Mitochondrial and sarcolemmal Ca2+ transport reduce [Ca2+]i during caffeine contractures in rabbit cardiac myocytes.

A role for Ca2+-calmodulin-dependent kinase (CamK) in regulation of the voltage-sensitive release mechanism (VSRM) was investigated in guinea pig ventricular myocytes. Voltage clamp was used to separate the VSRM from Ca2+-induced Ca2+release (CICR). VSRM contractions and Ca2+ transients were absent in cells dialyzed with standard pipette solution but present when 2–5 μM calmodulin was included. Effects of calmodulin were blocked by KN-62 (CamK inhibitor), but not H-89, a protein kinase A (PKA) inhibitor. Ca2+ current and caffeine contractures were not affected by calmodulin. Transient-voltage relations were bell-shaped without calmodulin, but they were sigmoidal and typical of the VSRM with calmodulin. Contractions with calmodulin exhibited inactivation typical of the VSRM. These contractions were inhibited by rapid application of 200 μM of tetracaine, but not 100 μM of Cd2+, whereas CICR was inhibited by Cd2+ but not tetracaine. In undialyzed myocytes (high-resistance microelectrodes), KN-62 or H-89 each reduced amplitudes of VSRM contractions by ∼50%, but together they decreased VSRM contractions by 93%. Thus VSRM is facilitated by CamK or PKA, and both pathways regulate the VSRM in undialyzed cells.

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100142979 ◽

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.

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015962x ◽

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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