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  1. Article ; Online: Sarcolemmal distribution of

    Gadeberg, Hanne C / Kong, Cherrie H T / Bryant, Simon M / James, Andrew F / Orchard, Clive H

    American journal of physiology. Heart and circulatory physiology

    2017  Volume 313, Issue 1, Page(s) H190–H199

    Abstract: The balance of ... ...

    Abstract The balance of Ca
    MeSH term(s) Animals ; Calcium/metabolism ; Calcium Signaling/physiology ; Cells, Cultured ; Heart Ventricles/cytology ; Heart Ventricles/metabolism ; Homeostasis ; Ion Channel Gating/physiology ; Male ; Mice ; Mice, Inbred C57BL ; Myocytes, Cardiac/cytology ; Myocytes, Cardiac/physiology ; Sarcolemma/metabolism ; Sodium-Calcium Exchanger/metabolism
    Chemical Substances Sodium-Calcium Exchanger ; Calcium (SY7Q814VUP)
    Language English
    Publishing date 2017-05-05
    Publishing country United States
    Document type Journal Article
    ZDB-ID 603838-4
    ISSN 1522-1539 ; 0363-6135
    ISSN (online) 1522-1539
    ISSN 0363-6135
    DOI 10.1152/ajpheart.00117.2017
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: The acid test.

    Orchard, Clive H

    Journal of molecular and cellular cardiology

    2003  Volume 36, Issue 1, Page(s) 21–24

    MeSH term(s) Acidosis/physiopathology ; Animals ; Calcium/metabolism ; Muscle Contraction ; Sarcoplasmic Reticulum/metabolism
    Chemical Substances Calcium (SY7Q814VUP)
    Language English
    Publishing date 2003-09-01
    Publishing country England
    Document type Comment ; Editorial ; Research Support, Non-U.S. Gov't
    ZDB-ID 80157-4
    ISSN 1095-8584 ; 0022-2828
    ISSN (online) 1095-8584
    ISSN 0022-2828
    DOI 10.1016/j.yjmcc.2003.10.018
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Solute movement in the t-tubule system of rabbit and mouse cardiomyocytes.

    Kong, Cherrie H T / Rog-Zielinska, Eva A / Kohl, Peter / Orchard, Clive H / Cannell, Mark B

    Proceedings of the National Academy of Sciences of the United States of America

    2018  Volume 115, Issue 30, Page(s) E7073–E7080

    Abstract: Cardiac transverse (t-) tubules carry both electrical excitation and solutes toward the cell center but their ability to transport small molecules is unclear. While fluorescence recovery after photobleaching (FRAP) can provide an approach to measure ... ...

    Abstract Cardiac transverse (t-) tubules carry both electrical excitation and solutes toward the cell center but their ability to transport small molecules is unclear. While fluorescence recovery after photobleaching (FRAP) can provide an approach to measure local solute movement, extraction of diffusion coefficients is confounded by cell and illumination beam geometries. In this study, we use measured cellular geometry and detailed computer modeling to derive the apparent diffusion coefficient of a 1-kDa solute inside the t-tubular system of rabbit and mouse ventricular cardiomyocytes. This approach shows that diffusion within individual t-tubules is more rapid than previously reported. T-tubule tortuosity, varicosities, and the presence of longitudinal elements combine to substantially reduce the apparent rate of solute movement. In steady state, large (>4 kDa) solutes did not freely fill the t-tubule lumen of both species and <50% of the t-tubule volume was available to solutes >70 kDa. Detailed model fitting of FRAP data suggests that solute diffusion is additionally restricted at the t-tubular entrance and this effect was larger in mouse than in rabbit. The possible structural basis of this effect was investigated using electron microscopy and tomography. Near the cell surface, mouse t-tubules are more tortuous and filled with an electron-dense ground substance, previously identified as glycocalyx and a polyanionic mesh. Solute movement in the t-tubule network of rabbit and mouse appears to be explained by their different geometric properties, which impacts the use of these species for understanding t-tubule function and the consequences of changes associated with t-tubule disease.
    MeSH term(s) Animals ; Biological Transport, Active/physiology ; Heart Ventricles/cytology ; Heart Ventricles/metabolism ; Male ; Mice ; Models, Cardiovascular ; Myocytes, Cardiac/cytology ; Myocytes, Cardiac/metabolism ; Rabbits
    Language English
    Publishing date 2018-07-10
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.1805979115
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  4. Article ; Online: Loss of caveolin-3-dependent regulation of I

    Bryant, Simon M / Kong, Cherrie H T / Cannell, Mark B / Orchard, Clive H / James, Andrew F

    American journal of physiology. Heart and circulatory physiology

    2017  Volume 314, Issue 3, Page(s) H521–H529

    Abstract: ... ...

    Abstract β
    MeSH term(s) Action Potentials ; Animals ; Calcium Channels, L-Type/metabolism ; Calcium Signaling ; Caveolin 3/metabolism ; Cyclic AMP/metabolism ; Cyclic AMP-Dependent Protein Kinases/metabolism ; Disease Models, Animal ; Heart Failure/metabolism ; Heart Failure/physiopathology ; Male ; Myocardial Infarction/metabolism ; Myocardial Infarction/physiopathology ; Myocytes, Cardiac/metabolism ; Protein Transport ; Rats, Wistar ; Receptors, Adrenergic, beta-2/metabolism
    Chemical Substances Calcium Channels, L-Type ; Cav3 protein, rat ; Caveolin 3 ; Receptors, Adrenergic, beta-2 ; Cyclic AMP (E0399OZS9N) ; Cyclic AMP-Dependent Protein Kinases (EC 2.7.11.11)
    Language English
    Publishing date 2017-11-03
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 603838-4
    ISSN 1522-1539 ; 0363-6135
    ISSN (online) 1522-1539
    ISSN 0363-6135
    DOI 10.1152/ajpheart.00458.2017
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Cholesterol depletion does not alter the capacitance or Ca handling of the surface or t-tubule membranes in mouse ventricular myocytes.

    Gadeberg, Hanne C / Kong, Cherrie H T / Bryant, Simon M / James, Andrew F / Orchard, Clive H

    Physiological reports

    2017  Volume 5, Issue 22

    Abstract: Cholesterol is a key component of the cell plasma membrane. It has been suggested that the t-tubule membrane of cardiac ventricular myocytes is enriched in cholesterol and that this plays a role in determining t-tubule structure and function. We have ... ...

    Abstract Cholesterol is a key component of the cell plasma membrane. It has been suggested that the t-tubule membrane of cardiac ventricular myocytes is enriched in cholesterol and that this plays a role in determining t-tubule structure and function. We have used methyl-
    MeSH term(s) Animals ; Calcium/metabolism ; Calcium Signaling ; Cell Membrane Structures/drug effects ; Cell Membrane Structures/metabolism ; Cell Membrane Structures/physiology ; Cells, Cultured ; Cholesterol/metabolism ; Heart Ventricles/cytology ; Membrane Potentials ; Mice ; Mice, Inbred C57BL ; Myocytes, Cardiac/drug effects ; Myocytes, Cardiac/metabolism ; Myocytes, Cardiac/physiology ; beta-Cyclodextrins/pharmacology
    Chemical Substances beta-Cyclodextrins ; methyl-beta-cyclodextrin ; Cholesterol (97C5T2UQ7J) ; Calcium (SY7Q814VUP)
    Language English
    Publishing date 2017-11-17
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2724325-4
    ISSN 2051-817X ; 2051-817X
    ISSN (online) 2051-817X
    ISSN 2051-817X
    DOI 10.14814/phy2.13500
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Effect of Ca2+ efflux pathway distribution and exogenous Ca2+ buffers on intracellular Ca2+ dynamics in the rat ventricular myocyte: a simulation study.

    Pásek, Michal / Simurda, Jiří / Orchard, Clive H

    BioMed research international

    2014  Volume 2014, Page(s) 920208

    Abstract: We have used a previously published computer model of the rat cardiac ventricular myocyte to investigate the effect of changing the distribution of Ca(2+) efflux pathways (SERCA, Na(+)/Ca(2+) exchange, and sarcolemmal Ca(2+) ATPase) between the dyad and ... ...

    Abstract We have used a previously published computer model of the rat cardiac ventricular myocyte to investigate the effect of changing the distribution of Ca(2+) efflux pathways (SERCA, Na(+)/Ca(2+) exchange, and sarcolemmal Ca(2+) ATPase) between the dyad and bulk cytoplasm and the effect of adding exogenous Ca(2+) buffers (BAPTA or EGTA), which are used experimentally to differentially buffer Ca(2+) in the dyad and bulk cytoplasm, on cellular Ca(2+) cycling. Increasing the dyadic fraction of a particular Ca(2+) efflux pathway increases the amount of Ca(2+) removed by that pathway, with corresponding changes in Ca(2+) efflux from the bulk cytoplasm. The magnitude of these effects varies with the proportion of the total Ca(2+) removed from the cytoplasm by that pathway. Differences in the response to EGTA and BAPTA, including changes in Ca(2+)-dependent inactivation of the L-type Ca(2+) current, resulted from the buffers acting as slow and fast "shuttles," respectively, removing Ca(2+) from the dyadic space. The data suggest that complex changes in dyadic Ca(2+) and cellular Ca(2+) cycling occur as a result of changes in the location of Ca(2+) removal pathways or the presence of exogenous Ca(2+) buffers, although changing the distribution of Ca(2+) efflux pathways has relatively small effects on the systolic Ca(2+) transient.
    MeSH term(s) Animals ; Buffers ; Calcium/metabolism ; Cell Compartmentation ; Computer Simulation ; Egtazic Acid/analogs & derivatives ; Egtazic Acid/pharmacology ; Heart Ventricles/cytology ; Intracellular Space/drug effects ; Intracellular Space/metabolism ; Ion Channel Gating/drug effects ; Models, Biological ; Myocytes, Cardiac/drug effects ; Myocytes, Cardiac/metabolism ; Rats ; Sarcolemma/drug effects ; Sarcolemma/metabolism ; Sodium-Calcium Exchanger/metabolism ; Time Factors
    Chemical Substances Buffers ; Sodium-Calcium Exchanger ; Egtazic Acid (526U7A2651) ; 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (K22DDW77C0) ; Calcium (SY7Q814VUP)
    Language English
    Publishing date 2014-05-29
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2698540-8
    ISSN 2314-6141 ; 2314-6133
    ISSN (online) 2314-6141
    ISSN 2314-6133
    DOI 10.1155/2014/920208
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Caveolin 3-dependent loss of t-tubular I

    Bryant, Simon M / Kong, Cherrie H T / Watson, Judy J / Gadeberg, Hanne C / James, Andrew F / Cannell, Mark B / Orchard, Clive H

    Experimental physiology

    2018  Volume 103, Issue 5, Page(s) 652–665

    Abstract: New findings: What is the central question of this study? Heart failure is associated with redistribution of L-type Ca: Abstract: Previous work has shown redistribution of L-type ... ...

    Abstract New findings: What is the central question of this study? Heart failure is associated with redistribution of L-type Ca
    Abstract: Previous work has shown redistribution of L-type Ca
    MeSH term(s) Animals ; Calcium Channels, L-Type/metabolism ; Calcium Signaling/physiology ; Cardiomegaly/metabolism ; Cardiomegaly/physiopathology ; Caveolin 3/metabolism ; Excitation Contraction Coupling/physiology ; Heart Failure/metabolism ; Heart Failure/physiopathology ; Heart Ventricles/metabolism ; Heart Ventricles/physiopathology ; Male ; Membrane Proteins/metabolism ; Mice ; Mice, Inbred C57BL ; Myocardial Infarction/metabolism ; Myocardial Infarction/pathology ; Myocytes, Cardiac/metabolism ; Myocytes, Cardiac/pathology ; Rats
    Chemical Substances Calcium Channels, L-Type ; Caveolin 3 ; Membrane Proteins ; junctophilin
    Language English
    Publishing date 2018-04-14
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1016295-1
    ISSN 1469-445X ; 0958-0670
    ISSN (online) 1469-445X
    ISSN 0958-0670
    DOI 10.1113/EP086731
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  8. Article ; Online: Sub-microscopic analysis of t-tubule geometry in living cardiac ventricular myocytes using a shape-based analysis method.

    Kong, Cherrie H T / Rog-Zielinska, Eva A / Orchard, Clive H / Kohl, Peter / Cannell, Mark B

    Journal of molecular and cellular cardiology

    2017  Volume 108, Page(s) 1–7

    Abstract: Transverse-axial tubules (TTs) are key structures involved in cardiac excitation-contraction coupling and can become deranged in disease. Although optical measurement of TTs is frequently employed to assess TT abundance and regularity, TT dimensions are ... ...

    Abstract Transverse-axial tubules (TTs) are key structures involved in cardiac excitation-contraction coupling and can become deranged in disease. Although optical measurement of TTs is frequently employed to assess TT abundance and regularity, TT dimensions are generally below the diffraction limit of optical microscopy so determination of tubule size is problematic. TT diameter was measured by labeling both local surface membrane area and volume with fluorescent probes (FM4-64 and calcein, respectively), correcting image asymmetry by image processing and using the relationship between surface area and volume for a geometric primitive. This method shows that TTs have a mean (±SEM) diameter of 356±18nm in rabbit and 169±15nm in mouse (p<0.001). Rabbit TT diameters were more variable than those of mouse (p<0.01) and the smallest TT detected was 41nm in mouse and the largest 695nm in rabbit. These estimates are consistent with TT diameters derived from the more limited sampling of high-pressure frozen samples by electron tomography (which examines only a small fraction of the cell volume). Other measures of TT abundance and geometry (such as volume, membrane fractions and direction) were also derived. On the physiological time scale of E-C coupling (milliseconds), the average TT electrical space constant is ~175μm in rabbit and ~120μm in mouse and is ~50% of the steady-state space constant. This is sufficient to ensure reasonable electrical uniformity across normal cells. The image processing strategy and shape-based 3D approach to feature quantification is also generally applicable to other problems in quantification of sub-cellular anatomy.
    MeSH term(s) Animals ; Heart Ventricles/cytology ; Image Processing, Computer-Assisted ; Mice ; Microscopy, Confocal ; Myocytes, Cardiac/cytology ; Myocytes, Cardiac/metabolism ; Myocytes, Cardiac/ultrastructure ; Rabbits ; Sarcoplasmic Reticulum/metabolism ; Sarcoplasmic Reticulum/ultrastructure
    Language English
    Publishing date 2017-05-05
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 80157-4
    ISSN 1095-8584 ; 0022-2828
    ISSN (online) 1095-8584
    ISSN 0022-2828
    DOI 10.1016/j.yjmcc.2017.05.003
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Ca efflux via the sarcolemmal Ca ATPase occurs only in the t-tubules of rat ventricular myocytes.

    Chase, Anabelle / Orchard, Clive H

    Journal of molecular and cellular cardiology

    2010  Volume 50, Issue 1, Page(s) 187–193

    Abstract: ... extrusion via NCX occurs across the surface and t-tubule membranes. The PKA inhibitor H-89 (10 μmol/L) was ... used to investigate the role of basal PKA activity in Ca extrusion; H-89 appeared to have no effect ...

    Abstract The transverse (t-) tubule network is an important site for Ca influx and release during excitation-contraction coupling in cardiac ventricular myocytes; however, its role in Ca extrusion is less clear. The present study was designed to investigate the relative contributions of Ca extrusion pathways across the t-tubule and surface membranes. Ventricular myocytes were isolated from the hearts of adult male Wistar rats and detubulated using formamide. Intracellular Ca was monitored using fluo-3 and confocal microscopy. Caffeine (20 mmol/L) was used to induce SR Ca release; carboxyeosin (20 μmol/L) and nickel (10 mmol/L) were used to inhibit the sarcolemmal Ca ATPase and Na/Ca exchanger (NCX) respectively. Carboxyeosin decreased the rate constant of decay of the caffeine-induced Ca transient in control cells, but had no effect in detubulated cells, suggesting that Ca extrusion via the Ca ATPase occurs only across the t-tubule membrane. However nickel decreased the rate constant of the caffeine-induced Ca transient in control and detubulated cells, although its effect was greater in control cells, suggesting that Ca extrusion via NCX occurs across the surface and t-tubule membranes. The PKA inhibitor H-89 (10 μmol/L) was used to investigate the role of basal PKA activity in Ca extrusion; H-89 appeared to have no effect on Ca extrusion via the Ca ATPase, but reduced Ca extrusion via NCX at the t-tubules but not the surface membrane. Thus it appears that Ca extrusion via the sarcolemmal Ca ATPase occurs only at the t-tubules, and is not regulated by basal PKA activity, while Ca extrusion via NCX occurs across both the surface and t-tubule membranes, but predominantly across the t-tubule membrane due, in part, to localised stimulation of NCX by PKA at the t-tubules. This may be important in heart disease, in which changes in t-tubule structure and protein phosphorylation occur.
    MeSH term(s) Animals ; Calcium/metabolism ; Calcium-Transporting ATPases/metabolism ; Cytoplasm/metabolism ; Heart Ventricles/cytology ; Isoproterenol/pharmacology ; Isoquinolines/pharmacology ; Male ; Myocytes, Cardiac/enzymology ; Myocytes, Cardiac/metabolism ; Protein Kinase Inhibitors/pharmacology ; Rats ; Sarcolemma/enzymology ; Sulfonamides/pharmacology
    Chemical Substances Isoquinolines ; Protein Kinase Inhibitors ; Sulfonamides ; Calcium-Transporting ATPases (EC 7.2.2.10) ; Isoproterenol (L628TT009W) ; N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide (M876330O56) ; Calcium (SY7Q814VUP)
    Language English
    Publishing date 2010-10-21
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 80157-4
    ISSN 1095-8584 ; 0022-2828
    ISSN (online) 1095-8584
    ISSN 0022-2828
    DOI 10.1016/j.yjmcc.2010.10.012
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Effect of Ca2+ Efflux Pathway Distribution and Exogenous Ca2+ Buffers on Intracellular Ca2+ Dynamics in the Rat Ventricular Myocyte

    Michal Pásek / Jiří Šimurda / Clive H. Orchard

    BioMed Research International, Vol

    A Simulation Study

    2014  Volume 2014

    Abstract: We have used a previously published computer model of the rat cardiac ventricular myocyte to investigate the effect of changing the distribution of Ca2+ efflux pathways (SERCA, Na+/Ca2+ exchange, and sarcolemmal Ca2+ ATPase) between the dyad and bulk ... ...

    Abstract We have used a previously published computer model of the rat cardiac ventricular myocyte to investigate the effect of changing the distribution of Ca2+ efflux pathways (SERCA, Na+/Ca2+ exchange, and sarcolemmal Ca2+ ATPase) between the dyad and bulk cytoplasm and the effect of adding exogenous Ca2+ buffers (BAPTA or EGTA), which are used experimentally to differentially buffer Ca2+ in the dyad and bulk cytoplasm, on cellular Ca2+ cycling. Increasing the dyadic fraction of a particular Ca2+ efflux pathway increases the amount of Ca2+ removed by that pathway, with corresponding changes in Ca2+ efflux from the bulk cytoplasm. The magnitude of these effects varies with the proportion of the total Ca2+ removed from the cytoplasm by that pathway. Differences in the response to EGTA and BAPTA, including changes in Ca2+-dependent inactivation of the L-type Ca2+ current, resulted from the buffers acting as slow and fast “shuttles,” respectively, removing Ca2+ from the dyadic space. The data suggest that complex changes in dyadic Ca2+ and cellular Ca2+ cycling occur as a result of changes in the location of Ca2+ removal pathways or the presence of exogenous Ca2+ buffers, although changing the distribution of Ca2+ efflux pathways has relatively small effects on the systolic Ca2+ transient.
    Keywords Medicine ; R
    Subject code 570
    Language English
    Publishing date 2014-01-01T00:00:00Z
    Publisher Hindawi Limited
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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