Evan Onusko
- Department of Internal Medicine, Division of Cardiovascular Health & Disease, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Nathan Robbins
- Department of Internal Medicine, Division of Cardiovascular Health & Disease, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Min Jiang
- Department of Internal Medicine, Division of Cardiovascular Health & Disease, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Tatiana Radzyukevich
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Logan Fulford
- Department of Internal Medicine, Division of Cardiovascular Health & Disease, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Xu Gao
- Department of Internal Medicine, Division of Cardiovascular Health & Disease, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Ryan Apel
- Department of Internal Medicine, Division of Cardiovascular Health & Disease, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Judith Heiny
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Jack Rubinstein
- Department of Internal Medicine, Division of Cardiovascular Health & Disease, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Sheryl E. Koch
- Department of Internal Medicine, Division of Cardiovascular Health & Disease, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
- * E-mail:
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Isoform-specific Na,K-ATPase alterations precede disuse-induced atrophy of rat soleus muscle. BIOMED RESEARCH INTERNATIONAL 2015; 2015:720172. [PMID: 25654120 PMCID: PMC4309216 DOI: 10.1155/2015/720172] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 10/18/2014] [Indexed: 11/17/2022]
Abstract
This study examines the isoform-specific effects of short-term hindlimb suspension (HS) on the Na,K-ATPase in rat soleus muscle. Rats were exposed to 24–72 h of HS and we analyzed the consequences on soleus muscle mass and contractile parameters; excitability and the resting membrane potential (RMP) of muscle fibers; the electrogenic activity, protein, and mRNA content of the α1 and α2 Na,K-ATPase; the functional activity and plasma membrane localization of the α2 Na,K-ATPase. Our results indicate that 24–72 h of HS specifically decreases the electrogenic activity of the Na,K-ATPase α2 isozyme and the RMP of soleus muscle fibers. This decrease occurs prior to muscle atrophy or any change in contractile parameters. The α2 mRNA and protein content increased after 24 h of HS and returned to initial levels at 72 h; however, even the increased content was not able to restore α2 enzyme activity in the disused soleus muscle. There was no change in the membrane localization of α2 Na,K-ATPase. The α1 Na,K-ATPase electrogenic activity, protein and mRNA content did not change. Our findings suggest that skeletal muscle use is absolutely required for α2 Na,K-ATPase transport activity and provide the first evidence that Na,K-ATPase alterations precede HS-induced muscle atrophy.
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32
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Krivoi II. Functional interactions of Na,K-ATPase with molecular environment. Biophysics (Nagoya-shi) 2014. [DOI: 10.1134/s000635091405011x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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Kumar A, De T, Mishra A, Mishra AK. Oleandrin: A cardiac glycosides with potent cytotoxicity. Pharmacogn Rev 2014; 7:131-9. [PMID: 24347921 PMCID: PMC3841991 DOI: 10.4103/0973-7847.120512] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Revised: 05/29/2013] [Accepted: 10/25/2013] [Indexed: 11/17/2022] Open
Abstract
Cardiac glycosides are used in the treatment of congestive heart failure and arrhythmia. Current trend shows use of some cardiac glycosides in the treatment of proliferative diseases, which includes cancer. Nerium oleander L. is an important Chinese folk medicine having well proven cardio protective and cytotoxic effect. Oleandrin (a toxic cardiac glycoside of N. oleander L.) inhibits the activity of nuclear factor kappa-light-chain-enhancer of activated B chain (NF-κB) in various cultured cell lines (U937, CaOV3, human epithelial cells and T cells) as well as it induces programmed cell death in PC3 cell line culture. The mechanism of action includes improved cellular export of fibroblast growth factor-2, induction of apoptosis through Fas gene expression in tumor cells, formation of superoxide radicals that cause tumor cell injury through mitochondrial disruption, inhibition of interleukin-8 that mediates tumorigenesis and induction of tumor cell autophagy. The present review focuses the applicability of oleandrin in cancer treatment and concerned future perspective in the area.
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Affiliation(s)
- Arvind Kumar
- Department of Pharmaceutical Chemistry, Central Facility of Instrumentation, School of Pharmaceutical Sciences, IFTM University, Lodhipur, Rajput, Moradabad, Uttar Pradesh, India
| | - Tanmoy De
- Department of Pharmaceutical Chemistry, Central Facility of Instrumentation, School of Pharmaceutical Sciences, IFTM University, Lodhipur, Rajput, Moradabad, Uttar Pradesh, India
| | - Amrita Mishra
- Department of Pharmaceutical Chemistry, Central Facility of Instrumentation, School of Pharmaceutical Sciences, IFTM University, Lodhipur, Rajput, Moradabad, Uttar Pradesh, India
| | - Arun K Mishra
- Department of Pharmaceutical Chemistry, Central Facility of Instrumentation, School of Pharmaceutical Sciences, IFTM University, Lodhipur, Rajput, Moradabad, Uttar Pradesh, India
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34
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Radzyukevich TL, Neumann JC, Rindler TN, Oshiro N, Goldhamer DJ, Lingrel JB, Heiny JA. Tissue-specific role of the Na,K-ATPase α2 isozyme in skeletal muscle. J Biol Chem 2012. [PMID: 23192345 DOI: 10.1074/jbc.m112.424663] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Na,K-ATPase α2 isozyme is the major Na,K-ATPase of mammalian skeletal muscle. This distribution is unique compared with most other cells, which express mainly the Na,K-ATPase α1 isoform, but its functional significance is not known. We developed a gene-targeted mouse (skα2(-/-)) in which the α2 gene (Atp1a2) is knocked out in the skeletal muscles, and examined the consequences for exercise performance, membrane potentials, contractility, and muscle fatigue. Targeted knockout was confirmed by genotyping, Western blot, and immunohistochemistry. Skeletal muscle cells of skα2(-/-) mice completely lack α2 protein and have no α2 in the transverse tubules, where its expression is normally enhanced. The α1 isoform, which is normally enhanced on the outer sarcolemma, is up-regulated 2.5-fold without change in subcellular targeting. skα2(-/-) mice are apparently normal under basal conditions but show significantly reduced exercise capacity when challenged to run. Their skeletal muscles produce less force, are unable to increase force to match demand, and show significantly increased susceptibility to fatigue. The impairments affect both fast and slow muscle types. The subcellular targeting of α2 to the transverse tubules is important for this role. Increasing Na,K-ATPase α1 content cannot fully compensate for the loss of α2. The increased fatigability of skα2(-/-) muscles is reproduced in control extensor digitorum longus muscles by selectively inhibiting α2 enzyme activity with ouabain. These results demonstrate that the Na,K-ATPase α2 isoform performs an acute, isoform-specific role in skeletal muscle. Its activity is regulated by muscle use and enables working muscles to maintain contraction and resist fatigue.
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Affiliation(s)
- Tatiana L Radzyukevich
- Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0576 USA
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35
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Sibarov DA, Bolshakov AE, Abushik PA, Krivoi II, Antonov SM. Na+,K+-ATPase Functionally Interacts with the Plasma Membrane Na+,Ca2+ Exchanger to Prevent Ca2+ Overload and Neuronal Apoptosis in Excitotoxic Stress. J Pharmacol Exp Ther 2012; 343:596-607. [DOI: 10.1124/jpet.112.198341] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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37
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Akimova OA, Van Huysse J, Tremblay J, Orlov SN. Low efficiency of functional translation of ouabain-resistant α2-Na(+),K(+)-ATPase mRNA in C7-MDCK epithelial cells. Can J Physiol Pharmacol 2011; 90:83-8. [PMID: 22188474 DOI: 10.1139/y11-113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Na(+),K(+)-ATPase is a heterodimer consisting of catalytic α1-α4 and regulatory β1-β3 subunits. Recently, we reported that transfection with ouabain-resistant α1R-Na(+),K(+)-ATPase rescues renal epithelial C7-MDCK cells exclusively expressing the ouabain-sensitive α1S-isoform from the cytotoxic action of ouabain. To explore the role of α2 subunit in ion transport and cytotoxic action of ouabain, we compared the effect of ouabain on K(+) ((86)Rb) influx and the survival of ouabain-treated C7-MDCK cells stably transfected with α1R- and α2R-Na(+),K(+)-ATPase. α2R mRNA in transfected cells was ∼8-fold more abundant than α1R mRNA, whereas immunoreactive α2R protein content was 5-fold lower than endogenous α1S protein. A concentration of 10 µmol/L ouabain led to complete inhibition of (86)Rb influx both in mock- and α2R-transfected cells, whereas maximal inhibition of (86)Rb influx in α1R-transfectd cells was observed at 1000 µmol/L ouabain. In contrast to the massive death of mock- and α2R-transfected cells exposed to 3 µmol/L ouabain , α1R-cells survived after 24 h incubation with 1000 µmol/L ouabain. Thus, our results show that unlike α1R, the presence of α2R-Na(+),K(+)-ATPase subunit mRNA and immunoreactive protein does not contribute to Na(+)/K(+) pump activity, and does not rescue C7-MDCK cells from the cytotoxic action of ouabain. Our results also suggest that the lack of impact of transfected α2-Na(+),K(+)-ATPase on Na(+)/K(+) pump activity and cell survival can be attributed to the low efficiency of its translation and (or) delivery to the plasma membrane of renal epithelial cells.
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Affiliation(s)
- Olga A Akimova
- Research Centre, Centre hospitalier de l'Université de Montréal (CRCHUM) - Technopôle Angus, 2901 Rachel East, Montreal, QC H1W 4A4, Canada
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Schaefer TL, Lingrel JB, Moseley AE, Vorhees CV, Williams MT. Targeted mutations in the Na,K-ATPase α 2 isoform confer ouabain resistance and result in abnormal behavior in mice. Synapse 2010; 65:520-31. [PMID: 20936682 DOI: 10.1002/syn.20870] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 09/09/2010] [Indexed: 01/09/2023]
Abstract
Sodium and potassium-activated adenosine triphosphatases (Na,K-ATPase) are ubiquitous, participate in osmotic balance and membrane potential, and are composed of α, β, and γ subunits. The α subunit is required for the catalytic and transport properties of the enzyme and contains binding sites for cations, ATP, and digitalis-like compounds including ouabain. There are four known α isoforms; three that are expressed in the CNS in a regional and cell-specific manner. The α2 isoform is most commonly found in astrocytes, pyramidal cells of the hippocampus in adults, and developmentally in several other neuronal types. Ouabain-like compounds are thought to be produced endogenously in mammals, bind the Na,K-ATPase, and function as a stress-related hormone, however, the impact of the Na,K-ATPase ouabain binding site on neurobehavioral function is largely unknown. To determine if the ouabain binding site of the α2 isoform plays a physiological role in CNS function, we examined knock-in mice in which the normally ouabain-sensitive α2 isoform was made resistant (α2(R/R) ) while still retaining basal Na,K-ATPase enzymatic function. Egocentric learning (Cincinnati water maze) was impaired in adult α2(R/R) mice compared to wild type (WT) mice. They also exhibited decreased locomotor activity in a novel environment and increased responsiveness to a challenge with an indirect sympathomimetic agonist (methamphetamine) relative to WT mice. The α2(R/R) mice also demonstrated a blunted acoustic startle reflex and a failure to habituate to repeated acoustic stimuli. The α2(R/R) mice showed no evidence of altered anxiety (elevated zero maze) nor were they impaired in spatial learning or memory in the Morris water maze and neither group could learn in a large Morris maze. These results suggest that the ouabain binding site is involved in specific types of learning and the modulation of dopamine-mediated locomotor behavior.
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Affiliation(s)
- Tori L Schaefer
- Division of Neurology, Cincinnati Children's Research Foundation and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45229-3039, USA
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Heiny JA, Kravtsova VV, Mandel F, Radzyukevich TL, Benziane B, Prokofiev AV, Pedersen SE, Chibalin AV, Krivoi II. The nicotinic acetylcholine receptor and the Na,K-ATPase alpha2 isoform interact to regulate membrane electrogenesis in skeletal muscle. J Biol Chem 2010; 285:28614-26. [PMID: 20595385 DOI: 10.1074/jbc.m110.150961] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The nicotinic acetylcholine receptor (nAChR) and the Na,K-ATPase functionally interact in skeletal muscle (Krivoi, I. I., Drabkina, T. M., Kravtsova, V. V., Vasiliev, A. N., Eaton, M. J., Skatchkov, S. N., and Mandel, F. (2006) Pflugers Arch. 452, 756-765; Krivoi, I., Vasiliev, A., Kravtsova, V., Dobretsov, M., and Mandel, F. (2003) Ann. N.Y. Acad. Sci. 986, 639-641). In this interaction, the specific binding of nanomolar concentrations of nicotinic agonists to the nAChR stimulates electrogenic transport by the Na,K-ATPase alpha2 isozyme, causing membrane hyperpolarization. This study examines the molecular nature and membrane localization of this interaction. Stimulation of Na,K-ATPase activity by the nAChR does not require ion flow through open nAChRs. It can be induced by nAChR desensitization alone, in the absence of nicotinic agonist, and saturates when the nAChR is fully desensitized. It is enhanced by noncompetitive blockers of the nAChR (proadifen, QX-222), which promote non-conducting or desensitized states; and retarded by tetracaine, which stabilizes the resting nAChR conformation. The interaction operates at the neuromuscular junction as well as on extrajunctional sarcolemma. The Na,K-ATPase alpha2 isozyme is enriched at the postsynaptic neuromuscular junction and co-localizes with nAChRs. The nAChR and Na,K-ATPase alpha subunits specifically coimmunoprecipitate with each other, phospholemman, and caveolin-3. In a purified membrane preparation from Torpedo californica enriched in nAChRs and the Na,K-ATPase, a ouabain-induced conformational change of the Na,K-ATPase enhances a conformational transition of the nAChR to a desensitized state. These results suggest a mechanism by which the nAChR in a desensitized state with high apparent affinity for agonist interacts with the Na,K-ATPase to stimulate active transport. The interaction utilizes a membrane-delimited complex involving protein-protein interactions, either directly or through additional protein partners. This interaction is expected to enhance neuromuscular transmission and muscle excitation.
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Affiliation(s)
- Judith A Heiny
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
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40
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Lingrel JB. The physiological significance of the cardiotonic steroid/ouabain-binding site of the Na,K-ATPase. Annu Rev Physiol 2010; 72:395-412. [PMID: 20148682 DOI: 10.1146/annurev-physiol-021909-135725] [Citation(s) in RCA: 220] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The Na,K-ATPase is the membrane "pump" that generates the Na(+) and K(+) gradients across the plasma membrane that drives many physiological processes. This enzyme is highly sensitive to inhibition by cardiotonic steroids, most notably the digitalis/ouabain class of compounds, which have been used for centuries to treat congestive heart failure and arrhythmias. The amino acids that constitute the ouabain-binding site are highly conserved across the evolutionary spectrum. This could be fortuitous or could result from this site being conserved because it has an important biological function. New physiological approaches using genetically engineered mice are being used to define the biological significance of the "receptor function" of the Na,K-ATPase and its regulation by potential endogenous cardiotonic steroid-like compounds. These studies extend the reach of earlier studies involving the biochemical purification of endogenous regulatory ligands.
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Affiliation(s)
- Jerry B Lingrel
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0524, USA.
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Akimova OA, Tremblay J, Van Huysse JW, Hamet P, Orlov SN. Cardiotonic steroid-resistant alpha1-Na+,K+-ATPase rescues renal epithelial cells from the cytotoxic action of ouabain: evidence for a Nai+,Ki+ -independent mechanism. Apoptosis 2010; 15:55-62. [PMID: 19949978 DOI: 10.1007/s10495-009-0429-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mechanisms underlying the tissue-specific impact of cardiotonic steroids (CTS) on cell survival and death remain poorly understood. This study examines the role of Na(+),K(+)-ATPase alpha subunits in death of Madin-Darby canine kidney (MDCK) cells evoked by 24-h exposure to ouabain. MDCK cells expressing a variant of the alpha1 isoform, CTS-sensitive alpha1S, were stably transfected with a cDNA encoding CTS-resistant alpha1R-Na(+),K(+)-ATPase, whose expression was confirmed by RT-PCR. In mock-transfected and alpha1R-cells, maximal inhibition of (86)Rb influx was observed at 10 and 1000 muM ouabain, respectively, thus confirming high abundance of alpha1R-Na(+),K(+)-ATPase in these cells. Six-hour treatment of alpha1R-cells with 1000 muM ouabain led to the same elevation of the [Na(+)](i)/[K(+)](i) ratio that was detected in mock-transfected cells treated with 3 muM ouabain. However, in contrast to the massive death of mock-transfected cells exposed to 3 muM ouabain, alpha1R-cells survived after 24-h incubation with 1000 muM ouabain. Inversion of the [Na(+)](i)/[K(+)](i) ratio evoked by Na(+),K(+)-ATPase inhibition in K(+)-free medium did not affect survival of alpha1R-cells but increased their sensitivity to ouabain. Our results show that the alpha1R subunit rescues MDCK cells from the cytotoxic action of CTS independently of inhibition of Na(+),K(+)-ATPase-mediated Na(+) and K(+) fluxes and inversion of the [Na(+)](i)/[K(+)](i) ratio.
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Affiliation(s)
- Olga A Akimova
- Centre de Recherche, Centre Hospitalier de l'Université de Montréal, Technopôle Angus, 2901 Rachel Est, Montreal, QC H1W 4A4, Canada.
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