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Gusev K, Shalygin A, Kolesnikov D, Shuyskiy L, Makeenok S, Glushankova L, Sivak K, Yakovlev K, Orshanskaya Y, Wang G, Bakhtyukov A, Derkach K, Shpakov A, Kaznacheyeva E. Reorganization and Suppression of Store-Operated Calcium Entry in Podocytes of Type 2 Diabetic Rats. Int J Mol Sci 2023; 24:ijms24087259. [PMID: 37108424 PMCID: PMC10139047 DOI: 10.3390/ijms24087259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 04/07/2023] [Accepted: 04/12/2023] [Indexed: 04/29/2023] Open
Abstract
Type 2 diabetes mellitus (DM2) is a widespread metabolic disorder that results in podocyte damage and diabetic nephropathy. Previous studies demonstrated that TRPC6 channels play a pivotal role in podocyte function and their dysregulation is associated with development of different kidney diseases including nephropathy. Here, using single channel patch clamp technique, we demonstrated that non-selective cationic TRPC6 channels are sensitive to the Ca2+ store depletion in human podocyte cell line Ab8/13 and in freshly isolated rat glomerular podocytes. Ca2+ imaging indicated the involvement of ORAI and sodium-calcium exchanger in Ca2+ entry induced upon store depletion. In male rats fed a high-fat diet combined with a low-dose streptozotocin injection, which leads to DM2 development, we observed the reduction of a store-operated Ca2+ entry (SOCE) in rat glomerular podocytes. This was accompanied by a reorganization of store-operated Ca2+ influx such that TRPC6 channels lost their sensitivity to Ca2+ store depletion and ORAI-mediated Ca2+ entry was suppressed in TRPC6-independent manner. Altogether our data provide new insights into the mechanism of SOCE organization in podocytes in the norm and in pathology, which should be taken into account when developing pharmacological treatment of the early stages of diabetic nephropathy.
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Affiliation(s)
- Konstantin Gusev
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
| | - Alexey Shalygin
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
| | - Dmitrii Kolesnikov
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
| | - Leonid Shuyskiy
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
| | - Sofia Makeenok
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
| | - Lyubov Glushankova
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
| | - Konstantin Sivak
- Smorodintsev Research Institute of Influenza WHO National Influenza Centre of Russia, St. Petersburg 197376, Russia
| | - Kirill Yakovlev
- Smorodintsev Research Institute of Influenza WHO National Influenza Centre of Russia, St. Petersburg 197376, Russia
| | - Yana Orshanskaya
- Smorodintsev Research Institute of Influenza WHO National Influenza Centre of Russia, St. Petersburg 197376, Russia
| | - Guanghui Wang
- Department of Pharmacology, College of Pharmaceutic Sciences, Soochow University, Suzhou 215031, China
| | - Andrey Bakhtyukov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russia
| | - Kira Derkach
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russia
| | - Alexander Shpakov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russia
| | - Elena Kaznacheyeva
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
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2
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Okonski R, Zheng YM, Di Mise A, Wang YX. Reciprocal Correlations of Inflammatory and Calcium Signaling in Asthma Pathogenesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1303:319-331. [PMID: 33788200 DOI: 10.1007/978-3-030-63046-1_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Asthma is a chronic disease characterized by airway hyperresponsiveness, which can be caused by exposure to an allergen, spasmogen, or be induced by exercise. Despite its prevalence, the exact mechanisms by which the airway becomes hyperresponsive in asthma are not fully understood. There is evidence that myosin light-chain kinase is overexpressed, with a concomitant downregulation of myosin light-chain phosphatase in the airway smooth muscle, leading to sustained contraction. Additionally, the sarco/endoplasmic reticulum ATPase may be affected by inflammatory cytokines, such as IL-4, IL-5, IL-13, and TNF-α, which are all associated with asthmatic airway inflammation. IL-13 and TNF-α seem to promote sodium/calcium exchanger 1 overexpression as well. Anyhow, the exact mechanisms beyond these dysregulations need to be clarified. Of note, multiple studies show an association between asthma and the ORMLD3 gene, opening new perspectives to future potential gene therapies. Currently, several treatments are available for asthma, although many of them have systemic side effects, or are not effective in patients with severe asthma. Furthering our knowledge on the molecular and pathophysiological mechanisms of asthma plays a pivotal role for the development of new and more targeted treatments for patients who cannot totally benefit from the current therapies.
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Affiliation(s)
- Ryan Okonski
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York, USA
| | - Yun-Min Zheng
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York, USA
| | - Annarita Di Mise
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York, USA. .,Department of Biosciences, Biotechnologies e Biopharmaceutics, University of Bari, Bari, Italy.
| | - Yong-Xiao Wang
- Department of Molecular and Cellular Physiology, Albany Medical College, Albany, New York, USA.
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3
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Kaymak E, Akin AT, Tufan E, Başaran KE, Taheri S, Özdamar S, Yakan B. The effect of chloroquine on the TRPC1, TRPC6, and CaSR in the pulmonary artery smooth muscle cells in hypoxia-induced experimental pulmonary artery hypertension. J Biochem Mol Toxicol 2020; 35:e22636. [PMID: 32956540 DOI: 10.1002/jbt.22636] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 07/30/2020] [Accepted: 09/09/2020] [Indexed: 01/10/2023]
Abstract
Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by a constant high pulmonary artery pressure and the remodeling of the vessel. Chloroquine (CLQ) has been observed to inhibit calcium influx. The aim of this study is to investigate the effect of CLQ on transient receptor cationic proteins (TRPC1 and TRPC6) and extracellular calcium-sensitive receptor (CaSR) in a hypoxic PAH model. In this study, 8- to 12-week-old 32 male Wistar albino rats, weighing 200 to 300 g, were used. The rats were studied in four groups, including normoxy control, n = 8; normoxy CLQ (50 mg/kg/28 d), n = 8; hypoxia (HX; 10% oxygen/28 d) control, n = 8; and HX (10% oxygen/28 d) + CLQ (50 mg/kg), N = 8. Pulmonary arterial medial wall thickness, pulmonary arteriole wall, TRPC1, TRPC6, and CaSR expressions were evaluated by immunohistochemistry, polymerase chain reaction, and enzyme-linked immunosorbent assay methods. At the end of the experiment, a statistically significant increase in the medial wall thickness was observed in the hypoxic group as compared with the control group. However, in the HX + CLQ group, there was a statistically significant decrease in the vessel medial wall as compared with the HX group. In the TRPC1-, TRPC6-, and CaSR-immunopositive cell numbers, messenger RNA expressions and biochemical results showed an increase in the HX group, whereas they were decreased in the HX + CLQ group. The inhibitory effect of CLQ on calcium receptors in arterioles was observed in PAH.
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Affiliation(s)
- Emin Kaymak
- Department of Histology and Embryology, Yozgat Bozok University, Yozgat, Turkey
| | | | - Esra Tufan
- Department of Physiology, Erciyes University, Kayseri, Turkey
| | | | - Serpil Taheri
- Department of Medical Biology, Erciyes University, Kayseri, Turkey
| | - Saim Özdamar
- Department of Histology and Embryology, Pamukkale University, Denizli, Turkey
| | - Birkan Yakan
- Department of Histology and Embryology, Erciyes University, Kayseri, Turkey
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4
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BRAF and NRAS mutated melanoma: Different Ca 2+ responses, Na +/Ca 2+ exchanger expression, and sensitivity to inhibitors. Cell Calcium 2020; 90:102241. [PMID: 32562975 DOI: 10.1016/j.ceca.2020.102241] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 05/27/2020] [Accepted: 06/04/2020] [Indexed: 01/10/2023]
Abstract
Calcium is a ubiquitous intracellular second messenger, playing central roles in the regulation of several biological processes. Alterations in Ca2+ homeostasis and signaling are an important feature of tumor cells to acquire proliferative and survival advantages, which include structural and functional changes in storage capacity, channels, and pumps. Here, we investigated the differences in Ca2+ homeostasis in vemurafenib-responsive and non-responsive melanoma cells. Also, the expression of the Na+/Ca2+ exchanger (NCX) and the impact of its inhibition were studied. For this, it was used B-RAFV600E and NRASQ61R-mutated human melanoma cells. The intracellular Ca2+ chelator BAPTA-AM decreased the viability of SK-MEL-147 but not of SK-MEL-19 and EGTA sensitized NRASQ61R-mutated cells to vemurafenib. These cells also presented a smaller response to thapsargin and ionomycin regarding the cytosolic Ca2+ levels in relation to SK-MEL-19, which was associated to an increased expression of NCX1, NO basal levels, and sensitivity to NCX inhibitors. These data highlight the differences between B-RAFV600E and NRASQ61R-mutated melanoma cells in response to Ca2+ stimuli and point to the potential combination of clinically used chemotherapeutic drugs, including vemurafenib, with NCX inhibitors as a new therapeutic strategy to the treatment of melanoma.
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5
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Wen J, Meng X, Xuan B, Zhou T, Gao H, Dong H, Wang Y. Na +/Ca 2+ Exchanger 1 in Airway Smooth Muscle of Allergic Inflammation Mouse Model. Front Pharmacol 2018; 9:1471. [PMID: 30618761 PMCID: PMC6300471 DOI: 10.3389/fphar.2018.01471] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 11/30/2018] [Indexed: 11/13/2022] Open
Abstract
Cytosolic free Ca2+ ([Ca2+]cyt) is essential for airway contraction, secretion and remodeling. [Ca2+]cyt homeostasis is controlled by several critical molecules, one of which is the Na+/Ca2+ exchanger 1 (NCX1) in the plasma membrane. Since little is currently known about NCX1 in the airway smooth muscle and its involvement in airway diseases, the present study was designed to investigate the expression and function of NCX1 in normal airway smooth muscle and its relevance to airway inflammation. Western blot analysis, tracheal smooth muscle contraction, and [Ca2+]cyt measurements were performed in mouse tracheal smooth muscle tissues and primary airway smooth muscle cell cultures. Additional studies were performed in a mouse model of allergic airway inflammation. Our data showed that NCX1 proteins were expressed in the human bronchial smooth muscle cells (HBSMCs), murine airway and whole lung. Carbachol raised [Ca2+]cyt in mouse tracheal smooth muscle cells and induced murine tracheal contraction, all of which were significantly attenuated by KB-R7943, a selective NCX inhibitor. Removal of extracellular Na+ increased [Ca2+]cyt in HBSMCs and mouse tracheal SMCs, which was dependent on extracellular Ca2+ and sensitive to KB-R7943. TNF-α treatment of HBSMCs significantly upregulated mRNA and protein expression of NCX1 and enhanced NCX activity. Finally, KB-R7943 abolished the airway hyperresponsiveness to methacholine in an ovalbumin-induced mouse model of allergic airway inflammation. Together, these findings indicate that NCX1 in airway smooth muscle may play an important role in the development of airway hyperresponsiveness, and downregulation or inhibition of NCX1 may serve as a potential therapeutic approach for asthma.
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Affiliation(s)
- Jiexia Wen
- Department of Central Laboratory, The First Hospital of Qinhuangdao, Hebei Medical University, Qinhuangdao, China
| | - Xiangcai Meng
- Department of General Surgery, The First Hospital of Qinhuangdao, Hebei Medical University, Qinhuangdao, China
| | - Bin Xuan
- Department of General Surgery, The First Hospital of Qinhuangdao, Hebei Medical University, Qinhuangdao, China
| | - Tao Zhou
- Department of General Surgery, The First Hospital of Qinhuangdao, Hebei Medical University, Qinhuangdao, China
| | - Heran Gao
- Department of General Surgery, The First Hospital of Qinhuangdao, Hebei Medical University, Qinhuangdao, China
| | - Hui Dong
- Department of Central Laboratory, The First Hospital of Qinhuangdao, Hebei Medical University, Qinhuangdao, China
| | - Yimin Wang
- Department of Central Laboratory, The First Hospital of Qinhuangdao, Hebei Medical University, Qinhuangdao, China.,Department of General Surgery, The First Hospital of Qinhuangdao, Hebei Medical University, Qinhuangdao, China
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6
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The Na/K-ATPase Signaling: From Specific Ligands to General Reactive Oxygen Species. Int J Mol Sci 2018; 19:ijms19092600. [PMID: 30200500 PMCID: PMC6163532 DOI: 10.3390/ijms19092600] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 08/10/2018] [Accepted: 08/28/2018] [Indexed: 12/16/2022] Open
Abstract
The signaling function of the Na/K-ATPase has been established for 20 years and is widely accepted in the field, with many excellent reports and reviews not cited here. Even though there is debate about the underlying mechanism, the signaling function is unquestioned. This short review looks back at the evolution of Na/K-ATPase signaling, from stimulation by cardiotonic steroids (also known as digitalis-like substances) as specific ligands to stimulation by reactive oxygen species (ROS) in general. The interplay of cardiotonic steroids and ROS in Na/K-ATPase signaling forms a positive-feedback oxidant amplification loop that has been implicated in some pathophysiological conditions.
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7
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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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8
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Xu N, Cioffi DL, Alexeyev M, Rich TC, Stevens T. Sodium entry through endothelial store-operated calcium entry channels: regulation by Orai1. Am J Physiol Cell Physiol 2014; 308:C277-88. [PMID: 25428882 DOI: 10.1152/ajpcell.00063.2014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Orai1 interacts with transient receptor potential protein of the canonical subfamily (TRPC4) and contributes to calcium selectivity of the endothelial cell store-operated calcium entry current (ISOC). Orai1 silencing increases sodium permeability and decreases membrane-associated calcium, although it is not known whether Orai1 is an important determinant of cytosolic sodium transitions. We test the hypothesis that, upon activation of store-operated calcium entry channels, Orai1 is a critical determinant of cytosolic sodium transitions. Activation of store-operated calcium entry channels transiently increased cytosolic calcium and sodium, characteristic of release from an intracellular store. The sodium response occurred more abruptly and returned to baseline more rapidly than did the transient calcium rise. Extracellular choline substitution for sodium did not inhibit the response, although 2-aminoethoxydiphenyl borate and YM-58483 reduced it by ∼50%. After this transient response, cytosolic sodium continued to increase due to influx through activated store-operated calcium entry channels. The magnitude of this sustained increase in cytosolic sodium was greater when experiments were conducted in low extracellular calcium and when Orai1 expression was silenced; these two interventions were not additive, suggesting a common mechanism. 2-Aminoethoxydiphenyl borate and YM-58483 inhibited the sustained increase in cytosolic sodium, only in the presence of Orai1. These studies demonstrate that sodium permeates activated store-operated calcium entry channels, resulting in an increase in cytosolic sodium; the magnitude of this response is determined by Orai1.
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Affiliation(s)
- Ningyong Xu
- Department of Pharmacology, University of South Alabama, Mobile, Alabama; Center for Lung Biology, University of South Alabama, Mobile, Alabama
| | - Donna L Cioffi
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, Alabama; Center for Lung Biology, University of South Alabama, Mobile, Alabama
| | - Mikhail Alexeyev
- Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, Alabama; Center for Lung Biology, University of South Alabama, Mobile, Alabama
| | - Thomas C Rich
- Department of Pharmacology, University of South Alabama, Mobile, Alabama; Center for Lung Biology, University of South Alabama, Mobile, Alabama
| | - Troy Stevens
- Department of Pharmacology, University of South Alabama, Mobile, Alabama; Department of Medicine, University of South Alabama, Mobile, Alabama; and Center for Lung Biology, University of South Alabama, Mobile, Alabama
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9
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Blaustein MP. Livin' with NCX and lovin' it: a 45 year romance. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 961:3-15. [PMID: 23224865 PMCID: PMC3884827 DOI: 10.1007/978-1-4614-4756-6_1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
This conference commemorates, almost to the day, the 45th anniversary of the discovery of the Na(+)/Ca(2+) exchanger (NCX). The discovery was serendipitous, as is so often the case with scientific breakthroughs. Indeed, that is what is so fascinating and romantic about scientific research. I will describe the discovery of NCX, but will begin by explaining how I got there, and will then discuss how the discovery influenced my career path.
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10
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Pulina MV, Zulian A, Baryshnikov SG, Linde CI, Karashima E, Hamlyn JM, Ferrari P, Blaustein MP, Golovina VA. Cross talk between plasma membrane Na(+)/Ca (2+) exchanger-1 and TRPC/Orai-containing channels: key players in arterial hypertension. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 961:365-74. [PMID: 23224895 DOI: 10.1007/978-1-4614-4756-6_31] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Arterial smooth muscle (ASM) Na(+)/Ca(2+) exchanger type 1 (NCX1) and TRPC/Orai-containing receptor/store-operated cation channels (ROC/SOC) are clustered with α2 Na(+) pumps in plasma membrane microdomains adjacent to the underlying junctional sarcoplasmic reticulum. This arrangement enables these transport proteins to function as integrated units to help regulate local Na(+) metabolism, Ca(2+) signaling, and arterial tone. They thus influence vascular resistance and blood pressure (BP). For instance, upregulation of NCX1 and TRPC6 has been implicated in the pathogenesis of high BP in several models of essential hypertension. The models include ouabain-induced hypertensive rats, Milan hypertensive rats, and Dahl salt-sensitive hypertensive rats, all of which exhibit elevated plasma ouabain levels. We suggest that these molecular mechanisms are key contributors to the increased vascular resistance ("whole body autoregulation") that elevates BP in essential hypertension. Enhanced expression and function of ASM NCX1 and TRPC/Orai1-containing channels in hypertension implies that these proteins are potential targets for pharmacological intervention.
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Affiliation(s)
- Maria V Pulina
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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11
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Zhang J. New insights into the contribution of arterial NCX to the regulation of myogenic tone and blood pressure. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 961:329-43. [PMID: 23224892 DOI: 10.1007/978-1-4614-4756-6_28] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Plasma membrane protein Na(+)/Ca(2+) exchanger (NCX) in vascular smooth muscle (VSM) cells plays an important role in intracellular Ca(2+) homeostasis, Ca(2+) signaling, and arterial contractility. Recent evidence in intact animals reveals that VSM NCX type 1 (NCX1) is importantly involved in the control of arterial blood pressure (BP) in the normal state and in hypertension. Increased expression of vascular NCX1 has been implicated in human primary pulmonary hypertension and several salt-dependent hypertensive animal models. Our aim is to determine the molecular and physiological mechanisms by which vascular NCX influences vasoconstriction and BP normally and in salt-dependent hypertension. Here, we describe the relative contribution of VSM NCX1 to Ca(2+) signaling and arterial contraction, including recent data from transgenic mice (NCX1(smTg/Tg), overexpressors; NCX1(sm-/-), knockouts) that has begun to elucidate the specific contributions of NCX to BP regulation. Arterial contraction and BP correlate with the level of NCX1 expression in smooth muscle: NCX1(sm-/-) mice have decreased arterial myogenic tone (MT), vasoconstriction, and low BP. NCX1(smTg/Tg) mice have high BP and are more sensitive to salt; their arteries exhibit upregulated transient receptor potential canonical channel 6 (TRPC6) protein, increased MT, and vasoconstriction. These observations suggest that NCX is a key component of certain distinct signaling pathways that activate VSM contraction in response to stretch (i.e., myogenic response) and to activation of certain G-protein-coupled receptors. Arterial NCX expression and mechanisms that control the local (sub-plasma membrane) Na(+) gradient, including cation-selective receptor-operated channels containing TRPC6, regulate arterial Ca(2+) and constriction, and thus BP.
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Affiliation(s)
- Jin Zhang
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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12
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Calcium signaling in vascular smooth muscle cells: from physiology to pathology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:795-810. [PMID: 22453970 DOI: 10.1007/978-94-007-2888-2_35] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Cyclic variations in calcium (Ca(2+)) concentrations, through a process called excitation-contraction coupling, allow regulation of vascular smooth muscle cells contractility and thus modulation of vascular tone and blood pressure. As a second messenger, Ca(2+) also activates signaling cascades leading to transcription factors activation in a process called excitation-transcription coupling. Furthermore, recent evidences indicate an interaction between post-transcriptional regulation by microRNAs (miRNAs) and Ca(2+) signaling. All these actors, which are frequently altered in vascular diseases, will be reviewed here.
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13
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Abstract
It has been known for more than 60 years, and suspected for over 100, that alveolar hypoxia causes pulmonary vasoconstriction by means of mechanisms local to the lung. For the last 20 years, it has been clear that the essential sensor, transduction, and effector mechanisms responsible for hypoxic pulmonary vasoconstriction (HPV) reside in the pulmonary arterial smooth muscle cell. The main focus of this review is the cellular and molecular work performed to clarify these intrinsic mechanisms and to determine how they are facilitated and inhibited by the extrinsic influences of other cells. Because the interaction of intrinsic and extrinsic mechanisms is likely to shape expression of HPV in vivo, we relate results obtained in cells to HPV in more intact preparations, such as intact and isolated lungs and isolated pulmonary vessels. Finally, we evaluate evidence regarding the contribution of HPV to the physiological and pathophysiological processes involved in the transition from fetal to neonatal life, pulmonary gas exchange, high-altitude pulmonary edema, and pulmonary hypertension. Although understanding of HPV has advanced significantly, major areas of ignorance and uncertainty await resolution.
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Affiliation(s)
- J. T. Sylvester
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland; and Division of Asthma, Allergy and Lung Biology, School of Medicine, King's College, London, United Kingdom
| | - Larissa A. Shimoda
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland; and Division of Asthma, Allergy and Lung Biology, School of Medicine, King's College, London, United Kingdom
| | - Philip I. Aaronson
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland; and Division of Asthma, Allergy and Lung Biology, School of Medicine, King's College, London, United Kingdom
| | - Jeremy P. T. Ward
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland; and Division of Asthma, Allergy and Lung Biology, School of Medicine, King's College, London, United Kingdom
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14
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Linde CI, Karashima E, Raina H, Zulian A, Wier WG, Hamlyn JM, Ferrari P, Blaustein MP, Golovina VA. Increased arterial smooth muscle Ca2+ signaling, vasoconstriction, and myogenic reactivity in Milan hypertensive rats. Am J Physiol Heart Circ Physiol 2011; 302:H611-20. [PMID: 22140038 DOI: 10.1152/ajpheart.00950.2011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Milan hypertensive strain (MHS) rats are a genetic model of hypertension with adducin gene polymorphisms linked to enhanced renal tubular Na(+) reabsorption. Recently we demonstrated that Ca(2+) signaling is augmented in freshly isolated mesenteric artery myocytes from MHS rats. This is associated with greatly enhanced expression of Na(+)/Ca(2+) exchanger-1 (NCX1), C-type transient receptor potential (TRPC6) protein, and sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA2) compared with arteries from Milan normotensive strain (MNS) rats. Here, we test the hypothesis that the enhanced Ca(2+) signaling in MHS arterial smooth muscle is directly reflected in augmented vasoconstriction [myogenic and phenylephrine (PE)-evoked responses] in isolated mesenteric small arteries. Systolic blood pressure was higher in MHS (145 ± 1 mmHg) than in MNS (112 ± 1 mmHg; P < 0.001; n = 16 each) rats. Pressurized mesenteric resistance arteries from MHS rats had significantly augmented myogenic tone and reactivity and enhanced constriction to low-dose (1-100 nM) PE. Isolated MHS arterial myocytes exhibited approximately twofold increased peak Ca(2+) signals in response to 5 μM PE or ATP in the absence and presence of extracellular Ca(2+). These augmented responses are consistent with increased vasoconstrictor-evoked sarcoplasmic reticulum (SR) Ca(2+) release and increased Ca(2+) entry, respectively. The increased SR Ca(2+) release correlates with a doubling of inositol 1,4,5-trisphosphate receptor type 1 and tripling of SERCA2 expression. Pressurized MHS arteries also exhibited a ∼70% increase in 100 nM ouabain-induced vasoconstriction compared with MNS arteries. These functional alterations reveal that, in a genetic model of hypertension linked to renal dysfunction, multiple mechanisms within the arterial myocytes contribute to enhanced Ca(2+) signaling and myogenic and vasoconstrictor-induced arterial constriction. MHS rats have elevated plasma levels of endogenous ouabain, which may initiate the protein upregulation and enhanced Ca(2+) signaling. These molecular and functional changes provide a mechanism for the increased peripheral vascular resistance (whole body autoregulation) that underlies the sustained hypertension.
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Affiliation(s)
- Cristina I Linde
- Dept. of Physiology, Univ. of Maryland School of Medicine, 685 W. Baltimore St. HSF1, Rm. 565, Baltimore, MD 21201, USA
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15
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Blaustein MP, Leenen FHH, Chen L, Golovina VA, Hamlyn JM, Pallone TL, Van Huysse JW, Zhang J, Wier WG. How NaCl raises blood pressure: a new paradigm for the pathogenesis of salt-dependent hypertension. Am J Physiol Heart Circ Physiol 2011; 302:H1031-49. [PMID: 22058154 DOI: 10.1152/ajpheart.00899.2011] [Citation(s) in RCA: 175] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Excess dietary salt is a major cause of hypertension. Nevertheless, the specific mechanisms by which salt increases arterial constriction and peripheral vascular resistance, and thereby raises blood pressure (BP), are poorly understood. Here we summarize recent evidence that defines specific molecular links between Na(+) and the elevated vascular resistance that directly produces high BP. In this new paradigm, high dietary salt raises cerebrospinal fluid [Na(+)]. This leads, via the Na(+)-sensing circumventricular organs of the brain, to increased sympathetic nerve activity (SNA), a major trigger of vasoconstriction. Plasma levels of endogenous ouabain (EO), the Na(+) pump ligand, also become elevated. Remarkably, high cerebrospinal fluid [Na(+)]-evoked, locally secreted (hypothalamic) EO participates in a pathway that mediates the sustained increase in SNA. This hypothalamic signaling chain includes aldosterone, epithelial Na(+) channels, EO, ouabain-sensitive α(2) Na(+) pumps, and angiotensin II (ANG II). The EO increases (e.g.) hypothalamic ANG-II type-1 receptor and NADPH oxidase and decreases neuronal nitric oxide synthase protein expression. The aldosterone-epithelial Na(+) channel-EO-α(2) Na(+) pump-ANG-II pathway modulates the activity of brain cardiovascular control centers that regulate the BP set point and induce sustained changes in SNA. In the periphery, the EO secreted by the adrenal cortex directly enhances vasoconstriction via an EO-α(2) Na(+) pump-Na(+)/Ca(2+) exchanger-Ca(2+) signaling pathway. Circulating EO also activates an EO-α(2) Na(+) pump-Src kinase signaling cascade. This increases the expression of the Na(+)/Ca(2+) exchanger-transient receptor potential cation channel Ca(2+) signaling pathway in arterial smooth muscle but decreases the expression of endothelial vasodilator mechanisms. Additionally, EO is a growth factor and may directly participate in the arterial structural remodeling and lumen narrowing that is frequently observed in established hypertension. These several central and peripheral mechanisms are coordinated, in part by EO, to effect and maintain the salt-induced elevation of BP.
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Affiliation(s)
- Mordecai P Blaustein
- Dept. of Physiology, Univ. of Maryland School of Medicine, 655 W. Baltimore St., Baltimore, MD, 21201, USA.
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16
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Liu XR, Zhang MF, Yang N, Liu Q, Wang RX, Cao YN, Yang XR, Sham JSK, Lin MJ. Enhanced store-operated Ca²+ entry and TRPC channel expression in pulmonary arteries of monocrotaline-induced pulmonary hypertensive rats. Am J Physiol Cell Physiol 2011; 302:C77-87. [PMID: 21940663 DOI: 10.1152/ajpcell.00247.2011] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Pulmonary hypertension (PH) is associated with profound vascular remodeling and alterations in Ca(2+) homeostasis in pulmonary arterial smooth muscle cells (PASMCs). Previous studies show that canonical transient receptor potential (TRPC) genes are upregulated and store-operated Ca(2+) entry (SOCE) is augmented in PASMCs of chronic hypoxic rats and patients of pulmonary arterial hypertension (PAH). Here we further examine the involvement of TRPC and SOCE in PH with a widely used rat model of monocrotaline (MCT)-induced PAH. Rats developed severe PAH, right ventricular hypertrophy, and significant increase in store-operated TRPC1 and TRPC4 mRNA and protein in endothelium-denuded pulmonary arteries (PAs) 3 wk after MCT injection. Contraction of PA and Ca(2+) influx in PASMC evoked by store depletion using cyclopiazonic acid (CPA) were enhanced dramatically, consistent with augmented SOCE in the MCT-treated group. The time course of increase in CPA-induced contraction corresponded to that of TRPC1 expression. Endothelin-1 (ET-1)-induced vasoconstriction was also potentiated in PAs of MCT-treated rats. The response was partially inhibited by SOCE blockers, including Gd(3+), La(3+), and SKF-96365, as well as the general TRPC inhibitor BTP-2, suggesting that TRPC-dependent SOCE was involved. Moreover, the ET-1-induced contraction and Ca(2+) response in the MCT group were more susceptible to the inhibition caused by the various SOCE blockers. Hence, our study shows that MCT-induced PAH is associated with increased TRPC expression and SOCE, which are involved in the enhanced vascular reactivity to ET-1, and support the hypothesis that TRPC-dependent SOCE is an important pathway for the development of PH.
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Affiliation(s)
- Xiao-Ru Liu
- Department of Physiology and Pathophysiology, Fujian Medical University, Fuzhou, Fujian Province, People's Republic of China
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17
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Firth AL, Remillard CV, Platoshyn O, Fantozzi I, Ko EA, Yuan JXJ. Functional ion channels in human pulmonary artery smooth muscle cells: Voltage-dependent cation channels. Pulm Circ 2011; 1:48-71. [PMID: 21927714 PMCID: PMC3173772 DOI: 10.4103/2045-8932.78103] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The activity of voltage-gated ion channels is critical for the maintenance of cellular membrane potential and generation of action potentials. In turn, membrane potential regulates cellular ion homeostasis, triggering the opening and closing of ion channels in the plasma membrane and, thus, enabling ion transport across the membrane. Such transmembrane ion fluxes are important for excitation–contraction coupling in pulmonary artery smooth muscle cells (PASMC). Families of voltage-dependent cation channels known to be present in PASMC include voltage-gated K+ (Kv) channels, voltage-dependent Ca2+-activated K+ (Kca) channels, L- and T- type voltage-dependent Ca2+ channels, voltage-gated Na+ channels and voltage-gated proton channels. When cells are dialyzed with Ca2+-free K+- solutions, depolarization elicits four components of 4-aminopyridine (4-AP)-sensitive Kvcurrents based on the kinetics of current activation and inactivation. In cell-attached membrane patches, depolarization elicits a wide range of single-channel K+ currents, with conductances ranging between 6 and 290 pS. Macroscopic 4-AP-sensitive Kv currents and iberiotoxin-sensitive Kca currents are also observed. Transcripts of (a) two Na+ channel α-subunit genes (SCN5A and SCN6A), (b) six Ca2+ channel α–subunit genes (α1A, α1B, α1X, α1D, α1Eand α1G) and many regulatory subunits (α2δ1, β1-4, and γ6), (c) 22 Kv channel α–subunit genes (Kv1.1 - Kv1.7, Kv1.10, Kv2.1, Kv3.1, Kv3.3, Kv3.4, Kv4.1, Kv4.2, Kv5.1, Kv 6.1-Kv6.3, Kv9.1, Kv9.3, Kv10.1 and Kv11.1) and three Kv channel β-subunit genes (Kvβ1-3) and (d) four Kca channel α–subunit genes (Sloα1 and SK2-SK4) and four Kca channel β-subunit genes (Kcaβ1-4) have been detected in PASMC. Tetrodotoxin-sensitive and rapidly inactivating Na+ currents have been recorded with properties similar to those in cardiac myocytes. In the presence of 20 mM external Ca2+, membrane depolarization from a holding potential of -100 mV elicits a rapidly inactivating T-type Ca2+ current, while depolarization from a holding potential of -70 mV elicits a slowly inactivating dihydropyridine-sensitive L-type Ca2+ current. This review will focus on describing the electrophysiological properties and molecular identities of these voltage-dependent cation channels in PASMC and their contribution to the regulation of pulmonary vascular function and its potential role in the pathogenesis of pulmonary vascular disease.
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Affiliation(s)
- Amy L Firth
- The Salk Institute for Biological Studies, La Jolla, California, USA
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Salomonsson M, Braunstein TH, Holstein-Rathlou NH, Jensen LJ. Na+-independent, nifedipine-resistant rat afferent arteriolar Ca2+ responses to noradrenaline: possible role of TRPC channels. Acta Physiol (Oxf) 2010; 200:265-78. [PMID: 20426773 DOI: 10.1111/j.1748-1716.2010.02141.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIM In rat afferent arterioles we investigated the role of Na(+) entry in noradrenaline (NA)-induced depolarization and voltage-dependent Ca(2+) entry together with the importance of the transient receptor potential channel (TRPC) subfamily for non-voltage-dependent Ca(2+) entry. METHODS R (340/380) Fura-2 fluorescence was used as an index for intracellular free Ca(2+) concentration ([Ca(2+)](i)). Immunofluorescence detected the expression of TRPC channels. RESULTS TRPC 1, 3 and 6 were expressed in afferent arteriolar vascular smooth muscle cells. Under extracellular Na(+)-free (0 Na) conditions, the plateau response to NA was 115% of the baseline R(340/380) (control response 123%). However, as the R(340/380) baseline increased (7%) after 0 Na the plateau reached the same level as during control conditions. Similar responses were obtained after blockade of the Na(+)/Ca(2+) exchanger. The L-type blocker nifedipine reduced the plateau response to NA both under control (from 134% to 116% of baseline) and 0 Na conditions (from 112% to 103% of baseline). In the presence of nifedipine, the putative TRPC channel blockers SKF 96365 (30 μm) and Gd(3+) (100 μm) further reduced the plateau Ca(2+) responses to NA (from 117% to 102% and from 117% to 110% respectively). CONCLUSION We found that Na(+) is not crucial for the NA-induced depolarization that mediates Ca(2+) entry via L-type channels. In addition, the results are consistent with the idea that TRPC1/3/6 Ca(2+) -permeable cation channels expressed in afferent arteriolar smooth muscle cells mediate Ca(2+) entry during NA stimulation.
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Affiliation(s)
- M Salomonsson
- Division of Renal and Vascular Research, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Bocquet A, Sablayrolles S, Vacher B, Le Grand B. F 15845, a new blocker of the persistent sodium current prevents consequences of hypoxia in rat femoral artery. Br J Pharmacol 2010; 161:405-15. [PMID: 20735424 PMCID: PMC2989591 DOI: 10.1111/j.1476-5381.2010.00912.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 03/18/2010] [Accepted: 04/14/2010] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE The persistent sodium current is involved in myocardial ischaemia and is selectively inhibited by the newly described 3-(R)-[3-(2-methoxyphenylthio-2-(S)-methylpropyl]amino-3,4-dihydro-2H-1,5-benzoxathiepine bromhydrate (F 15845). Here, we describe the pharmacological profile of F 15845 against the effects of hypoxia in femoral arteries in vitro. EXPERIMENTAL APPROACH Isometric tension measurement of rat isolated femoral arteries was used to characterize the protective effect of F 15845 against contraction of the vessels induced by veratrine (100 microg.mL(-1)) or hypoxia. KEY RESULTS Rat femoral artery expressed the Na(v)1.5 channel isoform. When exposed to veratrine (100 microg.mL(-1)), vessels developed a rapid and strong contraction that was abolished by both absence of sodium and blockade of the Na(+)/Ca(++) exchanger by KB-R7943 (10 and 32 micromol.L(-1)) or treatment with F 15845. When used before veratrine exposure, the potency of F 15845 depended on the extracellular K(+) concentration (IC(50)= 11 and 0.77 micromol.L(-1) for 5 and 20 mmol.L(-1) KCl, respectively), whereas its potency was unaffected by extracellular K(+) concentration when given after veratrine. F 15845 did not affect either KCl (80 mmol.L(-1)) or phenylephrine-induced femoral artery contraction. Moreover, endothelium disruption did not affect the protective effect of F 15845 against veratrine-induced femoral artery contraction, suggesting a mechanism of action dependent on smooth muscle cells. Finally, F 15845 prevented in a concentration-dependent manner rat femoral artery contraction induced by hypoxia. CONCLUSION AND IMPLICATIONS F 15845, a selective blocker of the persistent sodium current prevented vascular contraction induced by hypoxic conditions.
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Affiliation(s)
- A Bocquet
- Centre de Recherche Pierre Fabre, Castres cedex, France
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20
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Extracellular calcium depletion transiently elevates oxygen consumption in neurosecretory PC12 cells through activation of mitochondrial Na+/Ca2+ exchange. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1627-37. [DOI: 10.1016/j.bbabio.2010.06.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Revised: 05/31/2010] [Accepted: 06/09/2010] [Indexed: 11/18/2022]
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21
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Zulian A, Baryshnikov SG, Linde CI, Hamlyn JM, Ferrari P, Golovina VA. Upregulation of Na+/Ca2+ exchanger and TRPC6 contributes to abnormal Ca2+ homeostasis in arterial smooth muscle cells from Milan hypertensive rats. Am J Physiol Heart Circ Physiol 2010; 299:H624-33. [PMID: 20622104 DOI: 10.1152/ajpheart.00356.2010] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Milan hypertensive strain (MHS) of rats is a model for hypertension in humans. Inherited defects in renal function have been well studied in MHS rats, but the mechanisms that underlie the elevated vascular resistance are unclear. Altered Ca(2+) signaling plays a key role in the vascular dysfunction associated with arterial hypertension. Here we compared Ca(2+) signaling in mesenteric artery smooth muscle cells from MHS rats and its normotensive counterpart (MNS). Systolic blood pressure was higher in MHS than in MNS rats (144 +/- 2 vs. 113 +/- 1 mmHg, P < 0.05). Resting cytosolic free Ca(2+) concentration (measured with fura-2) and ATP-induced Ca(2+) transients were augmented in freshly dissociated arterial myocytes from MHS rats. Ba(2+) entry activated by the diacylglycerol analog 1-oleoyl-2-acetyl-sn-glycerol (a measure of receptor-operated channel activity) was much greater in MHS than MNS arterial myocytes. This correlated with a threefold upregulation of transient receptor potential canonical 6 (TRPC6) protein. TRPC3, the other component of receptor-operated channels, was marginally, but not significantly, upregulated. The expression of TRPC1/5, components of store-operated channels, was not altered in MHS mesenteric artery smooth muscle. Immunoblots also revealed that the Na(+)/Ca(2+) exchanger-1 (NCX1) was greatly upregulated in MHS mesenteric artery (by approximately 13-fold), whereas the expression of plasma membrane Ca(2+)-ATPase was not altered. Ca(2+) entry via the reverse mode of NCX1 evoked by the removal of extracellular Na(+) induced a rapid increase in cytosolic free Ca(2+) concentration that was significantly larger in MHS arterial myocytes. The expression of alpha(1)/alpha(2) Na(+) pumps in MHS mesenteric arteries was not changed. Immunocytochemical observations showed that NCX1 and TRPC6 are clustered in plasma membrane microdomains adjacent to the underlying sarcoplasmic reticulum. In summary, MHS arteries exhibit upregulated TRPC6 and NCX1 and augmented Ca(2+) signaling. We suggest that the increased Ca(2+) signaling contributes to the enhanced vasoconstriction and elevated blood pressure in MHS rats.
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Affiliation(s)
- Alessandra Zulian
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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22
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Giachini FR, Tostes RC. Does Na+ really play a role in Ca2+ homeostasis in hypertension? Am J Physiol Heart Circ Physiol 2010; 299:H602-4. [PMID: 20543080 DOI: 10.1152/ajpheart.00542.2010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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23
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Pojoga LH, Adamová Z, Kumar A, Stennett AK, Romero JR, Adler GK, Williams GH, Khalil RA. Sensitivity of NOS-dependent vascular relaxation pathway to mineralocorticoid receptor blockade in caveolin-1-deficient mice. Am J Physiol Heart Circ Physiol 2010; 298:H1776-88. [PMID: 20363891 DOI: 10.1152/ajpheart.00661.2009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Endothelial caveolin-1 (cav-1) is an anchoring protein in plasma membrane caveolae where it binds endothelial nitric oxide synthase (eNOS) and limits its activation, particularly in animals fed a high salt (HS) diet. Cav-1 also interacts with steroid receptors such as the mineralocorticoid receptor (MR). To test the hypothesis that vascular reactivity is influenced by an interplay between MR and cav-1 during HS diet, we examined the effects of MR blockade on NOS-mediated vascular relaxation in normal and cav-1-deficient mice. Wild-type (WT) and cav-1 knockout mice (cav-1(-/-)) were fed for 14 days a HS (4% NaCl) diet with and without the MR antagonist eplerenone (Epl; 100 mg x kg(-1) x day(-1)). After systolic blood pressure (BP) was measured, the thoracic aorta was isolated for measurement of vascular reactivity, and the aorta and heart were used for measurement of eNOS and MR expression. BP was not different between WT + Epl and WT, but was higher in cav-1(-/-) + Epl than in cav-1(-/-) mice. Phenylephrine (Phe)-induced vascular contraction was less in cav-1(-/-) than WT, and significantly enhanced in cav-1(-/-) + Epl than in cav-1(-/-), but not in WT + Epl compared with WT. Endothelium removal and NOS blockade by N(omega)-nitro-l-arginine methyl ester (l-NAME) enhanced Phe contraction in cav-1(-/-), but not cav-1(-/-) + Epl. ACh-induced aortic relaxation was reduced in cav-1(-/-) + Epl versus cav-1(-/-), but not in WT + Epl compared with WT. Endothelium removal, l-NAME, and the guanylate cyclase inhibitor ODQ abolished the large ACh-induced relaxation in cav-1(-/-) and the remaining relaxation in the cav-1(-/-) + Epl but had similar inhibitory effect in WT and WT + Epl. Real-time RT-PCR indicated decreased eNOS mRNA expression in the aorta and heart, and Western blots revealed decreased total eNOS in the heart of cav-1(-/-) + Epl compared with cav-1(-/-). Vascular and cardiac MR expression was less in cav-1(-/-) than WT, but not in cav-1(-/-) + Epl compared with cav-1(-/-). Plasma aldosterone (Aldo) was not different between WT and cav-1(-/-) mice nontreated or treated with Epl. Thus in cav-1 deficiency states and HS diet MR blockade is associated with increased BP, enhanced vasoconstriction, and decreased NOS-mediated vascular relaxation and eNOS expression. The data suggest that, in the absence of cav-1, MR activation plays a beneficial role in regulating eNOS expression/activity and, consequently, the vascular function during HS diet.
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Affiliation(s)
- Luminita H Pojoga
- Cardiovascular Endocrine Section, Endocrinology, Diabetes and Hypertension Division, Harvard Medical School, Boston, MA, USA
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Signaling mechanisms that link salt retention to hypertension: endogenous ouabain, the Na(+) pump, the Na(+)/Ca(2+) exchanger and TRPC proteins. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1219-29. [PMID: 20211726 DOI: 10.1016/j.bbadis.2010.02.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Revised: 02/26/2010] [Accepted: 02/27/2010] [Indexed: 12/26/2022]
Abstract
Salt retention as a result of chronic, excessive dietary salt intake, is widely accepted as one of the most common causes of hypertension. In a small minority of cases, enhanced Na(+) reabsorption by the kidney can be traced to specific genetic defects of salt transport, or pathological conditions of the kidney, adrenal cortex, or pituitary. Far more frequently, however, salt retention may be the result of minor renal injury or small genetic variation in renal salt transport mechanisms. How salt retention actually leads to the increase in peripheral vascular resistance (the hallmark of hypertension) and the elevation of blood pressure remains an enigma. Here we review the evidence that endogenous ouabain (an adrenocortical hormone), arterial smooth muscle α2 Na(+) pumps, type-1 Na/Ca exchangers, and receptor- and store-operated Ca(2+) channels play key roles in the pathway that links salt to hypertension. We discuss cardenolide structure-function relationships in an effort to understand why prolonged administration of ouabain, but not digoxin, induces hypertension, and why digoxin is actually anti-hypertensive. Finally, we summarize recent observations which indicate that ouabain upregulates arterial myocyte Ca(2+) signaling mechanisms that promote vasoconstriction, while simultaneously downregulating endothelial vasodilator mechanisms. In sum, the reports reviewed here provide novel insight into the molecular mechanisms by which salt retention leads to hypertension.
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25
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Liu J, Xie ZJ. The sodium pump and cardiotonic steroids-induced signal transduction protein kinases and calcium-signaling microdomain in regulation of transporter trafficking. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1237-45. [PMID: 20144708 DOI: 10.1016/j.bbadis.2010.01.013] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 01/28/2010] [Accepted: 01/30/2010] [Indexed: 12/12/2022]
Abstract
The Na/K-ATPase was discovered as an energy transducing ion pump. A major difference between the Na/K-ATPase and other P-type ATPases is its ability to bind a group of chemicals called cardiotonic steroids (CTS). The plant-derived CTS such as digoxin are valuable drugs for the management of cardiac diseases, whereas ouabain and marinobufagenin (MBG) have been identified as a new class of endogenous hormones. Recent studies have demonstrated that the endogenous CTS are important regulators of renal Na(+) excretion and blood pressure. The Na/K-ATPase is not only an ion pump, but also an important receptor that can transduce the ligand-like effect of CTS on intracellular protein kinases and Ca(2+) signaling. Significantly, these CTS-provoked signaling events are capable of reducing the surface expression of apical NHE3 (Na/H exchanger isoform 3) and basolateral Na/K-ATPase in renal proximal tubular cells. These findings suggest that endogenous CTS may play an important role in regulation of tubular Na(+) excretion under physiological conditions; conversely, a defect at either the receptor level (Na/K-ATPase) or receptor-effector coupling would reduce the ability of renal proximal tubular cells to excrete Na(+), thus culminating/resulting in salt-sensitive hypertension.
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Affiliation(s)
- Jiang Liu
- Department of Medicine, University of Toledo College of Medicine, Toledo, OH, USA
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26
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Pulina MV, Zulian A, Berra-Romani R, Beskina O, Mazzocco-Spezzia A, Baryshnikov SG, Papparella I, Hamlyn JM, Blaustein MP, Golovina VA. Upregulation of Na+ and Ca2+ transporters in arterial smooth muscle from ouabain-induced hypertensive rats. Am J Physiol Heart Circ Physiol 2009; 298:H263-74. [PMID: 19897708 DOI: 10.1152/ajpheart.00784.2009] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Prolonged ouabain administration (25 microg kg(-1) day(-1) for 5 wk) induces "ouabain hypertension" (OH) in rats, but the molecular mechanisms by which ouabain elevates blood pressure are unknown. Here, we compared Ca(2+) signaling in mesenteric artery smooth muscle cells (ASMCs) from normotensive (NT) and OH rats. Resting cytosolic free Ca(2+) concentration ([Ca(2+)](cyt); measured with fura-2) and phenylephrine-induced Ca(2+) transients were augmented in freshly dissociated OH ASMCs. Immunoblots revealed that the expression of the ouabain-sensitive alpha(2)-subunit of Na(+) pumps, but not the predominant, ouabain-resistant alpha(1)-subunit, was increased (2.5-fold vs. NT ASMCs) as was Na(+)/Ca(2+) exchanger-1 (NCX1; 6-fold vs. NT) in OH arteries. Ca(2+) entry, activated by sarcoplasmic reticulum (SR) Ca(2+) store depletion with cyclopiazonic acid (SR Ca(2+)-ATPase inhibitor) or caffeine, was augmented in OH ASMCs. This reflected an augmented expression of 2.5-fold in OH ASMCs of C-type transient receptor potential TRPC1, an essential component of store-operated channels (SOCs); two other components of some SOCs were not expressed (TRPC4) or were not upregulated (TRPC5). Ba(2+) entry activated by the diacylglycerol analog 1-oleoyl-2-acetyl-sn-glycerol [a measure of receptor-operated channel (ROC) activity] was much greater in OH than NT ASMCs. This correlated with a sixfold upregulation of TRPC6 protein, a ROC family member. Importantly, in primary cultured mesenteric ASMCs from normal rats, 72-h treatment with 100 nM ouabain significantly augmented NCX1 and TRPC6 protein expression and increased resting [Ca(2+)](cyt) and ROC activity. SOC activity was also increased. Silencer RNA knockdown of NCX1 markedly downregulated TRPC6 and eliminated the ouabain-induced augmentation; silencer RNA knockdown of TRPC6 did not affect NCX1 expression but greatly attenuated its upregulation by ouabain. Clearly, NCX1 and TRPC6 expression are interrelated. Thus, prolonged ouabain treatment upregulates the Na(+) pump alpha(2)-subunit-NCX1-TRPC6 (ROC) Ca(2+) signaling pathway in arterial myocytes in vitro as well as in vivo. This may explain the augmented myogenic responses and enhanced phenylephrine-induced vasoconstriction in OH arteries (83) as well as the high blood pressure in OH rats.
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Affiliation(s)
- Maria V Pulina
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA
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Romero-Méndez C, Algara-Suárez P, Sánchez-Armass S, Mandeville PB, Meza U, Espinosa-Tanguma R. ROLE OF EXTRACELLULAR Na+, Ca2+-ACTIVATED Cl-CHANNELS AND BK CHANNELS IN THE CONTRACTION OF Ca2+STORE-DEPLETED TRACHEAL SMOOTH MUSCLE. Clin Exp Pharmacol Physiol 2009; 36:619-25. [DOI: 10.1111/j.1440-1681.2008.05115.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Syyong HT, Yang HHC, Trinh G, Cheung C, Kuo KH, van Breemen C. Mechanism of asynchronous Ca(2+) waves underlying agonist-induced contraction in the rat basilar artery. Br J Pharmacol 2009; 156:587-600. [PMID: 19154440 DOI: 10.1111/j.1476-5381.2008.00063.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND AND PURPOSE Uridine 5'-triphosphate (UTP) is a potent vasoconstrictor of cerebral arteries and induces Ca(2+) waves in vascular smooth muscle cells (VSMCs). This study aimed to determine the mechanisms underlying UTP-induced Ca(2+) waves in VSMCs of the rat basilar artery. EXPERIMENTAL APPROACH Isometric force and intracellular Ca(2+) ([Ca(2+)](i)) were measured in endothelium-denuded rat basilar artery using wire myography and confocal microscopy respectively. KEY RESULTS Uridine 5'-triphosphate (0.1-1000 micromol.L(-1)) concentration-dependently induced tonic contraction (pEC(50) = 4.34 +/- 0.13), associated with sustained repetitive oscillations in [Ca(2+)](i) propagating along the length of the VSMCs as asynchronized Ca(2+) waves. Inhibition of Ca(2+) reuptake in sarcoplasmic reticulum (SR) by cyclopiazonic acid abolished the Ca(2+) waves and resulted in a dramatic drop in tonic contraction. Nifedipine reduced the frequency of Ca(2+) waves by 40% and tonic contraction by 52%, and the nifedipine-insensitive component was abolished by SKF-96365, an inhibitor of receptor- and store-operated channels, and KB-R7943, an inhibitor of reverse-mode Na(+)/Ca(2+) exchange. Ongoing Ca(2+) waves and tonic contraction were also abolished after blockade of inositol-1,4,5-triphosphate-sensitive receptors by 2-aminoethoxydiphenylborate, but not by high concentrations of ryanodine or tetracaine. However, depletion of ryanodine-sensitive SR Ca(2+) stores prior to UTP stimulation prevented Ca(2+) waves. CONCLUSIONS AND IMPLICATIONS Uridine 5'-triphosphate-induced Ca(2+) waves may underlie tonic contraction and appear to be produced by repetitive cycles of regenerative Ca(2+) release from the SR through inositol-1,4,5-triphosphate-sensitive receptors. Maintenance of Ca(2+) waves requires SR Ca(2+) reuptake from Ca(2+) entry across the plasma membrane via L-type Ca(2+) channels, receptor- and store-operated channels, and reverse-mode Na(+)/Ca(2+) exchange.
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Affiliation(s)
- H T Syyong
- Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada
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Kashihara T, Nakayama K, Matsuda T, Baba A, Ishikawa T. Role of Na+/Ca2+ Exchanger–Mediated Ca2+ Entry in Pressure-Induced Myogenic Constriction in Rat Posterior Cerebral Arteries. J Pharmacol Sci 2009; 110:218-22. [DOI: 10.1254/jphs.09054sc] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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30
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Poburko D, Liao CH, van Breemen C, Demaurex N. Mitochondrial regulation of sarcoplasmic reticulum Ca2+ content in vascular smooth muscle cells. Circ Res 2008; 104:104-12. [PMID: 19023135 DOI: 10.1161/circresaha.108.180612] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Subplasmalemmal ion fluxes have global effects on Ca(2+) signaling in vascular smooth muscle. Measuring cytoplasmic and mitochondrial [Ca(2+)]and [Na(+)], we previously showed that mitochondria buffer both subplasmalemmal cytosolic [Ca(2+)] and [Na(+)] in vascular smooth muscle cells. We have now directly measured sarcoplasmic reticulum [Ca(2+)] in aortic smooth muscle cells, revealing that mitochondrial Na(+)/Ca(2+) exchanger inhibition with CGP-37157 impairs sarcoplasmic reticulum Ca(2+) refilling during purinergic stimulation. By overexpressing hFis1 to remove mitochondria from the subplasmalemmal space, we show that the rate and extent of sarcoplasmic reticulum refilling is augmented by a subpopulation of peripheral mitochondria. In ATP-stimulated cells, hFis-1-mediated relocalization of mitochondria impaired the sarcoplasmic reticulum refilling process and reduced mitochondrial [Ca(2+)] elevations, despite increased cytosolic [Ca(2+)] elevations. Reversal of plasmalemmal Na(+)/Ca(2+) exchange was the primary Ca(2+) entry mechanism following ATP stimulation, based on the effects of KB-R7943. We propose that subplasmalemmal mitochondria ensure efficient sarcoplasmic reticulum refilling by cooperating with the plasmalemmal Na(+)/Ca(2+) exchanger to funnel Ca(2+) into the sarcoplasmic reticulum and minimize cytosolic [Ca(2+)] elevations that might otherwise contribute to hypertensive or proliferative vasculopathies.
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Affiliation(s)
- Damon Poburko
- Department of Cell Physiology and Metabolism, University of Geneva, 1 Michel-Servet, CH-1211 Geneva 4, Switzerland.
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31
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Cao C, Payne K, Lee-Kwon W, Zhang Z, Lim SW, Hamlyn J, Blaustein MP, Kwon HM, Pallone TL. Chronic ouabain treatment induces vasa recta endothelial dysfunction in the rat. Am J Physiol Renal Physiol 2008; 296:F98-F106. [PMID: 18945826 DOI: 10.1152/ajprenal.90429.2008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Descending vasa recta (DVR) are 15-microm vessels that perfuse the renal medulla. Ouabain has been shown to augment DVR endothelial cytoplasmic Ca(2+) ([Ca(2+)](CYT)) signaling. In this study, we examined the expression of the ouabain-sensitive Na-K-ATPase alpha2 subunit in the rat renal vasculature and tested effects of acute ouabain exposure and chronic ouabain treatment on DVR. Immunostaining with antibodies directed against the alpha2 subunit verified its expression in both DVR pericytes and endothelium. Acute application of ouabain (100 or 500 nM) augmented the DVR nitric oxide generation stimulated by acetylcholine (ACh; 10 microM). At a concentration of 1 mM, ouabain constricted microperfused DVR, whereas at 100 nM, it was without effect. Acute ouabain (100 nM) did not augment constriction by angiotensin II (0.5 or 10 nM), whereas l-nitroarginine methyl ester-induced contraction of DVR was slightly enhanced. Ouabain-hypertensive (OH) rats were generated by chronic ouabain treatment (30 microg.kg(-1).day(-1), 5 wk). The acute endothelial [Ca(2+)](CYT) elevation by ouabain (100 nM) was absent in DVR endothelia of OH rats. The [Ca(2+)](CYT) response to 10 nM ACh was also eliminated, whereas the response to 10 microM ACh was not. The endothelial [Ca(2+)](CYT) response to bradykinin (100 nM) was significantly attenuated. We conclude that endothelial responses may offset the ability of acute ouabain exposure to enhance DVR vasoconstriction. Chronic exposure to ouabain, in vivo, leads to hypertension and DVR endothelial dysfunction, manifested as reduced [Ca(2+)](CYT) responses to both ouabain- and endothelium-dependent vasodilators.
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Affiliation(s)
- Chunhua Cao
- Department of Medicine, UMMS, Baltimore, MD 21201, USA
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32
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Kapela A, Bezerianos A, Tsoukias NM. A mathematical model of Ca2+ dynamics in rat mesenteric smooth muscle cell: agonist and NO stimulation. J Theor Biol 2008; 253:238-60. [PMID: 18423672 DOI: 10.1016/j.jtbi.2008.03.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 02/28/2008] [Accepted: 03/03/2008] [Indexed: 11/27/2022]
Abstract
A mathematical model of calcium dynamics in vascular smooth muscle cell (SMC) was developed based on data mostly from rat mesenteric arterioles. The model focuses on (a) the plasma membrane electrophysiology; (b) Ca2+ uptake and release from the sarcoplasmic reticulum (SR); (c) cytosolic balance of Ca2+, Na+, K+, and Cl ions; and (d) IP3 and cGMP formation in response to norepinephrine(NE) and nitric oxide (NO) stimulation. Stimulation with NE induced membrane depolarization and an intracellular Ca2+ ([Ca2+]i) transient followed by a plateau. The plateau concentrations were mostly determined by the activation of voltage-operated Ca2+ channels. NE causes a greater increase in [Ca2+]i than stimulation with KCl to equivalent depolarization. Model simulations suggest that the effect of[Na+]i accumulation on the Na+/Ca2+ exchanger (NCX) can potentially account for this difference.Elevation of [Ca2+]i within a concentration window (150-300 nM) by NE or KCl initiated [Ca2+]i oscillations with a concentration-dependent period. The oscillations were generated by the nonlinear dynamics of Ca2+ release and refilling in the SR. NO repolarized the NE-stimulated SMC and restored low [Ca2+]i mainly through its effect on Ca2+-activated K+ channels. Under certain conditions, Na+-K+-ATPase inhibition can result in the elevation of [Na+]i and the reversal of NCX, increasing resting cytosolic and SR Ca2+ content, as well as reactivity to NE. Blockade of the NCX's reverse mode could eliminate these effects. We conclude that the integration of the selected cellular components yields a mathematical model that reproduces, satisfactorily, some of the established features of SMC physiology. Simulations suggest a potential role of intracellular Na+ in modulating Ca2+ dynamics and provide insights into the mechanisms of SMC constriction, relaxation, and the phenomenon of vasomotion. The model will provide the basis for the development of multi-cellular mathematical models that will investigate microcirculatory function in health and disease.
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MESH Headings
- Animals
- Calcium/metabolism
- Calcium Channels/physiology
- Membrane Potentials/physiology
- Mesentery/blood supply
- Microcirculation/drug effects
- Microcirculation/physiology
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Nitric Oxide/pharmacology
- Potassium Channels, Calcium-Activated/physiology
- Potassium Channels, Voltage-Gated/physiology
- Proteins/pharmacology
- Rats
- Ryanodine Receptor Calcium Release Channel/metabolism
- Sarcoplasmic Reticulum/metabolism
- ATPase Inhibitory Protein
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Affiliation(s)
- Adam Kapela
- Department of Biomedical Engineering, Florida International University, Miami, FL 33199, USA.
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33
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Raina H, Ella SR, Hill MA. Decreased activity of the smooth muscle Na+/Ca2+ exchanger impairs arteriolar myogenic reactivity. J Physiol 2008; 586:1669-81. [PMID: 18218677 DOI: 10.1113/jphysiol.2007.150268] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Arteriolar myogenic vasoconstriction occurs when stretch or increased membrane tension leads to smooth muscle cell (SMC) depolarization and opening of voltage-gated Ca(2+) channels. While the mechanism underlying the depolarization is uncertain a role for non-selective cation channels has been demonstrated. As such channels may be expected to pass Na(+), we hypothesized that reverse mode Na(+)/Ca(2+) exchange (NCX) may act to remove Na(+) and in addition play a role in myogenic signalling through coupled Ca(2+) entry. Further, reverse (Ca(2+) entry) mode function of the NCX is favoured by the membrane potential found in myogenically active arterioles. All experiments were performed on isolated rat cremaster muscle first order arterioles (passive diameter approximately 150 mum) which were pressurized in the absence of intraluminal flow. Reduction of extracellular Na(+) to promote reverse-mode NCX activity caused significant, concentration-dependent vasoconstriction and increased intracellular Ca(2+). This vasoconstriction was attenuated by the NCX inhibitors KB-R7943 and SEA 04000. Western blotting confirmed the existence of NCX protein while real-time PCR studies demonstrated that the major isoform expressed in the arteriolar wall was NCX1. Oligonucleotide knockdown (24 and 36 h) of NCX inhibited the vasoconstrictor response to reduced extracellular Na(+) while also impairing both steady-state myogenic responses (as shown by pressure-diameter relationships) and acute reactivity to a 50 to 120 mmHg pressure step. The data are consistent with reverse mode activity of the NCX in arterioles and a contribution of this exchanger to myogenic vasoconstriction.
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Affiliation(s)
- Hema Raina
- School of Medical Sciences, RMIT University, Bundoora, Victoria 3083, Australia
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34
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Raizman JE, Komljenovic J, Chang R, Deng C, Bedosky KM, Rattan SG, Cunnington RH, Freed DH, Dixon IMC. The participation of the Na+-Ca2+ exchanger in primary cardiac myofibroblast migration, contraction, and proliferation. J Cell Physiol 2008; 213:540-51. [PMID: 17541957 DOI: 10.1002/jcp.21134] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Cardiac ventricular myofibroblast motility, proliferation, and contraction contribute to post-myocardial infarct wound healing, infarct scar formation, and remodeling of the ventricle remote to the site of infarction. The Na+-Ca2+ exchanger (NCX1) is involved in altered calcium handling in cardiac myocytes during cardiac remodeling associated with heart failure, however, its role in cardiac myofibroblast cell function is unexplored. In this study we investigated the involvement of NCX1 as well as the role of non-selective-cation channels (NSCC) in cardiac myofibroblast cell function in vitro. Immunofluorescence and Western blots revealed that P1 cells upregulate alpha-smooth muscle actin (alphaSMA) and embryonic smooth muscle myosin heavy chain (SMemb) expression. NCX1 mRNA and proteins as well as Ca(v)1.2a protein are also expressed in P1 myofibroblasts. Myofibroblast motility in the presence of 50 ng/ml PDGF-BB was blocked with AG1296. Myofibroblast motility, contraction, and proliferation were sensitive to KB-R7943, a specific NCX1 reverse-mode inhibitor. In contrast, only proliferation and contraction, but not motility were sensitive to nifedipine, while gadolinium (NSCC blocker) was only associated with decreased motility. ML-7 treatment was associated with inhibition of the chemotactic response and contraction. Thus cardiac myofibroblast chemotaxis, contraction, and proliferation were sensitive to different pharmacologic treatments suggesting that regulation of transplasmalemmal calcium movements may be important in growth factor receptor-mediated processes. NCX1 may represent an important moiety in suppression of myofibroblast functions.
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Affiliation(s)
- Joshua E Raizman
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre and Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada
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35
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Kansui Y, Garland CJ, Dora KA. Enhanced spontaneous Ca2+ events in endothelial cells reflect signalling through myoendothelial gap junctions in pressurized mesenteric arteries. Cell Calcium 2008; 44:135-46. [PMID: 18191200 DOI: 10.1016/j.ceca.2007.11.012] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Revised: 11/01/2007] [Accepted: 11/05/2007] [Indexed: 11/15/2022]
Abstract
Increases in global Ca(2+) in the endothelium are a crucial step in releasing relaxing factors to modulate arterial tone. In the present study we investigated spontaneous Ca(2+) events in endothelial cells, and the contribution of smooth muscle cells to these Ca(2+) events, in pressurized rat mesenteric resistance arteries. Spontaneous Ca(2+) events were observed under resting conditions in 34% of cells. These Ca(2+) events were absent in arteries preincubated with either cyclopiazonic acid or U-73122, but were unaffected by ryanodine or nicotinamide. Stimulation of smooth muscle cell depolarization and contraction with either phenylephrine or high concentrations of KCl significantly increased the frequency of endothelial cell Ca(2+) events. The putative gap junction uncouplers carbenoxolone and 18alpha-glycyrrhetinic acid each inhibited spontaneous and evoked Ca(2+) events, and the movement of calcein from endothelial to smooth muscle cells. In addition, spontaneous Ca(2+) events were diminished by nifedipine, lowering extracellular Ca(2+) levels, or by blockers of non-selective Ca(2+) influx pathways. These findings suggest that in pressurized rat mesenteric arteries, spontaneous Ca(2+) events in the endothelial cells appear to originate from endoplasmic reticulum IP(3) receptors, and are subject to regulation by surrounding smooth muscle cells via myoendothelial gap junctions, even under basal conditions.
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Affiliation(s)
- Yasuo Kansui
- Department of Pharmacy and Pharmacology, University of Bath, Bath BA 7AY, UK
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36
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Zhang Q, Cao C, Zhang Z, Wier WG, Edwards A, Pallone TL. Membrane current oscillations in descending vasa recta pericytes. Am J Physiol Renal Physiol 2008; 294:F656-66. [PMID: 18184740 DOI: 10.1152/ajprenal.00493.2007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the origin of spontaneous transient inward current (STIC) oscillations in descending vasa recta (DVR) pericytes. In cells clamped at -80 mV, angiotensin II (ANG II; 10 nmol/l) induced oscillations with mean amplitude and frequency of -65.5 pA and 1.2 Hz. Simultaneous recording of cytoplasmic calcium ([Ca(2+)](CYT)) and membrane current oscillations verified their synchrony and the correlation of their amplitudes. Confocal recording in fluo-4-loaded DVR showed that ANG II can induce either stable pericyte [Ca(2+)](CYT) elevation or oscillations, while decreasing adjacent endothelial [Ca(2+)](CYT). Oscillating currents reversed sign at -30.2 mV and were blocked by niflumic acid, implicating charge transfer via Cl(-) ion. Removal of extracellular Ca(2+), blockade of Ca(2+) influx with SKF96365 (30 micromol/l), ryanodine (30 micromol/l), or caffeine (10 mmol/l) inhibited oscillations. In contrast, they were insensitive to removal of extracellular Na(+) and exposure to either nifedipine (1 micromol/l) or 2-aminoethoxydiphenyl borate (10 micromol/l). Ouabain (100 nmol/l) increased basal pericyte [Ca(2+)](CYT) and the frequency of resting STICs but did not affect the larger oscillations that followed ANG II stimulation. We conclude that [Ca(2+)](CYT) oscillations stimulate Cl(-) currents. The former are most likely maintained by repetitive cycles of ryanodine-sensitive SR Ca(2+) release and SKF96365-sensitive store refilling.
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Affiliation(s)
- Qingli Zhang
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
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37
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Pojoga LH, Yao TM, Sinha S, Ross RL, Lin JC, Raffetto JD, Adler GK, Williams GH, Khalil RA. Effect of dietary sodium on vasoconstriction and eNOS-mediated vascular relaxation in caveolin-1-deficient mice. Am J Physiol Heart Circ Physiol 2008; 294:H1258-65. [PMID: 18178722 DOI: 10.1152/ajpheart.01014.2007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Changes in dietary sodium intake are associated with changes in vascular volume and reactivity that may be mediated, in part, by alterations in endothelial nitric oxide synthase (eNOS) activity. Caveolin-1 (Cav-1), a transmembrane anchoring protein in the plasma membrane caveolae, binds eNOS and limits its translocation and activation. To test the hypothesis that endothelial Cav-1 participates in the dietary sodium-mediated effects on vascular function, we assessed vascular responses and nitric oxide (NO)-mediated mechanisms of vascular relaxation in Cav-1 knockout mice (Cav-1-/-) and wild-type control mice (WT; Cav-1+/+) placed on a high-salt (HS; 4% NaCl) or low-salt (LS; 0.08% NaCl) diet for 16 days. After the systolic blood pressure was measured, the thoracic aorta was isolated for measurement of vascular reactivity and NO production, and the heart was used for measurement of eNOS expression and/or activity. The blood pressure was elevated in HS mice treated with NG-nitro-l-arginine methyl ester and more so in Cav-1-/- than WT mice and was significantly reduced during the LS diet. Phenylephrine caused vascular contraction that was significantly reduced in Cav-1-/- (maximum 0.25 +/- 0.06 g/mg) compared with WT (0.75 +/- 0.22 g/mg) on the HS diet, and the differences were eliminated with the LS diet. Also, vascular contraction in response to membrane depolarization by high KCl (96 mM) was reduced in Cav-1-/- (0.27 +/- 0.05 g/mg) compared with WT mice (0.53 +/- 0.12 g/mg) on the HS diet, suggesting that the reduced vascular contraction is not limited to a particular receptor. Acetylcholine (10(-5) M) caused aortic relaxation in WT mice on HS (23.6 +/- 3.5%) and LS (23.7 +/- 5.5%) that was enhanced in Cav-1-/- HS (72.6 +/- 6.1%) and more so in Cav-1-/- LS mice (93.6 +/- 3.5%). RT-PCR analysis indicated increased eNOS mRNA expression in the aorta and heart, and Western blots indicated increased total eNOS and phosphorylated eNOS in the heart of Cav-1-/- compared with WT mice on the HS diet, and the genotypic differences were less apparent during the LS diet. Thus Cav-1 deficiency during the HS diet is associated with decreased vasoconstriction, increased vascular relaxation, and increased eNOS expression and activity, and these effects are altered during the LS diet. The data support the hypothesis that endothelial Cav-1, likely through an effect on eNOS activity, plays a prominent role in the regulation of vascular function during substantial changes in dietary sodium intake.
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Affiliation(s)
- Luminita H Pojoga
- Cardiovascular Endocrine Section, Endocrinology, Diabetes and Hypertension Division, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
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38
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39
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Cai H, Wu L, Qu W, Malhotra D, Xie Z, Shapiro JI, Liu J. Regulation of apical NHE3 trafficking by ouabain-induced activation of the basolateral Na+-K+-ATPase receptor complex. Am J Physiol Cell Physiol 2007; 294:C555-63. [PMID: 18077602 DOI: 10.1152/ajpcell.00475.2007] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The long-term effects of ouabain on transepithelial Na(+) transport involve transcriptional downregulation of apical Na(+)/H(+) exchanger isoform 3 (NHE3). The aim of this study was to determine whether ouabain could acutely regulate NHE3 via a posttranscriptional mechanism in LLC-PK1 cells. We observed that the basolateral, but not apical, application of ouabain for 1 h significantly reduced transepithelial Na(+) transport. This effect was not due to changes in the integrity of tight junctions or increases in the intracellular Na(+) concentration. Ouabain regulated the trafficking of NHE3 and subsequently inhibited its activity, a process independent of intracellular Na(+) concentration. Ouabain-induced NHE3 trafficking was abolished by either cholesterol depletion or Src inhibition. Moreover, ouabain increased the intracellular Ca(2+) concentration. Pretreatment of cells with the intracellular Ca(2+) chelator BAPTA-AM blocked ouabain-induced trafficking of NHE3. Also, blockade of Na(+)-K(+)-ATPase endocytosis by a phosphatidylinositol 3-kinase inhibitor was equally effective in attenuating ouabain-induced NHE3 trafficking. These data indicate that ouabain acutely stimulates NHE3 trafficking by activating the basolateral Na(+)-K(+)-ATPase signaling complex. Taken together with our previous observations, we propose that ouabain can simultaneously regulate basolateral Na(+)-K(+)-ATPase and apical NHE3, leading to inhibition of transepithelial Na(+) transport. This mechanism may be relevant to proximal tubular Na(+) handling during conditions associated with increases in circulating endogenous cardiotonic steroids.
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Affiliation(s)
- Haiping Cai
- Department of Medicine, University of Toledo College of Medicine, 3120 Glendale Ave., Toledo, OH 43614-5089, USA
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40
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Leung FP, Yung LM, Yao X, Laher I, Huang Y. Store-operated calcium entry in vascular smooth muscle. Br J Pharmacol 2007; 153:846-57. [PMID: 17876304 PMCID: PMC2267267 DOI: 10.1038/sj.bjp.0707455] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
In non-excitable cells, activation of G-protein-coupled phospholipase C (PLC)-linked receptors causes the release of Ca(2+) from intracellular stores, which is followed by transmembrane Ca(2+) entry. This Ca(2+) entry underlies a small and sustained phase of the cellular [Ca(2+)](i) increases and is important for several cellular functions including gene expression, secretion and cell proliferation. This form of transmembrane Ca(2+) entry is supported by agonist-activated Ca(2+)-permeable ion channels that are activated by store depletion and is referred to as store-operated Ca(2+) entry (SOCE) and represents a major pathway for agonist-induced Ca(2+) entry. In excitable cells such as smooth muscle cells, Ca(2+) entry mechanisms responsible for sustained cellular activation are normally considered to be mediated via either voltage-operated or receptor-operated Ca(2+) channels. Although SOCE occurs following agonist activation of smooth muscle, this was thought to be more important in replenishing Ca(2+) stores rather than acting as a source of activator Ca(2+) for the contractile process. This review summarizes our current knowledge of SOCE as a regulator of vascular smooth muscle tone and discusses its possible role in the cardiovascular function and disease. We propose a possible hypothesis for its activation and suggest that SOCE may represent a novel target for pharmacological therapeutic intervention.
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Affiliation(s)
- F P Leung
- Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong Hong Kong, China
- Department of Physiology, Chinese University of Hong Kong Hong Kong, China
| | - L M Yung
- Department of Physiology, Chinese University of Hong Kong Hong Kong, China
| | - X Yao
- Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong Hong Kong, China
- Department of Physiology, Chinese University of Hong Kong Hong Kong, China
- Institute of Vascular Medicine, Chinese University of Hong Kong Hong Kong, China
| | - I Laher
- Department of Pharmacology and Therapeutics, University of British Columbia Vancouver, Canada
| | - Y Huang
- Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong Hong Kong, China
- Department of Physiology, Chinese University of Hong Kong Hong Kong, China
- Institute of Vascular Medicine, Chinese University of Hong Kong Hong Kong, China
- Author for correspondence:
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41
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Poburko D, Liao CH, Lemos VS, Lin E, Maruyama Y, Cole WC, van Breemen C. Transient receptor potential channel 6-mediated, localized cytosolic [Na+] transients drive Na+/Ca2+ exchanger-mediated Ca2+ entry in purinergically stimulated aorta smooth muscle cells. Circ Res 2007; 101:1030-8. [PMID: 17872462 DOI: 10.1161/circresaha.107.155531] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Na+/Ca2+ exchanger (NCX) is increasingly recognized as a physiological mediator of Ca2+ influx and significantly contributes to salt-sensitive hypertension. We recently reported that Ca2+ influx by the NCX (1) is the primary mechanism of Ca2+ entry in purinergically stimulated rat aorta smooth muscle cells and (2) requires functional coupling with transient receptor potential channel 6 nonselective cation channels. Using the Na+ indicator CoroNa Green, we now directly observed and characterized the localized cytosolic [Na+] ([Na+]i) elevations that have long been hypothesized to underlie physiological NCX reversal but that have never been directly shown. Stimulation of rat aorta smooth muscle cells caused both global and monotonic [Na+]i elevations and localized [Na+]i transients (LNats) at the cell periphery. Inhibition of nonselective cation channels with SKF-96365 (50 micromol/L) and 2-amino-4-phosphonobutyrate (75 micromol/L) reduced both global and localized [Na+]i elevations in response to ATP (1 mmol/L). This effect was mimicked by expression of a dominant negative construct of transient receptor potential channel 6. Selective inhibition of NCX-mediated Ca2+ entry with KB-R7943 (10 micromol/L) enhanced the LNats, whereas the global cytosolic [Na+] signal was unaffected. Inhibition of mitochondrial Na+ uptake with CGP-37157 (10 micromol/L) increased both LNats and global cytosolic [Na+] elevations. These findings directly demonstrate NCX regulation by LNats, which are restricted to subsarcolemmal, cytoplasmic microdomains. Analysis of the LNats, which facilitate Ca2+ entry via NCX, suggests that mitochondria limit the cytosolic diffusion of LNats generated by agonist-mediated activation of transient receptor potential channel 6-containing channels.
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Affiliation(s)
- Damon Poburko
- Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, Canada, V6T 1Z1
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Clyman RI, Waleh N, Kajino H, Roman C, Mauray F. Calcium-dependent and calcium-sensitizing pathways in the mature and immature ductus arteriosus. Am J Physiol Regul Integr Comp Physiol 2007; 293:R1650-6. [PMID: 17652360 DOI: 10.1152/ajpregu.00300.2007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Studies performed in sheep and baboons have shown that after birth, the normoxic muscle media of ductus arteriosus (DA) becomes profoundly hypoxic as it constricts and undergoes anatomic remodeling. We used isolated fetal lamb DA (pretreated with inhibitors of prostaglandin and nitric oxide production) to determine why the immature DA fails to remain tightly constricted during the hypoxic phase of remodeling. Under normoxic conditions, mature DA constricts to 70% of its maximal active tension (MAT). Half of its normoxic tension is due to Ca(2+) entry through calcium L-channels and store-operated calcium (SOC) channels. The other half is independent of extracellular Ca(2+) and is unaffected by inhibitors of sarcoplasmic reticulum (SR) Ca(2+) release (ryanodine) or reuptake [cyclopiazonic acid (CPA)]. The mature DA relaxes slightly during hypoxia (to 60% MAT) due to decreases in calcium L-channel-mediated Ca(2+) entry. Inhibitors of Rho kinase and tyrosine kinase inhibit both Ca(2+)-dependent and Ca(2+)-independent DA tension. Although Rho kinase activity may increase during gestation, immature DA develop lower tensions than mature DA, primarily because of differences in the way they process Ca(2+). Calcium L-channel expression increases with advancing gestation. Under normoxic conditions, differences in calcium L-channel-mediated Ca(2+) entry account for differences in tension between immature (60% MAT) and mature (70% MAT) DA. Under hypoxic conditions, differences in both calcium L-channel-dependent and calcium L-channel-independent Ca(2+) entry, account for differences in tension between immature (33% MAT) and mature (60% MAT) DA. Stimulation of Ca(2+) entry through reverse-mode Na(+)/Ca(2+) exchange or CPA-induced SOC channel activity constrict the DA and eliminate differences between immature and mature DA during both hypoxia and normoxia.
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Affiliation(s)
- Ronald I Clyman
- Cardiovascular Research Institute and Department of Pediatrics, University of California, San Francisco, 513 Parnassus Ave., Rm. 1408 HSW, UCSF Box 0544, San Francisco, CA 94143-0544, USA.
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Becker S, Moir LM, Snetkov VA, Aaronson PI. Hypoxic pulmonary vasoconstriction in intact rat intrapulmonary arteries is not initiated by inhibition of Na+-Ca2+ exchange. Am J Physiol Lung Cell Mol Physiol 2007; 293:L982-90. [PMID: 17616643 DOI: 10.1152/ajplung.00361.2006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It has been proposed that a hypoxia-induced inhibition of the Na(+)-Ca(2+) exchanger (NCX) contributes to hypoxic pulmonary vasoconstriction (HPV). By recording isometric tension development in rat intrapulmonary arteries (IPA), we examined the effect on HPV of maneuvers that reduce the ability of NCX to regulate intracellular Ca(2+) concentration ([Ca(2+)](i)). In some experiments, fura pentakis(acetoxymethyl) ester-3 (fura PE-3) was also used to monitor [Ca(2+)](i). HPV was elicited in IPA that were pretreated with 10 microM diltiazem and slightly preconstricted with PGF(2alpha), which enhances the hypoxic response. Substitution of Na(+) with Li(+) increased HPV and the associated rise in [Ca(2+)](i). Pretreatment with ouabain (100 microM) to diminish the Na(+) gradient or with the reverse-mode NCX inhibitor KB-R7943 (3 or 10 microM) had no significant effect on HPV. Combined treatment with ouabain and low-[Na(+)] (24 mM) solution enhanced HPV strongly. The role of NCX in Ca(2+) extrusion was examined by assessing the decrease in [Ca(2+)](i) in Ca(2+)-free physiological saline solution either containing or lacking Na(+) following a high K(+)-induced loading of cellular [Ca(2+)]. Although the large initial rapid fall in [Ca(2+)] was Na(+) independent, final recovery of [Ca(2+)] to its basal level was delayed in the absence of Na(+). Therefore, HPV persisted or was increased under conditions in which forward-mode NCX was already attenuated or prevented, demonstrating that inhibition of NCX by hypoxia is unlikely to initiate HPV. Instead, NCX appears to act to inhibit HPV as would be expected if it is functioning to extrude Ca(2+).
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Affiliation(s)
- Silke Becker
- Division of Asthma, Allergy, and Lung Biology, King's College London, London, United Kingdom
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Schoner W, Scheiner-Bobis G. Endogenous and exogenous cardiac glycosides: their roles in hypertension, salt metabolism, and cell growth. Am J Physiol Cell Physiol 2007; 293:C509-36. [PMID: 17494630 DOI: 10.1152/ajpcell.00098.2007] [Citation(s) in RCA: 341] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cardiotonic steroids (CTS), long used to treat heart failure, are endogenously produced in mammals. Among them are the hydrophilic cardenolide ouabain and the more hydrophobic cardenolide digoxin, as well as the bufadienolides marinobufagenin and telecinobufagin. The physiological effects of endogenous ouabain on blood pressure and cardiac activity are consistent with the "Na(+)-lag" hypothesis. This hypothesis assumes that, in cardiac and arterial myocytes, a CTS-induced local increase of Na(+) concentration due to inhibition of Na(+)/K(+)-ATPase leads to an increase of intracellular Ca(2+) concentration ([Ca(2+)](i)) via a backward-running Na(+)/Ca(2+) exchanger. The increase in [Ca(2+)](i) then activates muscle contraction. The Na(+)-lag hypothesis may best explain short-term and inotropic actions of CTS. Yet all data on the CTS-induced alteration of gene expression are consistent with another hypothesis, based on the Na(+)/K(+)-ATPase "signalosome," that describes the interaction of cardiac glycosides with the Na(+) pump as machinery activating various signaling pathways via intramembrane and cytosolic protein-protein interactions. These pathways, which may be activated simultaneously or selectively, elevate [Ca(2+)](i), activate Src and the ERK1/2 kinase pathways, and activate phosphoinositide 3-kinase and protein kinase B (Akt), NF-kappaB, and reactive oxygen species. A recent development indicates that new pharmaceuticals with antihypertensive and anticancer activities may be found among CTS and their derivatives: the antihypertensive rostafuroxin suppresses Na(+) resorption and the Src-epidermal growth factor receptor-ERK pathway in kidney tubule cells. It may be the parent compound of a new principle of antihypertensive therapy. Bufalin and oleandrin or the cardenolide analog UNBS-1450 block tumor cell proliferation and induce apoptosis at low concentrations in tumors with constitutive activation of NF-kappaB.
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Affiliation(s)
- Wilhelm Schoner
- Institut für Biochemie und Endokrinologie, Fachbereich Veterinärmedizin, Justus-Liebig-Universität Giessen, Frankfurter Str 100, Giessen, Germany.
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Syyong HT, Poburko D, Fameli N, van Breemen C. ATP promotes NCX-reversal in aortic smooth muscle cells by DAG-activated Na+ entry. Biochem Biophys Res Commun 2007; 357:1177-82. [PMID: 17466270 DOI: 10.1016/j.bbrc.2007.04.080] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Accepted: 04/13/2007] [Indexed: 10/23/2022]
Abstract
Reversal of the plasma membrane Na(+)/Ca(2+) exchanger (NCX) has been shown to mediate Ca(2+) influx in response to activation of G-protein linked receptors. Functional coupling of reverse-mode NCX with canonical transient receptor potential channels (TRPC), specifically TRPC6, has recently been demonstrated by our laboratory to mediate Ca(2+) influx in rat aortic smooth muscle cells (RASMCs) following ATP stimulation. In this communication, we provide further detail of this functional coupling by indirectly measuring NCX reversal. We found that NCX reversal, induced by the removal of extracellular Na(+), was increased following stimulation with ATP and the diacylglycerol analog 1-Oleoyl-2-acetyl-sn-glycerol. This increased NCX reversal was attenuated by SKF-96365, an inhibitor of non-selective cation channels, and by activation of protein kinase C with phorbol ester 12-tetradecanoylphorbol-13 acetate. These data are consistent with the known properties of TRPC6 and further support that functional coupling of TRPC6 and NCX occurs via a receptor-operated, rather than store-operated, cascade in RASMCs.
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Affiliation(s)
- Harley T Syyong
- Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, BC, Canada V6T 1Z1
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Gottlieb PA, Suchyna TM, Sachs F. Properties and Mechanism of the Mechanosensitive Ion Channel Inhibitor GsMTx4, a Therapeutic Peptide Derived from Tarantula Venom. CURRENT TOPICS IN MEMBRANES 2007; 59:81-109. [PMID: 25168134 DOI: 10.1016/s1063-5823(06)59004-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Mechanosensitive ion channels (MSCs) are found in all types of cells ranging from Escherichia coli to morning glories to humans. They seem to fall into two families: those in specialized receptors, such as the hair cells of the cochlea, and those in cells not clearly differentiated for sensory duty. The physiological function of the channels in nonspecialized cells has not been demonstrated, although their activity has been demonstrated innumerable times in vitro. The only specific reagent to block MSCs isGsMTx4, a 4-kDa peptide isolated from tarantula venom. Despite being isolated from venom, it is nontoxic to mice. GsMTx4 is specific for an MSC subtype, the nonselective cation channels that may be members of the transient receptor potential (TRP) family. GsMTx4 acts as a gating modifier, increasing the energy of the open state relative to the closed state. The mirror image D enantiomer of GsMTx4 is equally active, so mode of action is not via the traditional lock and key model. GsMTx4 probably acts in the boundary lipid of the channel by changing local curvature and mechanically stressing the channel toward the closed state. Despite the lack of definitive physiological data on the function of the cationic MSCs, GsMTx4 may prove useful as a drug or lead compound that can affect physiological processes. These processes would be those driven by mechanical stress, such as blood vessel autoregulation, stress-induced contraction of smooth muscle, and Ca(2+) loading in muscular dystrophy.
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Affiliation(s)
- Philip A Gottlieb
- The Department of Physiology and Biophysics, Center for Single Molecule Biophysics, SUNY at Buffalo, Buffalo, New York 14214
| | - Thomas M Suchyna
- The Department of Physiology and Biophysics, Center for Single Molecule Biophysics, SUNY at Buffalo, Buffalo, New York 14214
| | - Frederick Sachs
- The Department of Physiology and Biophysics, Center for Single Molecule Biophysics, SUNY at Buffalo, Buffalo, New York 14214
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Edwards A, Pallone TL. Modification of cytosolic calcium signaling by subplasmalemmal microdomains. Am J Physiol Renal Physiol 2007; 292:F1827-45. [PMID: 17311908 DOI: 10.1152/ajprenal.00387.2006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To investigate the hypothesis that Na(+) concentration in subplasmalemmal microdomains regulates Ca(2+) concentrations in cellular microdomains ([Ca](md)), the cytosol ([Ca](cyt)), and sarcoplasmic reticulum (SR; [Ca](sr)), we modeled transport events in those compartments. Inputs to the model were obtained from published measurements in descending vasa recta pericytes and other smooth muscle cells. The model accounts for major classes of ion channels, Na(+)/Ca(2+) exchange (NCX), and the distributions of Na(+)-K(+)-ATPase alpha(1)- and alpha(2)-isoforms in the plasma membrane. Ca(2+) release from SR stores is assumed to occur via ryanodine (RyR) and inositol trisphosphate (IP(3)R) receptors. The model shows that the requisite existence of a significant Na(+) concentration difference between the cytosol ([Na](cyt)) and microdomains ([Na](md)) necessitates restriction of intercompartmental diffusion. Accepting the latter, the model predicts resting ion concentrations that are compatible with experimental measurements and temporal changes in [Ca](cyt) similar to those observed on NCX inhibition. An important role for NCX in the regulation of Ca(2+) signaling is verified. In the resting state, NCX operates in "forward mode," with Na(+) entry and Ca(2+) extrusion from the cell. Inhibition of NCX respectively raises and reduces [Ca](cyt) and [Na](cyt) by 40 and 30%. NCX translates variations in Na(+)-K(+)-ATPase activity into changes in [Ca](md), [Ca](sr), and [Ca](cyt). Taken together, the model simulations verify the feasibility of the central hypothesis that modulation of [Na](md) can influence both the loading of Ca(2+) into SR stores and [Ca(2+)](cyt) variation.
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Affiliation(s)
- Aurélie Edwards
- Department of Chemical and Biological Engineering, Tufts University, Medford, MA 02155, USA.
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Abstract
The expression and function of the Na+/Ca2+ exchanger (NCX) in the regulation of intracellular Ca2+ homeostasis have been well studied in cardiac, skeletal, and systemic vascular myocytes, but not in pulmonary artery smooth muscle cells (SMCs). We have recently demonstrated that the NCX current is present in freshly isolated pulmonary artery SMCs using the patch-clamp technique. The current has a mean amplitude of 13 pA under near physiological resting conditions. The NCX may function in the forward mode to make a significant contribution to the decay of intracellular Ca2+ following Ca2+ release and/or depolarization. Hypoxic stimulation inhibits the NCX current, reduces the removal of intracellular Ca2+, and enhances Ca2+ release from the sarcoplasmic reticulum. Using RT-PCR, subcloning and sequence analysis, we have shown that three NCX1 splice variants: NCX1.2 (containing exons B, C, and D), NCX1.3 (exons B and D), and NCX1.7 (exons B, D, and F) are expressed in pulmonary artery smooth muscle. Each of these splice variants expressed in HEK293 cells it likely to show a distinct activity in the removal of intracellular Ca2+. Taken together, we provide clear evidence that NCX1 is functionally and molecularly expressed and plays a physiological role in pulmonary artery SMCs.
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Affiliation(s)
- Yun-Min Zheng
- Center for Cardiovascular Sciences, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA
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Chung WS, Farley JM. Tachyphylaxis to the inhibitory effect of L-type channel blockers on ACh-induced [Ca2+]i oscillations in porcine tracheal myocytes. J Biomed Sci 2007; 14:129-43. [PMID: 17278012 DOI: 10.1007/s11373-006-9122-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2006] [Accepted: 09/19/2006] [Indexed: 01/08/2023] Open
Abstract
Discrepancies about the role of L-type voltage-gated calcium channels (VGCC) in acetylcholine (ACh)-induced [Ca(2+)](i) oscillations in tracheal smooth muscle cells (TSMCs) have been seen in recent reports. We demonstrate here that ACh-induced [Ca(2+)](i) oscillations in TMCS were reversibly inhibited by three VGCC blockers, nicardipine, nifedipine and verapamil. Prolonged (several minutes) application of VGCC blockers, led to tachyphylaxis; that is, [Ca(2+)](i) oscillations resumed, but at a lower frequency. Brief (15-30 s) removal of VGCC blockers re-sensitized [Ca(2+)](i) oscillations to inhibition by the agents. Calcium oscillations tolerant to VGCC blockers were abolished by KB-R7943, an inhibitor of the reverse mode of Na(+)/Ca(2+) exchanger (NCX). KB-R7943 alone also abolished ACh-induced [Ca(2+)](i) oscillations. Enhancement of the reverse mode of NCX via removing extracellular Na(+) reversed inhibition of ACh-induced [Ca(2+)](i) oscillations by VGCC blockers. Inhibition of non-selective cation channels using Gd(3+) slightly reduced the frequency of ACh-induced [Ca(2+)](i) oscillations, but did not prevent the occurrence of tachyphylaxis. Altogether, these results suggest that VGCC and the reverse mode of NCX are two primary Ca(2+) entry pathways for maintaining ACh-induced [Ca(2+)](i) oscillations in TSMCs. The two pathways complement each other, and may account for tachyphylaxis of ACh-induced [Ca(2+)](i) oscillations to VGCC blockers.
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Affiliation(s)
- Wen-Shuo Chung
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
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Bowman CL, Gottlieb PA, Suchyna TM, Murphy YK, Sachs F. Mechanosensitive ion channels and the peptide inhibitor GsMTx-4: history, properties, mechanisms and pharmacology. Toxicon 2007; 49:249-70. [PMID: 17157345 PMCID: PMC1852511 DOI: 10.1016/j.toxicon.2006.09.030] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Sensing the energy from mechanical inputs is ubiquitous--and perhaps the oldest form of biological energy transduction. However, the tools available to probe the mechanisms of transduction are far fewer than for the chemical and electric field sensitive transducers. The one pharmacological tool available for mechansensitive ion channels (MSCs) is a peptide (GsMTx-4) isolated from venom of the tarantula, Grammostola spatulata, that blocks cationic MSCs found in non-specialized eukaryotic tissues. In this review, we summarize the current knowledge of GsMTx-4, and discuss the inevitable crosstalk between the MSC behavior and the mechanical properties of the cell cortex.
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Affiliation(s)
- Charles L Bowman
- Center for Single Molecule Biophysics and The Department of Physiology and Biophysics, SUNY at Buffalo, Buffalo, NY 14214, USA.
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