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Sample records for cardiac myocytes integrative

  1. Regulation of excitation-contraction coupling in mouse cardiac myocytes: integrative analysis with mathematical modelling

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    Weckström Matti

    2009-08-01

    normal and defective cellular physiology. We propose that integrative modelling as in the present work is a valuable complement to experiments in understanding the causality within complex biological systems such as cardiac myocytes.

  2. Towards an integrative computational model of the guinea pig cardiac myocyte

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    Laura Doyle Gauthier

    2012-07-01

    Full Text Available The local control theory of excitation-contraction (EC coupling asserts that regulation of calcium (Ca2+ release occurs at the nanodomain level, where openings of single L-type Ca2+ channels (LCCs trigger openings of small clusters of ryanodine receptors (RyRs co-localized within the dyad. A consequence of local control is that the whole-cell Ca2+ transient is a smooth continuous function of influx of Ca2+ through LCCs. While this so-called graded release property has been known for some time, it’s functional importance to the integrated behavior of the cardiac ventricular myocyte has not been fully appreciated. We previously formulated a biophysically-based model, in which LCCs and RyRs interact via a coarse-grained representation of the dyadic space. The model captures key features of local control using a low-dimensional system of ordinary differential equations. Voltage-dependent gain and graded Ca2+ release are emergent properties of this model by virtue of the fact that model formulation is closely based on the sub-cellular basis of local control. In this current work, we have incorporated this graded release model into a prior model of guinea pig ventricular myocyte electrophysiology, metabolism, and isometric force production. The resulting integrative model predicts the experimentally-observed causal relationship between action potential (AP shape and timing of Ca2+ and force transients, a relationship that is not explained by models lacking the graded release property. Model results suggest that even relatively subtle changes in AP morphology that may result, for example, from remodeling of membrane transporter expression in disease or spatial variation in cell properties, may have major impact on the temporal waveform of Ca2+ transients, thus influencing tissue-level electro-mechanical function.

  3. β-adrenergic effects on cardiac myofilaments and contraction in an integrated rabbit ventricular myocyte model.

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    Negroni, Jorge A; Morotti, Stefano; Lascano, Elena C; Gomes, Aldrin V; Grandi, Eleonora; Puglisi, José L; Bers, Donald M

    2015-04-01

    A five-state model of myofilament contraction was integrated into a well-established rabbit ventricular myocyte model of ion channels, Ca(2+) transporters and kinase signaling to analyze the relative contribution of different phosphorylation targets to the overall mechanical response driven by β-adrenergic stimulation (β-AS). β-AS effect on sarcoplasmic reticulum Ca(2+) handling, Ca(2+), K(+) and Cl(-) currents, and Na(+)/K(+)-ATPase properties was included based on experimental data. The inotropic effect on the myofilaments was represented as reduced myofilament Ca(2+) sensitivity (XBCa) and titin stiffness, and increased cross-bridge (XB) cycling rate (XBcy). Assuming independent roles of XBCa and XBcy, the model reproduced experimental β-AS responses on action potentials and Ca(2+) transient amplitude and kinetics. It also replicated the behavior of force-Ca(2+), release-restretch, length-step, stiffness-frequency and force-velocity relationships, and increased force and shortening in isometric and isotonic twitch contractions. The β-AS effect was then switched off from individual targets to analyze their relative impact on contractility. Preventing β-AS effects on L-type Ca(2+) channels or phospholamban limited Ca(2+) transients and contractile responses in parallel, while blocking phospholemman and K(+) channel (IKs) effects enhanced Ca(2+) and inotropy. Removal of β-AS effects from XBCa enhanced contractile force while decreasing peak Ca(2+) (due to greater Ca(2+) buffering), but had less effect on shortening. Conversely, preventing β-AS effects on XBcy preserved Ca(2+) transient effects, but blunted inotropy (both isometric force and especially shortening). Removal of titin effects had little impact on contraction. Finally, exclusion of β-AS from XBCa and XBcy while preserving effects on other targets resulted in preserved peak isometric force response (with slower kinetics) but nearly abolished enhanced shortening. β-AS effects on XBCa and XBcy

  4. Phosphatidylinositol-bisphosphate regulates intercellular coupling in cardiac myocytes

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    Hofgaard, Johannes P; Banach, Kathrin; Mollerup, Sarah

    2008-01-01

    Changes in the lipid composition of cardiac myocytes have been reported during cardiac hypertrophy, cardiomyopathy, and infarction. Because a recent study indicates a relation between low phosphatidylinositol-bisphosphate (PIP(2)) levels and reduced intercellular coupling, we tested the hypothesi...

  5. Microfluidic partitioning of the extracellular space around single cardiac myocytes.

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    Klauke, Norbert; Smith, Godfrey L; Cooper, Jonathan M

    2007-02-01

    This paper describes the partitioning of the extracellular space around an electrically activated single cardiac myocyte, constrained within a microfluidic device. Central to this new method is the production of a hydrophobic gap-structure, which divides the extracellular space into two distinct microfluidic pools. The content of these pools was controlled using a pair of concentric automated pipets (subsequently called "dual superfusion pipet"), each providing the ability to dispense (i.e., the source, inner pipet) and aspirate (the sink, outer pipet) a buffer solution (perfusate) into each of the two pools. For rapid solution switching around the cell, additional dual superfusion pipets were inserted into the microchannel for defined time periods using a piezostepper, enabling us to add a test solution, such as a drug. Three distinct areas of the cell were manipulated, namely, the microfluidic environment, the cellular membrane, and the intracellular space. Planar integrated microelectrodes enabled the electrical stimulation of the cardiomyocyte and the recording of the evoked action potential. The device was mounted on an inverted microscope to allow simultaneous sarcomere length and epifluorescence measurements during evoked electrical activity, including, for example, the response of the stimulated end of the cardiac myocyte in comparison with the untreated cell end.

  6. Sensing Cardiac Electrical Activity With a Cardiac Myocyte--Targeted Optogenetic Voltage Indicator

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    Chang Liao, Mei-Ling; de Boer, Teun P; Mutoh, Hiroki; Raad, Nour; Richter, Claudia; Wagner, Eva; Downie, Bryan R; Unsöld, Bernhard; Arooj, Iqra; Streckfuss-Bömeke, Katrin; Döker, Stephan; Luther, Stefan; Guan, Kaomei; Wagner, Stefan; Lehnart, Stephan E; Maier, Lars S; Stühmer, Walter; Wettwer, Erich; van Veen, Toon; Morlock, Michael M; Knöpfel, Thomas; Zimmermann, Wolfram-Hubertus

    2015-01-01

    RATIONALE: Monitoring and controlling cardiac myocyte activity with optogenetic tools offer exciting possibilities for fundamental and translational cardiovascular research. Genetically encoded voltage indicators may be particularly attractive for minimal invasive and repeated assessments of cardiac

  7. Salvianolic acid B inhibits autophagy and protects starving cardiac myocytes

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    Han, Xiao; Liu, Jian-Xun; Xin-zhi LI

    2010-01-01

    Aim: To investigate the protective or lethal role of autophagy and the effects of Salvianolic acid B (Sal B) on autophagy in starving myocytes. Methods: Cardiac myocytes were incubated under starvation conditions (GD) for 0, 1, 2, 3, and 6 h. Autophagic flux in starving cells was measured via chloroquine (3 μmol/L). After myocytes were treated with Sal B (50 μmol/L) in the presence or absence of chloroquine (3 μmol/L) under GD 3 h, the amount of LC3-II, the abundance of LC3-positive fluoresce...

  8. The Frank-Starling mechanism in vertebrate cardiac myocytes.

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    Shiels, Holly A; White, Ed

    2008-07-01

    The Frank-Starling law of the heart applies to all classes of vertebrates. It describes how stretch of cardiac muscle, up to an optimum length, increases contractility thereby linking cardiac ejection to cardiac filling. The cellular mechanisms underlying the Frank-Starling response include an increase in myofilament sensitivity for Ca2+, decreased myofilament lattice spacing and increased thin filament cooperativity. Stretching of mammalian, amphibian and fish cardiac myocytes reveal that the functional peak of the sarcomere length (SL)-tension relationship occurs at longer SL in the non-mammalian classes. These findings correlate with in vivo cardiac function as non-mammalian vertebrates, such as fish, vary stroke volume to a relatively larger extent than mammals. Thus, it seems the length-dependent properties of individual myocytes are modified to accommodate differences in organ function, and the high extensibility of certain hearts is matched by the extensibility of their myocytes. Reasons for the differences between classes are still to be elucidated, however, the structure of mammalian ventricular myocytes, with larger widths and higher levels of passive stiffness than those from other vertebrate classes may be implicated.

  9. Nuclear morphology and deformation in engineered cardiac myocytes and tissues.

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    Bray, Mark-Anthony P; Adams, William J; Geisse, Nicholas A; Feinberg, Adam W; Sheehy, Sean P; Parker, Kevin K

    2010-07-01

    Cardiac tissue engineering requires finely-tuned manipulation of the extracellular matrix (ECM) microenvironment to optimize internal myocardial organization. The myocyte nucleus is mechanically connected to the cell membrane via cytoskeletal elements, making it a target for the cellular response to perturbation of the ECM. However, the role of ECM spatial configuration and myocyte shape on nuclear location and morphology is unknown. In this study, printed ECM proteins were used to configure the geometry of cultured neonatal rat ventricular myocytes. Engineered one- and two-dimensional tissue constructs and single myocyte islands were assayed using live fluorescence imaging to examine nuclear position, morphology and motion as a function of the imposed ECM geometry during diastolic relaxation and systolic contraction. Image analysis showed that anisotropic tissue constructs cultured on microfabricated ECM lines possessed a high degree of nuclear alignment similar to that found in vivo; nuclei in isotropic tissues were polymorphic in shape with an apparently random orientation. Nuclear eccentricity was also increased for the anisotropic tissues, suggesting that intracellular forces deform the nucleus as the cell is spatially confined. During systole, nuclei experienced increasing spatial confinement in magnitude and direction of displacement as tissue anisotropy increased, yielding anisotropic deformation. Thus, the nature of nuclear displacement and deformation during systole appears to rely on a combination of the passive myofibril spatial organization and the active stress fields induced by contraction. Such findings have implications in understanding the genomic consequences and functional response of cardiac myocytes to their ECM surroundings under conditions of disease.

  10. Cardiac myocyte exosomes: stability, HSP60, and proteomics.

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    Malik, Z A; Kott, K S; Poe, A J; Kuo, T; Chen, L; Ferrara, K W; Knowlton, A A

    2013-04-01

    Exosomes, which are 50- to 100-nm-diameter lipid vesicles, have been implicated in intercellular communication, including transmitting malignancy, and as a way for viral particles to evade detection while spreading to new cells. Previously, we demonstrated that adult cardiac myocytes release heat shock protein (HSP)60 in exosomes. Extracellular HSP60, when not in exosomes, causes cardiac myocyte apoptosis via the activation of Toll-like receptor 4. Thus, release of HSP60 from exosomes would be damaging to the surrounding cardiac myocytes. We hypothesized that 1) pathological changes in the environment, such as fever, change in pH, or ethanol consumption, would increase exosome permeability; 2) different exosome inducers would result in different exosomal protein content; 3) ethanol at "physiological" concentrations would cause exosome release; and 4) ROS production is an underlying mechanism of increased exosome production. We found the following: first, exosomes retained their protein cargo under different physiological/pathological conditions, based on Western blot analyses. Second, mass spectrometry demonstrated that the protein content of cardiac exosomes differed significantly from other types of exosomes in the literature and contained cytosolic, sarcomeric, and mitochondrial proteins. Third, ethanol did not affect exosome stability but greatly increased the production of exosomes by cardiac myocytes. Fourth, ethanol- and hypoxia/reoxygenation-derived exosomes had different protein content. Finally, ROS inhibition reduced exosome production but did not completely inhibit it. In conclusion, exosomal protein content is influenced by the cell source and stimulus for exosome formation. ROS stimulate exosome production. The functions of exosomes remain to be fully elucidated.

  11. Nanomaterials for Cardiac Myocyte Tissue Engineering

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    Rodolfo Amezcua

    2016-07-01

    Full Text Available Since their synthesizing introduction to the research community, nanomaterials have infiltrated almost every corner of science and engineering. Over the last decade, one such field has begun to look at using nanomaterials for beneficial applications in tissue engineering, specifically, cardiac tissue engineering. During a myocardial infarction, part of the cardiac muscle, or myocardium, is deprived of blood. Therefore, the lack of oxygen destroys cardiomyocytes, leaving dead tissue and possibly resulting in the development of arrhythmia, ventricular remodeling, and eventual heart failure. Scarred cardiac muscle results in heart failure for millions of heart attack survivors worldwide. Modern cardiac tissue engineering research has developed nanomaterial applications to combat heart failure, preserve normal heart tissue, and grow healthy myocardium around the infarcted area. This review will discuss the recent progress of nanomaterials for cardiovascular tissue engineering applications through three main nanomaterial approaches: scaffold designs, patches, and injectable materials.

  12. Maturation status of sarcomere structure and function in human iPSC-derived cardiac myocytes.

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    Bedada, Fikru B; Wheelwright, Matthew; Metzger, Joseph M

    2016-07-01

    Human heart failure due to myocardial infarction is a major health concern. The paucity of organs for transplantation limits curative approaches for the diseased and failing adult heart. Human induced pluripotent stem cell-derived cardiac myocytes (hiPSC-CMs) have the potential to provide a long-term, viable, regenerative-medicine alternative. Significant progress has been made with regard to efficient cardiac myocyte generation from hiPSCs. However, directing hiPSC-CMs to acquire the physiological structure, gene expression profile and function akin to mature cardiac tissue remains a major obstacle. Thus, hiPSC-CMs have several hurdles to overcome before they find their way into translational medicine. In this review, we address the progress that has been made, the void in knowledge and the challenges that remain. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.

  13. Improving cardiac myocytes performance by CNTs platforms

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    Valentina eMartinelli

    2013-09-01

    Full Text Available The application of nanotechnology to the cardiovascular system has increasingly caught scientists’ attention as a potentially powerful tool for the development of new generation devices able to interface, repair or boost the performance of cardiac tissue. Carbon nanotubes (CNTs are considered as promising materials for nanomedicine applications in general and have been recently tested towards excitable cell growth. CNTs are cylindrically shaped structures made up of rolled-up graphene sheets, with unique electrical, thermal and mechanical properties, able to effectively conducting electrical current in electrochemical interfaces. CNTs-based scaffolds have been recently found to support the in vitro growth of cardiac cells: in particular, their ability to improve cardiomyocytes proliferation, maturation and electrical behavior are making CNTs extremely attractive for the development and exploitation of interfaces able to impact on cardiac cells physiology and function.

  14. Salvianolic acid B inhibits autophagy and protects starving cardiac myocytes

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    Han, Xiao; Liu, Jian-xun; Li, Xin-zhi

    2011-01-01

    Aim: To investigate the protective or lethal role of autophagy and the effects of Salvianolic acid B (Sal B) on autophagy in starving myocytes. Methods: Cardiac myocytes were incubated under starvation conditions (GD) for 0, 1, 2, 3, and 6 h. Autophagic flux in starving cells was measured via chloroquine (3 μmol/L). After myocytes were treated with Sal B (50 μmol/L) in the presence or absence of chloroquine (3 μmol/L) under GD 3 h, the amount of LC3-II, the abundance of LC3-positive fluorescent dots in cells, cell viability and cellular ATP levels were determined using immunoblotting, immunofluorescence microscopy, MTT assay and luminometer, respectively. Moreover, electron microscopy (EM) and immunofluorescent duel labeling of LC3 and Caspase-8 were used to examine the characteristics of autophagy and apoptosis. Results: Immunoblot analysis showed that the amount of LC3-II in starving cells increased in a time-dependent manner accompanied by increased LC3-positive fluorescence and decreased cell viability and ATP content. Sal B (50 μmol/L) inhibited the increase in LC3-II, reduced the abundance of LC3 immunofluorescence and intensity of Caspase-8 fluorescence, and enhanced cellular viability and ATP levels in myocytes under GD 3 h, regardless of whether chloroquine was present. Conclusion: Autophagy induced by starvation for 3 h led to cell injury. Sal B protected starving cells by blocking the early stage of autophagic flux and inhibiting apoptosis that occurred during autophagy. PMID:21113177

  15. Isoprenaline enhances local Ca2+ release in cardiac myocytes

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    Jian-xin SHEN

    2006-01-01

    Aim: Contraction of cardiac myocytes is controlled by the generation and amplification of intracellular Ca2+ signals. The key step of this process is the coupling between sarcolemma L-type Ca2+ channels (LCCs) and ryanodine receptors (RyRs) in the sarcoplasmic reticulum (SR). β-Adrenergic stimulation is an important regulatory mechanism for this coupling process. But the details underlied the global level, which require local Ca2+ release study are still unclear. The present study is to explore the effects of β-adrenergic stimulation on local Ca2+ release. Methods: Using confocal microscopy combined with loose-seal patch-clamp approaches, effects of isoprenaline (1 μmol·L-1), a β-adrenergic agonist, on local SR Ca2+ release triggered by Ca2+ influx through LCCs in intact rat cardiac myocytes were investigated. Results: Isoprenaline increased the intensity of ensemble averaged local Ca2+ transients, the peak of which displayed a typical bell-shaped voltage-dependence over the membrane voltages ranging from ~-40mV to ~+35mV. Further analysis showed that this enhancement could be explained by the increased coupling fidelity (which refers the increased probability of RyRs activation upon depolarization), and the increased amplitude of evoked Ca2+ sparks (due to more Ca2+ releases through local RyRs). In addition, isoprenaline decreased the first latency, which displayed a typical "U"-shaped voltage-dependence, showing the available acceleration and synchronization of β-adrenergic stimulation on intracellular calcium release. Conclusions: Isoprenaline enhances local Ca2+ release in cardiac myocytes. These results underscore the importance of regulation of β-adrenergic stimulation on local intermolecular signals between LCCs and RyRs in heart cells.

  16. Isolation of cardiac myocytes and fibroblasts from neonatal rat pups.

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    Golden, Honey B; Gollapudi, Deepika; Gerilechaogetu, Fnu; Li, Jieli; Cristales, Ricardo J; Peng, Xu; Dostal, David E

    2012-01-01

    Neonatal rat ventricular myocytes (NRVM) and fibroblasts (FBs) serve as in vitro models for studying fundamental mechanisms underlying cardiac pathologies, as well as identifying potential therapeutic targets. Both cell types are relatively easy to culture as monolayers and can be manipulated using molecular and pharmacological tools. Because NRVM cease to proliferate after birth, and FBs undergo phenotypic changes and senescence after a few passages in tissue culture, primary cultures of both cell types are required for experiments. Below we describe methods that provide good cell yield and viability of primary cultures of NRVM and FBs from 0 to 3-day-old neonatal rat pups.

  17. Salvianolic acid B inhibits autophagy and protects starving cardiac myocytes

    Institute of Scientific and Technical Information of China (English)

    Xiao HAN; Jian-xun LIU; Xin-zhi LI

    2011-01-01

    Aim: To investigate the protective or lethal role of autophagy and the effects of Salvianolic acid B (Sal B) on autophagy in starving myocytes.Methods: Cardiac myocytes were incubated under starvation conditions (GD) for O, 1, 2, 3, and 6 h. Autophagic flux in starving cells was measured via chloroquine (3 μmol/L). After myocytes were treated with Sat B (50 μmol/L) in the presence or absence of chloro-quine (3 μmol/L) under GD 3 h, the amount of LC3-11, the abundance of LC3-positive fluorescent dots in cells, cell viability and cellular ATP levels were determined using immunoblotting, immunofluorescence microscopy, MTT assay and luminometer, respectively. More-over, electron microscopy (EM) and immunofluorescent duel labeling of LC3 and Caspase-8 were used to examine the characteristics of autophagy and apoptosis.Results: Immunoblot analysis showed that the amount of LC3-11 in starving cells increased in a time-dependent manner accompanied by increased LC3-positive fluorescence and decreased cell viability and ATP content. Sal B (50 μmol/L) inhibited the increase in LC3-11, reduced the abundance of LC3 immunofluorescence and intensity of Caspase-8 fluorescence, and enhanced cellular viability and ATP levels in myocytes under GD 3 h, regardless of whether chloroquine was present.Conclusion: Autophagy induced by starvation for 3 h led to cell injury. Sal B protected starving cells by blocking the early stage of autophagic flux and inhibiting apoptosis that occurred during autophagy.

  18. Magnesium homeostasis in cardiac myocytes of Mg-deficient rats.

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    Michiko Tashiro

    Full Text Available To study possible modulation of Mg(2+ transport in low Mg(2+ conditions, we fed either a Mg-deficient diet or a Mg-containing diet (control to Wistar rats for 1-6 weeks. Total Mg concentrations in serum and cardiac ventricular tissues were measured by atomic absorption spectroscopy. Intracellular free Mg(2+ concentration ([Mg(2+]i of ventricular myocytes was measured with the fluorescent indicator furaptra. Mg(2+ transport rates, rates of Mg(2+ influx and Mg(2+ efflux, were estimated from the rates of change in [Mg(2+]i during Mg loading/depletion and recovery procedures. In Mg-deficient rats, the serum total Mg concentration (0.29±0.026 mM was significantly lower than in control rats (0.86±0.072 mM after 4-6 weeks of Mg deficiency. However, neither total Mg concentration in ventricular tissues nor [Mg(2+]i of ventricular myocytes was significantly different between Mg-deficient rats and control rats. The rates of Mg(2+ influx and efflux were not significantly different in both groups. In addition, quantitative RT-PCR revealed that Mg deficiency did not substantially change mRNA expression levels of known Mg(2+ channels/transporters (TRPM6, TRPM7, MagT1, SLC41A1 and ACDP2 in heart and kidney tissues. These results suggest that [Mg(2+]i as well as the total Mg content of cardiac myocytes, was well maintained even under chronic hypomagnesemia without persistent modulation in function and expression of major Mg(2+ channels/transporters in the heart.

  19. The timing statistics of spontaneous calcium release in cardiac myocytes.

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    Mesfin Asfaw

    Full Text Available A variety of cardiac arrhythmias are initiated by a focal excitation that disrupts the regular beating of the heart. In some cases it is known that these excitations are due to calcium (Ca release from the sarcoplasmic reticulum (SR via propagating subcellular Ca waves. However, it is not understood what are the physiological factors that determine the timing of these excitations at both the subcellular and tissue level. In this paper we apply analytic and numerical approaches to determine the timing statistics of spontaneous Ca release (SCR in a simplified model of a cardiac myocyte. In particular, we compute the mean first passage time (MFPT to SCR, in the case where SCR is initiated by spontaneous Ca sparks, and demonstrate that this quantity exhibits either an algebraic or exponential dependence on system parameters. Based on this analysis we identify the necessary requirements so that SCR occurs on a time scale comparable to the cardiac cycle. Finally, we study how SCR is synchronized across many cells in cardiac tissue, and identify a quantitative measure that determines the relative timing of SCR in an ensemble of cells. Using this approach we identify the physiological conditions so that cell-to-cell variations in the timing of SCR is small compared to the typical duration of an SCR event. We argue further that under these conditions inward currents due to SCR can summate and generate arrhythmogenic triggered excitations in cardiac tissue.

  20. Mitochondria-Targeted Antioxidant Prevents Cardiac Dysfunction Induced by Tafazzin Gene Knockdown in Cardiac Myocytes

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    Quan He

    2014-01-01

    Full Text Available Tafazzin, a mitochondrial acyltransferase, plays an important role in cardiolipin side chain remodeling. Previous studies have shown that dysfunction of tafazzin reduces cardiolipin content, impairs mitochondrial function, and causes dilated cardiomyopathy in Barth syndrome. Reactive oxygen species (ROS have been implicated in the development of cardiomyopathy and are also the obligated byproducts of mitochondria. We hypothesized that tafazzin knockdown increases ROS production from mitochondria, and a mitochondria-targeted antioxidant prevents tafazzin knockdown induced mitochondrial and cardiac dysfunction. We employed cardiac myocytes transduced with an adenovirus containing tafazzin shRNA as a model to investigate the effects of the mitochondrial antioxidant, mito-Tempo. Knocking down tafazzin decreased steady state levels of cardiolipin and increased mitochondrial ROS. Treatment of cardiac myocytes with mito-Tempo normalized tafazzin knockdown enhanced mitochondrial ROS production and cellular ATP decline. Mito-Tempo also significantly abrogated tafazzin knockdown induced cardiac hypertrophy, contractile dysfunction, and cell death. We conclude that mitochondria-targeted antioxidant prevents cardiac dysfunction induced by tafazzin gene knockdown in cardiac myocytes and suggest mito-Tempo as a potential therapeutic for Barth syndrome and other dilated cardiomyopathies resulting from mitochondrial oxidative stress.

  1. De Novo Human Cardiac Myocytes for Medical Research: Promises and Challenges

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    Hamel, Veronique; Cheng, Kang; Liao, Shudan; Lu, Aizhu; Zheng, Yong; Chen, Yawen; Xie, Yucai

    2017-01-01

    The advent of cellular reprogramming technology has revolutionized biomedical research. De novo human cardiac myocytes can now be obtained from direct reprogramming of somatic cells (such as fibroblasts), from induced pluripotent stem cells (iPSCs, which are reprogrammed from somatic cells), and from human embryonic stem cells (hESCs). Such de novo human cardiac myocytes hold great promise for in vitro disease modeling and drug screening and in vivo cell therapy of heart disease. Here, we review the technique advancements for generating de novo human cardiac myocytes. We also discuss several challenges for the use of such cells in research and regenerative medicine, such as the immature phenotype and heterogeneity of de novo cardiac myocytes obtained with existing protocols. We focus on the recent advancements in addressing such challenges.

  2. Stochastic Alternating Dynamics for Synchronous EAD-Like Beating Rhythms in Cultured Cardiac Myocytes

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    ZHANG Ning; ZHANG Hui-Min; LIU Zhi-Qiang; DING Xue-Li; YANG Ming-Hao; GU Hua-Guang; REN Wei

    2009-01-01

    Dissolved cardiac myocytes can couple together and generate synchronous beatings in culture. We observed a synchronized early after-depolarization(EAD)-like rhythm in cultured cardiac myocytes and reproduced the experimental observation in a network mathematical model whose dynamics are close to a Hopf bifurcation. The mechanism for this EAD-like rhythm is attributed to noised-induced stochastic alternatings between the focus and the limit cycle. These results provide novel understandings for pathological heart rhythms like the early immature beatings.

  3. Finite element model to study two dimensional unsteady state calcium distribution in cardiac myocytes

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    Kunal Pathak

    2016-09-01

    Full Text Available The calcium signaling plays a crucial role in expansion and contraction of cardiac myocytes. This calcium signaling is achieved by calcium diffusion, buffering mechanisms and influx in cardiac myocytes. The various calcium distribution patterns required for achieving calcium signaling in myocytes are still not well understood. In this paper an attempt has been made to develop a model of calcium distribution in myocytes incorporating diffusion of calcium, point source and excess buffer approximation. The model has been developed for a two dimensional unsteady state case. Appropriate boundary conditions and initial condition have been framed. The finite element method has been employed to obtain the solution. The numerical results have been used to study the effect of buffers and source amplitude on calcium distribution in myocytes.

  4. Regulation of cardiac myocyte contractility by phospholemman: Na+/Ca2+ exchange versus Na+ -K+ -ATPase.

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    Song, Jianliang; Zhang, Xue-Qian; Wang, JuFang; Cheskis, Ellina; Chan, Tung O; Feldman, Arthur M; Tucker, Amy L; Cheung, Joseph Y

    2008-10-01

    Phospholemman (PLM) regulates cardiac Na(+)/Ca(2+) exchanger (NCX1) and Na(+)-K(+)-ATPase in cardiac myocytes. PLM, when phosphorylated at Ser(68), disinhibits Na(+)-K(+)-ATPase but inhibits NCX1. PLM regulates cardiac contractility by modulating Na(+)-K(+)-ATPase and/or NCX1. In this study, we first demonstrated that adult mouse cardiac myocytes cultured for 48 h had normal surface membrane areas, t-tubules, and NCX1 and sarco(endo)plasmic reticulum Ca(2+)-ATPase levels, and retained near normal contractility, but alpha(1)-subunit of Na(+)-K(+)-ATPase was slightly decreased. Differences in contractility between myocytes isolated from wild-type (WT) and PLM knockout (KO) hearts were preserved after 48 h of culture. Infection with adenovirus expressing green fluorescent protein (GFP) did not affect contractility at 48 h. When WT PLM was overexpressed in PLM KO myocytes, contractility and cytosolic Ca(2+) concentration ([Ca(2+)](i)) transients reverted back to those observed in cultured WT myocytes. Both Na(+)-K(+)-ATPase current (I(pump)) and Na(+)/Ca(2+) exchange current (I(NaCa)) in PLM KO myocytes rescued with WT PLM were depressed compared with PLM KO myocytes. Overexpressing the PLMS68E mutant (phosphomimetic) in PLM KO myocytes resulted in the suppression of I(NaCa) but had no effect on I(pump). Contractility, [Ca(2+)](i) transient amplitudes, and sarcoplasmic reticulum Ca(2+) contents in PLM KO myocytes overexpressing the PLMS68E mutant were depressed compared with PLM KO myocytes overexpressing GFP. Overexpressing the PLMS68A mutant (mimicking unphosphorylated PLM) in PLM KO myocytes had no effect on I(NaCa) but decreased I(pump). Contractility, [Ca(2+)](i) transient amplitudes, and sarcoplasmic reticulum Ca(2+) contents in PLM KO myocytes overexpressing the S68A mutant were similar to PLM KO myocytes overexpressing GFP. We conclude that at the single-myocyte level, PLM affects cardiac contractility and [Ca(2+)](i) homeostasis primarily by its direct

  5. Construction of calcium release sites in cardiac myocytes

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    Alexandra eZahradnikova

    2012-08-01

    Full Text Available Local character of calcium release in cardiac myocytes, as defined by confocal recordings of calcium sparks, implies independent activation of individual calcium release sites based on ryanodine receptor (RyR channel recruitment. We constructed virtual calcium release sites (vCRSs composed of a variable number of RyR channels distributed in clusters in accordance with the experimentally observed cluster size distribution. The vCRSs consisted either of a single virtual calcium release unit, in which all clusters shared a common dyadic space, or of multiple virtual calcium release units containing one cluster each and having separate dyadic spaces. We explored the stochastic behavior of vCRSs to understand the activation and recruitment of RyRs during calcium sparks. RyRs were represented by the published allosteric gating model that included regulation by cytosolic Ca2+ and Mg2+. The interaction of Mg2+ with the RyR Ca2+-binding sites and the refractory period of vCRSs were optimized to accord with the experimentally observed calcium dependence of calcium spark frequency. The Mg2+-binding parameters of RyRs that provided the best description of spark frequency depended on the number of RyRs assembled in the virtual calcium release sites. Adequate inhibitory effect of Mg2+ on the calcium dependence of RyR open probability was achieved if the virtual calcium release sites contained at least three clusters. For the distribution of the number of open RyRs in evoked calcium sparks to correspond to the experimentally observed distribution of spark calcium release fluxes, at least 3 clusters had to share a common virtual calcium release unit, in which ~ 3 RyRs open to form an average spark. These results reconcile the small cluster size and stochastic placement of RyRs in the release sites with the estimates of the amount of RyR protein, volume density of calcium release sites, and the size of calcium release sites in rat cardiac myocytes.

  6. VAMP-1, VAMP-2, and syntaxin-4 regulate ANP release from cardiac myocytes.

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    Ferlito, Marcella; Fulton, William B; Zauher, Mohamed A; Marbán, Eduardo; Steenbergen, Charles; Lowenstein, Charles J

    2010-11-01

    ANP is a peptide released by cardiac myocytes that regulates blood pressure and natriuresis. However, the molecular mechanisms controlling ANP release from cardiac myocytes are not defined. We now identify three components of the exocytic machinery that regulate ANP release from atrial myocytes. We found that cardiac myocytes express N-ethylmaleimide sensitive factor (NSF), soluble NSF attachment protein (α-SNAP), and SNAP receptors (SNAREs). Additionally we found that specific SNARE molecules, VAMP-1 and VAMP-2, both co-sediment and co-localize with ANP. Also, one SNARE molecule, syntaxin-4, partially co-sediments and partially co-localizes with ANP. Furthermore, these three SNAREs, syntaxin-4 and VAMP-1 and VAMP-2, form a SNARE complex inside cardiac myocytes. Finally, knockdown of VAMP-1, VAMP-2, or syntaxin-4 blocks regulated release of ANP. In contrast, silencing of VAMP-3 did not have an effect on ANP release. Our data suggest that three specific SNAREs regulate cardiac myocyte exocytosis of ANP. Pathways that modify the exocytic machinery may influence natriuresis and blood pressure.

  7. Calcium binding to cardiac myocytes protected from proteolytic enzyme activity.

    Science.gov (United States)

    Bailey, L E; Fawzi, A B

    1985-04-17

    Excitation-contraction coupling in cardiac muscle is dependent on extracellular calcium and calcium bound to the surface of the myocardial cell. In this study, we examined the physical characteristics of calcium binding to adult guinea pig ventricular myocytes disaggregated mechanically in oxygenated tissue culture medium containing a proteinase inhibitor (aprotinin), and separated from cellular debris by Cytodex beads. Cells prepared in this manner excluded Trypan blue and showed no evidence of spontaneous contraction or contracture. Scatchard plots of calcium binding determined by continuous flow equilibrium dialysis revealed a high-affinity, low-capacity pool, Ka = 65 X 10(3) M-1 and Bt = 1.3 nmol X mg-1 and a low-affinity, high-capacity pool, Ka = 141 M-1 and Bt = 138 nmol X mg-1. The low-affinity pool was not detectable after lanthanum, trypsin or collagenase treatment or in cells prepared without aprotinin in the isolation medium. Both neuraminidase and phospholipase C reduced Bt of the low-affinity pool by one half, but only neuraminidase affected the affinity constant of this pool. Ka was increased to 516.7 M-1, similar to the apparent affinity constant for calcium binding estimated from dP/dtmax measured at several extracellular calcium concentrations (470 M-1). The results suggest that calcium bound to sarcolemmal phospholipids represents the superficial calcium involved in excitation-contraction coupling in the heart.

  8. Antioxidant Effect of Human Selenium-containing Single-chain Fv in Rat Cardiac Myocytes

    Institute of Scientific and Technical Information of China (English)

    HUO Rui; SHI Yi; XU Jun-jie; YAN Fei; L(U) Shao-wu; SU Jia-ming; DUAN Yu-jing; FAN Jia; NING Bo; CONG Deng-li; YAN Gang-lin; LUO Gui-min; WEI Jing-yan

    2009-01-01

    Reactive oxygen species(ROS) plays a key role in human heart diseases.Glutathione peroxidase(GPX) functions as an antioxidant as it catalyzes the reduction of hydroperoxide.In order to investigate the antioxidant effect of human selenium-containing single-chain Fv(Se-scFv-B3),a new mimic of GPX,a model system of hydrogen peroxide(H2O2)-induced rat cardiac myocyte damage was established.The cardiac myocyte damage was characterized in terms of cell viability,lipid peroxidation,cell membrane integrity,and intracellular H2O2 level.The Se-scFv-B3 significantly reduced H2O2-induced cell damage as shown by the increase of cell viability,the decline of malondialdehyde(MDA) production,lactate dehydrogenase(LDH) release,and intracellular H2O2 level.So Se-scFvB3 may have a great potential in the treatment of human heart diseases induced by ROS.

  9. Cellular redox status determines sensitivity to BNIP3-mediated cell death in cardiac myocytes

    OpenAIRE

    Lee, Youngil; Kubli, Dieter A.; Hanna, Rita A.; Cortez, Melissa Q.; Lee, Hwa-Youn; Miyamoto, Shigeki; Gustafsson, Åsa B.

    2015-01-01

    The atypical BH3-only protein Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (BNIP3) is an important regulator of hypoxia-mediated cell death. Interestingly, the susceptibility to BNIP3-mediated cell death differs between cells. In this study we examined whether there are mechanistic differences in BNIP3-mediated cell death between neonatal and adult cardiac myocytes. We discovered that BNIP3 is a potent inducer of cell death in neonatal myocytes, whereas adult myocytes are remarkably resi...

  10. Hyperplasia of myocyte nuclei in long-term cardiac hypertrophy in rats.

    OpenAIRE

    Olivetti, G; R. Ricci; Anversa, P.

    1987-01-01

    In contrast to observations made in the human heart, hyperplasia of myocyte nuclei has never been demonstrated in experimental cardiac hypertrophy. To test the hypothesis that the duration of the mechanical load more than the magnitude of ventricular hypertrophy may be the inciting stimulus for myocyte nuclei hyperplasia, constriction of the pulmonary artery was produced in rats and the hearts were examined 6 mo later. A 76% increase in right ventricular weight was measured. This hypertrophic...

  11. Cardiac Hypertrophy Involves both Myocyte Hypertrophy and Hyperplasia in Anemic Zebrafish

    OpenAIRE

    Xiaojing Sun; Tiffany Hoage; Ping Bai; Yonghe Ding; Zhenyue Chen; Ruilin Zhang; Wei Huang; Ashad Jahangir; Barry Paw; Yi-Gang Li; Xiaolei Xu

    2009-01-01

    BACKGROUND: An adult zebrafish heart possesses a high capacity of regeneration. However, it has been unclear whether and how myocyte hyperplasia contributes to cardiac remodeling in response to biomechanical stress and whether myocyte hypertrophy exists in the zebrafish. To address these questions, we characterized the zebrafish mutant tr265/tr265, whose Band 3 mutation disrupts erythrocyte formation and results in anemia. Although Band 3 does not express and function in the heart, the chroni...

  12. Protective function of tocilizumab in human cardiac myocytes ischemia reperfusion injury

    Institute of Scientific and Technical Information of China (English)

    Hai-Feng Cheng; Yan Feng; Da-Ming Jiang; Kai-Yu Tao; Min-Jian Kong

    2015-01-01

    Objective:To investigate the protective function of tocilizumab in human cardiac myocytes ischemia-reperfusion injury.Methods:The human cardiac myocytes were treated by tocilizumab with different concentrations(1.0 mg/mL, 3.0 mg/mL, 5.0 mg/mL) for 24 h,then cells were cultured in ischemia environment for 24 h and reperfusion environment for 1 h. The MTT and flow cytometry were used to detect the proliferation and apoptosis of human cardiac myocytes, respectively. The mRNA and protein expressions of Bcl-2 and Bax were measured by qRT-PCR and western blot, respectively.Results:Compared to the negative group, pretreated by tocilizumab could significantly enhance the proliferation viability and suppress apoptosis of human cardiac myocytes after suffering ischemia reperfusion injury(P<0.05).The expression of Bcl-2 in tocilizumab treated group were higher thanNC group(P<0.05), while theBax expression were lower(P<0.05).Conclusions:Tocilizumab could significantly inhibit apoptosis and keep the proliferation viability of human cardiac myocytes after suffering ischemia reperfusion injury. Tocilizumab may obtain a widely application in the protection of ischemia reperfusion injury.

  13. Novel Protective Role of Endogenous Cardiac Myocyte P2X4 Receptors in Heart Failure

    Science.gov (United States)

    Yang, Tiehong; Shen, Jian-bing; Yang, Ronghua; Redden, John; Dodge-Kafka, Kimberly; Grady, James; Jacobson, Kenneth A.; Liang, Bruce T.

    2014-01-01

    Background Heart failure (HF), despite continuing progress, remains a leading cause of mortality and morbidity. P2X4 receptors (P2X4R) have emerged as potentially important molecules in regulating cardiac function and as potential targets for HF therapy. Transgenic P2X4R overexpression can protect against HF, but this does not explain the role of native cardiac P2X4R. Our goal is to define the physiological role of endogenous cardiac myocyte P2X4R under basal conditions and during HF induced by myocardial infarction or pressure overload. Methods and Results Mice established with conditional cardiac-specific P2X4R knockout were subjected to left anterior descending coronary artery ligation–induced postinfarct or transverse aorta constriction–induced pressure overload HF. Knockout cardiac myocytes did not show P2X4R by immunoblotting or by any response to the P2X4R-specific allosteric enhancer ivermectin. Knockout hearts showed normal basal cardiac function but depressed contractile performance in postinfarct and pressure overload models of HF by in vivo echocardiography and ex vivo isolated working heart parameters. P2X4R coimmunoprecipitated and colocalized with nitric oxide synthase 3 (eNOS) in wild-type cardiac myocytes. Mice with cardiac-specific P2X4R overexpression had increased S-nitrosylation, cyclic GMP, NO formation, and were protected from postinfarct and pressure overload HF. Inhibitor of eNOS, L-N5-(1-iminoethyl)ornithine hydrochloride, blocked the salutary effect of cardiac P2X4R overexpression in postinfarct and pressure overload HF as did eNOS knockout. Conclusions This study establishes a new protective role for endogenous cardiac myocyte P2X4R in HF and is the first to demonstrate a physical interaction between the myocyte receptor and eNOS, a mediator of HF protection. PMID:24622244

  14. Uptake and metabolism of the novel peptide angiotensin-(1-12 by neonatal cardiac myocytes.

    Directory of Open Access Journals (Sweden)

    Sarfaraz Ahmad

    Full Text Available BACKGROUND: Angiotensin-(1-12 [Ang-(1-12] functions as an endogenous substrate for the productions of Ang II and Ang-(1-7 by a non-renin dependent mechanism. This study evaluated whether Ang-(1-12 is incorporated by neonatal cardiac myocytes and the enzymatic pathways of ¹²⁵I-Ang-(1-12 metabolism in the cardiac myocyte medium from WKY and SHR rats. METHODOLOGY/PRINCIPAL FINDINGS: The degradation of ¹²⁵I-Ang-(1-12 (1 nmol/L in the cultured medium of these cardiac myocytes was evaluated in the presence and absence of inhibitors for angiotensin converting enzymes 1 and 2, neprilysin and chymase. In both strains uptake of ¹²⁵I-Ang-(1-12 by myocytes occurred in a time-dependent fashion. Uptake of intact Ang-(1-12 was significantly greater in cardiac myocytes of SHR as compared to WKY. In the absence of renin angiotensin system (RAS enzymes inhibitors the hydrolysis of labeled Ang-(1-12 and the subsequent generation of smaller Ang peptides from Ang-(1-12 was significantly greater in SHR compared to WKY controls. ¹²⁵I-Ang-(1-12 degradation into smaller Ang peptides fragments was significantly inhibited (90% in WKY and 71% in SHR in the presence of all RAS enzymes inhibitors. Further analysis of peptide fractions generated through the incubation of Ang-(1-12 in the myocyte medium demonstrated a predominant hydrolytic effect of angiotensin converting enzyme and neprilysin in WKY and an additional role for chymase in SHR. CONCLUSIONS/SIGNIFICANCE: These studies demonstrate that neonatal myocytes sequester angiotensin-(1-12 and revealed the enzymes involved in the conversion of the dodecapeptide substrate to biologically active angiotensin peptides.

  15. Photoelectric recording of mechanical responses of cardiac myocytes.

    Science.gov (United States)

    Meyer, R; Wiemer, J; Dembski, J; Haas, H G

    1987-04-01

    A method to monitor contraction of isolated myocytes by transmicroscopic photometry is illustrated. Two photodiodes are mounted inside an inverse microscope used for visual control of a cell. Illumination of one diode varies in proportion to changes in cell length. The contraction signal is amplified in a comparator circuit. Spatial resolution of the device is in the order of 1 micron which corresponds to about 5% of cell shortening in the fully activated state of contraction. The method was tested on isolated myocytes from guinea-pig ventricle. Optical records of contraction in response to action potentials or during voltage clamp compare well with the contractile behavior of multicellular preparations.

  16. Modulation of excitability, membrane currents and survival of cardiac myocytes by N-acylethanolamines.

    Science.gov (United States)

    Voitychuk, Oleg I; Asmolkova, Valentyna S; Gula, Nadiya M; Sotkis, Ganna V; Galadari, Sehamuddin; Howarth, Frank C; Oz, Murat; Shuba, Yaroslav M

    2012-09-01

    N-acylethanolamines (NAE) are endogenously produced lipids playing important roles in a diverse range of physiological and pathological conditions. In the present study, using whole-cell patch clamp technique, we have for the first time investigated the effects of the most abundantly produced NAEs, N-stearoylethanolamine (SEA) and N-oleoylethanolamine (OEA), on electric excitability and membrane currents in cardiomyocytes isolated from endocardial, epicardial, and atrial regions of neonatal rat heart. SEA and OEA (1-10μM) attenuated electrical activity of the myocytes from all regions of the cardiac muscle by hyperpolarizing resting potential, reducing amplitude, and shortening the duration of the action potential. However, the magnitudes of these effects varied significantly depending on the type of cardiac myocyte (i.e., endocardial, epicardial, atrial) with OEA being generally more potent. OEA and to a lesser extent SEA suppressed in a concentration-dependent manner currents through voltage-gated Na(+) (VGSC) and L-type Ca(2+) (VGCC) channels, but induced variable cardiac myocyte type-dependent effects on background K(+) and Cl(-) conductance. The mechanisms of inhibitory action of OEA on cardiac VGSCs and VGCCs involved influence on channels' activation/inactivation gating and partial blockade of ion permeation. OEA also enhanced the viability of cardiac myocytes by reducing necrosis without a significant effect on apoptosis. We conclude that SEA and OEA attenuate the excitability of cardiac myocytes mainly through inhibition of VGSCs and VGCC-mediated Ca(2+) entry. Since NAEs are known to increase during tissue ischemia and infarction, these effects of NAEs may mediate some of their cardioprotective actions during these pathological conditions.

  17. ROLE OF CALCINEURIN IN ANGIOTENSIN II INDUCED CARDIAC MYOCYTE HYPERTROPHY OF RATS

    Institute of Scientific and Technical Information of China (English)

    符民桂; 张继峰; 许松; 庞永政; 刘乃奎; 唐朝枢

    2001-01-01

    Objective. The present study investigated the role of calcineurin in angiotensin II(AngII) induced cardiac myocyte hypertrophy of rats. Method. The primary cardiac myocytes were cultured under the standard conditions. The calcineurin activity in AngII treated cardiomyocytes was tested by using PNPP;protein synethsis rate was assessed by 3H leucine incorporation; atrial natriuretic factor(ANF) Mrna level was determined by Northern blot analysis. Cell viability was estimated by lactate dehydrogenase(LDH) levels in cultured medium and by dyed cell numbers. Result. After stimulation of 10,100 and 1 000nmol/L of AngII, calcineurin activities in the cardiomyocytes were increased by 13% ,57% (P< 0.05) and 228% (P< 0.01) respectively, compared with control group. Cyclosporin A(CsA), a specific inhibitor of calcineurin, markedly inhibited the calcineurin activity and decreased the 3H leucine incorporation in AngII treated cardiomyocytes in a dose dependent manner. It was also found that CsA slightly reduced the Mrna level of ANF gene in AngII stimulated cardiomyocytes. Conclusion. During AngII induced cardiac myocyte hypertrophy, calcineurin signal pathway is activated, and inhibition of the pathway can attenuate AngII induced cardiac myocyte hypertrophy, which suggests that the calcineurin signal pathway may play an important role in AngII induced myocardial hypertrophy of rats.

  18. An Experimental Model Using Cultured Cardiac Myocytes for a Study of the Generation of Premature Ventricular Contractions Under Ultrasound Exposure

    Science.gov (United States)

    Kudo, Nobuki; Yamamoto, Masaya

    2011-09-01

    It is known that use of a contrast agents in echocardiography increases the probability of generation of premature ventricular contractions (PVCs). As a basic study to elucidate the mechanisms and to reduce adverse effects, the generation of PVCs was investigated using cultured cardiac myocytes instead of the intact heart in vivo. Cardiac myocytes were isolated from neonatal rats and cultured on a cover slip. The myocyte sample was exposed to pulsed ultrasound with microbubbles adjacent to the myocytes, and generation of PVCs was examined with ultrasound exposure at various delay times after onset of myocyte contraction. The experimental results showed that generation of PVCs had a stable threshold delay time and that PVCs were generated only when myocytes were exposed to ultrasound with delay times longer than the threshold. The results indicate that the model used in this study is useful for revealing the mechanisms by which PVCs are induced by ultrasound exposure.

  19. Cardiac Myocyte Diversity and a Fibroblast Network in the Junctional Region of the Zebrafish Heart Revealed by Transmission and Serial Block-Face Scanning Electron Microscopy

    KAUST Repository

    Lafontant, Pascal J.

    2013-08-23

    The zebrafish has emerged as an important model of heart development and regeneration. While the structural characteristics of the developing and adult zebrafish ventricle have been previously studied, little attention has been paid to the nature of the interface between the compact and spongy myocardium. Here we describe how these two distinct layers are structurally and functionally integrated. We demonstrate by transmission electron microscopy that this interface is complex and composed primarily of a junctional region occupied by collagen, as well as a population of fibroblasts that form a highly complex network. We also describe a continuum of uniquely flattened transitional cardiac myocytes that form a circumferential plate upon which the radially-oriented luminal trabeculae are anchored. In addition, we have uncovered within the transitional ring a subpopulation of markedly electron dense cardiac myocytes. At discrete intervals the transitional cardiac myocytes form contact bridges across the junctional space that are stabilized through localized desmosomes and fascia adherentes junctions with adjacent compact cardiac myocytes. Finally using serial block-face scanning electron microscopy, segmentation and volume reconstruction, we confirm the three-dimensional nature of the junctional region as well as the presence of the sheet-like fibroblast network. These ultrastructural studies demonstrate the previously unrecognized complexity with which the compact and spongy layers are structurally integrated, and provide a new basis for understanding development and regeneration in the zebrafish heart. © 2013 Lafontant et al.

  20. Cardiac myocyte diversity and a fibroblast network in the junctional region of the zebrafish heart revealed by transmission and serial block-face scanning electron microscopy.

    Science.gov (United States)

    Lafontant, Pascal J; Behzad, Ali R; Brown, Evelyn; Landry, Paul; Hu, Norman; Burns, Alan R

    2013-01-01

    The zebrafish has emerged as an important model of heart development and regeneration. While the structural characteristics of the developing and adult zebrafish ventricle have been previously studied, little attention has been paid to the nature of the interface between the compact and spongy myocardium. Here we describe how these two distinct layers are structurally and functionally integrated. We demonstrate by transmission electron microscopy that this interface is complex and composed primarily of a junctional region occupied by collagen, as well as a population of fibroblasts that form a highly complex network. We also describe a continuum of uniquely flattened transitional cardiac myocytes that form a circumferential plate upon which the radially-oriented luminal trabeculae are anchored. In addition, we have uncovered within the transitional ring a subpopulation of markedly electron dense cardiac myocytes. At discrete intervals the transitional cardiac myocytes form contact bridges across the junctional space that are stabilized through localized desmosomes and fascia adherentes junctions with adjacent compact cardiac myocytes. Finally using serial block-face scanning electron microscopy, segmentation and volume reconstruction, we confirm the three-dimensional nature of the junctional region as well as the presence of the sheet-like fibroblast network. These ultrastructural studies demonstrate the previously unrecognized complexity with which the compact and spongy layers are structurally integrated, and provide a new basis for understanding development and regeneration in the zebrafish heart.

  1. Cardiac hypertrophy involves both myocyte hypertrophy and hyperplasia in anemic zebrafish.

    Directory of Open Access Journals (Sweden)

    Xiaojing Sun

    Full Text Available BACKGROUND: An adult zebrafish heart possesses a high capacity of regeneration. However, it has been unclear whether and how myocyte hyperplasia contributes to cardiac remodeling in response to biomechanical stress and whether myocyte hypertrophy exists in the zebrafish. To address these questions, we characterized the zebrafish mutant tr265/tr265, whose Band 3 mutation disrupts erythrocyte formation and results in anemia. Although Band 3 does not express and function in the heart, the chronic anemia imposes a sequential biomechanical stress towards the heart. METHODOLOGY/PRINCIPAL FINDINGS: Hearts of the tr265/tr265 Danio rerio mutant become larger than those of the sibling by week 4 post fertilization and gradually exhibit characteristics of human cardiomyopathy, such as muscular disarray, re-activated fetal gene expression, and severe arrhythmia. At the cellular level, we found both increased individual cardiomyocyte size and increased myocyte proliferation can be detected in week 4 to week 12 tr265/tr265 fish. Interestingly, all tr265/tr265 fish that survive after week-12 have many more cardiomyocytes of smaller size than those in the sibling, suggesting that myocyte hyperplasia allows the long-term survival of these fish. We also show the cardiac hypertrophy process can be recapitulated in wild-type fish using the anemia-inducing drug phenylhydrazine (PHZ. CONCLUSIONS/SIGNIFICANCE: The anemia-induced cardiac hypertrophy models reported here are the first adult zebrafish cardiac hypertrophy models characterized. Unlike mammalian models, both cardiomyocyte hypertrophy and hyperplasia contribute to the cardiac remodeling process in these models, thus allowing the effects of cardiomyocyte hyperplasia on cardiac remodeling to be studied. However, since anemia can induce effects on the heart other than biomechanical, non-anemic zebrafish cardiac hypertrophy models shall be generated and characterized.

  2. Transformation of adult rat cardiac myocytes in primary culture.

    Science.gov (United States)

    Banyasz, Tamas; Lozinskiy, Ilya; Payne, Charles E; Edelmann, Stephanie; Norton, Byron; Chen, Biyi; Chen-Izu, Ye; Izu, Leighton T; Balke, C William

    2008-03-01

    We characterized the morphological, electrical and mechanical alterations of cardiomyocytes in long-term cell culture. Morphometric parameters, sarcomere length, T-tubule density, cell capacitance, L-type calcium current (I(Ca,L)), inward rectifier potassium current (I(K1)), cytosolic calcium transients, action potential and contractile parameters of adult rat ventricular myocytes were determined on each day of 5 days in culture. We also analysed the health of the myocytes using an apoptotic/necrotic viability assay. The data show that myocytes undergo profound morphological and functional changes during culture. We observed a progressive reduction in the cell area (from 2502 +/- 70 microm(2) on day 0 to 1432 +/- 50 microm(2) on day 5), T-tubule density, systolic shortening (from 0.11 +/- 0.02 to 0.05 +/- 0.01 microm) and amplitude of calcium transients (from 1.54 +/- 0.19 to 0.67 +/- 0.19) over 5 days of culture. The negative force-frequency relationship, characteristic of rat myocardium, was maintained during the first 2 days but diminished thereafter. Cell capacitance (from 156 +/- 8 to 105 +/- 11 pF) and membrane currents were also reduced (I(Ca,L), from 3.98 +/- 0.39 to 2.12 +/- 0.37 pA pF; and I(K1), from 34.34p +/- 2.31 to 18.00 +/- 5.97 pA pF(-1)). We observed progressive depolarization of the resting membrane potential during culture (from 77.3 +/- 2.5 to 34.2 +/- 5.9 mV) and, consequently, action potential morphology was profoundly altered as well. The results of the viability assays indicate that these alterations could not be attributed to either apoptosis or necrosis but are rather an adaptation to the culture conditions over time.

  3. Predicting changes in cardiac myocyte contractility during early drug discovery with in vitro assays

    Energy Technology Data Exchange (ETDEWEB)

    Morton, M.J., E-mail: michael.morton@astrazeneca.com [Discovery Sciences, AstraZeneca, Macclesfield, Cheshire SK10 4TG (United Kingdom); Armstrong, D.; Abi Gerges, N. [Drug Safety and Metabolism, AstraZeneca, Macclesfield, Cheshire SK10 4TG (United Kingdom); Bridgland-Taylor, M. [Discovery Sciences, AstraZeneca, Macclesfield, Cheshire SK10 4TG (United Kingdom); Pollard, C.E.; Bowes, J.; Valentin, J.-P. [Drug Safety and Metabolism, AstraZeneca, Macclesfield, Cheshire SK10 4TG (United Kingdom)

    2014-09-01

    Cardiovascular-related adverse drug effects are a major concern for the pharmaceutical industry. Activity of an investigational drug at the L-type calcium channel could manifest in a number of ways, including changes in cardiac contractility. The aim of this study was to define which of the two assay technologies – radioligand-binding or automated electrophysiology – was most predictive of contractility effects in an in vitro myocyte contractility assay. The activity of reference and proprietary compounds at the L-type calcium channel was measured by radioligand-binding assays, conventional patch-clamp, automated electrophysiology, and by measurement of contractility in canine isolated cardiac myocytes. Activity in the radioligand-binding assay at the L-type Ca channel phenylalkylamine binding site was most predictive of an inotropic effect in the canine cardiac myocyte assay. The sensitivity was 73%, specificity 83% and predictivity 78%. The radioligand-binding assay may be run at a single test concentration and potency estimated. The least predictive assay was automated electrophysiology which showed a significant bias when compared with other assay formats. Given the importance of the L-type calcium channel, not just in cardiac function, but also in other organ systems, a screening strategy emerges whereby single concentration ligand-binding can be performed early in the discovery process with sufficient predictivity, throughput and turnaround time to influence chemical design and address a significant safety-related liability, at relatively low cost. - Highlights: • The L-type calcium channel is a significant safety liability during drug discovery. • Radioligand-binding to the L-type calcium channel can be measured in vitro. • The assay can be run at a single test concentration as part of a screening cascade. • This measurement is highly predictive of changes in cardiac myocyte contractility.

  4. The Electrophysiological Effects of Qiliqiangxin on Cardiac Ventricular Myocytes of Rats

    Directory of Open Access Journals (Sweden)

    Yidong Wei

    2013-01-01

    Full Text Available Qiliqiangxin, a Chinese herb, represents the affection in Ca channel function of cardiac myocytes. It is unknown whether Qiliqiangxin has an effect on Na current and K current because the pharmacological actions of this herb’s compound are very complex. We investigated the rational usage of Qiliqiangxin on cardiac ventricular myocytes of rats. Ventricular myocytes were exposed acutely to 1, 10, and 50 mg/L Qiliqiangxin, and whole cell patch-clamp technique was used to study the acute effects of Qiliqiangxin on Sodium current (INa, outward currents delayed rectifier outward K+ current (IK, slowly activating delayed rectifier outward K+ current (IKs, transient outward K+ current (Ito, and inward rectifier K+ current (IK1. Qiliqiangxin can decrease INa by 28.53%±5.98%, and its IC50 was 9.2 mg/L. 10 and 50 mg/L Qiliqiangxin decreased by 37.2%±6.4% and 55.9%±5.5% summit current density of Ito. 10 and 50 mg/L Qiliqiangxin decreased IKs by 15.51%±4.03% and 21.6%±5.6%. Qiliqiangxin represented a multifaceted pharmacological profile. The effects of Qiliqiangxin on Na and K currents of ventricular myocytes were more profitable in antiarrhythmic therapy in the clinic. We concluded that the relative efficacy of Qiliqiangxin was another choice for the existing antiarrhythmic therapy.

  5. Optimisation of a Generic Ionic Model of Cardiac Myocyte Electrical Activity

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    Tianruo Guo

    2013-01-01

    Full Text Available A generic cardiomyocyte ionic model, whose complexity lies between a simple phenomenological formulation and a biophysically detailed ionic membrane current description, is presented. The model provides a user-defined number of ionic currents, employing two-gate Hodgkin-Huxley type kinetics. Its generic nature allows accurate reconstruction of action potential waveforms recorded experimentally from a range of cardiac myocytes. Using a multiobjective optimisation approach, the generic ionic model was optimised to accurately reproduce multiple action potential waveforms recorded from central and peripheral sinoatrial nodes and right atrial and left atrial myocytes from rabbit cardiac tissue preparations, under different electrical stimulus protocols and pharmacological conditions. When fitted simultaneously to multiple datasets, the time course of several physiologically realistic ionic currents could be reconstructed. Model behaviours tend to be well identified when extra experimental information is incorporated into the optimisation.

  6. Modeling calcium wave based on anomalous subdiffusion of calcium sparks in cardiac myocytes.

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    Xi Chen

    Full Text Available Ca(2+ sparks and Ca(2+ waves play important roles in calcium release and calcium propagation during the excitation-contraction (EC coupling process in cardiac myocytes. Although the classical Fick's law is widely used to model Ca(2+ sparks and Ca(2+ waves in cardiac myocytes, it fails to reasonably explain the full-width at half maximum(FWHM paradox. However, the anomalous subdiffusion model successfully reproduces Ca(2+ sparks of experimental results. In this paper, in the light of anomalous subdiffusion of Ca(2+ sparks, we develop a mathematical model of calcium wave in cardiac myocytes by using stochastic Ca(2+ release of Ca(2+ release units (CRUs. Our model successfully reproduces calcium waves with physiological parameters. The results reveal how Ca(2+ concentration waves propagate from an initial firing of one CRU at a corner or in the middle of considered region, answer how large in magnitude of an anomalous Ca(2+ spark can induce a Ca(2+ wave. With physiological Ca(2+ currents (2pA through CRUs, it is shown that an initial firing of four adjacent CRUs can form a Ca(2+ wave. Furthermore, the phenomenon of calcium waves collision is also investigated.

  7. FINITE ELEMENT ANALYSIS OF CARDIAC MYOCYTE DEBONDING AND REORIENTATION DURING CYCLIC SUBSTRATE STRETCH EXPERIMENTS

    Institute of Scientific and Technical Information of China (English)

    Tao Tang; Jun Qiu; Meng Zhang; Zhuo Zhuang

    2009-01-01

    The substrate stretch experiment, which is carried out on several kinds of adherent cells, is usually used to catch the physiological variation and morphological response to cyclic substrate deformation. In this paper, stretch loading was exerted on cardiac myocytes cultured on silica substrates using a custom-made substrate stretch device. The effect of stretch on the alignment orientation of cardiac myocytes was studied through morphocytological statistics. Under cyclic stretch stimulus, the long axes of cardiac myocytes oriented perpendicularly to the stretch direction for continuous stretch acting. However, the mechanism underlying these behaviors is not well understood from such in vitro tests. Finite element (FE) model was developed in the analysis to investigate these behaviors. Xu-Needleman formulation was used to define the interaction behavior for contact surfaces between cell and substrate. The role of cell viscoelasticity nature is studied in adherent cell debonding with the substrate and aligning perpendicular to the stretch direction during long time cyclic stretch stimulation. There were four different strain magnitudes considered in the simulation to find out the cell debonding affected by the cyclic strains. The potential role of cyclic strain frequency in regulating cell debonding and alignment was also studied using FE analysis.

  8. Stability of beating frequency in cardiac myocytes by their community effect measured by agarose microchamber chip

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    Yasuda Kenji

    2005-05-01

    Full Text Available Abstract To understand the contribution of community effect on the stability of beating frequency in cardiac myocyte cell groups, the stepwise network formation of cells as the reconstructive approach using the on-chip agarose microchamber cell microcultivation system with photo-thermal etching method was applied. In the system, the shapes of agarose microstructures were changed step by step with photo-thermal etching of agarose-layer of the chip using a 1064-nm infrared focused laser beam to increase the interaction of cardiac myocyte cells during cultivation. First, individual rat cardiac myocyte in each microstructure were cultivated under isolated condition, and then connected them one by one through newly-created microchannels by photo-thermal etching to compare the contribution of community size for the magnitude of beating stability of the cell groups. Though the isolated individual cells have 50% fluctuation of beating frequency, their stability increased as the number of connected cells increased. And finally when the number reached to eight cells, they stabilized around the 10% fluctuation, which was the same magnitude of the tissue model cultivated on the dish. The result indicates the importance of the community size of cells to stabilize their performance for making cell-network model for using cells for monitoring their functions like the tissue model.

  9. PARM-1 is an endoplasmic reticulum molecule involved in endoplasmic reticulum stress-induced apoptosis in rat cardiac myocytes.

    Directory of Open Access Journals (Sweden)

    Koji Isodono

    Full Text Available To identify novel transmembrane and secretory molecules expressed in cardiac myocytes, signal sequence trap screening was performed in rat neonatal cardiac myocytes. One of the molecules identified was a transmembrane protein, prostatic androgen repressed message-1 (PARM-1. While PARM-1 has been identified as a gene induced in prostate in response to castration, its function is largely unknown. Our expression analysis revealed that PARM-1 was specifically expressed in hearts and skeletal muscles, and in the heart, cardiac myocytes, but not non-myocytes expressed PARM-1. Immunofluorescent staining showed that PARM-1 was predominantly localized in endoplasmic reticulum (ER. In Dahl salt-sensitive rats, high-salt diet resulted in hypertension, cardiac hypertrophy and subsequent heart failure, and significantly stimulated PARM-1 expression in the hearts, with a concomitant increase in ER stress markers such as GRP78 and CHOP. In cultured cardiac myocytes, PARM-1 expression was stimulated by proinflammatory cytokines, but not by hypertrophic stimuli. A marked increase in PARM-1 expression was observed in response to ER stress inducers such as thapsigargin and tunicamycin, which also induced apoptotic cell death. Silencing PARM-1 expression by siRNAs enhanced apoptotic response in cardiac myocytes to ER stresses. PARM-1 silencing also repressed expression of PERK and ATF6, and augmented expression of CHOP without affecting IRE-1 expression and JNK and Caspase-12 activation. Thus, PARM-1 expression is induced by ER stress, which plays a protective role in cardiac myocytes through regulating PERK, ATF6 and CHOP expression. These results suggested that PARM-1 is a novel ER transmembrane molecule involved in cardiac remodeling in hypertensive heart disease.

  10. Cardiac fibroblasts are predisposed to convert into myocyte phenotype: Specific effect of transforming growth factor. beta

    Energy Technology Data Exchange (ETDEWEB)

    Eghbali, M.; Tomek, R.; Woods, C.; Bhambi, B. (Univ. of Chicago, IL (United States))

    1991-02-01

    Cardiac fibroblasts are mainly responsible for the synthesis of major extracellular matrix proteins in the heart, including fibrillar collagen types I and III and fibronectin. In this report we show that these cells, when stimulated by transforming growth factor {beta}{sub 1} (TGF-{beta}{sub 1}), acquire certain myocyte-specific properties. Cultured cardiac fibroblasts from adult rabbit heart were treated with TGF-{beta}{sub 1}, (10-15 ng/ml) for different periods of time. Northern hybridization analysis of total RNA showed that cells treated with TGF-{beta}{sub 1} became stained with a monoclonal antibody to muscle-specific actin. After treatment of quiescent cells with TGF-{beta}{sub 1}, cell proliferation (as measured by ({sup 3}H)thymidine incorporation) was moderately increased. Cultured cardiac fibroblasts at the subconfluent stage, when exposed to TGF-{beta}{sub 1} in the presence of 10% fetal bovine serum, gave rise to a second generation of slowly growing cells that expressed muscle-specific actin filaments. The findings demonstrate that cardiac fibroblasts can be made to differentiate into cells that display many characteristics of cardiac myocytes. TGF-{beta}{sub 1} seems to be a specific inducer of such conversion.

  11. Calcium Imaging in Pluripotent Stem Cell-Derived Cardiac Myocytes.

    Science.gov (United States)

    Walter, Anna; Šarić, Tomo; Hescheler, Jürgen; Papadopoulos, Symeon

    2016-01-01

    The possibility to generate cardiomyocytes (CMs) from disease-specific induced pluripotent stem cells (iPSCs) is a powerful tool for the investigation of various cardiac diseases in vitro. The pathological course of various cardiac conditions, causatively heterogeneous, often converges into disturbed cellular Ca(2+) cycling. The gigantic Ca(2+) channel of the intracellular Ca(2+) store of CMs, the ryanodine receptor type 2 (RyR2), controls Ca(2+) release and therefore plays a crucial role in Ca(2+) cycling of CMs. In the present protocol we describe ways to measure and analyze global as well as local cellular Ca(2+) release events in CMs derived from a patient carrying a CPVT-causing RyR2 mutation.

  12. Bnip3 Binds and Activates p300: Possible Role in Cardiac Transcription and Myocyte Morphology.

    Directory of Open Access Journals (Sweden)

    John W Thompson

    Full Text Available Bnip3 is a hypoxia-regulated member of the Bcl-2 family of proteins that is implicated in apoptosis, programmed necrosis, autophagy and mitophagy. Mitochondria are thought to be the primary targets of Bnip3 although its activities may extend to the ER, cytoplasm, and nucleus. Bnip3 is induced in the heart by ischemia and pressure-overload, and may contribute to cardiomyopathy and heart failure. Only mitochondrial-dependent programmed death actions have been described for Bnip3 in the heart. Here we describe a novel activity of Bnip3 in cultured cardiac myocytes and transgenic mice overexpressing Bnip3 in the heart (Bnip3-TG. In cultured myocytes Bnip3 bound and activated the acetyltransferase p300, increased acetylation of histones and the transcription factor GATA4, and conferred p300 and GATA4-sensitive cellular morphological changes. In intact Bnip3-TG hearts Bnip3 also bound p300 and GATA4 and conferred enhanced GATA4 acetylation. Bnip3-TG mice underwent age-dependent ventricular dilation and heart failure that was partially prevented by p300 inhibition with curcumin. The results suggest that Bnip3 regulates cardiac gene expression and perhaps myocyte morphology by activating nuclear p300 acetyltransferase activity and hyperacetylating histones and p300-selective transcription factors.

  13. Cell-specific promoter in adenovirus vector for transgenic expression of SERCA1 ATPase in cardiac myocytes.

    Science.gov (United States)

    Inesi, G; Lewis, D; Sumbilla, C; Nandi, A; Strock, C; Huff, K W; Rogers, T B; Johns, D C; Kessler, P D; Ordahl, C P

    1998-03-01

    Adenovirus-mediated transfer of cDNA encoding the chicken skeletal muscle sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA1) yielded selective expression in cultured chick embryo cardiac myocytes under control of a segment (-268 base pair) of the cell-specific cardiac troponin T (cTnT) promoter or nonselective expression in myocytes and fibroblasts under control of a constitutive viral [cytomegalovirus (CMV)] promoter. Under optimal conditions nearly all cardiac myocytes in culture were shown to express transgenic SERCA1 ATPase. Expression was targeted to intracellular membranes and was recovered in subcellular fractions with a pattern identical to that of the endogenous SERCA2a ATPase. Relative to control myocytes, transgenic SERCA1 expression increased up to four times the rates of ATP-dependent (and thapsigargin-sensitive) Ca2+ transport activity of cell homogenates. Although the CMV promoter was more active than the cTnT promoter, an upper limit for transgenic expression of functional enzyme was reached under control of either promoter by adjustment of the adenovirus plaque-forming unit titer of infection media. Cytosolic Ca2+ concentration transients and tension development of whole myocytes were also influenced to a similar limit by transgenic expression of SERCA1 under control of either promoter. Our experiments demonstrate that a cell-specific protein promoter in recombinant adenovirus vectors yields highly efficient and selective transgene expression of a membrane-bound and functional enzyme in cardiac myocytes.

  14. Acquisition of a Quantitative, Stoichiometrically Conserved Ratiometric Marker of Maturation Status in Stem Cell-Derived Cardiac Myocytes

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    Fikru B. Bedada

    2014-10-01

    Full Text Available There is no consensus in the stem cell field as to what constitutes the mature cardiac myocyte. Thus, helping formalize a molecular signature for cardiac myocyte maturation would advance the field. In the mammalian heart, inactivation of the “fetal” TNNI gene, TNNI1 (ssTnI, together in temporal concert with its stoichiometric replacement by the adult TNNI gene product, TNNI3 (cTnI, represents a quantifiable ratiometric maturation signature. We examined the TNNI isoform transition in human induced pluripotent stem cell (iPSC cardiac myocytes (hiPSC-CMs and found the fetal TNNI signature, even during long-term culture. Rodent stem cell-derived and primary myocytes, however, transitioned to the adult TnI profile. Acute genetic engineering of hiPSC-CMs enabled a rapid conversion toward the mature TnI profile. While there is no single marker to denote the mature cardiac myocyte, we propose that tracking the cTnI:ssTnI protein isoform ratio provides a valuable maturation signature to quantify myocyte maturation status across laboratories.

  15. Effects of simulated microgravity on nitric oxide level in cardiac myocytes and its mechanism

    Institute of Scientific and Technical Information of China (English)

    熊江辉; 李莹辉; 聂捷琳

    2003-01-01

    The depression of cardiac contractility induced by space microgravity is an important issue of aerospace medicine research, while its precise mechanism is still unknown. In the present study, we explored effects of simulated microgravity on nitric oxide (NO) level, inducible nitric oxide synthase (iNOS) expression and related regulative mechanism using electron spin resonance (ESR) spectroscopy, immunocytochemistry and in situ hybridization. We found a remarkable increase of NO level and up-regulation of iNOS and iNOS mRNA expression in rat cardiac myocytes under simulated microgravity. Staurosporine (a nonselective protein kinase inhibitor), calphostin C (a selective protein kinase C inhibitor), partially inhibited the effect of simulated microgravity. Thus regulative effect of simulated microgravity on iNOS expression is mediated at least partially via activation of protein kinase C. These results indicate that NO system in cardiac myocytes is sensitive to simulated microgravity and may play an important role in the depression of cardiac contractility induced by simulated microgravity.

  16. Insulin improves cardiac myocytes contractile function recovery in simulated ischemia-reperfusion: Key role of Akt

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bo; ZHANG Haifeng; FAN Qian; MA Xinliang; GAO Feng

    2003-01-01

    The present study examined cardiac myocyte contractile and Ca2+ transient responses to insulin during simulated ischemia/reperfusion (I/R) and furtherinvestigated the role of protein kinase B (Akt) in the insulin- induced inotropic effect. Ventricular myocytes were enzymatically isolated from adult Sprague-Dawley rats and perfused with Tyrode solution while electrically field-stimulated. Simulated I/R was induced by perfusing the cells with chemical anoxic solution including sodium cyanide-sodium lactate for 15 min followed by reperfusion with normal oxygenated Tyrode solution with or without insulin. It is found that insulin only at concentration as high as 10 IU/L could increase cell shortening (16±5%, P < 0.05) in normal myocytes, whereas it concentration-dependently (0.01-10 IU/L) increased the contraction,the velocity of shortening/releng- theningand Ca2+ transient in I/R myocytes. In addition, insulin treatment (1 IU/L) increased Akt phosphorylation of I/R cardiomyocytes by 2.4-fold compared with that of the control (P < 0.01). Most importantly, pretreatment with LY 294002, a specific inhibitor of phosphatidylinositol 3′-kinase (PI3-kinase), significantly inhibited both Akt phosphorylation and the positive inotropic response to insulin in the I/R cardiomyocytes. These results suggest that insulin exerts direct positive inotropic effect by increasing Ca2+ transient of cardiomyocytes, which is enhanced in the pathological condition of I/R. Akt activation plays an important role in the insulin-induced improvement of myocyte contractile function following I/R.

  17. Speckle based configuration for simultaneous in vitro inspection of mechanical contractions of cardiac myocyte cells

    Science.gov (United States)

    Golberg, Mark; Fixler, Dror; Shainberg, Asher; Zlochiver, Sharon; Micó, Vicente; Garcia, Javier; Beiderman, Yevgeny; Zalevsky, Zeev

    2013-04-01

    In this manuscript we propose optical lensless configuration for a remote non-contact measuring of mechanical contractions of vast number of cardiac myocytes. All the myocytes were taken from rats, and the measurements were done in an in vitro mode. The optical method is based on temporal analysis of secondary reflected speckle patterns generated in lensless microscope configuration. The processing involves analyzing the movement and the change in the statistics of the generated secondary speckle patterns that are created on top of the cell culture when it is illuminated by a spot of laser beam. The main advantage of the proposed system is the ability to measure many cells simultaneously (approximately one thousand cells) and to extract the statistical data of their movement at once. The presented experimental results also include investigation the effect of isoproteranol on cells contraction process.

  18. Genetically engineered cardiac pacemaker: Stem cells transfected with HCN2 gene and myocytes-A model

    Energy Technology Data Exchange (ETDEWEB)

    Kanani, S. [Institut Genomique Fonctionelle, 141 Rue de la Cardonille, 34396 Montpellier (France); Institut Non Lineaire de Nice, CNRS and Universite de Nice, 1361 route des Lucioles, 06560 Valbonne (France); Pumir, A. [Institut Non Lineaire de Nice, CNRS and Universite de Nice, 1361 route des Lucioles, 06560 Valbonne (France); Laboratoire J.A. Dieudonne, CNRS and Universite de Nice, Parc Valrose, 06108 Nice (France)], E-mail: alain.pumir@unice.fr; Krinsky, V. [Institut Non Lineaire de Nice, CNRS and Universite de Nice, 1361 route des Lucioles, 06560 Valbonne (France)

    2008-01-07

    One of the successfully tested methods to design genetically engineered cardiac pacemaker cells consists in transfecting a human mesenchymal stem cell (hMSC) with a HCN2 gene and connecting it to a myocyte. We develop and study a mathematical model, describing a myocyte connected to a hMSC transfected with a HCN2 gene. The cardiac action potential is described both with the simple Beeler-Reuter model, as well as with the elaborate dynamic Luo-Rudy model. The HCN2 channel is described by fitting electrophysiological records, in the spirit of Hodgkin-Huxley. The model shows that oscillations can occur in a pair myocyte-stem cell, that was not observed in the experiments yet. The model predicted that: (1) HCN pacemaker channels can induce oscillations only if the number of expressed I{sub K1} channels is low enough. At too high an expression level of I{sub K1} channels, oscillations cannot be induced, no matter how many pacemaker channels are expressed. (2) At low expression levels of I{sub K1} channels, a large domain of values in the parameter space (n, N) exists, where oscillations should be observed. We denote N the number of expressed pacemaker channels in the stem cell, and n the number of gap junction channels coupling the stem cell and the myocyte. (3) The expression levels of I{sub K1} channels observed in ventricular myocytes, both in the Beeler-Reuter and in the dynamic Luo-Rudy models are too high to allow to observe oscillations. With expression levels below {approx}1/4 of the original value, oscillations can be observed. The main consequence of this work is that in order to obtain oscillations in an experiment with a myocyte-stem cell pair, increasing the values of n, N is unlikely to be helpful, unless the expression level of I{sub K1} has been reduced enough. The model also allows us to explore levels of gene expression not yet achieved in experiments, and could be useful to plan new experiments, aimed at improving the robustness of the oscillations.

  19. RyR2 modulates a Ca2+-activated K+ current in mouse cardiac myocytes.

    Directory of Open Access Journals (Sweden)

    Yong-Hui Mu

    Full Text Available In cardiomyocytes, Ca2+ entry through voltage-dependent Ca2+ channels (VDCCs binds to and activates RyR2 channels, resulting in subsequent Ca2+ release from the sarcoplasmic reticulum (SR and cardiac contraction. Previous research has documented the molecular coupling of small-conductance Ca2+-activated K+ channels (SK channels to VDCCs in mouse cardiac muscle. Little is known regarding the role of RyRs-sensitive Ca2+ release in the SK channels in cardiac muscle. In this study, using whole-cell patch clamp techniques, we observed that a Ca2+-activated K+ current (IK,Ca recorded from isolated adult C57B/L mouse atrial myocytes was significantly decreased by ryanodine, an inhibitor of ryanodine receptor type 2 (RyR2, or by the co-application of ryanodine and thapsigargin, an inhibitor of the sarcoplasmic reticulum calcium ATPase (SERCA (p<0.05, p<0.01, respectively. The activation of RyR2 by caffeine increased the IK,Ca in the cardiac cells (p<0.05, p<0.01, respectively. We further analyzed the effect of RyR2 knockdown on IK,Ca and Ca2+ in isolated adult mouse cardiomyocytes using a whole-cell patch clamp technique and confocal imaging. RyR2 knockdown in mouse atrial cells transduced with lentivirus-mediated small hairpin interference RNA (shRNA exhibited a significant decrease in IK,Ca (p<0.05 and [Ca2+]i fluorescence intensity (p<0.01. An immunoprecipitated complex of SK2 and RyR2 was identified in native cardiac tissue by co-immunoprecipitation assays. Our findings indicate that RyR2-mediated Ca2+ release is responsible for the activation and modulation of SK channels in cardiac myocytes.

  20. Microfluidic systems to examine intercellular coupling of pairs of cardiac myocytes.

    Science.gov (United States)

    Klauke, Norbert; Smith, Godfrey; Cooper, Jonathan M

    2007-06-01

    In this paper we describe a microfluidic environment that enables us to explore cell-to-cell signalling between longitudinally linked primary heart cells. We have chosen to use pairs (or doublets) of cardiac myocyte as a model system, not only because of the importance of cell-cell signalling in the study of heart disease but also because the single cardiomyocytes are both mechanically and electrically active and their synchronous activation due to the intercellular coupling within the doublet can be readily monitored on optical and electrical recordings. Such doublets have specialised intercellular contact structures in the form of the intercalated discs, comprising the adhesive junction (fascia adherens and macula adherens or desmosome) and the connecting junction (known as gap junction). The latter structure enables adjacent heart cells to share ions, second messengers and small metabolites (<1 kDa) between them and thus provides the structural basis for the synchronous (syncytical) behaviour of connected cardiomyocytes. Using the unique environment provided by the microfluidic system, described in this paper, we explore the local ionic conditions that enable the propagation of Ca(2+) waves between two heart cells. We observe that the ability of intracellular Ca(2+) waves to traverse the intercalated discs is dependent on the relative concentrations of diastolic Ca(2+) in the two adjacent cells. These experiments rely upon our ability to independently control both the electrical stimulation of each of the cells (using integrated microelectrodes) and to rapidly change (or switch) the local concentrations of ions and drugs in the extracellular buffer within the microfluidic channel (using a nanopipetting system). Using this platform, it is also possible to make simultaneous optical recordings (including fluorescence and cell contraction) to explore the effect of drugs on one or both cells, within the doublet.

  1. Developmental remodeling and shortening of the cardiac outflow tract involves myocyte programmed cell death.

    Science.gov (United States)

    Watanabe, M; Choudhry, A; Berlan, M; Singal, A; Siwik, E; Mohr, S; Fisher, S A

    1998-10-01

    The embryonic outflow tract is a simple tubular structure that connects the single primitive ventricle with the aortic sac and aortic arch arteries. This structure undergoes a complex sequence of morphogenetic processes to become the portion of the heart that aligns the right and left ventricles with the pulmonary artery and aorta. Abnormalities of the outflow tract are involved in many clinically significant congenital cardiac defects; however, the cellular and molecular processes governing the development of this important structure are incompletely understood. Histologic and tissue-tagging studies indicate that the outflow tract tissues compact and are incorporated predominantly into a region of the right ventricle. The hypothesis tested in the current study was that cell death or apoptosis in the muscular portion of the outflow tract is an important cellular mechanism for outflow tract shortening. The tubular outflow tract myocardium was specifically marked by infecting myocytes of the chicken embryo heart with a recombinant replication-defective adenovirus expressing beta-galactosidase (beta-gal) under the control of the cytomegalovirus promoter. Histochemical detection of the beta -gal-labeled outflow tract myocytes revealed that the tubular structure shortened to become a compact ring at the level of the pulmonic infundibulum over several days of development (stages 25-32, embryonic days 4-8). The appearance of apoptotic cardiomyocytes was correlated with OFT shortening by two histologic assays, TUNEL labeling of DNA fragments and AnnexinV binding. The rise and fall in the number of apoptotic myocytes detected by histologic analyses paralleled the change in activity levels of Caspase-3, a protease in the apoptotic cascade, measured in outflow tract homogenates. These results suggest that the elimination of myocytes by programmed cell death is one mechanism by which the outflow tract myocardium remodels to form the proper connection between the ventricular

  2. Myosin light chain 2-based selection of human iPSC-derived early ventricular cardiac myocytes

    Science.gov (United States)

    Bizy, Alexandra; Guerrero-Serna, Guadalupe; Hu, Bin; Ponce-Balbuena, Daniela; Willis, B. Cicero; Zarzoso, Manuel; Ramirez, Rafael J.; Sener, Michelle F.; Mundada, Lakshmi V.; Klos, Matthew; Devaney, Eric J.; Vikstrom, Karen L.; Herron, Todd J.; Jalife, José

    2014-01-01

    Applications of human induced pluripotent stemcell derived-cardiac myocytes (hiPSC-CMs) would be strengthened by the ability to generate specific cardiac myocyte (CM) lineages. However, purification of lineage-specific hiPSC-CMs is limited by the lack of cell marking techniques. Here, we have developed an iPSC-CM marking system using recombinant adenoviral reporter constructs with atrial- or ventricular-specific myosin light chain-2 (MLC-2) promoters. MLC-2a and MLC-2v selected hiPSC-CMs were purified by fluorescence-activated cell sorting and their biochemical and electrophysiological phenotypes analyzed. We demonstrate that the phenotype of both populations remained stable in culture and they expressed the expected sarcomeric proteins, gap junction proteins and chamber-specific transcription factors. Compared to MLC-2a cells, MLC-2v selected CMs had larger action potential amplitudes and durations. In addition, by immunofluorescence, we showed that MLC-2 isoform expression can be used to enrich hiPSC-CM consistent with early atrial and ventricularmyocyte lineages. However, only the ventricular myosin light chain-2 promoter was able to purify a highly homogeneous population of iPSC-CMs. Using this approach, it is now possible to develop ventricular-specific disease models using iPSC-CMs while atrial-specific iPSC-CM cultures may require additional chamber-specific markers. PMID:24095945

  3. Effect of Sodium Tanshinone Ⅱ A Sulfonate on Cardiac Myocyte Hypertrophy and Its Underlying Mechanism

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Objective:To investigate the effects of sodium tanshinone Ⅱ A sulfonate (STS) on the hypertrophy induced by angiotensin Ⅱ (Ang Ⅱ) in primary cultured neonatal rat cardiac myocytes.Methods:The effect of STS on cytotoxicity was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-3,5-phenytetrazoliumromide (MTT) assay.As indexes for cardiocyte hypertrophy,cell size was determined by phase contrast microscopy and protein synthesis rate was measured by 3H-leucine incorporation.The proto-oncogene c-fos mRNA expression of cardiocytes was assessed using reverse transcription polymerase chain reaction (RT-PCR).Results:STS could inhibit cardiocyte hypertrophy,increase the protein synthesis rate and enhance proto-oncogene c-los mRNA expression in cardiocytes induced by Ang Ⅱ (P<0.01),with an effect similar to that of Valsartan,the Ang Ⅱ receptor antagonist.Conclusion:STS can prevent the hypertrophy of cardiac myocytes induced by Ang Ⅱ,which may be related to its inhibition of the expression of proto-oncogene c-fos mRNA.

  4. C-reactive protein inhibits survivin expression via Akt/mTOR pathway downregulation by PTEN expression in cardiac myocytes.

    Directory of Open Access Journals (Sweden)

    Beom Seob Lee

    Full Text Available C-reactive protein (CRP is one of the most important biomarkers for arteriosclerosis and cardiovascular disease. Recent studies have shown that CRP affects cell cycle and inflammatory process in cardiac myocytes. Survivin is also involved in cardiac myocytes replication and apoptosis. Reduction of survivin expression is associated with less favorable cardiac remodeling in animal models. However, the effect of CRP on survivin expression and its cellular mechanism has not yet been studied. We demonstrated that treatment of CRP resulted in a significant decrease of survivin protein expression in a concentration-dependent manner in cardiac myocytes. The upstream signaling proteins of survivin, such as Akt, mTOR and p70S6K, were also downregulated by CRP treatment. In addition, CRP increased the protein and mRNA levels of PTEN. The siRNA transfection or specific inhibitor treatment for PTEN restored the CRP-induced downregulation of Akt/mTOR/p70S6K pathway and survivin protein expression. Moreover, pretreatment with a specific p53 inhibitor decreased the CRP-induced PTEN expression. ERK-specific inhibitor also blocked the p53 phosphorylation and PTEN expression induced by CRP. Our study provides a novel insight into CRP-induced downregulation of survivin protein expression in cardiac myocytes through mechanisms that involved in downregulation of Akt/mTOR/p70S6K pathway by expression of PTEN.

  5. Expression of androgen-binding protein (ABP) in human cardiac myocytes.

    Science.gov (United States)

    Schock, H W; Herbert, Z; Sigusch, H; Figulla, H R; Jirikowski, G F; Lotze, U

    2006-04-01

    Cardiomyocytes are known to be androgen targets. Changing systemic steroid levels are thought to be linked to various cardiac ailments, including dilated cardiomyopathy (DCM). The mode of action of gonadal steroid hormones on the human heart is unknown to date. In the present study, we used high-resolution immunocytochemistry on semithin sections (1 microm thick), IN SITU hybridization, and mass spectrometry to investigate the expression of androgen-binding protein (ABP) in human myocardial biopsies taken from male patients with DCM. We observed distinct cytoplasmic ABP immunoreactivity in a fraction of the myocytes. IN SITU hybridization with synthetic oligonucleotide probes revealed specific hybridization signals in these cells. A portion of the ABP-positive cells contained immunostaining for androgen receptor. With SELDI TOF mass spectrometry of affinity purified tissue extracts of human myocardium, we confirmed the presence of a 50 kDa protein similar to ABP. Our observations provide evidence of an intrinsic expression of ABP in human heart. ABP may be secreted from myocytes in a paracrine manner perhaps to influence the bioavailabity of gonadal steroids in myocardium.

  6. Carbon nanotubes enhance intercalated disc assembly in cardiac myocytes via the β1-integrin-mediated signaling pathway.

    Science.gov (United States)

    Sun, Hongyu; Lü, Shuanghong; Jiang, Xiao-Xia; Li, Xia; Li, Hong; Lin, Qiuxia; Mou, Yongchao; Zhao, Yuwei; Han, Yao; Zhou, Jin; Wang, Changyong

    2015-07-01

    Carbon nanotubes (CNTs) offer a new paradigm for constructing functional cardiac patches and repairing myocardial infarction (MI). However, little is known about how CNTs enhance the mechanical integrity and electrophysiological function of cardiac myocytes. To address this issue, we investigated the regularity and precise mechanism of the influence of CNTs on the assembly of intercalated disc (IDs). Here, single walled CNTs incorporated into collagen substrates were utilized as growth supports for neonatal cardiomyocytes, which enhanced cardiomyocyte adhesion and maturation. Furthermore, through the use of immunohistochemical staining, western blotting, transmission electron microscopy, and intracellular calcium transient measurement, we discovered that the addition of CNTs remarkably increased ID-related protein expression and enhanced ID assembly and functionality. On that basis, we further explored the underlying mechanism for how CNTs enhanced ID assembly through the use of immunohistochemical staining and western blotting. We found that the β1-integrin-mediated signaling pathway mediated CNT-induced upregulation of electrical and mechanical junction proteins. Notably, CNTs remarkably accelerated gap junction formation via activation of the β1-integrin-mediated FAK/ERK/GATA4 pathway. These findings provide valuable insight into the mechanistic effects that CNTs have on neonatal cardiomyocyte performance and will have a significant impact on the future of nanomedical research.

  7. PGC-1{alpha} accelerates cytosolic Ca{sup 2+} clearance without disturbing Ca{sup 2+} homeostasis in cardiac myocytes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Min, E-mail: chenminyx@gmail.com [Institute of Molecular Medicine, State Key Laboratory of Biomembrane and Membrane Biotechnology, Peking University, Beijing 100871 (China); Yunnan Centers for Diseases Prevention and Control, Kunming 650022 (China); Wang, Yanru [Institute of Molecular Medicine, State Key Laboratory of Biomembrane and Membrane Biotechnology, Peking University, Beijing 100871 (China); Qu, Aijuan [Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 (United States)

    2010-06-11

    Energy metabolism and Ca{sup 2+} handling serve critical roles in cardiac physiology and pathophysiology. Peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1{alpha}) is a multi-functional coactivator that is involved in the regulation of cardiac mitochondrial functional capacity and cellular energy metabolism. However, the regulation of PGC-1{alpha} in cardiac Ca{sup 2+} signaling has not been fully elucidated. To address this issue, we combined confocal line-scan imaging with off-line imaging processing to characterize calcium signaling in cultured adult rat ventricular myocytes expressing PGC-1{alpha} via adenoviral transduction. Our data shows that overexpressing PGC-1{alpha} improved myocyte contractility without increasing the amplitude of Ca{sup 2+} transients, suggesting that myofilament sensitivity to Ca{sup 2+} increased. Interestingly, the decay kinetics of global Ca{sup 2+} transients and Ca{sup 2+} waves accelerated in PGC-1{alpha}-expressing cells, but the decay rate of caffeine-elicited Ca{sup 2+} transients showed no significant change. This suggests that sarcoplasmic reticulum (SR) Ca{sup 2+}-ATPase (SERCA2a), but not Na{sup +}/Ca{sup 2+} exchange (NCX) contribute to PGC-1{alpha}-induced cytosolic Ca{sup 2+} clearance. Furthermore, PGC-1{alpha} induced the expression of SERCA2a in cultured cardiac myocytes. Importantly, overexpressing PGC-1{alpha} did not disturb cardiac Ca{sup 2+} homeostasis, because SR Ca{sup 2+} load and the propensity for Ca{sup 2+} waves remained unchanged. These data suggest that PGC-1{alpha} can ameliorate cardiac Ca{sup 2+} cycling and improve cardiac work output in response to physiological stress. Unraveling the PGC-1{alpha}-calcium handing pathway sheds new light on the role of PGC-1{alpha} in the therapy of cardiac diseases.

  8. Transgenic overexpression of Hdac3 in the heart produces increased postnatal cardiac myocyte proliferation but does not induce hypertrophy.

    Science.gov (United States)

    Trivedi, Chinmay M; Lu, Min Min; Wang, Qiaohong; Epstein, Jonathan A

    2008-09-26

    Class I and II histone deacetylases (HDACs) play vital roles in regulating cardiac development, morphogenesis, and hypertrophic responses. Although the roles of Hdac1 and Hdac2, class I HDACs, in cardiac hyperplasia, growth, and hypertrophic responsiveness have been reported, the role in the heart of Hdac3, another class I HDAC, has been less well explored. Here we report that myocyte-specific overexpression of Hdac3 in mice results in cardiac abnormalities at birth. Hdac3 overexpression produces thickening of ventricular myocardium, especially the interventricular septum, and reduction of both ventricular cavities in newborn hearts. Our data suggest that increased thickness of myocardium in Hdac3-transgenic (Hdac3-Tg) mice is due to increased cardiomyocyte hyperplasia without hypertrophy. Hdac3 overexpression inhibits several cyclin-dependent kinase inhibitors, including Cdkn1a, Cdkn1b, Cdkn1c, Cdkn2b, and Cdkn2c. Hdac3-Tg mice did not develop cardiac hypertrophy at 3 months of age, unlike previously reported Hdac2-Tg mice. Further, Hdac3 overexpression did not augment isoproterenol-induced cardiac hypertrophy when compared with wild-type littermates. These findings identify Hdac3 as a novel regulator of cardiac myocyte proliferation during cardiac development.

  9. Carbon nanotubes instruct physiological growth and functionally mature syncytia: nongenetic engineering of cardiac myocytes.

    Science.gov (United States)

    Martinelli, Valentina; Cellot, Giada; Toma, Francesca Maria; Long, Carlin S; Caldwell, John H; Zentilin, Lorena; Giacca, Mauro; Turco, Antonio; Prato, Maurizio; Ballerini, Laura; Mestroni, Luisa

    2013-07-23

    Myocardial tissue engineering currently represents one of the most realistic strategies for cardiac repair. We have recently discovered the ability of carbon nanotube scaffolds to promote cell division and maturation in cardiomyocytes. Here, we test the hypothesis that carbon nanotube scaffolds promote cardiomyocyte growth and maturation by altering the gene expression program, implementing the cell electrophysiological properties and improving networking and maturation of functional syncytia. In our study, we combine microscopy, biological and electrophysiological methodologies, and calcium imaging, to verify whether neonatal rat ventricular myocytes cultured on substrates of multiwall carbon nanotubes acquire a physiologically more mature phenotype compared to control (gelatin). We show that the carbon nanotube substrate stimulates the induction of a gene expression profile characteristic of terminal differentiation and physiological growth, with a 2-fold increase of α-myosin heavy chain (P carbon nanotubes appear to exert a protective effect against the pathologic stimulus of phenylephrine. Finally, cardiomyocytes on carbon nanotubes demonstrate a more mature electrophysiological phenotype of syncytia and intracellular calcium signaling. Thus, carbon nanotubes interacting with cardiomyocytes have the ability to promote physiological growth and functional maturation. These properties are unique in the current vexing field of tissue engineering, and offer unprecedented perspectives in the development of innovative therapies for cardiac repair.

  10. Mechanism for Muscarinic Inhibitory Regulation of the L-type Ca2 + Current in Cardiac Ventricular Myocytes

    Institute of Scientific and Technical Information of China (English)

    蒋彬; 杨向军; 惠杰; 蒋廷波; 宋建平; 刘志华

    2004-01-01

    @@ Objective The autonomic nervous system plays a key role in regulating cardiac function by modifying heart rate, contractility and impulse. The parasympathetic neurotransmitter acetyl-choline and muscarinic agonist carbachol (Cch) inhibit excitation-contraction coupling in cardiac ventricular myocytes. Muscarinic agonists suppress adenylyl cyclase (AC) acitivity and,by reducing activation of the cAMP/protein kinase A (PKA)cascade, inhibit the L-type Ca2+ current (ICa(L) ). They also increase the content of cGMP by stimulating guanylyl cyclase (GC) activity. The role of nitric oxide (NO)/cGMP in muscarinic inhibition has undergone considerable scrutiny. The role of the NO/cGMP pathway in the inhibition of ICa(L) by Cch was examined in guinea-pig ventricular myocytes.

  11. Down-regulation of replication factor C-40 (RFC40 causes chromosomal missegregation in neonatal and hypertrophic adult rat cardiac myocytes.

    Directory of Open Access Journals (Sweden)

    Hirotaka Ata

    Full Text Available BACKGROUND: Adult mammalian cardiac myocytes are generally assumed to be terminally differentiated; nonetheless, a small fraction of cardiac myocytes have been shown to replicate during ventricular remodeling. However, the expression of Replication Factor C (RFC; RFC140/40/38/37/36 and DNA polymerase δ (Pol δ proteins, which are required for DNA synthesis and cell proliferation, in the adult normal and hypertrophied hearts has been rarely studied. METHODS: We performed qRT-PCR and Western blot analysis to determine the levels of RFC and Pol δ message and proteins in the adult normal cardiac myocytes and cardiac fibroblasts, as well as in adult normal and pulmonary arterial hypertension induced right ventricular hypertrophied hearts. Immunohistochemical analyses were performed to determine the localization of the re-expressed DNA replication and cell cycle proteins in adult normal (control and hypertrophied right ventricle. We determined right ventricular cardiac myocyte polyploidy and chromosomal missegregation/aneuploidy using Fluorescent in situ hybridization (FISH for rat chromosome 12. RESULTS: RFC40-mRNA and protein was undetectable, whereas Pol δ message was detectable in the cardiac myocytes isolated from control adult hearts. Although RFC40 and Pol δ message and protein significantly increased in hypertrophied hearts as compared to the control hearts; however, this increase was marginal as compared to the fetal hearts. Immunohistochemical analyses revealed that in addition to RFC40, proliferative and mitotic markers such as cyclin A, phospho-Aurora A/B/C kinase and phospho-histone 3 were also re-expressed/up-regulated simultaneously in the cardiac myocytes. Interestingly, FISH analyses demonstrated cardiac myocytes polyploidy and chromosomal missegregation/aneuploidy in these hearts. Knock-down of endogenous RFC40 caused chromosomal missegregation/aneuploidy and decrease in the rat neonatal cardiac myocyte numbers. CONCLUSION: Our

  12. Gene Product Expression of Cyclin D2 and p16 During the Transition from Cardiac Myocyte Hyperplasia to Hypertrophy

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The current study was to investigate mRNA expression of cyclin D2 and p16 during the transition from cardiac myocyte hyperplasia to hypertrophy. Cultured cardiac myocytes (CM) and fibroblasts (FC) obtained from 1-day-old Sparague-Dawley rats were used in this study. We have determined (1) hyperplasia by cell growth curve and fluorescence activated cell sorting (FACS); and (2) ultrastructure by electron microscope observation; and (3) expressions of cyclin D2 mRNA and p16 mRNA by using in situ hybridization and image analysis. The results were shown (1) Results of cell growth curve and FACS analysis showed CM could proliferate in the first 3 cultured days (4 days in postnatal development). But the ability decreased quickly, concomitant with the differentiation. (2) The ultrastructure of CM showed the large amount of myofilaments and mitochondrion and FC showed moderate amount of rough endoplasmic reticulum. (3) The expression of cyclin D2 mRNA in 3-, 4-, 5-day CM group was 0.89 times(p<0.05), 0.80 times (p<0.05)and 0.56 times (p<0.01)of that in 1-day group respectively. P16 mRNA in 2-, 3-, 4-, 5-day CM group were 1.63 times(p<0.01),1.72 times(p<0.01),1.99 times (p<0.01)and 2.84 times (p<0.01) of that in 1-day group respectively. It can be concluded that cultured neonatal rat cardiac myocytes could proliferate during the first 3 cultured days, but the ability of proliferation decreased, from the fourth day, concomitant with differentiation. Cyclin D2 and p16 have the key roles during the transition from myocyte hyperplasia to hypertrophy.

  13. FAK-related nonkinase attenuates hypertrophy induced by angiotensin-Ⅱ in cultured neonatal rat cardiac myocytes

    Institute of Scientific and Technical Information of China (English)

    Jin QIN; Zheng-xiang LIU

    2006-01-01

    Aim: To examine the inhibitory effect of FAK-related nonkinase (FRNK) in cardiac hypertrophy in vitro and investigate the possible mechanisms. Methods: A functional fragment of FRNK cDNA was amplified by reverse transcription-polymerase chain reaction and cloned into the vector pcDNA3.1. Hypertrophy in neonatal rat cardiac myocytes was established with angiotensin-Ⅱ stimulation. The pcDNA3.1-FRNK or pcDNA3.1 was respectively transfected into cardiomyocytes by Lipofectamine 2000. The surface area and mRNA expression of atrial natriuretic peptide (ANP) of myocytes were employed to detect cardiac hypertrophy. NF-κB p65 protein in nuclear extracts, phosphorylation levels of ERK1/2 (p-ERK1/2) and AKT (p-AKT), as well as total ERK1/2, and AKT in variant treated cardiomyocytes were determined by Western blot. Results: Under the stimulation of angiotensin Ⅱ, the surface area of myocytes and levels of ANP mRNA were significantly increased. But transient transfection with pcDNA3.1-FRNK in advance may reduce the surface area and expression of ANP mRNA of hypertrophic myocytes. The protein levels of NF-κB p65 in nuclear extracts and p-ERK1/2, p-AKT in FRNK treated cardiomyocytes were significantly decreased compared with that in angiotensin-Ⅱ induced cardiomyocytes, while different treatments had little effect on total ERK1/2 and AKT. Conclusion: FRNK may inhibit angiotensin-Ⅱ-induced cardiomyocyte hypertrophy via decreasing phosphorylation levels at ERK1/2 and AKT, consequently downregulating nuclear translocation of NF-κB p65.

  14. Vagus nerve stimulation mitigates intrinsic cardiac neuronal and adverse myocyte remodeling postmyocardial infarction.

    Science.gov (United States)

    Beaumont, Eric; Southerland, Elizabeth M; Hardwick, Jean C; Wright, Gary L; Ryan, Shannon; Li, Ying; KenKnight, Bruce H; Armour, J Andrew; Ardell, Jeffrey L

    2015-10-01

    This paper aims to determine whether chronic vagus nerve stimulation (VNS) mitigates myocardial infarction (MI)-induced remodeling of the intrinsic cardiac nervous system (ICNS), along with the cardiac tissue it regulates. Guinea pigs underwent VNS implantation on the right cervical vagus. Two weeks later, MI was produced by ligating the ventral descending coronary artery. VNS stimulation started 7 days post-MI (20 Hz, 0.9 ± 0.2 mA, 14 s on, 48 s off; VNS-MI, n = 7) and was compared with time-matched MI animals with sham VNS (MI n = 7) vs. untreated controls (n = 8). Echocardiograms were performed before and at 90 days post-MI. At termination, IC neuronal intracellular voltage recordings were obtained from whole-mount neuronal plexuses. MI increased left ventricular end systolic volume (LVESV) 30% (P = 0.027) and reduced LV ejection fraction (LVEF) 6.5% (P < 0.001) at 90 days post-MI compared with baseline. In the VNS-MI group, LVESV and LVEF did not differ from baseline. IC neurons showed depolarization of resting membrane potentials and increased input resistance in MI compared with VNS-MI and sham controls (P < 0.05). Neuronal excitability and sensitivity to norepinephrine increased in MI and VNS-MI groups compared with controls (P < 0.05). Synaptic efficacy, as determined by evoked responses to stimulating input axons, was reduced in VNS-MI compared with MI or controls (P < 0.05). VNS induced changes in myocytes, consistent with enhanced glycogenolysis, and blunted the MI-induced increase in the proapoptotic Bcl-2-associated X protein (P < 0.05). VNS mitigates MI-induced remodeling of the ICNS, correspondingly preserving ventricular function via both neural and cardiomyocyte-dependent actions.

  15. Remodeling of the sarcomeric cytoskeleton in cardiac ventricular myocytes during heart failure and after cardiac resynchronization therapy.

    Science.gov (United States)

    Lichter, Justin G; Carruth, Eric; Mitchell, Chelsea; Barth, Andreas S; Aiba, Takeshi; Kass, David A; Tomaselli, Gordon F; Bridge, John H; Sachse, Frank B

    2014-07-01

    Sarcomeres are the basic contractile units of cardiac myocytes. Recent studies demonstrated remodeling of sarcomeric proteins in several diseases, including genetic defects and heart failure. Here we investigated remodeling of sarcomeric α-actinin in two models of heart failure, synchronous (SHF) and dyssynchronous heart failure (DHF), as well as a model of cardiac resynchronization therapy (CRT). We applied three-dimensional confocal microscopy and quantitative methods of image analysis to study isolated cells from our animal models. 3D Fourier analysis revealed a decrease of the spatial regularity of the α-actinin distribution in both SHF and DHF versus control cells. The spatial regularity of α-actinin in DHF cells was reduced when compared with SHF cells. The spatial regularity of α-actinin was partially restored after CRT. We found longitudinal depositions of α-actinin in SHF, DHF and CRT cells. These depositions spanned adjacent Z-disks and exhibited a lower density of α-actinin than in the Z-disk. Differences in the occurrence of depositions between the SHF, CRT and DHF models versus control were significant. Also, CRT cells exhibited a higher occurrence of depositions versus SHF, but not DHF cells. Other sarcomeric proteins did not accumulate in the depositions to the same extent as α-actinin. We did not find differences in the expression of α-actinin protein and its encoding gene in our animal models. In summary, our studies indicate that HF is associated with two different types of remodeling of α-actinin and only one of those was reversed after CRT. We suggest that these results can guide us to an understanding of remodeling of structures and function associated with sarcomeres.

  16. Contribution of NHE-1 to cell length cardiac shortening of normal and failing rabbit myocytes

    NARCIS (Netherlands)

    M.M.G.J. van Borren; J.G. Zegers; A. Baartscheer; J.H. Ravesloot

    2006-01-01

    At the same intracellular pH (pH(i)) Na+/H+ exchange (NHE-1) fluxes of ventricular myocytes of hypertrophied failing hearts (HFH) are increased. We assessed how NHE-1 affected cell length shortening. pH(i) was measured fluorimetrically in resting and twitching (1 - 3 Hz)normal and HFH rabbit myocyte

  17. Calcium response of KCl-excited populations of ventricular myocytes from the European sea bass (Dicentrarchus labrax): a promising approach to integrate cell-to-cell heterogeneity in studying the cellular basis of fish cardiac performance.

    Science.gov (United States)

    Ollivier, Hélène; Marchant, James; Le Bayon, Nicolas; Servili, Arianna; Claireaux, Guy

    2015-10-01

    Climate change challenges the capacity of fishes to thrive in their habitat. However, through phenotypic diversity, they demonstrate remarkable resilience to deteriorating conditions. In fish populations, inter-individual variation in a number of fitness-determining physiological traits, including cardiac performance, is classically observed. Information about the cellular bases of inter-individual variability in cardiac performance is scarce including the possible contribution of excitation-contraction (EC) coupling. This study aimed at providing insight into EC coupling-related Ca(2+) response and thermal plasticity in the European sea bass (Dicentrarchus labrax). A cell population approach was used to lay the methodological basis for identifying the cellular determinants of cardiac performance. Fish were acclimated at 12 and 22 °C and changes in intracellular calcium concentration ([Ca(2+)]i) following KCl stimulation were measured using Fura-2, at 12 or 22 °C-test. The increase in [Ca(2+)]i resulted primarily from extracellular Ca(2+) entry but sarcoplasmic reticulum stores were also shown to be involved. As previously reported in sea bass, a modest effect of adrenaline was observed. Moreover, although the response appeared relatively insensitive to an acute temperature change, a difference in Ca(2+) response was observed between 12- and 22 °C-acclimated fish. In particular, a greater increase in [Ca(2+)]i at a high level of adrenaline was observed in 22 °C-acclimated fish that may be related to an improved efficiency of adrenaline under these conditions. In conclusion, this method allows a rapid screening of cellular characteristics. It represents a promising tool to identify the cellular determinants of inter-individual variability in fishes' capacity for environmental adaptation.

  18. Design-based stereological estimation of the total number of cardiac myocytes in histological sections

    DEFF Research Database (Denmark)

    Brüel, Annemarie; Nyengaard, Jens Randel

    2005-01-01

    with antibodies against cadherin and type IV collagen to visualise the intercalated discs and the myocyte membranes, respectively. Using the physical disector in "local vertical windows" of the serial sections, the average number of nuclei per myocyte was estimated.RESULTS: The total number of myocyte nuclei...... in LV was 34.1 x 10(6) (0.08) (mean (coefficient of variation)), and the mean number of nuclei per myocyte 1.85 (0.03). Combining these estimates the total number of myocytes in LV was calculated to be 18.5 x 10(6) (0.09). CONCLUSIONS: This new method is applicable to a range of experiments focusing...

  19. Raisanberine protected pulmonary arterial rings and cardiac myocytes of rats against hypoxia injury by suppressing NADPH oxidase and calcium influx

    Institute of Scientific and Technical Information of China (English)

    Jie GAO; Yi-qun TANG; De-zai DAI; Yu-si CHENG; Guo-lin ZHANG; Can ZHANG; Yin DAI

    2012-01-01

    To investigate the protection of pulmonary arterial rings and cardiac myocytes of rats by raisanberine (RS),a derivative of berberine,against hypoxia injury and to elucidate the action mechanisms.Methods:Adult SD rats were exposed to intermittent hypoxia for 17 d or 28 d.The pulmonary arterial rings were isolated and vascular activity was measured using a transducer and computer-aided system.The difference in the tension produced by phenylephrine in the presence and absence of L-nitroarginine (10 μmol/L) was referred to as the NO bioavailability; the maximum release of NO was assessed by the ratio of the maximal dilatation caused by ACh to those caused by sodium nitroprusside.After the lungs were fixed,the internal and the external diameters of the pulmonary arterioles were measured using a graphic analysis system.Cultured cardiac myocytes from neonatal rats were exposed to H2O2 (10 μmol/L) to mimic hypoxia injury.ROS generation and [Ca2+]i level in the myocytes were measured using DHE and Fluo-3 fluorescence,respectively.Results:Oral administration of RS (80 mg/kg),the NADPH oxidase inhibitor apocynin (APO,80 mg/kg) or Ca2+ channel blocker nifedipine (Nif,10 mg/kg,) significantly alleviated the abnormal increase in the vasoconstriction force and endothelium-related vasodilatation induced by the intermittent hypoxia.The intermittent hypoxia markedly decreased the NO bioavailability and maximal NO release from pulmonary arterial rings,which were reversed by APO or RS administration.However,RS administration did not affect the NO bioavailability and maximal NO release from pulmonary arterial rings of normal rats.RS,Nif or APO administration significantly attenuated the pulmonary arteriole remodeling.Treatment of cultured cardiac myocytes with RS (10 μmol/L) suppressed the ROS generation and [Ca2+]i increase induced by H2O2,which were comparable to those caused by APO (10 μmol/L) or Nif (0.1 μmol/L).Conclusion:Raisanberine relieved hypoxic/oxidant insults to the

  20. Temperature dependence of intracellular free calcium in cardiac myocytes from rat and ground squirrel measured by confocal microscopy

    Institute of Scientific and Technical Information of China (English)

    王世强; 周曾铨; 钱洪

    1999-01-01

    The temperature-dependence of infraeeliular free caleimn (Ca) was investigated in mdo-1 loaded ventricular myocytes from the ral, a non-hibernator, and from the ground squirrel, a hibernator. The dissociation constant of indo-l at different temperatures was calibrated both al pll-tat and at @-stat . and the result demonstrated that the @-stat ralibration should be prettrred . Analysis of the fluoreseent image showed a striking increase of Ca2 as well as spontaneous caleiuni waves in ral cells, indicating an overloaded cakuum. In contrast, cardiac myocytes of the ground sqnirraf were found to keep a constant (Ca2+) without caleium overload regardless of temperature variation. It is be-lieved that understanding of the mechanisms underlying the interccllular caleima homeostasis of hibrernators may lead to solutions of some medical questions .

  1. Intermittent hypoxia attenuates ischemia/reperfusion induced apoptosis in cardiac myocytes via regulating Bcl-2/Bax expression

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Intermittent hypoxia has been shown to provide myocardial protection against ishemia/reperfusion-induced injury.Cardiac myocyte loss through apoptosis has been reported in ischemia/reperfusion injury. Our aim was to investigate whether intermittent hypoxia could attenuate ischemia/reperfusion-induced apoptosis in cardiac myocytes and its potential mechanisms. Adult male Sprague-Dawley rats were exposed to hypoxia simulated 5000 m in a hypobaric chamber for 6 h/day, lasting 42 days. Normoxia group rats were kept under normoxic conditions. Isolated perfused hearts from both groups were subjected to 30 min of global ischemia followed by 60 min reperfusion.Incidence of apoptosis in cardiac myocytes was determined by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and DNA agarose gel electrophoresis. Expressions of apoptosis related proteins,Bax and Bcl-2, in cytosolic and membrane fraction were detected by Western Blotting. After ischemia/reperfusion,enhanced recovery of cardiac function was observed in intermittent hypoxia hearts compared with normoxia group.Ischemia/reperfusion-induced apoptosis, as evidenced by TUNEL-positive nuclei and DNA fragmentation, was significantly reduced in intermittent hypoxia group compared with normoxia group. After ischemia/reperfusion,expression of Bax in both cytosolic and membrane fractions was decreased in intermittent hypoxia hearts compared with normoxia group. Although ischemia/reperfusion did not induce changes in the level of Bcl-2 expression in cytosolic fraction between intermittent hypoxia and normoxia groups, the expression of Bcl-2 in membrane fraction was upregulated in intermittent hypoxia group compared with normoxia group. These results indicated that the cardioprotection of intermittent hypoxia against ischemia/reperfusion injury appears to be in part due to reduce myocardial apoptosis. Intermittent hypoxia attenuated ischemia/reperfusion-induced apoptosis via increasing the ratio of Bcl

  2. Role of NF-κB in protection of EPO pretreatment on neonatal rat cardiac myocytes with hypoxia/reoxygenation injury

    Institute of Scientific and Technical Information of China (English)

    QIN Chuan; XIAO Ying-bin; ZHONG Qian-jin; CHEN Lin; WANG Xue-feng

    2005-01-01

    Objective:To observe the protective effects of erythropoietin (EPO) pretreatment on cardiac myocyte with hypoxia/reoxygenation (H/R) injury and the role of NF-κB in this effects. Methods:After the H/R model of cardiac myocytes of neonatal rats was established, the cultured cardiac myocytes were divided into 4 groups, including EPO pretreatment group ( EPO 10 U/ml 24 h before H/R), EPO pretreatment + PDTC group( EPO 10 U/ml and PDTC 5 μg/ml 24 h before H/R), PDTC group (PDTC 5 μg /ml 24 h before H/R) and control group. Before and after the H/R, assay of LDH concentration in the culture medium, the survival rate of the myocytes tested by MTT chromatometry and the apoptosis by flow cytometry were undertaken. Activation of NF-κB was determined by EMSA before and after H/R. Results:EPO pretreatment markedly reduced the LDH concentration in the medium, elevated the survival rate of myocytes and inhibited the apoptosis after H/R. Addition of PDTC during the pretreatment abolished the protective effects of EPO pretreatment. NF-κB was markedly activated during EPO pretreatment and PDTC inhibited the activation. However, after H/R, the activity of NF-κB in myocytes with EPO pretreatment was significantly inhibited compared to the other myocytes. Conclusion:NF-κB is significantly activated during EPO pretreatment, but is inhibited after H/R, which is correlated with the protective effects of EPO pretreatment on cardiac myocytes with H/R. This phenomenon can be explained as the negative feedback mechanism of the activation of NF-κB.

  3. Statistical Metamodeling and Sequential Design of Computer Experiments to Model Glyco-Altered Gating of Sodium Channels in Cardiac Myocytes.

    Science.gov (United States)

    Du, Dongping; Yang, Hui; Ednie, Andrew R; Bennett, Eric S

    2016-09-01

    Glycan structures account for up to 35% of the mass of cardiac sodium ( Nav ) channels. To question whether and how reduced sialylation affects Nav activity and cardiac electrical signaling, we conducted a series of in vitro experiments on ventricular apex myocytes under two different glycosylation conditions, reduced protein sialylation (ST3Gal4(-/-)) and full glycosylation (control). Although aberrant electrical signaling is observed in reduced sialylation, realizing a better understanding of mechanistic details of pathological variations in INa and AP is difficult without performing in silico studies. However, computer model of Nav channels and cardiac myocytes involves greater levels of complexity, e.g., high-dimensional parameter space, nonlinear and nonconvex equations. Traditional linear and nonlinear optimization methods have encountered many difficulties for model calibration. This paper presents a new statistical metamodeling approach for efficient computer experiments and optimization of Nav models. First, we utilize a fractional factorial design to identify control variables from the large set of model parameters, thereby reducing the dimensionality of parametric space. Further, we develop the Gaussian process model as a surrogate of expensive and time-consuming computer models and then identify the next best design point that yields the maximal probability of improvement. This process iterates until convergence, and the performance is evaluated and validated with real-world experimental data. Experimental results show the proposed algorithm achieves superior performance in modeling the kinetics of Nav channels under a variety of glycosylation conditions. As a result, in silico models provide a better understanding of glyco-altered mechanistic details in state transitions and distributions of Nav channels. Notably, ST3Gal4(-/-) myocytes are shown to have higher probabilities accumulated in intermediate inactivation during the repolarization and yield a

  4. Enhanced effect of VEGF165 on L-type calcium currents in guinea-pig cardiac ventricular myocytes.

    Science.gov (United States)

    Xing, Wenlu; Gao, Chuanyu; Qi, Datun; Zhang, You; Hao, Peiyuan; Dai, Guoyou; Yan, Ganxin

    2017-01-01

    The mechanisms of vascular endothelial growth factor 165 (VEGF165) on electrical properties of cardiomyocytes have not been fully elucidated. The aim of this study is to test the hypothesis that VEGF165, an angiogenesis-initiating factor, affects L-type calcium currents (ICa,L) and cell membrane potential in cardiac myocytes by acting on VEGF type-2 receptors (VEGFR2). ICa,L and action potentials (AP) were recorded by the whole-cell patch clamp method in isolated guinea-pig ventricular myocytes treated with different concentrations of VEGF165 proteins. Using a VEGFR2 inhibitor, we also tested the receptor of VEGF165 in cardiomyocytes. We found that VEGF165 increased ICa,L in a concentration-dependent manner. SU5416, a VEGFR2 inhibitor, almost completely eliminated VEGF165-induced ICa,L increase. VEGF165 had no significant influence on action potential 90 (APD90) and other properties of AP. We conclude that in guinea-pig ventricular myocytes, ICa,L can be increased by VEGF165 in a concentration-dependent manner through binding to VEGFR2 without causing any significant alteration to action potential duration. Results of this study may further expound the safety of VEGF165 when used in the intervention of heart diseases.

  5. Integrative systems models of cardiac excitation-contraction coupling.

    Science.gov (United States)

    Greenstein, Joseph L; Winslow, Raimond L

    2011-01-07

    Excitation-contraction coupling in the cardiac myocyte is mediated by a number of highly integrated mechanisms of intracellular Ca²(+) transport. The complexity and integrative nature of heart cell electrophysiology and Ca²(+) cycling has led to an evolution of computational models that have played a crucial role in shaping our understanding of heart function. An important emerging theme in systems biology is that the detailed nature of local signaling events, such as those that occur in the cardiac dyad, have important consequences at higher biological scales. Multiscale modeling techniques have revealed many mechanistic links between microscale events, such as Ca²(+) binding to a channel protein, and macroscale phenomena, such as excitation-contraction coupling gain. Here, we review experimentally based multiscale computational models of excitation-contraction coupling and the insights that have been gained through their application.

  6. Effects of adiponectin on oxidative stress and apoptosis in human cardiac myocytes cultured with high glucose

    Institute of Scientific and Technical Information of China (English)

    LI Xing; LI Mei-rong; GUO Zhi-xin

    2012-01-01

    Background Diabetic cardiomyopathy is the major cause of morbidity and mortality in diabetic patients.Oxidative stress plays an important role in diabetic cardiomyopathy.This study aimed to investigate the effects of adiponectin on oxidative stress and apoptosis in human cardiac myocytes (HCM) cultured with high glucose.Methods The cells were assigned to three group: control group,high glucose group and high glucose plus adiponectin group.After culture for 24,48,72 hours,oxidative stress was evaluated by detecting levels of malondialdehyde (MDA)and superoxide dismutase (SOD) in the supernatant of culture media.The expression of p66Shc and Heme oxygenase-1 (HO-1) was detected by real-time polymerase chain reaction (PCR).Flow cytometry was designed to observe and detect cellular apoptosis.Results Our findings showed significant increase in MDA levels and decrease in SOD activity in the high glucose group compared with the control group (P <0.05).However,MDA levels were significantly decreased and SOD activity was significantly increased in the adiponectin group compared with those in the high-glucose group (P <0.05).The mRNA expression of HO-1 in the high glucose group was significantly increased in a time-dependent manner compared with that in the control group (P <0.05).Adiponectin further increased the mRNA expression of HO-1 induced by high glucose in a time-dependent manner (P <0.05).The expression of p66Shc was significantly increased in high glucose group compared with that in the control group (P <0.05).Adiponectin significantly suppressed the upregulation of p66Shc induced by high glucose (P <0.05).The apoptotic rate of cardiomyocytes was significantly increased in the high glucose group compared with that in the control group while the apoptotic rate in the adiponectin group was remarkably declined in comparison with that in the high glucose group.Conclusion Adiponectin reduces high glucose-induced oxidative stress and apoptosis and plays a

  7. Recording of calcium transient and analysis of calcium removal mechanisms in cardiac myocytes from rats and ground squirrels

    Institute of Scientific and Technical Information of China (English)

    王世强; 周曾铨; 钱洪

    2000-01-01

    With confocal microscopy, we recorded calcium transients and analyzed calcium removal rate at different temperatures in cardiac myocytes from the rat, a non-hibernator, and the ground squirrel, a hibernator. The results showed a remarkable increase of the diastolic level of calcium transients in the rat but no detectable change in the ground squirrel. Calcium transient of the ground squirrel, compared with that of the rat at the same temperature, had a shorter duration and showed a faster calcium removal. As indicated by the pharmacological effect of cyclopiazonic acid, calcium uptake by sarcoplasmic reticulum (SR) was the major mechanism of calcium removal, and was faster in the ground squirrel than in the rat. Our results confirmed the essential role of SR in hypothermia-tolerant adaptation, and negated the importance of Na-Ca exchange. We postulated the possibility to improve hypothermia-tolerance of the cardiac tissue of non-hibernating mammals.

  8. Image Processing Techniques for Assessing Contractility in Isolated Neonatal Cardiac Myocytes

    Directory of Open Access Journals (Sweden)

    Carlos Bazan

    2011-01-01

    employed in determining myocyte contractility almost simultaneously with the acquisition of the Ca2+ transient and other correlates of cell contraction. The proposed methodology can be utilized to evaluate changes in contractile behavior resulting from drug intervention, disease models, transgeneity, or other common applications of neonatal cardiocytes.

  9. Angiotensin II type 1 receptor signalling regulates microRNA differentially in cardiac fibroblasts and myocytes

    DEFF Research Database (Denmark)

    Jeppesen, Pia Lindgren; Christensen, Gitte Lund; Schneider, Mikael

    2011-01-01

    Background and purpose: The Angiotensin II type 1 receptor (AT(1) R) is a key regulator of blood pressure and cardiac contractility and is profoundly involved in development of cardiac disease. Since several microRNAs (miRNAs) have been implicated in cardiac disease, we asked whether miRNAs might...

  10. Carbon Nanohorns Promote Maturation of Neonatal Rat Ventricular Myocytes and Inhibit Proliferation of Cardiac Fibroblasts: a Promising Scaffold for Cardiac Tissue Engineering

    Science.gov (United States)

    Wu, Yujing; Shi, Xiaoli; Li, Yi; Tian, Lei; Bai, Rui; Wei, Yujie; Han, Dong; Liu, Huiliang; Xu, Jianxun

    2016-06-01

    Cardiac tissue engineering (CTE) has developed rapidly, but a great challenge remains in finding practical scaffold materials for the construction of engineered cardiac tissues. Carbon nanohorns (CNHs) may be a potential candidate due to their special structure and properties. The purpose of this study was to assess the effect of CNHs on the biological behavior of neonatal rat ventricular myocytes (NRVMs) for CTE applications. CNHs were incorporated into collagen to form growth substrates for NRVMs. Transmission electron microscopy (TEM) observations demonstrated that CNHs exhibited a good affinity to collagen. Moreover, it was found that CNH-embedded substrates enhanced adhesion and proliferation of NRVMs. Immunohistochemical staining, western blot analysis, and intracellular calcium transient measurements indicated that the addition of CNHs significantly increased the expression and maturation of electrical and mechanical proteins (connexin-43 and N-cadherin). Bromodeoxyuridine staining and a Cell Counting Kit-8 assay showed that CNHs have the ability to inhibit the proliferation of cardiac fibroblasts. These findings suggest that CNHs can have a valuable effect on the construction of engineered cardiac tissues and may be a promising scaffold for CTE.

  11. Ca(2+ release events in cardiac myocytes up close: insights from fast confocal imaging.

    Directory of Open Access Journals (Sweden)

    Vyacheslav M Shkryl

    Full Text Available The spatio-temporal properties of Ca(2+ transients during excitation-contraction coupling and elementary Ca(2+ release events (Ca(2+ sparks were studied in atrial and ventricular myocytes with ultra-fast confocal microscopy using a Zeiss LSM 5 LIVE system that allows sampling rates of up to 60 kHz. Ca(2+ sparks which originated from subsarcolemmal junctional sarcoplasmic reticulum (j-SR release sites in atrial myocytes were anisotropic and elongated in the longitudinal direction of the cell. Ca(2+ sparks in atrial cells originating from non-junctional SR and in ventricular myocytes were symmetrical. Ca(2+ spark recording in line scan mode at 40,000 lines/s uncovered step-like increases of [Ca(2+]i. 2-D imaging of Ca(2+ transients revealed an asynchronous activation of release sites and allowed the sequential recording of Ca(2+ entry through surface membrane Ca(2+ channels and subsequent activation of Ca(2+-induced Ca(2+ release. With a latency of 2.5 ms after application of an electrical stimulus, Ca(2+ entry could be detected that was followed by SR Ca(2+ release after an additional 3 ms delay. Maximum Ca(2+ release was observed 4 ms after the beginning of release. The timing of Ca(2+ entry and release was confirmed by simultaneous [Ca(2+]i and membrane current measurements using the whole cell voltage-clamp technique. In atrial cells activation of discrete individual release sites of the j-SR led to spatially restricted Ca(2+ release events that fused into a peripheral ring of elevated [Ca(2+]i that subsequently propagated in a wave-like fashion towards the center of the cell. In ventricular myocytes asynchronous Ca(2+ release signals from discrete sites with no preferential subcellular location preceded the whole-cell Ca(2+ transient. In summary, ultra-fast confocal imaging allows investigation of Ca(2+ signals with a time resolution similar to patch clamp technique, however in a less invasive fashion.

  12. Effect of cardiac glycosides on action potential characteristics and contractility in cat ventricular myocytes: role of calcium overload.

    Science.gov (United States)

    Ruch, Stuart R; Nishio, Manabu; Wasserstrom, J Andrew

    2003-10-01

    There is increasing evidence that cardiac glycosides act through mechanisms distinct from inhibition of the sodium pump but which may contribute to their cardiac actions. To more fully define differences between agents indicative of multiple sites of action, we studied changes in contractility and action potential (AP) configuration in cat ventricular myocytes produced by six cardiac glycosides (ouabain, ouabagenin, dihydroouabain, actodigin, digoxin, and resibufogenin). AP shortening was observed only with ouabain and actodigin. There was extensive inotropic variability between agents, with some giving full inotropic effects before automaticity occurred whereas others produced minimal inotropy before toxicity. AP shortening was not a result of alterations in calcium current or the inward rectifier potassium current, but correlated with an increase in steady-state outward current (Iss), which was sensitive to KB-R7943, a Na+-Ca2+ exchange (NCX) inhibitor. Interestingly, Iss was observed following exposure to ouabain and dihydroouabain, suggesting that an additional mechanism is operative with dihydroouabain that prevents AP shortening. Further investigation into differences in inotropy between ouabagenin, dihydroouabain and ouabain revealed almost identical responses under AP voltage clamp. Thus all agents appear to act on the sodium pump and thereby secondarily increase the outward reverse mode NCX current, but the extent of AP duration shortening and positive inotropy elicited by each agent is limited by development of their toxic actions. The quantitative differences between cardiac glycosides suggest that mechanisms independent of sodium pump inhibition may result from an altered threshold for calcium overload possibly involving direct or indirect effects on calcium release from the sarcoplasmic reticulum.

  13. Automatic quantitative analysis of t-tubule organization in cardiac myocytes using ImageJ.

    Science.gov (United States)

    Pasqualin, Côme; Gannier, François; Malécot, Claire O; Bredeloux, Pierre; Maupoil, Véronique

    2015-02-01

    The transverse tubule system in mammalian striated muscle is highly organized and contributes to optimal and homogeneous contraction. Diverse pathologies such as heart failure and atrial fibrillation include disorganization of t-tubules and contractile dysfunction. Few tools are available for the quantification of the organization of the t-tubule system. We developed a plugin for the ImageJ/Fiji image analysis platform developed by the National Institutes of Health. This plugin (TTorg) analyzes raw confocal microscopy images. Analysis options include the whole image, specific regions of the image (cropping), and z-axis analysis of the same image. Batch analysis of a series of images with identical criteria is also one of the options. There is no need to either reorientate any specimen to the horizontal or to do a thresholding of the image to perform analysis. TTorg includes a synthetic "myocyte-like" image generator to test the plugin's efficiency in the user's own experimental conditions. This plugin was validated on synthetic images for different simulated cell characteristics and acquisition parameters. TTorg was able to detect significant differences between the organization of the t-tubule systems in experimental data of mouse ventricular myocytes isolated from wild-type and dystrophin-deficient mice. TTorg is freely distributed, and its source code is available. It provides a reliable, easy-to-use, automatic, and unbiased measurement of t-tubule organization in a wide variety of experimental conditions.

  14. P2X4 receptor–eNOS signaling pathway in cardiac myocytes as a novel protective mechanism in heart failure

    Directory of Open Access Journals (Sweden)

    Ronghua Yang

    2015-01-01

    Full Text Available We have demonstrated using immunoprecipitation and immunostaining a novel physical association of the P2X4 receptor (P2X4R, a ligand-gated ion channel, with the cardioprotective, calcium-dependent enzyme endothelial nitric oxide synthase (eNOS. Treatment of murine ventricular myocytes with the P2XR agonist 2-methylthioATP (2-meSATP to induce a current (mainly Na+ increased the formation of nitric oxide (NO, as measured using a fluorescent probe. Possible candidates for downstream effectors mediating eNOS activity include cyclic GMP and PKG or cellular protein nitrosylation. A cardiac-specific P2X4R overexpressing mouse line was protected from heart failure (HF with improved cardiac function and survival in post-infarct, pressure overload, and calsequestrin (CSQ overexpression models of HF. Although the role of the P2X4R in other tissues such as the endothelium and monocytes awaits characterization in tissue-specific KO, cardiac-specific activation of eNOS may be more cardioprotective than an increased activity of global systemic eNOS. The intra-myocyte formation of NO may be more advantageous over NO derived externally from a donor. A small molecule drug stimulating this sarcolemmal pathway or gene therapy-mediated overexpression of the P2X4R in cardiac myocytes may represent a new therapy for both ischemic and pressure overloaded HF.

  15. P2X4 receptor–eNOS signaling pathway in cardiac myocytes as a novel protective mechanism in heart failure

    Science.gov (United States)

    Yang, Ronghua; Beqiri, Dardan; Shen, Jian-Bing; Redden, John M.; Dodge-Kafka, Kimberly; Jacobson, Kenneth A.; Liang, Bruce T.

    2014-01-01

    We have demonstrated using immunoprecipitation and immunostaining a novel physical association of the P2X4 receptor (P2X4R), a ligand-gated ion channel, with the cardioprotective, calcium-dependent enzyme endothelial nitric oxide synthase (eNOS). Treatment of murine ventricular myocytes with the P2XR agonist 2-methylthioATP (2-meSATP) to induce a current (mainly Na+) increased the formation of nitric oxide (NO), as measured using a fluorescent probe. Possible candidates for downstream effectors mediating eNOS activity include cyclic GMP and PKG or cellular protein nitrosylation. A cardiac-specific P2X4R overexpressing mouse line was protected from heart failure (HF) with improved cardiac function and survival in post-infarct, pressure overload, and calsequestrin (CSQ) overexpression models of HF. Although the role of the P2X4R in other tissues such as the endothelium and monocytes awaits characterization in tissue-specific KO, cardiac-specific activation of eNOS may be more cardioprotective than an increased activity of global systemic eNOS. The intra-myocyte formation of NO may be more advantageous over NO derived externally from a donor. A small molecule drug stimulating this sarcolemmal pathway or gene therapy-mediated overexpression of the P2X4R in cardiac myocytes may represent a new therapy for both ischemic and pressure overloaded HF. PMID:25750695

  16. Inhibition of PKR protects against H2O2-induced injury on neonatal cardiac myocytes by attenuating apoptosis and inflammation

    Science.gov (United States)

    Wang, Yongyi; Men, Min; Xie, Bo; Shan, Jianggui; Wang, Chengxi; Liu, Jidong; Zheng, Hui; Yang, Wengang; Xue, Song; Guo, Changfa

    2016-01-01

    Reactive oxygenation species (ROS) generated from reperfusion results in cardiac injury through apoptosis and inflammation, while PKR has the ability to promote apoptosis and inflammation. The aim of the study was to investigate whether PKR is involved in hydrogen peroxide (H2O2) induced neonatal cardiac myocytes (NCM) injury. In our study, NCM, when exposed to H2O2, resulted in persistent activation of PKR due to NCM endogenous RNA. Inhibition of PKR by 2-aminopurine (2-AP) or siRNA protected against H2O2 induced apoptosis and injury. To elucidate the mechanism, we revealed that inhibition of PKR alleviated H2O2 induced apoptosis companied by decreased caspase3/7 activity, BAX and caspase-3 expression. We also revealed that inhibition of PKR suppressed H2O2 induced NFκB pathway and NLRP3 activation. Finally, we found ADAR1 mRNA and protein expression were both induced after H2O2 treatment through STAT-2 dependent pathway. By gain and loss of ADAR1 expression, we confirmed ADAR1 modulated PKR activity. Therefore, we concluded inhibition of PKR protected against H2O2-induced injury by attenuating apoptosis and inflammation. A self-preservation mechanism existed in NCM that ADAR1 expression is induced by H2O2 to limit PKR activation simultaneously. These findings identify a novel role for PKR/ADAR1 in myocardial reperfusion injury. PMID:27929137

  17. Re-evaluation of the action potential upstroke velocity as a measure of the Na+ current in cardiac myocytes at physiological conditions.

    Directory of Open Access Journals (Sweden)

    Géza Berecki

    Full Text Available BACKGROUND: The SCN5A encoded sodium current (I(Na generates the action potential (AP upstroke and is a major determinant of AP characteristics and AP propagation in cardiac myocytes. Unfortunately, in cardiac myocytes, investigation of kinetic properties of I(Na with near-physiological ion concentrations and temperature is technically challenging due to the large amplitude and rapidly activating nature of I(Na, which may seriously hamper the quality of voltage control over the membrane. We hypothesized that the alternating voltage clamp-current clamp (VC/CC technique might provide an alternative to traditional voltage clamp (VC technique for the determination of I(Na properties under physiological conditions. PRINCIPAL FINDINGS: We studied I(Na under close-to-physiological conditions by VC technique in SCN5A cDNA-transfected HEK cells or by alternating VC/CC technique in both SCN5A cDNA-transfected HEK cells and rabbit left ventricular myocytes. In these experiments, peak I(Na during a depolarizing VC step or maximal upstroke velocity, dV/dt(max, during VC/CC served as an indicator of available I(Na. In HEK cells, biophysical properties of I(Na, including current density, voltage dependent (inactivation, development of inactivation, and recovery from inactivation, were highly similar in VC and VC/CC experiments. As an application of the VC/CC technique we studied I(Na in left ventricular myocytes isolated from control or failing rabbit hearts. CONCLUSIONS: Our results demonstrate that the alternating VC/CC technique is a valuable experimental tool for I(Na measurements under close-to-physiological conditions in cardiac myocytes.

  18. Measurement of Strain in Cardiac Myocytes at Micrometer Scale Based on Rapid Scanning Confocal Microscopy and Non-Rigid Image Registration.

    Science.gov (United States)

    Lichter, J; Li, Hui; Sachse, Frank B

    2016-10-01

    Measurement of cell shortening is an important technique for assessment of physiology and pathophysiology of cardiac myocytes. Many types of heart disease are associated with decreased myocyte shortening, which is commonly caused by structural and functional remodeling. Here, we present a new approach for local measurement of 2-dimensional strain within cells at high spatial resolution. The approach applies non-rigid image registration to quantify local displacements and Cauchy strain in images of cells undergoing contraction. We extensively evaluated the approach using synthetic cell images and image sequences from rapid scanning confocal microscopy of fluorescently labeled isolated myocytes from the left ventricle of normal and diseased canine heart. Application of the approach yielded a comprehensive description of cellular strain including novel measurements of transverse strain and spatial heterogeneity of strain. Quantitative comparison with manual measurements of strain in image sequences indicated reliability of the developed approach. We suggest that the developed approach provides researchers with a novel tool to investigate contractility of cardiac myocytes at subcellular scale. In contrast to previously introduced methods for measuring cell shorting, the developed approach provides comprehensive information on the spatio-temporal distribution of 2-dimensional strain at micrometer scale.

  19. Alterations in intracellular ionic calcium levels in isolated adult rat cardiac myocytes due to the generation of free radicals

    Energy Technology Data Exchange (ETDEWEB)

    Burton, K.P.; Nazeran, H.; Hagler, H.K. (Univ. of Texas, Dallas, TX (United States))

    1991-03-15

    Oxygen-derived free radical production has been documented to occur on reperfusion of the ischemic myocardium. Intracellular ionic calcium ((Ca{sup ++}){sub i}) levels in isolated adult rat cardiac myocytes (M) exposed to free radicals were evaluated using the fluorescent calcium indicator, fura-2. The effect of different time periods of free radical exposure and the level of extracellular Ca{sup ++} concentration on altering (Ca{sup ++}){sub i} was examined. The free radical generating system (FRGS) utilized consisted of a HEPES buffered physiological salt solution containing 2.3 mM purine, 2.4. {mu}M iron-loaded transferrin and 0.01 U/ml xanthine oxidase. M maintained in HEPES buffer or the HEPES buffer containing purine and iron-loaded transferrin continued to stimulate, exhibited relatively uniform 340/380 ratios and maintained a rod shape for extended time periods. M continuously exposed to the FRGS showed a significant increase in (Ca{sup ++}){sub i}, became unresponsive to stimulation at 31 {plus minus} 7 (SE) min and eventually exhibited contracture. Exposure to the FRGS for 10 min resulted in a response similar to continuous exposure. M exposed to the FRGS for 5 min exhibited regular Ca{sup ++} transients for 55{plus minus}5 min. M exposed to the FRGS for 10 min and maintained in 2.5 mM Ca{sup ++} versus 1.25 mM Ca{sup ++}, accumulated significantly higher (CA{sup ++}){sub i}. Quiescent myocytes continuously exposed to the FRGS also exhibited a significant increase in (Ca{sup ++}){sub i} over time. Thus, a brief period of free radical exposure may induce subsequent damage. Alterations in Ca{sup ++} flux resulting from the generation of free radicals may possibly contribute to the development of Ca{sup ++} overload and myocardial arrhythmias.

  20. Inhibitory effect of antisense oligodeoxynucleotide to p44/p42 MAPK on angiotensin II-induced hypertrophic response in cultured neonatal rat cardiac myocyte

    Institute of Scientific and Technical Information of China (English)

    Shi-qinZHANG; BoDING; Zhao-guiGUO; Yun-xiaLI

    2004-01-01

    AIM: To explore the inhibitory effect of antisense oligonucleotide (ODN) to mitogen activated protein kinase(MAPK) on cardiomyocyte hypertrophy induced by angiotensin Ⅱ (Ang Ⅱ). METHODS: A 17-mer phosphorothioate-protected antisense ODN directed against the initiation of translation sites of the p42 and p44 MAPK isoforms byliposomal transfection was applied to inhibit the translation of p44/p42 MAPK mRNA. The sense and random ODNs to p44/p42MAPK were used as sequence controls. Neonatal cardiac myocytes were exposed to Ang Ⅱ (10nmol/L) for 5 min and then harvested in lysis buffer for the measurement of the activity and the phosphorylated protein content of p44/p42MAPK that were tested by P-81 phosphocellulose filter paper method and Western blotting, respectively. The rate of protein synthesis by [3H]leucine incorporation and the diameter of cell were measured after exposure to Ang Ⅱ for 24 h and 72 h, respectively. RESULTS: In cardiac myocyte Ang Ⅱ increased p44/p42MAPK activity and phosphorylated protein content by 140 % and 699 %, and also increased [3H]leucine incorporation and cell diameter by 40 % and 27 %. c-fos and c-myc mRNAs were induced significantly after exposure to Ang Ⅱ. Antisense ODN to p44/p42MAPK (0.2 μmol/L) reduced Ang Ⅱ-induced MAPK activity by 30 %,and phophorylated MAPK protein expression by 59 % in cardiac myocyte, and inhibited c-fos and c-myc mRNA expression induced by Ang Ⅱ by 44 % and 43 %, respectively. The diameter and the rate of protein synthesis of cardiac myocyte induced by Ang Ⅱ were decreased by 16 % and 22 % after pretreatment with antisense ODN to p44/p42MAPK. CONCLUSION: Antisense ODN to p44/p42 MAPK inhibited the increase of rate of protein synthesis,and the augmentation of cell diameter and expression of c-fos and c-myc mRNA induced by Ang Ⅱ in culturedcardiac myocytes, p44/p42 MAPK played a critical role in the hypertrophic response induced by Ang Ⅱ in cultured neonatal rat cardiac myocytes.

  1. Effects of antibiotics on the contractility and Ca2+ transients of rat cardiac myocytes.

    Science.gov (United States)

    Belus, A; White, E

    2001-01-26

    We have compared the effects of streptomycin sulphate, gentamicin sulphate and neomycin sulphate on cell shortening (our index of contractility) and intracellular Ca2+ ([Ca2+](i)) transients of rat ventricular myocytes. All three agents abolished shortening and [Ca2+](i), transients but streptomycin was significantly less potent than the other agents. The IC(50) of streptomycin was 0.37 mM for shortening and 0.78 mM for [Ca2+](i), approximately an order of magnitude greater than equivalent values for gentamicin and neomycin. Gentamicin and streptomycin shortened the action potential duration of most cells but prolonged the action potential duration of others. We therefore conclude that multiple ionic mechanisms affecting action potential duration are modulated by these antibiotics. Our observations are consistent with the negative inotropic effect of antibiotics being caused by a decrease in Ca2+ influx causing a reduction in the [Ca2+](i) transient.

  2. A device for rapid and quantitative measurement of cardiac myocyte contractility

    Science.gov (United States)

    Gaitas, Angelo; Malhotra, Ricky; Li, Tao; Herron, Todd; Jalife, José

    2015-03-01

    Cardiac contractility is the hallmark of cardiac function and is a predictor of healthy or diseased cardiac muscle. Despite advancements over the last two decades, the techniques and tools available to cardiovascular scientists are limited in their utility to accurately and reliably measure the amplitude and frequency of cardiomyocyte contractions. Isometric force measurements in the past have entailed cumbersome attachment of isolated and permeabilized cardiomyocytes to a force transducer followed by measurements of sarcomere lengths under conditions of submaximal and maximal Ca2+ activation. These techniques have the inherent disadvantages of being labor intensive and costly. We have engineered a micro-machined cantilever sensor with an embedded deflection-sensing element that, in preliminary experiments, has demonstrated to reliably measure cardiac cell contractions in real-time. Here, we describe this new bioengineering tool with applicability in the cardiovascular research field to effectively and reliably measure cardiac cell contractility in a quantitative manner. We measured contractility in both primary neonatal rat heart cardiomyocyte monolayers that demonstrated a beat frequency of 3 Hz as well as human embryonic stem cell-derived cardiomyocytes with a contractile frequency of about 1 Hz. We also employed the β-adrenergic agonist isoproterenol (100 nmol l-1) and observed that our cantilever demonstrated high sensitivity in detecting subtle changes in both chronotropic and inotropic responses of monolayers. This report describes the utility of our micro-device in both basic cardiovascular research as well as in small molecule drug discovery to monitor cardiac cell contractions.

  3. Spontaneous Ca2+ release from the sarcoplasmic reticulum limits Ca2+- dependent twitch potentiation in individual cardiac myocytes. A mechanism for maximum inotropy in the myocardium

    OpenAIRE

    1988-01-01

    We hypothesized that the occurrence of spontaneous Ca2+ release from the sarcoplasmic reticulum (SR), in diastole, might be a mechanism for the saturation of twitch potentiation common to a variety of inotropic perturbations that increase the total cell Ca. We used a videomicroscopic technique in single cardiac myocytes to quantify the amplitude of electrically stimulated twitches and to monitor the occurrence of the mechanical manifestation of spontaneous SR Ca2+ release, i.e., the spontaneo...

  4. Variations in Local Calcium Signaling in Adjacent Cardiac Myocytes of the Intact Mouse Heart Detected with Two-Dimensional Confocal Microscopy

    Directory of Open Access Journals (Sweden)

    Karin P Hammer

    2015-01-01

    Full Text Available Dyssynchronous local Ca release within individual cardiac myocytes has been linked to cellular contractile dysfunction. Differences in Ca kinetics in adjacent cells may also provide a substrate for inefficient contraction and arrhythmias. In a new approach we quantify variation in local Ca transients between adjacent myocytes in the whole heart.Langendorff-perfused mouse hearts were loaded with Fluo-8 AM to detect Ca and Di-4-ANEPPS to visualize cell membranes. A spinning disc confocal microscope with a fast camera allowed us to record Ca signals within an area of 465 µm by 315 µm with an acquisition speed of 55 fps. Images from multiple transients recorded at steady state were registered to their time point in the cardiac cycle to restore averaged local Ca transients with a higher temporal resolution. Local Ca transients within and between adjacent myocytes were compared with regard to amplitude, time to peak and decay at steady state stimulation (250 ms cycle length.Image registration from multiple sequential Ca transients allowed reconstruction of high temporal resolution (2.4 ±1.3ms local CaT in 2D image sets (N= 4 hearts, n= 8 regions. During steady state stimulation, spatial Ca gradients were homogeneous within cells in both directions and independent of distance between measured points. Variation in CaT amplitudes was similar across the short and the long side of neighboring cells. Variations in TAU and TTP were similar in both directions. Isoproterenol enhanced the CaT but not the overall pattern of spatial heterogeneities.Here we detected and analyzed local Ca signals in intact mouse hearts with high temporal and spatial resolution, taking into account 2D arrangement of the cells. We observed significant differences in the variation of CaT amplitude along the long and short axis of cardiac myocytes. Variations of Ca signals between neighboring cells may contribute to the substrate of cardiac remodeling.

  5. Regional electroporation of single cardiac myocytes in a focused electric field.

    Science.gov (United States)

    Klauke, Norbert; Smith, Godfrey; Cooper, Jonathan M

    2010-01-15

    There is now a significant interest in being able to locate single cells within geometrically defined regions of a microfluidic chip and to gain intracellular access through the local electroporation of the cell membrane. This paper describes the microfabrication of electroporation devices which can enable the regional electroporation of adult ventricular myocytes, in order to lower the local electrical resistance of the cell membrane. Initially three different devices, designed to suit the characteristic geometry of the cardiomyocyte, were investigated (all three designs serve to focus the electric field to selected regions of the cell). We demonstrate that one of these three devices revealed the sequence of cellular responses to field strengths of increasing magnitudes, namely, cell contraction, hypercontraction, and lysis. This same device required a reduced threshold voltage for each of these events, including in particular membrane breakdown. We were not only able to show the gradual regional increase in the electric conductivity of the cell membrane but were also able to avoid changes in the local intra- and extracellular pH (by preventing the local generation of protons at the electrode surface, as a consequence of the reduced threshold voltage). The paper provides evidence for new strategies for achieving robust and reproducible regional electroporation, a technique which, in future, may be used for the insertion of large molecular weight molecules (including genes) as well as for on-chip voltage clamping of the primary adult cardiomyocyte.

  6. Modulation of the transient outward current (Ito) in rat cardiac myocytes and human Kv4.3 channels by mefloquine.

    Science.gov (United States)

    Perez-Cortes, E J; Islas, A A; Arevalo, J P; Mancilla, C; Monjaraz, E; Salinas-Stefanon, E M

    2015-10-15

    The antimalarial drug mefloquine, is known to be a potassium channel blocker, although its mechanism of action has not being elucidated and its effects on the transient outward current (Ito) and the molecular correlate, the Kv4.3 channel has not being studied. Here, we describe the mefloquine-induced inhibition of the rat ventricular Ito and of CHO cells co-transfected with human Kv4.3 and its accessory subunit hKChIP2C by whole-cell voltage-clamp. Mefloquine inhibited rat Ito and hKv4.3+KChIP2C currents in a concentration-dependent manner with a limited voltage dependence and similar potencies (IC50=8.9μM and 10.5μM for cardiac myocytes and Kv4.3 channels, respectively). In addition, mefloquine did not affect the activation of either current but significantly modified the hKv4.3 steady-state inactivation and recovery from inactivation. The effects of this drug was compared with that of 4-aminopyridine (4-AP), a well-known potassium channel blocker and its binding site does not seem to overlap with that of 4-AP.

  7. Angiotensin II Type 1 Receptor-Mediated Electrical Remodeling in Mouse Cardiac Myocytes.

    Directory of Open Access Journals (Sweden)

    Jeremy Kim

    Full Text Available We recently characterized an autocrine renin angiotensin system (RAS in canine heart. Activation of Angiotensin II Type 1 Receptors (AT1Rs induced electrical remodeling, including inhibition of the transient outward potassium current Ito, prolongation of the action potential (AP, increased calcium entry and increased contractility. Electrical properties of the mouse heart are very different from those of dog heart, but if a similar system existed in mouse, it could be uniquely studied through genetic manipulations. To investigate the presence of a RAS in mouse, we measured APs and Ito in isolated myocytes. Application of angiotensin II (A2 for 2 or more hours reduced Ito magnitude, without affecting voltage dependence, and prolonged APs in a dose-dependent manner. Based on dose-inhibition curves, the fast and slow components of Ito (Ito,fast and IK,slow appeared to be coherently regulated by [A2], with 50% inhibition at an A2 concentration of about 400 nM. This very high K0.5 is inconsistent with systemic A2 effects, but is consistent with an autocrine RAS in mouse heart. Pre-application of the microtubule destabilizing agent colchicine eliminated A2 effects on Ito and AP duration, suggesting these effects depend on intracellular trafficking. Application of the biased agonist SII ([Sar1-Ile4-Ile8]A2, which stimulates receptor internalization without G protein activation, caused Ito reduction and AP prolongation similar to A2-induced changes. These data demonstrate AT1R mediated regulation of Ito in mouse heart. Moreover, all measured properties parallel those measured in dog heart, suggesting an autocrine RAS may be a fundamental feedback system that is present across species.

  8. Sequential dissection of multiple ionic currents in single cardiac myocytes under action potential-clamp.

    Science.gov (United States)

    Banyasz, Tamas; Horvath, Balazs; Jian, Zhong; Izu, Leighton T; Chen-Izu, Ye

    2011-03-01

    The cardiac action potential (AP) is shaped by myriad ionic currents. In this study, we develop an innovative AP-clamp Sequential Dissection technique to enable the recording of multiple ionic currents in the single cell under AP-clamp. This new technique presents a significant step beyond the traditional way of recording only one current in any one cell. The ability to measure many currents in a single cell has revealed two hitherto unknown characteristics of the ionic currents in cardiac cells: coordination of currents within a cell and large variation of currents between cells. Hence, the AP-clamp Sequential Dissection method provides a unique and powerful tool for studying individual cell electrophysiology.

  9. Modulation of cardiac myocyte phenotype in vitro by the composition and orientation of the extracellular matrix.

    Science.gov (United States)

    Simpson, D G; Terracio, L; Terracio, M; Price, R L; Turner, D C; Borg, T K

    1994-10-01

    Cellular phenotype is the result of a dynamic interaction between a cell's intrinsic genetic program and the morphogenetic signals that serve to modulate the extent to which that program is expressed. In the present study we have examined how morphogenetic information might be stored in the extracellular matrix (ECM) and communicated to the neonatal heart cell (NHC) by the cardiac alpha 1 beta 1 integrin molecule. A thin film of type I collagen (T1C) was prepared with a defined orientation. This was achieved by applying T1C to the peripheral edge of a 100 mm culture dish. The T1C was then drawn across the surface of the dish in a continuous stroke with a sterile cell scraper and allowed to polymerize. When NHCs were cultured on this substrate, they spread, as a population, along a common axis in parallel with the gel lattice and expressed an in vivo-like phenotype. Individual NHCs displayed an elongated, rod-like shape and disclosed parallel arrays of myofibrils. These phenotypic characteristics were maintained for at least 4 weeks in primary culture. The evolution of this tissue-like organizational pattern was dependent upon specific interactions between the NHCs and the collagen-based matrix that were mediated by the cardiac alpha 1 beta 1 integrin complex. This conclusion was supported by a variety of experimental results. Altering the tertiary structure of the matrix or blocking the extracellular domains of either the cardiac alpha 1 or beta 1 integrin chain inhibited the expression of the tissue-like pattern of organization. Neither cell-to-cell contact or contractile function were necessary to induce the formation of the rod-like cell shape. However, beating activity was necessary for the assembly of a well-differentiated myofibrillar apparatus. These data suggest that the cardiac alpha 1 beta 1 integrin complex serves to detect and transduce phenotypic information stored within the tertiary structure of the surrounding matrix.

  10. Diabetic cardiomyopathy: from the pathophysiology of the cardiac myocytes to current diagnosis and management strategies

    Directory of Open Access Journals (Sweden)

    Christina Voulgari

    2010-10-01

    Full Text Available Christina Voulgari, Dimitrios Papadogiannis, Nicholas TentolourisFirst Department of Propaedeutic and Internal Medicine, Athens University Medical School, Laiko General Hospital, Athens, GreeceAbstract: Diabetic cardiomyopathy (DCM, although a distinct clinical entity, is also a part of the diabetic atherosclerosis process. It may be independent of the coexistence of ischemic heart disease, hypertension, or other macrovascular complications. Its pathological substrate is characterized by the presence of myocardial damage, reactive hypertrophy, and intermediary fibrosis, structural and functional changes of the small coronary vessels, disturbance of the management of the metabolic cardiovascular load, and cardiac autonomic neuropathy. These alterations make the diabetic heart susceptible to ischemia and less able to recover from an ischemic attack. Arterial hypertension frequently coexists with and exacerbates cardiac functioning, leading to the premature appearance of heart failure. Classical and newer echocardiographic methods are available for early diagnosis. Currently, there is no specific treatment for DCM; targeting its pathophysiological substrate by effective risk management protects the myocardium from further damage and has a recognized primary role in its prevention. Its pathophysiological substrate is also the objective for the new therapies and alternative remedies.Keywords: cardiovascular disease, atherosclerosis, cardiac autonomic neuropathy, echocardiography, treatment strategies

  11. Differential extracellular signal-regulated kinases 1 and 2 activation by the angiotensin type 1 receptor supports distinct phenotypes of cardiac myocytes

    DEFF Research Database (Denmark)

    Aplin, Mark; Christensen, Gitte Lund; Schneider, Mikael;

    2007-01-01

    The angiotensin II (AngII) type 1 receptor (AT(1)R) is a seven-transmembrane receptor well established to activate extracellular signal-regulated kinases 1 and 2 (ERK1/2) by discrete G protein-dependent and beta-arrestin2-dependent pathways. The biological importance of this, however, remains...... that phosphorylates p90 Ribosomal S6 Kinase, a ubiquitous and versatile mediator of ERK1/2 signal transduction. Moreover, the beta-arrestin2-dependent ERK1/2 signal supports intact proliferation of cardiac myocytes. In contrast to G(q)-activated ERK1/2, and in keeping with its failure to translocate to the nucleus......, the beta-arrestin2-scaffolded pool of ERK1/2 does not phosphorylate the transcription factor Elk-1, induces no increased transcription of the immediate-early gene c-Fos, and does not entail myocyte hypertrophy. These results clearly demonstrate the biological significance of differential signalling...

  12. Morphological Modifications in Myofibrils by Suppressing Tropomyosin 4α in Chicken Cardiac Myocytes.

    Science.gov (United States)

    Toyota, Naoji; Fujitsuka, Chiaki; Ishibashi, Goushi; S Yoshida, Lucia; Takano-Ohmuro, Hiromi

    2016-01-01

    Tropomyosin (TPM) localizes along F-actin and, together with troponin T (TnT) and other components, controls calcium-sensitive muscle contraction. The role of the TPM isoform (TPM4α) that is expressed in embryonic and adult cardiac muscle cells in chicken is poorly understood. To analyze the function of TPM4α in myofibrils, the effects of TPM4α-suppression were examined in embryonic cardiomyocytes by small interference RNA transfection. Localization of myofibril proteins such as TPM, actin, TnT, α-actinin, myosin and connectin was examined by immunofluorescence microscopy on day 5 when almost complete TPM4α-suppression occurred in culture. A unique large structure was detected, consisting of an actin aggregate bulging from the actin bundle, and many curved filaments projecting from the aggregate. TPM, TnT and actin were detected on the large structure, but myosin, connectin, α-actinin and obvious myofibril striations were undetectable. It is possible that TPM4α-suppressed actin filaments are sorted and excluded at the place of the large structure. This suggests that TPM4α-suppression significantly affects actin filament, and that TPM4α plays an important role in constructing and maintaining sarcomeres and myofibrils in cardiac muscle.

  13. [Structural and metabolic aspects of heterogenicity of the ventricular cardiac myocytes in coronary insufficiency].

    Science.gov (United States)

    Gavrish, A S; Blagodarov, V N; Verbitskiĭ, V V; Danilishina, M V

    2003-01-01

    The paper shows comparative analysis of structural-metabolic changes of the ventricular cardiac hystiocytes during transitional restriction of blood supply, which leads to relapsing myocardium hypoperfusion, ischemia and even to cardiac infarction. We have established that an increase of the myocardium arrhythmogenicity, damage of myocardium electrophysiological activity and coronary deficiency are caused by pathologically intensified structural-metabolic heterogeneity of cardiomyocites. The chronic ischemic heart disease is worsening the situation by gradual accumulation of the metastructure changes of heart's working cells. It is possible to connect adaptable hypertrophy of cardiomyocites with compensatory redistribution of loading among them, what is accompanied with the deep reorganization of their metabolism and metastructure under the influence of neurohumoral factors, inadequate transport-trophic maintenance of the function, nonequal edema and fibrosis of the interstitium. The data obtained describe the formation of "prereadiness" of the myocardium to the fatal rhythm disturbance determined by interconnected structural-metabolic changes. Each of these pathological changes separately doesn't induce an impairment of myocardium electric stability but represents a necessary part in origin and development of the pathological process.

  14. Tissue-Mimicking Geometrical Constraints Stimulate Tissue-Like Constitution and Activity of Mouse Neonatal and Human-Induced Pluripotent Stem Cell-Derived Cardiac Myocytes

    Directory of Open Access Journals (Sweden)

    Götz Pilarczyk

    2016-01-01

    Full Text Available The present work addresses the question of to what extent a geometrical support acts as a physiological determining template in the setup of artificial cardiac tissue. Surface patterns with alternating concave to convex transitions of cell size dimensions were used to organize and orientate human-induced pluripotent stem cell (hIPSC-derived cardiac myocytes and mouse neonatal cardiac myocytes. The shape of the cells, as well as the organization of the contractile apparatus recapitulates the anisotropic line pattern geometry being derived from tissue geometry motives. The intracellular organization of the contractile apparatus and the cell coupling via gap junctions of cell assemblies growing in a random or organized pattern were examined. Cell spatial and temporal coordinated excitation and contraction has been compared on plain and patterned substrates. While the α-actinin cytoskeletal organization is comparable to terminally-developed native ventricular tissue, connexin-43 expression does not recapitulate gap junction distribution of heart muscle tissue. However, coordinated contractions could be observed. The results of tissue-like cell ensemble organization open new insights into geometry-dependent cell organization, the cultivation of artificial heart tissue from stem cells and the anisotropy-dependent activity of therapeutic compounds.

  15. Early Regulation of Profibrotic Genes in Primary Human Cardiac Myocytes by Trypanosoma cruzi.

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    Aniekanabassi N Udoko

    2016-01-01

    Full Text Available The molecular mechanisms of Trypanosoma cruzi induced cardiac fibrosis remains to be elucidated. Primary human cardiomyoctes (PHCM exposed to invasive T. cruzi trypomastigotes were used for transcriptome profiling and downstream bioinformatic analysis to determine fibrotic-associated genes regulated early during infection process (0 to 120 minutes. The identification of early molecular host responses to T. cruzi infection can be exploited to delineate important molecular signatures that can be used for the classification of Chagasic patients at risk of developing heart disease. Our results show distinct gene network architecture with multiple gene networks modulated by the parasite with an incline towards progression to a fibrogenic phenotype. Early during infection, T. cruzi significantly upregulated transcription factors including activator protein 1 (AP1 transcription factor network components (including FOSB, FOS and JUNB, early growth response proteins 1 and 3 (EGR1, EGR3, and cytokines/chemokines (IL5, IL6, IL13, CCL11, which have all been implicated in the onset of fibrosis. The changes in our selected genes of interest did not all start at the same time point. The transcriptome microarray data, validated by quantitative Real-Time PCR, was also confirmed by immunoblotting and customized Enzyme Linked Immunosorbent Assays (ELISA array showing significant increases in the protein expression levels of fibrogenic EGR1, SNAI1 and IL 6. Furthermore, phosphorylated SMAD2/3 which induces a fibrogenic phenotype is also upregulated accompanied by an increased nuclear translocation of JunB. Pathway analysis of the validated genes and phospho-proteins regulated by the parasite provides the very early fibrotic interactome operating when T. cruzi comes in contact with PHCM. The interactome architecture shows that the parasite induces both TGF-β dependent and independent fibrotic pathways, providing an early molecular foundation for Chagasic

  16. The Scaffold Protein Muscle A-Kinase Anchoring Protein β Orchestrates Cardiac Myocyte Hypertrophic Signaling Required for the Development of Heart Failure

    Science.gov (United States)

    Kritzer, Michael D.; Li, Jinliang; Passariello, Catherine L.; Gayanilo, Marjorie; Thakur, Hrishikesh; Dayan, Joseph; Dodge-Kafka, Kimberly; Kapiloff, Michael S.

    2014-01-01

    Background Cardiac myocyte hypertrophy is regulated by an extensive intracellular signal transduction network. In vitro evidence suggests that the scaffold protein muscle A-kinase anchoring protein β (mAKAPβ) serves as a nodal organizer of hypertrophic signaling. However, the relevance of mAKAPβ signalosomes to pathological remodeling and heart failure in vivo remains unknown. Methods and Results Using conditional, cardiac myocyte–specific gene deletion, we now demonstrate that mAKAPβ expression in mice is important for the cardiac hypertrophy induced by pressure overload and catecholamine toxicity. mAKAPβ targeting prevented the development of heart failure associated with long-term transverse aortic constriction, conferring a survival benefit. In contrast to 29% of control mice (n=24), only 6% of mAKAPβ knockout mice (n=31) died in the 16 weeks of pressure overload (P=0.02). Accordingly, mAKAPβ knockout inhibited myocardial apoptosis and the development of interstitial fibrosis, left atrial hypertrophy, and pulmonary edema. This improvement in cardiac status correlated with the attenuated activation of signaling pathways coordinated by the mAKAPβ scaffold, including the decreased phosphorylation of protein kinase D1 and histone deacetylase 4 that we reveal to participate in a new mAKAP signaling module. Furthermore, mAKAPβ knockout inhibited pathological gene expression directed by myocyte-enhancer factor-2 and nuclear factor of activated T-cell transcription factors that associate with the scaffold. Conclusions mAKAPβ orchestrates signaling that regulates pathological cardiac remodeling in mice. Targeting of the underlying physical architecture of signaling networks, including mAKAPβ signalosome formation, may constitute an effective therapeutic strategy for the prevention and treatment of pathological remodeling and heart failure. PMID:24812305

  17. Activation of extracellular signal-regulated kinase during silibinin-protected, isoproterenol-induced apoptosis in rat cardiac myocytes is tyrosine kinase pathway-mediated and protein kinase C-dependent

    Institute of Scientific and Technical Information of China (English)

    Bei ZHOU; Li-jun WU; Shin-ichi TASHIRO; Satoshi ONODERA; Fumiaki UCHIUMI; Takashi IKEJIMA

    2007-01-01

    Aim: To investigate the mechanism of silibinin-protected isoproterenol-induced apoptosis in rat cardiac myocytes.Methods: The viability of rat cardiac myocytes was measured by MTT method. The apoptotic ratio was measured by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling. Protein kinase C (PKC) activity assay was carried out according to the instructions of the PepTag non-radioactive protein kinase C assay kit. Western blot analysis was used to evaluate the level of Ras, Raf-1 and mitogen-activated protein kinase (MAPK) expression.Results: The protective effects of silibinin were significantly sup-pressed by inhibitors, including genistein, manumycin A and GW5074 [inhibitors for protein tyrosine kinases (PTK), Ras and Raf- 1, respectively]. The exposure of rat cardiac myocytes to isoproterenol alone caused decreased PKC activity, which was prevented by pretreatment with silibinin dose-dependently. Simultaneously,the increased expression of Ras and Raf-1 activated by silibinin were blocked by the PKC inhibitor, stauroporine. In addition, the extracellularly responsive kinase (ERK) inhibitor, PD98059, suppressed silibinin-protected apoptosis, whereas the p38 MAPK inhibitor, SB203580, protected cardiac myocytes from isoproterenol-induced injury, and the c-Jun N-terminal kinase (JNK) inhibitor, SP600125 had no protective effects. Furthermore, Western blot analysis showed that the expres-sion of phosphorylated ERK was increased by silibinin, the expression of phos-phorylated p38 MAPK was decreased and total ERK, p38, JNK and phosphory-lated JNK MAPK did not change after treatment with both isoproterenol and silibinin. Furthermore, pretreatment of cardiac myocyte with PKC, Ras and Raf inhibitors significantly blocked ERK phosphorylation.Conclusion: Silibinin is suggested to protect isoproterenol-induced rat cardiac myocyte apoptosis by activating the tyrosine kinase pathway, PKC and MAPK pathways.

  18. Pre-Conditioning with CDP-Choline Attenuates Oxidative Stress-Induced Cardiac Myocyte Death in a Hypoxia/Reperfusion Model

    Science.gov (United States)

    González-Pacheco, Héctor; Méndez-Domínguez, Aurelio; Hernández, Salomón; López-Marure, Rebeca; Vazquez-Mellado, Maria J.; Aguilar, Cecilia; Rocha-Zavaleta, Leticia

    2014-01-01

    Background. CDP-choline is a key intermediate in the biosynthesis of phosphatidylcholine, which is an essential component of cellular membranes, and a cell signalling mediator. CDP-choline has been used for the treatment of cerebral ischaemia, showing beneficial effects. However, its potential benefit for the treatment of myocardial ischaemia has not been explored yet. Aim. In the present work, we aimed to evaluate the potential use of CDP-choline as a cardioprotector in an in vitro model of ischaemia/reperfusion injury. Methods. Neonatal rat cardiac myocytes were isolated and subjected to hypoxia/reperfusion using the coverslip hypoxia model. To evaluate the effect of CDP-choline on oxidative stress-induced reperfusion injury, the cells were incubated with H2O2 during reperfusion. The effect of CDP-choline pre- and postconditioning was evaluated using the cell viability MTT assay, and the proportion of apoptotic and necrotic cells was analyzed using the Annexin V determination by flow cytometry. Results. Pre- and postconditioning with 50 mg/mL of CDP-choline induced a significant reduction of cells undergoing apoptosis after hypoxia/reperfusion. Preconditioning with CDP-choline attenuated postreperfusion cell death induced by oxidative stress. Conclusion. CDP-choline administration reduces cell apoptosis induced by oxidative stress after hypoxia/reperfusion of cardiac myocytes. Thus, it has a potential as cardioprotector in ischaemia/reperfusion-injured cardiomyocytes. PMID:24578622

  19. Contribution of spontaneous L-type Ca2+ channel activation to the genesis of Ca2+ sparks in resting cardiac myocytes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guangqin; FU Yu; YANG Dongmei; HAO Xuemei; BAI Shuhua; TANG Yiqun; Edward G LAKATTA; WU Caihong; CHENG Heping

    2004-01-01

    Ca2+ sparks are the elementary events of intracellular Ca2+ release from the sarcoplasmic reticulum in cardiac myocytes. In order to investigate whether spontaneous L-type Ca2+ channel activation contributes to the genesis of spontaneous Ca2+ sparks, we used confocal laser scanning microscopy and fluo-4 to visualize local Ca2+ sparks in intact rat ventricular myocytes. In the presence of 0.2 mmol/L CdCl2 which inhibits spontaneous L-type Ca2+ channel activation, the rate of occurrence of spontaneous Ca2+ sparks was halved from 4.20 to 2.04 events/(100 μm·s), with temporal and spatial properties of individual Ca2+ sparks unchanged. Analysis of the Cd2+-sensitive spark production revealed an open probability of ~10-5 for L-type channels at the rest membrane potentials (-80 mV). Thus, infrequent and stochastic openings of sarcolemmal L-type Ca2+ channels in resting heart cells contribute significantly to the production of spontaneous Ca2+ sparks.

  20. Steady-state solutions of cell volume in a cardiac myocyte model elaborated for membrane excitation, ion homeostasis and Ca2+ dynamics.

    Science.gov (United States)

    Cha, Chae Young; Noma, Akinori

    2012-08-21

    The cell volume continuously changes in response to varying physiological conditions, and mechanisms underlying volume regulation have been investigated in both experimental and theoretical studies. Here, general formulations concerning cell volume change are presented in the context of developing a comprehensive cell model which takes Ca(2+) dynamics into account. Explicit formulas for charge conservation and steady-state volumes of the cytosol and endoplasmic reticulum (ER) are derived in terms of membrane potential, amount of ions, Ca(2+)-bound buffer molecules, and initial cellular conditions. The formulations were applied to a ventricular myocyte model which has plasma-membrane Ca(2+) currents with dynamic gating mechanisms, Ca(2+)-buffering reactions with diffusive and non-diffusive buffer proteins, and Ca(2+) uptake into or release from the sarcoplasmic reticulum (SR) accompanied by compensatory cationic or anionic currents through the SR membrane. Time-dependent volume changes in cardiac myocytes induced by varying extracellular osmolarity or by action potential generation were successfully simulated by the novel formulations. Through application of bifurcation analysis, the existence and uniqueness of steady-state solutions of the cell volume were validated, and contributions of individual ion channels and transporters to the steady-state volume were systematically analyzed. The new formulas are consistent with previous fundamental theory derived from simple models of minimum compositions. The new formulations may be useful for examination of the relationship between cell function and volume change in other cell types.

  1. Chloride current in mammalian cardiac myocytes. Novel mechanism for autonomic regulation of action potential duration and resting membrane potential

    OpenAIRE

    1990-01-01

    The properties of the autonomically regulated chloride current (ICl) were studied in isolated guinea pig ventricular myocytes. This current was elicited upon exposure to isoproterenol (ISO) and reversed upon concurrent exposure to acetylcholine (ACh). ICl was time independent and exhibited outward rectification. The responses to ISO and ACh could be blocked by propranolol and atropine, respectively, and ICl was also elicited by forskolin, 8-bromoadenosine 3',5'-cyclic monophosphate, and 3-iso...

  2. Exercise training and detraining modify the morphological and mechanical properties of single cardiac myocytes obtained from spontaneously hypertensive rats.

    Science.gov (United States)

    Carneiro-Júnior, M A; Pelúzio, M C G; Silva, C H O; Amorim, P R S; Silva, K A; Souza, M O; Castro, C A; Roman-Campos, D; Prímola-Gomes, T N; Natali, A J

    2010-11-01

    We determined the effects of exercise training and detraining on the morphological and mechanical properties of left ventricular myocytes in 4-month-old spontaneously hypertensive rats (SHR) randomly divided into the following groups: sedentary for 8 weeks (SED-8), sedentary for 12 weeks (SED-12), treadmill-running trained for 8 weeks (TRA, 16 m/min, 60 min/day, 5 days/week), and treadmill-running trained for 8 weeks followed by 4 weeks of detraining (DET). At sacrifice, left ventricular myocytes were isolated enzymatically, and resting cell length, width, and cell shortening after stimulation at a frequency of 1 Hz (~25°C) were measured. Cell length was greater in TRA than in SED-8 (161.30 ± 1.01 vs 156.10 ± 1.02 μm, P exercise training or detraining. Cell length to width ratio was higher in TRA than in SED-8 (8.50 ± 0.08 vs 8.22 ± 0.10, P Exercise training did not affect cell shortening, which was unchanged with detraining. TRA cells exhibited higher maximum velocity of shortening than SED-8 (102.01 ± 4.50 vs 82.01 ± 5.30 μm/s, P exercise training affected left ventricle remodeling in SHR towards eccentric hypertrophy, which remained after detraining. It also improved single left ventricular myocyte contractile function, which was reversed by detraining.

  3. Nitric oxide-dependent activation of CaMKII increases diastolic sarcoplasmic reticulum calcium release in cardiac myocytes in response to adrenergic stimulation.

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    Jerry Curran

    Full Text Available Spontaneous calcium waves in cardiac myocytes are caused by diastolic sarcoplasmic reticulum release (SR Ca(2+ leak through ryanodine receptors. Beta-adrenergic (β-AR tone is known to increase this leak through the activation of Ca-calmodulin-dependent protein kinase (CaMKII and the subsequent phosphorylation of the ryanodine receptor. When β-AR drive is chronic, as observed in heart failure, this CaMKII-dependent effect is exaggerated and becomes potentially arrhythmogenic. Recent evidence has indicated that CaMKII activation can be regulated by cellular oxidizing agents, such as reactive oxygen species. Here, we investigate how the cellular second messenger, nitric oxide, mediates CaMKII activity downstream of the adrenergic signaling cascade and promotes the generation of arrhythmogenic spontaneous Ca(2+ waves in intact cardiomyocytes. Both SCaWs and SR Ca(2+ leak were measured in intact rabbit and mouse ventricular myocytes loaded with the Ca-dependent fluorescent dye, fluo-4. CaMKII activity in vitro and immunoblotting for phosphorylated residues on CaMKII, nitric oxide synthase, and Akt were measured to confirm activity of these enzymes as part of the adrenergic cascade. We demonstrate that stimulation of the β-AR pathway by isoproterenol increased the CaMKII-dependent SR Ca(2+ leak. This increased leak was prevented by inhibition of nitric oxide synthase 1 but not nitric oxide synthase 3. In ventricular myocytes isolated from wild-type mice, isoproterenol stimulation also increased the CaMKII-dependent leak. Critically, in myocytes isolated from nitric oxide synthase 1 knock-out mice this effect is ablated. We show that isoproterenol stimulation leads to an increase in nitric oxide production, and nitric oxide alone is sufficient to activate CaMKII and increase SR Ca(2+ leak. Mechanistically, our data links Akt to nitric oxide synthase 1 activation downstream of β-AR stimulation. Collectively, this evidence supports the hypothesis

  4. Effects of adding intravenous nicorandil to standard therapy on cardiac sympathetic nerve activity and myocyte dysfunction in patients with acute decompensated heart failure

    Energy Technology Data Exchange (ETDEWEB)

    Kasama, Shu [Gunma University Graduate School of Medicine, Department of Medicine and Biological Science (Cardiovascular Medicine), Maebashi, Gunma (Japan); Cardiovascular Hospital of Central Japan (Kitakanto Cardiovascular Hospital), Department of Cardiovascular Medicine, Gunma (Japan); Toyama, Takuji; Funada, Ryuichi; Takama, Noriaki; Koitabashi, Norimichi; Kurabayashi, Masahiko [Gunma University Graduate School of Medicine, Department of Medicine and Biological Science (Cardiovascular Medicine), Maebashi, Gunma (Japan); Ichikawa, Shuichi [Cardiovascular Hospital of Central Japan (Kitakanto Cardiovascular Hospital), Department of Cardiovascular Medicine, Gunma (Japan); Suzuki, Yasuyuki; Matsumoto, Naoya [Nihon University School of Medicine, Department of Cardiology, Tokyo (Japan); Sato, Yuichi [Health Park Clinic, Department of Imaging, Takasaki, Gunma (Japan)

    2015-04-01

    Nicorandil, an adenosine triphosphate-sensitive potassium channel opener, improves cardiac sympathetic nerve activity (CSNA) in ischemic heart disease or chronic heart failure. However, its effects on CSNA and myocyte dysfunction in acute heart failure (AHF) remain unclear. We investigated the effects of adding intravenous nicorandil to standard therapy on CSNA and myocyte dysfunction in AHF. We selected 70 patients with mild to moderate nonischemic AHF who were treated with standard conventional therapy soon after admission. Thirty-five patients were assigned to additionally receive intravenous nicorandil (4-12 mg/h; group A), whereas the remaining patients continued their current drug regimen (group B). Delayed total defect score (TDS), delayed heart to mediastinum count (H/M) ratio, and washout rate (WR) were determined by {sup 123}I-metaiodobenzylguanidine (MIBG) scintigraphy within 3 days of admission and 4 weeks later. High sensitivity troponin T (hs-TnT) level was also measured at the same time points. After treatment, MIBG scintigraphic parameters significantly improved in both groups. However, the extent of the changes in these parameters in group A significantly exceeded the extent of the changes in group B [TDS -11.3 ± 4.3 in group A vs -4.0 ± 6.0 in group B (p < 0.01); H/M ratio 0.31 ± 0.16 vs 0.14 ± 0.16 (p < 0.01); WR -13.8 ± 7.8 % vs -6.1 ± 8.9 % (p < 0.01)]. The hs-TnT level decreased significantly from 0.052 ± 0.043 to 0.041 ± 0.033 ng/ml (p < 0.05) in group A, but showed no significant change in group B. Moreover, in both groups, no relationships between the extent of changes in MIBG parameters and hs-TnT level were observed. Adding intravenous nicorandil to standard therapy provides additional benefits for CSNA and myocyte dysfunction over conventional therapy alone in AHF patients. Furthermore, the mechanisms of improvement in CSNA and myocyte dysfunction after nicorandil treatment in AHF patients were distinct. (orig.)

  5. Stearoyl-CoA desaturase-1 (SCD1 augments saturated fatty acid-induced lipid accumulation and inhibits apoptosis in cardiac myocytes.

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    Hiroki Matsui

    Full Text Available Mismatch between the uptake and utilization of long-chain fatty acids in the myocardium leads to abnormally high intracellular fatty acid concentration, which ultimately induces myocardial dysfunction. Stearoyl-Coenzyme A desaturase-1 (SCD1 is a rate-limiting enzyme that converts saturated fatty acids (SFAs to monounsaturated fatty acids. Previous studies have shown that SCD1-deficinent mice are protected from insulin resistance and diet-induced obesity; however, the role of SCD1 in the heart remains to be determined. We examined the expression of SCD1 in obese rat hearts induced by a sucrose-rich diet for 3 months. We also examined the effect of SCD1 on myocardial energy metabolism and apoptotic cell death in neonatal rat cardiac myocytes in the presence of SFAs. Here we showed that the expression of SCD1 increases 3.6-fold without measurable change in the expression of lipogenic genes in the heart of rats fed a high-sucrose diet. Forced SCD1 expression augmented palmitic acid-induced lipid accumulation, but attenuated excess fatty acid oxidation and restored reduced glucose oxidation. Of importance, SCD1 substantially inhibited SFA-induced caspase 3 activation, ceramide synthesis, diacylglycerol synthesis, apoptotic cell death, and mitochondrial reactive oxygen species (ROS generation. Experiments using SCD1 siRNA confirmed these observations. Furthermore, we showed that exposure of cardiac myocytes to glucose and insulin induced SCD1 expression. Our results indicate that SCD1 is highly regulated by a metabolic syndrome component in the heart, and such induction of SCD1 serves to alleviate SFA-induced adverse fatty acid catabolism, and eventually to prevent SFAs-induced apoptosis.

  6. Shortening and intracellular Ca2+ in ventricular myocytes and expression of genes encoding cardiac muscle proteins in early onset type 2 diabetic Goto-Kakizaki rats.

    Science.gov (United States)

    Salem, K A; Adrian, T E; Qureshi, M A; Parekh, K; Oz, M; Howarth, F C

    2012-12-01

    There has been a spectacular rise in the global prevalence of type 2 diabetes mellitus. Cardiovascular complications are the major cause of morbidity and mortality in diabetic patients. Contractile dysfunction, associated with disturbances in excitation-contraction coupling, has been widely demonstrated in the diabetic heart. The aim of this study was to investigate the pattern of cardiac muscle genes that are involved in the process of excitation-contraction coupling in the hearts of early onset (8-10 weeks of age) type 2 diabetic Goto-Kakizaki (GK) rats. Gene expression was assessed in ventricular muscle with real-time RT-PCR; shortening and intracellular Ca(2+) were measured in ventricular myocytes with video edge detection and fluorescence photometry, respectively. The general characteristics of the GK rats included elevated fasting and non-fasting blood glucose and blood glucose at 120 min following a glucose challenge. Expression of genes encoding cardiac muscle proteins (Myh6/7, Mybpc3, Myl1/3, Actc1, Tnni3, Tnn2, Tpm1/2/4 and Dbi) and intercellular proteins (Gja1/4/5/7, Dsp and Cav1/3) were unaltered in GK ventricle compared with control ventricle. The expression of genes encoding some membrane pumps and exchange proteins was unaltered (Atp1a1/2, Atp1b1 and Slc8a1), whilst others were either upregulated (Atp1a3, relative expression 2.61 ± 0.69 versus 0.84 ± 0.23) or downregulated (Slc9a1, 0.62 ± 0.07 versus 1.08 ± 0.08) in GK ventricle compared with control ventricle. The expression of genes encoding some calcium (Cacna1c/1g, Cacna2d1/2d2 and Cacnb1/b2), sodium (Scn5a) and potassium channels (Kcna3/5, Kcnj3/5/8/11/12, Kchip2, Kcnab1, Kcnb1, Kcnd1/2/3, Kcne1/4, Kcnq1, Kcng2, Kcnh2, Kcnk3 and Kcnn2) were unaltered, whilst others were either upregulated (Cacna1h, 0.95 ± 0.16 versus 0.47 ± 0.09; Scn1b, 1.84 ± 0.16 versus 1.11 ± 0.11; and Hcn2, 1.55 ± 0.15 versus 1.03 ± 0.08) or downregulated (Hcn4, 0.16 ± 0.03 versus 0.37 ± 0.08; Kcna2, 0.35 ± 0

  7. Exercise training and detraining modify the morphological and mechanical properties of single cardiac myocytes obtained from spontaneously hypertensive rats

    Directory of Open Access Journals (Sweden)

    M.A. Carneiro-Júnior

    2010-11-01

    Full Text Available We determined the effects of exercise training and detraining on the morphological and mechanical properties of left ventricular myocytes in 4-month-old spontaneously hypertensive rats (SHR randomly divided into the following groups: sedentary for 8 weeks (SED-8, sedentary for 12 weeks (SED-12, treadmill-running trained for 8 weeks (TRA, 16 m/min, 60 min/day, 5 days/week, and treadmill-running trained for 8 weeks followed by 4 weeks of detraining (DET. At sacrifice, left ventricular myocytes were isolated enzymatically, and resting cell length, width, and cell shortening after stimulation at a frequency of 1 Hz (~25°C were measured. Cell length was greater in TRA than in SED-8 (161.30 ± 1.01 vs 156.10 ± 1.02 μm, P < 0.05, 667 vs 618 cells, respectively and remained larger after detraining. Cell width and volume were unaffected by either exercise training or detraining. Cell length to width ratio was higher in TRA than in SED-8 (8.50 ± 0.08 vs 8.22 ± 0.10, P < 0.05 and was maintained after detraining. Exercise training did not affect cell shortening, which was unchanged with detraining. TRA cells exhibited higher maximum velocity of shortening than SED-8 (102.01 ± 4.50 vs 82.01 ± 5.30 μm/s, P < 0.05, 70 cells per group, with almost complete regression after detraining. The maximum velocity of relengthening was higher in TRA cells than in SED-8 (88.20 ± 4.01 vs70.01 ± 4.80 μm/s, P < 0.05, returning to sedentary values with detraining. Therefore, exercise training affected left ventricle remodeling in SHR towards eccentric hypertrophy, which remained after detraining. It also improved single left ventricular myocyte contractile function, which was reversed by detraining.

  8. Sudden cardiac death and inherited channelopathy: the basic electrophysiology of the myocyte and myocardium in ion channel disease.

    Science.gov (United States)

    Martin, Claire A; Matthews, Gareth D K; Huang, Christopher L-H

    2012-04-01

    Mutations involving cardiac ion channels result in abnormal action potential formation or propagation, leading to cardiac arrhythmias. Despite the large impact on society of sudden cardiac death resulting from such arrhythmias, understanding of the underlying cellular mechanism is poor and clinical risk stratification and treatment consequently limited. Basic research using molecular techniques, as well as animal models, has proved extremely useful in improving our knowledge of inherited arrhythmogenic syndromes. This offers the practitioner tools to accurately diagnose rare disorders and provides novel markers for risk assessment and a basis for new strategies of treatment.

  9. Profile of L-type Ca2+ current and Na+/Ca2+ exchange current during cardiac action potential in ventricular myocytes

    Science.gov (United States)

    Banyasz, Tamas; Horvath, Balazs; Jian, Zhong; Izu, Leighton T.; Chen-Izu, Ye

    2011-01-01

    Objective The L-type Ca2+ current (ICa,L) and the Na+/Ca2+ exchange current (INCX) are major inward currents that shape the cardiac action potential (AP). Previously, the profile of these currents during AP was determined from voltage-clamp experiments that used Ca2+ buffer. In this study, we aimed to obtain direct experimental measurement of these currents during cardiac AP with Ca2+ cycling. Method A newly developed AP-clamp sequential dissection method was used to record ionic currents in guinea pig ventricular myocytes under a triad of conditions: using the cell’s own AP as the voltage command, using internal and external solutions that mimic the cell’s ionic composition and, importantly, no exogenous Ca2+ buffer was used. Results The nifedipine-sensitive current (INIFE), which is composed of ICa,L and INCX, revealed hitherto unreported features during AP with Ca2+ cycling in the cell. We identified two peaks in the current profile followed by a long residual current extending beyond the AP, coinciding with a residual depolarization. The second peak and the residual current become apparent only when Ca2+ is not buffered. Pharmacological dissection of INIFE using SEA0400 shows that ICa,L is dominant during phase-1&2 whereas INCX contributes significantly to the inward current at phase-3&4 of AP. Conclusion These data provide the first direct experimental visualization of ICa,L and INCX during cardiac AP and Ca2+ cycle. The residual current reported here can serve as a potential substrate for afterdepolarizations when increased under pathologic conditions. PMID:21884673

  10. β-Adrenergic stimulation increases Cav3.1 activity in cardiac myocytes through protein kinase A.

    Directory of Open Access Journals (Sweden)

    Yingxin Li

    Full Text Available The T-type Ca(2+ channel (TTCC plays important roles in cellular excitability and Ca(2+ regulation. In the heart, TTCC is found in the sinoatrial nodal (SAN and conduction cells. Cav3.1 encodes one of the three types of TTCCs. To date, there is no report regarding the regulation of Cav3.1 by β-adrenergic agonists, which is the topic of this study. Ventricular myocytes (VMs from Cav3.1 double transgenic (TG mice and SAN cells from wild type, Cav3.1 knockout, or Cav3.2 knockout mice were used to study β-adrenergic regulation of overexpressed or native Cav3.1-mediated T-type Ca(2+ current (I(Ca-T(3.1. I(Ca-T(3.1 was not found in control VMs but was robust in all examined TG-VMs. A β-adrenergic agonist (isoproterenol, ISO and a cyclic AMP analog (dibutyryl-cAMP significantly increased I(Ca-T(3.1 as well as I(Ca-L in TG-VMs at both physiological and room temperatures. The ISO effect on I(Ca-L and I(Ca-T in TG myocytes was blocked by H89, a PKA inhibitor. I(Ca-T was detected in control wildtype SAN cells but not in Cav3.1 knockout SAN cells, indicating the identity of I(Ca-T in normal SAN cells is mediated by Cav3.1. Real-time PCR confirmed the presence of Cav3.1 mRNA but not mRNAs of Cav3.2 and Cav3.3 in the SAN. I(Ca-T in SAN cells from wild type or Cav3.2 knockout mice was significantly increased by ISO, suggesting native Cav3.1 channels can be upregulated by the β-adrenergic (β-AR system. In conclusion, β-adrenergic stimulation increases I(Ca-T(3.1 in cardiomyocytes(, which is mediated by the cAMP/PKA pathway. The upregulation of I(Ca-T(3.1 by the β-adrenergic system could play important roles in cellular functions involving Cav3.1.

  11. Neonatal multiorgan failure due to ACAD9 mutation and complex I deficiency with mitochondrial hyperplasia in liver, cardiac myocytes, skeletal muscle, and renal tubules.

    Science.gov (United States)

    Leslie, Nancy; Wang, Xinjian; Peng, Yanyan; Valencia, C Alexander; Khuchua, Zaza; Hata, Jessica; Witte, David; Huang, Taosheng; Bove, Kevin E

    2016-03-01

    Complex I deficiency causes Leigh syndrome, fatal infant lactic acidosis, and neonatal cardiomyopathy. Mutations in more than 100 nuclear DNA and mitochondrial DNA genes miscode for complex I subunits or assembly factors. ACAD9 is an acyl-CoA dehydrogenase with a novel function in assembly of complex I; biallelic mutations cause progressive encephalomyopathy, recurrent Reye syndrome, and fatal cardiomyopathy. We describe the first autopsy in fatal neonatal lethal lactic acidosis due to mutations in ACAD9 that reduced complex I activity. We identified mitochondrial hyperplasia in cardiac myocytes, diaphragm muscle, and liver and renal tubules in formalin-fixed, paraffin-embedded tissue using immunohistochemistry for mitochondrial antigens. Whole-exome sequencing revealed compound heterozygous variants in the ACAD9 gene: c.187G>T (p.E63*) and c.941T>C (p.L314P). The nonsense mutation causes late infantile lethality; the missense variant is novel. Autopsy-derived fibroblasts had reduced complex I activity (53% of control) with normal activity in complexes II to IV, similar to reported cases of ACAD9 deficiency.

  12. Serum Positive for the Autoantibody against the β1-Adrenoceptor from Chinese Patients with Congestive Heart Failure Decreases Iss in Mouse Cardiac Myocytes

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    Yuan-yuan Wang

    2011-01-01

    Full Text Available Autoantibodies targeting the β1-adrenergic receptor (AAB-β1 display agonist-like effects, which may have a pathogenic role in the progression of heart failure. Here, we used the electrophysiological recordings to explore the effects of AAB-β1-positive serum from Chinese patients with heart failure on the activity of the peak transient outward potassium current (Ito and the end 50 ms steady-state potassium current (Iss in mouse cardiac myocytes. We found that the AAB-β1-positive serum had no effect on the activity of Ito, but it produced a decrease in the currents of Iss. A low concentration of positive serum (1/100 had a small inhibitory effect on Iss. However, positive serum at 1 : 10, 1 : 20, and 1 : 50 significantly decreased Iss. The concentration-dependence analysis showed that the EC50 of AAB-β1-positive serum was 1/60.24 and its nH was 2.86. It indicated that the AAB-β1 could inhibit Iss in mouse cardiomyocyte in a concentration-dependent manner.

  13. Effect of intracellular Ca2+ and action potential duration on L-type Ca2+ channel inactivation and recovery from inactivation in rabbit cardiac myocytes.

    Science.gov (United States)

    Altamirano, Julio; Bers, Donald M

    2007-07-01

    Ca(2+) current (I(Ca)) recovery from inactivation is necessary for normal cardiac excitation-contraction coupling. In normal hearts, increased stimulation frequency increases force, but in heart failure (HF) this force-frequency relationship (FFR) is often flattened or reversed. Although reduced sarcoplasmic reticulum Ca(2+)-ATPase function may be involved, decreased I(Ca) availability may also contribute. Longer action potential duration (APD), slower intracellular Ca(2+) concentration ([Ca(2+)](i)) decline, and higher diastolic [Ca(2+)](i) in HF could all slow I(Ca) recovery from inactivation, thereby decreasing I(Ca) availability. We measured the effect of different diastolic [Ca(2+)](i) on I(Ca) inactivation and recovery from inactivation in rabbit cardiac myocytes. Both I(Ca) and Ba(2+) current (I(Ba)) were measured. I(Ca) decay was accelerated only at high diastolic [Ca(2+)](i) (600 nM). I(Ba) inactivation was slower but insensitive to [Ca(2+)](i). Membrane potential dependence of I(Ca) or I(Ba) availability was not affected by [Ca(2+)](i) <600 nM. Recovery from inactivation was slowed by both depolarization and high [Ca(2+)](i). We also used perforated patch with action potential (AP)-clamp and normal Ca(2+) transients, using various APDs as conditioning pulses for different frequencies (and to simulate HF APD). Recovery of I(Ca) following longer APD was increasingly incomplete, decreasing I(Ca) availability. Trains of long APs caused a larger I(Ca) decrease than short APD at the same frequency. This effect on I(Ca) availability was exacerbated by slowing twitch [Ca(2+)](i) decline by approximately 50%. We conclude that long APD and slower [Ca(2+)](i) decline lead to cumulative inactivation limiting I(Ca) at high heart rates and might contribute to the negative FFR in HF, independent of altered Ca(2+) channel properties.

  14. Anandamide reduces intracellular Ca2+ concentration through suppression of Na+/Ca2+ exchanger current in rat cardiac myocytes.

    Directory of Open Access Journals (Sweden)

    Qian Li

    Full Text Available PURPOSE: Anandamide, one of the endocannabinoids, has been reported to exhibit cardioprotective properties, particularly in its ability to limit the damage produced by ischemia reperfusion injury. However, the mechanisms underlying the effect are not well known. This study is to investigate whether anandamide alter Na(+/Ca(2+ exchanger and the intracellular free Ca(2+ concentration ([Ca(2+]i. METHODS: Na(+/Ca(2+ exchanger current (I(NCX was recorded and analysed by using whole-cell patch-clamp technique and [Ca(2+]i was measured by loading myocytes with the fluorescent Ca(2+ indicator Fura-2/AM. RESULTS: We found that I(NCX was enhanced significantly after perfusion with simulated ischemic external solution; [Ca(2+]i was also significantly increased by simulated ischemic solution. The reversal potential of I(NCX was shifted to negative potentials in simulated ischemic external solution. Anandamide (1-100 nM failed to affect I(NCX and [Ca(2+]i in normal solution. However, anandamide (1-100 nM suppressed the increase in INCX in simulated ischemic external solution concentration-dependently and normalized INCX reversal potential. Furthermore, anandamide (100 nM significantly attenuated the increase in [Ca(2+]i in simulated ischemic solution. Blocking CB1 receptors with the specific antagonist AM251 (500 nM failed to affect the effects of anandamide on I(NCX and [Ca(2+]i in simulated ischemic solution. CB2 receptor antagonist AM630 (100 nM eliminated the effects of anandamide on I(NCX and [Ca(2+]i in simulated ischemic solution, and CB2 receptor agonist JWH133 (100 nM simulated the effects of anandamide that suppressed the increase in I(NCX and [Ca(2+]i in simulated ischemic solution. In addition, pretreatment with the Gi/o-specific inhibitor pertussis toxin (PTX, 500 ng/ml eliminated the effects of anandamide and JWH133 on I(NCX in simulated ischemic solution. CONCLUSIONS: Collectively, these findings suggest that anandamide suppresses calcium

  15. Cardiac Myocyte De Novo DNA Methyltransferases 3a/3b Are Dispensable for Cardiac Function and Remodeling after Chronic Pressure Overload in Mice.

    Directory of Open Access Journals (Sweden)

    Thomas G Nührenberg

    Full Text Available Recent studies reported altered DNA methylation in failing human hearts. This may suggest a role for de novo DNA methylation in the development of heart failure. Here, we tested whether cardiomyocyte-specific loss of de novo DNA methyltransferases Dnmt3a and Dnmt3b altered cardiac function and remodeling after chronic left ventricular pressure overload.Mice with specific ablation of Dnmt3a and Dnmt3b expression in cardiomyocytes were generated by crossing floxed Dnmt3afl and Dnmt3bfl alleles with mice expressing Cre recombinase under control of the atrial myosin light chain gene promoter. The efficacy of combined Dnmt3a/3b ablation (DKO was characterized on cardiomyocyte-specific genomic DNA and mRNA levels. Cardiac phenotyping was carried out without (sham or with left ventricular pressure overload induced by transverse aortic constriction (TAC. Under similar conditions, cardiac genome-wide transcriptional profiling was performed and DNA methylation levels of promoters of differentially regulated genes were assessed by pyrosequencing.DKO cardiomyocytes showed virtual absence of targeted Dnmt3a and Dnmt3b mRNA transcripts. Cardiac phenotyping revealed no significant differences between DKO and control mice under sham and TAC conditions. Transcriptome analyses identified upregulation of 44 and downregulation of 9 genes in DKO as compared with control sham mice. TAC mice showed similar changes with substantial overlap of regulated genes compared to sham. Promoters of upregulated genes were largely unmethylated in DKO compared to control mice.The absence of cardiac pathology in the presence of the predicted molecular phenotype suggests that de novo DNA methylation in cardiomyocytes is dispensable for adaptive mechanisms after chronic cardiac pressure overload.

  16. Evaluation of a novel integrated sensor system for synchronous measurement of cardiac vibrations and cardiac potentials.

    Science.gov (United States)

    Chuo, Yindar; Tavakolian, Kouhyar; Kaminska, Bozena

    2011-08-01

    The measurement of human body vibrations as a result of heart beating, simultaneously with cardiac potentials have been demonstrated in past studies to bring additional value to diagnostic cardiology through the detection of irregularities in the mechanical movement of the heart. The equipment currently available to the medical community is either large and bulky or difficult to synchronize. To address this problem, a novel integrated sensor system has been developed to record cardiac vibration and cardiac potential simultaneously and synchronously from a single compact site on the chest. The developed sensor system is lightweight, small in size, and suitable for mounting on active moving patients. The sensor is evaluated for its adequacy in measuring cardiac vibrations and potentials. In this evaluation, 45 independent signal recording are studied from 15 volunteers, and the morphology of the recorded signals are analyzed qualitatively (by visual inspection) and quantitatively (by computational methods) against larger devices used in established cardiac vibration studies (reference devices). It is found that the cardiac vibration signals acquired by the integrated sensor has 92.37% and 81.76% identically identifiable systolic and diastolic cardiac complexes, respectively, when compared to the cardiac vibration signals recorded simultaneously from the reference device. Further, the cardiac potential signals acquired by the integrated sensor show a high correlation coefficient of 0.8912 and a high estimated signal-to-noise-ratio of 22.00 dB when compared to the reference electrocardiograph (non-standard leads) acquired through a common clinical machine. The results suggest that the tiny, wearable, integrated sensor system that synchronously measures cardiac vibrations and cardiac potentials may be practical for use as an alternative or assistive cardiac diagnostic tool.

  17. Cell volume control in phospholemman (PLM) knockout mice: do cardiac myocytes demonstrate a regulatory volume decrease and is this influenced by deletion of PLM?

    Science.gov (United States)

    Bell, James R; Lloyd, David; Curl, Claire L; Delbridge, Lea M D; Shattock, Michael J

    2009-03-01

    In addition to modulatory actions on Na+-K+-ATPase, phospholemman (PLM) has been proposed to play a role in cell volume regulation. Overexpression of PLM induces ionic conductances, with 'PLM channels' exhibiting selectivity for taurine. Osmotic challenge of host cells overexpressing PLM increases taurine efflux and augments the cellular regulatory volume decrease (RVD) response, though a link between PLM and cell volume regulation has not been studied in the heart. We recently reported a depressed cardiac contractile function in PLM knockout mice in vivo, which was exacerbated in crystalloid-perfused isolated hearts, indicating that these hearts were osmotically challenged. To address this, the present study investigated the role of PLM in osmoregulation in the heart. Isolated PLM wild-type and knockout hearts were perfused with a crystalloid buffer supplemented with mannitol in a bid to prevent perfusate-induced cell swelling and maintain function. Accordingly, and in contrast to wild-type control hearts, contractile function was improved in PLM knockout hearts with 30 mM mannitol. To investigate further, isolated PLM wild-type and knockout cardiomyocytes were subjected to increasing hyposmotic challenges. Initial validation studies showed the IonOptix video edge-detection system to be a simple and accurate 'real-time' method for tracking cell width as a marker of cell size. Myocytes swelled equally in both genotypes, indicating that PLM, when expressed at physiological levels in cardiomyocytes, is not essential to limit water accumulation in response to a hyposmotic challenge. Interestingly, freshly isolated adult cardiomyocytes consistently failed to mount RVDs in response to cell swelling, adding to conflicting reports in the literature. A proposed perturbation of the RVD response as a result of the cell isolation process was not restored, however, with short-term culture in either adult or neonatal cardiomyocytes.

  18. Excitation-Contraction Coupling between Human Atrial Myocytes with Fibroblasts and Stretch Activated Channel Current: A Simulation Study

    Directory of Open Access Journals (Sweden)

    Heqing Zhan

    2013-01-01

    Full Text Available Myocytes have been regarded as the main objectives in most cardiac modeling studies and attracted a lot of attention. Connective tissue cells, such as fibroblasts (Fbs, also play crucial role in cardiac function. This study proposed an integrated myocyte-Isac-Fb electromechanical model to investigate the effect of Fbs and stretch activated ion channel current (Isac on cardiac electrical excitation conduction and mechanical contraction. At the cellular level, an active Fb model was coupled with a human atrial myocyte electrophysiological model (including Isac and a mechanical model. At the tissue level, electrical excitation conduction was coupled with an elastic mechanical model, in which finite difference method (FDM was used to solve the electrical excitation equations, while finite element method (FEM was used for the mechanics equations. The simulation results showed that Fbs and Isac coupling caused diverse effects on action potential morphology during repolarization, depolarized the resting membrane potential of the human atrial myocyte, slowed down wave propagation, and decreased strains in fibrotic tissue. This preliminary simulation study indicates that Fbs and Isac have important implications for modulating cardiac electromechanical behavior and should be considered in future cardiac modeling studies.

  19. Integrated imaging of cardiac anatomy, physiology, and viability.

    Science.gov (United States)

    Arrighi, James A

    2009-03-01

    Technologic developments in imaging will have a significant impact on cardiac imaging over the next decade. These advances will permit more detailed assessment of cardiac anatomy, complex assessment of cardiac physiology, and integration of anatomic and physiologic data. The distinction between anatomic and physiologic imaging is important. For assessing patients with known or suspected coronary artery disease, physiologic and anatomic imaging data are complementary. The strength of anatomic imaging rests in its ability to detect the presence of disease, whereas physiologic imaging techniques assess the impact of disease, such as whether a coronary atherosclerotic lesion limits myocardial blood flow. Research indicates that physiologic data are more prognostically important than anatomic data, but both may be important in patient management decisions. Integrated cardiac imaging is an evolving field, with many potential indications. These include assessment of coronary stenosis, myocardial viability, anatomic and physiologic characterization of atherosclerotic plaque, and advanced molecular imaging.

  20. In silico coronary wave intensity analysis: application of an integrated one-dimensional and poromechanical model of cardiac perfusion.

    Science.gov (United States)

    Lee, Jack; Nordsletten, David; Cookson, Andrew; Rivolo, Simone; Smith, Nicolas

    2016-12-01

    Coronary wave intensity analysis (cWIA) is a diagnostic technique based on invasive measurement of coronary pressure and velocity waveforms. The theory of WIA allows the forward- and backward-propagating coronary waves to be separated and attributed to their origin and timing, thus serving as a sensitive and specific cardiac functional indicator. In recent years, an increasing number of clinical studies have begun to establish associations between changes in specific waves and various diseases of myocardium and perfusion. These studies are, however, currently confined to a trial-and-error approach and are subject to technological limitations which may confound accurate interpretations. In this work, we have developed a biophysically based cardiac perfusion model which incorporates full ventricular-aortic-coronary coupling. This was achieved by integrating our previous work on one-dimensional modelling of vascular flow and poroelastic perfusion within an active myocardial mechanics framework. Extensive parameterisation was performed, yielding a close agreement with physiological levels of global coronary and myocardial function as well as experimentally observed cumulative wave intensity magnitudes. Results indicate a strong dependence of the backward suction wave on QRS duration and vascular resistance, the forward pushing wave on the rate of myocyte tension development, and the late forward pushing wave on the aortic valve dynamics. These findings are not only consistent with experimental observations, but offer a greater specificity to the wave-originating mechanisms, thus demonstrating the value of the integrated model as a tool for clinical investigation.

  1. Cardiac power integral: a new method for monitoring cardiovascular performance.

    Science.gov (United States)

    Rimehaug, Audun E; Lyng, Oddveig; Nordhaug, Dag O; Løvstakken, Lasse; Aadahl, Petter; Kirkeby-Garstad, Idar

    2013-11-01

    Cardiac power (PWR) is the continuous product of flow and pressure in the proximal aorta. Our aim was to validate the PWR integral as a marker of left ventricular energy transfer to the aorta, by comparing it to stroke work (SW) under multiple different loading and contractility conditions in subjects without obstructions in the left ventricular outflow tract. Six pigs were under general anesthesia equipped with transit time flow probes on their proximal aortas and Millar micromanometer catheters in their descending aortas to measure PWR, and Leycom conductance catheters in their left ventricles to measure SW. The PWR integral was calculated as the time integral of PWR per cardiac cycle. SW was calculated as the area encompassed by the pressure-volume loop (PV loop). The relationship between the PWR integral and SW was tested during extensive mechanical and pharmacological interventions that affected the loading conditions and myocardial contractility. The PWR integral displayed a strong correlation with SW in all pigs (R (2) > 0.95, P integral relationship was similar among all six animals, whereas loading and contractility conditions tended to affect the slope. The PWR integral followed SW and appeared to be a promising parameter for monitoring the energy transferred from the left ventricle to the aorta. This conclusion motivates further studies to determine whether the PWR integral can be evaluated using less invasive methods, such as echocardiography combined with a radial artery catheter.

  2. Time-resolved fluorescence spectroscopy investigation of the effect of 4-hydroxynonenal on endogenous NAD(P)H in living cardiac myocytes

    Science.gov (United States)

    Chorvatova, Alzbeta; Aneba, Swida; Mateasik, Anton; Chorvat, Dusan; Comte, Blandine

    2013-06-01

    Lipid peroxidation is a major biochemical consequence of the oxidative deterioration of polyunsaturated lipids in cell membranes and causes damage to membrane integrity and loss of protein function. 4-hydroxy-2-nonenal (HNE), one of the most reactive products of n-6 polyunsaturated fatty acid peroxidation of membrane phospholipids, has been shown to be capable of affecting both nicotinamide adenine dinucleotide (phosphate) reduced [NAD(P)H] as well as NADH production. However, the understanding of its effects in living cardiac cells is still lacking. Our goal was to therefore investigate HNE effects on NAD(P)H noninvasively in living cardiomyocytes. Spectrally resolved lifetime detection of endogenous fluorescence, an innovative noninvasive technique, was employed. Individual fluorescence components were resolved by spectral linear unmixing approach. Gathered results revealed that HNE reduced the amplitude of both resolved NAD(P)H components in a concentration-dependent manner. In addition, HNE increased flavoprotein fluorescence and responsiveness of the NAD(P)H component ratio to glutathione reductase (GR) inhibitor. HNE also increased the percentage of oxidized nucleotides and decreased maximal NADH production. Presented data indicate that HNE provoked an important cell oxidation by acting on NAD(P)H regulating systems in cardiomyocytes. Understanding the precise role of oxidative processes and their products in living cells is crucial for finding new noninvasive tools for biomedical diagnostics of pathophysiological states.

  3. Oxidative stress decreases microtubule growth and stability in ventricular myocytes

    OpenAIRE

    Drum, BML; Yuan, C.; Li, L; Liu, Q.; Wordeman, L; Santana, LF

    2016-01-01

    © 2016 Elsevier Ltd.Microtubules (MTs) have many roles in ventricular myocytes, including structural stability, morphological integrity, and protein trafficking. However, despite their functional importance, dynamic MTs had never been visualized in living adult myocytes. Using adeno-associated viral vectors expressing the MT-associated protein plus end binding protein 3 (EB3) tagged with EGFP, we were able to perform live imaging and thus capture and quantify MT dynamics in ventricular myocyt...

  4. MCI-154对大鼠心肌细胞的变力作用%Inotropic effects of MCI-154 on rat cardiac myocytes

    Institute of Scientific and Technical Information of China (English)

    陈还珍; 崔香丽; 赵画晨; 赵录英; 吕吉元; 吴博威

    2004-01-01

    Calcium sensitizers exert positive inotropic effects without increasing intracellular Ca2+. Thus, they avoid the undesired effects of Ca2+ overload such as arrhythmias and cell injury, but most of them may impair myocyte relaxation. However, MCI-154, also a calcium sensitizer, has no impairment to cardiomyocyte relaxation. To clarify the underlying mechanisms, we examined the effects of MCI-154 on Ca2+ transient and cell contraction using ion imaging system, and its influence on L-type Ca2+ current and Na+/Ca2+ exchange current with patch clamp technique in rat ventricular myocytes as well. The results showed that: (1) MCI-154 (1~100 μmol/L) had no effect on L-type Ca2+ current; (2) MCI-154 concentration-dependently increased cell shortening from 5.00± 1.6 μm of control to 6.2± 1.6 μm at 1 μmol/L,8.7±1.6 μm at 10 μmol/L and 14.0±1.4 μm at 100 μmol/L, respectively, with a slight increase in Ca2+ transient amplitude and an abbreviation of Ca2+ transient restore kinetics assessed by time to 50% restore (TR50) and time to 90% restore (TR90); (3) MCI-154 dosedependently increased the electrogenic Na+/Ca2+ exchange current both in the inward and the outward directions in rat ventricular myocytes. These results indicate that MCI-154 exerted a positive inotropic action without impairing myocyte relaxation. The stimulation of inward Na+/Ca2+ exchange current may accelerate the Ca2+ effiux, leading to abbreviations of TR50 and TR90 in rat myocytes. The findings suggest that the improvement by MCI-154 of myocyte relaxation is attributed to the forward mode of Na+/Ca2+ exchange.%钙增敏剂具有正性肌力作用,同时不增加细胞内钙浓度,因此可避免导致心律失常和最终心肌细胞死亡的钙超载.然而大部分钙增敏剂对心肌舒张功能有损害作用.MCI-154是一种钙增敏剂,但不损害舒张功能.为阐明其变力作用机制,我们应用离子成像技术研究了MCI-154对分离的单个大鼠心室肌细胞钙瞬变和

  5. The angiotensin type 1 receptor activates extracellular signal-regulated kinases 1 and 2 by G protein-dependent and -independent pathways in cardiac myocytes and langendorff-perfused hearts

    DEFF Research Database (Denmark)

    Aplin, Mark; Christensen, Gitte Lund; Schneider, Mikael;

    2007-01-01

    The angiotensin II (AngII) type 1 receptor (AT(1)R) has been shown to activate extracellular signal-regulated kinases 1 and 2 (ERK1/2) through G proteins or G protein-independently through beta-arrestin2 in cellular expression systems. As activation mechanisms may greatly influence the biological...... effects of ERK1/2 activity, differential activation of the AT(1)R in its native cellular context could have important biological and pharmacological implications. To examine if AT(1)R activates ERK1/2 by G protein-independent mechanisms in the heart, we used the [Sar(1), Ile(4), Ile(8)]-AngII ([SII] Ang......II) analogue in native preparations of cardiac myocytes and beating hearts. We found that [SII] AngII does not activate G(q)-coupling, yet stimulates the beta-arrestin2-dependent ERK1/2. The G(q)-activated pool of ERK1/2 rapidly translocates to the nucleus, while the beta-arrestin2-scaffolded pool remains...

  6. Assessment of cardiac sympathetic nerve integrity with positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Raffel, David M. E-mail: raffel@umich.edu; Wieland, Donald M

    2001-07-01

    The autonomic nervous system plays a critical role in the regulation of cardiac function. Abnormalities of cardiac innervation have been implicated in the pathophysiology of many heart diseases, including sudden cardiac death and congestive heart failure. In an effort to provide clinicians with the ability to regionally map cardiac innervation, several radiotracers for imaging cardiac sympathetic neurons have been developed. This paper reviews the development of neuronal imaging agents and discusses their emerging role in the noninvasive assessment of cardiac sympathetic innervation.

  7. Responses of hypertrophied myocytes to reactive species: implications for glycolysis and electrophile metabolism.

    Science.gov (United States)

    Sansbury, Brian E; Riggs, Daniel W; Brainard, Robert E; Salabei, Joshua K; Jones, Steven P; Hill, Bradford G

    2011-04-15

    During cardiac remodelling, the heart generates higher levels of reactive species; yet an intermediate 'compensatory' stage of hypertrophy is associated with a greater ability to withstand oxidative stress. The mechanisms underlying this protected myocardial phenotype are poorly understood. We examined how a cellular model of hypertrophy deals with electrophilic insults, such as would occur upon ischaemia or in the failing heart. For this, we measured energetics in control and PE (phenylephrine)-treated NRCMs (neonatal rat cardiomyocytes) under basal conditions and when stressed with HNE (4-hydroxynonenal). PE treatment caused hypertrophy as indicated by augmented atrial natriuretic peptide and increased cellular protein content. Hypertrophied myocytes demonstrated a 2.5-fold increase in ATP-linked oxygen consumption and a robust augmentation of oligomycin-stimulated glycolytic flux and lactate production. Hypertrophied myocytes displayed a protected phenotype that was resistant to HNE-induced cell death and a unique bioenergetic response characterized by a delayed and abrogated rate of oxygen consumption and a 2-fold increase in glycolysis upon HNE exposure. This augmentation of glycolytic flux was not due to increased glucose uptake, suggesting that electrophile stress results in utilization of intracellular glycogen stores to support the increased energy demand. Hypertrophied myocytes also had an increased propensity to oxidize HNE to 4-hydroxynonenoic acid and sustained less protein damage due to acute HNE insults. Inhibition of aldehyde dehydrogenase resulted in bioenergetic collapse when myocytes were challenged with HNE. The integration of electrophile metabolism with glycolytic and mitochondrial energy production appears to be important for maintaining myocyte homoeostasis under conditions of increased oxidative stress.

  8. Liberación de endotelina-1 por angiotensina ll en miocitos cardíacos aislados Angiotensin II-induced endothelin-1 release in cardiac myocytes

    Directory of Open Access Journals (Sweden)

    María C. Villa-Abrille

    2006-06-01

    Full Text Available Muchos de los efectos de la angiotensina II (Ang II son mediados en realidad por la acción de endotelina (ET endógena liberada y/o producida en respuesta a la Ang II. En este trabajo evaluamos la interacción Ang II/ET-1, sus consecuencias en la contractilidad cardíaca y el papel de las especies reactivas del oxígeno (EROs. Se usaron cardiomiocitos aislados de gato. La Ang II, 1 nM, produjo un efecto inotrópico positivo (EIP de 31.8±3.8% que fue cancelado por inhibición de los receptores AT1, de los receptores de ET, del intercambiador Na+/H+ (NHE, del modo inverso del intercambiador Na+/Ca2+ (NCX o por el secuestro de EROs. La Ang II, 100 nM, produjo un EIP de 70.5±7.6% que fue cancelado por inhibición de los receptores AT1 y bloqueado en parte por inhibición de los receptores de ET, del NHE, del modo inverso del NCX o por el secuestro de EROs. La Ang II, 1 nM, incrementó el ARNm de la preproET-1 lo cual fue anulado por el bloqueo de los receptores AT1. Los resultados permiten concluir que el EIP de la Ang II es debido a la acción de la ET-1 endógena liberada/formada por la Ang II. La ET-1 produce: estimulación del NHE, activación del modo inverso del NCX y un consecuente EIP. Dentro de esta cascada también participarían los EROs.Many of the effects thought to be due to angiotensin II (Ang II are due to the release/formation of endothelin (ET. We tested whether Ang II elicits its positive inotropic effect (PIE by the action of endogenous ET-1 and the role played by the reactive oxygen species (ROS in this mechanism. Experiments were performed in cat isolated ventricular myocytes in which sarcomere shortening (SS was measured to asses contractility after pharmacological interventions and the effect of Ang II on inotropism were analyzed. Ang II 1 nM increased SS by 31.8±3.8% (p<0.05. This PIE was cancelled by AT1 receptor blockade, by ET-1 receptors blockade, by Na+/H+ exchanger (NHE inhibition, by reverse mode Na+/Ca2

  9. The lipid peroxidation product 4-hydroxy-trans-2-nonenal causes protein synthesis in cardiac myocytes via activated mTORC1-p70S6K-RPS6 signaling.

    Science.gov (United States)

    Calamaras, Timothy D; Lee, Charlie; Lan, Fan; Ido, Yasuo; Siwik, Deborah A; Colucci, Wilson S

    2015-05-01

    Reactive oxygen species (ROS) are elevated in the heart in response to hemodynamic and metabolic stress and promote hypertrophic signaling. ROS also mediate the formation of lipid peroxidation-derived aldehydes that may promote myocardial hypertrophy. One lipid peroxidation by-product, 4-hydroxy-trans-2-nonenal (HNE), is a reactive aldehyde that covalently modifies proteins thereby altering their function. HNE adducts directly inhibit the activity of LKB1, a serine/threonine kinase involved in regulating cellular growth in part through its interaction with the AMP-activated protein kinase (AMPK), but whether this drives myocardial growth is unclear. We tested the hypothesis that HNE promotes myocardial protein synthesis and if this effect is associated with impaired LKB1-AMPK signaling. In adult rat ventricular cardiomyocytes, exposure to HNE (10 μM for 1h) caused HNE-LKB1 adduct formation and inhibited LKB1 activity. HNE inhibited the downstream kinase AMPK, increased hypertrophic mTOR-p70S6K-RPS6 signaling, and stimulated protein synthesis by 27.1 ± 3.5%. HNE also stimulated Erk1/2 signaling, which contributed to RPS6 activation but was not required for HNE-stimulated protein synthesis. HNE-stimulated RPS6 phosphorylation was completely blocked using the mTOR inhibitor rapamycin. To evaluate if LKB1 inhibition by itself could promote the hypertrophic signaling changes observed with HNE, LKB1 was depleted in adult rat ventricular myocytes using siRNA. LKB1 knockdown did not replicate the effect of HNE on hypertrophic signaling or affect HNE-stimulated RPS6 phosphorylation. Thus, in adult cardiac myocytes HNE stimulates protein synthesis by activation of mTORC1-p70S6K-RPS6 signaling most likely mediated by direct inhibition of AMPK. Because HNE in the myocardium is commonly increased by stimuli that cause pathologic hypertrophy, these findings suggest that therapies that prevent activation of mTORC1-p70S6K-RPS6 signaling may be of therapeutic value.

  10. Trichostatin A induces a unique set of microRNAs including miR-129-5p that blocks cyclin-dependent kinase 6 expression and proliferation in H9c2 cardiac myocytes.

    Science.gov (United States)

    Majumdar, Gipsy; Raghow, Rajendra

    2016-04-01

    The pan-histone deacetylase inhibitor (HDACI), trichostatin A (TSA), was shown to normalize interleukin-18-induced cardiac hypertrophy in vivo and in vitro; evidently, this occurred via epigenetic mechanisms that profoundly altered cardiac gene expression (Majumdar et al. in, Physiol Genom, 43: 1392, 2011; BMC Genom, 13: 709, 2012). Here, we tested the hypothesis that TSA-induced changes in chromatin architecture also led to altered expression of microRNAs that in turn, contributed to the unique transcriptome of cardiac myocytes exposed to the HDACI. Using miRCURY LNA™ Universal microRNA PCR system, we demonstrate that H9c2 cells exposed to TSA for 6 and 24 h elicited differential expression of 19 and 16 microRNAs, respectively. H9c2 cells incubated in medium-containing 100 nM of TSA elicited a rapid and robust induction of miR-129-5p. Enhanced expression of miR-129-5p was also observed in the hearts of TSA-treated mice. Induction of miR-129-5p in H9c2 cells was accompanied by reduced expression of its direct target, cyclin-dependent kinase 6 (CDK6) that is a key regulator of cell cycle. Using cell division-dependent dilution of Cell Trace™ violet measurements we showed that concomitant induction of miR-129-5p and reduced CDK6 expression were mechanistically involved in TSA-induced inhibition of proliferation of H9c2 cells. Consistent with this scenario, cells expressing an antagomiR of miR-129-5p were resistant to the anti-proliferative actions of TSA. These data indicate that although TSA treatment led to altered expression of several microRNAs, the overarching action of TSA (i.e., inhibition of cell division) in H9c2 cells was achieved via miR-129-5p.

  11. Technetium-99m labeled 1-(4-fluorobenzyl)-4-(2-mercapto-2-methyl-4-azapentyl)-4- (2-mercapto-2-methylp ropylamino)-piperidine and iodine-123 metaiodobenzylguanidine for studying cardiac adrenergic function: a comparison of the uptake characteristics in vascular smooth muscle cells and neonatal cardiac myocytes, and an investigation in rats

    Energy Technology Data Exchange (ETDEWEB)

    Samnick, Samuel E-mail: rassam@uniklinik-saarland.de; Scheuer, Claudia; Muenks, Sven; El-Gibaly, Amr M.; Menger, Michael D.; Kirsch, Carl-Martin

    2004-05-01

    In developing technetium-99m-based radioligands for in vivo studies of cardiac adrenergic neurons, we compared the uptake characteristics of the {sup 99m}Tc-labeled 1-(4-fluorobenzyl)-4-(2-mercapto-2-methyl-4-azapentyl)-4- (2-mercapto-2-methylpropylamino)-piperidine ({sup 99m}Tc-FBPBAT) with those of the clinically established meta-[{sup 123}I]iodobenzylguanidine ({sup 123}I-MIBG) in rat vascular smooth muscle cells and neonatal cardiac myocytes. Furthermore, the cardiac and extracardiac uptake of both radiopharmaceuticals was assessed in intact rats and in rats pretreated with various {alpha}- and {beta}-adrenoceptor drugs, and adrenergic reuptake blocking agents. The uptake of {sup 99m}Tc-FBPBAT and {sup 123}I-MIBG into vascular smooth muscle cells and neonatal cardiac myocytes was rapid; more than 85% of the radioactivity accumulation into the cells occurring within the first 3 minutes. Radioactivity uptake after a 60-minute incubation at 37 degree sign C (pH 7.4) varied from 15% to 65% of the total loaded activity per million cells. In all cases, {sup 99m}Tc-FBPBAT showed the higher uptake, relative to {sup 123}I-MIBG, at any given cell concentration. The cellular uptake of {sup 99m}Tc-FBPBAT was lower at 4 degree sign C and 20 degree sign C than at 37 degree sign C. In contrast, the {sup 123}I-MIBG uptake was only slightly temperature dependent. Inhibition experiments confirmed that the cellular uptake of {sup 123}I-MIBG is mediated by the uptake-I carrier, whereas {alpha}{sub 1}- and {beta}{sub 1}-adrenoceptors were predominantly involved in the uptake of {sup 99m}Tc-FBPBAT into the cardiovascular tissues. Biodistribution studies in rats showed that {sup 99m}Tc-FBPBAT accumulated in myocardium after intravenous injection. Radioactivity in rat heart amounted to 2.32% and 1.91% of the injected dose per gram at 15 and 60 minutes postinjection, compared with 3.10% and 2.21% injected dose per gram of tissue (%ID/g) in the experiment with {sup 123}I

  12. Integration and communication for the continuity of cardiac care (I4C)

    NARCIS (Netherlands)

    Bemmel, J.H. van; Ginneken, A.M. van; Stam, H.; Assanelli, D.; Macfarlane, P.W.; Maglaveras, N.; Rubel, P.; Zeelenberg, C.; Zywietz, Chr.

    1998-01-01

    The project I4C (Integration and Communication for the Continuity of Cardiac Care) is carried out for the advancement of cardiac care, from prevention to follow-up. The goals of I4C are: (1) integrated access to patient data, wherever they are stored; (2) support of evidence-based care; (3) consiste

  13. Cross-bridge cycling gives rise to spatiotemporal heterogeneity of dynamic subcellular mechanics in cardiac myocytes probed with atomic force microscopy.

    Science.gov (United States)

    Azeloglu, Evren U; Costa, Kevin D

    2010-03-01

    To study how the dynamic subcellular mechanical properties of the heart relate to the fundamental underlying process of actin-myosin cross-bridge cycling, we developed a novel atomic force microscope elastography technique for mapping spatiotemporal stiffness of isolated, spontaneously beating neonatal rat cardiomyocytes. Cells were indented repeatedly at a rate close but unequal to their contractile frequency. The resultant changes in pointwise apparent elastic modulus cycled at a predictable envelope frequency between a systolic value of 26.2 +/- 5.1 kPa and a diastolic value of 7.8 +/- 4.1 kPa at a representative depth of 400 nm. In cells probed along their major axis, spatiotemporal changes in systolic stiffness displayed a heterogeneous pattern, reflecting the banded sarcomeric structure of underlying myofibrils. Treatment with blebbistatin eliminated contractile activity and resulted in a uniform apparent modulus of 6.5 +/- 4.8 kPa. This study represents the first quantitative dynamic mechanical mapping of beating cardiomyocytes. The technique provides a means of probing the micromechanical effects of disease processes and pharmacological treatments on beating cardiomyocytes, providing new insights and relating subcellular cardiac structure and function.

  14. 钙调蛋白激酶Ⅱ抑制剂对肥厚心肌细胞的影响%The effects of calmodulin kinase Ⅱ inhibitor on hypertrophic cardiac myocytes

    Institute of Scientific and Technical Information of China (English)

    柯俊; 陈锋; 肖幸; 戴木森; 王晓萍; 陈兵; 陈敏; 张存泰

    2012-01-01

    目的 观察钙调蛋白激酶Ⅱ(CaMKⅡ)抑制剂KN-93对肥厚心肌细胞L型钙电流(ICa,L)及细胞内钙离子浓度([Ca2+]i)的影响.方法 选取雌性新西兰大白兔48只,随机(随机数字法)分为4组:假手术组(sham组)、心肌肥厚组(LVH组)、心肌肥厚+KN-93组(KN-93组)、心肌肥厚+KN-92组(KN-92组),每组12只,通过缩窄腹主动脉制备兔心肌肥厚模型,Sham组仅游离腹主动脉未进行缩窄.8周后,采用胶原酶消化法分离单个心肌细胞,应用穿孔膜片钳技术记录L型钙电流(ICa,L);应用钙荧光指示剂Fura-2/AM结合图像分析技术测定各组心肌细胞内[Ca2+]i.结果 8周后,心肌肥厚模型建立成功.在0 mV时LVH组、Sham组的峰值ICa.L分另为(1.38±0.3)nA、(0.87±0.1)nA(P<0.01,n=12),电流密度分别为(6.7±1.0)pA/pF、(6.3 ±0.7)pA/pF(P>0.05,n=12).当KN-92及KN-93在浓度为0.5μmol/L时,可分别使肥厚心肌细胞0 mV时的峰值ICa,L降低(9.4±2.8)%、(10.5±3)%(P>0.05,n=12);当浓度增至1 μmol/L时,其峰值ICa,L降低程度分别为(13.4±3.7)%、(40±4.9)%(P<0.01,n=12).Sham组、LVH组、KN-92组及KN-93组中心肌细胞[Ca2+]i分别为(98.0±12.3)nmol/L、(154.0±26.2)nmol/L、(147.0±29.6)nmol/L和(108.0±21.2)nmol/L.结论 CaMKⅡ特异性抑制剂KN-93可有效抑制肥厚心肌细胞ICa.L,减轻细胞内钙超载,这可能是其抗肥厚心肌室性心律失常发生的主要细胞电生理机制.%Objective To investigate the effect of the calmodulin kinase Ⅱ Inhibitor KN-93 on L-typecalcium current(ICa,L)and intracellular calcium concentration([Ca2+]i)in hypertrophic cardiac myocytes.Methods Forty-eight female New Zealand white rabbits were randomized(random number)into four groups(12 animals in each group):the sham operation group(sham group),the left ventricular hypertrophy group(LVH group),the myocardial hypertrophy + KN-93 group(KN-93 group),and the myocardial hypertrophy + KN-92 group(KN-92 group).Myocardial hypertrophy in

  15. 运动性心肌肥厚中PKC信号通路研究进展%Advance of PKC Signaling Pathway in Exercise -induced Cardiac Myocyte Hypertrophy

    Institute of Scientific and Technical Information of China (English)

    柳华; 杨翼

    2011-01-01

    心肌肥厚是心脏受到刺激后的一种代偿反应。心肌的生理性肥厚可提高心脏机能,但病理性肥厚则会引起心血管疾病心律失常发病和死亡,亦是运动员发生猝死的原因之一。明确运动性心肌肥厚的机制,可为保护运动员心脏提供理论依据。目前为止,形成心肌肥厚的信号通路包括PKC、蛋白激酶B(Akt)、钙调神经磷酸酶(CaM)、丝裂原活化蛋白激酶MAPK、酪氨酸激酶受体gp130/STAT、牵拉敏感离子通道以及细胞骨架等。其中PKC途径是调控心肌细胞的生长、分化以及肥厚的过程中信号转导通路的关键环节。心肌细胞可通过Gq/PLC/Ca2+/PKC、PKC/MAPK、PKC/NF-κB等相关途径促使活化晚期反应基因使心肌肥厚。在运动过程中,形成的生理性肥厚主要通过AkffmTOR途径。心肌细胞的机械牵拉亦可以通过PKC信号传导促使肥厚。PKC包括13种亚型,各亚型对心脏的作用不一。PKCa对多次运动后心肌有保护作用;PKCβ1对心肌可能有保护作用,B2则是相反的作用;PKC8有利于心肌细胞的适应;PKCs对心肌的保护作用亦有可能有相反的作用;PKCζ促使心肌肥厚。%Myocardial hypertrophy is a compensatory response after the heart stimulation. Myocardial physio- logic hypertrophy can improve heart function, but pathological hypertrophy may cause cardiovascular disease as onset of arrhythmia and death, and also one of the causes of sudden death in athletes. The clearing mecha- nism of exercise -induced cardiac hypertrophy can provide a theoretical basis for the protection of athlete' s heart. So far, formation of myocardial hypertrophy signaling pathways includes PKC, protein kinase B ( Akt), calcineurin ( CaM), activation of the mitogen - activated protein kinase MAPK, tyrosine kinase re- ceptor gpl30/STAT, and the stretch of sensitive ion channels and cytoskeletal etc.. The PKC pathway is the

  16. Modes of induced cardiac arrest: hyperkalemia and hypocalcemia - Literature review

    OpenAIRE

    Oliveira,Marcos Aurélio Barboza de; Brandi, Antônio Carlos; dos Santos, Carlos Alberto; Botelho, Paulo Henrique Husseini; Cortez, José Luis Lasso; Braile, Domingo Marcolino

    2014-01-01

    The entry of sodium and calcium play a key effect on myocyte subjected to cardiac arrest by hyperkalemia. They cause cell swelling, acidosis, consumption of adenosine triphosphate and trigger programmed cell death. Cardiac arrest caused by hypocalcemia maintains intracellular adenosine triphosphate levels, improves diastolic performance and reduces oxygen consumption, which can be translated into better protection to myocyte injury induced by cardiac arrest.

  17. An integrated bioimpedance—ECG gating technique for respiratory and cardiac motion compensation in cardiac PET

    Science.gov (United States)

    Koivumäki, Tuomas; Nekolla, Stephan G.; Fürst, Sebastian; Loher, Simone; Vauhkonen, Marko; Schwaiger, Markus; Hakulinen, Mikko A.

    2014-10-01

    Respiratory motion may degrade image quality in cardiac PET imaging. Since cardiac PET studies often involve cardiac gating by ECG, a separate respiratory monitoring system is required increasing the logistic complexity of the examination, in case respiratory gating is also needed. Thus, we investigated the simultaneous acquisition of both respiratory and cardiac gating signals using II limb lead mimicking electrode configuration during cardiac PET scans of 11 patients. In addition to conventional static and ECG-gated images, bioimpedance technique was utilized to generate respiratory- and dual-gated images. The ability of the bioimpedance technique to monitor intrathoracic respiratory motion was assessed estimating cardiac displacement between end-inspiration and -expiration. The relevance of dual gating was evaluated in left ventricular volume and myocardial wall thickness measurements. An average 7.6  ±  3.3 mm respiratory motion was observed in the study population. Dual gating showed a small but significant increase (4 ml, p = 0.042) in left ventricular myocardial volume compared to plain cardiac gating. In addition, a thinner myocardial wall was observed in dual-gated images (9.3  ±  1.3 mm) compared to cardiac-gated images (11.3  ±  1.3 mm, p = 0.003). This study shows the feasibility of bioimpedance measurements for dual gating in a clinical setting. The method enables simultaneous acquisition of respiratory and cardiac gating signals using a single device with standard ECG electrodes.

  18. 利多卡因对家兔左右心室外膜心肌细胞电不均一性的影响%Effects of Lidocaine on Cardiac Electrical Heterogeneity of Left and Right Subepicardial Myocytes in Ventricular Walls of Rabbits

    Institute of Scientific and Technical Information of China (English)

    周军; 王腾; 胡河; 曹红; 秦牧

    2012-01-01

    addition (compared with lidocaine group, P<0. 05 and 0. 01, respectively). Lidocaine shifted upward the I-V curves of In, of both left and right subepicardial myocytes, but lifted outstandingly the I-V curve of Ina of right subepicardial myocytes on the top of all I-V curves. Moreover, lidocaine changed the peak potential of Ina from -20 to -10 mV in left and right subepicardial myocytes. Conclusion: Lidocaine could completely elicited the cardiac electrical heterogeneity of left and right subepicardial myocytes in ventricular walls of rabbits, which attributed to AP and Ina of right subepicardial myocytes which was attenuated more obviously than that of left subepicardial myocytes by administrating lidocaine.%目的:探讨利多卡因对家兔左、右心室心外膜心肌细胞动作电位和钠电流(INa)的影响,阐明利多卡因引起左、右心室心外膜心肌细胞电不均一性机制.方法:酶解法分离家兔单个左、右心室心外膜心肌细胞,全细胞膜片钳技术记录左、右心室心外膜心肌细胞动作电位和INa在应用利多卡因前后变化.结果:在电流钳制下,对照组中的左、右心室心外膜心肌细胞上记录动作电位都具有典型的0至4期的形态,2相平台期有心外膜心肌细胞特有的穹窿样凸起;但在利多卡因组,左、右心室心外膜心肌细胞动作均明显地失去2相平台期穹窿样凸起和高度,右室心外膜心肌细胞动作电位失去2相平台期立即复极,形似三角形,左、右心室心外膜心肌细胞动作电位的幅度(APA)和复极化50%和90%(APD50和APD90)均明显减少(P<0.05),且右室心外膜心肌细胞的APA和APD50以及APD90受利多卡因影响后减小最为严重(P<0.05或0.01).通过电压钳制方式,利多卡因使左、右心室心外膜心肌细胞的INa在各个指令电位下明显减小,而且右室心外膜心肌细胞INa减小的幅度要显著强于左室心外膜心肌细胞INa的减小幅度,当钳制电压为-20 mV

  19. Effects of Adiponectin on Cell Oxidative Stress and Apoptosis in Human Cardiac Myocytes Cultured with High Glucose%脂联素对高糖环境心肌细胞氧化应激及凋亡的影响

    Institute of Scientific and Technical Information of China (English)

    李美蓉; 李兴

    2012-01-01

    Objective To establish a myocardial cell oxidative stress model by cultivating human cardiac myocytes (HCM) in a high glucose environment, and to observe if there is a protective role of adiponectin (ADPN) on the oxidative stress and apoplosis of myocardial cells, and reveals the protection mechanism of the adiponectin. Methods The in vitro cultured HCM were divided into three groups;the control group, high glucose group, high glucose + adiponectin group, and these cells were cultured 24, 48, 72hours respectively. Then we observed the morphological change of the HCM under the inverted microscope and evaluated the level of superoxide dis-mutase ( SOD) by the xanthineoxidase method. The level of malondialdehyde ( MDA) was detected by benzodiazepines acid method. The expression of adaptin ( P66Shc) and heme oxygenase - 1 ( Ho - 1) in three time points was detected by real - time PCR, and the apoptosis rate of the HCM was tested by the flow cytometry. Results Our findings showed significant increase of MDA levels (P <0.05) and decrease of SOD activity(P<0.05) in the high glucose group compared with the control group. However,in the adiponectin group,MDA levels decreased (P<0.05) and SOD activity increased significantly (P <0.05) compared with those in the high - glucose group and they were time dependent. Compared with the control group,the expression of Ho-1 mRNA and P66Shc mRNA increased in the high -glucose group. The adiponectin group expressed a higher level of Ho - 1 mRNA but a lower level of P66Shc mRNA compared with the glucose group (P < 0.05) and they were time dependent. The apoptosis rate of the HCM in the high - glucose group was higher than the control group; while the apoptotic rate in the adiponectin group declined remarkably compared with the high glucose group. Conclusion The adiponectin has a protective effect on diabetes myocardial cells by upregulating the expression of Ho - 1 mRNA and downregulating the expression of P66Shc mRNA, which can

  20. Present Researching Approaches and Future Prospects for Treatment of Cardiac Diseases-Integrative Medicine

    Institute of Scientific and Technical Information of China (English)

    Yan Feng; Hao Xu; Yi-Xin Wang; Li-Ping Ma; Da-Zhuo Shi

    2015-01-01

    The pathogenesis of cardiac diseases is very complex and involved in many gene transcription and protein expression. How to effectively treat the diseases has become the hotspot of modern medicine. Accumulating evidences over the past decades on integrative medicine have shown us hopeful future prospects. With the development of modern biomedicine, such as sketch mapping genomic sequence, functional genomics, proteomics and pharmacogenetics, more advanced techniques could be applied in elucidating the possibly complicated biological networks, or complex pathological and physiological mechanisms underlying cardiac diseases, by which integrative medicine will also bring out some new and more effective strategies in the treatment of cardiac diseases.

  1. Stimulation of isolated ventricular myocytes within an open architecture microarray.

    Science.gov (United States)

    Klauke, Norbert; Smith, Godfrey L; Cooper, Jonathan M

    2005-03-01

    This paper is concerned with the physiological responses of single heart cells within microfluidic chambers, in response to stimulation by integrated microelectrodes. To enable these investigations, which included the measurement of action potential duration, intracellular Ca2+ and cell shortening, a series of microfluidic chambers (50 microm wide, 180 microm long, 400 microm high, 500 microm pitch) and connecting channels (200 microm wide, 5000 microm long, 50 microm high, 500 microm pitch) were replica-moulded into the silicone elastomer, polydimethylsiloxane (PDMS). The structures were formed against a master of posts and lines, photolithograhically patterned into the high aspect ratio photoresist SU-8. The chambers within the slab of PDMS were aligned against pairs of stimulating gold microelectrodes (50 microm long, 20 microm wide, 0.1-10 microm thick, 180 microm apart) patterned on a microscope coverslip base, thus defining cavities of approximately 4 nL volume. The assembly was filled with physiological saline and single isolated rabbit ventricular myocytes were introduced by micropipetting, thus creating limited volumes of saline above individual myocytes that could be varied between 4 nL and > or = 4 microL. The application of transient current pulses to the cells via the electrodes caused transient contractions with constant amplitude (recorded as changes in sarcomere length), confirming that excitation contraction coupling (EC coupling) remained functional in these limited volumes. Continuous monitoring of the intracellular Ca2+ (using calcium sensitive dyes) showed, that in the absence of bath perfusion, the amplitude of the transients remained constant for approximately 3 min in the 4-nL volume and approximately 20 min for the 4 microL volume. Beyond this time, the cells became unexcitable until the bath was renewed. The action potential duration (APD) was recorded at stimulation frequencies of 1 Hz and 0.5 Hz using potential sensitive dyes and was

  2. An integrated platform for image-guided cardiac resynchronization therapy

    Science.gov (United States)

    Ma, Ying Liang; Shetty, Anoop K.; Duckett, Simon; Etyngier, Patrick; Gijsbers, Geert; Bullens, Roland; Schaeffter, Tobias; Razavi, Reza; Rinaldi, Christopher A.; Rhode, Kawal S.

    2012-05-01

    Cardiac resynchronization therapy (CRT) is an effective procedure for patients with heart failure but 30% of patients do not respond. This may be due to sub-optimal placement of the left ventricular (LV) lead. It is hypothesized that the use of cardiac anatomy, myocardial scar distribution and dyssynchrony information, derived from cardiac magnetic resonance imaging (MRI), may improve outcome by guiding the physician for optimal LV lead positioning. Whole heart MR data can be processed to yield detailed anatomical models including the coronary veins. Cine MR data can be used to measure the motion of the LV to determine which regions are late-activating. Finally, delayed Gadolinium enhancement imaging can be used to detect regions of scarring. This paper presents a complete platform for the guidance of CRT using pre-procedural MR data combined with live x-ray fluoroscopy. The platform was used for 21 patients undergoing CRT in a standard catheterization laboratory. The patients underwent cardiac MRI prior to their procedure. For each patient, a MRI-derived cardiac model, showing the LV lead targets, was registered to x-ray fluoroscopy using multiple views of a catheter looped in the right atrium. Registration was maintained throughout the procedure by a combination of C-arm/x-ray table tracking and respiratory motion compensation. Validation of the registration between the three-dimensional (3D) roadmap and the 2D x-ray images was performed using balloon occlusion coronary venograms. A 2D registration error of 1.2 ± 0.7 mm was achieved. In addition, a novel navigation technique was developed, called Cardiac Unfold, where an entire cardiac chamber is unfolded from 3D to 2D along with all relevant anatomical and functional information and coupled to real-time device detection. This allowed more intuitive navigation as the entire 3D scene was displayed simultaneously on a 2D plot. The accuracy of the unfold navigation was assessed off-line using 13 patient data sets

  3. Mechanical analysis of single myocyte contraction in a 3-D elastic matrix.

    Directory of Open Access Journals (Sweden)

    John Shaw

    Full Text Available BACKGROUND: Cardiac myocytes experience mechanical stress during each heartbeat. Excessive mechanical stresses under pathological conditions cause functional and structural remodeling that lead to heart diseases, yet the precise mechanisms are still incompletely understood. To study the cellular and molecular level mechanotransduction mechanisms, we developed a new 'cell-in-gel' experimental system to exert multiaxial (3-D stresses on a single myocyte during active contraction. METHODS: Isolated myocytes are embedded in an elastic hydrogel to simulate the mechanical environment in myocardium (afterload. When electrically stimulated, the in-gel myocyte contracts while the matrix resists shortening and broadening of the cell, exerting normal and shear stresses on the cell. Here we provide a mechanical analysis, based on the Eshelby inclusion problem, of the 3-D strain and stress inside and outside the single myocyte during contraction in an elastic matrix. RESULTS: (1 The fractional shortening of the myocyte depends on the cell's geometric dimensions and the relative stiffness of the cell to the gel. A slender or softer cell has less fractional shortening. A myocyte of typical dimensions embedded in a gel of similar elastic stiffness can contract only 20% of its load-free value. (2 The longitudinal stress inside the cell is about 15 times the transverse stress level. (3 The traction on the cell surface is highly non-uniform, with a maximum near its ends, showing 'hot spots' at the location of intercalated disks. (4 The mechanical energy expenditure of the myocyte increases with the matrix stiffness in a monotonic and nonlinear manner. CONCLUSION: Our mechanical analyses provide analytic solutions that readily lend themselves to parametric studies. The resulting 3-D mapping of the strain and stress states serve to analyze and interpret ongoing cell-in-gel experiments, and the mathematical model provides an essential tool to decipher and quantify

  4. Modes of induced cardiac arrest: hyperkalemia and hypocalcemia--literature review.

    Science.gov (United States)

    Oliveira, Marcos Aurélio Barboza de; Brandi, Antônio Carlos; Santos, Carlos Alberto dos; Botelho, Paulo Henrique Husseini; Cortez, José Luis Lasso; Braile, Domingo Marcolino

    2014-01-01

    The entry of sodium and calcium play a key effect on myocyte subjected to cardiac arrest by hyperkalemia. They cause cell swelling, acidosis, consumption of adenosine triphosphate and trigger programmed cell death. Cardiac arrest caused by hypocalcemia maintains intracellular adenosine triphosphate levels, improves diastolic performance and reduces oxygen consumption, which can be translated into better protection to myocyte injury induced by cardiac arrest.

  5. On-chip acidification rate measurements from single cardiac cells confined in sub-nanoliter volumes

    OpenAIRE

    Ges, Igor A.; Dzhura, Igor A.; Baudenbacher, Franz J.

    2008-01-01

    The metabolic activity of cells can be monitored by measuring the pH in the extracellular environment. Microfabrication and microfluidic technologies allow the sensor size and the extracellular volumes to be comparable to single cells. A glass substrate with thin film pH sensitive IrOx electrodes was sealed to a replica-molded polydimethylsiloxane (PDMS) microfluidic network with integrated valves. The device, termed NanoPhysiometer, allows the trapping of single cardiac myocytes and the meas...

  6. Oxidative stress decreases microtubule growth and stability in ventricular myocytes.

    Science.gov (United States)

    Drum, Benjamin M L; Yuan, Can; Li, Lei; Liu, Qinghang; Wordeman, Linda; Santana, L Fernando

    2016-04-01

    Microtubules (MTs) have many roles in ventricular myocytes, including structural stability, morphological integrity, and protein trafficking. However, despite their functional importance, dynamic MTs had never been visualized in living adult myocytes. Using adeno-associated viral vectors expressing the MT-associated protein plus end binding protein 3 (EB3) tagged with EGFP, we were able to perform live imaging and thus capture and quantify MT dynamics in ventricular myocytes in real time under physiological conditions. Super-resolution nanoscopy revealed that EB1 associated in puncta along the length of MTs in ventricular myocytes. The vast (~80%) majority of MTs grew perpendicular to T-tubules at a rate of 0.06μm∗s(-1) and growth was preferentially (82%) confined to a single sarcomere. Microtubule catastrophe rate was lower near the Z-line than M-line. Hydrogen peroxide increased the rate of catastrophe of MTs ~7-fold, suggesting that oxidative stress destabilizes these structures in ventricular myocytes. We also quantified MT dynamics after myocardial infarction (MI), a pathological condition associated with increased production of reactive oxygen species (ROS). Our data indicate that the catastrophe rate of MTs increases following MI. This contributed to decreased transient outward K(+) currents by decreasing the surface expression of Kv4.2 and Kv4.3 channels after MI. On the basis of these data, we conclude that, under physiological conditions, MT growth is directionally biased and that increased ROS production during MI disrupts MT dynamics, decreasing K(+) channel trafficking.

  7. Biosynthesis of cardiac natriuretic peptides

    DEFF Research Database (Denmark)

    Goetze, Jens Peter

    2010-01-01

    . An inefficient post-translational prohormone maturation will also affect the biology of the cardiac natriuretic peptide system. This review aims at summarizing the myocardial synthesis of natriuretic peptides focusing on B-type natriuretic peptide, where new data has disclosed cardiac myocytes as highly...

  8. Molecular Aspects of Exercise-induced Cardiac Remodeling.

    Science.gov (United States)

    Bernardo, Bianca C; McMullen, Julie R

    2016-11-01

    Exercise-induced cardiac remodeling is typically an adaptive response associated with cardiac myocyte hypertrophy and renewal, increased cardiac myocyte contractility, sarcomeric remodeling, cell survival, metabolic and mitochondrial adaptations, electrical remodeling, and angiogenesis. Initiating stimuli/triggers of cardiac remodeling include increased hemodynamic load, increased sympathetic activity, and the release of hormones and growth factors. Prolonged and strenuous exercise may lead to maladaptive exercise-induced cardiac remodeling including cardiac dysfunction and arrhythmia. In addition, this article describes novel therapeutic approaches for the treatment of heart failure that target mechanisms responsible for adaptive exercise-induced cardiac remodeling, which are being developed and tested in preclinical models.

  9. Effects of 17-methoxyl-7-hydroxy-benzfuranchalcon on Intracellular Calcium Overload in Cultured Cardiac Myocytes of Neonatal Rats Injured by H2O2 and L-type Calcium Current in Isolated Ventricular Myocytes of Mice%17-甲氧基-7-羟基-苯并呋喃查尔酮对心肌细胞内游离钙浓度及L-型钙电流的影响

    Institute of Scientific and Technical Information of China (English)

    李映新; 黄媛恒; 覃斐章; 林兴; 黄仁彬

    2013-01-01

    Objective:To investigate the effects of 17-methoxyl-7-hydroxy-benzfuranchalcon (YLSC) on intracellular calcium overload in cultured cardiac myocytes of neonatal rats injured by H2O2 and L-type calcium current (ICa-L) in isolated ventricular myocytes.Method:The cells of primary cultured cardiac myocytes of neonatal rats were divided into groups:①control group; ② model group:administrated with 0.3 mmol · L-1 H2O2; ③YLSC treated groups:incubation respectively with 100,200,400 μmol ·L-1 YLSC for 24 h,and add 0.3 mmol · L-1 H2O2.Laser confocal microscopy was used with Fluo-3/Am as indicator to detect changes of [Ca2+]i immediately and 15 mintues after H2O2 intervention.Single ventricular cell was obtained enzymatically by Langendorff perfusion apparatus.The wholecell patch clamp was used to record the ICa-L.Result:①The average fluorescence intensity values of the model group treated by H2O2 higher significantly than control group and the fluorescence enhancement ratio was 60.43 % ± 7.75%.The YLSC could decline the intensity values in a does-dependent manner manner,the fluorescence enhancement ratios of low,middle and high does respectively were 38.39% ±13.87%,14.49% ±2.94%,-28.1% ± 1.52%,and all of them were much lower compared with H2O2 group (P < 0.01).②YLSC can up-shifted the current-voltage (Ⅰ-Ⅴ) curves and markedly shifted the steady state activation and inactivation curve of ICa-L to the left.Conclusion:YLSC inhibited the L-type calcium channel,it can significantly reduce the myocardial intracellular Ca2+ overload induced by H2O2.%目的:研究17-甲氧基-7-羟基-苯并呋喃查尔酮(YLSC)对H2O2诱导的心肌细胞内钙超载的拮抗作用及对L型钙电流(ICa-L)的影响.方法:采用SD大鼠乳鼠进行心肌细胞培养,实验分为①正常对照组;②H2O2组:上机前加入终浓度为0.3 mmol·L-1的H2O2;③预先给予低、中、高不同终浓度YLSC药物处理组:分别给予100,200,400 μmol·L-1YLSC

  10. Identification of caveolar resident proteins in ventricular myocytes using a quantitative proteomic approach: dynamic changes in caveolar composition following adrenoceptor activation.

    Science.gov (United States)

    Wypijewski, Krzysztof J; Tinti, Michele; Chen, Wenzhang; Lamont, Douglas; Ashford, Michael L J; Calaghan, Sarah C; Fuller, William

    2015-03-01

    The lipid raft concept proposes that membrane environments enriched in cholesterol and sphingolipids cluster certain proteins and form platforms to integrate cell signaling. In cardiac muscle, caveolae concentrate signaling molecules and ion transporters, and play a vital role in adrenergic regulation of excitation-contraction coupling, and consequently cardiac contractility. Proteomic analysis of cardiac caveolae is hampered by the presence of contaminants that have sometimes, erroneously, been proposed to be resident in these domains. Here we present the first unbiased analysis of the proteome of cardiac caveolae, and investigate dynamic changes in their protein constituents following adrenoreceptor (AR) stimulation. Rat ventricular myocytes were treated with methyl-β-cyclodextrin (MβCD) to deplete cholesterol and disrupt caveolae. Buoyant caveolin-enriched microdomains (BCEMs) were prepared from MβCD-treated and control cell lysates using a standard discontinuous sucrose gradient. BCEMs were harvested, pelleted, and resolubilized, then alkylated, digested, and labeled with iTRAQ reagents, and proteins identified by LC-MS/MS on a LTQ Orbitrap Velos Pro. Proteins were defined as BCEM resident if they were consistently depleted from the BCEM fraction following MβCD treatment. Selective activation of α-, β1-, and β2-AR prior to preparation of BCEMs was achieved by application of agonist/antagonist pairs for 10 min in populations of field-stimulated myocytes. We typically identified 600-850 proteins per experiment, of which, 249 were defined as high-confidence BCEM residents. Functional annotation clustering indicates cardiac BCEMs are enriched in integrin signaling, guanine nucleotide binding, ion transport, and insulin signaling clusters. Proteins possessing a caveolin binding motif were poorly enriched in BCEMs, suggesting this is not the only mechanism that targets proteins to caveolae. With the notable exception of the cavin family, very few proteins show

  11. Integrating Care in Complex Cardiac Care: the Tech Touch

    OpenAIRE

    Stellato, Kira; Radini, Donatella; Pellizzari, Mara; Pordenon, Marta; Pletti, Luciano; Humar, Franco; Apuzzo, Matteo; Fragiacomo, Emanuela; Delli Quadri, Nicola; Di Lenarda, Andrea

    2016-01-01

    Background: The ageing of European population and the steady increasing of complex chronic disease pose substantial challenges to the sustainability of health and social care services and to the quality of life of European citizens . The testing of new frontiers of eCare for outpatient domiciliary monitoring of elderly citizens is essential in order to assess efficacy and sustainability of new technologies for integrated care, including telehealth and telemonitoring platforms. Friuli-Venezia ...

  12. Integrative Analysis of MicroRNA and mRNA Data Reveals an Orchestrated Function of MicroRNAs in Skeletal Myocyte Differentiation in Response to TNF-α or IGF1.

    Directory of Open Access Journals (Sweden)

    Swanhild U Meyer

    Full Text Available Skeletal muscle cell differentiation is impaired by elevated levels of the inflammatory cytokine tumor necrosis factor-α (TNF-α with pathological significance in chronic diseases or inherited muscle disorders. Insulin like growth factor-1 (IGF1 positively regulates muscle cell differentiation. Both, TNF-α and IGF1 affect gene and microRNA (miRNA expression in this process. However, computational prediction of miRNA-mRNA relations is challenged by false positives and targets which might be irrelevant in the respective cellular transcriptome context. Thus, this study is focused on functional information about miRNA affected target transcripts by integrating miRNA and mRNA expression profiling data.Murine skeletal myocytes PMI28 were differentiated for 24 hours with concomitant TNF-α or IGF1 treatment. Both, mRNA and miRNA expression profiling was performed. The data-driven integration of target prediction and paired mRNA/miRNA expression profiling data revealed that i the quantity of predicted miRNA-mRNA relations was reduced, ii miRNA targets with a function in cell cycle and axon guidance were enriched, iii differential regulation of anti-differentiation miR-155-5p and miR-29b-3p as well as pro-differentiation miR-335-3p, miR-335-5p, miR-322-3p, and miR-322-5p seemed to be of primary importance during skeletal myoblast differentiation compared to the other miRNAs, iv the abundance of targets and affected biological processes was miRNA specific, and v subsets of miRNAs may collectively regulate gene expression.Joint analysis of mRNA and miRNA profiling data increased the process-specificity and quality of predicted relations by statistically selecting miRNA-target interactions. Moreover, this study revealed miRNA-specific predominant biological implications in skeletal muscle cell differentiation and in response to TNF-α or IGF1 treatment. Furthermore, myoblast differentiation-associated miRNAs are suggested to collectively regulate gene

  13. Interplay between cardiac function and heart development.

    Science.gov (United States)

    Andrés-Delgado, Laura; Mercader, Nadia

    2016-07-01

    Mechanotransduction refers to the conversion of mechanical forces into biochemical or electrical signals that initiate structural and functional remodeling in cells and tissues. The heart is a kinetic organ whose form changes considerably during development and disease. This requires cardiomyocytes to be mechanically durable and able to mount coordinated responses to a variety of environmental signals on different time scales, including cardiac pressure loading and electrical and hemodynamic forces. During physiological growth, myocytes, endocardial and epicardial cells have to adaptively remodel to these mechanical forces. Here we review some of the recent advances in the understanding of how mechanical forces influence cardiac development, with a focus on fluid flow forces. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.

  14. Ionic Remodeling and Direct Effects of Valsartan on Ionic Currentsin Human Atrial Myocytes with Atrial Fibrillation

    Institute of Scientific and Technical Information of China (English)

    Xue Yumei; Wu Shulin; Deng Chunyu; Qian Weimin; Chen Chunbo

    2004-01-01

    Objectives Previous studies demonstrated that angiotensin receptor antagonists had effects on some potassium channels in guinea pig myocytes and cloned channels that expressed in human cardiac myocytes. This study determined the direct effects of Valsartan on I caL, INa, IKur, IK1 and Ito1 in isolated human atrial myocytes. Methods and Results Specimens of right atrial appendage tissue were obtained from 39 patients with coronary artery and valvular heart diseases during cardiopulmonary bypass procedure. Pre- operation cardiac rhythm was sinus (SR)in 19 patients and was atrial fibrillation (AF) in the others. Single atrial myocyte was isolated by enzymatic dissociation with the chunk method. The ionic currents were recorded using the whole cell coffiguration of the voltage clamp technique. ICaL and Ito1 densities in AF patients were significantly lower than those in SR patients by 74% and 60%, respectively, while IK1density was significantly higher by 34% at command potential of - 120 mV. With 10 μmol/L Valsartan, INa density was significantly decreased by 59% in SR patients and by 66% in AF patients. IKur and IKl density were significantly decreased in only AF patients by 31% and23%, respectively. Conclusions Conclusions Decreased IcaL and Itol and increased IKl at hyperpolarizing potentials in AF patients' atrial myocytes may result from the electrophysiological remodeling by AF. Valsartan significantly decreases INa, IK1 and IKur current densities in AF patients' myocyte, but decreases only INa in SR patients' myocyte, suggesting that Valsartan may be beneficial to the recovering of remolded atria.

  15. mAKAP – A Master Scaffold for Cardiac Remodeling

    Science.gov (United States)

    Passariello, Catherine L.; Li, Jinliang; Dodge-Kafka, Kimberly; Kapiloff, Michael S.

    2014-01-01

    Cardiac remodeling is regulated by an extensive intracellular signal transduction network. Each of the many signaling pathways in this network contributes uniquely to the control of cellular adaptation. In the last few years, it has become apparent that multimolecular signaling complexes or ‘signalosomes’ are important for fidelity in intracellular signaling and for mediating crosstalk between the different signaling pathways. These complexes integrate upstream signals and control downstream effectors. In the cardiac myocyte, the protein mAKAPβ serves as a scaffold for a large signalosome that is responsive to cAMP, calcium, hypoxia, and mitogen-activated protein kinase signaling. The main function of mAKAPβ signalosomes is to modulate stress-related gene expression regulated by the transcription factors NFATc, MEF2 and HIF-1α and type II histone deacetylases that control pathological cardiac hypertrophy. PMID:25551320

  16. Integration of trans-esophageal echocardiography with magnetic tracking technology for cardiac interventions

    Science.gov (United States)

    Moore, John T.; Wiles, Andrew D.; Wedlake, Chris; Bainbridge, Daniel; Kiaii, Bob; Trejos, Ana Luisa; Patel, Rajni; Peters, Terry M.

    2010-02-01

    Trans-esophageal echocardiography (TEE) is a standard component of patient monitoring during most cardiac surgeries. In recent years magnetic tracking systems (MTS) have become sufficiently robust to function effectively in appropriately structured operating room environments. The ability to track a conventional multiplanar 2D TEE transducer in 3D space offers incredible potential by greatly expanding the cumulative field of view of cardiac anatomy beyond the limited field of view provided by 2D and 3D TEE technology. However, there is currently no TEE probe manufactured with MTS technology embedded in the transducer, which means sensors must be attached to the outer surface of the TEE. This leads to potential safety issues for patients, as well as potential damage to the sensor during procedures. This paper presents a standard 2D TEE probe fully integrated with MTS technology. The system is evaluated in an environment free of magnetic and electromagnetic disturbances, as well as a clinical operating room in the presence of a da Vinci robotic system. Our first integrated TEE device is currently being used in animal studies for virtual reality-enhanced ultrasound guidance of intracardiac surgeries, while the "second generation" TEE is in use in a clinical operating room as part of a project to measure perioperative heart shift and optimal port placement for robotic cardiac surgery. We demonstrate excellent system accuracy for both applications.

  17. Non-pharmacological strategies to decrease anxiety in cardiac catheterization: integrative review

    Directory of Open Access Journals (Sweden)

    Natany da Costa Ferreira

    2015-12-01

    Full Text Available ABSTRACT Objective: to identify and review the literature on non-pharmacological strategies used for reducing anxiety in patients receiving cardiac catheterization. Method: this study was an integrative literature review. The research was conducted using the databases LILACS, SciELO, Medline (through BVS and PubMed and Scopus. Studies were analyzed according to their objective, method, instruments used for evaluating patients' anxiety, and the results obtained. Results: the most used strategy for reducing anxiety in patients receiving cardiac catheterization was music therapy. However, no study identifying the most appropriate time for this intervention (before, during and/or after the procedure was found. Other strategies identified in this review were educational videos, massage, and palm therapy. Conclusion: the results found suggest that anxiety can be reduced using non-pharmacological strategies.

  18. Stimulating endogenous cardiac regeneration

    Directory of Open Access Journals (Sweden)

    Amanda eFinan

    2015-09-01

    Full Text Available The healthy adult heart has a low turnover of cardiac myocytes. The renewal capacity, however, is augmented after cardiac injury. Participants in cardiac regeneration include cardiac myocytes themselves, cardiac progenitor cells, and peripheral stem cells, particularly from the bone marrow compartment. Cardiac progenitor cells and bone marrow stem cells are augmented after cardiac injury, migrate to the myocardium, and support regeneration. Depletion studies of these populations have demonstrated their necessary role in cardiac repair. However, the potential of these cells to completely regenerate the heart is limited. Efforts are now being focused on ways to augment these natural pathways to improve cardiac healing, primarily after ischemic injury but in other cardiac pathologies as well. Cell and gene therapy or pharmacological interventions are proposed mechanisms. Cell therapy has demonstrated modest results and has passed into clinical trials. However, the beneficial effects of cell therapy have primarily been their ability to produce paracrine effects on the cardiac tissue and recruit endogenous stem cell populations as opposed to direct cardiac regeneration. Gene therapy efforts have focused on prolonging or reactivating natural signaling pathways. Positive results have been demonstrated to activate the endogenous stem cell populations and are currently being tested in clinical trials. A potential new avenue may be to refine pharmacological treatments that are currently in place in the clinic. Evidence is mounting that drugs such as statins or beta blockers may alter endogenous stem cell activity. Understanding the effects of these drugs on stem cell repair while keeping in mind their primary function may strike a balance in myocardial healing. To maximize endogenous cardiac regeneration,a combination of these approaches couldameliorate the overall repair process to incorporate the participation ofmultiple cell players.

  19. Mechanical modulation of cardiac microtubules.

    Science.gov (United States)

    White, Ed

    2011-07-01

    Microtubules are a major component of the cardiac myocyte cytoskeleton. Interventions that alter it may influence cardiac mechanical and electrical activity by disrupting the trafficking of proteins to and from the surface membrane by molecular motors such as dynein, which use microtubules as tracks to step along. Free tubulin dimers may transfer GTP to the α-subunits of G-proteins, thus an increase in free tubulin could increase the activity of G-proteins; evidence for and against such a role exists. There is more general agreement that microtubules act as compression-resisting structures within myocytes, influencing visco-elasticity of myocytes and increasing resistance to shortening when proliferated and resisting deformation from longitudinal shear stress. In response to pressure overload, there can be post-translational modifications resulting in more stable microtubules and an increase in microtubule density. This is accompanied by contractile dysfunction of myocytes which can be reversed by microtubule disruption. There are reports of mechanically induced changes in electrical activity that are dependent upon microtubules, but at present, a consensus is lacking on whether disruption or proliferation would be beneficial in the prevention of arrhythmias. Microtubules certainly play a role in the response of cardiac myocytes to mechanical stimulation, the exact nature and significance of this role is still to be fully determined.

  20. Chronotropic Biosensing Via Stem-Cell Derived Myocyte Aggregates

    Science.gov (United States)

    2007-11-02

    the example of Figure 2, the myocyte aggregates showed a high degree of ab - solute tracking; for the 6 sustained-activity aggregates, the cor- relation...chronotropy. Indeed, excitable-cell biosensor systems could lead to the development of long-term, physiologically- tuned, functionally integrated bioprocessing ...H. Ko- dama, J. Pan, M. Sano, T. Takahashi, S. Hori, H. Abe , J. Hata, A. Umezawa, and S. Ogawa, “Cardiomyocytes can be generated from marrow stromal

  1. 辛伐他汀预处理在脓毒症大鼠心肌细胞NF-κB 表达中的意义%Significance of simvastatin pretreatment on NF-κB expression in cardiac myocytes of rats with sepsis

    Institute of Scientific and Technical Information of China (English)

    张立涛; 刘洪英; 许宁; 赵鹤龄

    2013-01-01

    目的:观察心肌细胞核转录因子-κB( NF-κB)在脓毒症大鼠心肌细胞的表达,并探讨辛伐他汀预处理对其表达的影响及意义。方法雌性Wistar大鼠60只随机分为3组:正常组,脓毒症组和辛伐他汀组,每组20例。处理方法:应用盲肠结扎穿孔法制造脓毒症模型。辛伐他汀组:辛伐他汀20 mg/kg喂养,每天1次,共2周。2周后辛伐他汀组与脓毒症组大鼠行盲肠结扎穿孔术。术后48 h取3组大鼠心肌组织制成石蜡切片,采用免疫组织化学染色的方法观察心肌细胞NF-κB的蛋白表达。结果免疫组织化学染色显示脓毒症组大鼠心肌细胞NF-κB蛋白表达较正常组明显增加( P <0抖.05),辛伐他汀组大鼠心肌细胞NF-κB 蛋白表达与脓毒症组相比明显减弱( P <0.05),与正常组相比差异有统计学意义( P <0.05)。结论辛伐他汀可以减弱脓毒症大鼠心肌细胞NF-κB的蛋白表达,改善脓毒症时的心脏功能。%Objce tive To investigate the expression of NF-κB in cardiac myocytes of rats with sepsis and to explore the effects of simvastatin pretreatment on expression of NF-κB and its significance .Methods Sixty female Wistar rats were randomly divided into three groups:control group ,sepsis group and simvastatin group ,with 20 rats in each group.The animal models with sepsis were established by cecal ligation and puncture (CLP).The rats in simvastatin group were treated with simvastatin ,20mg/kg,once a day for two weeks before CLP .After two weeks the rats in simvastatin group and sepsis group received CLP .The cardiac tissues of the three groups were collected 48h after CLP, and all the specimens were made into paraffin sections , then the expression levels of NF-κB were detected by immunohistochemistry staining .Resutl s Immunohistochemistry staining showed that the expression levels of NF-κB in sepsis group were significantly higher than those in

  2. PERK signal pathway is involved in hypoxia-induced endoplasmic reti culum stress and apoptosis in cultured cardiac myocytes%PERK通路参与了缺氧心肌细胞的内质网应激及凋亡

    Institute of Scientific and Technical Information of China (English)

    刘春蕾; 李鑫; 李蕊君; 何云云; 何昆仑; 王莉莉

    2012-01-01

    AIM: To invesligale the role of endoplasmic reliculum (ER) slress in the process of hypoxia — induced neonalal ral myocardial injury through PERK signal pathway. METHODS: Neonalal rat cardiac myocyles were randomly divided into conlrol group and hypoxia 1 h, 4 h, 8 h, 12 h and 24 h groups. Cell viability was evaluated by delermi-ning the inlracellular conlenl of ATP. Apoptosis was measured by high — conlenl analysis ( HCA) cell imaging syslem. The prolein levels of GRP78, calreliculin, p — PERK, p — eIF2α, ATF4 and CHOP were delecled by Weslern blolling at differ-ent Lime poinls. The primary cullured neonalal ral cardiac myocyles were Irealed with an agonisl of PERK palhway salu-brinal and the cell apoplosis was observed under hypoxia. RESULTS: In the early phase, hypoxia induced an increase in the expression of calreliculin and GPR78. In the middle phase of hypoxia, the levels of p — PERK, p — eIF2α and ATF4 were increased. In the later phase of hypoxia, increased CHOP level was also observed. Salubrinal effectively prolecled the cardiac myocyles from hypoxic injury. CONCLUSION: Hypoxia aclivales ER slress in cardiac myocyles and also aclivales PERK signal palhway. PERK signaling prolecls cardiac myocyles from hypoxic damage in the early stage and triggers apoplosis of the cells in the laler phase.%目的:观察缺氧对原代培养的Wistar乳鼠心肌细胞的损伤,探讨内质网应激在缺氧心肌损伤发生发展过程中起的作用及PERK通路是否参与其信号转导过程.方法:将原代培养的乳鼠心肌细胞随机分为正常对照组和缺氧1 h、4 h、8 h、12 h、24 h组,通过测定细胞ATP含量反映细胞活力;高内涵分析细胞成像系统检测多参数凋亡;采用免疫细胞化学和蛋白印迹方法检测以内质网为靶点的分子伴侣(GRP78和钙网蛋白)的表达,PERK通路(PERK和eIF2α)的磷酸化水平,以及其下游分子(ATF4和CHOP)在缺氧不同时点蛋白的表达变化特征.采用PERK

  3. 1a,25(OH)2 D3对心肌细胞生物钟基因表达的影响%Effect of 1a,25(OH)2 D3 on circadian clock gene expression in cardiac myocytes

    Institute of Scientific and Technical Information of China (English)

    陈玉梅; 范邁; 李杏; 李华; 吴丽洁; 张奇军; 程子杰; 钱玲梅

    2016-01-01

    目的:探讨1a,25(OH)2 D3对心肌细胞生物钟基因 Bmal1 mRNA、Per2 mRNA 和 Rev-erba mRNA表达的影响。方法分离培养7日龄 SD 大鼠乳鼠心肌细胞,并用免疫荧光法鉴定。原代心肌细胞培养72 h后,设置1a,25(OH)2 D35个终浓度梯度即0 nmol/L、1 nmol/L、10 nmol/L、50 nmol/L 和100 nmol/L 处理心肌细胞2 h,然后提取细胞 RNA,实时荧光定量 PCR(RT-PCR)检测生物钟基因(Bmal1、Per2、Rev-erba)表达量变化,以确定1a,25(OH)2 D3最佳处理浓度。再将培养72 h 的原代心肌细胞分为3组,对照组:无血清培养基培养;血清休克组:含体积分数50%马血清的 DMEM培养2 h;1a,25(OH)2 D3处理组:最佳1a,25(OH)2 D3浓度培养2 h。分别于7个时间点(0 h、4 h、8 h、12 h、16 h、20 h、24 h)收集细胞,提取细胞总 RNA,再采用 RT-PCR 分析心肌细胞生物钟基因(Bmal1,Per2,Rev-erba)的转录水平。结果1a,25(OH)2 D3培养浓度为50 nmol/L 时, Bmal1 mRNA 表达水平最高,Per2和 Rev-erba mRNA 表达水平最低。与对照组相比,1a,25(OH)2 D3处理组和血清休克组均引起心肌细胞 Bmal1、Per2和 Rev-erba 基因呈日周期的节律振荡,且 Bmal1和 Per2的表达模式呈相反的时相表达,在12 h 时 Bmal1的表达量出现在波峰,而 Per2的表达量出现在波谷。Rev-erba 的表达变化趋势在8 h 开始上升,在12~16 h 出现最高表达量。结论1a,25(OH)2 D3可影响心肌细胞生物钟基因 Bmal1、Per2和 Rev-erba mRNA 表达。%Objective To explore the effect of 1a,25(OH)2 D3 on circadian clock gene expressions in cardiac myocytes.Methods Cultured cardiac myocytes isolated from 7 -day -old Sprague -Dawley(SD)rats were identified by immunofluorescence.The medium including 1a,25 (OH)2 D3 (final concentrations were 0 nmol/L,1 nmol/L, 10 nmol/L,50 nmol/L and 100 nmol/L)were added to primary myocardial cells to

  4. Direct differentiation of atrial and ventricular myocytes from human embryonic stem cells by alternating retinoid signals

    Institute of Scientific and Technical Information of China (English)

    Qiangzhe Zhang; Li Chen; Tian Tian; Xin Wang; Pu Li; Jurgen Hescheler; Guangju Ji; Yue Ma; Junjie Jiang; Pengcheng Han; Qi Yuan; Jing Zhang; Xiaoqian Zhang; Yanyan Xu; Henghua Cao; Qingzhang Meng

    2011-01-01

    Although myocyte cell transplantation studies have suggested a promising therapeutic potential for myocardial infarction, a major obstacle to the development of clinical therapies for myocardial repair is the difficulties associated with obtaining relatively homogeneous ventricular myocytes for transplantation. Human embryonic stem cells (hESCs)are a promising source of cardiomyocytes. Here we report that retinoid signaling regulates the fate specification of atrial versus ventricular myocytes during cardiac differentiation of hESCs. We found that both Noggin and the panretinoic acid receptor antagonist BMS-189453 (RAi) significantly increased the cardiac differentiation efficiency of hESCs. To investigate retinoid functions, we compared Noggin+RAi-treated cultures with Noggin+RA-treated cultures. Our results showed that the expression levels of the ventricular-specific gene IRX-4 were radically elevated in Noggin+RAi-treated cultures. MLC-2V, another ventricular-specific marker, was expressed in the majority of the cardiomyocytes in Noggin+RAi-treated cultures, hut not in the cardiomyocytes of Noggin+RA-treated cultures. Flow cytometry analysis and electrophysiologicai studies indicated that with 64.7 ± 0.88% (mean ± s.e.m) cardiac differentiation efficiency, 83% of the cardiomyocytes in Noggin+RAi-treated cultures had embryonic ventricular-like action potentials (APs). With 50.7 ± 1.76% cardiac differentiation efficiency, 94% of the cardiomyocytes in Noggin+RA-treated cultures had embryonic atrial-like APs. These results were further confirmed by imaging studies that assessed the patterns and properties of the Ca2+ sparks of the cardiomyocytes from the two cultures. These findings demonstrate that retinoid signaling specifies the atrial versus ventricular differentiation of hESCs. This study also shows that relatively homogeneous embryonic atrial- and ventricular-like myocyte populations can be efficiently derived from hESCs by specifically regulating Noggin

  5. Effect of Transmurally Heterogeneous Myocyte Excitation-Contraction Coupling on Left Ventricular Electromechanics

    OpenAIRE

    2009-01-01

    The excitation-contraction coupling properties of cardiac myocytes isolated from different regions of the mammalian left ventricular wall have been shown to vary considerably, with uncertain effects on ventricular function. We embedded a cell-level excitation-contraction coupling model with region-dependent parameters within a simple finite element model of left ventricular geometry to study effects of electromechanical heterogeneity on local myocardial mechanics and global hemodynamics. This...

  6. Mouse atrial tumor myocytes AT-1 in cardiac electrophysiologic and pharmacologic studies%小鼠心房肌瘤AT-1细胞在心脏电生理学和药理学研究中的应用

    Institute of Scientific and Technical Information of China (English)

    杨韬

    2001-01-01

    Atrial tumor myocytes (AT-1 cells) were derived from tumor-bearing mice in which SV40 T large antigen drives atrial natriuretic promoter. AT-1 cells possess many features typically seen in cardiac cells from other species, such as spontaneous beating, multiple ion channels and responses to drugs, etc. Major ion channels are present in AT-1 cells: sodium, calcium and potassium channels. Sodium channel in AT-1 cells is highly sensitive to blocker tetrodotoxin. L- and T-type calcium channels respond to classical blockers. An important outward potassium current in AT-1 cells is the rapidly-activating delayed rectifier (IKr). IKr Is the sole time-dependently repolarizing potassium current in AT-1 cells. AT-1 cells are a very useful tool for studies in cardiac electrophysiology and pharmacology. As yet, a great number of cardiac and non-cardiac drugs have been tested for their IKr blocking actions in AT-1 cells. The polymorphic ventricular arrhythmia (torsade de pointes) is a severe side effect of IKr blockers.%小鼠心房肌瘤细胞(AT-1)系从转基因小鼠体内分化出来的一种心肌样细胞. AT-1细胞具有许多其他动物心脏细胞的典型特征,例如自发性搏动,多种离子通道和对许多药物起反应等. AT-1细胞上的主要离子通道包括钠,钙和钾通道. 钠通道对阻滞剂河豚毒高度敏感. L型和T型钙通道对典型的阻滞剂起反应. AT-1细胞上的一种重要外向钾电流是快速激活型迟缓整流外向钾电流(IKr). IKr是AT-1细胞上主要的时间依赖性复极化钾电流. 研究证明,AT-1细胞可作为心脏电生理学和药理学研究中的一种非常有用的工具. 迄今为止,在AT-1细胞上已经测试了许多心脏作用和非心脏作用药物的IKr阻滞作用. IKr阻滞药的一种严重副作用是可引起致死性的尖端扭转型室性心动过速.

  7. Multiphysics and multiscale modelling, data–model fusion and integration of organ physiology in the clinic: ventricular cardiac mechanics

    Science.gov (United States)

    Chabiniok, Radomir; Wang, Vicky Y.; Hadjicharalambous, Myrianthi; Asner, Liya; Lee, Jack; Sermesant, Maxime; Kuhl, Ellen; Young, Alistair A.; Moireau, Philippe; Nash, Martyn P.; Chapelle, Dominique

    2016-01-01

    With heart and cardiovascular diseases continually challenging healthcare systems worldwide, translating basic research on cardiac (patho)physiology into clinical care is essential. Exacerbating this already extensive challenge is the complexity of the heart, relying on its hierarchical structure and function to maintain cardiovascular flow. Computational modelling has been proposed and actively pursued as a tool for accelerating research and translation. Allowing exploration of the relationships between physics, multiscale mechanisms and function, computational modelling provides a platform for improving our understanding of the heart. Further integration of experimental and clinical data through data assimilation and parameter estimation techniques is bringing computational models closer to use in routine clinical practice. This article reviews developments in computational cardiac modelling and how their integration with medical imaging data is providing new pathways for translational cardiac modelling. PMID:27051509

  8. Fetal myocardium in the kidney capsule: an in vivo model of repopulation of myocytes by bone marrow cells.

    Directory of Open Access Journals (Sweden)

    Eric Y Zhang

    Full Text Available Debate surrounds the question of whether the heart is a post-mitotic organ in part due to the lack of an in vivo model in which myocytes are able to actively regenerate. The current study describes the first such mouse model--a fetal myocardial environment grafted into the adult kidney capsule. Here it is used to test whether cells descended from bone marrow can regenerate cardiac myocytes. One week after receiving the fetal heart grafts, recipients were lethally irradiated and transplanted with marrow from green fluorescent protein (GFP-expressing C57Bl/6J (B6 donors using normal B6 recipients and fetal donors. Levels of myocyte regeneration from GFP marrow within both fetal myocardium and adult hearts of recipients were evaluated histologically. Fetal myocardium transplants had rich neovascularization and beat regularly after 2 weeks, continuing at checkpoints of 1, 2, 4, 6, 8 and12 months after transplantation. At each time point, GFP-expressing rod-shaped myocytes were found in the fetal myocardium, but only a few were found in the adult hearts. The average count of repopulated myocardium with green rod-shaped myocytes was 996.8 cells per gram of fetal myocardial tissue, and 28.7 cells per adult heart tissue, representing a thirty-five fold increase in fetal myocardium compared to the adult heart at 12 months (when numbers of green rod-shaped myocytes were normalized to per gram of myocardial tissue. Thus, bone marrow cells can differentiate to myocytes in the fetal myocardial environment. The novel in vivo model of fetal myocardium in the kidney capsule appears to be valuable for testing repopulating abilities of potential cardiac progenitors.

  9. Myocyte repolarization modulates myocardial function in aging dogs.

    Science.gov (United States)

    Sorrentino, Andrea; Signore, Sergio; Qanud, Khaled; Borghetti, Giulia; Meo, Marianna; Cannata, Antonio; Zhou, Yu; Wybieralska, Ewa; Luciani, Marco; Kannappan, Ramaswamy; Zhang, Eric; Matsuda, Alex; Webster, Andrew; Cimini, Maria; Kertowidjojo, Elizabeth; D'Alessandro, David A; Wunimenghe, Oriyanhan; Michler, Robert E; Royer, Christopher; Goichberg, Polina; Leri, Annarosa; Barrett, Edward G; Anversa, Piero; Hintze, Thomas H; Rota, Marcello

    2016-04-01

    Studies of myocardial aging are complex and the mechanisms involved in the deterioration of ventricular performance and decreased functional reserve of the old heart remain to be properly defined. We have studied a colony of beagle dogs from 3 to 14 yr of age kept under a highly regulated environment to define the effects of aging on the myocardium. Ventricular, myocardial, and myocyte function, together with anatomical and structural properties of the organ and cardiomyocytes, were evaluated. Ventricular hypertrophy was not observed with aging and the structural composition of the myocardium was modestly affected. Alterations in the myocyte compartment were identified in aged dogs, and these factors negatively interfere with the contractile reserve typical of the young heart. The duration of the action potential is prolonged in old cardiomyocytes contributing to the slower electrical recovery of the myocardium. Also, the remodeled repolarization of cardiomyocytes with aging provides inotropic support to the senescent muscle but compromises its contractile reserve, rendering the old heart ineffective under conditions of high hemodynamic demand. The defects in the electrical and mechanical properties of cardiomyocytes with aging suggest that this cell population is an important determinant of the cardiac senescent phenotype. Collectively, the delayed electrical repolarization of aging cardiomyocytes may be viewed as a critical variable of the aging myopathy and its propensity to evolve into ventricular decompensation under stressful conditions.

  10. Testing a Longitudinal Integrated Self-Efficacy and Self-Determination Theory Model for Physical Activity Post-Cardiac Rehabilitation.

    Science.gov (United States)

    Sweet, Shane N; Fortier, Michelle S; Strachan, Shaelyn M; Blanchard, Chris M; Boulay, Pierre

    2014-01-13

    Self-determination theory and self-efficacy theory are prominent theories in the physical activity literature, and studies have begun integrating their concepts. Sweet, Fortier, Strachan and Blanchard (2012) have integrated these two theories in a cross-sectional study. Therefore, this study sought to test a longitudinal integrated model to predict physical activity at the end of a 4-month cardiac rehabilitation program based on theory, research and Sweet et al.'s cross-sectional model. Participants from two cardiac rehabilitation programs (N=109) answered validated self-report questionnaires at baseline, two and four months. Data were analyzed using Amos to assess the path analysis and model fit. Prior to integration, perceived competence and self-efficacy were combined, and labeled as confidence. After controlling for 2-month physical activity and cardiac rehabilitation site, no motivational variables significantly predicted residual change in 4-month physical activity. Although confidence at two months did not predict residual change in 4-month physical activity, it had a strong positive relationship with 2-month physical activity (β=0.30, Pself-efficacy theory were still partially supported. Because the model had good fit, this study demonstrated that theoretical integration is feasible.

  11. Testing a longitudinal integrated self-efficacy and self-determination theory model for physical activity post-cardiac rehabilitation

    Directory of Open Access Journals (Sweden)

    Shane N. Sweet

    2014-01-01

    Full Text Available Self-determination theory and self-efficacy theory are prominent theories in the physical activity literature, and studies have begun integrating their concepts. Sweet, Fortier, Strachan and Blanchard (2012 have integrated these two theories in a cross-sectional study. Therefore, this study sought to test a longitudinal integrated model to predict physical activity at the end of a 4-month cardiac rehabilitation program based on theory, research and Sweet et al.’s cross-sectional model. Participants from two cardiac rehabilitation programs (N=109 answered validated self-report questionnaires at baseline, two and four months. Data were analyzed using Amos to assess the path analysis and model fit. Prior to integration, perceived competence and self-efficacy were combined, and labeled as confidence. After controlling for 2-month physical activity and cardiac rehabilitation site, no motivational variables significantly predicted residual change in 4-month physical activity. Although confidence at two months did not predict residual change in 4-month physical activity, it had a strong positive relationship with 2-month physical activity (β=0.30, P<0.001. The overall model retained good fit indices. In conclusion, results diverged from theoretical predictions of physical activity, but self-determination and self-efficacy theory were still partially supported. Because the model had good fit, this study demonstrated that theoretical integration is feasible.

  12. Simulation of the effect of rogue ryanodine receptors on a calcium wave in ventricular myocytes with heart failure

    Science.gov (United States)

    Lu, Luyao; Xia, Ling; Ye, Xuesong; Cheng, Heping

    2010-06-01

    Calcium homeostasis is considered to be one of the most important factors for the contraction and relaxation of the heart muscle. However, under some pathological conditions, such as heart failure (HF), calcium homeostasis is disordered, and spontaneous waves may occur. In this study, we developed a mathematical model of formation and propagation of a calcium wave based upon a governing system of diffusion-reaction equations presented by Izu et al (2001 Biophys. J. 80 103-20) and integrated non-clustered or 'rogue' ryanodine receptors (rogue RyRs) into a two-dimensional (2D) model of ventricular myocytes isolated from failing hearts in which sarcoplasmic reticulum (SR) Ca2+ pools are partially unloaded. The model was then used to simulate the effect of rogue RyRs on initiation and propagation of the calcium wave in ventricular myocytes with HF. Our simulation results show that rogue RyRs can amplify the diastolic SR Ca2+ leak in the form of Ca2+ quarks, increase the probability of occurrence of spontaneous Ca2+ waves even with smaller SR Ca2+ stores, accelerate Ca2+ wave propagation, and hence lead to delayed afterdepolarizations (DADs) and cardiac arrhythmia in the diseased heart. This investigation suggests that incorporating rogue RyRs in the Ca2+ wave model under HF conditions provides a new view of Ca2+ dynamics that could not be mimicked by adjusting traditional parameters involved in Ca2+ release units and other ion channels, and contributes to understanding the underlying mechanism of HF.

  13. RSK3 – A Regulator of Pathological Cardiac Remodeling

    Science.gov (United States)

    Martinez, Eliana C.; Passariello, Catherine L.; Li, Jinliang; Matheson, Christopher J.; Dodge-Kafka, Kimberly; Reigan, Philip; Kapiloff, Michael S.

    2015-01-01

    Summary The family of p90 ribosomal S6 kinases (RSK) are pleiotropic effectors for extracellular signal-regulated kinase (ERK) signaling pathways. Recently, RSK3 was shown to be important for pathological remodeling of the heart. While cardiac myocyte hypertrophy can be compensatory for increased wall stress, in chronic heart diseases this non-mitotic cell growth is usually associated with interstitial fibrosis, increased cell death, and decreased cardiac function. Although RSK3 is less abundant in the cardiac myocyte than other RSK family members, RSK3 appears to serve a unique role in cardiac myocyte stress responses. A potential mechanism conferring RSK3’s unique function in the heart is anchoring by the scaffold protein muscle A-kinase Anchoring Protein β (mAKAPβ). Recent findings suggest that RSK3 should be considered as a therapeutic target for the prevention of heart failure, a clinical syndrome of major public health significance. PMID:25988524

  14. Real-time QRS detection using integrated variance for ECG gated cardiac MRI

    Directory of Open Access Journals (Sweden)

    Schmidt Marcus

    2016-09-01

    Full Text Available During magnetic resonance imaging (MRI, a patient’s vital signs are required for different purposes. In cardiac MRI (CMR, an electrocardiogram (ECG of the patient is required for triggering the image acquisition process. However, a reliable QRS detection of an ECG signal acquired inside an MRI scanner is a challenging task due to the magnetohydrodynamic (MHD effect which interferes with the ECG. The aim of this work was to develop a reliable QRS detector usable inside the MRI which also fulfills the standards for medical devices (IEC 60601-2-27. Therefore, a novel real-time QRS detector based on integrated variance measurements is presented. The algorithm was trained on ANSI/AAMI EC13 test waveforms and was then applied to two databases with 12-lead ECG signals recorded inside and outside an MRI scanner. Reliable results for both databases were achieved for the ECG signals recorded inside (DBMRI: sensitivity Se = 99.94%, positive predictive value +P = 99.84% and outside (DBInCarT: Se = 99.29%, +P = 99.72% the MRI. Due to the accurate R-peak detection in real-time this can be used for monitoring and triggering in MRI exams.

  15. Calcium handling by vascular myocytes in hypertension

    Directory of Open Access Journals (Sweden)

    R.C.A. Tostes

    1997-03-01

    Full Text Available Calcium ions (Ca2+ trigger the contraction of vascular myocytes and the level of free intracellular Ca2+ within the myocyte is precisely regulated by sequestration and extrusion mechanisms. Extensive evidence indicates that a defect in the regulation of intracellular Ca2+ plays a role in the augmented vascular reactivity characteristic of clinical and experimental hypertension. For example, arteries from spontaneously hypertensive rats (SHR have an increased contractile sensitivity to extracellular Ca2+ and intracellular Ca2+ levels are elevated in aortic smooth muscle cells of SHR. We hypothesize that these changes are due to an increase in membrane Ca2+ channel density and possibly function in vascular myocytes from hypertensive animals. Several observations using various experimental approaches support this hypothesis: 1 the contractile activity in response to depolarizing stimuli is increased in arteries from hypertensive animals demonstrating increased voltage-dependent Ca2+ channel activity in hypertension; 2 Ca2+ channel agonists such as Bay K 8644 produce contractions in isolated arterial segments from hypertensive rats and minimal contraction in those from normotensive rats; 3 intracellular Ca2+ concentration is abnormally increased in vascular myocytes from hypertensive animals following treatment with Ca2+ channel agonists and depolarizing interventions, and 4 using the voltage-clamp technique, the inward Ca2+ current in arterial myocytes from hypertensive rats is nearly twice as large as that from myocytes of normotensive rats. We suggest that an alteration in Ca2+ channel function and/or an increase in Ca2+ channel density, resulting from increased channel synthesis or reduced turnover, underlies the increased vascular reactivity characteristic of hypertension

  16. Cardiac tissue engineering: state of the art.

    Science.gov (United States)

    Hirt, Marc N; Hansen, Arne; Eschenhagen, Thomas

    2014-01-17

    The engineering of 3-dimensional (3D) heart muscles has undergone exciting progress for the past decade. Profound advances in human stem cell biology and technology, tissue engineering and material sciences, as well as prevascularization and in vitro assay technologies make the first clinical application of engineered cardiac tissues a realistic option and predict that cardiac tissue engineering techniques will find widespread use in the preclinical research and drug development in the near future. Tasks that need to be solved for this purpose include standardization of human myocyte production protocols, establishment of simple methods for the in vitro vascularization of 3D constructs and better maturation of myocytes, and, finally, thorough definition of the predictive value of these methods for preclinical safety pharmacology. The present article gives an overview of the present state of the art, bottlenecks, and perspectives of cardiac tissue engineering for cardiac repair and in vitro testing.

  17. Validation of an in vitro contractility assay using canine ventricular myocytes

    Energy Technology Data Exchange (ETDEWEB)

    Harmer, A.R., E-mail: alex.harmer@astrazeneca.com; Abi-Gerges, N.; Morton, M.J.; Pullen, G.F.; Valentin, J.P.; Pollard, C.E.

    2012-04-15

    Measurement of cardiac contractility is a logical part of pre-clinical safety assessment in a drug discovery project, particularly if a risk has been identified or is suspected based on the primary- or non-target pharmacology. However, there are limited validated assays available that can be used to screen several compounds in order to identify and eliminate inotropic liability from a chemical series. We have therefore sought to develop an in vitro model with sufficient throughput for this purpose. Dog ventricular myocytes were isolated using a collagenase perfusion technique and placed in a perfused recording chamber on the stage of a microscope at ∼ 36 °C. Myocytes were stimulated to contract at a pacing frequency of 1 Hz and a digital, cell geometry measurement system (IonOptix™) was used to measure sarcomere shortening in single myocytes. After perfusion with vehicle (0.1% DMSO), concentration–effect curves were constructed for each compound in 4–30 myocytes taken from 1 or 2 dog hearts. The validation test-set was 22 negative and 8 positive inotropes, and 21 inactive compounds, as defined by their effect in dog, cynolomolgous monkey or humans. By comparing the outcome of the assay to the known in vivo contractility effects, the assay sensitivity was 81%, specificity was 75%, and accuracy was 78%. With a throughput of 6–8 compounds/week from 1 cell isolation, this assay may be of value to drug discovery projects to screen for direct contractility effects and, if a hazard is identified, help identify inactive compounds. -- Highlights: ► Cardiac contractility is an important physiological function of the heart. ► Assessment of contractility is a logical part of pre-clinical drug safety testing. ► There are limited validated assays that predict effects of compounds on contractility. ► Using dog myocytes, we have developed an in vitro cardiac contractility assay. ► The assay predicted the in vivo contractility with a good level of accuracy.

  18. Expression of Rho/Rho kinase of cardiac myocyte of heart failure model of pressure overload rats and intervention of fasudil%压力负荷心力衰竭大鼠心肌细胞内Rho/Rho激酶的表达及药物干预

    Institute of Scientific and Technical Information of China (English)

    张曼; 曾定尹

    2005-01-01

    目的探讨升主动脉缩窄压力超负荷心力衰竭大鼠心肌细胞内Rho/Rho激酶的表达及法舒地尔(fasudil)--Rho/Rho激酶拮抗剂对心力衰竭的影响.方法制备升主动脉缩窄大鼠心力衰竭及假手术组(S组)模型.将升主动脉缩窄术后Wistar雌性大鼠随机分为2组,一组为心力衰竭组(H组),给予生理盐水0.1ml,腹腔注射,每日2次;一组为fasudil治疗组(F组),治疗组给予fasudil 5 mg/Kg,腹腔注射,每日2次;治疗4周.H组、F组及S组每组各10只大鼠.观察各组大鼠各项指标变化.结果H组鼠心肌细胞RhoA,Rho激酶mRNA表达显著增高,F组心肌细胞RhoA mRNA,Rho激酶mRNA表达下降.结论心肌细胞RhoA、Rho激酶表达与充血性心力衰竭密切相关,法舒地尔可有效降低心肌细胞内RhoA mRNA,Rho激酶mRNA表达,缓解心力衰竭症状,可能为一种新的、有效的治疗心力衰竭的血管扩张剂.%Objective: To study the expression of Rho/Rho kinase of cardiac myocyte of heart failure pressure overload rat models subsequent to coarctation of ascending aorta and the effects of fasudil on heart failure. Methods:A model of heart failure induced by coarctation of ascending aorta was used in this study. 20 female wistar operation rats were divided randomly into two groups (n =10). Heart failure (Natrii chloridi, 0.1 ml), fasudil (5 mg/Kg), Bid i.p,20 weeks after coarctation of ascending aorta operation, 10 agematched sham operation group as control. Treatment time was 4 weeks. Hemodynamics, ratio of LV weight to body weight, expression of RhoA and Rho kinase mRNA were investigated in the two groups and sham operation group. Results: RhoA, Rho kinase mRNA level were higher in heart failure when compared with sham. Fasudil could change the expression of RhoA, Rho kinase mRNA level.Conclusion: These results indicate that heart failure is probably related to activating of RhoA, Rho kinase. Fasudil may contribute to the observed beneficial effects on heart

  19. The effect of integrated cardiac rehabilitation versus treatment as usual for atrial fibrillation patients treated with ablation

    DEFF Research Database (Denmark)

    Risom, Signe Stelling; Zwisler, Ann-Dorth Olsen; Rasmussen, Trine Bernholdt

    2013-01-01

    to be physically active due to fear of triggering fibrillation. Small trials indicate that exercise training has a positive effect on exercise capacity and mental health, and both patients with recurrent atrial fibrillation and in sinus rhythm may benefit from rehabilitation in managing life after ablation...... measure is exercise capacity measured by the VO(2) peak. The secondary outcome measure is self-rated mental health measured by the Short Form 36 questionnaire. Postintervention, qualitative interviews will be conducted in 10% of the intervention group. ETHICS AND DISSEMINATION: The protocol is approved....... No randomised trials have been published on cardiac rehabilitation for atrial fibrillation patients treated with ablation that includes exercise and psychoeducational components. AIM: To test the effects of an integrated cardiac rehabilitation programme versus treatment as usual for patients with atrial...

  20. Integrative Analysis of PRKAG2 Cardiomyopathy iPS and Microtissue Models Identifies AMPK as a Regulator of Metabolism, Survival, and Fibrosis

    Directory of Open Access Journals (Sweden)

    J. Travis Hinson

    2016-12-01

    Full Text Available AMP-activated protein kinase (AMPK is a metabolic enzyme that can be activated by nutrient stress or genetic mutations. Missense mutations in the regulatory subunit, PRKAG2, activate AMPK and cause left ventricular hypertrophy, glycogen accumulation, and ventricular pre-excitation. Using human iPS cell models combined with three-dimensional cardiac microtissues, we show that activating PRKAG2 mutations increase microtissue twitch force by enhancing myocyte survival. Integrating RNA sequencing with metabolomics, PRKAG2 mutations that activate AMPK remodeled global metabolism by regulating RNA transcripts to favor glycogen storage and oxidative metabolism instead of glycolysis. As in patients with PRKAG2 cardiomyopathy, iPS cell and mouse models are protected from cardiac fibrosis, and we define a crosstalk between AMPK and post-transcriptional regulation of TGFβ isoform signaling that has implications in fibrotic forms of cardiomyopathy. Our results establish critical connections among metabolic sensing, myocyte survival, and TGFβ signaling.

  1. SKF-96365 strongly inhibits voltage-gated sodium current in rat ventricular myocytes.

    Science.gov (United States)

    Chen, Kui-Hao; Liu, Hui; Yang, Lei; Jin, Man-Wen; Li, Gui-Rong

    2015-06-01

    SKF-96365 (1-(beta-[3-(4-methoxy-phenyl) propoxy]-4-methoxyphenethyl)-1H-imidazole hydrochloride) is a general TRPC channel antagonist commonly used to characterize the potential functions of TRPC channels in cardiovascular system. Recent reports showed that SKF-96365 induced a reduction in cardiac conduction. The present study investigates whether the reduced cardiac conduction caused by SKF-96365 is related to the blockade of voltage-gated sodium current (I Na) in rat ventricular myocytes using the whole-cell patch voltage-clamp technique. It was found that SKF-96365 inhibited I Na in rat ventricular myocytes in a concentration-dependent manner. The compound (1 μM) negatively shifted the potential of I Na availability by 9.5 mV, increased the closed-state inactivation of I Na, and slowed the recovery of I Na from inactivation. The inhibition of cardiac I Na by SKF-96365 was use-dependent and frequency-dependent, and the IC₅₀ was decreased from 1.36 μM at 0.5 Hz to 1.03, 0.81, 0.61, 0.56 μM at 1, 2, 5, 10 Hz, respectively. However, the selective TRPC3 antagonist Pyr3 decreased cardiac I Na by 8.5% at 10 μM with a weak use and frequency dependence. These results demonstrate that the TRPC channel antagonist SKF-96365 strongly blocks cardiac I Na in use-dependent and frequency-dependent manners. Caution should be taken for interpreting the alteration of cardiac electrical activity when SKF-96365 is used in native cells as a TRPC antagonist.

  2. Spiral-wave dynamics in a mathematical model of human ventricular tissue with myocytes and fibroblasts.

    Science.gov (United States)

    Nayak, Alok Ranjan; Shajahan, T K; Panfilov, A V; Pandit, Rahul

    2013-01-01

    Cardiac fibroblasts, when coupled functionally with myocytes, can modulate the electrophysiological properties of cardiac tissue. We present systematic numerical studies of such modulation of electrophysiological properties in mathematical models for (a) single myocyte-fibroblast (MF) units and (b) two-dimensional (2D) arrays of such units; our models build on earlier ones and allow for zero-, one-, and two-sided MF couplings. Our studies of MF units elucidate the dependence of the action-potential (AP) morphology on parameters such as [Formula: see text], the fibroblast resting-membrane potential, the fibroblast conductance [Formula: see text], and the MF gap-junctional coupling [Formula: see text]. Furthermore, we find that our MF composite can show autorhythmic and oscillatory behaviors in addition to an excitable response. Our 2D studies use (a) both homogeneous and inhomogeneous distributions of fibroblasts, (b) various ranges for parameters such as [Formula: see text], and [Formula: see text], and (c) intercellular couplings that can be zero-sided, one-sided, and two-sided connections of fibroblasts with myocytes. We show, in particular, that the plane-wave conduction velocity [Formula: see text] decreases as a function of [Formula: see text], for zero-sided and one-sided couplings; however, for two-sided coupling, [Formula: see text] decreases initially and then increases as a function of [Formula: see text], and, eventually, we observe that conduction failure occurs for low values of [Formula: see text]. In our homogeneous studies, we find that the rotation speed and stability of a spiral wave can be controlled either by controlling [Formula: see text] or [Formula: see text]. Our studies with fibroblast inhomogeneities show that a spiral wave can get anchored to a local fibroblast inhomogeneity. We also study the efficacy of a low-amplitude control scheme, which has been suggested for the control of spiral-wave turbulence in mathematical models for cardiac

  3. Proteome- and transcriptome-driven reconstruction of the human myocyte metabolic network and its use for identification of markers for diabetes

    DEFF Research Database (Denmark)

    Väremo, Leif; Scheele, Camilla; Broholm, Christa

    2015-01-01

    -scale metabolic models (GEMs) provide a network context for the integration of high-throughput data. We generated myocyte-specific RNA-sequencing data and investigated their correlation with proteome data. These data were then used to reconstruct a comprehensive myocyte GEM. Next, we performed a meta......-analysis of six studies comparing muscle transcription in T2D versus healthy subjects. Transcriptional changes were mapped on the myocyte GEM, revealing extensive transcriptional regulation in T2D, particularly around pyruvate oxidation, branched-chain amino acid catabolism, and tetrahydrofolate metabolism...

  4. Erythropoietin preserves the integrity and quality of organs for transplantation after cardiac death.

    Science.gov (United States)

    Maio, Rui; Sepodes, Bruno; Patel, Nimesh S A; Thiemermann, Christoph; Mota-Filipe, Helder; Costa, Paulo

    2011-02-01

    Previous studies have shown that treatment with erythropoietin (EPO) exerts important cytoprotective and antiapoptotic effects. Donor organs recovered after cardiac death (DCD) can alleviate the shortage of organs required for transplantation. However, organs obtained subsequent to cardiac death demonstrate an increased incidence of delayed graft function and primary nonfunction. The aim of this study was to determine the effects of EPO administration to the donor in a porcine model of kidney transplantation under DCD conditions. Landrace pigs received 1,000 IU/kg i.v. EPO 30 min before cardiac arrest. Kidneys were then subjected to 30 min of warm ischemia and were transplanted after 24 h of cold storage. Renal dysfunction, injury, and inflammation were evaluated 4 h after transplantation. Transplantation of kidneys from DCD resulted in significant renal dysfunction, injury, and inflammation. This study provides the first evidence that pretreatment of the donor with a single pharmacologically relevant dose of EPO causes substantial attenuation of the dysfunction and injury associated with the transplantation of kidneys recovered after cardiac death.

  5. Echocardiography integrated ACLS protocol versus conventional cardiopulmonary resuscitation in patients with pulseless electrical activity cardiac arrest

    Institute of Scientific and Technical Information of China (English)

    Mojtaba Chardoli; Farhad Heidari; Helaleh Rabiee; Mahdi Sharif-Alhoseini; Hamid Shokoohi; Vafa Rahimi-Movaghar

    2012-01-01

    Objective: To examine the utility of bedside echocardiography in detecting the reversible causes of pulseless electrical activity (PEA) cardiac arrest and predicting the resuscitation outcomes.Methods: In this prospective interventional study,patients presenting with PEA cardiac arrest were randomized into two groups.In Group A,ultrasound trained emergency physicians performed echocardiography evaluating cardiac activity,right ventricle dilation,left ventricle function,pericardial effusion/tamponade and ⅣC size along with the advanced cardiac life support (ACLS) protocol.Patients in Group B solely underwent ACLS protocol without applying echocardiography.The presence or absence of mechanical ventricular activity (MVA) and evidences of PEA reversible causes were recorded.The return of spontaneous circulation (ROSC) and death were evaluated in both groups.Results: One hundred patients with the mean age of (58±6.1) years were enrolled in this study.Fifty patients (Group A) had echocardiography detected in parallel with cardiopulmonary resuscitation (CPR).Among them,7 patients (14%) had pericardial effusion,11 (22%) had hypovolemia,and 39 (78%) were revealed the presence of MVA.In the pseudo PEA subgroup (presence of MVA),43% had ROSC (positive predictive value) and in the true PEA subgroup with cardiac standstill (absence of MVA),there was no recorded ROSC (negative predictive value).Among patients in Group B,no reversible etiology was detected.There was no significant difference in resuscitation results between Groups A and B observed (P=0.52).Conclusion: Bedside echocardiography can identify some reversible causes of PEA.However,there are no significant changes in survival outcome between the echo group and those with traditional CPR.

  6. Effects of acetylcholine and noradrenalin on action potentials of isolated rabbit sinoatrial and atrial myocytes

    Directory of Open Access Journals (Sweden)

    Arie O. Verkerk

    2012-05-01

    Full Text Available The autonomic nervous system controls heart rate and contractility through sympathetic and parasympathetic inputs to the cardiac tissue, with acetylcholine (ACh and noradrenalin (NA as the chemical transmitters. In recent years, it has become clear that specific Regulators of G protein Signalling proteins (RGS proteins suppress muscarinic sensitivity and parasympathetic tone, identifying RGS proteins as intriguing potential therapeutic targets. In the present study, we have identified the effects of 1 µM ACh and 1 µM NA on the intrinsic action potentials of sinotrial (SA nodal and atrial myocytes. Single cells were enzymatically isolated from the SA node or from the left atrium of rabbit hearts. Action potentials were recorded using the amphotericin-perforated patch-clamp technique in the absence and presence of ACh, NA or a combination of both. In SA nodal myocytes, ACh increased cycle length and decreased diastolic depolarization rate, whereas NA decreased cycle length and increased diastolic depolarization rate. Both ACh and NA increased maximum upstroke velocity. Furthermore, ACh hyperpolarized the maximum diastolic potential. In atrial myocytes stimulated at 2 Hz, both ACh and NA hyperpolarized the maximum diastolic potential, increased the action potential amplitude, and increased the maximum upstroke velocity. Action potential duration at 50 and 90% repolarization was decreased by ACh, but increased by NA. The effects of both ACh and NA on action potential duration showed a dose dependence in the range of 1–1,000 nM, while a clear-cut frequency dependence in the range of 1–4 Hz was absent. Intermediate results were obtained in the combined presence of ACh and NA in both SA nodal and atrial myocytes. Our data uncover the extent to which SA nodal and atrial action potentials are intrinsically dependent on ACh, NA or a combination of both and may thus guide further experiments with RGS proteins.

  7. Atrial myocyte function and Ca2+ handling is associated with inborn aerobic capacity.

    Directory of Open Access Journals (Sweden)

    Anne Berit Johnsen

    Full Text Available Although high aerobic capacity is associated with effective cardiac function, the effect of aerobic capacity on atrial function, especially in terms of cellular mechanisms, is not known. We aimed to investigate whether rats with low inborn maximal oxygen uptake (VO2 max had impaired atrial myocyte contractile function when compared to rats with high inborn VO2 max.Atrial myocyte function was depressed in Low Capacity Runners (LCR relative to High Capacity Runners (HCR which was associated with impaired Ca(2+ handling. Fractional shortening was 52% lower at 2 Hz and 60% lower at 5 Hz stimulation while time to 50% relengthening was 43% prolonged and 55% prolonged, respectively. Differences in Ca(2+ amplitude and diastolic Ca(2+ level were observed at 5 Hz stimulation where Ca(2+ amplitude was 70% lower and diastolic Ca(2+ level was 11% higher in LCR rats. Prolonged time to 50% Ca(2+ decay was associated with reduced sarcoplasmic reticulum (SR Ca(2+ ATPase function in LCR (39%. Na(+/Ca(2+ exchanger activity was comparable between the groups. Diastolic SR Ca(2+ leak was increased by 109%. This could be partly explained by increased ryanodine receptors phosphorylation at the Ca(2+-calmodulin-dependent protein kinase-II specific Ser-2814 site in LCR rats. T-tubules were present in 68% of HCR cells whereas only 33% LCR cells had these structures. In HCR, the significantly higher numbers of cells with T-tubules were combined with greater numbers of myocytes where Ca(2+ release in the cell occurred simultaneously in central and peripheral regions, giving rise to faster and more spatial homogenous Ca(2+-signal onset.This data demonstrates that contrasting for low or high aerobic capacity leads to diverse functional and structural remodelling of atrial myocytes, with impaired contractile function in LCR compared to HCR rats.

  8. Cardiac cameras.

    Science.gov (United States)

    Travin, Mark I

    2011-05-01

    Cardiac imaging with radiotracers plays an important role in patient evaluation, and the development of suitable imaging instruments has been crucial. While initially performed with the rectilinear scanner that slowly transmitted, in a row-by-row fashion, cardiac count distributions onto various printing media, the Anger scintillation camera allowed electronic determination of tracer energies and of the distribution of radioactive counts in 2D space. Increased sophistication of cardiac cameras and development of powerful computers to analyze, display, and quantify data has been essential to making radionuclide cardiac imaging a key component of the cardiac work-up. Newer processing algorithms and solid state cameras, fundamentally different from the Anger camera, show promise to provide higher counting efficiency and resolution, leading to better image quality, more patient comfort and potentially lower radiation exposure. While the focus has been on myocardial perfusion imaging with single-photon emission computed tomography, increased use of positron emission tomography is broadening the field to include molecular imaging of the myocardium and of the coronary vasculature. Further advances may require integrating cardiac nuclear cameras with other imaging devices, ie, hybrid imaging cameras. The goal is to image the heart and its physiological processes as accurately as possible, to prevent and cure disease processes.

  9. Myocardial Fibrosis in Hypertrophic Cardiomyopathy Demonstrated by Integrated Cardiac F-18 FDG PET/MR

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Eunjung; Lee, Sanghee; Cho, Ihnho [Yeungnam Univ., Daegu (Korea, Republic of)

    2013-09-15

    Hypertrophic cardiomyopathy (HCM) is a common condition defined as a diffuse or segmental left ventricular (LV) hypertrophy with a nondilated and hyperdynamic chamber as well as cardiac arrhythmias. Cardiac MR (CMR) imaging is a key modality for evaluation of HCM. In addition to the assessment of LV wall thickness, LV function and aortic flow, CMR is capable of estimation of late gadolinium enhancement (LGE) in affected myocardium which has been shown to have a direct correlation with incidence and severity of arrhythmias in HCM. In patients with HCM, LGE on CMR is presumed to represent intramyocardial fibrosis. Meanwhile, F-18 FDG myocardial PET has been sporadically studied in HCM, mostly for evaluation of the metabolic status of a hypertrophic myocardial segment, especially after interventions or to demonstrate partial myocardial fibrosis. We presented here the case of a 25-year-old male patient referred for simultaneous F-18 FDG cardiac PET/MR for the evaluation of septal hypertrophy. The PET/MR revealed myocardial fibrosis in the septum associated with FDG-defect and LGE.

  10. Voltage and Calcium Dual Channel Optical Mapping of Cultured HL-1 Atrial Myocyte Monolayer

    Science.gov (United States)

    Zhao, Weiwei; Fast, Vladimir G.; Ye, Tong; Ai, Xun

    2015-01-01

    Optical mapping has proven to be a valuable technique to detect cardiac electrical activity on both intact ex vivo hearts and in cultured myocyte monolayers. HL-1 cells have been widely used as a 2-Dimensional cellular model for studying diverse aspects of cardiac physiology. However, it has been a great challenge to optically map calcium (Ca) transients and action potentials simultaneously from the same field of view in a cultured HL-1 atrial cell monolayer. This is because special handling and care is required to prepare healthy cells that can be electrically captured and optically mapped. Therefore, we have developed an optimal working protocol for dual channel optical mapping. In this manuscript, we have described in detail how to perform the dual channel optical mapping experiment. This protocol is a useful tool to enhance the understanding of action potential propagation and Ca kinetics in arrhythmia development. PMID:25867896

  11. Tetrahydroacridine inhibits voltage-dependent Na+ current in guinea-pig ventricular myocytes

    Institute of Scientific and Technical Information of China (English)

    Wei WANG; Yi-ping WANG; Guo-yuan HU

    2004-01-01

    AIM: To study the effects of tetrahydroacridine (tacrine) on voltage-gated Na+ channels in cardiac tissues.METHODS: Single ventricular myocytes were enzymatically dissociated from adult guinea-pig heart. Voltagedependent Na+ current was recorded using whole cell voltage-clamp technique. RESULTS: (1) Tacrine reversibly inhibited Na+ current with an IC50 value of 120 μmol/L (95 % confidence range: 108-133 μmol/L). (2) The inhibitory effects of tacrine on Na+ current exhibited both a tonic nature and use-dependence. (3) Tacrine at 100 μmol/L caused a negative shift (about 10 mV) in the voltage-dependence of steady-state inactivation of Na+ current, and retarded its recovery from inactivation, but did not affect its activation curve. (4) Intracellular application of tacrine significantly inhibited Na+ current. CONCLUSION: In addition to blocking other voltage-gated ion channels,tacrine blocked Na+ channels in guinea-pig ventricular myocytes. Tactine acted as inactivation stabilizer of Na+channels in cardiac tissues.

  12. Modeling CICR in rat ventricular myocytes: voltage clamp studies

    Directory of Open Access Journals (Sweden)

    Palade Philip T

    2010-11-01

    Full Text Available Abstract Background The past thirty-five years have seen an intense search for the molecular mechanisms underlying calcium-induced calcium-release (CICR in cardiac myocytes, with voltage clamp (VC studies being the leading tool employed. Several VC protocols including lowering of extracellular calcium to affect Ca2+ loading of the sarcoplasmic reticulum (SR, and administration of blockers caffeine and thapsigargin have been utilized to probe the phenomena surrounding SR Ca2+ release. Here, we develop a deterministic mathematical model of a rat ventricular myocyte under VC conditions, to better understand mechanisms underlying the response of an isolated cell to calcium perturbation. Motivation for the study was to pinpoint key control variables influencing CICR and examine the role of CICR in the context of a physiological control system regulating cytosolic Ca2+ concentration ([Ca2+]myo. Methods The cell model consists of an electrical-equivalent model for the cell membrane and a fluid-compartment model describing the flux of ionic species between the extracellular and several intracellular compartments (cell cytosol, SR and the dyadic coupling unit (DCU, in which resides the mechanistic basis of CICR. The DCU is described as a controller-actuator mechanism, internally stabilized by negative feedback control of the unit's two diametrically-opposed Ca2+ channels (trigger-channel and release-channel. It releases Ca2+ flux into the cyto-plasm and is in turn enclosed within a negative feedback loop involving the SERCA pump, regulating[Ca2+]myo. Results Our model reproduces measured VC data published by several laboratories, and generates graded Ca2+ release at high Ca2+ gain in a homeostatically-controlled environment where [Ca2+]myo is precisely regulated. We elucidate the importance of the DCU elements in this process, particularly the role of the ryanodine receptor in controlling SR Ca2+ release, its activation by trigger Ca2+, and its

  13. Effects of Angiotensin Ⅱ on Expression of the Gap Junction Channel Protein Connexin 43 in Neonatal Rat Ventricular Myocytes

    Institute of Scientific and Technical Information of China (English)

    Jun Yang; Wei Wu

    2007-01-01

    To study the effects of angiotensin Ⅱ,as a mediator of cardiac hypertrophy,on expression of connexin 43 (Cx43) in cultured neonatal rat ventricular myocytes and correlation of expression of Cx43 and cardiomyocyte hypertrophy.Methods Cardiomyocytes were isolated from newborn SD rats.Angiotensin Ⅱ was added into the media to induce myocyte hypertrophy.Cultures were exposed to 10 ~6 mol/L angiotensin Ⅱ for 72 h,Cx43 expression was characterized by RT-PCR and Immunofluorescence methods.Results Immunofluorescence analysis revealed decreased Cx43 immunoreactivity in cells treated for 72 h with angiotensin Ⅱ.RT-PCR analysis demonstrated there was an obvious decrease of Cx43 mRNA level in cells exposed to angiotensin Ⅱ for 72 h.The changes of expression of connexin 43 were related to its entrance into S phase of the cell cycle.Cultured neonatal rat cardiomyocytes were exposed for 72 h to increase concentrations of angiotensin Ⅱ ( 1.0 × 10-9 ~ 1.0 × 10-6mol/L),resulting in significantly decreased Cx43 expression.Conclusions Angiotensin Ⅱ leads to a concentration-dependent decrease in Cx43 protein in cultured neonatal rat ventricular myocytes by decreasing Cx43 mRNA synthesis.Signal transduction pathways activated by angiotensin Ⅱ under pathophysiologic conditions of cardiac hypertrophy could initiate remodeling of gap junctions.

  14. Longstanding hyperthyroidism is associated with normal or enhanced intrinsic cardiomyocyte function despite decline in global cardiac function.

    Directory of Open Access Journals (Sweden)

    Nathan Y Weltman

    Full Text Available Thyroid hormones (THs play a pivotal role in cardiac homeostasis. TH imbalances alter cardiac performance and ultimately cause cardiac dysfunction. Although short-term hyperthyroidism typically leads to heightened left ventricular (LV contractility and improved hemodynamic parameters, chronic hyperthyroidism is associated with deleterious cardiac consequences including increased risk of arrhythmia, impaired cardiac reserve and exercise capacity, myocardial remodeling, and occasionally heart failure. To evaluate the long-term consequences of chronic hyperthyroidism on LV remodeling and function, we examined LV isolated myocyte function, chamber function, and whole tissue remodeling in a hamster model. Three-month-old F1b hamsters were randomized to control or 10 months TH treatment (0.1% grade I desiccated TH. LV chamber remodeling and function was assessed by echocardiography at 1, 2, 4, 6, 8, and 10 months of treatment. After 10 months, terminal cardiac function was assessed by echocardiography and LV hemodynamics. Hyperthyroid hamsters exhibited significant cardiac hypertrophy and deleterious cardiac remodeling characterized by myocyte lengthening, chamber dilatation, decreased relative wall thickness, increased wall stress, and increased LV interstitial fibrotic deposition. Importantly, hyperthyroid hamsters demonstrated significant LV systolic and diastolic dysfunction. Despite the aforementioned remodeling and global cardiac decline, individual isolated cardiac myocytes from chronically hyperthyroid hamsters had enhanced function when compared with myocytes from untreated age-matched controls. Thus, it appears that long-term hyperthyroidism may impair global LV function, at least in part by increasing interstitial ventricular fibrosis, in spite of normal or enhanced intrinsic cardiomyocyte function.

  15. Evaluation of cardiac sympathetic neuronal integrity in diabetic patients using iodine-123 metaiodobenzylguanidine

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sun Jung [Department of Diagnostic Radiology and Nuclear Medicine, Yonsei University, College of Medicine, 134 Shincheon-dong, Seodaemun-gu, Seoul, 120-752 (Korea, Republic of); Lee, Jong Doo [Department of Diagnostic Radiology and Nuclear Medicine, Yonsei University, College of Medicine, 134 Shincheon-dong, Seodaemun-gu, Seoul, 120-752 (Korea, Republic of); Ryu, Young Hoon [Department of Diagnostic Radiology and Nuclear Medicine, Yonsei University, College of Medicine, 134 Shincheon-dong, Seodaemun-gu, Seoul, 120-752 (Korea, Republic of); Jeon, Pyoung [Department of Diagnostic Radiology and Nuclear Medicine, Yonsei University, College of Medicine, 134 Shincheon-dong, Seodaemun-gu, Seoul, 120-752 (Korea, Republic of); Shim, Yong Woon [Department of Diagnostic Radiology and Nuclear Medicine, Yonsei University, College of Medicine, 134 Shincheon-dong, Seodaemun-gu, Seoul, 120-752 (Korea, Republic of); Yoo, Hyung Sik [Department of Diagnostic Radiology and Nuclear Medicine, Yonsei University, College of Medicine, 134 Shincheon-dong, Seodaemun-gu, Seoul, 120-752 (Korea, Republic of); Park, Chang Yun [Department of Diagnostic Radiology and Nuclear Medicine, Yonsei University, College of Medicine, 134 Shincheon-dong, Seodaemun-gu, Seoul, 120-752 (Korea, Republic of); Lim, Seung Gil [Department of Endocrinology, Yonsei University, College of Medicine, 134 Shincheon-dong, Seodaemun-gu, Seoul, 120-752 (Korea, Republic of)

    1996-04-01

    Autonomic dysfunction is associated with increased mortality in diabetic patients. To evaluate the cardiac autonomic dysfunction in these patients, a prospective study was undertaken using iodine-123 metaiodobenzylguanidine (MIBG) single-photon emission tomography (SPET). The study groups consisted of ten diabetic patients with cardiac autonomic neuropathy (group I) and six without autonomic neuropathy (group II). Autonomic nervous function tests, thallium scan, radionuclide ventriculographic data including ejection fraction and wall motion study, and 24-h urine catecholamine levels were evaluated. {sup 123}I-MIBG SPET was performed at 30 min and 4 h following injection of 3 mCi of {sup 123}I-MIBG in groups I and II and in normal subjects (n=4). On planar images, the heart to mediastinum (H/M) ratio was measured. Defect pattern and severity of MIBG uptake were qualitatively analysed on SPET. Compared with control subjects, diabetic patients had a reduced H/M ratio regardless of the presence of clinical autonomic neuropathy. There was no difference in H/M ratio between groups I and II. On SPET images, focal or diffuse defects were demonstrated in all patients in group I, and in five of the six patients in group II. The extent of defects tended to be more pronounced in group I than in group II. In conclusion, {sup 123}I-MIBG scan was found to be a more sensitive method than clinical autonomic nervous function tests for the detection of autonomic neuropathy in diabetes. (orig.). With 3 figs., 1 tab.

  16. A survey of membrane oxygenator heat-exchanger integrity testing at cardiac surgery centres in Great Britain and Ireland.

    Science.gov (United States)

    Carlton, Matthew; Campbell, John

    2013-11-01

    Membrane oxygenator heat exchanger (HE) device failure is reported to be very low for both short- and long-term extracorporeal devices. All oxygenator manufacturers provide instructions for leak testing of their HE devices prior to patient use. In addition to these recommendations, since 2006 at Nottingham University Hospitals (NUH) we have also additionally pressure tested HE devices prior to use. We conducted a national survey of cardiac centers in Great Britain and Ireland to determine the methods undertaken in individual centers for validation of the integrity of HE devices. Furthermore, we also collected information on the routine maintenance techniques utilized within these centers to inhibit microbial growth in the water used in the heater-cooler units (HCUs). In total, 34 responses were collected from the 57 centers performing cardiac surgery, producing a response rate of 60%. Of the responding centers, 71% are adhering to manufacturer's recommended guidelines of circulating the water through the device for 5 minutes. Of these centers, 17% reported detecting a leak between the HE and membrane compartment of the oxygenator. In responding centers, 29% reported using the pressure test technique. In the centers utilizing pressure testing, 60% reported detecting a leak. This survey reports an association of a greater HE leak detection rate using the pressure test technique compared to using water testing in isolation (p = 0.034). We believe the pressure testing method provides the perfusionist with confidence in the integrity of the HE for short- and long-term circulatory support devices prior to use in both elective and emergency situations.

  17. Cardiac mitochondria exhibit dynamic functional clustering

    Directory of Open Access Journals (Sweden)

    Felix Tobias Kurz

    2014-09-01

    Full Text Available Multi-oscillatory behavior of mitochondrial inner membrane potential ΔΨm in self-organized cardiac mitochondrial networks can be triggered by metabolic or oxidative stress. Spatio-temporal analyses of cardiac mitochondrial networks have shown that mitochondria are heterogeneously organized in synchronously oscillating clusters in which the mean cluster frequency and size are inversely correlated, thus suggesting a modulation of cluster frequency through local inter-mitochondrial coupling. In this study, we propose a method to examine the mitochondrial network's topology through quantification of its dynamic local clustering coefficients. Individual mitochondrial ΔΨm oscillation signals were identified for each cardiac myocyte and cross-correlated with all network mitochondria using previously described methods (Kurz et al., 2010. Time-varying inter-mitochondrial connectivity, defined for mitochondria in the whole network whose signals are at least 90% correlated at any given time point, allowed considering functional local clustering coefficients. It is shown that mitochondrial clustering in isolated cardiac myocytes changes dynamically and is significantly higher than for random mitochondrial networks that are constructed using the Erdös-Rényi model based on the same sets of vertices. The network's time-averaged clustering coefficient for cardiac myocytes was found to be 0.500 ± 0.051 (N=9 versus 0.061 ± 0.020 for random networks, respectively. Our results demonstrate that cardiac mitochondria constitute a network with dynamically connected constituents whose topological organization is prone to clustering. Cluster partitioning in networks of coupled oscillators has been observed in scale-free and chaotic systems and is therefore in good agreement with previous models of cardiac mitochondrial networks (Aon et al., 2008.

  18. Rational promoter selection for gene transfer into cardiac cells

    NARCIS (Netherlands)

    Maass, A; Langer, SJ; Oberdorf-Maass, S; Bauer, S; Neyses, L; Leinwand, LA

    2003-01-01

    Cardiomyocytes (CMCs) are extremely difficult to transfect with non-viral techniques, but they are efficiently infected by adenoviruses. The most commonly used promoters to drive protein expression in cardiac myocytes are of viral origin, since they are believed to be constitutively active and minim

  19. Cardiac troponin T mutations in Chinese patients with hypertrophic cardiomyopathy

    Institute of Scientific and Technical Information of China (English)

    吴恒芳; 杨笛; 万文辉; 卞智萍; 徐晋丹; 马文珠; 张寄南

    2004-01-01

    @@ Hypertrophic cardiomyopathy (HCM) is a myocardial disorder characterized by unexplained ventricular hypertrophy and myofibrillar disarray, with a prevalence of about 0.2% in general population. HCM is associated with gene abnormalities. Nearly 200 mutations have been described in ten genes in patients with HCM.1 Cardiac troponin T (cTnT) is an essential component of the troponin complex and plays a central role in the calcium regulation of contractions in cardiac myocytes

  20. Laminar arrangement of ventricular myocytes influences electrical behavior of the heart.

    Science.gov (United States)

    Hooks, Darren A; Trew, Mark L; Caldwell, Bryan J; Sands, Gregory B; LeGrice, Ian J; Smaill, Bruce H

    2007-11-01

    The response of the heart to electrical shock, electrical propagation in sinus rhythm, and the spatiotemporal dynamics of ventricular fibrillation all depend critically on the electrical anisotropy of cardiac tissue. A long-held view of cardiac electrical anisotropy is that electrical conductivity is greatest along the myocyte axis allowing most rapid propagation of electrical activation in this direction, and that conductivity is isotropic transverse to the myocyte axis supporting a slower uniform spread of activation in this plane. In this context, knowledge of conductivity in two directions, parallel and transverse to the myofiber axis, is sufficient to characterize the electrical action of the heart. Here we present new experimental data that challenge this view. We have used a novel combination of intramural electrical mapping, and experiment-specific computer modeling, to demonstrate that left ventricular myocardium has unique bulk conductivities associated with three microstructurally-defined axes. We show that voltage fields induced by intramural current injection are influenced by not only myofiber direction, but also the transmural arrangement of muscle layers or myolaminae. Computer models of these experiments, in which measured 3D tissue structure was reconstructed in-silico, best matched recorded voltages with conductivities in the myofiber direction, and parallel and normal to myolaminae, set in the ratio 4:2:1, respectively. These findings redefine cardiac tissue as an electrically orthotropic substrate and enhance our understanding of how external shocks may act to successfully reset the fibrillating heart into a uniform electrical state. More generally, the mechanisms governing the destabilization of coordinated electrical propagation into ventricular arrhythmia need to be evaluated in the light of this discovery.

  1. Aging induces cardiac diastolic dysfunction, oxidative stress, accumulation of advanced glycation endproducts and protein modification.

    Science.gov (United States)

    Li, Shi-Yan; Du, Min; Dolence, E Kurt; Fang, Cindy X; Mayer, Gabriele E; Ceylan-Isik, Asli F; LaCour, Karissa H; Yang, Xiaoping; Wilbert, Christopher J; Sreejayan, Nair; Ren, Jun

    2005-04-01

    Evidence suggests that aging, per se, is a major risk factor for cardiac dysfunction. Oxidative modification of cardiac proteins by non-enzymatic glycation, i.e. advanced glycation endproducts (AGEs), has been implicated as a causal factor in the aging process. This study was designed to examine the role of aging on cardiomyocyte contractile function, cardiac protein oxidation and oxidative modification. Mechanical properties were evaluated in ventricular myocytes from young (2-month) and aged (24-26-month) mice using a MyoCam system. The mechanical indices evaluated were peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR90) and maximal velocity of shortening/relengthening (+/- dL/dt). Oxidative stress and protein damage were evaluated by glutathione and glutathione disulfide (GSH/GSSG) ratio and protein carbonyl content, respectively. Activation of NAD(P)H oxidase was determined by immunoblotting. Aged myocytes displayed a larger cell cross-sectional area, prolonged TR90, and normal PS, +/- dL/dt and TPS compared with young myocytes. Aged myocytes were less tolerant of high stimulus frequency (from 0.1 to 5 Hz) compared with young myocytes. Oxidative stress and protein oxidative damage were both elevated in the aging group associated with significantly enhanced p47phox but not gp91phox expression. In addition, level of cardiac AGEs was approximately 2.5-fold higher in aged hearts than young ones determined by AGEs-ELISA. A group of proteins with a molecular range between 50 and 75 kDa with pI of 4-7 was distinctively modified in aged heart using one- or two-dimension SDS gel electrophoresis analysis. These data demonstrate cardiac diastolic dysfunction and reduced stress tolerance in aged cardiac myocytes, which may be associated with enhanced cardiac oxidative damage, level of AGEs and protein modification by AGEs.

  2. Foxf genes integrate tbx5 and hedgehog pathways in the second heart field for cardiac septation.

    Directory of Open Access Journals (Sweden)

    Andrew D Hoffmann

    2014-10-01

    Full Text Available The Second Heart Field (SHF has been implicated in several forms of congenital heart disease (CHD, including atrioventricular septal defects (AVSDs. Identifying the SHF gene regulatory networks required for atrioventricular septation is therefore an essential goal for understanding the molecular basis of AVSDs. We defined a SHF Hedgehog-dependent gene regulatory network using whole genome transcriptional profiling and GLI-chromatin interaction studies. The Forkhead box transcription factors Foxf1a and Foxf2 were identified as SHF Hedgehog targets. Compound haploinsufficiency for Foxf1a and Foxf2 caused atrioventricular septal defects, demonstrating the biological relevance of this regulatory network. We identified a Foxf1a cis-regulatory element that bound the Hedgehog transcriptional regulators GLI1 and GLI3 and the T-box transcription factor TBX5 in vivo. GLI1 and TBX5 synergistically activated transcription from this cis-regulatory element in vitro. This enhancer drove reproducible expression in vivo in the posterior SHF, the only region where Gli1 and Tbx5 expression overlaps. Our findings implicate Foxf genes in atrioventricular septation, describe the molecular underpinnings of the genetic interaction between Hedgehog signaling and Tbx5, and establish a molecular model for the selection of the SHF gene regulatory network for cardiac septation.

  3. Foxf genes integrate tbx5 and hedgehog pathways in the second heart field for cardiac septation.

    Science.gov (United States)

    Hoffmann, Andrew D; Yang, Xinan Holly; Burnicka-Turek, Ozanna; Bosman, Joshua D; Ren, Xiaomeng; Steimle, Jeffrey D; Vokes, Steven A; McMahon, Andrew P; Kalinichenko, Vladimir V; Moskowitz, Ivan P

    2014-10-01

    The Second Heart Field (SHF) has been implicated in several forms of congenital heart disease (CHD), including atrioventricular septal defects (AVSDs). Identifying the SHF gene regulatory networks required for atrioventricular septation is therefore an essential goal for understanding the molecular basis of AVSDs. We defined a SHF Hedgehog-dependent gene regulatory network using whole genome transcriptional profiling and GLI-chromatin interaction studies. The Forkhead box transcription factors Foxf1a and Foxf2 were identified as SHF Hedgehog targets. Compound haploinsufficiency for Foxf1a and Foxf2 caused atrioventricular septal defects, demonstrating the biological relevance of this regulatory network. We identified a Foxf1a cis-regulatory element that bound the Hedgehog transcriptional regulators GLI1 and GLI3 and the T-box transcription factor TBX5 in vivo. GLI1 and TBX5 synergistically activated transcription from this cis-regulatory element in vitro. This enhancer drove reproducible expression in vivo in the posterior SHF, the only region where Gli1 and Tbx5 expression overlaps. Our findings implicate Foxf genes in atrioventricular septation, describe the molecular underpinnings of the genetic interaction between Hedgehog signaling and Tbx5, and establish a molecular model for the selection of the SHF gene regulatory network for cardiac septation.

  4. Effects of the venom of the spider Ornithoctonus hainana on neonatal rat ventricular myocytes cellular and ionic electrophysiology.

    Science.gov (United States)

    Zhang, Yiya; Liu, Jinyan; Liu, Zhonghua; Wang, Meichi; Wang, Jing; Lu, Shanshan; Zhu, Li; Zeng, Xiongzhi; Liang, Songping

    2014-09-01

    Cardiac ion channels are membrane-spanning proteins that allow the passive movement of ions across the cell membrane along its electrochemical gradient, which regulates the resting membrane potential as well as the shape and duration of the cardiac action potential. Additionally, they have been recognized as potential targets for the actions of neurotransmitters, hormones and drugs of cardiac diseases. Spider venoms contain high abundant of toxins that target diverse ion channels and have been considered as a potential resource of new constituents with specific pharmacological properties. However, few peptides from spider venoms were detected as cardiac channel antagonists. In order to explore the effects of the venom of Ornithoctonus hainana on the action potential and ionic currents of neonatal rat ventricular myocytes (NRVMs), whole cell patch clamp technique was used to record action potential duration (APD), sodium current (INa), L calcium current (ICaL), rapidly activating and inactivating transient outward currents (Ito1), rapid (IKr) and slow (IKs) components of the delayed rectifier currents and the inward rectifier currents (IK1). Our results showed that 100 μg/mL venom obviously prolonged APDs. Significantly, the venom could inhibit INa and ICaL effectively, while no evident inhibitory effects on cardiac K(+) channels (Ito1, Iks, Ikr and Ik1) were observed, suggesting that the venom represented a multifaceted pharmacological profile. The effect of venom on Na(+) and Ca(2+) currents of ventricular myocytes revealed that the hainan venom as a rich resource of cardiac channel antagonists might be valuable tools for the investigation of both channels and drug development.

  5. Biphasic effects of haloperidol on sodium currents in guinea pig ventricular myocytes

    Institute of Scientific and Technical Information of China (English)

    Lu-feng CHENG; Dong YAN; Subat TURDI; Parhat KERRAM

    2007-01-01

    Aim: To study the effects of haloperidol on sodium currents (INa) in guinea pig ventricular myocytes. Method: Whole-cell patch clamp technique was employed to evaluate the effects of haloperidol on INa, in individual ventricular myocytes.Results: Haloperidol (0.1-3 μmol/L) inhibited INa in a concentration-dependent manner with an IC50 of 0.253±0.015 μmol/L. The inhibition rate of haloperidol (0.3 μmol/L) on INa was 22.14%±0.02%, and the maximum conductance was reduced.Haloperidol significantly reduced the midpoints for the activation and inactiva-tion of INa by 2.09 and 4.09 mV, respectively. The time constant of recovery was increased. The increase in time intervals could only recover by 90.14%±1.4% (n=6); however, haloperidol at 0.03 μmol/L enhanced INa conductance. The mid-points for the activation and inactivation of INa were shifted by 1.38 and 5.69 mV,respectively, at this concentration of haloperidol.Conclusion: Haloperidol dis-played a biphasic effect on INa in guinea pig cardiac myocytes. High concentra-tions of haloperidol inhibited INa, while lower concentrations of haloperidol shifted the activation and inactivation curve to the left. Full recovery of recovery curve was not achieved after 0.3 μmol/L haloperidol administration, indicating that the drug affects the inactivated state of sodium channels.

  6. Platelet-derived growth factor receptor-β in myocyte was upregulated by angiotensin II

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    To observe the regulation of platelet-derived growth factor (PDGF) receptor-βin myocyte stimulated by angiotensin II (AngII) at both integrated and cellular levels and reveal the signal transduction mechanism in cell, two kidneys, one clip (2K1C) renal hypertension were performed by placing a sliver clip around the left renal artery. Blood pressure and the ratio of left ventricular weight to body weight were measured at 4 and 8 weeks after operation. The content of AngII in heart was detected by radioimmunology assay; the protein level of PDGF receptor-βin heart was measured by Western blot analysis. The alteration of PDGF receptor-βstimulated by AngII and several inhibitors was observed on cultured neonatal rat ventricular myocyte (NRVM). The content of AngII in heart of 2K1C renal hypertensive rat at 4 and 8 weeks after operation was increased. Compared with sham group, 4 and 8 weeks after operation, PDGF receptor-βin heart of 2K1C group was upregulated by 100.3% and 127.1% (P < 0.05), respectively. This upregulation could be inhibited by captopril. For cultured myocyte, PDGF receptor-βwas increased by 47.1% after being stimulated by AngII and this upregulation could be inhibited by losartan which was an inhibitor of AT1 receptor. PLC inhibitor (U73122) and MEK inhibitor (PD98059) could partly inhibit PDGF receptor-βupregulation induced by AngII. These results suggested that AngII could upregulate PDGF receptor-βin myocyte by its AT1 receptor and this effect was at least partly dependent on PLC and extracellular signal-regulated kinase (ERK).

  7. Calibrated integrated backscatter and myocardial fibrosis in patients undergoing cardiac surgery

    NARCIS (Netherlands)

    Prior, David L; Somaratne, Jithendra B; Jenkins, Alicia J; Yii, Michael; Newcomb, Andrew E; Schalkwijk, Casper G; Black, Mary J; Kelly, Darren J; Campbell, Duncan J

    2015-01-01

    OBJECTIVE: The reported association between calibrated integrated backscatter (cIB) and myocardial fibrosis is based on study of patients with dilated or hypertrophic cardiomyopathy and extensive (mean 15-34%) fibrosis. Its association with lesser degrees of fibrosis is unknown. We examined the rela

  8. The Progress of Perioperative Therapy with Integrative Medicine in the Field of Cardiac Surgery

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ In the 1960s,a number of integrative Chinese and Western medicine (ICWM)surgeons (such as Prof.WU Xian-zhong) first started the application of traditional Chinese medicine (TCM) in acute abdominal surgery,and thus they became the pioneers of perioperative therapy with ICWM.

  9. Cardiac Regeneration and Stem Cells.

    Science.gov (United States)

    Zhang, Yiqiang; Mignone, John; MacLellan, W Robb

    2015-10-01

    After decades of believing the heart loses the ability to regenerate soon after birth, numerous studies are now reporting that the adult heart may indeed be capable of regeneration, although the magnitude of new cardiac myocyte formation varies greatly. While this debate has energized the field of cardiac regeneration and led to a dramatic increase in our understanding of cardiac growth and repair, it has left much confusion in the field as to the prospects of regenerating the heart. Studies applying modern techniques of genetic lineage tracing and carbon-14 dating have begun to establish limits on the amount of endogenous regeneration after cardiac injury, but the underlying cellular mechanisms of this regeneration remained unclear. These same studies have also revealed an astonishing capacity for cardiac repair early in life that is largely lost with adult differentiation and maturation. Regardless, this renewed focus on cardiac regeneration as a therapeutic goal holds great promise as a novel strategy to address the leading cause of death in the developed world.

  10. Larger late sodium current density as well as greater sensitivities to ATX II and ranolazine in rabbit left atrial than left ventricular myocytes.

    Science.gov (United States)

    Luo, Antao; Ma, Jihua; Song, Yejia; Qian, Chunping; Wu, Ying; Zhang, Peihua; Wang, Leilei; Fu, Chen; Cao, Zhenzhen; Shryock, John C

    2014-02-01

    An increase of cardiac late sodium current (INa.L) is arrhythmogenic in atrial and ventricular tissues, but the densities of INa.L and thus the potential relative contributions of this current to sodium ion (Na(+)) influx and arrhythmogenesis in atria and ventricles are unclear. In this study, whole-cell and cell-attached patch-clamp techniques were used to measure INa.L in rabbit left atrial and ventricular myocytes under identical conditions. The density of INa.L was 67% greater in left atrial (0.50 ± 0.09 pA/pF, n = 20) than in left ventricular cells (0.30 ± 0.07 pA/pF, n = 27, P < 0.01) when elicited by step pulses from -120 to -20 mV at a rate of 0.2 Hz. Similar results were obtained using step pulses from -90 to -20 mV. Anemone toxin II (ATX II) increased INa.L with an EC50 value of 14 ± 2 nM and a Hill slope of 1.4 ± 0.1 (n = 9) in atrial myocytes and with an EC50 of 21 ± 5 nM and a Hill slope of 1.2 ± 0.1 (n = 12) in ventricular myocytes. Na(+) channel open probability (but not mean open time) was greater in atrial than in ventricular cells in the absence and presence of ATX II. The INa.L inhibitor ranolazine (3, 6, and 9 μM) reduced INa.L more in atrial than ventricular myocytes in the presence of 40 nM ATX II. In summary, rabbit left atrial myocytes have a greater density of INa.L and higher sensitivities to ATX II and ranolazine than rabbit left ventricular myocytes.

  11. Computational modeling and numerical methods for spatiotemporal calcium cycling in ventricular myocytes

    Directory of Open Access Journals (Sweden)

    Michael eNivala

    2012-05-01

    Full Text Available Intracellular calcium (Ca cycling dynamics in cardiac myocytes is regulated by a complex network of spatially distributed organelles, such as sarcoplasmic reticulum (SR, mitochondria, and myofibrils. In this study, we present a mathematical model of intracellular Ca cycling and numerical and computational methods for computer simulations. The model consists of a coupled Ca release unit (CRU network, which includes a SR domain and a myoplasm domain. Each CRU contains 10 L-type Ca channels and 100 ryanodine receptor channels, with individual channels simulated stochastically using a varient of Gillespie’s method, modified here to handle time-dependent transition rates. Both the SR domain and the myoplasm domain in each CRU are modeled by 5x5x5 voxels to maintain proper Ca diffusion. Advanced numerical algorithms implemented on graphical processing units were used for fast computational simulations. For a myocyte containing 100x20x10 CRUs, a one-second heart time simulation takes about 10 minutes of machine time on a single NVIDIA Tesla C2050. Examples of simulated Ca cycling dynamics, such as Ca sparks, Ca waves, and Ca alternans, are shown.

  12. The role of the Arrhythmia Team, an integrated, multidisciplinary approach to treatment of patients with cardiac arrhythmias: results of the European Heart Rhythm Association survey.

    Science.gov (United States)

    Fumagalli, Stefano; Chen, Jian; Dobreanu, Dan; Madrid, Antonio Hernandez; Tilz, Roland; Dagres, Nikolaos

    2016-04-01

    Management of patients with cardiac arrhythmias is increasingly complex because of continuous technological advance and multifaceted clinical conditions associated with ageing of the population, the presence of co-morbidities and the need for polypharmacy. The aim of this European Heart Rhythm Association Scientific Initiatives Committee survey was to provide an insight into the role of the Arrhythmia Team, an integrated, multidisciplinary approach to management of patients with cardiac arrhythmias. Forty-eight centres from 18 European countries replied to the Web-based questionnaire. The presence of an Arrhythmia Team was reported by 44% of the respondents, whereas 17% were not familiar with this term. Apart from the electrophysiologist, health professionals who should belong to such teams, according to the majority of the respondents, include a clinical cardiologist, a nurse, a cardiac surgeon, a heart failure specialist, a geneticist, and a geriatrician. Its main activity should be dedicated to the management of patients with complex clinical conditions or refractory or inherited forms of arrhythmias. When present, the Arrhythmia Team was considered helpful by 95% of respondents; the majority of centres (79%) agreed that it should be implemented. The Arrhythmia Team seems to be connected to important expectations in the management of cardiac arrhythmias. The efficacy of such an integrated and multidisciplinary approach should be encouraged and tested in clinical practice.

  13. Inflammation and cardiac dysfunction during sepsis, muscular dystrophy, and myocarditis

    Directory of Open Access Journals (Sweden)

    Ying Li

    2013-12-01

    Full Text Available Inflammation plays an important role in cardiac dysfunction under different situations. Acute systemic inflammation occurring in patients with severe burns, trauma, and inflammatory diseases causes cardiac dysfunction, which is one of the leading causes of mortality in these patients. Acute sepsis decreases cardiac contractility and impairs myocardial compliance. Chronic inflammation such as that occurring in Duchenne muscular dystropshy and myocarditis may cause adverse cardiac remodeling including myocyte hypertrophy and death, fibrosis, and altered myocyte function. However, the underlying cellular and molecular mechanisms for inflammatory cardiomyopathy are still controversial probably due to multiple factors involved. Potential mechanisms include the change in circulating blood volume; a direct inhibition of myocyte contractility by cytokines (tumor necrosis factor (TNF-a, interleukin (IL-1b; abnormal nitric oxide and reactive oxygen species (ROS signaling; mitochondrial dysfunction; abnormal excitation-contraction coupling; and reduced calcium sensitivity at the myofibrillar level and blunted b-adrenergic signaling. This review will summarize recent advances in diagnostic technology, mechanisms, and potential therapeutic strategies for inflammation-induced cardiac dysfunction.

  14. The Drosophila Transcription Factors Tinman and Pannier Activate and Collaborate with Myocyte Enhancer Factor-2 to Promote Heart Cell Fate.

    Directory of Open Access Journals (Sweden)

    TyAnna L Lovato

    Full Text Available Expression of the MADS domain transcription factor Myocyte Enhancer Factor 2 (MEF2 is regulated by numerous and overlapping enhancers which tightly control its transcription in the mesoderm. To understand how Mef2 expression is controlled in the heart, we identified a late stage Mef2 cardiac enhancer that is active in all heart cells beginning at stage 14 of embryonic development. This enhancer is regulated by the NK-homeodomain transcription factor Tinman, and the GATA transcription factor Pannier through both direct and indirect interactions with the enhancer. Since Tinman, Pannier and MEF2 are evolutionarily conserved from Drosophila to vertebrates, and since their vertebrate homologs can convert mouse fibroblast cells to cardiomyocytes in different activator cocktails, we tested whether over-expression of these three factors in vivo could ectopically activate known cardiac marker genes. We found that mesodermal over-expression of Tinman and Pannier resulted in approximately 20% of embryos with ectopic Hand and Sulphonylurea receptor (Sur expression. By adding MEF2 alongside Tinman and Pannier, a dramatic expansion in the expression of Hand and Sur was observed in almost all embryos analyzed. Two additional cardiac markers were also expanded in their expression. Our results demonstrate the ability to initiate ectopic cardiac fate in vivo by the combination of only three members of the conserved Drosophila cardiac transcription network, and provide an opportunity for this genetic model system to be used to dissect the mechanisms of cardiac specification.

  15. The effect of Gi-protein inactivation on basal, and β1- and β2AR-stimulated contraction of myocytes from transgenic mice overexpressing the β2-adrenoceptor

    OpenAIRE

    Gong, Haibin; Adamson, Dawn L; Ranu, Hardeep K; Koch, Walter J.; Heubach, Jürgen F; Ravens, Ursula; Zolk, Oliver; Harding, Sian E

    2000-01-01

    The atria and ventricles of transgenic mice (TGβ2) with cardiac overexpression of the human β2-adrenoceptor (β2AR) were initially reported to show maximum contractility in the absence of β-AR stimulation. However, we have previously observed a different phenotype in these mice, with myocytes showing normal contractility but reduced βAR responses. We have investigated the roles of cyclic AMP and Gi in basal and βAR function in these myocytes.ICI 118,551 at inverse agonist concentrations decrea...

  16. Ca(2+)-activated chloride channel activity during Ca(2+) alternans in ventricular myocytes.

    Science.gov (United States)

    Kanaporis, Giedrius; Blatter, Lothar A

    2016-11-01

    Cardiac alternans, defined beat-to-beat alternations in contraction, action potential (AP) morphology or cytosolic Ca transient (CaT) amplitude, is a high risk indicator for cardiac arrhythmias. We investigated mechanisms of cardiac alternans in single rabbit ventricular myocytes. CaTs were monitored simultaneously with membrane currents or APs recorded with the patch clamp technique. A strong correlation between beat-to-beat alternations of AP morphology and CaT alternans was observed. During CaT alternans application of voltage clamp protocols in form of pre-recorded APs revealed a prominent Ca(2+)-dependent membrane current consisting of a large outward component coinciding with AP phases 1 and 2, followed by an inward current during AP repolarization. Approximately 85% of the initial outward current was blocked by Cl(-) channel blocker DIDS or lowering external Cl(-) concentration identifying it as a Ca(2+)-activated Cl(-) current (ICaCC). The data suggest that ICaCC plays a critical role in shaping beat-to-beat alternations in AP morphology during alternans.

  17. Impaired beta-adrenergic response and decreased L-type calcium current of hypertrophied left ventricular myocytes in postinfarction heart failure

    Directory of Open Access Journals (Sweden)

    R.M. Saraiva

    2003-05-01

    Full Text Available Infarct-induced heart failure is usually associated with cardiac hypertrophy and decreased ß-adrenergic responsiveness. However, conflicting results have been reported concerning the density of L-type calcium current (I Ca(L, and the mechanisms underlying the decreased ß-adrenergic inotropic response. We determined I Ca(L density, cytoplasmic calcium ([Ca2+]i transients, and the effects of ß-adrenergic stimulation (isoproterenol in a model of postinfarction heart failure in rats. Left ventricular myocytes were obtained by enzymatic digestion 8-10 weeks after infarction. Electrophysiological recordings were obtained using the patch-clamp technique. [Ca2+]i transients were investigated via fura-2 fluorescence. ß-Adrenergic receptor density was determined by [³H]-dihydroalprenolol binding to left ventricle homogenates. Postinfarction myocytes showed a significant 25% reduction in mean I Ca(L density (5.7 ± 0.28 vs 7.6 ± 0.32 pA/pF and a 19% reduction in mean peak [Ca2+]i transients (0.13 ± 0.007 vs 0.16 ± 0.009 compared to sham myocytes. The isoproterenol-stimulated increase in I Ca(L was significantly smaller in postinfarction myocytes (Emax: 63.6 ± 4.3 vs 123.3 ± 0.9% in sham myocytes, but EC50 was not altered. The isoproterenol-stimulated peak amplitude of [Ca2+]i transients was also blunted in postinfarction myocytes. Adenylate cyclase activation through forskolin produced similar I Ca(L increases in both groups. ß-Adrenergic receptor density was significantly reduced in homogenates from infarcted hearts (Bmax: 93.89 ± 20.22 vs 271.5 ± 31.43 fmol/mg protein in sham myocytes, while Kd values were similar. We conclude that postinfarction myocytes from large infarcts display reduced I Ca(L density and peak [Ca2+]i transients. The response to ß-adrenergic stimulation was also reduced and was probably related to ß-adrenergic receptor down-regulation and not to changes in adenylate cyclase activity.

  18. Illuminating Myocyte-Fibroblast Homotypic and Heterotypic Gap Junction Dynamics Using Dynamic Clamp.

    Science.gov (United States)

    Brown, Tashalee R; Krogh-Madsen, Trine; Christini, David J

    2016-08-23

    Fibroblasts play a significant role in the development of electrical and mechanical dysfunction of the heart; however, the underlying mechanisms are only partially understood. One widely studied mechanism suggests that fibroblasts produce excess extracellular matrix, resulting in collagenous septa that slow propagation, cause zig-zag conduction paths, and decouple cardiomyocytes, resulting in a substrate for cardiac arrhythmia. An emerging mechanism suggests that fibroblasts promote arrhythmogenesis through direct electrical interactions with cardiomyocytes via gap junction (GJ) channels. In the heart, three major connexin (Cx) isoforms, Cx40, Cx43, and Cx45, form GJ channels in cell-type-specific combinations. Because each Cx is characterized by a unique time- and transjunctional voltage-dependent profile, we investigated whether the electrophysiological contributions of fibroblasts would vary with the specific composition of the myocyte-fibroblast (M-F) GJ channel. Due to the challenges of systematically modifying Cxs in vitro, we coupled native cardiomyocytes with in silico fibroblast and GJ channel electrophysiology models using the dynamic-clamp technique. We found that there is a reduction in the early peak of the junctional current during the upstroke of the action potential (AP) due to GJ channel gating. However, effects on the cardiomyocyte AP morphology were similar regardless of the specific type of GJ channel (homotypic Cx43 and Cx45, and heterotypic Cx43/Cx45 and Cx45/Cx43). To illuminate effects at the tissue level, we performed multiscale simulations of M-F coupling. First, we developed a cell-specific model of our dynamic-clamp experiments and investigated changes in the underlying membrane currents during M-F coupling. Second, we performed two-dimensional tissue sheet simulations of cardiac fibrosis and incorporated GJ channels in a cell type-specific manner. We determined that although GJ channel gating reduces junctional current, it does not

  19. Myomaker mediates fusion of fast myocytes in zebrafish embryos

    Energy Technology Data Exchange (ETDEWEB)

    Landemaine, Aurélie; Rescan, Pierre-Yves; Gabillard, Jean-Charles, E-mail: Jean-charles.gabillard@rennes.inra.fr

    2014-09-05

    Highlights: • Myomaker is transiently expressed in fast myocytes during embryonic myogenesis. • Myomaker is essential for fast myocyte fusion in zebrafish. • The function of myomaker is conserved among Teleostomi. - Abstract: Myomaker (also called Tmem8c), a new membrane activator of myocyte fusion was recently discovered in mice. Using whole mount in situ hybridization on zebrafish embryos at different stages of embryonic development, we show that myomaker is transiently expressed in fast myocytes forming the bulk of zebrafish myotome. Zebrafish embryos injected with morpholino targeted against myomaker were alive after yolk resorption and appeared morphologically normal, but they were unable to swim, even under effect of a tactile stimulation. Confocal observations showed a marked phenotype characterized by the persistence of mononucleated muscle cells in the fast myotome at developmental stages where these cells normally fuse to form multinucleated myotubes. This indicates that myomaker is essential for myocyte fusion in zebrafish. Thus, there is an evolutionary conservation of myomaker expression and function among Teleostomi.

  20. Dynamic investigation of Drosophila myocytes with second harmonic generation microscopy

    Science.gov (United States)

    Greenhalgh, Catherine; Stewart, Bryan; Cisek, Richard; Prent, Nicole; Major, Arkady; Barzda, Virginijus

    2006-09-01

    The functional dynamics and structure of both larval and adult Drosophila melanogaster muscle were investigated with a nonlinear multimodal microscope. Imaging was carried out using a home built microscope capable of recording the multiphoton excitation fluorescence, second harmonic generation, and third harmonic generation signals simultaneously at a scanning rate of up to ~12 frames/sec. The sample was excited by a home built femtosecond Ti:Sapphire laser at 840 nm, or by a Yb-ion doped potassium gadolinium tungstate (Yb:KGW) crystal based oscillator at 1042 nm. There was no observable damage detected in the myocyte after prolonged scanning with either of the lasers. Microscopic second harmonic generation (SHG) appears particularly strong in the myocytes. This allows the fast contraction dynamics of the myocytes to be followed. The larger sarcomere size observed in the larvae myocytes is especially well suited for studying the contraction dynamics. Microscopic imaging of muscle contractions showed different relaxation and contraction rates. The SHG intensities were significantly higher in the relaxed state of the myocyte compared to the contracted state. The imaging also revealed disappearance of SHG signal in highly stretched sarcomeres, indicating that SHG diminishes in the disordered structures. The study illustrates that SHG microscopy, combined with other nonlinear contrast mechanisms, can help to elucidate physiological mechanisms of contraction. This study also provides further insight into the mechanisms of harmonic generation in biological tissue and shows that crystalline arrangement of macromolecules has a determining factor for the high efficiency second harmonic generation from the bulk structures.

  1. Downstream resource utilization following hybrid cardiac imaging with an integrated cadmium-zinc-telluride/64-slice CT device

    Energy Technology Data Exchange (ETDEWEB)

    Fiechter, Michael; Kaufmann, Philipp A. [University Hospital Zurich, Department of Radiology, Cardiac Imaging, Zurich (Switzerland); University of Zurich, Zurich Center for Integrative Human Physiology (ZIHP), Zurich (Switzerland); Ghadri, Jelena R.; Wolfrum, Mathias; Kuest, Silke M.; Pazhenkottil, Aju P.; Nkoulou, Rene N.; Herzog, Bernhard A.; Gebhard, Catherine; Fuchs, Tobias A.; Gaemperli, Oliver [University Hospital Zurich, Department of Radiology, Cardiac Imaging, Zurich (Switzerland)

    2012-03-15

    Low yield of invasive coronary angiography and unnecessary coronary interventions have been identified as key cost drivers in cardiology for evaluation of coronary artery disease (CAD). This has fuelled the search for noninvasive techniques providing comprehensive functional and anatomical information on coronary lesions. We have evaluated the impact of implementation of a novel hybrid cadmium-zinc-telluride (CZT)/64-slice CT camera into the daily clinical routine on downstream resource utilization. Sixty-two patients with known or suspected CAD were referred for same-day single-session hybrid evaluation with CZT myocardial perfusion imaging (MPI) and coronary CT angiography (CCTA). Hybrid MPI/CCTA images from the integrated CZT/CT camera served for decision-making towards conservative versus invasive management. Based on the hybrid images patients were classified into those with and those without matched findings. Matched findings were defined as the combination of MPI defect with a stenosis by CCTA in the coronary artery subtending the respective territory. All patients with normal MPI and CCTA as well as those with isolated MPI or CCTA finding or combined but unmatched findings were categorized as ''no match''. All 23 patients with a matched finding underwent invasive coronary angiography and 21 (91%) were revascularized. Of the 39 patients with no match, 5 (13%, p < 0.001 vs matched) underwent catheterization and 3 (8%, p < 0.001 vs matched) were revascularized. Cardiac hybrid imaging in CAD evaluation has a profound impact on patient management and may contribute to optimal downstream resource utilization. (orig.)

  2. Swimming training increases cardiac vagal activity and induces cardiac hypertrophy in rats

    Directory of Open Access Journals (Sweden)

    A. Medeiros

    2004-12-01

    Full Text Available The effect of swimming training (ST on vagal and sympathetic cardiac effects was investigated in sedentary (S, N = 12 and trained (T, N = 12 male Wistar rats (200-220 g. ST consisted of 60-min swimming sessions 5 days/week for 8 weeks, with a 5% body weight load attached to the tail. The effect of the autonomic nervous system in generating training-induced resting bradycardia (RB was examined indirectly after cardiac muscarinic and adrenergic receptor blockade. Cardiac hypertrophy was evaluated by cardiac weight and myocyte morphometry. Plasma catecholamine concentrations and citrate synthase activity in soleus muscle were also determined in both groups. Resting heart rate was significantly reduced in T rats (355 ± 16 vs 330 ± 20 bpm. RB was associated with a significantly increased cardiac vagal effect in T rats (103 ± 25 vs 158 ± 40 bpm, since the sympathetic cardiac effect and intrinsic heart rate were similar for the two groups. Likewise, no significant difference was observed for plasma catecholamine concentrations between S and T rats. In T rats, left ventricle weight (13% and myocyte dimension (21% were significantly increased, suggesting cardiac hypertrophy. Skeletal muscle citrate synthase activity was significantly increased by 52% in T rats, indicating endurance conditioning. These data suggest that RB induced by ST is mainly mediated parasympathetically and differs from other training modes, like running, that seems to mainly decrease intrinsic heart rate in rats. The increased cardiac vagal activity associated with ST is of clinical relevance, since both are related to increased life expectancy and prevention of cardiac events.

  3. Targeted Deletion of MicroRNA-22 Promotes Stress-Induced Cardiac Dilation and Contractile Dysfunction

    Science.gov (United States)

    Gurha, Priyatansh; Abreu-Goodger, Cei; Wang, Tiannan; Ramirez, Maricela O.; Drumond, Ana L.; van Dongen, Stijn; Chen, Yuqing; Bartonicek, Nenad; Enright, Anton J.; Lee, Brendan; Kelm, Robert J.; Reddy, Anilkumar K.; Taffet, George E.; Bradley, Allan; Wehrens, Xander H.; Entman, Mark L.; Rodriguez, Antony

    2012-01-01

    Background Delineating the role of microRNAs (miRNAs) in the posttranscriptional gene regulation offers new insights into how the heart adapts to pathological stress. We developed a knockout of miR-22 in mice and investigated its function in the heart. Methods and Results Here, we show that miR-22–deficient mice are impaired in inotropic and lusitropic response to acute stress by dobutamine. Furthermore, the absence of miR-22 sensitized mice to cardiac decompensation and left ventricular dilation after long-term stimulation by pressure overload. Calcium transient analysis revealed reduced sarcoplasmic reticulum Ca2+ load in association with repressed sarcoplasmic reticulum Ca2+ ATPase activity in mutant myocytes. Genetic ablation of miR-22 also led to a decrease in cardiac expression levels for Serca2a and muscle-restricted genes encoding proteins in the vicinity of the cardiac Z disk/titin cytoskeleton. These phenotypes were attributed in part to inappropriate repression of serum response factor activity in stressed hearts. Global analysis revealed increased expression of the transcriptional/translational repressor purine-rich element binding protein B, a highly conserved miR-22 target implicated in the negative control of muscle expression. Conclusion These data indicate that miR-22 functions as an integrator of Ca2+ homeostasis and myofibrillar protein content during stress in the heart and shed light on the mechanisms that enhance propensity toward heart failure. PMID:22570371

  4. Stroke and cardiac cell death: Two peas in a pod.

    Science.gov (United States)

    Gonzales-Portillo, Chiara; Ishikawa, Hiroto; Shinozuka, Kazutaka; Tajiri, Naoki; Kaneko, Yuji; Borlongan, Cesar V

    2016-03-01

    A close pathological link between stroke brain and heart failure may exist. Here, we discuss relevant laboratory and clinical reports demonstrating neural and cardiac myocyte cell death following ischemic stroke. Although various overlapping risk factors exist between cerebrovascular incidents and cardiac incidents, stroke therapy has largely neglected the cardiac pathological consequences. Recent preclinical stroke studies have implicated an indirect cell death pathway, involving toxic molecules, that originates from the stroke brain and produces cardiac cell death. In concert, previous laboratory reports have revealed a reverse cell death cascade, in that cardiac arrest leads to ischemic cell death in the brain. A deeper understanding of the crosstalk of cell death pathways between stroke and cardiac failure will facilitate the development of novel treatments designed to arrest the global pathology of both diseases thereby improving the clinical outcomes of patients diagnosed with stroke and heart failure.

  5. Measurement of isolated myocyte volume using the Coulter models Z2 and ZM/C256: a comparison of instrument function.

    Science.gov (United States)

    Said, S; Tamura, T; Gerdes, A M

    1998-09-01

    Changes in cardiac structure that depart from normal have generally been termed "remodeling". Assessment of ventricular remodeling at the cellular level should include measurement of myocyte dimensions. A well-established and reliable method to assess myocyte remodeling uses isolated cells and the Coulter Counter/Channelyzer system. The new Coulter Model Z2 has numerous modifications and improvements from the Model Z predecessor(s) interfaced to a pulse-height analyzer (e.g., channelyzer). Improvements of the Model Z2 over older instruments include: (i) elimination of the mercury manometer with accompanying oil-displacement pump; (ii) reduced size and weight; (iii) a higher degree of mechanization and automation; (iv) inclusion of an advanced comprehensive statistical package and (v) a substantial reduction in cost. The purpose of this study was to determine if the newly modified instrument produces the same results as the previous instrument combinations, which were shown to produce reliable cell volume data from irregularly shaped cells such as cardiac myocytes.

  6. Integrative Cardiac Health Project

    Science.gov (United States)

    2013-03-01

    of obesity including weight, BMI and % body fat were reduced by 5%. Additionally, a 5% reduction in waist circumference and a 7% reduction in...Diameter (cm) 24.0 ± 3.8 22.3 ± 3.7 -1.7 ± 1.6 ɘ.0011 Waist Circumference (cm) 100.6 ± 13.1 95.6 ± 13.1 -5.0 ± 4.1 ɘ.0011 13 Baseline Study...mass index (mean± SD ·31.1 ± 5.9 vs. 29.0 ± 5.9, rs = 0.175), increased waist circumference (102 ± 17 em vs. 98 ± 14, rs = 0.135), and elevated high

  7. Integrative Cardiac Health Project

    Science.gov (United States)

    2012-10-01

    conflicts of interest. The authors alone are responsible for the content and writing of the paper. References Basta .M, Ch.rousos GP , Vela-Bueno A... GP , Vela-Bueno A. 2009a. Insomnia witl1 objective short sleep duration is associated with a high risk for hypertension. Sleep 32:491 - 497...eta/. Mindfulness meditation training in adults and adolescents with ADHD : a feasibility study. 1 Atten Disord 2008;11(6):737-46. 17. Segal ZV

  8. Integrative Cardiac Health Project

    Science.gov (United States)

    2014-10-01

    SPSS Survival Manual : A Step by Step Guide to Data Analysis Using the SPSS Program. 4th ed. New York, NY: McGraw-Hill; 2010...with Traumatic Amputations” protocol (PI: Alison Pruziner), DPT, ATC, WRNMMC Dept of Rehab). Status: Task #4: Follow-up data analysis and...that were excluded from further analysis because of significant differences in expression among duplicate samples (Table I in the Data

  9. DNA Damage Response and DNA Repair in Skeletal Myocytes From a Mouse Model of Spinal Muscular Atrophy.

    Science.gov (United States)

    Fayzullina, Saniya; Martin, Lee J

    2016-09-01

    We studied DNA damage response (DDR) and DNA repair capacities of skeletal muscle cells from a mouse model of infantile spinal muscular atrophy (SMA) caused by loss-of-function mutation of survival of motor neuron (Smn). Primary myocyte cultures derived from skeletal muscle satellite cells of neonatal control and mutant SMN mice had similar myotube length, myonuclei, satellite cell marker Pax7 and differentiated myotube marker myosin, and acetylcholine receptor clustering. DNA damage was induced in differentiated skeletal myotubes by γ-irradiation, etoposide, and methyl methanesulfonate (MMS). Unexposed control and SMA myotubes had stable genome integrity. After γ-irradiation and etoposide, myotubes repaired most DNA damage equally. Control and mutant myotubes exposed to MMS exhibited equivalent DNA damage without repair. Control and SMA myotube nuclei contained DDR proteins phospho-p53 and phospho-H2AX foci that, with DNA damage, dispersed and then re-formed similarly after recovery. We conclude that mouse primary satellite cell-derived myotubes effectively respond to and repair DNA strand-breaks, while DNA alkylation repair is underrepresented. Morphological differentiation, genome stability, genome sensor, and DNA strand-break repair potential are preserved in mouse SMA myocytes; thus, reduced SMN does not interfere with myocyte differentiation, genome integrity, and DNA repair, and faulty DNA repair is unlikely pathogenic in SMA.

  10. Cardiac troponins and high-sensitivity cardiac troponin assays.

    Science.gov (United States)

    Conrad, Michael J; Jarolim, Petr

    2014-03-01

    Measurement of circulating cardiac troponins I and T has become integral to the diagnosis of myocardial infarction. This article discusses the structure and function of the troponin complex and the release of cardiac troponin molecules from the injured cardiomyocyte into the circulation. An overview of current cardiac troponin assays and their classification according to sensitivity is presented. The diagnostic criteria, role, and usefulness of cardiac troponin for myocardial infarction are discussed. In addition, several examples are given of the usefulness of high-sensitivity cardiac troponin assays for short-term and long-term prediction of adverse events.

  11. Biomaterials for cardiac regeneration

    CERN Document Server

    Ruel, Marc

    2015-01-01

    This book offers readers a comprehensive biomaterials-based approach to achieving clinically successful, functionally integrated vasculogenesis and myogenesis in the heart. Coverage is multidisciplinary, including the role of extracellular matrices in cardiac development, whole-heart tissue engineering, imaging the mechanisms and effects of biomaterial-based cardiac regeneration, and autologous bioengineered heart valves. Bringing current knowledge together into a single volume, this book provides a compendium to students and new researchers in the field and constitutes a platform to allow for future developments and collaborative approaches in biomaterials-based regenerative medicine, even beyond cardiac applications. This book also: Provides a valuable overview of the engineering of biomaterials for cardiac regeneration, including coverage of combined biomaterials and stem cells, as well as extracellular matrices Presents readers with multidisciplinary coverage of biomaterials for cardiac repair, including ...

  12. Differences of promethazine and terfenadine on ion channels in guinea pig ventricular myocytes

    Institute of Scientific and Technical Information of China (English)

    LI Xue-wen; NIU Shuan-cheng; ZHANG Xuan-ping; L(U) Ji-yuan; BAI Feng; ZHANG Ling; WU Bo-wei

    2006-01-01

    @@ Promethazine, a first generation antihistamine,has an antiarrhythmic effect on ischemia-reperfusion inducing arrhythmias1 and experimental arrhythmias.2 However, terfenadine as a second generation of antihistamine, has been reported to elicit hypotension, bradycardia, prolongation of the QTc interval and torsades de pointes (TdP) like ventricular arrhythmia.3 This may be due to the blockage on rectifier postassium current (Ik) of terfenadine, resulting in the prolongation of the action potential duration (APD) and dispersion of the repolarization duration, which might provoke a specific form of polymorphic ventricular tachydysrhythmia, i.e. TdP.4 In clinical practice,however, the class Ⅲ antiarrhythmic agents, which target on the Ik and prolong the action potential duration and QTc interval, rarely lead to arrhythmias.Other actions must be considered to underlie the arrhythmogenic tendency of terfenadine besides its inhibition on Ik. Though both promethazine and terfenadine block the H1 receptor, there must be a different pharmacology profile between the two compounds on ion channels of cardiac myocytes.Whole-cell patch clamp technique was used to investigate the effects of these two antagonists of the H1 receptor on the main ion currents in cardiac electrical activities.

  13. The Effects of Puerarin on Rat Ventricular Myocytes and the Potential Mechanism

    Science.gov (United States)

    Xu, Hao; Zhao, Manxi; Liang, Shenghui; Huang, Quanshu; Xiao, Yunchuan; Ye, Liang; Wang, Qinyi; He, Longmei; Ma, Lanxiang; Zhang, Hua; Zhang, Li; Jiang, Hui; Ke, Xiao; Gu, Yuchun

    2016-01-01

    Puerarin, a known isoflavone, is commonly found as a Chinese herb medicine. It is widely used in China to treat cardiac diseases such as angina, cardiac infarction and arrhythmia. However, its cardioprotective mechanism remains unclear. In this study, puerarin significantly prolonged ventricular action potential duration (APD) with a dosage dependent manner in the micromolar range on isolated rat ventricular myocytes. However, submicromolar puerarin had no effect on resting membrane potential (RMP), action potential amplitude (APA) and maximal velocity of depolarization (Vmax) of action potential. Only above the concentration of 10 mM, puerarin exhibited more aggressive effect on action potential, and shifted RMP to the positive direction. Millimolar concentrations of puerarin significantly inhibited inward rectified K+ channels in a dosage dependent manner, and exhibited bigger effects upon Kir2.1 vs Kir2.3 in transfected HEK293 cells. As low as micromolar range concentrations of puerarin significantly inhibited Kv7.1 and IKs. These inhibitory effects may due to the direct inhibition of puerarin upon channels not via the PKA-dependent pathway. These results provided direct preclinical evidence that puerarin prolonged APD via its inhibitory effect upon Kv7.1 and IKs, contributing to a better understanding the mechanism of puerarin cardioprotection in the treatment of cardiovascular diseases. PMID:27762288

  14. Isorhamnetin protects rat ventricular myocytes from ischemia and reperfusion injury.

    Science.gov (United States)

    Zhang, Najuan; Pei, Fei; Wei, Huaying; Zhang, Tongtong; Yang, Chao; Ma, Gang; Yang, Chunlei

    2011-01-01

    Ischemia/reperfusion (I/R) has been known to cause damages to ventricular myocytes. Isorhamnetin, one member of flavonoid compounds, has cardioprotective effect, the effect that suggests a possible treatment for I/R damages. In the present investigation, we found that isorhamnetin could significantly promote the viability of neonatal rat ventricular myocytes that were exposed to ischemia/reperfusion (I/R) in vitro. Ventricular myocytes were obtained from neonatal SD rats, and then were divided randomly into three groups, namely I/R-/isor-, I/R+/isor- and I/R+/isor+ group. Before the whole experiment, the most appropriate concentration of isorhamnetin (4 μM) was determined by MTT assay. Our results showed that isorhamnetin could alleviate the damages of I/R to ventricular myocytes through inhibiting lactate dehydrogenase (LDH) activity, and repressing apoptosis. Compared with the counterpart of the I/R+/isor- group, LDH activity in the isorhamnetin-treated group weakened, halving from 24.1 ± 2.3 to 11.4 ± 1.2U/L. Additionally, flow cytometry showed the apparently increased apoptosis rate induced by I/R, the result that was further confirmed by transmission electron microscope. Administration of isorhamnetin, however, assuaged the apoptosis induced by I/R. Corresponding to the reduced apoptosis rate in the I/R+/isor+ group, western blotting assay showed increased amount of Bcl-2 and p53, decreased amount of Bax, and nuclear accumulation of NF-κB/p65.

  15. Xanthohumol Modulates Calcium Signaling in Rat Ventricular Myocytes: Possible Antiarrhythmic Properties.

    Science.gov (United States)

    Arnaiz-Cot, Juan Jose; Cleemann, Lars; Morad, Martin

    2017-01-01

    Cardiac arrhythmia is a major cause of mortality in cardiovascular pathologies. A host of drugs targeted to sarcolemmal Na(+), Ca(2+), and K(+) channels has had limited success clinically. Recently, Ca(2+) signaling has been target of pharmacotherapy based on finding that leaky ryanodine receptors elevate local Ca(2+) concentrations causing membrane depolarizations that trigger arrhythmias. In this study, we report that xanthohumol, an antioxidant extracted from hops showing therapeutic effects in other pathologies, suppresses aberrant ryanodine receptor Ca(2+) release. The effects of xanthohumol (5-1000 nM) on Ca(2+) signaling pathways were probed in isolated rat ventricular myocytes incubated with Fluo-4 AM using the perforated patch-clamp technique. We found that 5-50 nM xanthohumol reduced the frequency of spontaneously occurring Ca(2+) sparks (>threefold) and Ca(2+) waves in control myocytes and in cells subjected to Ca(2+) overload caused by the following: 1) exposure to low K(+) solutions, 2) periods of high frequency electrical stimulation, 3) exposures to isoproterenol, or 4) caffeine. At room temperatures, 50-100 nM xanthohumol reduced the rate of relaxation of electrically- or caffeine-triggered Ca(2+)transients, without suppressing ICa, but this effect was small and reversed by isoproterenol at physiologic temperatures. Xanthohumol also suppressed the Ca(2+) content of the SR and its rate of recirculation. The stabilizing effects of xanthohumol on the frequency of spontaneously triggered Ca(2+) sparks and waves combined with its antioxidant properties, and lack of significant effects on Na(+) and Ca(2+) channels, may provide this compound with clinically desirable antiarrhythmic properties.

  16. An integrative view of cisplatin-induced renal and cardiac toxicities : Molecular mechanisms, current treatment challenges and potential protective measures

    NARCIS (Netherlands)

    Dugbartey, George J; Peppone, Luke J; de Graaf, Inge A M

    2016-01-01

    Cisplatin is currently one of the most widely-used chemotherapeutic agents against various malignancies. Its clinical application is limited, however, by inherent renal and cardiac toxicities and other side effects, of which the underlying mechanisms are only partly understood. Experimental studies

  17. Characterization of signalling pathways in cardiac hypertrophic response

    OpenAIRE

    2011-01-01

    Abstract Intracellular signalling cascades regulate cardiomyocyte hypertrophic response. Initially hypertrophy of individual myocytes occurs as an adaptive response to increased demands for cardiac work, e.g. during hypertension or after myocardial infarction, but a prolonged hypertrophic response, accompanied by accelerated fibrosis and apoptosis, predisposes the heart to impaired performance and the syndrome of heart failure. The goal of this work was to elucidate some of the main sig...

  18. Micro and Nano-mediated 3D Cardiac Tissue Engineering

    Science.gov (United States)

    2009-10-01

    13-70% positive for CD34, similar to values and ranges found for both excised and liposuction derived human cells. Also similar to human cells... position , policy or decision unless so designated by other documentation. REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public...studies. We examined the effects of substrate stiffness on the beating rate and beating force in embryonic chicken cardiac myocytes. Our results

  19. Negative inotropic effect of a CB2 agonist A-955840 in isolated rabbit ventricular myocytes is independent of CB1 and CB2 receptors.

    Science.gov (United States)

    Su, Zhi; Preusser, Lee; Diaz, Gilbert; Green, Jonathon; Liu, Xiaoqin; Polakowski, James; Dart, Michael; Yao, Betty; Meyer, Michael; Limberis, James T; Martin, Ruth L; Cox, Bryan F; Gintant, Gary A

    2011-11-01

    A-955840, a selective CB2 agonist, has been shown to elicit concentration-dependent decreases in cardiac contractility in the anesthetized dog (decreased maximal velocity of left ventricular pressure development [LV dP/dt max]). However, it is unknown whether this represents a direct effect or a response dependent on other factors (such as autonomic tone and neurohumoral factors) present in vivo. This study examined if A-955840 had a direct effect on contractility of isolated cardiac myocytes, and if so to determine the potential mechanisms. Contractility was assessed in vitro using percent changes in maximal shortening velocity of sarcomeres (dL/dt max) and fractional shortening of sarcomere length (FS) in rabbit left ventricular myocytes. L-type calcium current in myocytes was recorded using wholecell voltage-clamp techniques. A-955840 reduced dL/dt max and FS in a reversible and concentration-dependent manner with an IC50 of 11.4 μg/mL (based on dL/dt max) which is similar to the estimated IC50 value of 9.8 μg/mL based on the effects of A-955840 on LV dP/dt max in anesthetized dogs. A-955840 (4.1 μg/mL) reduced myocyte contractility (%FS) to a similar extent in the absence and presence of a CB2 antagonist, SR-2 (24.0 ± 3.4 vs 23.1 ± 3.0 %, n=5) or a CB1 antagonist, Rimonabant (18.8 ± 2.3 vs 19.8 ± 2.7 %, n=5). A-955840 (4.1 μg/mL) also reduced L-type calcium current of rabbit ventricular myocytes (1.05 ± 0.11 vs 0.70 ± 0.12 nA, n=5, P CB2 nor CB1 receptors, and consistent with off-target negative inotropy mediated by inhibition of the cardiac L-type calcium current.

  20. Paracrine Engineering of Human Explant-Derived Cardiac Stem Cells to Over-Express Stromal-Cell Derived Factor 1α Enhances Myocardial Repair.

    Science.gov (United States)

    Tilokee, Everad L; Latham, Nicholas; Jackson, Robyn; Mayfield, Audrey E; Ye, Bin; Mount, Seth; Lam, Buu-Khanh; Suuronen, Erik J; Ruel, Marc; Stewart, Duncan J; Davis, Darryl R

    2016-07-01

    First generation cardiac stem cell products provide indirect cardiac repair but variably produce key cardioprotective cytokines, such as stromal-cell derived factor 1α, which opens the prospect of maximizing up-front paracrine-mediated repair. The mesenchymal subpopulation within explant derived human cardiac stem cells underwent lentiviral mediated gene transfer of stromal-cell derived factor 1α. Unlike previous unsuccessful attempts to increase efficacy by boosting the paracrine signature of cardiac stem cells, cytokine profiling revealed that stromal-cell derived factor 1α over-expression prevented lv-mediated "loss of cytokines" through autocrine stimulation of CXCR4+ cardiac stem cells. Stromal-cell derived factor 1α enhanced angiogenesis and stem cell recruitment while priming cardiac stem cells to readily adopt a cardiac identity. As compared to injection with unmodified cardiac stem cells, transplant of stromal-cell derived factor 1α enhanced cells into immunodeficient mice improved myocardial function and angiogenesis while reducing scarring. Increases in myocardial stromal-cell derived factor 1α content paralleled reductions in myocyte apoptosis but did not influence long-term engraftment or the fate of transplanted cells. Transplantation of stromal-cell derived factor 1α transduced cardiac stem cells increased the generation of new myocytes, recruitment of bone marrow cells, new myocyte/vessel formation and the salvage of reversibly damaged myocardium to enhance cardiac repair after experimental infarction. Stem Cells 2016;34:1826-1835.

  1. Berberine alleviates cardiac ischemia/reperfusion injury by inhibiting excessive autophagy in cardiomyocytes.

    Science.gov (United States)

    Huang, Zhouqing; Han, Zhihua; Ye, Bozhi; Dai, Zhenyu; Shan, Peiren; Lu, Zhongqiu; Dai, Kezhi; Wang, Changqian; Huang, Weijian

    2015-09-05

    Ischemia/reperfusion (I/R)-induced autophagy increases the severity of cardiomyocyte injury. The aim of this study was to investigate the effects of berberine, a natural extract from Rhizoma coptidis, on the I/R-induced excessive autophagy in in vitro and in vivo models. Autophagy was increased both in H9c2 myocytes during hypoxia/reoxygenation (H/R) injury and in mouse hearts exposed to I/R. And the expression level of p-AMPK and p-mTORC2 (Ser2481) were increased during H/R period. In addition, the increased autophagy level was correlated with reduced cell survival in H9c2 myocytes and increased infarct size in mouse hearts. However, berberine treatment significantly enhanced the H/R-induced cell viability and reduced I/R-induced myocardial infarct size, which was accompanied by improved cardiac function. The beneficial effect of berberine is associated with inhibiting the cellular autophagy level, due to decreasing the expression level of autophagy-related proteins such as SIRT1, BNIP3, and Beclin-1. Furthermore, both the level of p-AMPK and p-mTORC2 (Ser2481) in H9c2 myocytes exposed to H/R were decreased by berberine. In summary, berberine protects myocytes during I/R injury through suppressing autophagy activation. Therefore, berberine may be a promising agent for treating I/R-induced cardiac myocyte injury.

  2. Cardiac arrest

    Science.gov (United States)

    ... Article.jsp. Accessed June 16, 2014. Myerburg RJ, Castellanos A. Approach to cardiac arrest and life-threatening ... PA: Elsevier Saunders; 2011:chap 63. Myerburg RJ, Castellanos A. Cardiac arrest and audden aardiac death. In: ...

  3. Urocortin2 prolongs action potential duration and modulates potassium currents in guinea pig myocytes and HEK293 cells.

    Science.gov (United States)

    Yang, Li-Zhen; Zhu, Yi-Chun

    2015-07-01

    We previously reported that activation of corticotropin releasing factor receptor type 2 by urocortin2 up-regulates both L-type Ca(2+) channels and intracellular Ca(2+) concentration in ventricular myocytes and plays an important role in cardiac contractility and arrhythmogenesis. This study goal was to further test the hypothesis that urocortin2 may modulate action potentials as well as rapidly and slowly activating delayed rectifier potassium currents. With whole cell patch-clamp techniques, action potentials and slowly activating delayed rectifier potassium currents were recorded in isolated guinea pig ventricular myocytes, respectively. And rapidly activating delayed rectifier potassium currents were tested in hERG-HEK293 cells. Urocortin2 produced a time- and concentration-dependent prolongation of action potential duration. The EC50 values of action potential duration and action potential duration at 90% of repolarization were 14.73 and 24.3nM respectively. The prolongation of action potential duration of urocortin2 was almost completely or partly abolished by H-89 (protein kinase A inhibitor) or KB-R7943 (Na(+)/Ca(2+) exchange inhibitor) pretreatment respectively. And urocortin2 caused reduction of rapidly activating delayed rectifier potassium currents in hERG-HEK293 cells. In addition, urocortin2 slowed the rate of slowly activating delayed rectifier potassium channel activation, and rightward shifted the threshold of slowly activating delayed rectifier potassium currents to more positive potentials. Urocortin2 prolonged action potential duration via activation of protein kinase A and Na(+)/ Ca(2+) exchange in isolated guinea pig ventricular myocytes in a time- and concentration- dependent manner. In hERG-HEK293 cells, urocortin2 reduced rapidly activating delayed rectifier potassium current density which may contribute to action potential duration prolongation.

  4. Electrophysiological effects of Chinese medicine Shen song Yang xin (SSYX) on Chinese miniature swine heart and isolated guinea pig ventricular myocytes

    Institute of Scientific and Technical Information of China (English)

    FENG Li; GONG Jing; JIN Zhen-yi; LI Ning; SUN Li-ping; WU Yi-ling; PU Jie-lin

    2009-01-01

    Background Shen song Yang xin (SSYX) is a compound of Chinese medicine with the effect of increasing heart rate (HR). This study aimed to evaluate its electrophysiological properties at heart and cellular levels. Methods The Chinese miniature swines were randomly assigned to two groups, administered with SSYX or placebo for 4 weeks (n=8 per group). Cardiac electrophysiological study (EPS) was performed before and after drug administration. The guinea pig ventricular myocytes were enzymatically isolated and whole cell voltage-clamp technique was used to evaluate the effect of SSYX on cardiac action potential (AP). Results SSYX treatment accelerated the HR from (141.8±36.0) beats per minute to (163.0±38.0) beats per minute (P=0.013) without changing the other parameters in surface electrocardiogram. After blockage of the autonomic nervous system with metoprolol and atropin, SSYX had no effect on intrinsic HR (IHR), but decreased corrected sinus node recovery time (CSNRT) and sinus atrium conducting time (SACT). Intra cardiac EPS showed that SSYX significantly decreased the A-H and A-V intervals as well as shortened the atrial (A), atrioventricular node (AVN) and ventricular (V) effective refractory period (ERP). In isolated guinea pig ventricular myocytes, the most obvious effect of SSYX on action potential was a shortening of the action potential duration (APD) without change in shape of action potential. The shortening rates of APD30, APD50 and APDgo were 19.5%, 17.8% and 15.3%, respectively. The resting potential (Em) and the interval between the end of APD3o and APD9o did not significantly change.Conclusions The present study demonstrates that SSYX increases the HR and enhances the conducting capacity of the heart in the condition of the intact autonomic nervous system. SSYX homogenously decreases the ERP of the heart and shortens the APD of the myocytes, suggesting its antiarrhythmic effect without proarrhythmia.

  5. Extracellular high-mobility group box 1 mediates pressure overload-induced cardiac hypertrophy and heart failure.

    Science.gov (United States)

    Zhang, Lei; Liu, Ming; Jiang, Hong; Yu, Ying; Yu, Peng; Tong, Rui; Wu, Jian; Zhang, Shuning; Yao, Kang; Zou, Yunzeng; Ge, Junbo

    2016-03-01

    Inflammation plays a key role in pressure overload-induced cardiac hypertrophy and heart failure, but the mechanisms have not been fully elucidated. High-mobility group box 1 (HMGB1), which is increased in myocardium under pressure overload, may be involved in pressure overload-induced cardiac injury. The objectives of this study are to determine the role of HMGB1 in cardiac hypertrophy and cardiac dysfunction under pressure overload. Pressure overload was imposed on the heart of male wild-type mice by transverse aortic constriction (TAC), while recombinant HMGB1, HMGB1 box A (a competitive antagonist of HMGB1) or PBS was injected into the LV wall. Moreover, cardiac myocytes were cultured and given sustained mechanical stress. Transthoracic echocardiography was performed after the operation and sections for histological analyses were generated from paraffin-embedded hearts. Relevant proteins and genes were detected. Cardiac HMGB1 expression was increased after TAC, which was accompanied by its translocation from nucleus to both cytoplasm and intercellular space. Exogenous HMGB1 aggravated TAC-induced cardiac hypertrophy and cardiac dysfunction, as demonstrated by echocardiographic analyses, histological analyses and foetal cardiac genes detection. Nevertheless, the aforementioned pathological change induced by TAC could partially be reversed by HMGB1 inhibition. Consistent with the in vivo observations, mechanical stress evoked the release and synthesis of HMGB1 in cultured cardiac myocytes. This study indicates that the activated and up-regulated HMGB1 in myocardium, which might partially be derived from cardiac myocytes under pressure overload, may be of crucial importance in pressure overload-induced cardiac hypertrophy and cardiac dysfunction.

  6. Vasopressin Type 1A Receptor Deletion Enhances Cardiac Contractility, β-Adrenergic Receptor Sensitivity and Acute Cardiac Injury-induced Dysfunction.

    Science.gov (United States)

    Wasilewski, Melissa A; Grisanti, Laurel A; Song, Jianliang; Carter, Rhonda L; Repas, Ashley A; Myers, Valerie D; Gao, Erhe; Koch, Walter J; Cheung, Joseph Y; Feldman, Arthur M; Tilley, Douglas

    2016-09-02

    V1AR expression is elevated in chronic human heart failure and contributes to cardiac dysfunction in animal models, in part via reduced βAR responsiveness.  While cardiac V1AR overexpression and V1AR stimulation are each sufficient to decrease βAR activity, it is unknown whether V1AR inhibition conversely augments βAR responsiveness.  Further, although V1AR has been shown to contribute to chronic progression of heart failure, its impact on cardiac function following acute ischemic injury has not been reported.  Using V1AR KO mice we assessed the impact of V1AR deletion on cardiac contractility at baseline and following ischemic injury, βAR sensitivity and cardiomyocyte responsiveness to βAR stimulation.  Strikingly, baseline cardiac contractility was enhanced in V1AR KO mice and they experienced a greater loss in contractile function than control mice following acute ischemic injury, although the absolute levels of cardiac dysfunction and survival rates did not differ.  Enhanced cardiac contractility in V1AR KO mice was associated with augmented β-blocker sensitivity, suggesting increased basal βAR activity, and indeed levels of left ventricular cAMP, as well as phospholamban and cardiac troponin I phosphorylation were elevated versus control mice.  At the cellular level, myocytes isolated from V1AR KO mice demonstrated increased responsiveness to βAR stimulation consistent with the finding that acute pharmacological V1AR inhibition enhanced βAR-mediated contractility in control myocytes.  Therefore, while V1AR deletion does not protect the heart from the rapid development of cardiac dysfunction following acute ischemic injury, its effects on βAR activity suggest that acute V1AR inhibition could be utilized to promote myocyte contractile performance.

  7. Dynamic Changes in Sarcoplasmic Reticulum Structure in Ventricular Myocytes

    Directory of Open Access Journals (Sweden)

    Amanda L. Vega

    2011-01-01

    sarcoplasmic reticulum (SR and the sarcolemma where Ca2+ release is activated. Here, we tested the hypothesis that the SR is a structurally inert organelle in ventricular myocytes. Our data suggest that rather than being static, the SR undergoes frequent dynamic structural changes. SR boutons expressing functional ryanodine receptors moved throughout the cell, approaching or moving away from the sarcolemma of ventricular myocytes. These changes in SR structure occurred in the absence of changes in [Ca2+] during EC coupling. Microtubules and the molecular motors dynein and kinesin 1(Kif5b were important regulators of SR motility. These findings support a model in which the SR is a motile organelle capable of molecular motor protein-driven structural changes.

  8. Nanoscale three-dimensional imaging of the human myocyte.

    Science.gov (United States)

    Sulkin, Matthew S; Yang, Fei; Holzem, Katherine M; Van Leer, Brandon; Bugge, Cliff; Laughner, Jacob I; Green, Karen; Efimov, Igor R

    2014-10-01

    The ventricular human myocyte is spatially organized for optimal ATP and Ca(2+) delivery to sarcomeric myosin and ionic pumps during every excitation-contraction cycle. Comprehension of three-dimensional geometry of the tightly packed ultrastructure has been derived from discontinuous two-dimensional images, but has never been precisely reconstructed or analyzed in human myocardium. Using a focused ion beam scanning electron microscope, we created nanoscale resolution serial images to quantify the three-dimensional ultrastructure of a human left ventricular myocyte. Transverse tubules (t-tubule), lipid droplets, A-bands, and mitochondria occupy 1.8, 1.9, 10.8, and 27.9% of the myocyte volume, respectively. The complex t-tubule system has a small tortuosity (1.04±0.01), and is composed of long transverse segments with diameters of 317±24nm and short branches. Our data indicates that lipid droplets located well beneath the sarcolemma are proximal to t-tubules, where 59% (13 of 22) of lipid droplet centroids are within 0.50μm of a t-tubule. This spatial association could have an important implication in the development and treatment of heart failure because it connects two independently known pathophysiological alterations, a substrate switch from fatty acids to glucose and t-tubular derangement.

  9. A unified theory of calcium alternans in ventricular myocytes

    Science.gov (United States)

    Qu, Zhilin; Liu, Michael B.; Nivala, Michael

    2016-01-01

    Intracellular calcium (Ca2+) alternans is a dynamical phenomenon in ventricular myocytes, which is linked to the genesis of lethal arrhythmias. Iterated map models of intracellular Ca2+ cycling dynamics in ventricular myocytes under periodic pacing have been developed to study the mechanisms of Ca2+ alternans. Two mechanisms of Ca2+ alternans have been demonstrated in these models: one relies mainly on fractional sarcoplasmic reticulum Ca2+ release and uptake, and the other on refractoriness and other properties of Ca2+ sparks. Each of the two mechanisms can partially explain the experimental observations, but both have their inconsistencies with the experimental results. Here we developed an iterated map model that is composed of two coupled iterated maps, which unifies the two mechanisms into a single cohesive mathematical framework. The unified theory can consistently explain the seemingly contradictory experimental observations and shows that the two mechanisms work synergistically to promote Ca2+ alternans. Predictions of the theory were examined in a physiologically-detailed spatial Ca2+ cycling model of ventricular myocytes. PMID:27762397

  10. Uso de fluorescência em um método de dissector modificado para estimar o número de miócitos no tecido cardíaco Uso de fluorescencia en un método de disector modificado para estimar el número de miocitos en el tejido cardíaco Use of fluorescence in a modified disector method to estimate the number of myocytes in cardiac tissue

    Directory of Open Access Journals (Sweden)

    Rômulo Dias Novaes

    2012-03-01

    rea de 3D. OBJETIVO: Usar la microscopia de fluorescencia en un método de disector modificado para determinar el número de miocitos en el tejido cardíaco en condiciones normales y patológicas. MÉTODOS: El estudio empleó ratones Wistar machos de cuatro meses de edad y peso de 366,25 ± 88,21 g randomizados en grupos controles (GC, n = 8 e infectados (GI, n = 8. Los animales del GI fueron inoculados con cepa Y de T. cruzi (300.000 tripomastigotas/50 g. Después de ocho semanas, los animales fueron pesados y sacrificados. Los Ventrículos Izquierdos (VI fueron removidos para análisis estereológico de la densidad numérica de cardiomiocitos (Nv [c] y el número total de esas células en el VI (N [c]. Esos parámetros fueron estimados usando un disector fluorescente (FD y comparados con los métodos convencionales de disector óptico (OD y disector físico (PD. RESULTADOS: En ambos métodos de disector, los animales del GI presentaron caída significativa de Nv[c] y N[c] en comparación con los animales del GC (P > 0,05. Una correlación fuerte, igual o superior a 96%, fue obtenida entre FD, OD y PD. CONCLUSIÓN: El método FD parece ser igualmente confiable para determinar Nv[c] y N[c] en condiciones normales y patológicas, presentando algunas ventajas en relación a los métodos convencionales de disector: reducción de cortes histológicos e imágenes en el análisis estereológico, reducción del tiempo de análisis de las imágenes, la construcción de FD en microscopios simples, utilizando el modo de epifluorescencia, distinción de planos de disector en ampliaciones inferiores.BACKGROUND: Conventional disector methods currently require considerable financial, technical and operational costs to estimate the number of cells, including cardyomyocytes, in a 3D area. OBJECTIVE: To use fluorescence microscopy in a modified disector method to determine the number of myocytes in cardiac tissue in normal and pathological conditions. METHODS: The study employed four

  11. SR-targeted CaMKII inhibition improves SR Ca2+ handling, but accelerates cardiac remodeling in mice overexpressing CaMKIIδC

    OpenAIRE

    Huke, Sabine; DeSantiago, Jaime; Kaetzel, Marcia A.; Mishra, Shikha; Brown, Joan H.; Dedman, John R.; Bers, Donald M.

    2010-01-01

    Cardiac myocyte overexpression of CaMKIIδC leads to cardiac hypertrophy and heart failure (HF) possibly caused by altered myocyte Ca2+ handling. A central defect might be the marked CaMKII-induced increase in diastolic sarcoplasmic reticulum (SR) Ca2+ leak which decreases SR Ca2+ load and Ca2+ transient amplitude. We hypothesized that inhibition of CaMKII near the SR membrane would decrease the leak, improve Ca2+ handling and prevent the development of contractile dysfunction and HF. To test ...

  12. Calcium release near L-type calcium channels promotes beat-to-beat variability in ventricular myocytes from the chronic AV block dog.

    Science.gov (United States)

    Antoons, Gudrun; Johnson, Daniel M; Dries, Eef; Santiago, Demetrio J; Ozdemir, Semir; Lenaerts, Ilse; Beekman, Jet D M; Houtman, Marien J C; Sipido, Karin R; Vos, Marc A

    2015-12-01

    Beat-to-beat variability of ventricular repolarization (BVR) has been proposed as a strong predictor of Torsades de Pointes (TdP). BVR is also observed at the myocyte level, and a number of studies have shown the importance of calcium handling in influencing this parameter. The chronic AV block (CAVB) dog is a model of TdP arrhythmia in cardiac hypertrophy, and myocytes from these animals show extensive remodeling, including of Ca(2+) handling. This remodeling process also leads to increased BVR. We aimed to determine the role that (local) Ca(2+) handling plays in BVR. In isolated LV myocytes an exponential relationship was observed between BVR magnitude and action potential duration (APD) at baseline. Inhibition of Ca(2+) release from sarcoplasmic reticulum (SR) with thapsigargin resulted in a reduction of [Ca(2+)]i, and of both BVR and APD. Increasing ICaL in the presence of thapsigargin restored APD but BVR remained low. In contrast, increasing ICaL with preserved Ca(2+) release increased both APD and BVR. Inhibition of Ca(2+) release with caffeine, as with thapsigargin, reduced BVR despite maintained APD. Simultaneous inhibition of Na(+)/Ca(2+) exchange and ICaL decreased APD and BVR to similar degrees, whilst increasing diastolic Ca(2+). Buffering of Ca(2+) transients with BAPTA reduced BVR for a given APD to a greater extent than buffering with EGTA, suggesting subsarcolemmal Ca(2+) transients modulated BVR to a larger extent than the cytosolic Ca(2+) transient. In conclusion, BVR in hypertrophied dog myocytes, at any APD, is strongly dependent on SR Ca(2+) release, which may act through modulation of the l-type Ca(2+) current in a subsarcolemmal microdomain.

  13. Myocytes oxygenation and high energy phosphate levels during hypoxia.

    Directory of Open Access Journals (Sweden)

    Mohammad Nurulqadr Jameel

    Full Text Available Decrease of ambient oxygen level has been used in myocytes culture experiments in examining the responsiveness to stress secondary to hypoxia. However, none of these studies measure the myocytes oxygenation levels resulting in ambiguity as to whether there is insufficient oxygen delivery. This study examined the hypothesis that at a basal myocardial work state, adequate myocyte oxygenation would be maintained until extremely low arterial pO2 levels were reached. Myocyte pO2 values in normal dogs were calculated from the myocardial deoxymyoglobin (Mb- δ levels using (1H-spectroscopy (MRS and were normalized to Mb-δ obtained after complete LAD occlusion. During Protocol 1 (n = 6, Mb-δ was measured during sequential reductions of the oxygen fraction of inspired gas (FIO2 from 40, 21, 15, 10, and 5%, while in protocol 2 (n = 10 Mb-δ was measured at FIO2 of 3%. Protocol 3 (n = 9 evaluated time course of Mb-δ during prolonged exposure to FIO2 of 5%. Myocardial blood flow (MBF was measured with microspheres and high energy phosphate (HEP levels were determined with (31P-MRS. MVO2 progressively increased in response to the progressive reduction of FIO2 that is accompanied by increased LV pressure, heart rate, and MBF. Mb-δ was undetectable during FIO2 values of 21, 15, 10, and 5%. However, FIO2 of 3% or prolonged exposure to FIO2 of 5% caused progressive increases of Mb-δ which were associated with decreases of PCr, ATP and the PCr/ATP ratio, as well as increases of inorganic phosphate. The intracellular PO2 values for 20% reductions of PCr and ATP were approximately 7.4 and 1.9 mmHg, respectively. These data demonstrate that in the in vivo system over a wide range of FIO2 and arterial pO2 levels, the myocyte pO2 values remain well above the K(m value with respect to cytochrome oxidase, and oxygen availability does not limit mitochondrial oxidative phosphorylation at 5% FIO2.

  14. Integration of a hospital information system in a Greek cardiac surgery hospital through specific education programs for health care personnel: development of nursing documentation.

    Science.gov (United States)

    Tsirintani, M

    1995-01-01

    This study represents an educative effort for integrating an innovative Hospital Information System (HIS) in Greece for quality impact on nursing practice and conductive research. The Hospital involved is the Onassis Cardiac Surgery Center (OCSC), a new 150 bedded state-of-the-art hospital in Athens. The aims of this study are the following: 1) To present the educational assessment concerning the HIS of Onassis Center, 2) To develop Nursing documentation to support the educational needs of nurses and clerks in correlation with the Nursing/Medical record of HIS, and 3) To show the meaning of continuing education for new and old hospital staff and the use of the system as an educative and consultative tool for decision support for health care personnel, especially nurses.

  15. Inibição da corrente de cálcio tipo L por tramadol e enantiômeros em miócitos cardíacos de ratos Inhibition of L-type calcium current by tramadol and enantiomers in cardiac myocytes from rats

    Directory of Open Access Journals (Sweden)

    Emiliano Medei

    2011-10-01

    -L, in which the peak amplitude was reduced by 64.4 ± 2.8% and 68.9 ± 5.8%, respectively at 0 mV (p > 0.05. Tramadol, (+- and (--tramadol shifted the steady-state inactivation of I Ca-L to more negative membrane potentials. Also, tramadol and (+-tramadol markedly shifted the time-dependent recovery curve of I Ca-L to the right and slowed down the recovery of I Ca-L from inactivation. The time constant was increased from 175.6 ± 18.6 to 305.0 ± 32.9 ms (p < 0.01 for tramadol and from 248.1 ± 28.1 ms to 359.0 ± 23.8 ms (p < 0.05 for (+-tramadol. The agonist of µ-opioid receptor DAMGO had no effect on the I Ca-L. CONCLUSION: The inhibition of I Ca-L induced by tramadol and its enantiomers was unrelated to the activation of opioid receptors and could explain, at least in part, their negative cardiac inotropic effect.

  16. Deferasirox and deferiprone remove cardiac iron in the iron-overloaded gerbil

    Science.gov (United States)

    WOOD, JOHN C.; OTTO-DUESSEL, MAYA; GONZALEZ, IGNACIO; AGUILAR, MICHELLE I.; SHIMADA, HIRO; NICK, HANSPETER; NELSON, MARVIN; MOATS, REX

    2010-01-01

    Introduction Deferasirox effectively controls liver iron concentration; however, little is known regarding its ability to remove stored cardiac iron. Deferiprone seems to have increased cardiac efficacy compared with traditional deferoxamine therapy. Therefore, the relative efficacy of deferasirox and deferiprone were compared in removing cardiac iron from iron-loaded gerbils. Methods Twenty-nine 8- to 10-week-old female gerbils underwent 10 weekly iron dextran injections of 200 mg/kg/week. Prechelation iron levels were assessed in 5 animals, and the remainder received deferasirox 100 mg/kg/D po QD (n = 8), deferiprone 375 mg/kg/D po divided TID (n = 8), or sham chelation (n = 8), 5 days/week for 12 weeks. Results Deferasirox reduced cardiac iron content 20.5%. No changes occurred in cardiac weight, myocyte hypertrophy, fibrosis, or weight-to-dry weight ratio. Deferasirox treatment reduced liver iron content 51%. Deferiprone produced comparable reductions in cardiac iron content (18.6% reduction). Deferiprone-treated hearts had greater mass (16.5% increase) and increased myocyte hypertrophy. Deferiprone decreased liver iron content 24.9% but was associated with an increase in liver weight and water content. Conclusion Deferasirox and deferiprone were equally effective in removing stored cardiac iron in a gerbil animal model, but deferasirox removed more hepatic iron for a given cardiac iron burden. PMID:17145573

  17. Effects of BmkTXKβ on electrophysiological properties of rabbit atrial myocytes

    Institute of Scientific and Technical Information of China (English)

    胡丹; 黄从新; 江洪; 李庚山; 曹志贱; 李文鑫; 王世敏

    2003-01-01

    Objective To investigate the effects of BmkTXKβ, a newly purified ‘long chain' peptide inhibitor of K+ channels from the Chinese scorpion Buthus martensi Karsch (BmK), on the electrophysiological properties of isolated rabbit atrial myocytes. Methods The standard whole-cell patch-clamp technique was used to study the effects of multiple concentrations of BmkTXKβ on potassium currents and action potentials. Results BmkTXKβ produced concentration-dependent prolongation of action potential duration at 20%, 50%, and 90% repolarization (APD20,50,90) without any use-dependence. Meanwhile, it had no significant effect on RMP, APA, or Vmax (n=9). At a dose of 1 μmol/L, BmkTXKβ decreased Ito by 41.4% (n=10, P0.05). Conclusions BmkTXKβ exerts direct blocking effects on several potassium channels involved in cardiac repolarization, and has a strong effect on prolonging the repolarization of rabbit cardiomyocytes without reverse frequency dependence. This finding suggests that BmkTXKβ could be a promising class Ⅲ drug for anti-arrhythmic therapy without the risk of proarrhythmia.

  18. Cardiac Sarcoidosis.

    Science.gov (United States)

    Birnie, David; Ha, Andrew C T; Gula, Lorne J; Chakrabarti, Santabhanu; Beanlands, Rob S B; Nery, Pablo

    2015-12-01

    Studies suggest clinically manifest cardiac involvement occurs in 5% of patients with pulmonary/systemic sarcoidosis. The principal manifestations of cardiac sarcoidosis (CS) are conduction abnormalities, ventricular arrhythmias, and heart failure. Data indicate that an 20% to 25% of patients with pulmonary/systemic sarcoidosis have asymptomatic (clinically silent) cardiac involvement. An international guideline for the diagnosis and management of CS recommends that patients be screened for cardiac involvement. Most studies suggest a benign prognosis for patients with clinically silent CS. Immunosuppression therapy is advocated for clinically manifest CS. Device therapy, with implantable cardioverter defibrillators, is recommended for some patients.

  19. [Prehospital cardiac resuscitation in Queretaro, Mexico. Report of 3 cases. Importance of an integral emergency medical care system].

    Science.gov (United States)

    Fraga-Sastrías, Juan Manuel; Aguilera-Campos, Andrea; Barinagarrementería-Aldatz, Fernando; Ortíz-Mondragón, Claudio; Asensio-Lafuente, Enrique

    2014-01-01

    In Mexico, out-of-hospital cardiac arrest is a health problem that represents 33,000 to 150,000 or more deaths per year. The few existent reports show mortality as high as 100% in contrast to some international reports that show higher survival rates. In Queretaro, during the last 5 years there were no successful resuscitation cases. However, in 2012 some patients were reported to have return of spontaneous circulation. We report in this article 3 cases with return of spontaneous circulation and pulse at arrival to the hospital. Two of the patients were discharged alive, one of them with poor cerebral performance category. Community cardiopulmonary resuscitation, early defibrillation and better emergency medical system response times, are related with survival. This poorly explored health problem in Queretaro could be increased with quality and good public education, bystander assisted cardiopulmonary resuscitation, police involvement in cardiopulmonary resuscitation and defibrillation, public access defibrillation programs and measurement of indicators and feedback for better results.

  20. Pre-transplantation specification of stem cells to cardiac lineage for regeneration of cardiac tissue.

    Science.gov (United States)

    Mayorga, Maritza; Finan, Amanda; Penn, Marc

    2009-03-01

    Myocardial infarction (MI) is a lead cause of mortality in the Western world. Treatment of acute MI is focused on restoration of antegrade flow which inhibits further tissue loss, but does not restore function to damaged tissue. Chronic therapy for injured myocardial tissue involves medical therapy that attempts to minimize pathologic remodeling of the heart. End stage therapy for chronic heart failure (CHF) involves inotropic therapy to increase surviving cardiac myocyte function or mechanical augmentation of cardiac performance. Not until the point of heart transplantation, a limited resource at best, does therapy focus on the fundamental problem of needing to replace injured tissue with new contractile tissue. In this setting, the potential for stem cell therapy has garnered significant interest for its potential to regenerate or create new contractile cardiac tissue. While to date adult stem cell therapy in clinical trials has suggested potential benefit, there is waning belief that the approaches used to date lead to regeneration of cardiac tissue. As the literature has better defined the pathways involved in cardiac differentiation, preclinical studies have suggested that stem cell pretreatment to direct stem cell differentiation prior to stem cell transplantation may be a more efficacious strategy for inducing cardiac regeneration. Here we review the available literature on pre-transplantation conditioning of stem cells in an attempt to better understand stem cell behavior and their readiness in cell-based therapy for myocardial regeneration.

  1. Myomaker is required for the fusion of fast-twitch myocytes in the zebrafish embryo.

    Science.gov (United States)

    Zhang, Weibin; Roy, Sudipto

    2017-03-01

    During skeletal muscle development, myocytes aggregate and fuse to form multinucleated muscle fibers. Inhibition of myocyte fusion is thought to significantly derail the differentiation of functional muscle fibers. Despite the purported importance of fusion in myogenesis, in vivo studies of this process in vertebrates are rather limited. Myomaker, a multipass transmembrane protein, has been shown to be the first muscle-specific fusion protein essential for myocyte fusion in the mouse. We have generated loss-of-function alleles in zebrafish myomaker, and found that fusion of myocytes into syncytial fast-twitch muscles was significantly compromised. However, mutant myocytes could be recruited to fuse with wild-type myocytes in chimeric embryos, albeit rather inefficiently. Conversely, overexpression of Myomaker was sufficient to induce hyperfusion among fast-twitch myocytes, and it also induced fusion among slow-twitch myocytes that are normally fusion-incompetent. In line with this, Myomaker overexpression also triggered fusion in another myocyte fusion mutant compromised in the function of the junctional cell adhesion molecule, Jam2a. We also provide evidence that Rac, a regulator of actin cytoskeleton, requires Myomaker activity to induce fusion, and that an approximately 3kb of myomaker promoter sequence, with multiple E-box motifs, is sufficient to direct expression within the fast-twitch muscle lineage. Taken together, our findings underscore a conserved role for Myomaker in vertebrate myocyte fusion. Strikingly, and in contrast to the mouse, homozygous myomaker mutants are viable and do not exhibit discernible locomotory defects. Thus, in the zebrafish, myocyte fusion is not an absolute requirement for skeletal muscle morphogenesis and function.

  2. Cardiac Malpositions

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Shi Joon; Im, Chung Gie; Yeon, Kyung Mo; Hasn, Man Chung [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1979-06-15

    Cardiac Malposition refers to any position of the heart other than a left-sided heart in a situs solitus individual. Associated cardiac malformations are so complex that even angiocardiographic and autopsy studies may not afford an accurate information. Although the terms and classifications used to describe the internal cardiac anatomy and their arterial connections in cardiac malpositions differ and tend to be confusing, common agreement exists on the need for a segmental approach to diagnosis. Authors present 18 cases of cardiac malpositions in which cardiac catheterization and angiocardiography were done at the Department of Radiology, Seoul National University Hospital between 1971 and 1979. Authors analyzed the clinical, radiographic, operative and autopsy findings with the emphasis on the angiocardiographic findings. The results are as follows: 1. Among 18 cases with cardiac malpositions, 6 cases had dextrocardia with situs inversus, 9 cases had dextrocardia with situs solitus and 3 cases had levocardia with situs inversus. 2. There was no genuine exception to visceroatrial concordance rule. 3. Associated cardiac malpositions were variable and complex with a tendency of high association of transposition and double outlet varieties with dextrocardia in situs solitus and levocardia in situs inversus. Only one in 6 cases of dextrocardia with situs inversus had pure transposition. 4. In two cases associated pulmonary atresia was found at surgery which was not predicted by angiocardiography. 5. Because many of the associated complex lesions can be corrected surgically provided the diagnosis is accurate, the selective biplane angiocardiography with or without cineradiography is essential.

  3. 3-OST-7 regulates BMP-dependent cardiac contraction.

    Directory of Open Access Journals (Sweden)

    Shiela C Samson

    2013-12-01

    Full Text Available The 3-O-sulfotransferase (3-OST family catalyzes rare modifications of glycosaminoglycan chains on heparan sulfate proteoglycans, yet their biological functions are largely unknown. Knockdown of 3-OST-7 in zebrafish uncouples cardiac ventricular contraction from normal calcium cycling and electrophysiology by reducing tropomyosin4 (tpm4 expression. Normal 3-OST-7 activity prevents the expansion of BMP signaling into ventricular myocytes, and ectopic activation of BMP mimics the ventricular noncontraction phenotype seen in 3-OST-7 depleted embryos. In 3-OST-7 morphants, ventricular contraction can be rescued by overexpression of tropomyosin tpm4 but not by troponin tnnt2, indicating that tpm4 serves as a lynchpin for ventricular sarcomere organization downstream of 3-OST-7. Contraction can be rescued by expression of 3-OST-7 in endocardium, or by genetic loss of bmp4. Strikingly, BMP misregulation seen in 3-OST-7 morphants also occurs in multiple cardiac noncontraction models, including potassium voltage-gated channel gene, kcnh2, affected in Romano-Ward syndrome and long-QT syndrome, and cardiac troponin T gene, tnnt2, affected in human cardiomyopathies. Together these results reveal 3-OST-7 as a key component of a novel pathway that constrains BMP signaling from ventricular myocytes, coordinates sarcomere assembly, and promotes cardiac contractile function.

  4. Characteristics of the Nonselective Cation Current (NSCCs) in Rabbit Left Ventricular Epicardial, Midmyocardial and Endocardial Myocytes

    Institute of Scientific and Technical Information of China (English)

    Min Zong; Xinchun Yang; Xiulan Liu; Liang Shi; Taifeng Liu

    2007-01-01

    Recent studies have described regional differences in the electrophysiology and pharmacology of ventricular myocardium in canine,feline,rat,guinea pig,and human hearts.This has been shown to be due to a smaller IKs and a lager sodium-calcium exchange current (INa-Ca ) and late INa in M region (deep subepicardial to midmyocardial).Studies from our laboratory have found a new repolarization current-nonselective cation current (NSCCs) existing in rabbit right ventricular myocytes.Methods We examined the characteristics of NSCCs in epicardial,M region,and endocardial cells isolated from the rabbit left ventricle with standard microelectrode and whole-cell patch-clamp techniques.The permeability to Na+,K + ,Li + ,Cs + but not to Cl-indicating that it was a nonselective cation current.Gd3+ (0.1 mmol/1) and La3+ (0.1 mmol/1) can block the current markedly.Results Further characterization of NSCCs was significantly smaller in M cells than in epicardial and endocardial cells.NSCCs current density was significantly smaller in M cells than in epicardial and endocardial cells.With repolarization to-80 mV,INs current density was (-0.44 ±0.05) PA/PF in endocardial cells,(-0.12 ±0.05) PA/PF in M cells and (-0.28 ±0.07) PA/PF in epicardial cells;and with repolarization to + 30 mV,INs current density was ( 1.09 ± 0.29) PA/PF in endocardial cells,(0.38 ± 0.09) PA/PF in M cells and (0.91 ± 0.32) PA/PF in epicardial cells.Conclusions Transmural dispersion of repolarization was due to the heterogeneity of NSCCs in rabbit left ventricle epicardial,endocardial myocytes and M cells.These findings may advance our understanding of the ionic basis for our understanding of factors contributing to the development of cardiac arrhythmias.

  5. Integration of cardiac computed tomography into pulmonary vein isolation in patients with paroxysmal atrial fibrillation; Integration einer praeinterventionellen Computertomografie des Herzens in die therapeutische Pulmonalvenenisolation bei Patienten mit paroxysmalem Vorhofflimmern

    Energy Technology Data Exchange (ETDEWEB)

    Weber, T.F. [Abt. Radiologie, Deutsches Krebsforschungszentrum, Heidelberg (Germany); Klemm, H.; Willems, S. [Klinik und Poliklinik fuer Kardiologie und Angiologie, Universitaetsklinikum Hamburg-Eppendorf (Germany); Koops, A.; Adam, G.; Begemann, P.G. [Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie, Universitaetsklinikum Hamburg-Eppendorf (Germany); Nagel, H.D. [Philips Medizin Systeme GmbH, Hamburg (Germany)

    2007-12-15

    Purpose: Detailed anatomic information of the left atrium is necessary for securely performing radiofrequency ablation of atrial fibrillation-triggering ectopies in the pulmonary vein ostia. In this study the impact of a preinterventionally acquired cardiac computed tomography (CT) on pulmonary vein isolation (PVI) was assessed. Materials and methods: Examinations of 54 patients with paroxysmal atrial fibrillation undergoing PVI were analyzed. In 27 patients a supplementary cardiac CT was obtained prior to PVI (CT group, 12 women, 15 men, 59.7 {+-} 9.9 years of age): 16 x 1.5 mm collimation, 0.2 pitch, 120 kV tube voltage, 400 effective mAs. The fluoroscopy time, effective dose and quantity of radiofrequency (RF) pulses of the following catheter ablation were compared to 27 patients undergoing stand-alone PVI (11 women, 16 men, 62.0 {+-} 9.9 years of age). Mann-Whitney tests served for statistical comparison. Results: CT datasets were successfully integrated into the ablation procedure of each patient in the CT group. The mean quantity of RF pulses was significantly lower in the CT group (22.1 {+-} 8.0 vs. 29.1 {+-} 11.9, p = 0.030), and a significant reduction of fluoroscopy time was found (41.8 {+-} 12.0 min vs. 51.2 {+-} 16.0 min, p = 0.005). Effective doses of the catheter ablation differed in an equivalent dimension but altogether not significantly (14.9 {+-} 10.0 mSv vs. 20.0 {+-} 16.0 mSv, p = 0.203). The mean additive effective dose of the cardiac CT was 85 {+-} 0.3 mSv. (orig.)

  6. Excess pressure integral predicts cardiovascular events independent of other risk factors in the conduit artery functional evaluation substudy of Anglo-Scandinavian Cardiac Outcomes Trial.

    Science.gov (United States)

    Davies, Justin E; Lacy, Peter; Tillin, Therese; Collier, David; Cruickshank, J Kennedy; Francis, Darrel P; Malaweera, Anura; Mayet, Jamil; Stanton, Alice; Williams, Bryan; Parker, Kim H; McG Thom, Simon A; Hughes, Alun D

    2014-07-01

    Excess pressure integral (XSPI), a new index of surplus work performed by the left ventricle, can be calculated from blood pressure waveforms and may indicate circulatory dysfunction. We investigated whether XSPI predicted future cardiovascular events and target organ damage in treated hypertensive individuals. Radial blood pressure waveforms were acquired by tonometry in 2069 individuals (aged, 63±8 years) in the Conduit Artery Functional Evaluation (CAFE) substudy of the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT). Measurements of left ventricular mass index (n=862) and common carotid artery intima media thickness (n=923) were also performed. XSPI and the integral of reservoir pressure were lower in people treated with amlodipine±perindopril than in those treated with atenolol±bendroflumethiazide, although brachial systolic blood pressure was similar. A total of 134 cardiovascular events accrued during a median 3.4 years of follow-up; XSPI was a significant predictor of cardiovascular events after adjustment for age and sex, and this relationship was unaffected by adjustment for conventional cardiovascular risk factors or Framingham risk score. XSPI, central systolic blood pressure, central augmentation pressure, central pulse pressure, and integral of reservoir pressure were correlated with left ventricular mass index, but only XSPI, augmentation pressure, and central pulse pressure were associated positively with carotid artery intima media thickness. Associations between left ventricular mass index, XSPI, and integral of reservoir pressure and carotid artery intima media thickness and XSPI were unaffected by multivariable adjustment for other covariates. XSPI is a novel indicator of cardiovascular dysfunction and independently predicts cardiovascular events and targets organ damage in a prospective clinical trial.

  7. Modulation of membrane potential by an acetylcholine-activated potassium current in trout atrial myocytes

    DEFF Research Database (Denmark)

    Molina, C.E.; Gesser, Hans; Llach, A.

    2007-01-01

    in both atrial myocytes and tissue, and this effect was antagonized by atropine. When applied alone, atropine prolonged the action potential in atrial tissue but had no effect on membrane potential, action potential, or Im in isolated atrial myocytes. This suggests that ACh-mediated activation...

  8. Efficient probabilistic model personalization integrating uncertainty on data and parameters: Application to eikonal-diffusion models in cardiac electrophysiology.

    Science.gov (United States)

    Konukoglu, Ender; Relan, Jatin; Cilingir, Ulas; Menze, Bjoern H; Chinchapatnam, Phani; Jadidi, Amir; Cochet, Hubert; Hocini, Mélèze; Delingette, Hervé; Jaïs, Pierre; Haïssaguerre, Michel; Ayache, Nicholas; Sermesant, Maxime

    2011-10-01

    Biophysical models are increasingly used for medical applications at the organ scale. However, model predictions are rarely associated with a confidence measure although there are important sources of uncertainty in computational physiology methods. For instance, the sparsity and noise of the clinical data used to adjust the model parameters (personalization), and the difficulty in modeling accurately soft tissue physiology. The recent theoretical progresses in stochastic models make their use computationally tractable, but there is still a challenge in estimating patient-specific parameters with such models. In this work we propose an efficient Bayesian inference method for model personalization using polynomial chaos and compressed sensing. This method makes Bayesian inference feasible in real 3D modeling problems. We demonstrate our method on cardiac electrophysiology. We first present validation results on synthetic data, then we apply the proposed method to clinical data. We demonstrate how this can help in quantifying the impact of the data characteristics on the personalization (and thus prediction) results. Described method can be beneficial for the clinical use of personalized models as it explicitly takes into account the uncertainties on the data and the model parameters while still enabling simulations that can be used to optimize treatment. Such uncertainty handling can be pivotal for the proper use of modeling as a clinical tool, because there is a crucial requirement to know the confidence one can have in personalized models.

  9. The effect of integrated cardiac rehabilitation versus treatment as usual for atrial fibrillation patients treated with ablation: the randomised CopenHeartRFA trial protocol

    Science.gov (United States)

    Risom, Signe Stelling; Zwisler, Ann-Dorth Olsen; Rasmussen, Trine Bernholdt; Sibilitz, Kirstine Lærum; Svendsen, Jesper Hastrup; Gluud, Christian; Hansen, Jane Lindschou; Winkel, Per; Thygesen, Lau Caspar; Perhonen, Merja; Hansen, Jim; Dunbar, Sandra B; Berg, Selina Kikkenborg

    2013-01-01

    Introduction Atrial fibrillation affects almost 2% of the population in the Western world. To preserve sinus rhythm, ablation is undertaken in symptomatic patients. Observational studies show that patients with atrial fibrillation often report a low quality of life and are less prone to be physically active due to fear of triggering fibrillation. Small trials indicate that exercise training has a positive effect on exercise capacity and mental health, and both patients with recurrent atrial fibrillation and in sinus rhythm may benefit from rehabilitation in managing life after ablation. No randomised trials have been published on cardiac rehabilitation for atrial fibrillation patients treated with ablation that includes exercise and psychoeducational components. Aim To test the effects of an integrated cardiac rehabilitation programme versus treatment as usual for patients with atrial fibrillation treated with ablation. Methods and analysis design The trial is a multicentre parallel arm design with 1:1 randomisation to the intervention and control group with blinded outcome assessment. 210 patients treated for atrial fibrillation with radiofrequency ablation will be included. The intervention consists of a rehabilitation programme including four psychoeducative consultations with a specially trained nurse and 12 weeks of individualised exercise training, plus the standard medical follow-up. Patients in the control group will receive the standard medical follow-up. The primary outcome measure is exercise capacity measured by the VO2 peak. The secondary outcome measure is self-rated mental health measured by the Short Form 36 questionnaire. Postintervention, qualitative interviews will be conducted in 10% of the intervention group. Ethics and dissemination The protocol is approved by the regional research ethics committee (number H-1-2011-135), the Danish Data Protection Agency (reg. nr. 2007-58-0015) and follows the latest version of the Declaration of Helsinki

  10. From syncitium to regulated pump: a cardiac muscle cellular update.

    Science.gov (United States)

    Korzick, Donna H

    2011-03-01

    The primary purpose of this article is to present a basic overview of some key teaching concepts that should be considered for inclusion in an six- to eight-lecture introductory block on the regulation of cardiac performance for graduate students. Within the context of cardiac excitation-contraction coupling, this review incorporates information on Ca(2+) microdomains and local control theory, with particular emphasis on the role of Ca(2+) sparks as a key regulatory component of ventricular myocyte contraction dynamics. Recent information pertaining to local Ca(2+) cycling in sinoatrial nodal cells (SANCs) as a mechanism underlying cardiac automaticity is also presented as part of the recently described coupled-clock pacemaker system. The details of this regulation are emerging; however, the notion that the sequestration and release of Ca(2+) from internal stores in SANCs (similar to that observed in ventricular myocytes) regulates the rhythmic excitation of the heart (i.e., membrane ion channels) is an important advancement in this area. The regulatory role of cardiac adrenergic receptors on cardiac rate and function is also included, and fundamental concepts related to intracellular signaling are discussed. An important point of emphasis is that whole organ cardiac dynamics can be traced back to cellular events regulating intracellular Ca(2+) homeostasis and, as such, provides an important conceptual framework from which students can begin to think about whole organ physiology in health and disease. Greater synchrony of Ca(2+)-regulatory mechanisms between ventricular and pacemaker cells should enhance student comprehension of complex regulatory phenomenon in cardiac muscle.

  11. Implementation of Contraction to Electrophysiological Ventricular Myocyte Models, and Their Quantitative Characterization via Post-Extrasystolic Potentiation.

    Science.gov (United States)

    Ji, Yanyan Claire; Gray, Richard A; Fenton, Flavio H

    2015-01-01

    Heart failure (HF) affects over 5 million Americans and is characterized by impairment of cellular cardiac contractile function resulting in reduced ejection fraction in patients. Electrical stimulation such as cardiac resynchronization therapy (CRT) and cardiac contractility modulation (CCM) have shown some success in treating patients with HF. Computer simulations have the potential to help improve such therapy (e.g. suggest optimal lead placement) as well as provide insight into the underlying mechanisms which could be beneficial. However, these myocyte models require a quantitatively accurate excitation-contraction coupling such that the electrical and contraction predictions are correct. While currently there are close to a hundred models describing the detailed electrophysiology of cardiac cells, the majority of cell models do not include the equations to reproduce contractile force or they have been added ad hoc. Here we present a systematic methodology to couple first generation contraction models into electrophysiological models via intracellular calcium and then compare the resulting model predictions to experimental data. This is done by using a post-extrasystolic pacing protocol, which captures essential dynamics of contractile forces. We found that modeling the dynamic intracellular calcium buffers is necessary in order to reproduce the experimental data. Furthermore, we demonstrate that in models the mechanism of the post-extrasystolic potentiation is highly dependent on the calcium released from the Sarcoplasmic Reticulum. Overall this study provides new insights into both specific and general determinants of cellular contractile force and provides a framework for incorporating contraction into electrophysiological models, both of which will be necessary to develop reliable simulations to optimize electrical therapies for HF.

  12. Continual electric field stimulation preserves contractile function of adult ventricular myocytes in primary culture.

    Science.gov (United States)

    Berger, H J; Prasad, S K; Davidoff, A J; Pimental, D; Ellingsen, O; Marsh, J D; Smith, T W; Kelly, R A

    1994-01-01

    To model with greater fidelity the electromechanical function of freshly isolated heart muscle cells in primary culture, we describe a technique for the continual electrical stimulation of adult myocytes at physiological frequencies for several days. A reusable plastic cover was constructed to fit standard, disposable 175-cm2 tissue culture flasks and to hold parallel graphite electrodes along the long axis of each flask, which treated a uniform electric field that resulted in a capture efficiency of ventricular myocytes of 75-80%. Computer-controlled amplifiers were designed to be capable of driving a number of flasks concurrently, each containing up to 4 x 10(6) myocytes, over a range of stimulation frequencies (from 0.1 to 7.0 Hz) with reversal of electrode polarity after each stimulus to prevent the development of pH gradients around each electrode. Unlike quiescent, unstimulated myocytes, the amplitude of contraction, and velocities of shortening and relaxation did not change in myocytes paced at 3-5 Hz for up to 72 h. The maintenance of normal contractile function in paced myocytes required mechanical contraction per se, since paced myocytes that remained quiescent due to the inclusion of 2.5 microM verapamil in the culture medium for 48 h also exhibited a decline in contractility when paced after verapamil removal. Similarly, pacing increased peak calcium current compared with quiescent cells that had not been paced. Thus myocyte contraction at physiological frequencies induced by continual uniform electric field stimulation in short-term primary culture in defining medium maintains some biophysical parameters of myocyte phenotype that are similar to those observed in freshly isolated adult ventricular myocytes.

  13. Influence of the availability of iron during hypoxia on the genes associated with apoptotic activity and local iron metabolism in rat H9C2 cardiomyocytes and L6G8C5 skeletal myocytes.

    Science.gov (United States)

    Dziegala, Magdalena; Kasztura, Monika; Kobak, Kamil; Bania, Jacek; Banasiak, Waldemar; Ponikowski, Piotr; Jankowska, Ewa A

    2016-10-01

    The differential availability of iron during hypoxia is presumed to affect the functioning of cardiac and skeletal myocytes. Rat H9C2 cardiomyocytes and L6G8C5 myocytes were cultured for 48 h in normoxic or hypoxic conditions at the optimal, reduced or increased iron concentration. The mRNA expression levels of markers of apoptosis [B‑cell lymphoma‑2 (Bcl2; inhibition) and Bcl‑2‑activated X protein (Bax; induction)], atrophy (Atrogin), glycolysis (pyruvate kinase 2; PKM2) and iron metabolism [transferrin receptor 1 (TfR1; iron importer), ferroportin 1 (FPN1; iron exporter), ferritin heavy chain (FTH; iron storage protein) and hepcidin (HAMP; iron regulator)] were determined using reverse transcription‑quantitative polymerase chain reaction, and cell viability was measured using an tetrazolium reduction assay. Cardiomyocytes and myocytes, when exposed to hypoxia, demonstrated an increased Bax/Bcl‑2 gene expression ratio (Pcell type (Pviability. The analogous alterations were observed in both cell types upon ammonium ferric citrate (AFC) treatment during hypoxia; however, the increased Bax/Bcl‑2 ratio and associated viability loss was lower compared with that in case of DFO treatment (Pcell types upon DFO during hypoxia demonstrated the increased expression of TfR1 and HAMP (all P0.6 and Pviability of cardiomyocytes and myocytes more severely compared with iron excess. In myocytes, during hypoxia iron may act in a protective manner, since the level of atrophy is decreased in the iron‑salt‑treated cells.

  14. Temporal evaluation of cardiac myocyte hypertrophy and hyperplasia in male rats secondary to chronic volume overload.

    Science.gov (United States)

    Du, Yan; Plante, Eric; Janicki, Joseph S; Brower, Gregory L

    2010-09-01

    The temporal myocardial remodeling induced by chronic ventricular volume overload in male rats was examined. Specifically, left ventricular (LV) cardiomyocyte length and width, sarcomere length, and number of nuclei were measured in male rats (n = 8 to 17) at 1, 3, 5, 7, 21, 35, and 56 days after creation of an infrarenal aortocaval fistula. In contrast to previously published reports of progressive increases in cardiomyocyte length and cross-sectional area at 5 days post-fistula and beyond in female hearts, cardiomyocyte length and width did not increase significantly in males during the first 35 days of volume overload. Furthermore, a significant decrease in cardiomyocyte length relative to age-matched controls, together with a reduced number of sarcomeres per cell, was noted in male hearts at 5 days post-fistula. There was a concurrent increase in the percentage of mononucleated cardiomyocytes from 11.6% to 18% at 5 days post-fistula. These initial differences could not be attributed to cardiomyocyte proliferation, and treatment with a microtubule stabilizing agent prevented them from occurring. The subsequent significant increase in LV weight without corresponding increases in cardiomyocyte dimensions is indicative of hyperplasia. Thus, these findings indicate hyperplasia resulting from cytokinesis of cardiomyocytes is a key mechanism, independent of hypertrophy, that contributes to the significant increase in LV mass in male hearts subjected to chronic volume overload.

  15. Stem cells can form gap junctions with cardiac myocytes and exert pro-arrhythmic effects

    Directory of Open Access Journals (Sweden)

    Nicoline Willemijn Smit

    2014-10-01

    Full Text Available Stem cell therapy has been suggested to be a promising option for regeneration of injured myocardium, for example following a myocardial infarction. For clinical use cell-based therapies have to be safe and applicable and are aimed to renovate the architecture of the heart. Yet for functional and coordinated activity synchronized with the host myocardium stem cells have to be capable of forming electrical connections with resident cardiomyocytes. In this paper we discuss whether stem cells are capable of establishing functional electrotonic connections with cardiomyocytes and whether these may generate a risk for arrhythmias. Application of stem cells in the clinical setting with outcomes concerning arrhythmogenic safety and future perspectives will also briefly be touched upon.

  16. T-box transcription factor TBX3 reprogrammes mature cardiac myocytes into pacemaker-like cells.

    NARCIS (Netherlands)

    Bakker, M.L.; Boink, G.J.; Boukens, B.J.; Verkerk, A.O.; Boogaard, M.W. van den; Haan, A.D. den; Hoogaars, W.M.; Buermans, H.P.; Bakker, J.M. de; Seppen, J.; Tan, H.L.; Moorman, A.F.; Hoen, P.A.C. 't; Christoffels, V.M.

    2012-01-01

    AIM: Treatment of disorders of the sinus node or the atrioventricular node requires insights into the molecular mechanisms of development and homoeostasis of these pacemaker tissues. In the developing heart, transcription factor TBX3 is required for pacemaker and conduction system development. Here,

  17. Antimyosin imaging in cardiac transplant rejection

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, L.L.; Cannon, P.J. (Department of Medicine, College of Physicians and Surgeons, Columbia University, New York (United States))

    1991-09-01

    Fab fragments of antibodies specific for cardiac myosin have been labeled with indium-111 and injected intravenously into animals and into patients with heart transplants. The antibodies, developed by Khaw, Haber, and co-workers, localize in cardiac myocytes that have been damaged irreversibly by ischemia, myocarditis, or the rejection process. After clearance of the labeled antibody from the cardiac blood pool, planar imaging or single photon emission computed tomography is performed. Scintigrams reveal the uptake of the labeled antimyosin in areas of myocardium undergoing transplant rejection. In animal studies, the degree of antimyosin uptake appears to correlate significantly with the degree of rejection assessed at necropsy. In patients, the correlation between scans and pathologic findings from endomyocardial biopsy is not as good, possibly because of sampling error in the endomyocardial biopsy technique. The scan results at 1 year correlate with either late complications (positive) or benign course (negative). Current limitations of the method include slow blood clearance, long half-life of indium-111, and hepatic uptake. Overcoming these limitations represents a direction for current research. It is possible that from these efforts a noninvasive approach to the diagnosis and evaluation of cardiac transplantation may evolve that will decrease the number of endomyocardial biopsies required to evaluate rejection. This would be particularly useful in infants and children. 31 references.

  18. Phospholemman: a novel cardiac stress protein.

    Science.gov (United States)

    Cheung, Joseph Y; Zhang, Xue-Qian; Song, Jianliang; Gao, Erhe; Rabinowitz, Joseph E; Chan, Tung O; Wang, Jufang

    2010-08-01

    Phospholemman (PLM), a member of the FXYD family of regulators of ion transport, is a major sarcolemmal substrate for protein kinases A and C in cardiac and skeletal muscle. In the heart, PLM co-localizes and co-immunoprecipitates with Na(+)-K(+)-ATPase, Na(+)/Ca(2+) exchanger, and L-type Ca(2+) channel. Functionally, when phosphorylated at serine(68), PLM stimulates Na(+)-K(+)-ATPase but inhibits Na(+)/Ca(2+) exchanger in cardiac myocytes. In heterologous expression systems, PLM modulates the gating of cardiac L-type Ca(2+) channel. Therefore, PLM occupies a key modulatory role in intracellular Na(+) and Ca(2+) homeostasis and is intimately involved in regulation of excitation-contraction (EC) coupling. Genetic ablation of PLM results in a slight increase in baseline cardiac contractility and prolongation of action potential duration. When hearts are subjected to catecholamine stress, PLM minimizes the risks of arrhythmogenesis by reducing Na(+) overload and simultaneously preserves inotropy by inhibiting Na(+)/Ca(2+) exchanger. In heart failure, both expression and phosphorylation state of PLM are altered and may partly account for abnormalities in EC coupling. The unique role of PLM in regulation of Na(+)-K(+)-ATPase, Na(+)/Ca(2+) exchanger, and potentially L-type Ca(2+) channel in the heart, together with the changes in its expression and phosphorylation in heart failure, make PLM a rational and novel target for development of drugs in our armamentarium against heart failure. Clin Trans Sci 2010; Volume 3: 189-196.

  19. Cardiac cAMP: production, hydrolysis, modulation and detection

    Directory of Open Access Journals (Sweden)

    Cédric eBOULARAN

    2015-10-01

    Full Text Available Cyclic adenosine 3’,5’-monophosphate (cAMP modulates a broad range of biological processes including the regulation of cardiac myocyte contractile function where it constitutes the main second messenger for β-adrenergic receptors’ signaling to fulfill positive chronotropic, inotropic and lusitropic effects. A growing number of studies pinpoint the role of spatial organization of the cAMP signaling as an essential mechanism to regulate cAMP outcomes in cardiac physiology. Here, we will briefly discuss the complexity of cAMP synthesis and degradation in the cardiac context, describe the way to detect it and review the main pharmacological arsenal to modulate its availability.

  20. Assembly of a functional 3D primary cardiac construct using magnetic levitation

    Directory of Open Access Journals (Sweden)

    Glauco Souza

    2016-07-01

    Full Text Available Easily assembled organotypic co-cultures have long been sought in medical research. In vitro tissue constructs with faithful representation of in vivo tissue characteristics are highly desirable for screening and characteristic assessment of a variety of tissue types. Cardiac tissue analogs are particularly sought after due to the phenotypic degradation and difficulty of culture of primary cardiac myocytes. This study utilized magnetic nanoparticles and primary cardiac myocytes in order to levitate and culture multicellular cardiac aggregates (MCAs. Cells were isolated from 2 day old Sprague Dawley rat hearts and subsequently two groups were incubated with either C1: 33 µL nanoshell/million cells or C2: 50 µL nanoshell/million cells. Varying numbers of cells for each concentration were cultured in a magnetic field in a 24 well plate and observed over a period of 12 days. Constructs generally formed spherical structures. Masson’s trichrome staining of a construct shows the presence of extracellular matrix protein, indicating the presence of functional fibroblasts. Many constructs exhibited noticeable contraction after 4 days of culture and continued contracting noticeably past day 9 of culture. Noticeable contractility indicates the presence of functional primary cardiac myocytes in culture. Phenotypic conservation of cardiac cells was ascertained using IHC staining by α-actinin and collagen. CD31 and fibrinogen were probed in order to assess localization of fibroblasts and endothelial cells. The study verifies a protocol for the use of magnetic levitation in order to rapidly assemble 3D cardiac like tissue with phenotypic and functional stability.

  1. Electrical stimulation directs engineered cardiac tissue to an age-matched native phenotype

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    Richard A Lasher

    2012-12-01

    Full Text Available Quantifying structural features of native myocardium in engineered tissue is essential for creating functional tissue that can serve as a surrogate for in vitro testing or the eventual replacement of diseased or injured myocardium. We applied three-dimensional confocal imaging and image analysis to quantitatively describe the features of native and engineered cardiac tissue. Quantitative analysis methods were developed and applied to test the hypothesis that environmental cues direct engineered tissue toward a phenotype resembling that of age-matched native myocardium. The analytical approach was applied to engineered cardiac tissue with and without the application of electrical stimulation as well as to age-matched and adult native tissue. Individual myocytes were segmented from confocal image stacks and assigned a coordinate system from which measures of cell geometry and connexin-43 spatial distribution were calculated. The data were collected from 9 nonstimulated and 12 electrically stimulated engineered tissue constructs and 5 postnatal day 12 and 7 adult hearts. The myocyte volume fraction was nearly double in stimulated engineered tissue compared to nonstimulated engineered tissue (0.34 ± 0.14 vs 0.18 ± 0.06 but less than half of the native postnatal day 12 (0.90 ± 0.06 and adult (0.91 ± 0.04 myocardium. The myocytes under electrical stimulation were more elongated compared to nonstimulated myocytes and exhibited similar lengths, widths, and heights as in age-matched myocardium. Furthermore, the percentage of connexin-43-positive membrane staining was similar in the electrically stimulated, postnatal day 12, and adult myocytes, whereas it was significantly lower in the nonstimulated myocytes. Connexin-43 was found to be primarily located at cell ends for adult myocytes and irregularly but densely clustered over the membranes of nonstimulated, stimulated, and postnatal day 12 myocytes. These findings support our hypothesis and reveal

  2. The Effect of U50488 on the Cardiac Rhythm and Intracellular Calcium in the Rat Heart.

    Institute of Scientific and Technical Information of China (English)

    Zhang Weimin; Xin Dalin; Wong Takming

    2000-01-01

    The effect of U50488, a selective k-opioid receptor agonist, on cardiac rhythm in the isolated perfused rat heart and intracellular calcium ([Ca2+] i) in the single ventricular myocyte were studied. The results showed that U50488 can induce arrhythmias dose-dependently in the isolated perfused rat heart and increase [Ca2+] i in the single ventricular myocyte. The effect of U50488 can be blocked by a selectivek-receptor antagonist, nor-binaltorphimine.The arrhythmogenic effects and the increase of [ Ca2 + ] i induced by U50488 were blocked by U73122, neomycin and streptomycin, which are selective phospolipase C inhibitors, but not by U73433, the inactive structural analog of U73122. These results demonstrated that the arrhythmogenic effect of cardiac k-receptor is due to activation of phosphoinositol/Ca2+ pathway.

  3. Computational approaches to understand cardiac electrophysiology and arrhythmias

    Science.gov (United States)

    Roberts, Byron N.; Yang, Pei-Chi; Behrens, Steven B.; Moreno, Jonathan D.

    2012-01-01

    Cardiac rhythms arise from electrical activity generated by precisely timed opening and closing of ion channels in individual cardiac myocytes. These impulses spread throughout the cardiac muscle to manifest as electrical waves in the whole heart. Regularity of electrical waves is critically important since they signal the heart muscle to contract, driving the primary function of the heart to act as a pump and deliver blood to the brain and vital organs. When electrical activity goes awry during a cardiac arrhythmia, the pump does not function, the brain does not receive oxygenated blood, and death ensues. For more than 50 years, mathematically based models of cardiac electrical activity have been used to improve understanding of basic mechanisms of normal and abnormal cardiac electrical function. Computer-based modeling approaches to understand cardiac activity are uniquely helpful because they allow for distillation of complex emergent behaviors into the key contributing components underlying them. Here we review the latest advances and novel concepts in the field as they relate to understanding the complex interplay between electrical, mechanical, structural, and genetic mechanisms during arrhythmia development at the level of ion channels, cells, and tissues. We also discuss the latest computational approaches to guiding arrhythmia therapy. PMID:22886409

  4. Raf-mediated cardiac hypertrophy in adult Drosophila.

    Science.gov (United States)

    Yu, Lin; Daniels, Joseph; Glaser, Alex E; Wolf, Matthew J

    2013-07-01

    In response to stress and extracellular signals, the heart undergoes a process called cardiac hypertrophy during which cardiomyocytes increase in size. If untreated, cardiac hypertrophy can progress to overt heart failure that causes significant morbidity and mortality. The identification of molecular signals that cause or modify cardiomyopathies is necessary to understand how the normal heart progresses to cardiac hypertrophy and heart failure. Receptor tyrosine kinase (RTK) signaling is essential for normal human cardiac function, and the inhibition of RTKs can cause dilated cardiomyopathies. However, neither investigations of activated RTK signaling pathways nor the characterization of hypertrophic cardiomyopathy in the adult fly heart has been previously described. Therefore, we developed strategies using Drosophila as a model to circumvent some of the complexities associated with mammalian models of cardiovascular disease. Transgenes encoding activated EGFR(A887T), Ras85D(V12) and Ras85D(V12S35), which preferentially signal to Raf, or constitutively active human or fly Raf caused hypertrophic cardiomyopathy as determined by decreased end diastolic lumen dimensions, abnormal cardiomyocyte fiber morphology and increased heart wall thicknesses. There were no changes in cardiomyocyte cell numbers. Additionally, activated Raf also induced an increase in cardiomyocyte ploidy compared with control hearts. However, preventing increases in cardiomyocyte ploidy using fizzy-related (Fzr) RNAi did not rescue Raf-mediated cardiac hypertrophy, suggesting that Raf-mediated polyploidization is not required for cardiac hypertrophy. Similar to mammals, the cardiac-specific expression of RNAi directed against MEK or ERK rescued Raf-mediated cardiac hypertrophy. However, the cardiac-specific expression of activated ERK(D334N), which promotes hyperplasia in non-cardiac tissues, did not cause myocyte hypertrophy. These results suggest that ERK is necessary, but not sufficient, for

  5. Raf-mediated cardiac hypertrophy in adult Drosophila

    Directory of Open Access Journals (Sweden)

    Lin Yu

    2013-07-01

    In response to stress and extracellular signals, the heart undergoes a process called cardiac hypertrophy during which cardiomyocytes increase in size. If untreated, cardiac hypertrophy can progress to overt heart failure that causes significant morbidity and mortality. The identification of molecular signals that cause or modify cardiomyopathies is necessary to understand how the normal heart progresses to cardiac hypertrophy and heart failure. Receptor tyrosine kinase (RTK signaling is essential for normal human cardiac function, and the inhibition of RTKs can cause dilated cardiomyopathies. However, neither investigations of activated RTK signaling pathways nor the characterization of hypertrophic cardiomyopathy in the adult fly heart has been previously described. Therefore, we developed strategies using Drosophila as a model to circumvent some of the complexities associated with mammalian models of cardiovascular disease. Transgenes encoding activated EGFRA887T, Ras85DV12 and Ras85DV12S35, which preferentially signal to Raf, or constitutively active human or fly Raf caused hypertrophic cardiomyopathy as determined by decreased end diastolic lumen dimensions, abnormal cardiomyocyte fiber morphology and increased heart wall thicknesses. There were no changes in cardiomyocyte cell numbers. Additionally, activated Raf also induced an increase in cardiomyocyte ploidy compared with control hearts. However, preventing increases in cardiomyocyte ploidy using fizzy-related (Fzr RNAi did not rescue Raf-mediated cardiac hypertrophy, suggesting that Raf-mediated polyploidization is not required for cardiac hypertrophy. Similar to mammals, the cardiac-specific expression of RNAi directed against MEK or ERK rescued Raf-mediated cardiac hypertrophy. However, the cardiac-specific expression of activated ERKD334N, which promotes hyperplasia in non-cardiac tissues, did not cause myocyte hypertrophy. These results suggest that ERK is necessary, but not sufficient, for Raf

  6. EGCG inhibits cardiomyocyte apoptosis in pressure overload-induced cardiac hypertrophy and protects cardiomyocytes from oxidative stress in rats

    Institute of Scientific and Technical Information of China (English)

    Rui SHENG; Zhen-lun GU; Mei-lin XIE; Wen-xuan ZHOU; Ci-yi GUO

    2007-01-01

    Aim: To investigate the effects of epigallocatechin gallate (EGCG) on pressure overload and hydrogen peroxide (H2O2) induced cardiac myocyte apoptosis. Methods: Cardiac hypertrophy was established in rats by abdominal aortic constriction. EGCG 25, 50 and 100 mg/kg were administered intragastrically (ig). Cultured newborn rat cardiomyocytes were preincubated with EGCG, and oxidative stress injury was induced by H2O2. Results: In cardiac hypertrophy induced by AC in rats, relative to the model group, EGCG 25, 50 and 100 mg/kg ig for 6weeks dose-dependently reduced systolic blood pressure (SBP) and heart weight indices, decreased malondialdehyde (MDA) content, and increased superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activity, both in serum and in the myocardium. Also, treatment with EGCG 50 and 100 mg/kg markedly improved cardiac structure and inhibited fibrosis in HE and van Gieson (VG) stain, and reduced apoptotic myocytes in the hypertrophic myocardium detected by terminal transferase-mediated dUTP-biotin nick end-labeling (TUNEL) assay. Inthe Western blot analysis, EGCG significantly inhibited pressure overload-inducedp53 increase and bcl-2 decrease. In H2O2-induced cardiomyocyte injury, when preincubated with myocytes for 6-48 h, EGCG 12.5-200 mg/L increased cell viability determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay. EGCG also attenuated H2O2-induced lactate dehydrogenase (LDH) release and MDA formation. Meanwhile, EGCG 50 and 100 mg/L significantly inhibited the cardiomyocyte apoptotic rate in flow cytometry. Conclusion: EGCG inhibits cardiac myocyte apoptosis and oxidative stress in pressure overload in-duced cardiac hypertrophy. Also, EGCG prevented cardiomyocyte apoptosis from oxidative stress in vitro. The mechanism might be related to the inhibitory effects of EGCG on p53 induction and bcl-2 decrease.

  7. The H{sub 1}–H{sub 2} domain of the α{sub 1} isoform of Na{sup +}–K{sup +}–ATPase is involved in ouabain toxicity in rat ventricular myocytes

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Chen; Li, Jun-xia; Guo, Hui-cai; Zhang, Li-nan; Guo, Wei; Meng, Jing; Wang, Yong-li, E-mail: wangyongli@gmail.com

    2012-07-01

    The composition of different isoforms of Na{sup +}-K{sup +}-ATPase (NKA, Na/K pump) in ventricular myocytes is an important factor in determining the therapeutic effect and toxicity of cardiac glycosides (CGs) on heart failure. The mechanism whereby CGs cause these effects is still not completely clear. In the present study, we prepared two site-specific antibodies (SSA78 and WJS) against the H{sub 1}–H{sub 2} domain of α{sub 1} and α{sub 2} isoforms of NKA in rat heart, respectively, and compared their influences on the effect of ouabain (OUA) in isolated rat ventricular myocytes. SSA78 or WJS, which can specifically bind with the α{sub 1} or α{sub 2} isoform, were assessed with enzyme linked immunosorbent assay (ELISA), Western blot and immunofluorescent staining methods. Preincubation of myocytes with SSA78 inhibited low OUA affinity pump current but not high OUA affinity pump current, reduced the rise in cytosolic calcium concentration ([Ca{sup 2+}]{sub i}), attenuated mitochondrial Ca{sup 2+} overload, restored mitochondrial membrane potential reduction, and delayed the decrease of the myocardial contractile force as well as the occurrence of arrhythmic contraction induced by high concentrations (1 mM) but not low concentrations (1 μM) of OUA. Similarly, preincubation of myocytes with WJS inhibited high OUA affinity pump current, reduced the increase of [Ca{sup 2+}]{sub i} and the contractility induced by 1 μM but not that induced by 1 mM OUA. These results indicate that the H{sub 1}–H{sub 2} domain of the NKA α{sub 1} isoform mediates OUA-induced cardiac toxicity in rat ventricular myocytes, and inhibitors for this binding site may be used as an adjunct to CGs treatment for cardiovascular disease. -- Highlights: ► We prepared two antibodies against the H{sub 1}-H{sub 2} domain of α{sub 1} and α{sub 2} isoforms of NKA. ► The H{sub 1}-H{sub 2} domain of the NKA α{sub 1} isoform mediates OUA-induced cardiac toxicity. ► The H{sub 1}-H{sub 2

  8. Muscarinic 2 Receptors Modulate Cardiac Proteasome Function in a Protein Kinase G-dependent Manner

    OpenAIRE

    Ranek, Mark J.; Kost, Curtis K.; Hu, Chengjun; Martin, Douglas S.; Wang, Xuejun

    2014-01-01

    Proteasome function insufficiency and inadequate protein quality control are strongly implicated in a large subset of cardiovascular disease and may play an important role in their pathogenesis. Protein degradation by the ubiquitin proteasome system can be physiologically regulated. Cardiac muscarinic 2 (M2) receptors were pharmacologically interrogated in intact mice and cultured neonatal rat ventricular myocytes (NRVMs). Proteasome-mediated proteolysis was measured with a surrogate misfolde...

  9. A compartmentalized mathematical model of the β1-adrenergic signaling system in mouse ventricular myocytes.

    Directory of Open Access Journals (Sweden)

    Vladimir E Bondarenko

    Full Text Available The β1-adrenergic signaling system plays an important role in the functioning of cardiac cells. Experimental data shows that the activation of this system produces inotropy, lusitropy, and chronotropy in the heart, such as increased magnitude and relaxation rates of [Ca(2+]i transients and contraction force, and increased heart rhythm. However, excessive stimulation of β1-adrenergic receptors leads to heart dysfunction and heart failure. In this paper, a comprehensive, experimentally based mathematical model of the β1-adrenergic signaling system for mouse ventricular myocytes is developed, which includes major subcellular functional compartments (caveolae, extracaveolae, and cytosol. The model describes biochemical reactions that occur during stimulation of β1-adrenoceptors, changes in ionic currents, and modifications of Ca(2+ handling system. Simulations describe the dynamics of major signaling molecules, such as cyclic AMP and protein kinase A, in different subcellular compartments; the effects of inhibition of phosphodiesterases on cAMP production; kinetics and magnitudes of phosphorylation of ion channels, transporters, and Ca(2+ handling proteins; modifications of action potential shape and duration; magnitudes and relaxation rates of [Ca(2+]i transients; changes in intracellular and transmembrane Ca(2+ fluxes; and [Na(+]i fluxes and dynamics. The model elucidates complex interactions of ionic currents upon activation of β1-adrenoceptors at different stimulation frequencies, which ultimately lead to a relatively modest increase in action potential duration and significant increase in [Ca(2+]i transients. In particular, the model includes two subpopulations of the L-type Ca(2+ channels, in caveolae and extracaveolae compartments, and their effects on the action potential and [Ca(2+]i transients are investigated. The presented model can be used by researchers for the interpretation of experimental data and for the developments of

  10. Cardiac echinococcosis

    Directory of Open Access Journals (Sweden)

    Ivanović-Krstić Branislava A.

    2002-01-01

    Full Text Available Cardiac hydatid disease is rare. We report on an uncommon hydatid cyst localized in the right ventricular wall, right atrial wall tricuspid valve left atrium and pericard. A 33-year-old woman was treated for cough, fever and chest pain. Cardiac echocardiograpic examination revealed a round tumor (5.8 x 4 cm in the right ventricular free wall and two smaller cysts behind that tumor. There were cysts in right atrial wall and tricuspidal valve as well. Serologic tests for hydatidosis were positive. Computed tomography finding was consistent with diagnosis of hydatid cyst in lungs and right hylar part. Surgical treatment was rejected due to great risk of cardiac perforation. Medical treatment with albendazole was unsuccessful and the patient died due to systemic hydatid involvement of the lungs, liver and central nervous system.

  11. Controlling the contractile strength of engineered cardiac muscle by hierarchal tissue architecture.

    Science.gov (United States)

    Feinberg, Adam W; Alford, Patrick W; Jin, Hongwei; Ripplinger, Crystal M; Werdich, Andreas A; Sheehy, Sean P; Grosberg, Anna; Parker, Kevin Kit

    2012-08-01

    The heart is a muscular organ with a wrapping, laminar structure embedded with neural and vascular networks, collagen fibrils, fibroblasts, and cardiac myocytes that facilitate contraction. We hypothesized that these non-muscle components may have functional benefit, serving as important structural alignment cues in inter- and intra-cellular organization of cardiac myocytes. Previous studies have demonstrated that alignment of engineered myocardium enhances calcium handling, but how this impacts actual force generation remains unclear. Quantitative assays are needed to determine the effect of alignment on contractile function and muscle physiology. To test this, micropatterned surfaces were used to build 2-dimensional myocardium from neonatal rat ventricular myocytes with distinct architectures: confluent isotropic (serving as the unaligned control), confluent anisotropic, and 20 μm spaced, parallel arrays of multicellular myocardial fibers. We combined image analysis of sarcomere orientation with muscular thin film contractile force assays in order to calculate the peak sarcomere-generated stress as a function of tissue architecture. Here we report that increasing peak systolic stress in engineered cardiac tissues corresponds with increasing sarcomere alignment. This change is larger than would be anticipated from enhanced calcium handling and increased uniaxial alignment alone. These results suggest that boundary conditions (heterogeneities) encoded in the extracellular space can regulate muscle tissue function, and that structural organization and cytoskeletal alignment are critically important for maximizing peak force generation.

  12. FHL2 prevents cardiac hypertrophy in mice with cardiac-specific deletion of ROCK2.

    Science.gov (United States)

    Okamoto, Ryuji; Li, Yuxin; Noma, Kensuke; Hiroi, Yukio; Liu, Ping-Yen; Taniguchi, Masaya; Ito, Masaaki; Liao, James K

    2013-04-01

    The Rho-associated coiled-coil containing kinases, ROCK1 and ROCK2, are important regulators of cell shape, migration, and proliferation through effects on the actin cytoskeleton. However, it is not known whether ROCK2 plays an important role in the development of cardiac hypertrophy. To determine whether the loss of ROCK2 could prevent cardiac hypertrophy, cardiomyocyte-specific ROCK2-null (c-ROCK2(-/-)) were generated using conditional ROCK2(flox/flox) mice and α-myosin heavy-chain promoter-driven Cre recombinase transgenic mice. Cardiac hypertrophy was induced by Ang II infusion (400 ng/kg/min, 28 d) or transverse aortic constriction (TAC). Under basal conditions, hemodynamic parameters, cardiac anatomy, and function of c-ROCK2(-/-) mice were comparable to wild-type (WT) mice. However, following Ang II infusion or TAC, c-ROCK2(-/-) mice exhibited a substantially smaller increase in heart-to-body weight ratio, left ventricular mass, myocyte cross-sectional area, hypertrophy-related fetal gene expression, intraventricular fibrosis, cardiac apoptosis, and oxidative stress compared to control mice. Deletion of ROCK2 in cardiomyocytes leads to increased expression of four-and-a-half LIM-only protein-2 (FHL2) and FHL2-mediated inhibition of serum response factor (SRF) and extracellular signal-regulated mitogen-activated protein kinase (ERK). Knockdown of FHL2 expression in ROCK2-deficient cardiomyocytes or placing ROCK2-haploinsufficient (ROCK2(+/-)) mice on FHL2(+/-)-haploinsufficient background restored the hypertrophic response to Ang II. These results indicate that cardiomyocyte ROCK2 is essential for the development of cardiac hypertrophy and that up-regulation of FHL2 may contribute to the antihypertrophic phenotype that is observed in cardiac-specific ROCK2-deficient mice.

  13. Cardiac Rehabilitation

    Science.gov (United States)

    ... your risk of future heart problems, and to improve your health and quality of life. Cardiac rehabilitation programs increase ... exercise routine at home or at a local gym. You may also continue to ... health concerns. Education about nutrition, lifestyle and weight loss ...

  14. H⁺-activated Na⁺ influx in the ventricular myocyte couples Ca²⁺-signalling to intracellular pH.

    Science.gov (United States)

    Garciarena, Carolina D; Youm, Jae Boum; Swietach, Pawel; Vaughan-Jones, Richard D

    2013-08-01

    Acid extrusion on Na(+)-coupled pH-regulatory proteins (pH-transporters), Na(+)/H(+) exchange (NHE1) and Na(+)-HCO3(-) co-transport (NBC), drives Na(+) influx into the ventricular myocyte. This H(+)-activated Na(+)-influx is acutely up-regulated at pHipH-transporter) with gap-junctions at intercalated discs. Overall Na(+)-influx via NBC is considerably lower, but much is co-localised with L-type Ca(2+)-channels in transverse-tubules. Through a functional coupling with Na(+)/Ca(2+) exchange (NCX), H(+)-activated Na(+)-influx increases sarcoplasmic-reticular Ca(2+)-loading and release during intracellular acidosis. This raises Ca(2+)-transient amplitude, rescuing it from direct H(+)-inhibition. Functional coupling is biochemically regulated and linked to membrane receptors, through effects on NHE1 and NBC. It requires adequate cytoplasmic Na(+)-mobility, as NHE1 and NCX are spatially separated (up to 60μm). The relevant functional NCX activity must be close to dyads, as it exerts no effect on bulk diastolic Ca(2+). H(+)-activated Na(+)-influx is up-regulated during ischaemia-reperfusion and some forms of maladaptive hypertrophy and heart failure. It is thus an attractive system for therapeutic manipulation. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes".

  15. Proteasome inhibition slightly improves cardiac function in mice with hypertrophic cardiomyopathy.

    Science.gov (United States)

    Schlossarek, Saskia; Singh, Sonia R; Geertz, Birgit; Schulz, Herbert; Reischmann, Silke; Hübner, Norbert; Carrier, Lucie

    2014-01-01

    A growing line of evidence indicates a dysfunctional ubiquitin-proteasome system (UPS) in cardiac diseases. Anti-hypertrophic effects and improved cardiac function have been reported after treatment with proteasome inhibitors in experimental models of cardiac hypertrophy. Here we tested whether proteasome inhibition could also reverse the disease phenotype in a genetically-modified mouse model of hypertrophic cardiomyopathy (HCM), which carries a mutation in Mybpc3, encoding the myofilament protein cardiac myosin-binding protein C. At 7 weeks of age, homozygous mutant mice (KI) have 39% higher left ventricular mass-to-body-weight ratio and 29% lower fractional area shortening (FAS) than wild-type (WT) mice. Both groups were treated with epoxomicin (0.5 mg/kg/day) or vehicle for 1 week via osmotic minipumps. Epoxomicin inhibited the chymotrypsin-like activity by ~50% in both groups. All parameters of cardiac hypertrophy (including the fetal gene program) were not affected by epoxomicin treatment in both groups. In contrast, FAS was 12% and 35% higher in epoxomicin-treated than vehicle-treated WT and KI mice, respectively. To identify which genes or pathways could be involved in this positive effect, we performed a transcriptome analysis in KI and WT neonatal cardiac myocytes, treated or not with the proteasome inhibitor MG132 (1 μM, 24 h). This revealed 103 genes (four-fold difference; 5% FDR) which are commonly regulated in both KI and WT cardiac myocytes. Thus, even in genetically-modified mice with manifest HCM, proteasome inhibition showed beneficial effects, at least with regard to cardiac function. Targeting the UPS in cardiac diseases remains therefore a therapeutic option.

  16. Cardiac Calcification

    Directory of Open Access Journals (Sweden)

    Morteza Joorabian

    2011-05-01

    Full Text Available There is a spectrum of different types of cardiac"ncalcifications with the importance and significance"nof each type of cardiac calcification, especially"ncoronary artery calcification. Radiologic detection of"ncalcifications within the heart is quite common. The"namount of coronary artery calcification correlates"nwith the severity of coronary artery disease (CAD."nCalcification of the aortic or mitral valve may indicate"nhemodynamically significant valvular stenosis."nMyocardial calcification is a sign of prior infarction,"nwhile pericardial calcification is strongly associated"nwith constrictive pericarditis. A spectrum of different"ntypes of cardiac calcifications (linear, annular,"ncurvilinear,... could be seen in chest radiography and"nother imaging modalities. So a carful inspection for"ndetection and reorganization of these calcifications"nshould be necessary. Numerous modalities exist for"nidentifying coronary calcification, including plain"nradiography, fluoroscopy, intravascular ultrasound,"nMRI, echocardiography, and conventional, helical and"nelectron-beam CT (EBCT. Coronary calcifications"ndetected on EBCT or helical CT can be quantifie,"nand a total calcification score (Cardiac Calcification"nScoring may be calculated. In an asymptomatic"npopulation and/or patients with concomitant risk"nfactors like diabetes mellitus, determination of the"npresence of coronary calcifications identifies the"npatients at risk for future myocardial infarction and"ncoronary artery disease. In patients without coronary"ncalcifications, future cardiovascular events could"nbe excluded. Therefore, detecting and recognizing"ncalcification related to the heart on chest radiography"nand other imaging modalities such as fluoroscopy, CT"nand echocardiography may have important clinical"nimplications.

  17. Integrative Cardiac Health Project (ICHP)

    Science.gov (United States)

    2012-09-01

    exercise, meditation, yoga and group support, which may lead to improved CHD risk factor profiles and genetic markers of coronary artery disease...lack of consistent improvement within the control arm further proves the benefits of a team-base, patient-centered lifestyle change model in improving

  18. Modulation of stretch-induced myocyte remodeling and gene expression by nitric oxide: a novel role for lipoma preferred partner in myofibrillogenesis.

    Science.gov (United States)

    Hooper, Charlotte L; Paudyal, Anju; Dash, Philip R; Boateng, Samuel Y

    2013-05-15

    Prolonged hemodynamic load as a result of hypertension eventually leads to maladaptive cardiac adaptation and heart failure. The signaling pathways that underlie these changes are still poorly understood. The adaptive response to mechanical load is mediated by mechanosensors that convert the mechanical stimuli into a biological response. We examined the effect of cyclic mechanical stretch on myocyte adaptation using neonatal rat ventricular myocytes with 10% (adaptive) or 20% (maladaptive) maximum strain at 1 Hz for 48 h to mimic in vivo mechanical stress. Cells were also treated with and without nitro-L-arginine methyl ester (L-NAME), a general nitric oxide synthase (NOS) inhibitor to suppress NO production. Maladaptive 20% mechanical stretch led to a significant loss of intact sarcomeres that were rescued by L-NAME (P 100%; P < 0.05; n = 5 cultures) and lipoma preferred partner (LPP), a novel cardiac protein (by 80%; P < 0.05; n = 4 cultures). L-NAME also significantly altered the subcellular localization of LPP and MLP in a manner that favored growth and adaptation. These findings suggest that NO participates in stretch-mediated adaptation. The use of isoform selective NOS inhibitors indicated a complex interaction between inducible NOS and neuronal NOS isoforms regulate gene expression. LPP knockdown by small intefering RNA led to formation of α-actinin aggregates and Z bodies showing that myofibrillogenesis was impaired. There was an upregulation of E3 ubiquitin ligase (MUL1) by 75% (P < 0.05; n = 5 cultures). This indicates that NO contributes to stretch-mediated adaptation via the upregulation of proteins associated with mechansensing and myofibrillogenesis, thereby presenting potential therapeutic targets during the progression of heart failure.

  19. Salubrinal Alleviates Pressure Overload-Induced Cardiac Hypertrophy by Inhibiting Endoplasmic Reticulum Stress Pathway

    Science.gov (United States)

    Rani, Shilpa; Sreenivasaiah, Pradeep Kumar; Cho, Chunghee; Kim, Do Han

    2017-01-01

    Pathological hypertrophy of the heart is closely associated with endoplasmic reticulum stress (ERS), leading to maladaptations such as myocardial fibrosis, induction of apoptosis, and cardiac dysfunctions. Salubrinal is a known selective inhibitor of protein phosphatase 1 (PP1) complex involving dephosphorylation of phospho-eukaryotic translation initiation factor 2 subunit (p-eIF2)-α, the key signaling process in the ERS pathway. In this study, the effects of salubrinal were examined on cardiac hypertrophy using the mouse model of transverse aortic constriction (TAC) and cell model of neonatal rat ventricular myocytes (NRVMs). Treatment of TAC-induced mice with salubrinal (0.5 mg·kg−1·day−1) alleviated cardiac hypertrophy and tissue fibrosis. Salubrinal also alleviated hypertrophic growth in endothelin 1 (ET1)-treated NRVMs. Therefore, the present results suggest that salubrinal may be a potentially efficacious drug for treating pathological cardiac remodeling. PMID:28152298

  20. Inhibitory Effects of Glycyrrhetinic Acid on the Delayed Rectifier Potassium Current in Guinea Pig Ventricular Myocytes and HERG Channel

    Directory of Open Access Journals (Sweden)

    Delin Wu

    2013-01-01

    Full Text Available Background. Licorice has long been used to treat many ailments including cardiovascular disorders in China. Recent studies have shown that the cardiac actions of licorice can be attributed to its active component, glycyrrhetinic acid (GA. However, the mechanism of action remains poorly understood. Aim. The effects of GA on the delayed rectifier potassium current (IK, the rapidly activating (IKr and slowly activating (IKs components of IK, and the HERG K+ channel expressed in HEK-293 cells were investigated. Materials and Methods. Single ventricular myocytes were isolated from guinea pig myocardium using enzymolysis. The wild type HERG gene was stably expressed in HEK293 cells. Whole-cell patch clamping was used to record IK (IKr, IKs and the HERG K+ current. Results. GA (1, 5, and 10 μM inhibited IK (IKr, IKs and the HERG K+ current in a concentration-dependent manner. Conclusion. GA significantly inhibited the potassium currents in a dose- and voltage-dependent manner, suggesting that it exerts its antiarrhythmic action through the prolongation of APD and ERP owing to the inhibition of IK (IKr, IKs and HERG K+ channel.

  1. Effect of siRNA silencing of inducible co-stimulatory molecule on myocardial cell hypertrophy after cardiac infarction in rats.

    Science.gov (United States)

    Wang, W M; Liu, Z; Chen, G

    2016-05-20

    As the most common cardiac disease, myocardial infarction is followed by hypertrophy of cardiac myocytes and reconstruction of ventricular structure. The up-regulation of a series of factors including metalloproteinases, inflammatory factors, and growth factors after primary infarction lead to the hypertrophy, apoptosis, necrosis, and fibroblast proliferation in cardiac muscle tissues. Recent studies have reported on the potency of small interfering RNA (siRNA) in treating cardiac diseases. We thus investigated the efficacy of inducible co-stimulatory molecule (ICOS)-specific siRNA silencing in myocardial hypertrophy in a cardiac infarction rat model. This cardiac infarction model was prepared by ligating the left anterior descending coronary artery. ICOS-siRNA treatment was administered in parallel with non-sense siRNA. After 18 days, the cross-sectional area of cardiac muscle tissues and the left ventricle weight index were measured, along with ICOS mRNA and protein expression levels, and pathological staining. Compared to those in the control groups, in myocardial infarcted rats, the application of ICOS-siRNA effectively decreased the left ventricle weight index, as well as the surface area of cardiac myocytes. Both mRNA and protein levels of ICOS were also significantly decreased. HE staining was consistent with these results. In conclusion, ICOS-targeted siRNA can effectively silence gene expression of ICOS, and provided satisfactory treatment efficacy for myocardial cell hypertrophy after infarction.

  2. Apoptosis of ventricular myocytes: a means to an end.

    Science.gov (United States)

    Regula, Kelly M; Kirshenbaum, Lorrie A

    2005-01-01

    One of the most compelling issues to impact on contemporary cardiology is arguably the phenomenon of programmed cell death or apoptosis. Studies in the nematode Caenorhabditis elegans provided the first indication that determinants of cell fate crucial for normal worm development were under genetic influences of the ced-3 and ced-9 genes, which promote or prevent cell death, respectively. Extrapolation of these seminal findings led to the discovery of the mammalian ced-3 and ced-9 homologs, which broadly encompass a family of cellular cysteine proteases known collectively as caspases and the Bcl-2 proteins. In quiescent cells, caspases exist as inactive zymogens that are readily activated by autocatalytic processes or by other caspases following a death signal. The caspase-dependent cleavage of intracellular substrates results in the biochemical dismantling of the cell and morphological features characteristic of apoptosis. Recently, a mitochondrial death pathway for apoptosis has been proposed. Perturbations to mitochondria resulting in the loss of mitochondrial membrane potential, DeltaPsim, permeability transition pore (PTP) opening and the release of pro-apoptotic factors by mitochondria including cytochrome c, second mitochondrial activator of caspases/direct IAP binding protein with low pI (Smac/DIABLO), AIF, and others are considered terminal events in the apoptotic pathway. Bcl-2 and related family members are characterized by their ability to promote or prevent cell death. These proteins exert their pro- or anti-apoptosis function by impinging on components of the cell death pathway that underlie caspase activation, mitochondrial dysfunction or both. The limited regenerative potential of the adult cardiac muscle itself, together with the heightened and exciting possibility of regenerating cardiac muscle with cardiac progenitor cells, acknowledges the need for new strategies to suppress and/or prevent inappropriate cardiac cell death in patients with

  3. Fetal reprogramming and senescence in hypoplastic left heart syndrome and in human pluripotent stem cells during cardiac differentiation.

    Science.gov (United States)

    Gaber, Naila; Gagliardi, Mark; Patel, Pranali; Kinnear, Caroline; Zhang, Cindy; Chitayat, David; Shannon, Patrick; Jaeggi, Edgar; Tabori, Uri; Keller, Gordon; Mital, Seema

    2013-09-01

    Hypoplastic left heart syndrome (HLHS) is a severe cardiac malformation characterized by left ventricle (LV) hypoplasia and abnormal LV perfusion and oxygenation. We studied hypoxia-associated injury in fetal HLHS and human pluripotent stem cells during cardiac differentiation to assess the effect of microenvironmental perturbations on fetal cardiac reprogramming. We studied LV myocardial samples from 32 HLHS and 17 structurally normal midgestation fetuses. Compared with controls, the LV in fetal HLHS samples had higher nuclear expression of hypoxia-inducible factor-1α but lower angiogenic growth factor expression, higher expression of oncogenes and transforming growth factor (TGF)-β1, more DNA damage and senescence with cell cycle arrest, fewer cardiac progenitors, myocytes and endothelial lineages, and increased myofibroblast population (P cells (SMCs) had less DNA damage compared with endothelial cells and myocytes. We recapitulated the fetal phenotype by subjecting human pluripotent stem cells to hypoxia during cardiac differentiation. DNA damage was prevented by treatment with a TGF-β1 inhibitor (P cells). The hypoplastic LV in fetal HLHS samples demonstrates hypoxia-inducible factor-1α up-regulation, oncogene-associated cellular senescence, TGF-β1-associated fibrosis and impaired vasculogenesis. The phenotype is recapitulated by subjecting human pluripotent stem cells to hypoxia during cardiac differentiation and rescued by inhibition of TGF-β1. This finding suggests that hypoxia may reprogram the immature heart and affect differentiation and development.

  4. Ionic mechanisms underlying cardiac toxicity of the organochloride solvent trichloromethane.

    Science.gov (United States)

    Zhou, Yuan; Wu, Hui-Jun; Zhang, Yan-Hui; Sun, Hai-Ying; Wong, Tak-Ming; Li, Gui-Rong

    2011-12-18

    Trichloromethane (chloroform) is widely used for industrial chemical synthesis and also as an organic solvent in laboratories or ingredient of pesticides. Sudden death resulted from cardiac arrhythmias has been reported in clinic with acute trichloromethane intoxication. The present study was designed to investigate ionic mechanisms underlying arrhythmogenic effect (cardiac toxicity) of trichloromethane in isolated rat hearts and ventricular myocytes and HEK 293 cells stably expressing human Nav1.5, HCN2, or hERG channel using conventional electrophysiological approaches. It was found that trichloromethane (5mM) induced bradycardia and atrial-ventricular conduction blockade or ventricular fibrillation, and inhibited cardiac contractile function in isolated rat hearts. It shortened action potential duration (APD) in isolated rat ventricular myocytes, and increased the threshold current for triggering action potential, but had no effect on the inward rectifier K(+) current I(K1). However, trichloromethane significantly inhibited the L-type calcium current I(Ca.L) and the transient outward potassium current I(to) in a concentration-dependent manner (IC(50)s: 1.01 and 2.4mM, respectively). In HEK 293 cells stably expressing cardiac ion channel genes, trichloromethane reduced hNav1.5, HCN2, and hERG currents with IC(50)s of 8.2, 3.3, and 4.0mM, respectively. These results demonstrate for the first time that trichloromethane can induce bradycardia or ventricular fibrillation, and the arrhythmogenic effect of trichloromethane is related to the inhibition of multiple ionic currents including I(Ca.L), I(to), I(Na), HCN2, and hERG channels.

  5. Tetrodotoxin Sensitivity of the Vertebrate Cardiac Na+ Current

    Directory of Open Access Journals (Sweden)

    Jaakko Haverinen

    2011-11-01

    Full Text Available Evolutionary origin and physiological significance of the tetrodotoxin (TTX resistance of the vertebrate cardiac Na+ current (INa is still unresolved. To this end, TTX sensitivity of the cardiac INa was examined in cardiac myocytes of a cyclostome (lamprey, three teleost fishes (crucian carp, burbot and rainbow trout, a clawed frog, a snake (viper and a bird (quail. In lamprey, teleost fishes, frog and bird the cardiac INa was highly TTX-sensitive with EC50-values between 1.4 and 6.6 nmol·L−1. In the snake heart, about 80% of the INa was TTX-resistant with EC50 value of 0.65 μmol·L−1, the rest being TTX-sensitive (EC50 = 0.5 nmol·L−1. Although TTX-resistance of the cardiac INa appears to be limited to mammals and reptiles, the presence of TTX-resistant isoform of Na+ channel in the lamprey heart suggest an early evolutionary origin of the TTX-resistance, perhaps in the common ancestor of all vertebrates.

  6. Cardiac sympathetic nerve terminal function in congestive heart failure

    Institute of Scientific and Technical Information of China (English)

    Chang-seng LIANG

    2007-01-01

    Increased cardiac release of norepinephrine (NE) and depleted cardiac stores of NE are two salient features of the human failing heart. Researches from my labo-ratory have shown that these changes are accompanied by a functional defect of NE uptake in the cardiac sympathetic nerve terminals. Our studies have shown that the decrease of NE uptake is caused by reduction of NE transporter density in the sympathetic nerve endings, and this change is responsible, at least in part, for the increased myocardial interstitial NE, decreased myocardial adrenoceptor density, and increased myocyte apoptosis in experimental cardiomyopathies. We have also provided evidence in both intact animals and cultured PC12 cells that the decrease of NE transporter is induced by the actions of oxidative metabolites of exogenous NE, involving endoplasmic reticulum stress and impaired N-glycosylation of the NE transporter. This change in the cardiac sympathetic NE uptake function, as demonstrated by [123I] metaiodobenzylguanidine in human studies, may not only serve as an important prognostic variable in patients with congestive heart failure, but also be used as a surrogate for the efficacies of various therapeutic interventions for heart failure. Finally, increasing evidence suggests and further studies are needed to show that the cardiac sympathetic nerve terminal function may be a direct target for pharmacologic treatment of congestive heart failure.

  7. Evaluation of Cardiac Toxicity Biomarkers in Rats from Different Laboratories.

    Science.gov (United States)

    Kim, Kyuri; Chini, Naseem; Fairchild, David G; Engle, Steven K; Reagan, William J; Summers, Sandra D; Mirsalis, Jon C

    2016-12-01

    There is a great need for improved diagnostic and prognostic accuracy of potential cardiac toxicity in drug development. This study reports the evaluation of several commercially available biomarker kits by 3 institutions (SRI, Eli Lilly, and Pfizer) for the discrimination between myocardial degeneration/necrosis and cardiac hypertrophy as well as the assessment of the interlaboratory and interplatform variation in results. Serum concentrations of natriuretic peptides (N-terminal pro-atrial natriuretic peptide [NT-proANP] and N-terminal pro-brain natriuretic peptide [NT-proBNP]), cardiac and skeletal troponins (cTnI, cTnT, and sTnI), myosin light chain 3 (Myl3), and fatty acid binding protein 3 (FABP3) were assessed in rats treated with minoxidil (MNX) and isoproterenol (ISO). MNX caused increased heart-to-body weight ratios and prominent elevations in NT-proANP and NT-proBNP concentrations detected at 24-hr postdose without elevation in troponins, Myl3, or FABP3 and with no abnormal histopathological findings. ISO caused ventricular leukocyte infiltration, myocyte fibrosis, and necrosis with increased concentrations of the natriuretic peptides, cardiac troponins, and Myl3. These results reinforce the advantages of a multimarker strategy in elucidating the underlying cause of cardiac insult and detecting myocardial tissue damage at 24-hr posttreatment. The interlaboratory and interplatform comparison analyses also showed that the data obtained from different laboratories and platforms are highly correlated and reproducible, making these biomarkers widely applicable in preclinical studies.

  8. Myocardial damage in dogs affected by heartworm disease (Dirofilaria immitis): immunohistochemical study of cardiac myoglobin and troponin I in naturally infected dogs.

    Science.gov (United States)

    Carretón, E; Grandi, G; Morchón, R; Simón, F; Passeri, B; Cantoni, A M; Kramer, L; Montoya-Alonso, J A

    2012-10-26

    It has recently been reported that dogs affected by canine heartworm disease (Dirofilaria immitis) can show an increase in plasma levels of myoglobin and cardiac troponin I, two markers of muscle/myocardial injury. In order to determine if this increase is due to myocardial damage, the right ventricle of 24 naturally infected dogs was examined by routine histology and immunohistochemistry with anti-myoglobin and anti-cardiac troponin I antibodies. Microscopic lesions included necrosis and myocyte vacuolization, and were associated with loss of staining for one or both proteins. Results confirm that increased levels of myoglobin and cardiac troponin I are indicative of myocardial damage in dogs affected by heartworm disease.

  9. Metabolites of MDMA induce oxidative stress and contractile dysfunction in adult rat left ventricular myocytes.

    Science.gov (United States)

    Shenouda, Sylvia K; Varner, Kurt J; Carvalho, Felix; Lucchesi, Pamela A

    2009-03-01

    Repeated administration of 3,4-methylenedioxymethamphetamine (MDMA) (ecstasy) produces eccentric left ventricular (LV) dilation and diastolic dysfunction. While the mechanism(s) underlying this toxicity are unknown, oxidative stress plays an important role. MDMA is metabolized into redox cycling metabolites that produce superoxide. In this study, we demonstrated that metabolites of MDMA induce oxidative stress and contractile dysfunction in adult rat left ventricular myocytes. Metabolites of MDMA used in this study included alpha-methyl dopamine, N-methyl alpha-methyl dopamine and 2,5-bis(glutathion-S-yl)-alpha-MeDA. Dihydroethidium was used to detect drug-induced increases in reactive oxygen species (ROS) production in ventricular myocytes. Contractile function and changes in intracellular calcium transients were measured in paced (1 Hz), Fura-2 AM loaded, myocytes using the IonOptix system. Production of ROS in ventricular myocytes treated with MDMA was not different from control. In contrast, all three metabolites of MDMA exhibited time- and concentration-dependent increases in ROS that were prevented by N-acetyl-cysteine (NAC). The metabolites of MDMA, but not MDMA alone, significantly decreased contractility and impaired relaxation in myocytes stimulated at 1 Hz. These effects were prevented by NAC. Together, these data suggest that MDMA-induced oxidative stress in the left ventricle can be due, at least in part, to the metabolism of MDMA to redox active metabolites.

  10. Computational analysis of the regulation of Ca2+ dynamics in rat ventricular myocytes

    Science.gov (United States)

    Bugenhagen, Scott M.; Beard, Daniel A.

    2015-10-01

    Force-frequency relationships of isolated cardiac myocytes show complex behaviors that are thought to be specific to both the species and the conditions associated with the experimental preparation. Ca2+ signaling plays an important role in shaping the force-frequency relationship, and understanding the properties of the force-frequency relationship in vivo requires an understanding of Ca2+ dynamics under physiologically relevant conditions. Ca2+ signaling is itself a complicated process that is best understood on a quantitative level via biophysically based computational simulation. Although a large number of models are available in the literature, the models are often a conglomeration of components parameterized to data of incompatible species and/or experimental conditions. In addition, few models account for modulation of Ca2+ dynamics via β-adrenergic and calmodulin-dependent protein kinase II (CaMKII) signaling pathways even though they are hypothesized to play an important regulatory role in vivo. Both protein-kinase-A and CaMKII are known to phosphorylate a variety of targets known to be involved in Ca2+ signaling, but the effects of these pathways on the frequency- and inotrope-dependence of Ca2+ dynamics are not currently well understood. In order to better understand Ca2+ dynamics under physiological conditions relevant to rat, a previous computational model is adapted and re-parameterized to a self-consistent dataset obtained under physiological temperature and pacing frequency and updated to include β-adrenergic and CaMKII regulatory pathways. The necessity of specific effector mechanisms of these pathways in capturing inotrope- and frequency-dependence of the data is tested by attempting to fit the data while including and/or excluding those effector components. We find that: (1) β-adrenergic-mediated phosphorylation of the L-type calcium channel (LCC) (and not of phospholamban (PLB)) is sufficient to explain the inotrope-dependence; and (2) that

  11. Signaling Pathways Involved in Cardiac Hypertrophy

    Institute of Scientific and Technical Information of China (English)

    Tao Zewei; Li Longgui

    2006-01-01

    Cardiac hypertrophy is the heart's response to a variety of extrinsic and intrinsic stimuli that impose increased biomechanical stress.Traditionally, it has been considered a beneficial mechanism; however, sustained hypertrophy has been associated with a significant increase in the risk of cardiovascular disease and mortality. Delineating intracellular signaling pathways involved in the different aspects of cardiac hypertrophy will permit future improvements in potential targets for therapeutic intervention. Generally, there are two types of cardiac hypertrophies, adaptive hypertrophy, including eutrophy (normal growth) and physiological hypertrophy (growth induced by physical conditioning), and maladaptive hypertrophy, including pathologic or reactive hypertrophy (growth induced by pathologic stimuli) and hypertrophic growth caused by genetic mutations affecting sarcomeric or cytoskeletal proteins. Accumulating observations from animal models and human patients have identified a number of intracellular signaling pathways that characterized as important transducers of the hypertrophic response,including calcineurin/nuclear factor of activated Tcells, phosphoinositide 3-kinases/Akt (PI3Ks/Akt),G protein-coupled receptors, small G proteins,MAPK, PKCs, Gp130/STAT'3, Na+/H+ exchanger,peroxisome proliferator-activated receptors, myocyte enhancer factor 2/histone deacetylases, and many others. Furthermore, recent evidence suggests that adaptive cardiac hypertrophy is regulated in large part by the growth hormone/insulin-like growth factors axis via signaling through the PI3K/Akt pathway. In contrast, pathological or reactive hypertrophy is triggered by autocrine and paracrine neurohormonal factors released during biomechanical stress that signal through the Gq/phosphorlipase C pathway, leading to an increase in cytosolic calcium and activation of PKC.

  12. Elevated NF-κB activation is conserved in human myocytes cultured from obese type 2 diabetic patients and attenuated by AMP-activated protein kinase

    DEFF Research Database (Denmark)

    Green, Charlotte Jane; Pedersen, Maria; Pedersen, Bente K;

    2011-01-01

    To examine whether the inflammatory phenotype found in obese and diabetic individuals is preserved in isolated, cultured myocytes and to assess the effectiveness of pharmacological AMP-activated protein kinase (AMPK) activation upon the attenuation of inflammation in these myocytes....

  13. Calcium-sensing receptor activation contributed to apoptosis stimulates TRPC6 channel in rat neonatal ventricular myocytes

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yi-hua [Department of Clinical Laboratory, The Second Affiliated Hospital of Harbin Medical University, Harbin 150086 (China); Li, Yong-quan [Harbin Medical University, Harbin 150086 (China); Feng, Shan-li [Department of Clinical Laboratory, The Second Affiliated Hospital of Harbin Medical University, Harbin 150086 (China); Li, Bao-xin; Pan, Zhen-wei [Department of Pharmacology, Harbin Medical University, Harbin 150086 (China); Xu, Chang-qing [Department of Pathophysiology, Harbin Medical University, Harbin 150086 (China); Li, Ting-ting [Department of Clinical Laboratory, The Second Affiliated Hospital of Harbin Medical University, Harbin 150086 (China); Yang, Bao-feng, E-mail: syh200415@yahoo.com.cn [Department of Pharmacology, Harbin Medical University, Harbin 150086 (China)

    2010-04-16

    Capacitative calcium entry (CCE) refers to the influx of calcium through plasma membrane channels activated on depletion of endoplasmic sarcoplasmic/reticulum (ER/SR) Ca{sup 2+} stores, which is performed mainly by the transient receptor potential (TRP) channels. TRP channels are expressed in cardiomyocytes. Calcium-sensing receptor (CaR) is also expressed in rat cardiac tissue and plays an important role in mediating cardiomyocyte apoptosis. However, there are no data regarding the link between CaR and TRP channels in rat heart. In this study, in rat neonatal myocytes, by Ca{sup 2+} imaging, we found that the depletion of ER/SR Ca{sup 2+} stores by thapsigargin (TG) elicited a transient rise in cytoplasmic Ca{sup 2+} ([Ca{sup 2+}]{sub i}), followed by sustained increase depending on extracellular Ca{sup 2+}. But, TRP channels inhibitor (SKF96365), not L-type channels or the Na{sup +}/Ca{sup 2+} exchanger inhibitors, inhibited [Ca{sup 2+}]{sub i} relatively high. Then, we found that the stimulation of CaR with its activator gadolinium chloride (GdCl{sub 3}) or by an increased extracellular Ca{sup 2+}([Ca{sup 2+}]{sub o}) increased the concentration of intracelluar Ca{sup 2+}, whereas, the sustained elevation of [Ca{sup 2+}]{sub i} was reduced in the presence of SKF96365. Similarly, the duration of [Ca{sup 2+}]{sub i} increase was also shortened in the absence of extracellular Ca{sup 2+}. Western blot analysis showed that GdCl{sub 3} increased the expression of TRPC6, which was reversed by SKF96365. Additionally, SKF96365 reduced cardiomyocyte apoptosis induced by GdCl{sub 3}. Our results suggested that CCE exhibited in rat neonatal myocytes and CaR activation induced Ca{sup 2+}-permeable cationic channels TRPCs to gate the CCE, for which TRPC6 was one of the most likely candidates. TRPC6 channel was functionally coupled with CaR to enhance the cardiomyocyte apoptosis.

  14. Elevated NF-κB activation is conserved in human myocytes cultured from obese type 2 diabetic patients and attenuated by AMP-activated protein kinase

    DEFF Research Database (Denmark)

    Green, Charlotte Jane; Pedersen, Maria; Pedersen, Bente K

    2011-01-01

    To examine whether the inflammatory phenotype found in obese and diabetic individuals is preserved in isolated, cultured myocytes and to assess the effectiveness of pharmacological AMP-activated protein kinase (AMPK) activation upon the attenuation of inflammation in these myocytes.......To examine whether the inflammatory phenotype found in obese and diabetic individuals is preserved in isolated, cultured myocytes and to assess the effectiveness of pharmacological AMP-activated protein kinase (AMPK) activation upon the attenuation of inflammation in these myocytes....

  15. Study of transmembrane La3+ movement in rat ventricular myocytes by the patch-clamp technique

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    We have studied transmembrane La3+ movement in rat ventricular myocytes for the first time by using the whole-cell patch-clamp recording mode. La3+ (0.01-5.0 mmol/L) could not bring out inward currents through the L-type calcium channel in rat ventricular myocytes, while it could enter the cells by the same way carried by 1μmol/L ionomycin. When the outward Na+ concentration gradient is formed, La3+ can enter the cells via Na-Ca exchange, and the exchange currentsincrease with the increase of external La3+ concentrations. But compared with Na-Ca exchange currents in the same concentration, the former is only 14%-38% of the latter. The patch-clamp experiment indicates that La3+ normally can not enter ventricular myocytes through L-type calcium channel, but it can enter the cells via Na-Ca exchange.

  16. Mature adipocyte-derived dedifferentiated fat cells can transdifferentiate into skeletal myocytes in vitro.

    Science.gov (United States)

    Kazama, Tomohiko; Fujie, Masaki; Endo, Tuyoshi; Kano, Koichiro

    2008-12-19

    We have previously reported the establishment of preadipocyte cell lines, termed dedifferentiated fat (DFAT) cells, from mature adipocytes of various animals. DFAT cells possess long-term viability and can redifferentiate into adipocytes both in vivo and in vitro. Furthermore, DFAT cells can transdifferentiate into osteoblasts and chondrocytes under appropriate culture conditions. However, it is unclear whether DFAT cells are capable of transdifferentiating into skeletal myocytes, which is common in the mesodermal lineage. Here, we show that DFAT cells can be induced to transdifferentiate into skeletal myocytes in vitro. Myogenic induction of DFAT cells resulted in the expression of MyoD and myogenin, followed by cell fusion and formation of multinucleated cells expressing sarcomeric myosin heavy chain. These results indicate that DFAT cells derived from mature adipocytes can transdifferentiate into skeletal myocytes in vitro.

  17. Docosahexaenoic acid has influence on action potentials and transient outward potassium currents of ventricular myocytes

    Directory of Open Access Journals (Sweden)

    Yang Zhen-Yu

    2010-04-01

    Full Text Available Abstract Background There are many reports about the anti-arrhythmic effects of ω-3 polyunsaturated fatty acids, however, the mechanisms are still not completely delineated. The purpose of this study was to investigate the characteristics of action potentials and transient outward potassium currents (Ito of Sprague-Dawley rat ventricular myocytes and the effects of docosahexaenoic acid (DHA on action potentials and Ito. Methods The calcium-tolerant rat ventricular myocytes were isolated by enzyme digestion. Action potentials and Ito of epicardial, mid-cardial and endocardial ventricular myocytes were recorded by whole-cell patch clamp technique. Results 1. Action potential durations (APDs were prolonged from epicardial to endocardial ventricular myocytes (P 2. Ito current densities were decreased from epicardial to endocardial ventricular myocytes, which were 59.50 ± 15.99 pA/pF, 29.15 ± 5.53 pA/pF, and 12.29 ± 3.62 pA/pF, respectively at +70 mV test potential (P 3. APDs were gradually prolonged with the increase of DHA concentrations from 1 μmol/L to 100 μmol/L, however, APDs changes were not significant as DHA concentrations were in the range of 0 μmol/L to 1 μmol/L. 4. Ito currents were gradually reduced with the increase of DHA concentrations from 1 μmol/L to 100 μmol/L, and its half-inhibited concentration was 5.3 μmol/L. The results showed that there were regional differences in the distribution of action potentials and Ito in rat epicardial, mid-cardial and endocardial ventricular myocytes. APDs were prolonged and Ito current densities were gradually reduced with the increase of DHA concentrations. Conclusion The anti-arrhythmia mechanisms of DHA are complex, however, the effects of DHA on action potentials and Ito may be one of the important causes.

  18. Non-cardiac QTc-prolonging drugs and the risk of sudden cardiac death

    NARCIS (Netherlands)

    Straus, SMJM; Sturkenboom, MCJM; Bleumink, GS; van der Lei, J; de Graeff, PA; Kingma, JH; Stricker, BHC

    2005-01-01

    Aims To assess the association between the use of non-cardiac QTc-prolonging drugs and the risk of sudden cardiac death. Methods and results A population-based case-control study was performed in the Integrated Primary Care Information (IPCI) project, a longitudinal observational database with compl

  19. Genetically engineered cardiac pacemaker: Stem cells transfected with HCN2 gene and myocytes—A model

    Science.gov (United States)

    Kanani, S.; Pumir, A.; Krinsky, V.

    2008-01-01

    One of the successfully tested methods to design genetically engineered cardiac pacemaker cells consists in transfecting a human mesenchymal stem cell (hMSC) with a HCN2 gene and connecting it to a myocyte. We develop and study a mathematical model, describing a myocyte connected to a hMSC transfected with a HCN2 gene. The cardiac action potential is described both with the simple Beeler Reuter model, as well as with the elaborate dynamic Luo Rudy model. The HCN2 channel is described by fitting electrophysiological records, in the spirit of Hodgkin Huxley. The model shows that oscillations can occur in a pair myocyte-stem cell, that was not observed in the experiments yet. The model predicted that: (1) HCN pacemaker channels can induce oscillations only if the number of expressed I channels is low enough. At too high an expression level of I channels, oscillations cannot be induced, no matter how many pacemaker channels are expressed. (2) At low expression levels of I channels, a large domain of values in the parameter space (n, N) exists, where oscillations should be observed. We denote N the number of expressed pacemaker channels in the stem cell, and n the number of gap junction channels coupling the stem cell and the myocyte. (3) The expression levels of I channels observed in ventricular myocytes, both in the Beeler Reuter and in the dynamic Luo Rudy models are too high to allow to observe oscillations. With expression levels below ˜1/4 of the original value, oscillations can be observed. The main consequence of this work is that in order to obtain oscillations in an experiment with a myocyte-stem cell pair, increasing the values of n, N is unlikely to be helpful, unless the expression level of I has been reduced enough. The model also allows us to explore levels of gene expression not yet achieved in experiments, and could be useful to plan new experiments, aimed at improving the robustness of the oscillations.

  20. Components of the interleukin-33/ST2 system are differentially expressed and regulated in human cardiac cells and in cells of the cardiac vasculature.

    Science.gov (United States)

    Demyanets, Svitlana; Kaun, Christoph; Pentz, Richard; Krychtiuk, Konstantin A; Rauscher, Sabine; Pfaffenberger, Stefan; Zuckermann, Andreas; Aliabadi, Arezu; Gröger, Marion; Maurer, Gerald; Huber, Kurt; Wojta, Johann

    2013-07-01

    Interleukin-33 (IL-33) is a recently described member of the IL-1 family of cytokines, which was identified as a ligand for the ST2 receptor. Components of the IL-33/ST2 system were shown to be expressed in normal and pressure overloaded human myocardium, and soluble ST2 (sST2) has emerged as a prognostic biomarker in myocardial infarction and heart failure. However, expression and regulation of IL-33 in human adult cardiac myocytes and fibroblasts was not tested before. In this study we found that primary human adult cardiac fibroblasts (HACF) and human adult cardiac myocytes (HACM) constitutively express nuclear IL-33 that is released during cell necrosis. Tumor necrosis factor (TNF)-α, interferon (IFN)-γ and IL-1β significantly increased both IL-33 protein and IL-33 mRNA expression in HACF and HACM as well as in human coronary artery smooth muscle cells (HCASMC). The nuclear factor-κB (NF-κB) inhibitor dimethylfumarate inhibited TNF-α- and IL-1β-induced IL-33 production as well as nuclear translocation of p50 and p65 NF-κB subunits in these cells. Mitogen-activated protein/extracellular signal-regulated kinase inhibitor U0126 abrogated TNF-α-, IFN-γ-, and IL-1β-induced and Janus-activated kinase inhibitor I reduced IFN-γ-induced IL-33 production. We detected IL-33 mRNA in human myocardial tissue from patients undergoing heart transplantation (n=27) where IL-33 mRNA levels statistically significant correlated with IFN-γ (r=0.591, p=0.001) and TNF-α (r=0.408, p=0.035) mRNA expression. Endothelial cells in human heart expressed IL-33 as well as ST2 protein. We also reveal that human cardiac and vascular cells have different distribution patterns of ST2 isoforms (sST2 and transmembrane ST2L) mRNA expression and produce different amounts of sST2 protein. Both human macrovascular (aortic and coronary artery) and heart microvascular endothelial cells express specific mRNA for both ST2 isoforms (ST2L and sST2) and are a source for sST2 protein, whereas

  1. Cardiac MRI in Athletes

    NARCIS (Netherlands)

    Luijkx, T.

    2012-01-01

    Cardiac magnetic resonance imaging (CMR) is often used in athletes to image cardiac anatomy and function and is increasingly requested in the context of screening for pathology that can cause sudden cardiac death (SCD). In this thesis, patterns of cardiac adaptation to sports are investigated with C

  2. TGF-β1, released by myofibroblasts, differentially regulates transcription and function of sodium and potassium channels in adult rat ventricular myocytes.

    Directory of Open Access Journals (Sweden)

    Kuljeet Kaur

    Full Text Available Cardiac injury promotes fibroblasts activation and differentiation into myofibroblasts, which are hypersecretory of multiple cytokines. It is unknown whether any of such cytokines are involved in the electrophysiological remodeling of adult cardiomyocytes. We cultured adult cardiomyocytes for 3 days in cardiac fibroblast conditioned medium (FCM from adult rats. In whole-cell voltage-clamp experiments, FCM-treated myocytes had 41% more peak inward sodium current (I(Na density at -40 mV than myocytes in control medium (p3 fold greater in FCM than control, which suggested that FCM effects could be mediated by TGF-β1. This was confirmed by pre-treatment with TGF-β1 neutralizing antibody, which abolished the FCM-induced changes in both I(Na and I(to. In current-clamp experiments TGF-β1 (10 ng/ml prolonged the action potential duration at 30, 50, and 90 repolarization (p<0.05; at 50 ng/ml it gave rise to early afterdepolarizations. In voltage-clamp experiments, TGF-β1 increased I(Na density in a dose-dependent manner without affecting voltage dependence of activation or inactivation. I(Na density was -36.25±2.8 pA/pF in control, -59.17±6.2 pA/pF at 0.1 ng/ml (p<0.01, and -58.22±6.6 pA/pF at 1 ng/ml (p<0.01. In sharp contrast, I(to density decreased from 22.2±1.2 pA/pF to 12.7±0.98 pA/pF (p<0.001 at 10 ng/ml. At 1 ng/ml TGF-β1 significantly increased SCN5A (Na(V1.5 (+73%; p<0.01, while reducing KCNIP2 (Kchip2; -77%; p<0.01 and KCND2 (K(V4.2; -50% p<0.05 mRNA levels. Further, the TGF-β1-induced increase in I(Na was mediated through activation of the PI3K-AKT pathway via phosphorylation of FOXO1 (a negative regulator of SCN5A. TGF-β1 released by myofibroblasts differentially regulates transcription and function of the main cardiac sodium channel and of the channel responsible for the transient outward current. The results provide new mechanistic insight into the electrical remodeling associated with myocardial injury.

  3. TGF-β1, Released by Myofibroblasts, Differentially Regulates Transcription and Function of Sodium and Potassium Channels in Adult Rat Ventricular Myocytes

    Science.gov (United States)

    Kaur, Kuljeet; Zarzoso, Manuel; Ponce-Balbuena, Daniela; Guerrero-Serna, Guadalupe; Hou, Luqia; Musa, Hassan; Jalife, José

    2013-01-01

    Cardiac injury promotes fibroblasts activation and differentiation into myofibroblasts, which are hypersecretory of multiple cytokines. It is unknown whether any of such cytokines are involved in the electrophysiological remodeling of adult cardiomyocytes. We cultured adult cardiomyocytes for 3 days in cardiac fibroblast conditioned medium (FCM) from adult rats. In whole-cell voltage-clamp experiments, FCM-treated myocytes had 41% more peak inward sodium current (INa) density at −40 mV than myocytes in control medium (p3 fold greater in FCM than control, which suggested that FCM effects could be mediated by TGF-β1. This was confirmed by pre-treatment with TGF-β1 neutralizing antibody, which abolished the FCM-induced changes in both INa and Ito. In current-clamp experiments TGF-β1 (10 ng/ml) prolonged the action potential duration at 30, 50, and 90 repolarization (p<0.05); at 50 ng/ml it gave rise to early afterdepolarizations. In voltage-clamp experiments, TGF-β1 increased INa density in a dose-dependent manner without affecting voltage dependence of activation or inactivation. INa density was −36.25±2.8 pA/pF in control, −59.17±6.2 pA/pF at 0.1 ng/ml (p<0.01), and −58.22±6.6 pA/pF at 1 ng/ml (p<0.01). In sharp contrast, Ito density decreased from 22.2±1.2 pA/pF to 12.7±0.98 pA/pF (p<0.001) at 10 ng/ml. At 1 ng/ml TGF-β1 significantly increased SCN5A (NaV1.5) (+73%; p<0.01), while reducing KCNIP2 (Kchip2; −77%; p<0.01) and KCND2 (KV4.2; −50% p<0.05) mRNA levels. Further, the TGF-β1-induced increase in INa was mediated through activation of the PI3K-AKT pathway via phosphorylation of FOXO1 (a negative regulator of SCN5A). TGF-β1 released by myofibroblasts differentially regulates transcription and function of the main cardiac sodium channel and of the channel responsible for the transient outward current. The results provide new mechanistic insight into the electrical remodeling associated with myocardial injury. PMID:23393573

  4. The case of the QRS-T angles versus QRST integral maps.

    Science.gov (United States)

    van Oosterom, Adriaan

    2014-01-01

    This contribution discusses the QRS-T angle as well as the QRST integral map. Both of these topics have been tested in their application in extracting the major features of depolarization and repolarization: their spatio-temporal behaviour, and how much of their global or local nature might be deduced from signals that can be observed clinically. Recently, it is in particular the QRS-T angle that has received considerable attention, a method that stems directly from vectorcardiography, a subdomain of electrocardiography. The QRST integral map is a display of a map on the body surface of the integrals over time of the ECG signals observed at sets of electrodes. The common biophysical background of both techniques is highlighted. In particular it is explained why, in healthy myocardium, both provide a similar view on the global timing of the depolarization and repolarization of all cardiac myocytes, more specifically, on the dispersion of their action potential durations. In the presence of ischemia, the view obtained is of the integral over time of the transmembrane potentials, which comprises a 'mixture' of their timing and magnitude. The analysis of results of a simulation study emphasizes the large discrepancies that may be observed between the QRS-T angle in the frontal plane and its 3D variant. It is shown that the required vector representation of the signals may be derived from the 12-lead ECG by using the transfer matrix proposed in 1990 by Kors and colleagues.

  5. Instability of spiral and scroll waves in the presence of a gradient in the fibroblast density: the effects of fibroblast-myocyte coupling

    CERN Document Server

    Zimik, Soling

    2016-01-01

    Fibroblast-myocyte coupling can modulate electrical-wave dynamics in cardiac tissue. In diseased hearts, the distribution of fibroblasts is heterogeneous, so there can be gradients in the fibroblast density (henceforth we call this GFD) especially from highly injured regions, like infarcted or ischemic zones, to less-wounded regions of the tissue. Fibrotic hearts are known to be prone to arrhythmias, so it is important to understand the effects of GFD in the formation and sustenance of arrhythmic re- entrant waves, like spiral or scroll waves. Therefore, we investigate the effects of GFD on the stability of spiral and scroll waves of electrical activation in a state-of-the- art mathematical model for cardiac tissue in which we also include fibroblasts. By introducing GFD in controlled ways, we show that spiral and scroll waves can be unstable in the presence of GFDs because of regions with varying spiral or scroll-wave frequency {\\omega}, induced by the GFD. We examine the effects of the resting membrane pote...

  6. Dual-phase cardiac diffusion tensor imaging with strain correction.

    Directory of Open Access Journals (Sweden)

    Christian T Stoeck

    Full Text Available In this work we present a dual-phase diffusion tensor imaging (DTI technique that incorporates a correction scheme for the cardiac material strain, based on 3D myocardial tagging.In vivo dual-phase cardiac DTI with a stimulated echo approach and 3D tagging was performed in 10 healthy volunteers. The time course of material strain was estimated from the tagging data and used to correct for strain effects in the diffusion weighted acquisition. Mean diffusivity, fractional anisotropy, helix, transverse and sheet angles were calculated and compared between systole and diastole, with and without strain correction. Data acquired at the systolic sweet spot, where the effects of strain are eliminated, served as a reference.The impact of strain correction on helix angle was small. However, large differences were observed in the transverse and sheet angle values, with and without strain correction. The standard deviation of systolic transverse angles was significantly reduced from 35.9±3.9° to 27.8°±3.5° (p<0.001 upon strain-correction indicating more coherent fiber tracks after correction. Myocyte aggregate structure was aligned more longitudinally in systole compared to diastole as reflected by an increased transmural range of helix angles (71.8°±3.9° systole vs. 55.6°±5.6°, p<0.001 diastole. While diastolic sheet angle histograms had dominant counts at high sheet angle values, systolic histograms showed lower sheet angle values indicating a reorientation of myocyte sheets during contraction.An approach for dual-phase cardiac DTI with correction for material strain has been successfully implemented. This technique allows assessing dynamic changes in myofiber architecture between systole and diastole, and emphasizes the need for strain correction when sheet architecture in the heart is imaged with a stimulated echo approach.

  7. [Cardiac fibroma: A rare cause of sudden child death].

    Science.gov (United States)

    Humez, Sarah; Gibier, Jean-Baptiste; Recher, Morgan; Leteurtre, Stéphane; Leroy, Xavier; Devisme, Louise

    2015-10-01

    We report the case of a 3-year-old child who died from the consequences of a cardio-respiratory arrest despite reanimation procedures. Echocardiography and magnetic resonance imaging (MRI) revealed a mass of the free wall of the left ventricle. Autopsy confirmed the existence of a solitary myocardial tumor, well-circumscribed, firm, with a whitish and trabeculated cut surface. Histologically, the tumor consisted of bundles of spindle-shaped and regular cells mingling with collagen and elastic fibers, insinuating themselves between myocytes in periphery. Calcifications were present. After immunohistochemistry, the cells were highlighted by anti-actin smooth muscle antibody; but they were not highlighted by anti-desmin, anti-β catenin and anti-Ki67 antibodies. The diagnosis of cardiac fibroma was made. The primary cardiac tumors of child are rare and usually benign. They are essentially represented by rhabdomyoma and fibroma. Cardiac fibroma mostly occurs during the first year of life. It can be revealed by cardiac insufficiency, arrhythmia, chest pain or sudden death.

  8. AVE 0991 attenuates cardiac hypertrophy through reducing oxidative stress.

    Science.gov (United States)

    Ma, Yuedong; Huang, Huiling; Jiang, Jingzhou; Wu, Lingling; Lin, Chunxi; Tang, Anli; Dai, Gang; He, Jiangui; Chen, Yili

    2016-06-10

    AVE 0991, the nonpeptide angiotensin-(1-7) (Ang-(1-7)) analog, is recognized as having beneficial cardiovascular effects. However, the mechanisms have not been fully elucidated. This study was designed to investigate the effects of AVE 0991 on cardiac hypertrophy and the mechanisms involved. Mice were underwent aortic banding to induce cardiac hypertrophy followed by the administration of AVE 0991 (20 mg kg·day (-1)) for 4 weeks. It was shown that AVE 0991 reduced left ventricular hypertrophy and improved heart function, characterized by decreases in left ventricular weight and left ventricular end-diastolic diameter, and increases in ejection fraction. Moreover, AVE 0991 significantly down-regulated mean myocyte diameter and attenuate the gene expression of the hypertrophic markers. Furthermore, AVE 0991 inhibited the expression of NOX 2 and NOX 4, meaning that AVE 0991 reduced oxidative stress of cardiac hypertrophy mice. Our data showed that AVE 0991 treatment could attenuate cardiac hypertrophy and improve heart function, which may be due to reduce oxidative stress.

  9. Integration

    DEFF Research Database (Denmark)

    Emerek, Ruth

    2004-01-01

    Bidraget diskuterer de forskellige intergrationsopfattelse i Danmark - og hvad der kan forstås ved vellykket integration......Bidraget diskuterer de forskellige intergrationsopfattelse i Danmark - og hvad der kan forstås ved vellykket integration...

  10. Acidosis-induced p38 MAPK activation and its implication in regulation of cardiac contractility

    Institute of Scientific and Technical Information of China (English)

    Ming ZHENG; Rong HOU; Rui-ping XIAO

    2004-01-01

    AIM: To determine the possible role of pH in mediating activation of p38 mitogen-activated protein kinase (MAPK) and the consequent function of activated p38 MAPK in regulating cardiac contractility. METHODS: Adult rat cardiomyocytes were isolated and cultured. Low pH media was used to induce intracellular acidosis and contraction of single cardiomyocyte was measured. RESULTS: Phosphorylation of p38 MAPK was increased during ischemia, and pHi was decreased. Intracellular acidosis activated p38 MAPK to a similar level as ischemia. Inhibition of p38 MAPK activation by SB203580, a specific inhibitor of p38 MAPK, reversed acidosis-mediated reduction of myocyte contractility. CONCLUSION: In adult rat cardiomyocytes, intracellular acidification activated p38 MAPK and decreased cardiac contractility. Pretreatment of cardiomyocytes with SB203580 completely blocked p38 MAPK activation and partially reversed acidosis-mediated decline of cardiac contractility.

  11. Effects of phytoestrogens on protein turnover in rainbow trout primary myocytes

    Science.gov (United States)

    Soybean-derived ingredients used in aquaculture feeds may contain phytoestrogens, but it is unknown if these compounds can mimic the catabolic effects of estradiol in fish muscle. Six day-old rainbow trout primary myocytes were exposed to increasing concentrations (10 nM – 100 µM) of either geniste...

  12. Effects of cannabidiol on contractions and calcium signaling in rat ventricular myocytes.

    Science.gov (United States)

    Ali, Ramez M; Al Kury, Lina T; Yang, Keun-Hang Susan; Qureshi, Anwar; Rajesh, Mohanraj; Galadari, Sehamuddin; Shuba, Yaroslav M; Howarth, Frank Christopher; Oz, Murat

    2015-04-01

    Cannabidiol (CBD), a major nonpsychotropic cannabinoid found in Cannabis plant, has been shown to influence cardiovascular functions under various physiological and pathological conditions. In the present study, the effects of CBD on contractility and electrophysiological properties of rat ventricular myocytes were investigated. Video edge detection was used to measure myocyte shortening. Intracellular Ca(2+) was measured in cells loaded with the Ca(2+) sensitive fluorescent indicator fura-2 AM. Whole-cell patch clamp was used to measure action potential and Ca(2+) currents. Radioligand binding was employed to study pharmacological characteristics of CBD binding. CBD (1μM) caused a significant decrease in the amplitudes of electrically evoked myocyte shortening and Ca(2+) transients. However, the amplitudes of caffeine-evoked Ca(2+) transients and the rate of recovery of electrically evoked Ca(2+) transients following caffeine application were not altered. CBD (1μM) significantly decreased the duration of APs. Further studies on L-type Ca(2+) channels indicated that CBD inhibits these channels with IC50 of 0.1μM in a voltage-independent manner. Radioligand studies indicated that the specific binding of [(3)H]Isradipine, was not altered significantly by CBD. The results suggest that CBD depresses myocyte contractility by suppressing L-type Ca(2+) channels at a site different than dihydropyridine binding site and inhibits excitation-contraction coupling in cardiomyocytes.

  13. Sarcolemmal Ca(2+)-entry through L-type Ca(2+) channels controls the profile of Ca(2+)-activated Cl(-) current in canine ventricular myocytes.

    Science.gov (United States)

    Horváth, Balázs; Váczi, Krisztina; Hegyi, Bence; Gönczi, Mónika; Dienes, Beatrix; Kistamás, Kornél; Bányász, Tamás; Magyar, János; Baczkó, István; Varró, András; Seprényi, György; Csernoch, László; Nánási, Péter P; Szentandrássy, Norbert

    2016-08-01

    Ca(2+)-activated Cl(-) current (ICl(Ca)) mediated by TMEM16A and/or Bestrophin-3 may contribute to cardiac arrhythmias. The true profile of ICl(Ca) during an actual ventricular action potential (AP), however, is poorly understood. We aimed to study the profile of ICl(Ca) systematically under physiological conditions (normal Ca(2+) cycling and AP voltage-clamp) as well as in conditions designed to change [Ca(2+)]i. The expression of TMEM16A and/or Bestrophin-3 in canine and human left ventricular myocytes was examined. The possible spatial distribution of these proteins and their co-localization with Cav1.2 was also studied. The profile of ICl(Ca), identified as a 9-anthracene carboxylic acid-sensitive current under AP voltage-clamp conditions, contained an early fast outward and a late inward component, overlapping early and terminal repolarizations, respectively. Both components were moderately reduced by ryanodine, while fully abolished by BAPTA, but not EGTA. [Ca(2+)]i was monitored using Fura-2-AM. Setting [Ca(2+)]i to the systolic level measured in the bulk cytoplasm (1.1μM) decreased ICl(Ca), while application of Bay K8644, isoproterenol, and faster stimulation rates increased the amplitude of ICl(Ca). Ca(2+)-entry through L-type Ca(2+) channels was essential for activation of ICl(Ca). TMEM16A and Bestrophin-3 showed strong co-localization with one another and also with Cav1.2 channels, when assessed using immunolabeling and confocal microscopy in both canine myocytes and human ventricular myocardium. Activation of ICl(Ca) in canine ventricular cells requires Ca(2+)-entry through neighboring L-type Ca(2+) channels and is only augmented by SR Ca(2+)-release. Substantial activation of ICl(Ca) requires high Ca(2+) concentration in the dyadic clefts which can be effectively buffered by BAPTA, but not EGTA.

  14. Regression of cardiac hypertrophy in the SHR by combined renin-angiotensin system blockade and dietary sodium restriction

    Directory of Open Access Journals (Sweden)

    Emad Abro

    2001-03-01

    Full Text Available Altered operation of the renin-angiotensin-aldosterone system (RAAS and dietary sodium intake have been identified as independent risk factors for cardiac hypertrophy. The way in which sodium intake and the operation of the renin-angiotensin-aldosterone system interact in the pathogenesis of cardiac hypertrophy is poorly understood. The aims of this study were to investigate the cardiac effects of the renin-angiotensin system (RAS blockade in the spontaneously hypertensive rat (SHR, using co-treatment with an angiotensin II receptor blocker (ARB and an angiotensin-converting enzyme (ACE inhibitor with different sodium intakes. Our experiments with SHR show that, at high levels of sodium intake (4.0%, aggressive RAS blockade treatment with candesartan (3 mg/kg and perindopril (6 mg/kg does not result in regression of cardiac hypertrophy. In contrast, RAS blockade coupled with reduced sodium diet (0.2% significantly regresses cardiac hypertrophy, impairs animal growth and is associated with elevated plasma renin and dramatically suppressed plasma angiotensinogen levels. Histological analyses indicate that the differential effect of reduced sodium on heart growth during RAS blockade is not associated with any change in myocardial interstitial collagen, but reflects modification of cellular geometry. Dimensional measurements of enzymatically-isolated ventricular myocytes show that, in the RAS blocked, reduced sodium group, myocyte length and width were decreased by about 16—19% compared with myocytes from the high sodium treatment group. Our findings highlight the importance of `titrating' sodium intake with combined RAS blockade in the clinical setting to optimise therapeutic benefit.

  15. Excavatolide B Modulates the Electrophysiological Characteristics and Calcium Homeostasis of Atrial Myocytes

    Directory of Open Access Journals (Sweden)

    Hwong-Ru Hwang

    2017-01-01

    Full Text Available Severe bacterial infections caused by sepsis always result in profound physiological changes, including fever, hypotension, arrhythmia, necrosis of tissue, systemic multi-organ dysfunction, and finally death. The lipopolysaccharide (LPS provokes an inflammatory response under sepsis, which may increase propensity to arrhythmogenesis. Excavatolide B (EXCB possesses potent anti-inflammatory effects. However, it is not clear whether EXCB could modulate the electrophysiological characteristics and calcium homeostasis of atrial myocytes. This study investigated the effects of EXCB on the atrial myocytes exposed to lipopolysaccharide. A whole-cell patch clamp and indo-1 fluorimetric ratio technique was employed to record the action potential (AP, ionic currents, and intracellular calcium ([Ca2+]i in single, isolated rabbit left atrial (LA cardiomyocytes, with and without LPS (1 μg/mL and LPS + EXCB administration (10 μM for 6 ± 1 h, in order to investigate the role of EXCB on atrial electrophysiology. In the presence of LPS, EXCB-treated LA myocytes (n = 13 had a longer AP duration at 20% (29 ± 2 vs. 20 ± 2 ms, p < 0.05, 50% (52 ± 4 vs. 40 ± 3 ms, p < 0.05, and 90% (85 ± 5 vs. 68 ± 3 ms, p < 0.05, compared to the LPS-treated cells (n = 12. LPS-treated LA myocytes showed a higher late sodium current, Na+/Ca2+ exchanger current, transient outward current, and delayed rectifier potassium current, but a lower l-type Ca2+ current, than the control LA myocytes. Treatment with EXCB reversed the LPS-induced alterations of the ionic currents. LPS-treated, EXCB-treated, and control LA myocytes exhibited similar Na+ currents. In addition, the LPS-treated LA myocytes exhibited a lower [Ca2+]i content and higher sarcoplasmic reticulum calcium content, than the controls. EXCB reversed the LPS-induced calcium alterations. In conclusion, EXCB modulates LPS-induced LA electrophysiological characteristics and calcium homeostasis, which may contribute to

  16. Excavatolide B Modulates the Electrophysiological Characteristics and Calcium Homeostasis of Atrial Myocytes

    Science.gov (United States)

    Hwang, Hwong-Ru; Tai, Buh-Yuan; Cheng, Pao-Yun; Chen, Ping-Nan; Sung, Ping-Jyun; Wen, Zhi-Hong; Hsu, Chih-Hsueng

    2017-01-01

    Severe bacterial infections caused by sepsis always result in profound physiological changes, including fever, hypotension, arrhythmia, necrosis of tissue, systemic multi-organ dysfunction, and finally death. The lipopolysaccharide (LPS) provokes an inflammatory response under sepsis, which may increase propensity to arrhythmogenesis. Excavatolide B (EXCB) possesses potent anti-inflammatory effects. However, it is not clear whether EXCB could modulate the electrophysiological characteristics and calcium homeostasis of atrial myocytes. This study investigated the effects of EXCB on the atrial myocytes exposed to lipopolysaccharide. A whole-cell patch clamp and indo-1 fluorimetric ratio technique was employed to record the action potential (AP), ionic currents, and intracellular calcium ([Ca2+]i) in single, isolated rabbit left atrial (LA) cardiomyocytes, with and without LPS (1 μg/mL) and LPS + EXCB administration (10 μM) for 6 ± 1 h, in order to investigate the role of EXCB on atrial electrophysiology. In the presence of LPS, EXCB-treated LA myocytes (n = 13) had a longer AP duration at 20% (29 ± 2 vs. 20 ± 2 ms, p < 0.05), 50% (52 ± 4 vs. 40 ± 3 ms, p < 0.05), and 90% (85 ± 5 vs. 68 ± 3 ms, p < 0.05), compared to the LPS-treated cells (n = 12). LPS-treated LA myocytes showed a higher late sodium current, Na+/Ca2+ exchanger current, transient outward current, and delayed rectifier potassium current, but a lower l-type Ca2+ current, than the control LA myocytes. Treatment with EXCB reversed the LPS-induced alterations of the ionic currents. LPS-treated, EXCB-treated, and control LA myocytes exhibited similar Na+ currents. In addition, the LPS-treated LA myocytes exhibited a lower [Ca2+]i content and higher sarcoplasmic reticulum calcium content, than the controls. EXCB reversed the LPS-induced calcium alterations. In conclusion, EXCB modulates LPS-induced LA electrophysiological characteristics and calcium homeostasis, which may contribute to attenuating

  17. Cardiac Niche Influences the Direct Reprogramming of Canine Fibroblasts into Cardiomyocyte-Like Cells

    Directory of Open Access Journals (Sweden)

    Giacomo Palazzolo

    2016-01-01

    Full Text Available The Duchenne and Becker muscular dystrophies are caused by mutation of dystrophin gene and primarily affect skeletal and cardiac muscles. Cardiac involvement in dystrophic GRMD dogs has been demonstrated by electrocardiographic studies with the onset of a progressive cardiomyopathy similar to the cardiac disease in DMD patients. In this respect, GRMD is a useful model to explore cardiac and skeletal muscle pathogenesis and for developing new therapeutic protocols. Here we describe a protocol to convert GRMD canine fibroblasts isolated from heart and skin into induced cardiac-like myocytes (ciCLMs. We used a mix of transcription factors (GATA4, HAND2, TBX5, and MEF2C, known to be able to differentiate mouse and human somatic cells into ciCLMs. Exogenous gene expression was obtained using four lentiviral vectors carrying transcription factor genes and different resistance genes. Our data demonstrate a direct switch from fibroblast into ciCLMs with no activation of early cardiac genes. ciCLMs were unable to contract spontaneously, suggesting, differently from mouse and human cells, an incomplete differentiation process. However, when transplanted in neonatal hearts of SCID/Beige mice, ciCLMs participate in cardiac myogenesis.

  18. miR-1 exacerbates cardiac ischemia-reperfusion injury in mouse models.

    Directory of Open Access Journals (Sweden)

    Zhenwei Pan

    Full Text Available Recent studies have revealed the critical role of microRNAs (miRNAs in regulating cardiac injury. Among them, the cardiac enriched microRNA-1(miR-1 has been extensively investigated and proven to be detrimental to cardiac myocytes. However, solid in vivo evidence for the role of miR-1 in cardiac injury is still missing and the potential therapeutic advantages of systemic knockdown of miR-1 expression remained unexplored. In this study, miR-1 transgenic (miR-1 Tg mice and locked nucleic acid modified oligonucleotide against miR-1 (LNA-antimiR-1 were used to explore the effects of miR-1 on cardiac ischemia/reperfusion injury (30 min ischemia followed by 24 h reperfusion. The cardiac miR-1 level was significantly increased in miR-1 Tg mice, and suppressed in LNA-antimiR-1 treated mice. When subjected to ischemia/reperfusion injury, miR-1 overexpression exacerbated cardiac injury, manifested by increased LDH, CK levels, caspase-3 expression, apoptosis and cardiac infarct area. On the contrary, LNA-antimiR-1 treatment significantly attenuated cardiac ischemia/reperfusion injury. The expression of PKCε and HSP60 was significantly repressed by miR-1 and enhanced by miR-1 knockdown, which may be a molecular mechanism for the role miR-1 in cardiac injury. Moreover, luciferase assay confirmed the direct regulation of miR-1 on protein kinase C epsilon (PKCε and heat shock protein 60 (HSP60. In summary, this study demonstrated that miR-1 is a causal factor for cardiac injury and systemic LNA-antimiR-1 therapy is effective in ameliorating the problem.

  19. -Adrenergic receptors on rat ventricular myocytes: characteristics and linkage to cAMP metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Buxton, I.L.O.; Brunton, L.L.

    1986-08-01

    When incubated with purified cardiomyocytes from adult rat ventricle, the 1-antagonist (TH)prazosin binds to a single class of sites with high affinity. Competition for (TH)prazosin binding by the 2-selective antagonist yohimbine and the nonselective -antagonist phentolamine demonstrates that these receptors are of the 1-subtype. In addition, incubation of myocyte membranes with (TH)yohimbine results in no measurable specific binding. Agonist competition for (TH)prazosin binding to membranes prepared from purified myocytes demonstrates the presence of two components of binding: 28% of 1-receptors interact with norepinephrine with high affinity (K/sub D/ = 36 nM), whereas the majority of receptors (72%) have a low affinity for agonist (K/sub D/ = 2.2 M). After addition of 10 M GTP, norepinephrine competes for (TH)prazosin binding to a single class of sites with lower affinity (K/sub D/ = 2.2 M). Incubation of intact myocytes for 2 min with 1 M norepinephrine leads to significantly less cyclic AMP (cAMP) accumulation than stimulation with either norepinephrine plus prazosin or isoproterenol. Likewise, incubation of intact myocytes with 10 W M norepinephrine leads to significantly less activation of cAMP-dependent protein kinase than when myocytes are stimulated by both norepinephrine and the 1-adrenergic antagonist, prazosin or the US -adrenergic agonist, isoproterenol. They conclude that the cardiomyocyte 1 receptor is coupled to a guanine nucleotide-binding protein, that 1-receptors are functionally linked to decreased intracellular cAMP content, and that this change in cellular cAMP is expressed as described activation of cAMP-dependent protein kinase.

  20. [Research progress of cardiac systems biology].

    Science.gov (United States)

    Wang, Juan; Shang, Tong

    2009-04-01

    Systems Biology is one of the most widely discussed fields among emerging post-genomic disciplines. Medical systems biology is an important component of systems biology. The goals of medical systems biology are gaining a complete understanding of human body in normal and disease states. Driven by the great importance of cardiovascular diseases, cardiac systems biology is improving rapidly. This review provides an overview of major themes in the developing field of cardiac systems biology, including some of the high-throughput experiments and strategies used to integrate the datasets, various types of computational approaches used for developing useful quantitative models, and successful examples, future directions of cardiac systems biology.

  1. Danhong injection attenuates cardiac injury induced by ischemic and reperfused neuronal cells through regulating arginine vasopressin expression and secretion.

    Science.gov (United States)

    Yang, Mingzhu; Orgah, John; Zhu, Jie; Fan, Guanwei; Han, Jihong; Wang, Xiaoying; Zhang, Boli; Zhu, Yan

    2016-07-01

    Ischemic stroke is associated with cardiac myocyte vulnerability through some unknown mechanisms. Arginine vasopressin (AVP) may exert considerable function in the relationship of brain damage and heart failure. Danhong injection (DHI) can protect both stroke and heart failure patients with good efficacy in clinics. The aim of this study is to investigate the mechanism of DHI in heart and brain co-protection effects to determine whether AVP plays key role in this course. In the present study, we found that both the supernatant from oxygen-glucose deprivation (OGD) and reperfused primary rat neuronal cells (PRNCs) and AVP treatment caused significant reduction in cell viability and mitochondrial activity in primary rat cardiac myocytes (RCMs). Besides, DHI had the same protective effects with conivaptan, a dual vasopressin V1A and V2 receptor antagonist, in reducing the RCM damage induced by overdose AVP. DHI significantly decreased the injury of both PRNCs and RCMs. Meanwhile, the AVP level was elevated dramatically in OGD and reperfusion PRNCs, and DHI was able to decrease the AVP expression in the injured PRNCs. Therefore, our present results suggested that OGD and reperfusion PRNCs might induce myocyte injury by elevating the AVP expression in PRNCs. The ability of DHI to reinstate AVP level may be one of the mechanisms of its brain and heart co-protection effects.

  2. Cardiac tamponade (image)

    Science.gov (United States)

    Cardiac tamponade is a condition involving compression of the heart caused by blood or fluid accumulation in the space ... they cannot adequately fill or pump blood. Cardiac tamponade is an emergency condition that requires hospitalization.

  3. What Is Cardiac Rehabilitation?

    Science.gov (United States)

    ANSWERS by heart Treatments + Tests What Is Cardiac Rehabilitation? A cardiac rehabilitation (rehab) program takes place in a hospital or ... special help in making lifestyle changes. During your rehabilitation program you’ll… • Have a medical evaluation to ...

  4. Rhabdomyosarcoma cells show an energy producing anabolic metabolic phenotype compared with primary myocytes

    Directory of Open Access Journals (Sweden)

    Higashi Richard M

    2008-10-01

    Full Text Available Abstract Background The functional status of a cell is expressed in its metabolic activity. We have applied stable isotope tracing methods to determine the differences in metabolic pathways in proliferating Rhabdomysarcoma cells (Rh30 and human primary myocytes in culture. Uniformly 13C-labeled glucose was used as a source molecule to follow the incorporation of 13C into more than 40 marker metabolites using NMR and GC-MS. These include metabolites that report on the activity of glycolysis, Krebs' cycle, pentose phosphate pathway and pyrimidine biosynthesis. Results The Rh30 cells proliferated faster than the myocytes. Major differences in flux through glycolysis were evident from incorporation of label into secreted lactate, which accounts for a substantial fraction of the glucose carbon utilized by the cells. Krebs' cycle activity as determined by 13C isotopomer distributions in glutamate, aspartate, malate and pyrimidine rings was considerably higher in the cancer cells than in the primary myocytes. Large differences were also evident in de novo biosynthesis of riboses in the free nucleotide pools, as well as entry of glucose carbon into the pyrimidine rings in the free nucleotide pool. Specific labeling patterns in these metabolites show the increased importance of anaplerotic reactions in the cancer cells to maintain the high demand for anabolic and energy metabolism compared with the slower growing primary myocytes. Serum-stimulated Rh30 cells showed higher degrees of labeling than serum starved cells, but they retained their characteristic anabolic metabolism profile. The myocytes showed evidence of de novo synthesis of glycogen, which was absent in the Rh30 cells. Conclusion The specific 13C isotopomer patterns showed that the major difference between the transformed and the primary cells is the shift from energy and maintenance metabolism in the myocytes toward increased energy and anabolic metabolism for proliferation in the Rh30 cells

  5. Taxifolin protects against cardiac hypertrophy and fibrosis during biomechanical stress of pressure overload

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Haipeng; Zhang, Xin [Department of Critical Care Medicine, Qilu Hospital of Shandong University, Jinan (China); Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital of Shandong University, Jinan (China); Cui, Yuqian [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital of Shandong University, Jinan (China); Zhou, Heng [Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan (China); Xu, Dachun [Department of Cardiology, Shanghai Tenth People' s Hospital of Tongji University, Shanghai (China); Shan, Tichao; Zhang, Fan [Department of Critical Care Medicine, Qilu Hospital of Shandong University, Jinan (China); Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital of Shandong University, Jinan (China); Guo, Yuan [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital of Shandong University, Jinan (China); Chen, Yuguo, E-mail: chen919085@163.com [Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital of Shandong University, Jinan (China); Department of Emergency, Qilu Hospital of Shandong University, Jinan (China); Wu, Dawei, E-mail: wdwu55@163.com [Department of Critical Care Medicine, Qilu Hospital of Shandong University, Jinan (China); Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital of Shandong University, Jinan (China)

    2015-09-01

    Cardiac hypertrophy is a key pathophysiological component to biomechanical stress, which has been considered to be an independent and predictive risk factor for adverse cardiovascular events. Taxifolin (TAX) is a typical plant flavonoid, which has long been used clinically for treatment of cardiovascular and cerebrovascular diseases. However, very little is known about whether TAX can influence the development of cardiac hypertrophy. In vitro studies, we found that TAX concentration-dependently inhibited angiotensin II (Ang II) induced hypertrophy and protein synthesis in cardiac myocytes. Then we established a mouse model by transverse aortic constriction (TAC) to further confirm our findings. It was demonstrated that TAX prevented pressure overload induced cardiac hypertrophy in mice, as assessed by ventricular mass/body weight, echocardiographic parameters, myocyte cross-sectional area, and the expression of ANP, BNP and β-MHC. The excess production of reactive oxygen species (ROS) played critical role in the development of cardiac hypertrophy. TAX arrested oxidative stress and decreased the expression of 4-HNE induced by pressure overload. Moreover, TAX negatively modulated TAC-induced phosphorylation of ERK1/2 and JNK1/2. Further studies showed that TAX significantly attenuated left ventricular fibrosis and collagen synthesis through abrogating the phosphorylation of Smad2 and Smad2/3 nuclear translocation. These results demonstrated that TAX could inhibit cardiac hypertrophy and attenuate ventricular fibrosis after pressure overload. These beneficial effects were at least through the inhibition of the excess production of ROS, ERK1/2, JNK1/2 and Smad signaling pathways. Therefore, TAX might be a potential candidate for the treatment of cardiac hypertrophy and fibrosis. - Highlights: • We focus on the protective effect of taxifolin on cardiac remodeling. • Taxifolin inhibited cardiac hypertrophy and attenuated ventricular fibrosis. • Taxifolin

  6. Cardiac sodium channelopathies

    NARCIS (Netherlands)

    Amin, A.S.; Asghari-Roodsari, A.; Tan, H.L.

    2010-01-01

    Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward depolarizing current (I-Na) during phase 0 of the cardiac action potential. The importance of I-Na for normal cardiac electrical activity is reflected by the high incidence of

  7. ROLE OF ALPHA-ADRENERGIC BLOCKING AGENT IN HYPERTROPHY OF CARDIAC MYOCYTE CARDIAC MYOCYTE%α受体阻滞剂对心肌细胞肥大的作用

    Institute of Scientific and Technical Information of China (English)

    谢协驹; 吉丽敏; 符史干

    2001-01-01

    objective:The present study was to investigate the role of alphal-adrenergic receptor blocking agent(phentolamine) in the hypertrophy of cardiaomyocyte induced by adrenaline.Methods:The measurement of cell surface area and[3H]-Leucine incorporation judged the hypertrophy of cardiaomyocyte in cultured neonatal rat myocardal cells,Results:The results showed that adrenaline could significantly increase cell.surface area promote[3H]-Leucine incorporation.Alphal-adrenergic blocking agent could markedly block effects of adrenaline increasing cell surface area and promoting [3H]-Leucine incorporation, Conclusions:These results suggest that alpha-adrenergic blocking agent can prevent the hypertrophy of cardiomyocytes induced by adrenaline in cultured neontal rat myocardal cells.%目的:观察α受体阻滞剂酚妥拉明对肾上腺素诱导的心肌细胞肥大的作用。方法:在培养新生大鼠心肌细胞上。通过测量心肌细胞表面积和[3H]-Leu的掺入量来判断心肌细胞肥大。结果:肾上腺素要明显增加心肌细胞表面和[3H]-亮氨酸([3H-Leu]的掺入量,α受体阻滞剂酚妥拉明能阻断肾上腺素增加心肌细胞表面积和[3H]-Leu掺入量的作用。结论:α受体阻滞有减轻肾上腺素诱导心肌细胞肥大的作用。

  8. Cardiac Fibroblasts Aggravate Viral Myocarditis: Cell Specific Coxsackievirus B3 Replication

    Directory of Open Access Journals (Sweden)

    Diana Lindner

    2014-01-01

    Full Text Available Myocarditis is an inflammatory disease caused by viral infection. Different subpopulations of leukocytes enter the cardiac tissue and lead to severe cardiac inflammation associated with myocyte loss and remodeling. Here, we study possible cell sources for viral replication using three compartments of the heart: fibroblasts, cardiomyocytes, and macrophages. We infected C57BL/6j mice with Coxsackievirus B3 (CVB3 and detected increased gene expression of anti-inflammatory and antiviral cytokines in the heart. Subsequently, we infected cardiac fibroblasts, cardiomyocytes, and macrophages with CVB3. Due to viral infection, the expression of TNF-α, IL-6, MCP-1, and IFN-β was significantly increased in cardiac fibroblasts compared to cardiomyocytes or macrophages. We found that in addition to cardiomyocytes cardiac fibroblasts were infected by CVB3 and displayed a higher virus replication (132-fold increase compared to cardiomyocytes (14-fold increase between 6 and 24 hours after infection. At higher virus concentrations, macrophages are able to reduce the viral copy number. At low virus concentration a persistent virus infection was determined. Therefore, we suggest that cardiac fibroblasts play an important role in the pathology of CVB3-induced myocarditis and are another important contributor of virus replication aggravating myocarditis.

  9. Erythropoietin protects myocardin-expressing cardiac stem cells against cytotoxicity of tumor necrosis factor-{alpha}

    Energy Technology Data Exchange (ETDEWEB)

    Madonna, Rosalinda [The Center for Cardiovascular Biology and Atherosclerosis Research, The University of Texas Health Science Center at Houston, Texas (United States); Institute of Cardiology, and Center of Excellence on Aging, ' G. d' Annunzio' University, Chieti (Italy); Shelat, Harnath; Xue, Qun; Willerson, James T. [The Center for Cardiovascular Biology and Atherosclerosis Research, The University of Texas Health Science Center at Houston, Texas (United States); The Texas Heart Institute at St. Luke' s Episcopal Hospital, Houston, Texas (United States); De Caterina, Raffaele [Institute of Cardiology, and Center of Excellence on Aging, ' G. d' Annunzio' University, Chieti (Italy); Geng, Yong-Jian, E-mail: yong-jian.geng@uth.tmc.edu [The Center for Cardiovascular Biology and Atherosclerosis Research, The University of Texas Health Science Center at Houston, Texas (United States); The Texas Heart Institute at St. Luke' s Episcopal Hospital, Houston, Texas (United States)

    2009-10-15

    Cardiac stem cells are vulnerable to inflammation caused by infarction or ischemic injury. The growth factor, erythropoietin (Epo), ameliorates the inflammatory response of the myocardium to ischemic injury. This study was designed to assess the role of Epo in regulation of expression and activation of the cell death-associated intracellular signaling components in cardiac myoblasts stimulated with the proinflammatory cytokine tumor necrosis factor (TNF)-{alpha}. Cardiac myoblasts isolated from canine embryonic hearts characterized by expression of myocardin A, a promyogenic transcription factor for cardiovascular muscle development were pretreated with Epo and then exposed to TNF-{alpha}. Compared to untreated cells, the Epo-treated cardiac myoblasts exhibited better morphology and viability. Immunoblotting revealed lower levels of active caspase-3 and reductions in iNOS expression and NO production in Epo-treated cells. Furthermore, Epo pretreatment reduced nuclear translocation of NF-{kappa}B and inhibited phosphorylation of inhibitor of kappa B (I{kappa}B) in TNF-{alpha}-stimulated cardiac myoblasts. Thus, Epo protects cardiac myocyte progenitors or myoblasts against the cytotoxic effects of TNF-{alpha} by inhibiting NF-{kappa}B-mediated iNOS expression and NO production and by preventing caspase-3 activation.

  10. Cardiac Atrophy and Diastolic Dysfunction During and After Long Duration Spaceflight: Functional Consequences for Orthostatic Intolerance, Exercise Capability and Risk for Cardiac Arrhythmias

    Science.gov (United States)

    Levine, Benjamin D.; Bungo, Michael W.; Platts, Steven H.; Hamilton, Douglas R.; Johnston, Smith L.

    2009-01-01

    Cardiac Atrophy and Diastolic Dysfunction During and After Long Duration Spaceflight: Functional Consequences for Orthostatic Intolerance, Exercise Capability and Risk for Cardiac Arrhythmias (Integrated Cardiovascular) will quantify the extent of long-duration space flightassociated cardiac atrophy (deterioration) on the International Space Station crewmembers.

  11. EFFECT OF COXSACKIEVIRUS B3 ON ION CHANNEL CURRENTS IN RAT VENTRICULAR MYOCYTES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective. To investigate the effects of coxsackievims B3 (CVB3) on ion channel currents in rat ventricular my-Methods. Rat hearts were isolated with collagenase to acquire single ventricular myocytes, L-type voltnge-depen-dent calcium channel( VDCC)current (Ica), Na + current (INa), outward potassium current (Iout), inwardly rectifying potassium current(IKI) were recorded using whole cell patch clamp techniques. Results. CVB3 infection increased Ica and Iout, while decreased IKI; but it had no obvious effect on INa. Conclusion. Tne effects of CVB3 on Ica、 Iout、 IKI may be one of the mechanisms of myocytes damage and the oc-currence of abnormal electroactivities induced by CVB3 infection.

  12. Influence of the cardiac myosin hinge region on contractile activity.

    Science.gov (United States)

    Margossian, S S; Krueger, J W; Sellers, J R; Cuda, G; Caulfield, J B; Norton, P; Slayter, H S

    1991-06-01

    The participation of cardiac myosin hinge in contractility was investigated by in vitro motility and ATPase assays and by measurements of sarcomere shortening. The effect on contractile activity was analyzed using an antibody directed against a 20-amino acid peptide within the hinge region of myosin. This antibody bound specifically at the hinge at a distance of 55 nm from the S1/S2 junction, was specific to human, dog, and rat cardiac myosins, did not crossreact with gizzard or skeletal myosin, and had no effect on ATPase activity of purified S1 and myofibrils. However, it completely suppressed the movement of actin filaments in in vitro motility assays and reduced active shortening of sarcomeres of skinned cardiac myocytes by half. Suppression of motion by the anti-hinge antibody may reflect a mechanical constraint imposed by the antibody upon the mobility of the S2 region of myosin. The results suggest that the steps in the mechanochemical energy transduction can be separately influenced through S2.

  13. Influence of skeletal muscle satellite cells implanted into infarcted myocardium on remnant myocyte volumes

    Institute of Scientific and Technical Information of China (English)

    钟竑; 朱洪生; 卫洪超; 张臻

    2003-01-01

    Objective To study the effects of skeletal muscle satellite cells implanted into infarcted myocardium on the volume of remnant myocytes.Methods Thirty-six adult mongrel canines were divided randomly into implantation group and control group. In the implantation group, skeletal muscle satellite cells taken from the gluteus maximus muscles of the dogs were cultured, proliferated and labeled with 4', 6-diamidino-2-phenylindone (DAPI) in vitro. In both groups, a model of acute myocardial infarction was established in every dog. In the implantation group, each dog was injected with M199 solution containing autologous skeletal muscle satellite cells. The dogs in the control group received M199 solution without skeletal muscle satellite cells. The dogs of both groups were killed 2, 4 and 8 weeks after implantation (six dogs in a separate group each time). Both infarcted myocardium and normal myocytes distal from the infracted regions isolated were observed under optical and fluorescent microscope. Their volumes were determined using a confocal microscopy image analysis system and analyzed using SAS. A P<0.05 was considered significant.Results A portion of the implanted cells differentiated into muscle fiber with striations and were connected with intercalated discs. Cross-sectional area and cell volume were increased in normal myocardium. Hypertrophy of remnant myocytes in the infarcted site after skeletal muscle cell implantation was much more evident than in the control group. Cross-sectional area, cell area and cell volume differed significantly from those of the control group (P< 0.05). Hypertrophy of the cells occurred predominantly in terms of width and thickness, whereas cell length remained unchanged. Conclusion Skeletal muscle satellite cells implanted into infarct myocardium, could induce the hypertrophy of remnant myocyte cells in the infarcted site and could also aid in the recovery of the contractile force of the infarcted myocardium.

  14. Differential regulation of potassium currents by FGF-1 and FGF-2 in embryonic Xenopus laevis myocytes.

    Science.gov (United States)

    Chauhan-Patel, R; Spruce, A E

    1998-10-01

    1. Fibroblast growth factors (FGFs) are involved in the regulation of many aspects of muscle development. This study investigated their role in regulating voltage-dependent K+ currents in differentiating Xenopus laevis myocytes. Both FGF-1 and FGF-2 are expressed by developing muscle cells, so their actions were compared. Experiments were performed on cultured myocytes isolated from stage 15 embryos. 2. Long-term exposure of the embryonic myocytes to FGF-1 downregulated inward rectifier K+ current (IK(IR)) density as well as both sustained and inactivating voltage-dependent outward K+ currents (IK,S and IK,I, respectively) and their densities. In contrast, FGF-2 upregulated these currents, although, because of an increase in capacitance caused by FGF-2, current density did not change with this factor. 3. The regulation of IK(IR) by FGF-1 was prevented by the cytoplasmic tyrosine kinase inhibitor herbimycin A, but that of IK,S and IK,I was unaffected, indicating that FGF-1 achieves its regulatory effects on electrical development via separate signalling pathways. The receptor tyrosine kinase inhibitor genistein in isolation suppressed K+ currents, but this may have occurred through a channel-blocking mechanism. 4. In many cells, IK, S was found to be composed of two components with differing voltage dependencies of activation. The FGFs brought about an alteration in the amount of total IK,S by equal effects on each component. Conversely, herbimycin A increased the proportion of low voltage-activated current without affecting total current amplitude. Therefore, we suggest that a single species of channel whose voltage dependence is shifted by tyrosine phosphorylation generates IK,S. 5. In summary, FGF-1 and FGF-2 exert opposite effects on voltage-dependent K+ currents in embryonic myocytes and, furthermore, FGF-1 achieves its effects on different K+ currents via separate second messenger pathways.

  15. Heuristic problems in defining the three-dimensional arrangement of the ventricular myocytes.

    Science.gov (United States)

    Anderson, Robert H; Ho, Siew Yen; Sanchez-Quintana, Damian; Redmann, Klaus; Lunkenheimer, Paul P

    2006-06-01

    There is lack of consensus concerning the three-dimensional arrangement of the myocytes within the ventricular muscle masses. Bioengineers are seeking to model the structure of the heart. Although the success of such models depends on the accuracy of the anatomic evidence, most of them have been based on concepts that are far from anatomical reality, which ignore many significant previous accounts of anatomy presented over the past 400 years. During the 19th century, Pettigrew emphasized that the heart was built on the basis of a modified blood vessel rather than in the form of skeletal muscles. This fact was reemphasized by Lev and Simkins as well as Grant in the 20th century, but the caveats listed by these authors have been ignored by proponents of two current concepts, which state either that the myocardium is arranged in the form of a "unique myocardial band," or that the walls of the ventricles are sequestrated in uniform fashion by laminar sheets of fibrous tissue extending from epicardium to endocardium. These two concepts are themselves incompatible and are further at variance with the majority of anatomic studies, which have emphasized the regional heterogeneity to be found in the three-dimensional packing of the myocytes within a supporting matrix of fibrous tissue. We reemphasize the significance of this three-dimensional muscular mesh, showing how the presence of intruding aggregates of myocytes extending in oblique transmural fashion also contends against the notion that all myocytes are orientated with their long axes parallel to the epicardial and enodcardial surfaces.

  16. Mechanisms of cardiac pain.

    Science.gov (United States)

    Foreman, Robert D; Garrett, Kennon M; Blair, Robert W

    2015-04-01

    Angina pectoris is cardiac pain that typically is manifested as referred pain to the chest and upper left arm. Atypical pain to describe localization of the perception, generally experienced more by women, is referred to the back, neck, and/or jaw. This article summarizes the neurophysiological and pharmacological mechanisms for referred cardiac pain. Spinal cardiac afferent fibers mediate typical anginal pain via pathways from the spinal cord to the thalamus and ultimately cerebral cortex. Spinal neurotransmission involves substance P, glutamate, and transient receptor potential vanilloid-1 (TRPV1) receptors; release of neurokinins such as nuclear factor kappa b (NF-kb) in the spinal cord can modulate neurotransmission. Vagal cardiac afferent fibers likely mediate atypical anginal pain and contribute to cardiac ischemia without accompanying pain via relays through the nucleus of the solitary tract and the C1-C2 spinal segments. The psychological state of an individual can modulate cardiac nociception via pathways involving the amygdala. Descending pathways originating from nucleus raphe magnus and the pons also can modulate cardiac nociception. Sensory input from other visceral organs can mimic cardiac pain due to convergence of this input with cardiac input onto spinothalamic tract neurons. Reduction of converging nociceptive input from the gallbladder and gastrointestinal tract can diminish cardiac pain. Much work remains to be performed to discern the interactions among complex neural pathways that ultimately produce or do not produce the sensations associated with cardiac pain.

  17. Stem cells for cardiac repair: an introduction

    Institute of Scientific and Technical Information of China (English)

    Bastiaan C du Pr(e); Pieter A Doevendans; Linda W van Laake

    2013-01-01

    Cardiovascular disease is a major cause of morbidity and mortality throughout the world. Most cardiovascular diseases, such as ischemic heart disease and cardiomyopathy, are associated with loss of functional cardiomyocytes. Unfortunately, the heart has a limited regenerative capacity and is not able to replace these cardiomyocytes once lost. In recent years, stem cells have been put forward as a potential source for cardiac regeneration. Pre-clinical studies that use stem cell-derived cardiac cells show promising results. The mechanisms, though, are not well understood, results have been variable, sometimes transient in the long term, and often without a mechanistic explanation. There are still several major hurdles to be taken. Stem cell-derived cardiac cells should resemble original cardiac cell types and be able to integrate in the damaged heart. Integration requires administration of stem cell-derived cardiac cells at the right time using the right mode of delivery. Once delivered, transplanted cells need vascularization, electrophysiological coupling with the injured heart, and prevention of immunological rejection. Finally, stem cell therapy needs to be safe, reproducible, and affordable. In this review, we will give an introduction to the principles of stem cell based cardiac repair.

  18. Comparative study of myocytes from normal and mdx mice iPS cells.

    Science.gov (United States)

    Chen, Fei; Cao, Jiqing; Liu, Qiang; Qin, Jie; Kong, Jie; Wang, Yanyun; Li, Yaqin; Geng, Jia; Li, Qiuling; Yang, Liqing; Xiang, Andy Peng; Zhang, Cheng

    2012-02-01

    Recently, induced pluripotent stem cells (iPS cells) have been derived from various techniques and show great potential for therapy of human diseases. Furthermore, the iPS technique can be used to provide cell models to explore pathological mechanisms of many human diseases in vitro, such as Duchenne muscular dystrophy (DMD), which is a severe recessive X-linked form of muscular dystrophy without effective treatment. In this study, we try to determine whether there are different characteristics of myocytes from mdx iPS cells and C57BL/10 iPS cells. Our results showed that both of mdx and C57BL/10 cells could be induced into iPS cells in vitro, whereas colony-forming ability of mdx iPS cells was much weaker than that of C57BL/10 iPS cells. Meanwhile, mdx iPS cells could be induced to differentiate into myocytes, whereas their differentiation efficiency was much lower than that of C57BL/10 iPS cells. And, the number of apoptotic cells in differentiated myocytes from mdx iPS cells was significantly higher than that from C57BL/10 iPS cells. More importantly, treatment of a pan-caspase inhibitor (Z-VAD) produced a significant decrease in apoptotic cells. This study might add some insight to the biology study of dystrophin gene.

  19. Evidence for selective regulation of the phosphorylation of myocyte proteins by isoproterenol and prostaglandin E1.

    Science.gov (United States)

    Hayes, J S; Bowling, N; King, K L; Boder, G B

    1982-01-12

    Both isoproterenol and prostaglandin E1 increased the activation state of cyclic AMP-dependent protein kinase in cultured myocytes; however, only isoproterenol enhanced phosphorylase activity and contractile state. Following the incubation of intact myocytes with 32PO3-(4), 32 phosphoproteins were resolved from total cellular proteins by electrophoresis in sodium dodecyl sulfate polyacrylamide gels followed by autoradiography. Isoproterenol stimulated 32PO3-(4) incorporation into 16 proteins, including 2 phosphoproteins not observed under control conditions. By contrast, prostaglandin E1 neither caused a measurable change in the protein phosphorylation pattern nor interfered with isoproterenol's capacity to do so. Isoproterenol stimulated myocyte protein phosphorylation in either the presence or absence of extracellular Ca2+. The results suggest that the regulation of protein phosphorylation following adenylate cyclase stimulation is: (1) an agonist-specific process and not due solely to a random accumulation of intracellular cycle AMP and activation of protein kinase; (2) the Ca2+ mobilization component of beta-receptor activation does not account for the paradoxical effects of isoproterenol and prostaglandin E1; (3) activation of cyclic AMP-dependent protein kinase does not always result in an enhancement of protein phosphorylation.

  20. Effect of naloxone on L-type calcium current in isolated rat ventricular myocytes%纳洛酮对大鼠心室肌细胞L型钙电流的影响

    Institute of Scientific and Technical Information of China (English)

    王群超; 闻庆平

    2011-01-01

    Objective To evaluate the effect of naloxone on L-type calcium current (ICa-L) in isolated rat ventricular myocytes.Methods Adult SD rats of both sexes aged 8 weeks weighing 200-250 g were used in this study.Single cardiac ventricular myocytes were enzymatically isolated from SD rats.ICa-L was measured in ventricular myocytes and recorded using whole cell patch-clamp technique.Different concentrations (20 and 100 μg/ml) of naloxone were added to the cardiomyocytes.The effect of naloxone on ICa-L was evaluated.Results The peak current of ICa-L Was inhibited by naloxone in a concentration-dependent manner.Naloxone had no significant effect on steady-state activation curve.Conclusion Naloxone inhibits the L-type calcium channel of ventricular myocytes and exerts negative effect on ventricular muscle function.%目的 评价纳洛酮对大鼠心室肌细胞L型钙电流(ICa-L)的影响.方法 采用急性酶解法分离SD大鼠单个心室肌细胞,以全细胞膜片钳技术测定ICa-L.纳洛酮采用累积给药法,记录不同浓度(20和100μg/ml)纳洛酮作用下心室肌细胞ICa-L和给药前、后半激活电压.结果 20和100 μg/ml的纳洛酮分别使L型钙通道峰电流强度从给药前(341±30) pA降至(270±23) pA和(173±21) pA,与20μg/ml纳洛酮相比,100μg/ml纳洛酮给药后L型钙通道峰电流强度降低(P<0.05).20和100μg/ml纳洛酮给药前、后半激活电压比较差异无统计学意义(P>0.05).结论 纳洛酮可抑制大鼠心室肌细胞L型钙通道,具有心室肌负性肌力作用.

  1. Effects of rHu-EPO on Myocyte Apoptosis and Cardiac Function Follow-ing Acute Myocardial Infarction in Rats

    Institute of Scientific and Technical Information of China (English)

    YE Liang; DU Xinling; XIA Jiahong; JIANG Ping

    2005-01-01

    The mechanisms of rHu-EPO attenuating the apoptosis after myocardial infarction in rats were studied. Thirty-two rats were divided into three groups: sham operation group (Sham), acute myocardial infarction group (MI) and rHu-EPO-treated group (MI+ EPO). Acute myocardial infarction model was made by ligating the anterior descending coronary artery. rHu-EPO was administered i. p. in MI+EPO group at the dose of 5 000 IU/kg body weight immediately after the ligation. Each rat in MI+EPO group received the same dose of rHu-EPO daily the next 6 days. On the 14th day all rats underwent hemodynamic measurements and then killed. The samples were examined with HE stain, immunohistochemistry technique (bcl-2, bax) and TUNEL dyeing. The results showed that hemodynamic function in MI+ EPO group was much better than in MI group.The number of the cells positive for bax and TUNEL in MI+EPO group was less than that in MI group. The number of the cells positive for bcl-2 in MI+EPO group was more than that in MI group. These findings suggested that rHu-EPO could treat myocardial infarction by preventing apoptosis and attenuating post-infarction deterioration in hemodynamic function.

  2. S100A4 is upregulated in injured myocardium and promotes growth and survival of cardiac myocytes

    DEFF Research Database (Denmark)

    Schneider, Mikael; Kostin, Sawa; Strøm, Claes C

    2007-01-01

    RNA expression was increased in hypertrophic rat hearts and that it has pro-cardiomyogenic effects in embryonic stem cell-derived embryoid bodies. We therefore hypothesized that S100A4 could play a supportive role in the injured heart. METHODS AND RESULTS: Here we verify by quantitative real-time PCR...

  3. Immune modulation of cardiac repair and regeneration: the art of mending broken hearts

    Directory of Open Access Journals (Sweden)

    Ivana Zlatanova

    2016-10-01

    Full Text Available The accumulation of immune cells is amongst the earliest responses that manifest in the cardiac tissue after injury. Both innate and adaptive immunity coordinate distinct and mutually non-exclusive events governing cardiac repair including elimination of the cellular debris, compensatory growth of the remaining cardiac tissue, activation of resident or circulating precursor cells, quantitative and qualitative modifications of the vascular network and formation of a fibrotic scar. The present review summarizes the mounting evidence suggesting that the inflammatory response also guides the regenerative process following cardiac damage. In particular, recent literature has reinforced the central role of monocytes/macrophages in poising the refreshment of cardiomyocytes in myocardial infarction- or apical resection-induced cardiac insult. Macrophages dictate cardiac myocyte renewal through stimulation of pre-existing cardiomyocyte proliferation and/or neovascularization. Nevertheless, substantial efforts are required to identify the nature of these macrophage-derived factors as well as the molecular mechanisms engendered by the distinct subsets of macrophages pertaining in the cardiac tissue. Among the growing inflammatory intermediaries that have been recognized as essential player in heart regeneration, we will focus on the role of interleukin-6 and interleukin-13. Finally, it is likely that within the mayhem of the injured cardiac tissue, additional types of inflammatory cells, such as neutrophils, will enter the dance to ignite and refresh the broken heart. However, the protective and detrimental inflammatory pathways have been mainly deciphered in animal models. Future research should be focused on understanding the cellular effectors and molecular signals regulating inflammation in human heart to pave the way for the development of factual therapies targeting the inflammatory compartment in cardiac diseases.

  4. Characterization of Mg2+-regulated TRPM7-like current in human atrial myocytes

    Directory of Open Access Journals (Sweden)

    Macianskiene Regina

    2012-08-01

    Full Text Available Abstract Background TRPM7 (Transient Receptor Potential of the Melastatin subfamily proteins are highly expressed in the heart, however, electrophysiological studies, demonstrating and characterizing these channels in human cardiomyocytes, are missing. Methods We have used the patch clamp technique to characterize the biophysical properties of TRPM7 channel in human myocytes isolated from right atria small chunks obtained from 116 patients in sinus rhythm during coronary artery and valvular surgery. Under whole-cell voltage-clamp, with Ca2+ and K+ channels blocked, currents were generated by symmetrical voltage ramp commands to potentials between -120 and +80 mV, from a holding potential of -80 mV. Results We demonstrate that activated native current has dual control by intracellular Mg2+ (free-Mg2+ or ATP-bound form, and shows up- or down-regulation by its low or high levels, respectively, displaying outward rectification in physiological extracellular medium. High extracellular Mg2+ and Ca2+ block the outward current, while Gd3+, SpM4+, 2-APB, and carvacrol inhibit both (inward and outward currents. Besides, divalents also permeate the channel, and the efficacy sequence, at 20 mM, was Mg2+>Ni2+>Ca2+>Ba2+>Cd2+ for decreasing outward and Ni2+>Mg2+>Ba2+≥Ca2+>Cd2+ for increasing inward currents. The defined current bears many characteristics of heterologously expressed or native TRPM7 current, and allowed us to propose that current under study is TRPM7-like. However, the time of beginning and time to peak as well steady state magnitude (range from 1.21 to 11.63 pA/pF, ncells/patients = 136/77 of induced TRPM7-like current in atrial myocytes from different patients showed a large variability, while from the same sample of human atria all these parameters were very homogenous. We present new information that TRPM7-like current in human myocytes is less sensitive to Mg2+. In addition, in some myocytes (from 24 out of 77 patients that current

  5. Effects of Glucose on Transmembrane Ionic Current of Ventricular Myocytes in Guinea Pig

    Institute of Scientific and Technical Information of China (English)

    AIJing; JIAOJun-dong; WANGHe; DUZhi-min; YANGBao-feng

    2004-01-01

    Aim To determine the effects of glucose oi1APD, IK1, IK, ICa-L of ventricular myocytes in guinea pigs. Methods Whole-cell patch-clamp technique was used to record the changed action potential ionic current induced by glucose of single cell in guinea pig ventricular myocytes, to compare the action of 0, 10 and 20 mmol·L-1 glucoses on transmembrane ionic current. Results (1) Compared with 10 mmol·L-1 glucose concentrations, 0 and 20 mmol·L-1 glucose both shortened APD of ventricular myocytes (P<0.05). (2) The inward components of IK1 density were maximal when the glucose concentration was at 10 mmol·L-1. Normalized 1-V relationships showed that both 0 and 20 mmol·L-1 glucose produced a left-shift of I-V curve. The reverse potential changed from-72.4 mV to-64.6 mV. (3) Compared with 10 mmol·L-1, both 0 and 20 mmol·L-1 glucose markedly increased the ICa-L amplitude and density. The ICa-L current density was (-8.0350.82) pA/pF (n=8) at a test potential of 10 mV when the glucose concentration was 10 mmol·L-1. But its current density decreased to (-5.45±0.67) pA/pF and (-6.50±0.56) pA/pF when glucose concentrations were 0 and 20 mmol·L-1, respectively. (4) The current densities of IK were (18.96±2.86) pA/pF, (8.66±1.87) pA/pF, and(15.32:1:3.12) pA/pF, at ±70mV for 0, 10 and 20 mmol·L-1 glucoses, respectively. Conclusion Glucose in different concentrations has different effects on APD, IK1, IK, and ICa-L of single ventricular myocyte in guinea pigs. There are similar actions of 0 and 20 mmol·L-1 glucoses on the transmembrane ionic current of ventricular myocytes in guinea pigs.

  6. Cardiac rehabilitation services in Denmark: still room for expansion

    DEFF Research Database (Denmark)

    Zwisler, Ann-Dorthe O; Traeden, Ulla I; Videbaek, Jørgen;

    2005-01-01

    AIM: European cardiologists agree that cardiac rehabilitation (CR) should be offered as an integrated part of cardiac care, and CR guidelines have been published. The authors aimed to ascertain the potential for expanding CR coverage at hospitals in Denmark. METHOD: A cross-sectional questionnair...

  7. Validation of a new cardiac image fusion software for three-dimensional integration of myocardial perfusion SPECT and stand-alone 64-slice CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Gaemperli, Oliver; Schepis, Tiziano; Namdar, Mehdi; Valenta, Ines [University Hospital Zurich, Nuclear Cardiology, Cardiovascular Center, Zurich (Switzerland); Kalff, Victor [Alfred Hospital, Department of Nuclear Medicine, Melbourne (Australia); Stefani, Laurent [GE Healthcare Bio-Sciences, Buc Cedex (France); Desbiolles, Lotus; Leschka, Sebastian; Husmann, Lars; Alkadhi, Hatem [University Hospital Zurich, Institute of Diagnostic Radiology, Zurich (Switzerland); Kaufmann, Philipp A. [University Hospital Zurich, Nuclear Cardiology, Cardiovascular Center, Zurich (Switzerland); University of Zurich, Zurich Center for Integrative Human Physiology (ZIHP), Zurich (Switzerland)

    2007-07-15

    Combining the functional information of SPECT myocardial perfusion imaging (SPECT-MPI) and the morphological information of coronary CT angiography (CTA) may allow easier evaluation of the spatial relationship between coronary stenoses and perfusion defects. The aim of the present study was the validation of a novel software solution for three-dimensional (3D) image fusion of SPECT-MPI and CTA. SPECT-MPI with adenosine stress/rest {sup 99m}Tc-tetrofosmin was fused with 64-slice CTA in 15 consecutive patients with a single perfusion defect and a single significant coronary artery stenosis ({>=}50% diameter stenosis). 3D fused SPECT/CT images were analysed by two independent observers with regard to superposition of the stenosed vessel onto the myocardial perfusion defect. Interobserver variability was assessed by recording the X, Y, Z coordinates for the origin of the stenosed coronary artery and the centre of the perfusion defect and measuring the distance between the two landmarks. SPECT-MPI revealed a fixed defect in seven patients, a reversible defect in five patients and a mixed defect in three patients and CTA documented a significant stenosis in the respective subtending coronary artery. 3D fused SPECT/CT images showed a match of coronary lesion and perfusion defect in each patient and the fusion process took less than 15 min. Interobserver variability was excellent for landmark detection (r = 1.00 and r = 0.99, p < 0.0001) and very good for the 3D distance between the two landmarks (r = 0.94, p < 0.001). 3D SPECT/CT image fusion is feasible, reproducible and allows correct superposition of SPECT segments onto cardiac CT anatomy. (orig.)

  8. Retinoid X receptor alpha represses GATA-4-mediated transcription via a retinoid-dependent interaction with the cardiac-enriched repressor FOG-2.

    Science.gov (United States)

    Clabby, Martha L; Robison, Trevor A; Quigley, Heather F; Wilson, David B; Kelly, Daniel P

    2003-02-21

    Dietary vitamin A and its derivatives, retinoids, regulate cardiac growth and development. To delineate mechanisms involved in retinoid-mediated control of cardiac gene expression, the regulatory effects of the retinoid X receptor alpha (RXR alpha) on atrial naturietic factor (ANF) gene transcription was investigated. The transcriptional activity of an ANF promoter-reporter in rat neonatal ventricular myocytes was repressed by RXR alpha in the presence of 9-cis-RA and by the constitutively active mutant RXR alpha F318A indicating that liganded RXR confers the regulatory effect. The RXR alpha-mediated repression mapped to the proximal 147 bp of the rat ANF promoter, a region lacking a consensus retinoid response element but containing several known cardiogenic cis elements including a well characterized GATA response element. Glutathione S-transferase "pull-down" assays revealed that RXR alpha interacts directly with GATA-4, in a ligand-independent manner, via the DNA binding domain of RXR alpha and the second zinc finger of GATA-4. Liganded RXR alpha repressed the activity of a heterologous promoter-reporter construct containing GATA-response element recognition sites in cardiac myocytes but not in several other cell types, suggesting that additional cardiac-enriched factors participate in the repression complex. Co-transfection of liganded RXR alpha and the known cardiac-enriched GATA-4 repressor, FOG-2, resulted in additive repression of GATA-4 activity in ventricular myocytes. In addition, RXR alpha was found to bind FOG-2, in a 9-cis-RA-dependent manner. These data reveal a novel mechanism by which retinoids regulate cardiogenic gene expression through direct interaction with GATA-4 and its co-repressor, FOG-2.

  9. Lasting alterations of the sodium current by short-term hyperlipidemia as a mechanism for initiation of cardiac remodeling.

    Science.gov (United States)

    Biet, M; Morin, N; Benrezzak, O; Naimi, F; Bellanger, S; Baillargeon, J P; Chouinard, L; Gallo-Payet, N; Carpentier, A C; Dumaine, R

    2014-01-15

    Clinical and animal studies indicate that increased fatty acid delivery to lean tissues induces cardiac electrical remodeling and alterations of cellular calcium homeostasis. Since this may represent a mechanism initiating cardiac dysfunction during establishment of insulin resistance and diabetes or anaerobic cardiac metabolism (ischemia), we sought to determine if short-term exposure to high plasma concentration of fatty acid in vivo was sufficient to alter the cardiac sodium current (INa) in dog ventricular myocytes. Our results show that delivery of triglycerides and nonesterified fatty acids by infusion of Intralipid + heparin (IH) for 8 h increased the amplitude of INa by 43% and shifted its activation threshold by -5 mV, closer to the resting membrane potential. Steady-state inactivation (availability) of the channels was reduced by IH with no changes in recovery from inactivation. As a consequence, INa "window" current, a strong determinant of intracellular Na+ and Ca2+ concentrations, was significantly increased. The results indicate that increased circulating fatty acids alter INa gating in manners consistent with an increased cardiac excitability and augmentation of intracellular calcium. Moreover, these changes could still be measured after the dogs were left to recover for 12 h after IH perfusion, suggesting lasting changes in INa. Our results indicate that fatty acids rapidly induce cardiac remodeling and suggest that this process may be involved in the development of cardiac dysfunctions associated to insulin resistance and diabetes.

  10. Production and Characterisation of Anti-Cardiac Troponin-I Monoclonal Antibodies

    Directory of Open Access Journals (Sweden)

    Kh. H. Haider

    1994-01-01

    Full Text Available Cardiac troponin-I (cTn-I was isolated from bovine left ventricular tissue and used as immunogen. Sixteen murine hybridoma lines were produced with two of them. I D 12 and 5F4, showing a high specificity for cTn-I; both of these monoclonal antibodies (McAbs were isotyped as IgG I with kappa - light chains. The specificity of the McAbs for cTn-1 was confirmed by ELISA, western blotting and by the ability of the antibodies to block actomyosin ATPase inhibition by cTn-I. The McAbs may be useful for human ill vivo imaging of myocardial infarcts and other pathological conditions related to cardiac myocyte damage.

  11. Cardiac MRI in a Patient with Coincident Left Ventricular Non-Compaction and Hypertrophic Cardiomyopathy

    Directory of Open Access Journals (Sweden)

    Zahra Alizadeh-Sani

    2011-12-01

    Full Text Available Left ventricular non-compaction cardiomyopathy is a rare congenital cardiomyopathy that affects both children and adults. Since the clinical manifestations are not sufficient to establish diagnosis, echocardiography is the diagnostic tool that makes it possible to document ventricular non-compaction and establish prognostic factors. We report a 47-year-old woman with a history of dilated cardiomyopathy with unknown etiology. Echocardiography showed mild left ventricular enlargement with severe systolic dysfunction (EF = 20-25%. According to cardiac magnetic resonance imaging findings non-compaction left ventricle with hypertrophic cardiomyopathy was considered, and right ventricular septal biopsy was recommended. Right ventricular endomyocardial biopsy showed moderate hypertrophy of cardiac myocytes with foci of myocytolysis and moderate interstitial fibrosis. No evidence of infiltrative deposition was seen.

  12. Marketing cardiac CT programs.

    Science.gov (United States)

    Scott, Jason

    2010-01-01

    There are two components of cardiac CT discussed in this article: coronary artery calcium scoring (CACS) and coronary computed tomography angiography (CCTA).The distinctive advantages of each CT examination are outlined. In order to ensure a successful cardiac CT program, it is imperative that imaging facilities market their cardiac CT practices effectively in order to gain a competitive advantage in this valuable market share. If patients receive quality care by competent individuals, they are more likely to recommend the facility's cardiac CT program. Satisfied patients will also be more willing to come back for any further testing.

  13. Preserved cardiac function despite marked impairment of cAMP generation.

    Directory of Open Access Journals (Sweden)

    Mei Hua Gao

    Full Text Available OBJECTIVES: So many clinical trials of positive inotropes have failed, that it is now axiomatic that agents that increase cAMP are deleterious to the failing heart. An alternative strategy is to alter myocardial Ca(2+ handling or myofilament response to Ca(2+ using agents that do not affect cAMP. Although left ventricular (LV function is tightly linked to adenylyl cyclase (AC activity, the beneficial effects of AC may be independent of cAMP and instead stem from effects on Ca(2+ handling. Here we ask whether an AC mutant molecule that reduces LV cAMP production would have favorable effects on LV function through its effects on Ca(2+ handling alone. METHODS AND RESULTS: We generated transgenic mice with cardiac-directed expression of an AC6 mutant (AC6mut. Cardiac myocytes showed impaired cAMP production in response to isoproterenol (74% reduction; p<0.001, but LV size and function were normal. Isolated hearts showed preserved LV function in response to isoproterenol stimulation. AC6mut expression was associated with increased sarcoplasmic reticulum Ca(2+ uptake and the EC50 for SERCA2a activation was reduced. Cardiac myocytes isolated from AC6mut mice showed increased amplitude of Ca(2+ transients in response to isoproterenol (p = 0.0001. AC6mut expression also was associated with increased expression of LV S100A1 (p = 0.03 and reduced expression of phospholamban protein (p = 0.01. CONCLUSION: LV AC mutant expression is associated with normal cardiac function despite impaired cAMP generation. The mechanism appears to be through effects on Ca(2+ handling - effects that occur despite diminished cAMP.

  14. MT1-MMP-dependent remodeling of cardiac extracellular matrix structure and function following myocardial infarction.

    Science.gov (United States)

    Koenig, Gerald C; Rowe, R Grant; Day, Sharlene M; Sabeh, Farideh; Atkinson, Jeffrey J; Cooke, Kenneth R; Weiss, Stephen J

    2012-05-01

    The myocardial extracellular matrix (ECM), an interwoven meshwork of proteins, glycoproteins, proteoglycans, and glycosaminoglycans that is dominated by polymeric fibrils of type I collagen, serves as the mechanical scaffold on which myocytes are arrayed for coordinated and synergistic force transduction. Following ischemic injury, cardiac ECM remodeling is initiated via localized proteolysis, the bulk of which has been assigned to matrix metalloproteinase (MMP) family members. Nevertheless, the key effector(s) of myocardial type I collagenolysis both in vitro and in vivo have remained unidentified. In this study, using cardiac explants from mice deficient in each of the major type I collagenolytic MMPs, including MMP-13, MMP-8, MMP-2, MMP-9, or MT1-MMP, we identify the membrane-anchored MMP, MT1-MMP, as the dominant collagenase that is operative within myocardial tissues in vitro. Extending these observations to an in vivo setting, mice heterozygous for an MT1-MMP-null allele display a distinct survival advantage and retain myocardial function relative to wild-type littermates in an experimental model of myocardial infarction, effects associated with preservation of the myocardial type I collagen network as a consequence of the decreased collagenolytic potential of cardiac fibroblasts. This study identifies MT1-MMP as a key MMP responsible for effecting postinfarction cardiac ECM remodeling and cardiac dysfunction.

  15. Difference of Sodium Currents between Pediatric and Adult Human Atrial Myocytes: Evidence for Developmental Changes of Sodium Channels

    Directory of Open Access Journals (Sweden)

    Benzhi Cai, Xiaoqin Mu, Dongmei Gong, Shulin Jiang, Jianping Li, Qingxin Meng, Yunlong Bai, Yanju Liu, Xinyue Wang, Xueying Tan, Baofeng Yang, Yanjie Lu

    2011-01-01

    Full Text Available Voltage-gated calcium currents and potassium currents were shown to undergo developmental changes in postnatal human and animal cardiomocytes. However, so far, there is no evidence whether sodium currents also presented the developmental changes in postnatal human atrial cells. The aim of this study was to observe age-related changes of sodium currents between pediatric and adult atrial myocytes. Human atrial myocytes were acutely isolated and the whole-cell patch clamp technique was used to record sodium currents isolated from pediatric and adult atrial cardiomocytes. The peak amplitude of sodium currents recorded in adult atrial cells was significantly larger than that in pediatric atrial myocytes. However, there was no significant difference of the activation voltage for peak sodium currents between two kinds of atrial myocytes. The time constants for the activation and inactivation of sodium currents were smaller in adult atria than pediatric atria. The further study revealed that the voltage-dependent inactivation of sodium currents were more slow in adult atrial cardiomyocytes than pediatric atrial cells. A significant difference was also observed in the recovery process of sodium channel from inactivation. In summary, a few significant differences were demonstrated in sodium currents characteristics between pediatric and adult atrial myocytes, which indicates that sodium currents in human atria also undergo developmental changes.

  16. Ubiquitin-Specific Protease 4 Is an Endogenous Negative Regulator of Pathological Cardiac Hypertrophy.

    Science.gov (United States)

    He, Ben; Zhao, Yi-Chao; Gao, Ling-Chen; Ying, Xiao-Ying; Xu, Long-Wei; Su, Yuan-Yuan; Ji, Qing-Qi; Lin, Nan; Pu, Jun

    2016-06-01

    Dysregulation of the ubiquitin proteasome system components ubiquitin ligases and proteasome plays an important role in the pathogenesis of cardiac hypertrophy. However, little is known about the role of another ubiquitin proteasome system component, the deubiquitinating enzymes, in cardiac hypertrophy. Here, we revealed a crucial role of ubiquitin specific protease 4 (USP4), a deubiquitinating enzyme prominently expressed in the heart, in attenuating pathological cardiac hypertrophy and dysfunction. USP4 levels were consistently decreased in human failing hearts and in murine hypertrophied hearts. Adenovirus-mediated gain- and loss-of-function approaches indicated that deficiency of endogenous USP4 promoted myocyte hypertrophy induced by angiotensin II in vitro, whereas restoration of USP4 significantly attenuated the prohypertrophic effect of angiotensin II. To corroborate the role of USP4 in vivo, we generated USP4 global knockout mice and mice with cardiac-specific overexpression of USP4. Consistent with the in vitro study, USP4 depletion exacerbated the hypertrophic phenotype and cardiac dysfunction in mice subjected to pressure overload, whereas USP4 transgenic mice presented ameliorated pathological cardiac hypertrophy compared with their control littermates. Molecular analysis revealed that USP4 deficiency augmented the activation of the transforming growth factor β-activated kinase 1 (TAK1)-(JNK1/2)/P38 signaling in response to hypertrophic stress, and blockage of TAK1 activation abolished the pathological effects of USP4 deficiency in vivo. These findings provide the first evidence for the involvement of USP4 in cardiac hypertrophy, and shed light on the therapeutic potential of targeting USP4 in the treatment of cardiac hypertrophy.

  17. 'Integration'

    DEFF Research Database (Denmark)

    Olwig, Karen Fog

    2011-01-01

    After a long history dominated by out-migration, Denmark, Norway and Sweden have, in the past 50 years, become immigration societies. This article compares how these Scandinavian welfare societies have sought to incorporate immigrants and refugees into their national communities. It suggests that......, while the countries have adopted disparate policies and ideologies, differences in the actual treatment and attitudes towards immigrants and refugees in everyday life are less clear, due to parallel integration programmes based on strong similarities in the welfare systems and in cultural notions...... of equality in the three societies. Finally, it shows that family relations play a central role in immigrants’ and refugees’ establishment of a new life in the receiving societies, even though the welfare society takes on many of the social and economic functions of the family....

  18. Effect of hydrogen peroxide on persistent sodium current in guinea pig ventricular myocytes

    Institute of Scientific and Technical Information of China (English)

    Ji-hua MA; An-tao LUO; Pei-hua ZHANG

    2005-01-01

    Aim: To study the effect of hydrogen peroxide (H2O2) on persistent sodium current (INa.P) in guinea pig ventricular myocytes.Methods: The whole-cell, cell-attached, and inside-out patch-clamp techniques were applied on isolated ventricular myocytes from guinea pig.Results: H2O2 (0.1 mmol/L, 0.5 mmol/L and 1.0mmol/L) increased the amplitude of whole-cell INa.P in a concentration-dependent mmol/L) increased persistent sodium channel activity in cell-attached and insideout patches.The mean open probability was increased from control values of 0.015±0.004 and 0.012±0.003 to 0.106±0.011 and 0.136±0.010, respectively (P<0.01 vs control).They were then decreased to 0.039±0.024 and 0.027±0.006,respectively, after the addition of 1 mmol/L GSH (P<0.01 vs H2O2).The time when open probability began to increase and reached a maximum was shorter in insideout patches than that in cell-attached patches (4.8± 1.0 min vs 11.5±3.9 min, P<0.01;9.6±1.6 min vs 18.7±4.7 min, P<0.01).Conclusion: H2O2 increased the INa.P of guinea pig ventricular myocytes in a concentration-dependent manner, possibly by directly oxidating the cell membrane.

  19. Ca2+ paradox injury mediated through TRPC channels in mouse ventricular myocytes.

    Science.gov (United States)

    Kojima, Akiko; Kitagawa, Hirotoshi; Omatsu-Kanbe, Mariko; Matsuura, Hiroshi; Nosaka, Shuichi

    2010-12-01

    BACKGROUND AND PURPOSE The Ca(2+) paradox is an important phenomenon associated with Ca(2+) overload-mediated cellular injury in myocardium. The present study was undertaken to elucidate molecular and cellular mechanisms for the development of the Ca(2+) paradox. EXPERIMENTAL APPROACH Fluorescence imaging was performed on fluo-3 loaded quiescent mouse ventricular myocytes using confocal laser scanning microscope. KEY RESULTS The Ca(2+) paradox was readily evoked by restoration of the extracellular Ca(2+) following 10-20 min of nominally Ca(2+)-free superfusion. The Ca(2+) paradox was significantly reduced by blockers of transient receptor potential canonical (TRPC) channels (2-aminoethoxydiphenyl borate, Gd(3+), La(3+)) and anti-TRPC1 antibody. The sarcoplasmic reticulum (SR) Ca(2+) content, assessed by caffeine application, gradually declined during Ca(2+)-free superfusion, which was further accelerated by metabolic inhibition. Block of SR Ca(2+) leak by tetracaine prevented Ca(2+) paradox. The Na(+) /Ca(2+) exchange (NCX) blocker KB-R7943 significantly inhibited Ca(2+) paradox when applied throughout superfusion period, but had little effect when added for a period of 3 min before and during Ca(2+) restoration. The SR Ca(2+) content was better preserved during Ca(2+) depletion by KB-R7943. Immunocytochemistry confirmed the expression of TRPC1, in addition to TRPC3 and TRPC4, in mouse ventricular myocytes. CONCLUSIONS AND IMPLICATIONS These results provide evidence that (i) the Ca(2+) paradox is primarily mediated by Ca(2+) entry through TRPC (probably TRPC1) channels that are presumably activated by SR Ca(2+) depletion; and (ii) reverse mode NCX contributes little to the Ca(2+) paradox, whereas inhibition of NCX during Ca(2+) depletion improves SR Ca(2+) loading, and is associated with reduced incidence of Ca(2+) paradox in mouse ventricular myocytes.

  20. The Unfolded Protein Response Regulates Uterine Myocyte Antioxidant Responsiveness During Pregnancy.

    Science.gov (United States)

    Ramnarayanan, Saiprasad; Kyathanahalli, Chandrashekara; Ingles, Judith; Park-York, MieJung; Jeyasuria, Pancharatnam; Condon, Jennifer C

    2016-12-01

    There is considerable evidence that implicates oxidative stress in the pathophysiology of human pregnancy complications. However, the role and the mechanism of maintaining an antioxidant prosurvival uterine environment during normal pregnancy is largely unresolved. Herein we report that the highly active uterine unfolded protein response plays a key role in promoting antioxidant activity in the uterine myocyte across gestation. The unfolded protein response (UPR) senses the accumulation of misfolded proteins in the endoplasmic reticulum (ER) and activates a signaling network that consists of the transmembrane protein kinase eukaryotic translation initiation factor 2 alpha kinase 3/PKR-like-ER kinase (EIF2AK3), which acts to decrease protein translation levels, allowing for a lowered need for protein folding during periods of ER stress. However, independent of its translational regulatory capacity, EIF2AK3-dependent signals elicit the activation of the transcription factor, nuclear factor erythroid 2-like 2 (NFE2L2) in response to oxidative stress. NFE2L2 binds to antioxidant response elements in the promoters of a variety of antioxidant genes that minimize the opportunities for generation of reactive oxygen intermediates. Our analysis demonstrates that in the absence of EIF2AK3, the uterine myocyte experiences increased levels of reactive oxygen species due to decreased NFE2L2 activation. Elevated levels of intracellular reactive oxygen species were observed in the EIF2AK3 null cells, and this was associated with the onset of apoptotic cell death. These findings confirm the prosurvival and antioxidant role of UPR-mediated EIF2AK3 activation in the context of the human uterine myocyte.

  1. Cardiac Procedures and Surgeries

    Science.gov (United States)

    ... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Cardiac Procedures and Surgeries Updated:Sep 16,2016 If you've had ... degree of coronary artery disease (CAD) you have. Cardiac Procedures and Surgeries Angioplasty Also known as Percutaneous Coronary Interventions [PCI], ...

  2. [Advances in cardiac pacing].

    Science.gov (United States)

    de Carranza, María-José Sancho-Tello; Fidalgo-Andrés, María Luisa; Ferrer, José Martínez; Mateas, Francisco Ruiz

    2012-01-01

    This article contains a review of the current status of remote monitoring and follow-up involving cardiac pacing devices and of the latest developments in cardiac resynchronization therapy. In addition, the most important articles published in the last year are discussed.

  3. Mathematical cardiac electrophysiology

    CERN Document Server

    Colli Franzone, Piero; Scacchi, Simone

    2014-01-01

    This book covers the main mathematical and numerical models in computational electrocardiology, ranging from microscopic membrane models of cardiac ionic channels to macroscopic bidomain, monodomain, eikonal models and cardiac source representations. These advanced multiscale and nonlinear models describe the cardiac bioelectrical activity from the cell level to the body surface and are employed in both the direct and inverse problems of electrocardiology. The book also covers advanced numerical techniques needed to efficiently carry out large-scale cardiac simulations, including time and space discretizations, decoupling and operator splitting techniques, parallel finite element solvers. These techniques are employed in 3D cardiac simulations illustrating the excitation mechanisms, the anisotropic effects on excitation and repolarization wavefronts, the morphology of electrograms in normal and pathological tissue and some reentry phenomena. The overall aim of the book is to present rigorously the mathematica...

  4. Atrophic cardiac remodeling induced by taurine deficiency in Wistar rats.

    Directory of Open Access Journals (Sweden)

    Mariele Castilho Pansani

    Full Text Available INTRODUCTION: Micronutrient deficiency is observed in heart failure patients. Taurine, for example, represents 50% of total free amino acids in the heart, and in vivo studies have linked taurine deficiency with cardiomyopathy. METHODS: Thirty-four male Wistar rats (body weight = 100 g were weighed and randomly assigned to one of two groups: Control (C or taurine-deficient (T (-. Beta-alanine at a concentration of 3% was added to the animals' water to induce taurine deficiency in the T (- group. On day 30, the rats were individually submitted to echocardiography; morphometrical and histopathological evaluation and metalloproteinase activity, oxidative stress and inflammation evaluation were performed. Tissue samples were collected to determine the taurine concentration in the heart. RESULTS: Taurine deficiency led to decreases in: ventricular wall thickness, left ventricle dry weight, myocyte sectional area, left ventricle posterior wall thickness and ventricular geometry. With regard to heart function, the velocity of the A wave, the ratio between the E and A wave, the ejection fraction, fractional shortening and cardiac output values were decreased in T (- rats, suggesting abnormal diastolic and systolic function. Increased fibrosis, inflammation and increased activation of metalloproteinases were not observed. Oxidative stress was increased in deficient animals. CONCLUSIONS: These data suggest that taurine deficiency promotes structural and functional cardiac alterations with unique characteristics.

  5. Increase in action potential duration and inhibition of the delayed rectifier outward current IK by berberine in cat ventricular myocytes.

    OpenAIRE

    Sánchez-Chapula, J.

    1996-01-01

    1. In the present work, the effects of the antiarrhythmic drug, berberine, on action potential and ionic currents of cat ventricular myocytes were studied. 2. Berberine prolonged action potential duration in cat ventricular myocytes without altering other variables of the action potential. 3. The drug at concentrations of 0.3-30 microM blocked only the delayed rectifier (IK) current with an IC50 = 4.1 microM. Berberine produced a tonic block and a phasic block that was increased with the dura...

  6. Caveolin-3 expression and caveolae are required for isoflurane-induced cardiac protection from hypoxia and ischemia/reperfusion injury.

    Science.gov (United States)

    Horikawa, Yousuke T; Patel, Hemal H; Tsutsumi, Yasuo M; Jennings, Michelle M; Kidd, Michael W; Hagiwara, Yasuko; Ishikawa, Yoshihiro; Insel, Paul A; Roth, David M

    2008-01-01

    Volatile anesthetics protect the heart from ischemia/reperfusion injury but the mechanisms for this protection are poorly understood. Caveolae, sarcolemmal invaginations, and caveolins, scaffolding proteins in caveolae, localize molecules involved in cardiac protection. We tested the hypothesis that caveolae and caveolins are essential for volatile anesthetic-induced cardiac protection using cardiac myocytes (CMs) from adult rats and in vivo studies in caveolin-3 knockout mice (Cav-3(-/-)). We incubated CM with methyl-beta-cyclodextrin (MbetaCD) or colchicine to disrupt caveolae formation, and then exposed the myocytes to the volatile anesthetic isoflurane (30 min, 1.4%), followed by simulated ischemia/reperfusion (SI/R). Isoflurane protected CM from SI/R [23.2+/-1.6% vs. 71.0+/-5.8% cell death (assessed by trypan blue exclusion), Pprotection was abolished by MbetaCD or colchicine (84.9+/-5.5% and 64.5+/-6.1% cell death, Pprotection in vivo was assessed by measurement of infarct size relative to the area at risk and cardiac troponin levels. Isoflurane-induced a reduction in infarct size and cardiac troponin relative to control (infarct size: 26.5%+/-2.6% vs. 45.3%+/-5.4%, Pprotection was abolished in Cav-3(-/-) mice (infarct size: 53.4%+/-6.1% vs. 53.2%+/-3.5%, Pprotection is thus dependent on the presence of caveolae and the expression of caveolin-3. We conclude that caveolae and caveolin-3 are critical for volatile anesthetic-induced protection of the heart from ischemia/reperfusion injury.

  7. Cardiac tumors: echo assessment.

    Science.gov (United States)

    Mankad, Rekha; Herrmann, Joerg

    2016-12-01

    Cardiac tumors are exceedingly rare (0.001-0.03% in most autopsy series). They can be present anywhere within the heart and can be attached to any surface or be embedded in the myocardium or pericardial space. Signs and symptoms are nonspecific and highly variable related to the localization, size and composition of the cardiac mass. Echocardiography, typically performed for another indication, may be the first imaging modality alerting the clinician to the presence of a cardiac mass. Although echocardiography cannot give the histopathology, certain imaging features and adjunctive tools such as contrast imaging may aid in the differential diagnosis as do the adjunctive clinical data and the following principles: (1) thrombus or vegetations are the most likely etiology, (2) cardiac tumors are mostly secondary and (3) primary cardiac tumors are mostly benign. Although the finding of a cardiac mass on echocardiography may generate confusion, a stepwise approach may serve well practically. Herein, we will review such an approach and the role of echocardiography in the assessment of cardiac masses.

  8. Dynamics of Ca2+-dependent Cl- channel modulation by niflumic acid in rabbit coronary arterial myocytes.

    Science.gov (United States)

    Ledoux, Jonathan; Greenwood, Iain A; Leblanc, Normand

    2005-01-01

    Calcium-activated chloride channels (Cl(Ca)) are crucial regulators of vascular tone by promoting a depolarizing influence on the resting membrane potential of vascular smooth muscle cells. Niflumic acid (NFA), a potent blocker of Cl(Ca) in vascular myocytes, was shown recently to cause inhibition and paradoxical stimulation of sustained calcium-activated chloride currents [I(Cl(Ca))] in rabbit pulmonary artery myocytes. The aims of the present study were to investigate whether NFA produced a similar dual effect in coronary artery smooth muscle cells and to determine the concentration-dependence and dynamics of such a phenomenon. Sustained I(Cl(Ca)) evoked by intracellular Ca(2+) clamped at 500 nM were dose-dependently inhibited by NFA (IC(50) = 159 microM) and transiently augmented in a concentration-independent manner (10 microM to 1 mM) approximately 2-fold after NFA removal. However, the time to peak and duration of NFA-enhanced I(Cl(Ca)) increased in a concentration-dependent fashion. Moreover, the rate of recovery was reduced by membrane depolarization, suggesting the involvement of a voltage-dependent step in the interaction of NFA, leading to stimulation of I(Cl(Ca)). Computer simulations derived from a kinetic model involving low (K(i) = 1.25 mM) and high (K(i) < 30 microM) affinity sites could reproduce the properties of the NFA-modulated I(Cl(Ca)) fairly well.

  9. Effects of NIP-141 on K currents in human atrial myocytes.

    Science.gov (United States)

    Seki, Akiko; Hagiwara, Nobuhisa; Kasanuki, Hiroshi

    2002-01-01

    A novel benzopyran derivative, NIP-141, effectively terminates experimental atrial fibrillation in canine hearts by prolonging atrial refractoriness. However, the effects of this drug on human atrial myocytes are unknown. This experiment evaluated the effects of NIP-141 on K currents in isolated human atrial myocytes using a whole-cell voltage-clamp method. NIP-141 inhibited the transient outward current (I(to)) and the ultra-rapid delayed rectifier K current (I(Kur)), each in a dose-dependent manner, with half-maximal inhibition concentrations of 16.3 microM and 5.3 microM, respectively (n = 5). NIP-141 inhibited both K currents in a voltage- and use-independent fashion, and it preferentially blocked them in the open state and dissociated rapidly from the channel. Because both K currents contribute significantly to the repolarization of the atrial action potential, these findings suggest that NIP-141 may terminate atrial fibrillation by prolonging action potential duration.

  10. Laminar structure of the heart: ventricular myocyte arrangement and connective tissue architecture in the dog.

    Science.gov (United States)

    LeGrice, I J; Smaill, B H; Chai, L Z; Edgar, S G; Gavin, J B; Hunter, P J

    1995-08-01

    We have studied the three-dimensional arrangement of ventricular muscle cells and the associated extracellular connective tissue matrix in dog hearts. Four hearts were potassium-arrested, excised, and perfusion-fixed at zero transmural pressure. Full-thickness segments were cut from the right and left ventricular walls at a series of precisely located sites. Morphology was visualized macroscopically and with scanning electron microscopy in 1) transmural planes of section and 2) planes tangential to the epicardial surface. The appearance of all specimens was consistent with an ordered laminar arrangement of myocytes with extensive cleavage planes between muscle layers. These planes ran radially from endocardium toward epicardium in transmural section and coincided with the local muscle fiber orientation in tangential section. Stereological techniques were used to quantify aspects of this organization. There was no consistent variation in the cellular organization of muscle layers (48.4 +/- 20.4 microns thick and 4 +/- 2 myocytes across) transmurally or in different ventricular regions (23 sites in 6 segments), but there was significant transmural variation in the coupling between adjacent layers. The number of branches between layers decreased twofold from subepicardium to midwall, whereas the length distribution of perimysial collagen fibers connecting muscle layers was greatest in the midwall. We conclude that ventricular myocardium is not a uniformly branching continuum but a laminar hierarchy in which it is possible to identify three axes of material symmetry at any point.

  11. Life and death of a cardiac calcium spark.

    Science.gov (United States)

    Stern, Michael D; Ríos, Eduardo; Maltsev, Victor A

    2013-09-01

    Calcium sparks in cardiac myocytes are brief, localized calcium releases from the sarcoplasmic reticulum (SR) believed to be caused by locally regenerative calcium-induced calcium release (CICR) via couplons, clusters of ryanodine receptors (RyRs). How such regeneration is terminated is uncertain. We performed numerical simulations of an idealized stochastic model of spark production, assuming a RyR gating scheme with only two states (open and closed). Local depletion of calcium in the SR was inevitable during a spark, and this could terminate sparks by interrupting CICR, with or without assumed modulation of RyR gating by SR lumenal calcium. Spark termination by local SR depletion was not robust: under some conditions, sparks could be greatly and variably prolonged, terminating by stochastic attrition-a phenomenon we dub "spark metastability." Spark fluorescence rise time was not a good surrogate for the duration of calcium release. Using a highly simplified, deterministic model of the dynamics of a couplon, we show that spark metastability depends on the kinetic relationship of RyR gating and junctional SR refilling rates. The conditions for spark metastability resemble those produced by known mutations of RyR2 and CASQ2 that cause life-threatening triggered arrhythmias, and spark metastability may be mitigated by altering the kinetics of the RyR in a manner similar to the effects of drugs known to prevent those arrhythmias. The model was unable to explain the distributions of spark amplitudes and rise times seen in chemically skinned cat atrial myocytes, suggesting that such sparks may be more complex events involving heterogeneity of couplons or local propagation among sub-clusters of RyRs.

  12. A Wireless Pressure Sensor Integrated with a Biodegradable Polymer Stent for Biomedical Applications.

    Science.gov (United States)

    Park, Jongsung; Kim, Ji-Kwan; Patil, Swati J; Park, Jun-Kyu; Park, SuA; Lee, Dong-Weon

    2016-06-02

    This paper describes the fabrication and characterization of a wireless pressure sensor for smart stent applications. The micromachined pressure sensor has an area of 3.13 × 3.16 mm² and is fabricated with a photosensitive SU-8 polymer. The wireless pressure sensor comprises a resonant circuit and can be used without the use of an internal power source. The capacitance variations caused by changes in the intravascular pressure shift the resonance frequency of the sensor. This change can be detected using an external antenna, thus enabling the measurement of the pressure changes inside a tube with a simple external circuit. The wireless pressure sensor is capable of measuring pressure from 0 mmHg to 230 mmHg, with a sensitivity of 0.043 MHz/mmHg. The biocompatibility of the pressure sensor was evaluated using cardiac cells isolated from neonatal rat ventricular myocytes. After inserting a metal stent integrated with the pressure sensor into a cardiovascular vessel of an animal, medical systems such as X-ray were employed to consistently monitor the condition of the blood vessel. No abnormality was found in the animal blood vessel for approximately one month. Furthermore, a biodegradable polymer (polycaprolactone) stent was fabricated with a 3D printer. The polymer stent exhibits better sensitivity degradation of the pressure sensor compared to the metal stent.

  13. A Wireless Pressure Sensor Integrated with a Biodegradable Polymer Stent for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Jongsung Park

    2016-06-01

    Full Text Available This paper describes the fabrication and characterization of a wireless pressure sensor for smart stent applications. The micromachined pressure sensor has an area of 3.13 × 3.16 mm2 and is fabricated with a photosensitive SU-8 polymer. The wireless pressure sensor comprises a resonant circuit and can be used without the use of an internal power source. The capacitance variations caused by changes in the intravascular pressure shift the resonance frequency of the sensor. This change can be detected using an external antenna, thus enabling the measurement of the pressure changes inside a tube with a simple external circuit. The wireless pressure sensor is capable of measuring pressure from 0 mmHg to 230 mmHg, with a sensitivity of 0.043 MHz/mmHg. The biocompatibility of the pressure sensor was evaluated using cardiac cells isolated from neonatal rat ventricular myocytes. After inserting a metal stent integrated with the pressure sensor into a cardiovascular vessel of an animal, medical systems such as X-ray were employed to consistently monitor the condition of the blood vessel. No abnormality was found in the animal blood vessel for approximately one month. Furthermore, a biodegradable polymer (polycaprolactone stent was fabricated with a 3D printer. The polymer stent exhibits better sensitivity degradation of the pressure sensor compared to the metal stent.

  14. Pioglitazone attenuates cardiac fibrosis and hypertrophy in a rat model of diabetic nephropathy.

    Science.gov (United States)

    Elrashidy, Rania A; Asker, Mervat E; Mohamed, Hoda E

    2012-09-01

    Pioglitazone has been demonstrated to have beneficial effects on cardiovascular outcomes. However, little is known about its effect on cardiac remodeling associated with diabetic nephropathy. Therefore, this study was designed to study the effects of pioglitazone on cardiac fibrosis and hypertrophy in a rat model of diabetic nephropathy. For this purpose, male Wistar albino rats were randomly assigned into 4 groups (n = 10 per group): normal (N) group, diabetic (D) group, diabetic nephropathic (DN) group received an equal amount of vehicle (0.5% carboxy methyl cellulose), and diabetic nephropathic group treated by oral administration of pioglitazone (10 mg/kg per d) for 4 weeks. Diabetic nephropathy was induced by subtotal nephrectomy plus streptozotocin (STZ) injection. The results revealed that DN rats showed excessive deposition of collagen fibers in their cardiac tissue, along with a marked myocyte hypertrophy. This was associated with a dramatic upregulation of cardiac transforming growth factor-β1 (TGF-β1) gene. Furthermore, the gene expression of matrix metalloproteinase 2 (MMP-2) decreased, while the gene expression of tissue inhibitor of metalloproteinase 2 (TIMP-2) increased in the hearts of DN rats. In addition, enhanced lipid peroxidation and myocardial injury, evidenced by a significant increase in their serum creatine kinase-MB level were observed in DN rats. All these abnormalities were ameliorated by pioglitazone administration. Our findings suggest that upregulation of cardiac TGF-β1 gene along with the imbalance between MMP-2 and TIMP-2 expressions is critically involved in cardiac fibrosis associated with diabetic nephropathy. Pioglitazone can ameliorate cardiac remodeling by suppressing the gene expression of TGF-β1 and regulating the MMP-2/TIMP-2 system.

  15. A Novel Human Tissue-Engineered 3-D Functional Vascularized Cardiac Muscle Construct

    Science.gov (United States)

    Valarmathi, Mani T.; Fuseler, John W.; Davis, Jeffrey M.; Price, Robert L.

    2017-01-01

    Organ tissue engineering, including cardiovascular tissues, has been an area of intense investigation. The major challenge to these approaches has been the inability to vascularize and perfuse the in vitro engineered tissue constructs. Attempts to provide oxygen and nutrients to the cells contained in the biomaterial constructs have had varying degrees of success. The aim of this current study is to develop a three-dimensional (3-D) model of vascularized cardiac tissue to examine the concurrent temporal and spatial regulation of cardiomyogenesis in the context of postnatal de novo vasculogenesis during stem cell cardiac regeneration. In order to achieve the above aim, we have developed an in vitro 3-D functional vascularized cardiac muscle construct using human induced pluripotent stem cell-derived embryonic cardiac myocytes (hiPSC-ECMs) and human mesenchymal stem cells (hMSCs). First, to generate the prevascularized scaffold, human cardiac microvascular endothelial cells (hCMVECs) and hMSCs were co-cultured onto a 3-D collagen cell carrier (CCC) for 7 days under vasculogenic culture conditions. In this milieu, hCMVECs/hMSCs underwent maturation, differentiation, and morphogenesis characteristic of microvessels, and formed extensive plexuses of vascular networks. Next, the hiPSC-ECMs and hMSCs were co-cultured onto this generated prevascularized CCCs for further 7 or 14 days in myogenic culture conditions. Finally, the vascular and cardiac phenotypic inductions were analyzed at the morphological, immunological, biochemical, molecular, and functional levels. Expression and functional analyses of the differentiated cells revealed neo-angiogenesis and neo-cardiomyogenesis. Thus, our unique 3-D co-culture system provided us the apt in vitro functional vascularized 3-D cardiac patch that can be utilized for cellular cardiomyoplasty. PMID:28194397

  16. Biomimetic material strategies for cardiac tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakaran, Molamma P., E-mail: nnimpp@nus.edu.sg [Health Care and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Venugopal, J. [Health Care and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Kai, Dan [NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore (Singapore); Ramakrishna, Seeram [Health Care and Energy Materials Laboratory, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore)

    2011-04-08

    Cardiovascular disease precedes many serious complications including myocardial infarction (MI) and it remains a major problem for the global community. Adult mammalian heart has limited ability to regenerate and compensate for the loss of cardiomyocytes. Restoration of cardiac function by replacement of diseased myocardium with functional cardiomyocytes is an intriguing strategy because it offers a potential cure for MI. Biomaterials are fabricated in nanometer scale dimensions by combining the chemical, biological, mechanical and electrical aspects of material for potential tissue engineering (TE) applications. Synthetic polymers offer advantageous in their ability to tailor the mechanical properties, and natural polymers offer cell recognition sites necessary for cell, adhesion and proliferation. Cardiac tissue engineering (TE) aim for the development of a bioengineered construct that can provide physical support to the damaged cardiac tissue by replacing certain functions of the damaged extracellular matrix and prevent adverse cardiac remodeling and dysfunction after MI. Electrospun nanofibers are applied as heart muscle patches, while hydrogels serve as a platform for controlled delivery of growth factors, prevent mechanical complications and assist in cell recruitment. This article reviews the applications of different natural and synthetic polymeric materials utilized as cardiac patches, injectables or 3D constructs for cardiac TE. Smart organization of nanoscale assemblies with synergistic approaches of utilizing nanofibers and hydrogels could further advance the field of cardiac tissue engineering. Rapid innovations in biomedical engineering and cell biology will bring about new insights in the development of optimal scaffolds and methods to create tissue constructs with relevant contractile properties and electrical integration to replace or substitute the diseased myocardium.

  17. Cardiac Electromechanical Models: From Cell to Organ

    Directory of Open Access Journals (Sweden)

    Natalia A Trayanova

    2011-08-01

    Full Text Available The heart is a multiphysics and multiscale system that has driven the development of the most sophisticated mathematical models at the frontiers of computation physiology and medicine. This review focuses on electromechanical (EM models of the heart from the molecular level of myofilaments to anatomical models of the organ. Because of the coupling in terms of function and emergent behaviors at each level of biological hierarchy, separation of behaviors at a given scale is difficult. Here, a separation is drawn at the cell level so that the first half addresses subcellular/single cell models and the second half addresses organ models. At the subcelluar level, myofilament models represent actin-myosin interaction and Ca-based activation. Myofilament models and their refinements represent an overview of the development in the field. The discussion of specific models emphasizes the roles of cooperative mechanisms and sarcomere length dependence of contraction force, considered the cellular basis of the Frank-Starling law. A model of electrophysiology and Ca handling can be coupled to a myofilament model to produce an EM cell model, and representative examples are summarized to provide an overview of the progression of field. The second half of the review covers organ-level models that require solution of the electrical component as a reaction-diffusion system and the mechanical component, in which active tension generated by the myocytes produces deformation of the organ as described by the equations of continuum mechanics. As outlined in the review, different organ-level models have chosen to use different ionic and myofilament models depending on the specific application; this choice has been largely dictated by compromises between model complexity and computational tractability. The review also addresses application areas of EM models such as cardiac resynchronization therapy and the role of mechano-electric coupling in arrhythmias and

  18. Molecular Basis of Cardiac Myxomas

    Directory of Open Access Journals (Sweden)

    Pooja Singhal

    2014-01-01

    Full Text Available Cardiac tumors are rare, and of these, primary cardiac tumors are even rarer. Metastatic cardiac tumors are about 100 times more common than the primary tumors. About 90% of primary cardiac tumors are benign, and of these the most common are cardiac myxomas. Approximately 12% of primary cardiac tumors are completely asymptomatic while others present with one or more signs and symptoms of the classical triad of hemodynamic changes due to intracardiac obstruction, embolism and nonspecific constitutional symptoms. Echocardiography is highly sensitive and specific in detecting cardiac tumors. Other helpful investigations are chest X-rays, magnetic resonance imaging and computerized tomography scan. Surgical excision is the treatment of choice for primary cardiac tumors and is usually associated with a good prognosis. This review article will focus on the general features of benign cardiac tumors with an emphasis on cardiac myxomas and their molecular basis.

  19. Biomarkers for cardiac cachexia: reality or utopia.

    Science.gov (United States)

    Martins, Telma; Vitorino, Rui; Amado, Francisco; Duarte, José Alberto; Ferreira, Rita

    2014-09-25

    Cardiac cachexia is a serious complication of chronic heart failure, characterized by significant weight loss and body wasting. Chronic heart failure-related muscle wasting results from a chronic imbalance in the activation of anabolic or catabolic pathways, caused by a series of immunological, metabolic, and neurohormonal processes. In spite of the high morbidity and mortality associated to this condition, there is no universally accepted definition or specific biomarkers for cardiac cachexia, which makes its diagnosis and treatment difficult. Several hormonal, inflammatory and oxidative stress molecules have been proposed as serological markers of prognosis in cardiac cachexia but with doubtful success. As individual biomarkers may have limited sensitivity and specificity, multimarker strategies involving mediators of the biological processes modulated by cardiac cachexia will strongly contribute for the diagnosis and management of the disease, as well as for the establishment of new therapeutic targets. An integrated analysis of the biomarkers proposed so far for cardiac cachexia is made in the present review, highlighting the biological processes to which they are related.

  20. CpG-ODN attenuates pathological cardiac hypertrophy and heart failure by activation of PI3Kα-Akt signaling.

    Directory of Open Access Journals (Sweden)

    Liang Yang

    Full Text Available Phosphoinositide-3-kinase α (PI3Kα represents a potential novel drug target for pathological cardiac hypertrophy (PCH and heart failure. Oligodeoxynucleotides containing CpG motifs (CpG-ODN are classic agonists of Toll-like receptor 9 (TLR9, which typically activates PI3K-Akt signaling in immune cells; however, the role of the nucleotide TLR9 agonists in cardiac myocytes is largely unknown. Here we report that CpG-ODN C274 could both attenuate PCH and improve cardiac dysfunction by activating PI3Kα-Akt signaling cascade. In vitro studies indicated that C274 could blunt reactivation of fetal cardiac genes and cell enlargement induced by a hypertrophic agent, isoproterenol. The anti-hypertrophic effect of C274 was suppressed by a pan-PI3K inhibitor, LY294002, or a small interfering RNA targeting PI3Kα. In vivo studies demonstrated that PCH, as marked by increased heart weight (HW and cardiac ANF mRNA, was normalized by pre-administration with C274. In addition, Doppler echocardiography detected cardiac ventricular dilation, and contractile dysfunction in isoproterenol-treated animals, consistent with massive replacement fibrosis, reflecting cardiac cell death. As expected, pre-treatment of mice with C274 could prevent cardiac dysfunction associated with diminished cardiac cell death and fibrosis. In conclusion, CpG-ODNs are novel cardioprotective agents possessing antihypertrophic and anti-cell death activity afforded by engagement of the PI3Kα-Akt signaling. CpG-ODNs may have clinical use curbing the progression of PCH and preventing heart failure.

  1. Cardiac Tumors; Tumeurs cardiaques

    Energy Technology Data Exchange (ETDEWEB)

    Laissy, J.P.; Fernandez, P. [Centre Hospitalier Universitaire Bichat Claude Bernard, Service d' Imagerie, 76 - Rouen (France); Mousseaux, E. [Hopital Europeen Georges Pompidou (HEGP), Service de Radiologie Cardio Vasculaire et Interventionnelle, 75 - Paris (France); Dacher, J.N. [Centre Hospitalier Universitaire Charles Nicolle, 75 - Rouen (France); Crochet, D. [Centre Hospitalier Universitaire, Hopital Laennec, Centre Hemodynamique, Radiologie Thoracique et Vasculaire, 44 - Nantes (France)

    2004-04-01

    Metastases are the most frequent tumors of the heart even though they seldom are recognized. Most primary cardiac tumors are benign. The main role of imaging is to differentiate a cardiac tumor from thrombus and rare pseudo-tumors: tuberculoma, hydatid cyst. Echocardiography is the fist line imaging technique to detect cardiac tumors, but CT and MRl arc useful for further characterization and differential diagnosis. Myxoma of the left atrium is the most frequent benign cardiac tumor. It usually is pedunculated and sometimes calcified. Sarcoma is the most frequent primary malignant tumor and usually presents as a sessile infiltrative tumor. Lymphoma and metastases are usually recognized by the presence of known tumor elsewhere of by characteristic direct contiguous involvement. Diagnosing primary and secondary pericardial tumors often is difficult. Imaging is valuable for diagnosis, characterization, pre-surgical evaluation and follow-up. (author)

  2. Socially differentiated cardiac rehabilitation

    DEFF Research Database (Denmark)

    Meillier, Lucette Kirsten; Nielsen, Kirsten Melgaard; Larsen, Finn Breinholt;

    2012-01-01

    to a standard rehabilitation programme (SRP). If patients were identified as socially vulnerable, they were offered an extended version of the rehabilitation programme (ERP). Excluded patients were offered home visits by a cardiac nurse. Concordance principles were used in the individualised programme elements......%. Patients were equally distributed to the SRP and the ERP. No inequality was found in attendance and adherence among referred patients. Conclusions: It seems possible to overcome unequal referral, attendance, and adherence in cardiac rehabilitation by organisation of systematic screening and social......Aim: The comprehensive cardiac rehabilitation (CR) programme after myocardial infarction (MI) improves quality of life and results in reduced cardiac mortality and recurrence of MI. Hospitals worldwide face problems with low participation rates in rehabilitation programmes. Inequality...

  3. Leonurine (SCM-198) improves cardiac recovery in rat during chronic infarction.

    Science.gov (United States)

    Liu, XinHua; Pan, LiLong; Gong, QiHai; Zhu, YiZhun

    2010-12-15

    Leonurine, an alkaloid typically found in Herba leonuri, is known to have both antioxidant and cardioprotective properties. In the present study, we investigated the cardioprotective mechanism of leonurine the in vivo rat model of chronic myocardial ischemia and in vitro H9c2 cardiac myocyte model of oxidative stress. Myocardial ischemia was induced by ligating the left anterior descending coronary artery. Rats were divided into sham, myocardial ischemia+saline, and myocardial ischemia+leonurine (15 mg/kg/day). Cardiac function was recorded by catheterization. Apoptosis-related factor vascular endothelial growth factor (VEGF), survivin, Bcl-2 and Bax and pro-survival signaling pathways Akt, hypoxia inducible factor (HIF)-1α were measured by Western blotting or RT-PCR. Our results showed leonurine significantly improved myocardial function as evidenced by the decreased left ventricle end-diastolic pressure and the increased +dP/dt. Interestingly, leonurine increased the phosphorylation of Akt, the protein and gene expression of Bcl-2, but it reduced the protein and gene expression of Bax in vivo. Meanwhile leonurine significantly increased Akt phosphorylation in a concentration-dependent manner in H9c2 cardiac myocyte induced by oxidative stress in vitro, which was abolished by a phosphoinositide 3-kinase (PI3K) inhibitor, LY294002. Furthermore, leonurine not only increased the expression of HIF-1α but also the expression of survivin and VEGF. The results of present study demonstrated, for the first time that leonurine has potent anti-apoptotic effects after chronic myocardial ischemia mediated by activating the PI3K/Akt signaling pathway. Angiogenic mechanisms may be partially responsible for such an effect, which needs to be studied further.

  4. Cardiac arrest - cardiopulmonary resuscitation

    Institute of Scientific and Technical Information of China (English)

    Basri Lenjani; Besnik Elshani; Nehat Baftiu; Kelmend Pallaska; Kadir Hyseni; Njazi Gashi; Nexhbedin Karemani; Ilaz Bunjaku; Taxhidin Zaimi; Arianit Jakupi

    2014-01-01

    Objective:To investigate application of cardiopulmonary resuscitation(CPR) measures within the golden minutes inEurope.Methods:The material was taken from theUniversityClinical Center ofKosovo -EmergencyCentre inPristina, during the two(2) year period(2010-2011).The collected date belong to the patients with cardiac arrest have been recorded in the patients' log book protocol at the emergency clinic.Results:During the2010 to2011 in the emergency center of theCUCK inPristina have been treated a total of269 patients with cardiac arrest, of whom159 or59.1% have been treated in2010, and110 patients or40.9% in2011.Of the269 patients treated in the emergency centre,93 or34.6% have exited lethally in the emergency centre, and176 or 65.4% have been transferred to other clinics.In the total number of patients with cardiac arrest, males have dominated with186 cases, or69.1%.The average age of patients included in the survey was56.7 year oldSD±16.0 years.Of the269 patients with cardiac arrest, defibrillation has been applied for93 or34.6% of patients.In the outpatient settings defibrillation has been applied for3 or3.2% of patients.Patients were defibrillated with application of one to four shocks. Of27 cases with who have survived cardiac arrest, none of them have suffered cardiac arrest at home,3 or11.1% of them have suffered cardiac arrest on the street, and24 or88.9% of them have suffered cardiac arrest in the hospital.5 out of27 patients survived have ended with neurological impairment.Cardiac arrest cases were present during all days of the week, but frequently most reported cases have been onMonday with32.0% of cases, and onFriday with24.5% of cases. Conclusions:All survivors from cardiac arrest have received appropriate medical assistance within10 min from attack, which implies that if cardiac arrest occurs near an institution health care(with an opportunity to provide the emergent health care) the rate of survival is higher.

  5. Fatal cardiac tamponade as the first manifestation of acute myeloid leukemia.

    Science.gov (United States)

    Leptidis, John; Aloizos, Stavros; Chlorokostas, Panagiotis; Gourgiotis, Stavros

    2014-10-01

    Acute myeloid leukemia is a hemopoietic myeloid stem cell neoplasm. It is the most common acute leukemia affecting adults,and its incidence increases with age. Acute myeloid leukemia is characterized by the rapid growth of abnormal white blood cells that accumulate in the bone marrow and interfere with the production of normal blood cells. As the leukemic cells keep filling the bone marrow, symptoms of the disease started to appear: fatigue, bleeding, increased frequency of infections, and shortness of breath. Cardiac tamponade or pericardial tamponade is an acute medical condition in which the accumulation of pericardial fluid prevents the function of the heart. Signs and symptoms include Beck triad (hypotension, distended neck veins, and muffled heart sounds), paradoxus pulses, tachycardia, tachypnea, and breathlessness. Pericardial effusion and cardiac tamponade are rare and severe complications of leukemia; they often develop during the radiation therapy, chemotherapy, or infections in the course of leukemia. This study sought to assess the fatal cardiac tamponade as the first manifestation of acute myeloid leukemia (AML). We found no reports in the literature linking these 2 clinical entities. Although the patient had no signs or diagnosis of AML previously, this case was remarkable for the rapidly progressive symptoms and the fatal outcome. The pericardial effusion reaccumulated rapidly after its initial drainage; it is a possible explanation that the leukemic cells interfered with cardiac activity or that they decreased their contractility myocytes secreting a toxic essence.

  6. Imaging of cardiac allograft rejection in dogs using indium-111 monoclonal antimyosin Fab

    Energy Technology Data Exchange (ETDEWEB)

    Addonizio, L.J.; Michler, R.E.; Marboe, C.; Esser, P.E.; Johnson, L.L.; Seldin, D.W.; Gersony, W.M.; Alderson, P.O.; Rose, E.A.; Cannon, P.J.

    1987-03-01

    The acute rejection of cardiac allografts is currently diagnosed by the presence of myocyte necrosis on endomyocardial biopsy. We evaluated the efficacy of noninvasive scintigraphic imaging with indium-111-labeled anticardiac myosin Fab fragments (indium-111 antimyosin) to detect and quantify cardiac allograft rejection. Six dogs that had intrathoracic heterotopic cardiac allograft transplantation were injected with indium-111 antimyosin and planar and single photon emission computed tomographic (SPECT) images were obtained in various stages of acute and subacute rejection. Four dogs had an allograft older than 8 months and had been on long-term immunosuppressive therapy; two dogs had an allograft less than 2 weeks old and were not on immunosuppressive therapy. Count ratios comparing heterotopic with native hearts were calculated from both SPECT images and in vitro scans of excised and sectioned hearts and were compared with the degree of rejection scored by an independent histopathologic review. Indium-111 antimyosin uptake was not visible in planar or SPECT images of native hearts. Faint diffuse uptake was apparent in cardiac allografts during long-term immunosuppression and intense radioactivity was present in hearts with electrocardiographic evidence of rejection. The heterotopic to native heart count ratios in SPECT images correlated significantly with the count ratios in the excised hearts (r = 0.93) and with the histopathologic rejection score (r = 0.97). The distribution of indium-111 antimyosin activity in right and left ventricles corresponded to areas of histopathologic abnormalities.

  7. Cardiac imaging in adults

    Energy Technology Data Exchange (ETDEWEB)

    Jaffe, C.C.

    1987-01-01

    This book approaches adult cardiac disease from the correlative imaging perspective. It includes chest X-rays and angiographs, 2-dimensional echocardiograms with explanatory diagrams for clarity, plus details on digital radiology, nuclear medicine techniques, CT and MRI. It also covers the normal heart, valvular heart disease, myocardial disease, pericardial disease, bacterial endocarditis, aortic aneurysm, cardiac tumors, and congenital heart disease of the adult. It points out those aspects where one imaging technique has significant superiority.

  8. Port Access Cardiac Surgery.

    Science.gov (United States)

    Viganó, Mario; Minzioni, Gaetano; Spreafico, Patrizio; Rinaldi, Mauro; Pasquino, Stefano; Ceriana, Piero; Locatelli, Alessandro

    2000-10-01

    The port-access technique for cardiac surgery was recently developed at Stanford University in California as a less invasive method to perform some cardiac operations. The port-access system has been described in detail elsewhere. It is based on femoral arterial and venous access for cardiopulmonary bypass (CPB) and on the adoption of a specially designed triple-lumen catheter described originally by Peters, and subsequently modified and developed in the definitive configuration called the endoaortic clamp.

  9. Awareness in cardiac anesthesia.

    LENUS (Irish Health Repository)

    Serfontein, Leon

    2010-02-01

    Cardiac surgery represents a sub-group of patients at significantly increased risk of intraoperative awareness. Relatively few recent publications have targeted the topic of awareness in this group. The aim of this review is to identify areas of awareness research that may equally be extrapolated to cardiac anesthesia in the attempt to increase understanding of the nature and significance of this scenario and how to reduce it.

  10. Post cardiac injury syndrome

    DEFF Research Database (Denmark)

    Nielsen, S L; Nielsen, F E

    1991-01-01

    The post-pericardiotomy syndrome is a symptom complex which is similar in many respects to the post-myocardial infarction syndrome and these are summarized under the diagnosis of the Post Cardiac Injury Syndrome (PCIS). This condition, which is observed most frequently after open heart surgery, i...... on the coronary vessels, with cardiac tamponade and chronic pericardial exudate. In the lighter cases, PCIS may be treated with NSAID and, in the more severe cases, with systemic glucocorticoid which has a prompt effect....

  11. Autonomic cardiac innervation

    OpenAIRE

    Hasan, Wohaib

    2013-01-01

    Autonomic cardiac neurons have a common origin in the neural crest but undergo distinct developmental differentiation as they mature toward their adult phenotype. Progenitor cells respond to repulsive cues during migration, followed by differentiation cues from paracrine sources that promote neurochemistry and differentiation. When autonomic axons start to innervate cardiac tissue, neurotrophic factors from vascular tissue are essential for maintenance of neurons before they reach their targe...

  12. Infected cardiac hydatid cyst

    OpenAIRE

    Ceviz, M; Becit, N; Kocak, H.

    2001-01-01

    A 24 year old woman presented with chest pain and palpitation. The presence of a semisolid mass—an echinococcal cyst or tumour—in the left ventricular apex was diagnosed by echocardiography, computed tomography, and magnetic resonance imaging. The infected cyst was seen at surgery. The cyst was removed successfully by using cardiopulmonary bypass with cross clamp.


Keywords: cardiac hydatid cyst; infected cardiac hydatid cyst

  13. Characteristics of the inward-rectifying potassium current in mouse ventricular myocytes and its relation to early after-depolarization

    Institute of Scientific and Technical Information of China (English)

    周盈颖; 郝雪梅; 范劲松; 刘泰(木逢)

    1996-01-01

    The properties of the inward-rectifying potassium current (IK1) were studied in the single myocytes isolated from adult mouse ventricles by the whole-cell patch-damp technique for the first time. Most of the properties of IK1 including channel conductances, activation, inactivation, rectification and external K+ sensitivity in mouse ventricular myocyte were similar to those in other species, but the current-voltage (1-V) curve of mouse ventricular myocyte showed no negative slope, i.e the slope in the range of membrane potential 50 mV positive to the reversal potential (VRev) was virtually flat and remained at a low current level ((59±39) pA). Under the superfusion of Tyrode’s solution with 3mmol/L K+ and 3mmol/L Cs+, IK1 in the above region nearly decreased to zero, and then the early after-depolarization (EAD) occurred. The results suggest that this distinctive characteristic of IK1 in mouse ventricular myocyte may relate to the high susceptibility to EA0 in mouse myocardium. The inhibition of IK1 se

  14. Effect of Tanshinone Ⅱ -A on L-type calcium channel in rat ventricular myocytes%丹参Ⅱ-A对大鼠心肌细胞L-型钙通道的影响 

    Institute of Scientific and Technical Information of China (English)

    黄健; 裴娟慧; 滕思勇; 郝杰; 张银辉; 浦介麟; 惠汝太

    2012-01-01

    目的 研究丹参酮Ⅱ-A对大鼠心肌细胞L型钙通道的影响.方法 采用酶解法制备大鼠心肌细胞,应用全细胞膜片钳技术检测大鼠心肌细胞L-型钙通道的电流密度和动力学.结果 丹参酮Ⅱ-A对L-型钙通道有抑制作用.在0μmol/L、10 μmol/L、20μmol/L和40μmol/L丹参酮Ⅱ-A作下,L-型钙通道的峰值电流密度分别为-13.34±1.06 pA/pF、-10.46 ±0.75 pA/pF、-7.62±0.50 PA/pF和-4.69±0.18 PA/pF,其抑制率分别为28.40%、52.14%和73.50% (n=8,P<0.05).结论 丹参酮Ⅱ-A抑制大鼠心肌细胞L-型钙通道,降低L-型钙通道的电流密度,呈浓度依赖性.%Objective To investigate the effect of Tanshinone Ⅱ -A on L-type calcium channel in isolated rat ventricular myocytes. Methods rat ventricular myocytes were isolated by enzymatic method, whole cell patch clamp technique was used to record the current and gating. Result Tanshinone Ⅱ-A inhibit L-type calcium channel current density. Tanshinone Ⅱ -A at μmol/L, 10μmol/L, 20μmol/L and 40 μmol/L,peak L-type calcium channel current density(Ica-L) were -13.34± 1.06 pA/pF, -10.46±0.75 pA/pF, -7.62±0.50 pA/pF and -4.69 ±0.18 pA/pF respectively, the inhibition rates were 28.40%, 52.14% and 73.50% respectively (n=8,P<0.05). Conclusion Effect of Tanshinone Ⅱ-A on rat cardiac myocytes L-type calcium current was significantly inhibited.

  15. Effects of tumor necrosis factor-alpha on calcium movement in rat ventricular myocytes%肿瘤坏死因子α对大鼠心室肌细胞钙转运的影响

    Institute of Scientific and Technical Information of China (English)

    李小强; 招明高; 梅其柄; 张延凤; 曹蔚; 王海芳; 陈丹; 崔毅

    2003-01-01

    AIM: To study the effects of tumor necrosis factor-alpha (TNF-α) on calcium movement in rat ventricular myocytes. METHODS: Intracellular free Ca2+ concentration was measured with calcium fluorescent probe Fluo-3/AM and laser confocal microscope. L-type calcium current (Ica,L) was recorded with the whole-cell configuration of the patch-clamp techniques. RESULTS: At 2, 20 and 200 μg/L, TNF-α was found to increase intracellular free Ca2+ concentration in a dose-dependent manner illustrated by the increment of calcium fluorescence density with laser confocal microscope. Nicardipine 0.5 μmol/L slightly attenuated TNF-α-induced response. When the cardiac myocytes were exposed to caffeine (100 mmol/L) for 30 min, TNF-α failed to induce any change of intracellular free calcium. However, it was found that TNF-α inhibited Ica,L in whole-cell patch-clamp experiments. At 2, 20, and 200 μg/L, TNF-α decreased peak Ica,L by 3.9 % (-5.1 pA/pF+0.3 pA/pF vs -4.9 pA/pF+0.2 pA/pF, n=9, P>0.05), 15.7 % (-5.1 pA/pF+0.3 pA/pF vs -4.3 pA/pF+0.3 pA/pF, n=9, P<0.05) and 19.6 % (-5.1 pA/pF+0.3 pA/ pF vs -4.1 pA/pF+0.4 pA/pF, n=9, P<0.01), respectively. It shifted the steady-state inactivation curve of Ica,L to the left (V1/2 shifted from -28.7 mV+0.3 mV to -37.8 mV+1.4 mV, n=7, P<0.05), while it took no effects on steadystate activation and recovery from inactivation. CONCLUSION: TNF-α inhibited Ica,L in rat ventricular myocytes,while increasing the intercellular free Ca2+ level due to the release of Ca2+ from intracellular stores.

  16. Cardiac applications of optogenetics.

    Science.gov (United States)

    Ambrosi, Christina M; Klimas, Aleksandra; Yu, Jinzhu; Entcheva, Emilia

    2014-08-01

    In complex multicellular systems, such as the brain or the heart, the ability to selectively perturb and observe the response of individual components at the cellular level and with millisecond resolution in time, is essential for mechanistic understanding of function. Optogenetics uses genetic encoding of light sensitivity (by the expression of microbial opsins) to provide such capabilities for manipulation, recording, and control by light with cell specificity and high spatiotemporal resolution. As an optical approach, it is inherently scalable for remote and parallel interrogation of biological function at the tissue level; with implantable miniaturized devices, the technique is uniquely suitable for in vivo tracking of function, as illustrated by numerous applications in the brain. Its expansion into the cardiac area has been slow. Here, using examples from published research and original data, we focus on optogenetics applications to cardiac electrophysiology, specifically dealing with the ability to manipulate membrane voltage by light with implications for cardiac pacing, cardioversion, cell communication, and arrhythmia research, in general. We discuss gene and cell delivery methods of inscribing light sensitivity in cardiac tissue, functionality of the light-sensitive ion channels within different types of cardiac cells, utility in probing electrical coupling between different cell types, approaches and design solutions to all-optical electrophysiology by the combination of optogenetic sensors and actuators, and specific challenges in moving towards in vivo cardiac optogenetics.

  17. Inhibitory effects of hesperetin on Kv1.5 potassium channels stably expressed in HEK 293 cells and ultra-rapid delayed rectifier K(+) current in human atrial myocytes.

    Science.gov (United States)

    Wang, Huan; Wang, Hong-Fei; Wang, Chen; Chen, Yu-Fang; Ma, Rong; Xiang, Ji-Zhou; Du, Xin-Ling; Tang, Qiang

    2016-10-15

    In the present study, the inhibitory effects of hesperetin (HSP) on human cardiac Kv1.5 channels expressed in HEK 293 cells and the ultra-rapid delayed rectifier K(+) current (Ikur) in human atrial myocytes were examined by using the whole-cell configuration of the patch-clamp techniques. We found that hesperetin rapidly and reversibly suppressed human Kv1.5 current in a concentration dependent manner with a half-maximal inhibition (IC50) of 23.15 μΜ with a Hill coefficient of 0.89. The current was maximally diminished about 71.36% at a concentration of 300μM hesperetin. Hesperetin significantly positive shifted the steady-state activation curve of Kv1.5, while negative shifted the steady-state inactivation curve. Hesperetin also accelerated the inactivation and markedly slowed the recovery from the inactivation of Kv1.5 currents. Block of Kv1.5 currents by hesperetin was in a frequency dependent manner. However, inclusion of 30μM hesperetin in pipette solution produced no effect on Kv1.5 channel current, while the current were remarkable and reversibly inhibited by extracellular application of 30μM hesperetin. We also found that hesperetin potently and reversibly inhibited the ultra-repaid delayed K(+) current (Ikur) in human atrial myocytes, which is in consistent with the effects of hesperetin on Kv1.5 currents in HEK 293 cells. In conclusion, hesperetin is a potent inhibitor of Ikur (which is encoded by Kv1.5), with blockade probably due to blocking of both open state and inactivated state channels from outside of the cell.

  18. Effects of astragaloside Ⅳ on electrocardiogram and action potential of ventricular myocytes in guinea pigs%黄芪甙Ⅳ对豚鼠心电图及心室肌动作电位的影响

    Institute of Scientific and Technical Information of China (English)

    周云; 王俊杰; 赵伟; 张川; 张卫东

    2009-01-01

    Objective To observe the effects of astragaloside Ⅳ on electrocardiogram (ECG) and action potential of ventricular myocytes in guinea pigs. Methods ECG was recorded in vivo and ex vivo by using conventional ECG recording method from anesthetic guinea pigs and Langendoff perfusion model of hearts. Action potentials were recorded from isolated papillary muscles of right ventricles of guinea pigs by using microelectrode techniques. Results RR interval was prolonged by Astragaloside Ⅳ in a dose-dependent manner both in vivo and ex vivo. Astragaloside Ⅳ shortened action potential duration (APD), while had no effects on resting potential, action potential amplitude and maximal rate of depolarization. Conclusion Astragaloside Ⅳ exerts a negative chronotropic effect on heart and shortens APD of cardiac myocytes, which may be involved with calcium channels.%目的 观察黄芪甙Ⅳ对豚鼠心电图(ECG)及心室肌动作电位的影响.方法 分别在麻醉豚鼠和Langendoff心脏灌流模型上记录体表ECG和离体心脏ECG,采用细胞内微电极技术记录豚鼠右心室乳头肌的动作电位.结果 黄芪甙Ⅳ能延长豚鼠体表ECG和离体心脏ECG的RR间期,这一效应具有剂量依赖性.黄芪甙Ⅳ还能缩短动作电位的时程(APD),但对静息电位、动作电位幅度和最大去极速度没有明显影响.结论 黄芪甙Ⅳ具有负性变时作用,能缩短心肌细胞APD,其作用机制可能与慢钙通道有关.

  19. Enabling microscale and nanoscale approaches for bioengineered cardiac tissue.

    Science.gov (United States)

    Chan, Vincent; Raman, Ritu; Cvetkovic, Caroline; Bashir, Rashid

    2013-03-26

    In this issue of ACS Nano, Shin et al. present their finding that the addition of carbon nanotubes (CNT) in gelatin methacrylate (GelMA) results in improved functionality of bioengineered cardiac tissue. These CNT-GelMA hybrid materials demonstrate cardiac tissue with enhanced electrophysiological performance; improved mechanical integrity; better cell adhesion, viability, uniformity, and organization; increased beating rate and lowered excitation threshold; and protective effects against cardio-inhibitory and cardio-toxic drugs. In this Perspective, we outline recent progress in cardiac tissue engineering and prospects for future development. Bioengineered cardiac tissues can be used to build "heart-on-a-chip" devices for drug safety and efficacy testing, fabricate bioactuators for biointegrated robotics and reverse-engineered life forms, treat abnormal cardiac rhythms, and perhaps one day cure heart disease with tissue and organ transplants.

  20. A modified FitzHugh-Nagumo model for cardiac instabilities: The replacement of a conductance variable with Ca current as a slow variable

    Science.gov (United States)

    Osaka, Motohisa

    2013-02-01

    The FitzHugh-Nagumo model of nerve conduction is also used as a model of cardiac excitability. We propose the replacement of a gating variable of the conductance of K+ current with Ca2+ current as a slow variable of the model, in which plays a key role in the cardiac action potential. Since ion currents conduct transversely as well as longitudinally through gap junctions between myocytes, particularly in ischemia, a respective diffusion term is involved to both equations of a fast variable and a slow variable. We show that only a small increase of a coefficient of the diffusion term of Ca2+ current may cause cardiac instabilities, which are presumed to cause breakup of conduction and finally a lethal arrhythmia, ventricular fibrillation. Particularly, these instabilities do not occur without the diffusion term of Ca2+ current.

  1. Aerobic interval training partly reverse contractile dysfunction and impaired Ca2+ handling in atrial myocytes from rats with post infarction heart failure.

    Directory of Open Access Journals (Sweden)

    Anne Berit Johnsen

    Full Text Available BACKGROUND: There is limited knowledge about atrial myocyte Ca(2+ handling in the failing hearts. The aim of this study was to examine atrial myocyte contractile function and Ca(2+ handling in rats with post-infarction heart failure (HF and to examine whether aerobic interval training could reverse a potential dysfunction. METHODS AND RESULTS: Post-infarction HF was induced in Sprague Dawley rats by ligation of the left descending coronary artery. Atrial myocyte shortening was depressed (p<0.01 and time to relaxation was prolonged (p<0.01 in sedentary HF-rats compared to healthy controls. This was associated with decreased Ca(2+ amplitude, decreased SR Ca(2+ content, and slower Ca(2+ transient decay. Atrial myocytes from HF-rats had reduced sarcoplasmic reticulum Ca(2+ ATPase activity, increased Na(+/Ca(2+-exchanger activity and increased diastolic Ca(2+ leak through ryanodine receptors. High intensity aerobic interval training in HF-rats restored atrial myocyte contractile function and reversed changes in atrial Ca(2+ handling in HF. CONCLUSION: Post infarction HF in rats causes profound impairment in atrial myocyte contractile function and Ca(2+ handling. The observed dysfunction in atrial myocytes was partly reversed after aerobic interval training.

  2. BIN1 localizes the L-type calcium channel to cardiac T-tubules.

    Directory of Open Access Journals (Sweden)

    Ting-Ting Hong

    2010-02-01

    Full Text Available The BAR domain protein superfamily is involved in membrane invagination and endocytosis, but its role in organizing membrane proteins has not been explored. In particular, the membrane scaffolding protein BIN1 functions to initiate T-tubule genesis in skeletal muscle cells. Constitutive knockdown of BIN1 in mice is perinatal lethal, which is associated with an induced dilated hypertrophic cardiomyopathy. However, the functional role of BIN1 in cardiomyocytes is not known. An important function of cardiac T-tubules is to allow L-type calcium channels (Cav1.2 to be in close proximity to sarcoplasmic reticulum-based ryanodine receptors to initiate the intracellular calcium transient. Efficient excitation-contraction (EC coupling and normal cardiac contractility depend upon Cav1.2 localization to T-tubules. We hypothesized that BIN1 not only exists at cardiac T-tubules, but it also localizes Cav1.2 to these membrane structures. We report that BIN1 localizes to cardiac T-tubules and clusters there with Cav1.2. Studies involve freshly acquired human and mouse adult cardiomyocytes using complementary immunocytochemistry, electron microscopy with dual immunogold labeling, and co-immunoprecipitation. Furthermore, we use surface biotinylation and live cell confocal and total internal fluorescence microscopy imaging in cardiomyocytes and cell lines to explore delivery of Cav1.2 to BIN1 structures. We find visually and quantitatively that dynamic microtubules are tethered to membrane scaffolded by BIN1, allowing targeted delivery of Cav1.2 from the microtubules to the associated membrane. Since Cav1.2 delivery to BIN1 occurs in reductionist non-myocyte cell lines, we find that other myocyte-specific structures are not essential and there is an intrinsic relationship between microtubule-based Cav1.2 delivery and its BIN1 scaffold. In differentiated mouse cardiomyocytes, knockdown of BIN1 reduces surface Cav1.2 and delays development of the calcium transient

  3. Characterization and Differentiation into Adipocytes and Myocytes of Porcine Bone Marrow Mesenchymal Stem Cells

    Institute of Scientific and Technical Information of China (English)

    DU Min-qing; WANG Song-bo; JIANG Qing-yan; HUANG Yue-qin; LU Nai-Sheng; SHU Gang; ZHU Xiao-tong; WANG Li-na; GAO Ping; XI Qian-yun; ZHANG Yong-liang

    2014-01-01

    Bone marrow mesenchymal stem cells (BMSCs) could differentiate into various cell types including adipocytes and myocytes, which had important scientiifc signiifcance not only in the ifeld of tissue regeneration, but also in the ifeld of agricultural science. In an attempt to exhibit the characterization and differentiation into adipocytes and myocytes of porcine BMSCs, we isolated and puriifed porcine BMSCs by red blood cell lysis method and percoll gradient centrifugation. The puriifed cells presented a stretched ifbroblast-like phenotype when adhered to the culture plate. The results of lfow cytometry analysis and immunofluorescence staining demonstrated that the isolated cells were positive for mesenchymal surface markers CD29, CD44 and negative for hematopoietic markers CD45 and the adhesion molecules CD31. Cells were induced to differentiate into adipocytes with adipogenic medium containing insulin, dexamethasone, oleate and octanoate. Oil Red O staining demonstrated that the porcine BMSCs successfully differentiated to adipocytes. Moreover, the ifndings of real-time PCR and Western blotting indicated that the induced cells expressed adipogenic marker genes (PPAR-γ, C/EBP-α, perilipin, aP2) mRNA or proteins (PPAR-γ, perilipin, aP2). On the other hand, porcine BMSCs were induced into myoctyes with myogenic medium supplemented with 5-azacytidine, basic ifbroblast growth factor, chick embryo extract and horse serum. Morphological observation by hochest 33342 staining showed that the induced cells presented as multi-nucleus muscular tube structure. And myogenic marker genes (Myf5, desmin) mRNA or proteins (Myf5, MyoD, myogenin, desmin) were found in the induced cells. In addition, the results of immunolfuorescence staining revealed that myogenic marker (Myf5, MyoD, myogenin, desmin, S-MyHC) proteins was positive in the induced cells. Above all, these results suggested that the isolated porcine BMSCs were not only consistent with the characterization of

  4. Effect of resveratrol on L-type calcium current in rat ventricular myocytes

    Institute of Scientific and Technical Information of China (English)

    Li-ping ZHANG; Jing-xiang YIN; Zheng LIU; Yi ZHANG; Qing-shan WANG; Juan ZHAO

    2006-01-01

    Aim: To study the effect of resveratrol on L-type calcium current (ICa-L) in isolated rat ventricular myocytes and the mechanisms underlying these effects. Methods:ICa-L was examined in isolated single rat ventricular myocytes by using the whole cell patch-clamp recording technique. Results: Resveratrol (10-40 μmol/L) reduced the peak amplitude of ICa-L and shifted the current-voltage (I-V) curve upwards in a concentration-dependent manner. Resveratrol (10, 20, 40 μmol/L)decreased the peak amplitude of ICa-L from -14.2± 1.5 pA/pF to -10.5± 1.5 pA/pF (P<0.05), -7.5±2.4 pA/pF (P<0.01), and -5.2±1.2 pA/pF (P<0.01), respectively.Resveratrol (40 μmol/L) shifted the steady-state activation curve of ICa-L to the right and changed the half-activation potential (V0.5) from -19.4±0.4 mV to -15.4±1.9 mV (P<0.05). Resveratrol at a concentration of 40 μmol/L did not affect the steady-state inactivation curve of ICa-L, but did markedly shift the timedependent recovery curve of ICa-L to the right, and slow down the recovery of ICa-L from inactivation. Sodium orthovanadate (Na3VO4; 1 mmol/L), a potent inhibitor of tyrosine phosphatase, significantly inhibited the effects of resveratrol (P<0.01). Conclusion: Resveratrol inhibited ICa- L mainly by inhibiting the activation of L-type calcium channels and slowing down the recovery of L-type calcium channels from inactivation. This inhibitory effect of resveratrol was mediated by the inhibition of protein tyrosine kinase in rat ventricular myocytes.

  5. Dihydroxyflavonol reduces post-infarction left ventricular remodeling by preventing myocyte apoptosis in the non-infarcted zone in goats

    Institute of Scientific and Technical Information of China (English)

    WANG Sheng; FEI Ke; XU Ya-wei; WANG Liang-xu; Chen Yan-qin

    2009-01-01

    Background Myocyte apoptosis is considered to be the major causative factor of left ventricular (LV) remodeling following myocardial infarction (MI). We previously reported that 3', 4'-dihydroxyflavonol (DiOHF), was able to suppress oxidative stress and preserve the expression of endothelial nitric oxide synthase during myocardial reperfusion injury, which may benefit the reduction of myocyte apoptosis. We therefore aimed to evaluate the potential actions of DiOHF against myocyte apoptosis and post-infarction LV remodeling in this study. Methods Following experimental MI, surgical instrumented goats were randomly assigned into vehicle and DiOHF (2 mg/kg; i.v., daily) groups to receive 4 weeks of reperfusion with corresponding treatments. LV pressure recordings and echocardiogram were performed at baseline, 2 and 4 weeks of reperfusion. Myocardial tissues were collected in the end to determine infarct size and apoptosis related assays. Results LV end-diastolic volume and diameter were significantly increased 4 weeks after MI in the vehicle group, accompanied by reduced posterior wall thickness, septal thickness and LV mass, whereas those changes were markedly prevented by DiOHF treatment. Similarly, significantly reduced infarct size was found in DiOHF group as compared to vehicle group, and DiOHF dramatically inhibited the increase in LV end-diastolic pressure and the reductions in ejection fraction, fraction shortening and dP/dtmax. Moreover, DiOHF treatment significantly reduced the extent of myocyte apoptosis detected by TUNEL assay, enhanced the protein expression of caspase-3, Fas, Bax and cytochrome c in the non-infarcted myocardium in comparison to vehicle. Conclusions Daily DiOHF treatment during the reperfusion period after MI in the ovine hearts markedly reduced the magnitude of post-infarction LV remodeling through the inhibition of myocyte apoptosis in the remote non-infarcted myocardium.

  6. Regulation of LXR by fatty acids, insulin, growth hormone and tumor necrosis factor-α in rainbow trout myocytes.

    Science.gov (United States)

    Cruz-Garcia, Lourdes; Sánchez-Gurmaches, Joan; Gutiérrez, Joaquim; Navarro, Isabel

    2011-10-01

    The liver X receptor (LXR) has recently been described in salmonids. In mammals, this receptor is already known as a transcriptional factor that regulates diverse aspects of cholesterol, fatty acid and carbohydrate metabolism in various tissues, including muscle. Here we examined LXR in trout myocytes. For this purpose, we analyzed LXR target gene expression and gene profile during myocyte development. In addition, we studied the transcriptional regulation of LXR by hormones, a pro-inflammatory mediator and unsaturated fatty acids. Trout myocytes were incubated with LXR agonists (T091317, 22(R)-hydroxycholesterol) and unsaturated fatty acids for 24h. Furthermore, differentiated myocytes were incubated with insulin and growth hormone (GH) for 3h, 6h and 18h, and with tumor necrosis factor-α (TNFα) for 24h. Samples were also obtained in various stages of cell differentiation. Our results demonstrate that lipoprotein lipase (LPL), fatty acid synthase (FAS), ATP-binding cassette transporter A1 (ABCA1), peroxisome proliferator-activated receptor-α and β (PPARα, β) are target genes of LXR in trout muscle. LXR agonists increased LXR expression, thereby indicating that this receptor is autoregulated. Unsaturated fatty acids downregulated LXR gene expression. This observation suggests a regulatory mechanism of these molecules on LXR-mediated fatty acid synthesis and uptake. TNFα did not modulate LXR gene transcription. Expression of the LXR gene was activated by insulin and GH. These results suggest that LXR may play a lipogenic role through insulin stimulation and a tendency to promote anabolic effects through GH on trout myocytes.

  7. Carbon Monoxide Induces Cardiac Arrhythmia via Induction of the Late Na+ Current

    Science.gov (United States)

    Dallas, Mark L.; Yang, Zhaokang; Boyle, John P.; Boycott, Hannah E.; Scragg, Jason L.; Milligan, Carol J.; Elies, Jacobo; Duke, Adrian; Thireau, Jérôme; Reboul, Cyril; Richard, Sylvain; Bernus, Olivier; Steele, Derek S.

    2012-01-01

    Rationale: Clinical reports describe life-threatening cardiac arrhythmias after environmental exposure to carbon monoxide (CO) or accidental CO poisoning. Numerous case studies describe disruption of repolarization and prolongation of the QT interval, yet the mechanisms underlying CO-induced arrhythmias are unknown. Objectives: To understand the cellular basis of CO-induced arrhythmias and to indentify an effective therapeutic approach. Methods: Patch-clamp electrophysiology and confocal Ca2+ and nitric oxide (NO) imaging in isolated ventricular myocytes was performed together with protein S-nitrosylation to investigate the effects of CO at the cellular and molecular levels, whereas telemetry was used to investigate effects of CO on electrocardiogram recordings in vivo. Measurements and Main Results: CO increased the sustained (late) component of the inward Na+ current, resulting in prolongation of the action potential and the associated intracellular Ca2+ transient. In more than 50% of myocytes these changes progressed to early after-depolarization–like arrhythmias. CO elevated NO levels in myocytes and caused S-nitrosylation of the Na+ channel, Nav1.5. All proarrhythmic effects of CO were abolished by the NO synthase inhibitor l-NAME, and reversed by ranolazine, an inhibitor of the late Na+ current. Ranolazine also corrected QT variability and arrhythmias induced by CO in vivo, as monitored by telemetry. Conclusions: Our data indicate that the proarrhythmic effects of CO arise from activation of NO synthase, leading to NO-mediated nitrosylation of NaV1.5 and to induction of the late Na+ current. We also show that the antianginal drug ranolazine can abolish CO-induced early after-depolarizations, highlighting a novel approach to the treatment of CO-induced arrhythmias. PMID:22822026

  8. Activation and modulation of cardiac poly-adenosine diphosphate ribose polymerase activity in a rat model of brain death.

    Science.gov (United States)

    Brain, John G; Rostron, Anthony J; Dark, John H; Kirby, John A

    2008-05-15

    DNA damage during transplantation can activate poly-adenosine diphosphate ribose polymerase (PARP) resulting in the generation of polymers of adenosine diphosphate-ribose (PAR). Excessive linkage of PAR to nuclear proteins can induce cell death, thereby limiting the function of transplanted organs. This study uses a rat model of brain death to determine the profile of PARP activation and whether mechanisms that lead to cell death can be ameliorated by appropriate donor resuscitation. The expression of PAR-linked nuclear proteins within cardiac myocytes was greatly increased after the induction of donor brain death. Importantly, infusion of noradrenaline or vasopressin to normalize the chronic hypotension produced by brain death reduced the expression of PAR to a level below baseline. These data suggest that chronic hypotension after donor brain death has the potential to limit cardiac function through the activation of PARP; however, this early cause of graft damage can be mitigated by appropriate donor resuscitation.

  9. [Andersen-Tawil syndrome: a review of its clinical and genetic diagnosis with emphasis on cardiac manifestations].

    Science.gov (United States)

    Márquez, Manlio F; Totomoch-Serra, Armando; Vargas-Alarcón, Gilberto; Cruz-Robles, David; Pellizzon, Oscar A; Cárdenas, Manuel

    2014-01-01

    The Andersen-Tawil syndrome is a cardiac ion channel disease that is inherited in an autosomal dominant way and is classified as type 7 of the congenital long QT syndromes. Affected gene is KCNJ2, which forms the inward rectifier potassium channel designated Kir2.1. This protein is involved in stabilizing the resting membrane potential and controls the duration of the action potential in skeletal muscle and heart. It also participates in the terminal repolarization phase of the action potential in ventricular myocytes and is a major component responsible for the correction in the potassium current during phase 3 of the action potential repolarization. Kir 2.1 channel has a predominant role in skeletal muscle, heart and brain. Alterations in this channel produce flaccid paralysis, arrhythmias, impaired skeletal development primarily in extremities and facial area. In this review we address the disease from the point of view of clinical and molecular diagnosis with emphasis on cardiac manifestations.

  10. [Psychosomatic aspects of cardiac arrhythmias].

    Science.gov (United States)

    Siepmann, Martin; Kirch, Wilhelm

    2010-07-01

    Emotional stress facilitates the occurrence of cardiac arrhythmias including sudden cardiac death. The prevalence of anxiety and depression is increased in cardiac patients as compared to the normal population. The risk of cardiovascular mortality is enhanced in patients suffering from depression. Comorbid anxiety disorders worsen the course of cardiac arrhythmias. Disturbance of neurocardiac regulation with predominance of the sympathetic tone is hypothesized to be causative for this. The emotional reaction to cardiac arrhythmias is differing to a large extent between individuals. Emotional stress may result from coping with treatment of cardiac arrhythmias. Emotional stress and cardiac arrhythmias may influence each other in the sense of a vicious circle. Somatoform cardiac arrhythmias are predominantly of psychogenic origin. Instrumental measures and frequent contacts between physicians and patients may facilitate disease chronification. The present review is dealing with the multifaceted relationships between cardiac arrhythmias and emotional stress. The underlying mechanisms and corresponding treatment modalities are discussed.

  11. Satellite cells derived from obese humans with type 2 diabetes and differentiated into myocytes in vitro exhibit abnormal response to IL-6.

    Directory of Open Access Journals (Sweden)

    Camilla Scheele

    Full Text Available Obesity and type 2 diabetes are associated with chronically elevated systemic levels of IL-6, a pro-inflammatory cytokine with a role in skeletal muscle metabolism that signals through the IL-6 receptor (IL-6Rα. We hypothesized that skeletal muscle in obesity-associated type 2 diabetes develops a resistance to IL-6. By utilizing western blot analysis, we demonstrate that IL-6Rα protein was down regulated in skeletal muscle biopsies from obese persons with and without type 2 diabetes. To further investigate the status of IL-6 signaling in skeletal muscle in obesity-associated type 2 diabetes, we isolated satellite cells from skeletal muscle of people that were healthy (He, obese (Ob or were obese and had type 2 diabetes (DM, and differentiated them in vitro into myocytes. Down-regulation of IL