Nuclear ion channels in cardiac myocytes

1992 ◽  
Vol 421 (5) ◽  
pp. 473-485 ◽  
Author(s):  
J. Omar Bustamante
Keyword(s):  
Ion Channels ◽  
Cardiac Myocytes ◽  
Nuclear Ion Channels

Nuclear ion channel activity is regulated by actin filaments

1996 ◽  
Vol 270 (5) ◽  
pp. C1532-C1543 ◽  
Author(s):  
A. G. Prat ◽  
H. F. Cantiello
Keyword(s):  
Ion Channels ◽  
Actin Cytoskeleton ◽  
Nuclear Envelope ◽  
Ion Channel ◽  
Actin Filaments ◽  
Actin Binding ◽  
Bathing Solution ◽  
Channel Activity ◽  
Nuclear Ion Channels ◽  
Inside Out

Actin filaments are novel second messengers involved in ion channel regulation. Because cytoskeletal components interact with the nuclear envelope, the actin cytoskeleton may also control nuclear membrane function. In this report, the patch-clamp technique was applied to isolated nuclei from amphibian A6 epithelial cells to assess the role of actin filaments on nuclear ion channel activity under nucleus-attached or -excised conditions. The most prevalent spontaneous nuclear ion channel species, 76% (n = 46), was cation selective and had a maximal single-channel conductance of approximately 420 pS. Nuclear ion channels also displayed multiple subconductance states, including channel activity of 26 pS that was frequently observed. Nuclear ion channel activity on otherwise quiescent patches was induced by either addition of the actin cytoskeleton disrupter cytochalasin D (CD; 5 micrograms/ml, 60%, 3 of 5 patches) or actin (10-1,000 micrograms/ml) to the bathing solution of nucleus-attached patches (59%, 13 of 22 patches). Actin also induced ion channel activity in quiescent excised inside-out patches from the nuclear envelope (80%, 4 of 5 patches). In contrast, addition of bovine serum albumin (10-1,000 micrograms/ml) to the bathing solution of nucleus-attached patches was without effect on nuclear ion channel activity (5 of 5 patches). The monoclonal antibody MAb414, specific for nuclear pore complex proteins, completely prevented either spontaneous or cytosolic actin-induced nuclear ion channels under nucleus-attached conditions (4 of 4 patches) but not intranuclear actin-induced nuclear ion channels under excised inside-out conditions (3 of 3 patches). In nucleus-attached patches, channel activity was readily activated by addition of the G-actin-binding protein deoxyribonuclease I to nucleus-attached patches (56%, 5 of 9 patches) or further addition of the actin-cross-linker filamin in the presence of actin (57%, 4 of 7 patches). The data indicate that dynamic changes in actin filament organization may represent a novel mechanism to control nuclear function.

Dynamic of Ion Channel Expression at the Plasma Membrane of Cardiomyocytes

2012 ◽  
Vol 92 (3) ◽  
pp. 1317-1358 ◽  
Author(s):  
Elise Balse ◽  
David F. Steele ◽  
Hugues Abriel ◽  
Alain Coulombe ◽  
David Fedida ◽  
...  
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Cardiac Myocytes ◽  
Cardiac Myocyte ◽  
Membrane Lipids ◽  
Current Knowledge ◽  
Small Gtpases ◽  
Molecular Organization ◽  
Cardiac Sarcolemma ◽  
Channel Expression

Cardiac myocytes are characterized by distinct structural and functional entities involved in the generation and transmission of the action potential and the excitation-contraction coupling process. Key to their function is the specific organization of ion channels and transporters to and within distinct membrane domains, which supports the anisotropic propagation of the depolarization wave. This review addresses the current knowledge on the molecular actors regulating the distinct trafficking and targeting mechanisms of ion channels in the highly polarized cardiac myocyte. In addition to ubiquitous mechanisms shared by other excitable cells, cardiac myocytes show unique specialization, illustrated by the molecular organization of myocyte-myocyte contacts, e.g., the intercalated disc and the gap junction. Many factors contribute to the specialization of the cardiac sarcolemma and the functional expression of cardiac ion channels, including various anchoring proteins, motors, small GTPases, membrane lipids, and cholesterol. The discovery of genetic defects in some of these actors, leading to complex cardiac disorders, emphasizes the importance of trafficking and targeting of ion channels to cardiac function. A major challenge in the field is to understand how these and other actors work together in intact myocytes to fine-tune ion channel expression and control cardiac excitability.

Cardiac Chloride Currents

Physiology ◽  
1996 ◽  
Vol 11 (4) ◽  
pp. 175-181 ◽  
Author(s):  
RD Harvey
Keyword(s):  
Ion Channels ◽  
Electrical Activity ◽  
Cardiac Myocytes ◽  
Heart Cells ◽  
Chloride Currents ◽  
Cl Conductance

Heart cells possess a number of different ion channels, most of which are cation selective. However, several Cl- conductance pathways have recently been identified. This article describes some of the different Cl- currents found in mammalian cardiac myocytes and discusses their likely contribution to the electrical activity of the heart.

scholarly journals Expression of TRP Ion Channels in Cardiac Myocytes

2015 ◽  
Vol 29 (S1) ◽  
Author(s):  
Spencer Andrei ◽  
Ian Bratz ◽  
Derek Damron
Keyword(s):  
Ion Channels ◽  
Cardiac Myocytes ◽  
Trp Ion Channels

Cardiac myocytes cultured on a basement membrane extract of the ehs tumor

1986 ◽  
Vol 44 ◽  
pp. 270-271
Author(s):  
L. Terracio ◽  
A. Dewey ◽  
K. Rubin ◽  
T.K. Borg
Keyword(s):  
Extracellular Matrix ◽  
Basement Membrane ◽  
Cardiac Myocytes ◽  
Normal Tissue ◽  
Cell Spreading ◽  
Collagen Iv ◽  
Basement Membrane Extract ◽  
Membrane Extract ◽  
Growth Development ◽  
Multicellular Organisms

The recognition and interaction of cells with the extracellular matrix (ECM) effects the normal physiology as well as the pathology of all multicellular organisms. These interactions have been shown to influence the growth, development, and maintenance of normal tissue function. In previous studies, we have shown that neonatal cardiac myocytes specifically interacts with a variety of ECM components including fibronectin, laminin, and collagens I, III and IV. Culturing neonatal myocytes on laminin and collagen IV induces an increased rate of both cell spreading and sarcomerogenesis.

Application of stereological analysis of cell volume to isolated myocytes in culture with and without adrenergic innervation

1990 ◽  
Vol 48 (3) ◽  
pp. 416-417
Author(s):  
Jane K. Rosenthal ◽  
Dianne L. Atkins ◽  
William J. Marvin ◽  
Penny A. Krumm
Keyword(s):  
Cardiac Myocytes ◽  
Structural Changes ◽  
Three Dimensional ◽  
Adrenergic Innervation ◽  
Culture Cell ◽  
Serial Sections ◽  
Newborn Rats ◽  
Primary Culture Cell ◽  
Biological Studies ◽  
Cell Volumes

To comprehend structural changes in cardiac myocytes accompanying adrenergic innervation, it is essential that a three dimensional analysis be performed. To date, biological studies which utilize stereological methods have been limited to cells in tissue and in organs. Our laboratory has utilized current stereological techniques for measuring absolute volumes of individual myocytes in primary culture. Cell volumes are calculated for two distinct groups of cells at 96 hours in culture: isolated myocytes and myocytes innervated with adrenergic neurons (Figure 1).Cardiac myocytes are cultured from the ventricular apices of newborn rats. Cells are plated directly onto tissue culture dishes with or without preplated explants from the paravertebral thoracolumbar sympathetic chain. On day four cultures are photographed and marked for one-to-one cell location. Following conventional fixation and embeddment in eponate-12, the cells are relocated and mounted for microtomy. The cells are completely sectioned at 120nm in their parallel orientation to the surface of the dish (Figure 2). Serial sections are collected on formvar coated slotted grids and are recorded in sequence.

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