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Bo H, Heinzmann D, Grasshoff C, Rosenberger P, Schlensak C, Gawaz M, Schreieck J, Langer HF, Patzelt J, Seizer P. ECG changes after percutaneous edge-to-edge mitral valve repair. Clin Cardiol 2019; 42:1094-1099. [PMID: 31497886 PMCID: PMC6837028 DOI: 10.1002/clc.23258] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/17/2019] [Accepted: 08/27/2019] [Indexed: 01/22/2023] Open
Abstract
Background Mitral regurgitation (MR) has a severe impact on hemodynamics and induces severe structural changes in the left atrium. Atrial remodeling is known to alter excitability and conduction in the atrium facilitating atrial fibrillation and atrial flutter. PMVR is a feasible and highly effective procedure to reduce MR in high‐risk patients, which are likely to suffer from atrial rhythm disturbances. So far, electroanatomical changes after PMVR have not been studied. Hypothesis In the current study, we investigated changes in surface electrocardiograms (ECGs) of patients undergoing PMVR for reduction of MR. Methods We evaluated 104 surface ECGs from patients in sinus rhythm undergoing PMVR. P wave duration, P wave amplitude, PR interval, QRS duration, QRS axis, and QT interval were evaluated before and after PMVR and at follow‐up. Results We found no changes in QRS duration, QRS axis, and QT interval after successful PMVR. However, P wave duration, amplitude, and PR interval were significantly decreased after reduction of MR through PMVR (P < .05, respectively). Conclusion The data we provide offers insight into changes in atrial conduction after reduction of MR using PMVR in patients with sinus rhythm.
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Affiliation(s)
- Hou Bo
- Department of Cardiology and Angiology, University Hospital, Eberhard Karls University Tübingen, Tübingen, Germany.,Department of Cardiology, Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China
| | - David Heinzmann
- Department of Cardiology and Angiology, University Hospital, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Christian Grasshoff
- Department of Anaesthesiology, University Hospital, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Peter Rosenberger
- Department of Anaesthesiology, University Hospital, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Christian Schlensak
- Department of Cardiovascular Surgery, University Hospital, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Meinrad Gawaz
- Department of Cardiology and Angiology, University Hospital, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Jürgen Schreieck
- Department of Cardiology and Angiology, University Hospital, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Harald F Langer
- Medical Clinic II, Universitäres Herzzentrum Lübeck, University Hospital Schleswig-Holstein, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany
| | - Johannes Patzelt
- Medical Clinic II, Universitäres Herzzentrum Lübeck, University Hospital Schleswig-Holstein, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany
| | - Peter Seizer
- Department of Cardiology and Angiology, University Hospital, Eberhard Karls University Tübingen, Tübingen, Germany
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2
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Luo Q, Chen L, Cheng X, Ma Y, Li X, Zhang B, Li L, Zhang S, Guo F, Li Y, Yang H. An allosteric ligand-binding site in the extracellular cap of K2P channels. Nat Commun 2017; 8:378. [PMID: 28851868 PMCID: PMC5575254 DOI: 10.1038/s41467-017-00499-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 07/04/2017] [Indexed: 11/09/2022] Open
Abstract
Two-pore domain potassium (K2P) channels generate leak currents that are responsible for the maintenance of the resting membrane potential, and they are thus potential drug targets for treating diseases. Here, we identify N-(4-cholorphenyl)-N-(2-(3,4-dihydrosioquinolin-2(1H)-yl)-2-oxoethyl)methanesulfonamide (TKDC) as an inhibitor of the TREK subfamily, including TREK-1, TREK-2 and TRAAK channels. Using TKDC as a chemical probe, a study combining computations, mutagenesis and electrophysiology reveals a K2P allosteric ligand-binding site located in the extracellular cap of the channels. Molecular dynamics simulations suggest that ligand-induced allosteric conformational transitions lead to blockage of the ion conductive pathway. Using virtual screening approach, we identify other inhibitors targeting the extracellular allosteric ligand-binding site of these channels. Overall, our results suggest that the allosteric site at the extracellular cap of the K2P channels might be a promising drug target for these membrane proteins. TREKs are members of the two-pore domain potassium (K2P) channels, being important clinical targets. Here the authors identify inhibitors of K2P that bind to an allosteric site located in their extracellular cap, suggesting that it might be a promising drug target for these channels.
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Affiliation(s)
- Qichao Luo
- State Key Laboratory of Drug Research and Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China
| | - Liping Chen
- State Key Laboratory of Drug Research and Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China
| | - Xi Cheng
- State Key Laboratory of Drug Research and Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China
| | - Yuqin Ma
- State Key Laboratory of Drug Research and Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China
| | - Xiaona Li
- State Key Laboratory of Drug Research and Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China
| | - Bing Zhang
- State Key Laboratory of Drug Research and Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China
| | - Li Li
- State Key Laboratory of Drug Research and Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China
| | - Shilei Zhang
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases & Department of Medicinal Chemistry, College of Pharmaceutical Sciences, Soochow University, 199 Ren'ai Road, Suzhou, 215123, China
| | - Fei Guo
- State Key Laboratory of Drug Research and Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China
| | - Yang Li
- State Key Laboratory of Drug Research and Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China. .,University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China.
| | - Huaiyu Yang
- State Key Laboratory of Drug Research and Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China. .,University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, China. .,Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China.
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3
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A RhoA and Rnd3 cycle regulates actin reassembly during membrane blebbing. Proc Natl Acad Sci U S A 2016; 113:E1863-71. [PMID: 26976596 DOI: 10.1073/pnas.1600968113] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The actin cytoskeleton usually lies beneath the plasma membrane. When the membrane-associated actin cytoskeleton is transiently disrupted or the intracellular pressure is increased, the plasma membrane detaches from the cortex and protrudes. Such protruded membrane regions are called blebs. However, the molecular mechanisms underlying membrane blebbing are poorly understood. This study revealed that epidermal growth factor receptor kinase substrate 8 (Eps8) and ezrin are important regulators of rapid actin reassembly for the initiation and retraction of protruded blebs. Live-cell imaging of membrane blebbing revealed that local reassembly of actin filaments occurred at Eps8- and activated ezrin-positive foci of membrane blebs. Furthermore, we found that a RhoA-ROCK-Rnd3 feedback loop determined the local reassembly sites of the actin cortex during membrane blebbing.
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4
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Cox CD, Bae C, Ziegler L, Hartley S, Nikolova-Krstevski V, Rohde PR, Ng CA, Sachs F, Gottlieb PA, Martinac B. Removal of the mechanoprotective influence of the cytoskeleton reveals PIEZO1 is gated by bilayer tension. Nat Commun 2016; 7:10366. [PMID: 26785635 PMCID: PMC4735864 DOI: 10.1038/ncomms10366] [Citation(s) in RCA: 322] [Impact Index Per Article: 40.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 12/04/2015] [Indexed: 12/18/2022] Open
Abstract
Mechanosensitive ion channels are force-transducing enzymes that couple mechanical stimuli to ion flux. Understanding the gating mechanism of mechanosensitive channels is challenging because the stimulus seen by the channel reflects forces shared between the membrane, cytoskeleton and extracellular matrix. Here we examine whether the mechanosensitive channel PIEZO1 is activated by force-transmission through the bilayer. To achieve this, we generate HEK293 cell membrane blebs largely free of cytoskeleton. Using the bacterial channel MscL, we calibrate the bilayer tension demonstrating that activation of MscL in blebs is identical to that in reconstituted bilayers. Utilizing a novel PIEZO1-GFP fusion, we then show PIEZO1 is activated by bilayer tension in bleb membranes, gating at lower pressures indicative of removal of the cortical cytoskeleton and the mechanoprotection it provides. Thus, PIEZO1 channels must sense force directly transmitted through the bilayer.
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Affiliation(s)
- Charles D. Cox
- Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia
| | - Chilman Bae
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York 14214, USA
| | - Lynn Ziegler
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York 14214, USA
| | - Silas Hartley
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York 14214, USA
| | | | - Paul R. Rohde
- Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia
| | - Chai-Ann Ng
- Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia
- St Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales 2010, Australia
| | - Frederick Sachs
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York 14214, USA
- The Centre for Single Molecule Biophysics, State University of New York at Buffalo, Buffalo, New York 14214, USA
| | - Philip A. Gottlieb
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York 14214, USA
- The Centre for Single Molecule Biophysics, State University of New York at Buffalo, Buffalo, New York 14214, USA
| | - Boris Martinac
- Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales 2010, Australia
- St Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales 2010, Australia
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5
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Schneider ER, Anderson EO, Gracheva EO, Bagriantsev SN. Temperature sensitivity of two-pore (K2P) potassium channels. CURRENT TOPICS IN MEMBRANES 2014; 74:113-33. [PMID: 25366235 DOI: 10.1016/b978-0-12-800181-3.00005-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
At normal body temperature, the two-pore potassium channels TREK-1 (K2P2.1/KCNK2), TREK-2 (K2P10.1/KCNK10), and TRAAK (K2P4.1/KCNK2) regulate cellular excitability by providing voltage-independent leak of potassium. Heat dramatically potentiates K2P channel activity and further affects excitation. This review focuses on the current understanding of the physiological role of heat-activated K2P current, and discusses the molecular mechanism of temperature gating in TREK-1, TREK-2, and TRAAK.
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Affiliation(s)
- Eve R Schneider
- Department of Cellular & Molecular Physiology, Yale School of Medicine, New Haven, CT, USA
| | - Evan O Anderson
- Department of Cellular & Molecular Physiology, Yale School of Medicine, New Haven, CT, USA
| | - Elena O Gracheva
- Department of Cellular & Molecular Physiology, Yale School of Medicine, New Haven, CT, USA; Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale School of Medicine, New Haven, CT, USA
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6
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Takahashi K, Naruse K. Stretch-activated BK channel and heart function. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2013; 110:239-44. [PMID: 23281538 DOI: 10.1016/j.pbiomolbio.2012.08.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The heart is an organ that is exposed to extreme dynamic mechanical stimuli. From birth till death, the heart indefinitely repeats periodic contraction and dilation, i.e., shortening and elongation of cardiomyocytes. Mechanical stretch elicits a change in heart rate and may cause arrhythmia if it is excessive. Thus, mechanosensitivity is crucial to heart function. The molecule that is substantially involved in mechanosensitivity is a stretch-activated ion channel. Among several ion channels believed to be activated by stretch in the heart, the stretch-activated KCa (SAKCA) channel, a member of the group of large conductance (Big Potassium, BK) channels, shows a mechanosensitive (MS) response to membrane stretch. As BK channels respond to voltage and intracellular calcium concentration with large conductance, they are considered to be involved in repolarization after depolarization. Some BK channels are known to be activated by stretch and are expressed in a number of cells, including human osteoblasts and guinea pig intestinal neurons. The SAKCA channel was found to be sensitive to stretch in the chick heart. Given that the cardiomyocyte is unremittingly exposed to contraction and dilation and that it generates action potential and its contractility is modulated by intracellular calcium concentration, the SAKCA channel, which is dependent voltage and calcium, may be involved in action potential generation. It was recently reported that a BK channel is involved in the modulation of heart rate in the mouse. Further studies regarding the role of MS BK channels, including SAKCA, in the modulation of heart rate and contractility are expected.
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Affiliation(s)
- Ken Takahashi
- Department of Cardiovascular Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.
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7
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An increased TREK-1-like potassium current in ventricular myocytes during rat cardiac hypertrophy. J Cardiovasc Pharmacol 2013; 61:302-10. [PMID: 23232841 DOI: 10.1097/fjc.0b013e318280c5a9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
To elucidate the expression and identify the functional changes of 2 pore domain potassium channel TREK-1 during cardiac hypertrophy in rats, left ventricular hypertrophy was induced by subcutaneous injection with isoproterenol. Western blot was used to detect the expression of TREK-1 channel protein, and inside-out and whole-cell recordings were used to record TREK-1 currents. The results showed that TREK-1 protein expression in endocardium was slightly higher than that in epicardium in control left ventricles. However, it was obviously upregulated by 89.8% during hypertrophy, 2.3-fold higher than in epicardium. Mechanical stretch, intracellular acidification, and arachidonic acid could activate a TREK-1-like current in cardiomyocytes. The slope conductances of cardiac TREK-1 and CHO/TREK-1 channels were 123 ± 7 and 113 ± 17 pS, respectively. The TREK-1 inhibitor L-3-n-butylphthalide (10 μM) reduced the currents in CHO/TREK-1 cells, normal cardiomyocytes, and hypertrophic cardiomyocytes by 48.5%, 54.3%, and 55.5%, respectively. The percentage of L-3-n-butylphthalide-inhibited outward whole-cell current in hypertrophic cardiomyocytes (23.7%) was larger than that in normal cardiomyocytes (14.2%). The percentage of chloroform-activated outward whole-cell current in hypertrophic cardiomyocytes (58.3%) was also larger than normal control (40.2%). Our results demonstrated that in hypertrophic rats, TREK-1 protein expression in endocardium was specifically increased and the ratio of TREK-1 channel current in cardiac outward currents was also enhanced. TREK-1 might balance potassium ion flow during hypertrophy and might be a potential drug target for heart protection.
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8
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Shear stress triggers insertion of voltage-gated potassium channels from intracellular compartments in atrial myocytes. Proc Natl Acad Sci U S A 2013; 110:E3955-64. [PMID: 24065831 DOI: 10.1073/pnas.1309896110] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Atrial myocytes are continuously exposed to mechanical forces including shear stress. However, in atrial myocytes, the effects of shear stress are poorly understood, particularly with respect to its effect on ion channel function. Here, we report that shear stress activated a large outward current from rat atrial myocytes, with a parallel decrease in action potential duration. The main ion channel underlying the increase in current was found to be Kv1.5, the recruitment of which could be directly observed by total internal reflection fluorescence microscopy, in response to shear stress. The effect was primarily attributable to recruitment of intracellular pools of Kv1.5 to the sarcolemma, as the response was prevented by the SNARE protein inhibitor N-ethylmaleimide and the calcium chelator BAPTA. The process required integrin signaling through focal adhesion kinase and relied on an intact microtubule system. Furthermore, in a rat model of chronic hemodynamic overload, myocytes showed an increase in basal current despite a decrease in Kv1.5 protein expression, with a reduced response to shear stress. Additionally, integrin beta1d expression and focal adhesion kinase activation were increased in this model. This data suggests that, under conditions of chronically increased mechanical stress, the integrin signaling pathway is overactivated, leading to increased functional Kv1.5 at the membrane and reducing the capacity of cells to further respond to mechanical challenge. Thus, pools of Kv1.5 may comprise an inducible reservoir that can facilitate the repolarization of the atrium under conditions of excessive mechanical stress.
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9
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Force spectroscopy measurements show that cortical neurons exposed to excitotoxic agonists stiffen before showing evidence of bleb damage. PLoS One 2013; 8:e73499. [PMID: 24023686 PMCID: PMC3758302 DOI: 10.1371/journal.pone.0073499] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 07/22/2013] [Indexed: 12/12/2022] Open
Abstract
In ischemic and traumatic brain injury, hyperactivated glutamate (N-methyl-D-aspartic acid, NMDA) and sodium (Nav) channels trigger excitotoxic neuron death. Na+, Ca++ and H2O influx into affected neurons elicits swelling (increased cell volume) and pathological blebbing (disassociation of the plasma membrane’s bilayer from its spectrin-actomyosin matrix). Though usually conflated in injured tissue, cell swelling and blebbing are distinct processes. Around an injury core, salvageable neurons could be mildly swollen without yet having suffered the bleb-type membrane damage that, by rendering channels leaky and pumps dysfunctional, exacerbates the excitotoxic positive feedback spiral. Recognizing when neuronal inflation signifies non-lethal osmotic swelling versus blebbing should further efforts to salvage injury-penumbra neurons. To assess whether the mechanical properties of osmotically-swollen versus excitotoxically-blebbing neurons might be cytomechanically distinguishable, we measured cortical neuron elasticity (gauged via atomic force microscopy (AFM)-based force spectroscopy) upon brief exposure to hypotonicity or to excitotoxic agonists (glutamate and Nav channel activators, NMDA and veratridine). Though unperturbed by solution exchange per se, elasticity increased abruptly with hypotonicity, with NMDA and with veratridine. Neurons then invariably softened towards or below the pre-treatment level, sometimes starting before the washout. The initial channel-mediated stiffening bespeaks an abrupt elevation of hydrostatic pressure linked to NMDA or Nav channel-mediated ion/H2O fluxes, together with increased [Ca++]int-mediated submembrane actomyosin contractility. The subsequent softening to below-control levels is consistent with the onset of a lethal level of bleb damage. These findings indicate that dissection/identification of molecular events during the excitotoxic transition from stiff/swollen to soft/blebbing is warranted and should be feasible.
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10
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Huang H, Liang L, Liu P, Wei H, Sachs F, Niu W, Wang W. Mechanical effects on KATP channel gating in rat ventricular myocytes. PLoS One 2013; 8:e63337. [PMID: 23691027 PMCID: PMC3653899 DOI: 10.1371/journal.pone.0063337] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 04/02/2013] [Indexed: 11/18/2022] Open
Abstract
Cardiac KATP channels link metabolism with electrical activity. They are implicated in arrhythmias, secretion of atrial natriuretic peptide and protection of the heart from hypertrophy and failure. These processes may involve mechanosensitivity. KATP channels can be activated by mechanical stimulation and disrupting the cortical actin increases the activity. We propose that KATP channels are modulated by local bilayer tension and this tension is affected by cortical F-actin. Here we measured KATP background activity and stretch sensitivity with inside-out patches of rat ventricular myocytes before and after disrupting F-actin. Disrupting F-actin potentiated background activity but did not influence the slope sensitivity in the semilog relationship of NPo vs. suction that is a measure of the change in dimensions between closed and open states. Thus actin alters prestress on the channel probably by parallel elastic sharing of mean cortical tension with the bilayer.
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Affiliation(s)
- Haixia Huang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Lifang Liang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Ping Liu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Hua Wei
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Frederick Sachs
- Department of Physiology and Biophysics, SUNY, Buffalo, New York, United States of America
| | - Weizhen Niu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Wei Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
- * E-mail:
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Huang H, Wang W, Liu P, Jiang Y, Zhao Y, Wei H, Niu W. TRPC1 expression and distribution in rat hearts. Eur J Histochem 2012; 53:e26. [PMID: 22073358 PMCID: PMC3167335 DOI: 10.4081/ejh.2009.e26] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/09/2009] [Indexed: 12/31/2022] Open
Abstract
Transient receptor potential canonical (TRPC) proteins have been identified as a family of plasma membrane calcium-permeable channels. TRPC proteins can be activated by various stimuli and act as cellular sensors in mammals. Stretch-activated ion channels (SACs) have been proposed to underlie cardiac mechano-electric feedback (MEF), although the molecular entity of SAC remains unknown. There is evidence suggesting that transient receptor potential canonical 1 (TRPC1) is a stretch-activated ion channel. As a non-selective cation channel, TRPC1 may cause stretch-induced depolarization and arrhythmia and thus may contribute to the MEF of the heart. In this study, we examined the expression patterns of TRPC1 in detail at both the mRNA and protein levels in rat hearts. We isolated total RNA from the left and right atria, and the left and right ventricles, and detected TRPC1 mRNA in these tissues using reverse-transcriptase polymerase chain reaction (RT-PCR). To study the protein localization and targeting, we performed immunohistochemistry and immunofluorescence labeling with the antibody against TRPC1. TRPC1 was detected in the cardiomyocytes of the ventricle and atrium at both the mRNA and protein levels. The cell membrane and T-tubule showed strong fluorescence labeling in the ventricular myocytes. Purkinje cells, the endothelial cells and smooth muscle cells of the coronary arterioles also displayed TRPC1 labeling. No TRPC1 was detected in fibroblasts. In conclusion, TRPC1 is widely expressed in the rat heart, including in working cells, Purkinje cells and vascular cells, suggesting that it plays an important role in the heart. The specific distribution pattern offered a useful insight into its function in adult rat ventricular cells. Further investigations are needed to clarify the role of TRPC1 in regulating cardiac activity, including cardiac MEF.
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Affiliation(s)
- H Huang
- Department of Physiology, Capital Medical University, Beijing, China
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12
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Namiranian K, Lloyd EE, Crossland RF, Marrelli SP, Taffet GE, Reddy AK, Hartley CJ, Bryan RM. Cerebrovascular responses in mice deficient in the potassium channel, TREK-1. Am J Physiol Regul Integr Comp Physiol 2010; 299:R461-9. [PMID: 20357027 PMCID: PMC2928619 DOI: 10.1152/ajpregu.00057.2010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 03/30/2010] [Indexed: 12/19/2022]
Abstract
We tested the hypothesis that TREK-1, a two-pore domain K channel, is involved with dilations in arteries. Because there are no selective activators or inhibitors of TREK-1, we generated a mouse line deficient in TREK-1. Endothelium-mediated dilations were not different in arteries from wild-type (WT) and TREK-1 knockout (KO) mice. This includes dilations of the middle cerebral artery to ATP, dilations of the basilar artery to ACh, and relaxations of the aorta to carbachol, a cholinergic agonist. The nitric oxide (NO) and endothelium-dependent hyperpolarizing factor components of ATP dilations were identical in the middle cerebral arteries of WT and TREK-1 KO mice. Furthermore, the NO and cyclooxygenase-dependent components were identical in the basilar arteries of the different genotypes. Dilations of the basilar artery to alpha-linolenic acid, an activator of TREK-1, were not affected by the absence of TREK-1. Whole cell currents recorded using patch-clamp techniques were similar in cerebrovascular smooth muscle cells (CVSMCs) from WT and TREK-1 KO mice. alpha-linolenic acid or arachidonic acid increased whole cell currents in CVSMCs from both WT and TREK-1 KO mice. The selective blockers of large-conductance Ca-activated K channels, penitrem A and iberiotoxin, blocked the increased currents elicited by either alpha-linolenic or arachidonic acid. In summary, dilations were similar in arteries from WT and TREK-1 KO mice. There was no sign of TREK-1-like currents in CVSMCs from WT mice, and there were no major differences in currents between the genotypes. We conclude that regulation of arterial diameter is not altered in mice lacking TREK-1.
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Affiliation(s)
- Khodadad Namiranian
- Department of Anesthesiology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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Huang H, Wei H, Liu P, Wang W, Sachs F, Niu W. A simple automated stimulator of mechanically induced arrhythmias in the isolated rat heart. Exp Physiol 2009; 94:1054-61. [PMID: 19592413 DOI: 10.1113/expphysiol.2009.048660] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Transient stretching of the ventricle can trigger arrhythmias and evoke ventricular fibrillation, especially when the stimulation occurs in the vulnerable period. To explore the sensitivity of small hearts we used a commercial pressure servo to study the kinetic relationship of left ventricular pressure to excitability and arrhythmias in the rat heart. Stimulation protocols were readily composed on the computer and programmed to vary the stimulus amplitude and timing relative to pacing. The pressure-induced premature ventricular excitations were similar to those observed in larger hearts, but the convenience of using small hearts allows the use of inexpensive transgenic animals to explore the molecular basis of transduction.
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Affiliation(s)
- Haixia Huang
- Department of Physiology and Pathophysiology, Capital Medical University, Beijing 100069, People's Republic of China
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