Search results for "Myocyte"
showing 10 items of 248 documents
Two cases of adynamia episodica hereditaria: In vitro investigation of muscle cell membrane and contraction parameters
1983
Membrane potentials, current-voltage relationships, and contractile parameters were studied in intact muscle cell bundles obtained from two patients with adynamia episodica hereditaria. In a normal extracellular medium, the cell membranes had resting potentials of about -80 mV and their current-voltage relationships were not significantly different from control curves. In contrast to normal muscles the afflicted cells were paralyzed in a medium having 6-10 mmol/liter potassium. The mechanisms of paralysis in the two specimens were different from each other. Many fibers from one patient were spontaneously active even in normal solution. In high potassium solution spontaneous activity was inc…
Discoordinate regulation of different K channels in cultured rat skeletal muscle by nerve growth factor
1999
We investigated the effects of nerve growth factor (NGF) on expression of K+ channels in cultured skeletal muscle. The channels studied were (1) charybdotoxin (ChTx)-sensitive channels by using a polyclonal antibody raised in rabbits against ChTx, (2) Kv1.5 voltage-sensitive channels, and (3) apamin-sensitive (afterhyperpolarization) channels. Crude homogenates were prepared from cultures made from limb muscles of 1-2-day-old rat pups for identification of ChTx-sensitive and Kv1.5 channels by Western blotting techniques. Apamin-sensitive K+ channels were studied by measurement of specific [125I]-apamin binding by whole cell preparations. ChTx-sensitive channels display a fusion-related incr…
Atrial natriuretic peptide and CD34 overexpression in human idiopathic dilated cardiomyopathies.
2007
Idiopathic dilated cardiomyopathy (IDCM) is a primary myocardial disease of unknown cause characterized by ventricular chamber enlargement with impaired contractile function. In familial forms of IDCM, mutations of genes coding for cytoskeletal proteins related to force transmission, such as dystrophin, cardiac actin, desmin, and delta-sarcoglycan, have been identified. Here, we report the data of a retrospective investigation carried out to evaluate the expression of atrial natriuretic peptide (ANP), CD34, troponin T and nestin in the myocardium of patients affected with IDCM. Formalin-fixed and paraffin-embedded consecutive tissue sections from the ventricular wall of 10 human normal hear…
A microscope configuration for nanometer 3-D movement monitoring accuracy.
2011
In this paper we present a new microscopy configuration based upon temporal tracking of a secondary reflected speckle by imaging the speckle through properly defocused optics. The configuration is used to monitor three-dimensional (3-D) spontaneous contraction of rat cardiac muscle cells while achieving nanometer tracking accuracy at a rate of 30 frames per second (fps) without using interferometric recording. Estimation of the change in the optical path of accuracy of 50 nm in the transverse direction and of 200 nm in the axial direction was achieved.
Redox signaling (cross-talk) from and to mitochondria involves mitochondrial pores and reactive oxygen species
2010
This review highlights the important role of redox signaling between mitochondria and NADPH oxidases. Besides the definition and general importance of redox signaling, the cross-talk between mitochondrial and Nox-derived reactive oxygen species (ROS) is discussed on the basis of 4 different examples. In the first model, angiotensin-II is discussed as a trigger for NADPH oxidase activation with subsequent ROS-dependent opening of mitochondrial ATP-sensitive potassium channels leading to depolarization of mitochondrial membrane potential followed by mitochondrial ROS formation and respiratory dysfunction. This concept was supported by observations that ethidium bromide-induced mitochondrial d…
Endocytosis in skeletal muscle fibers.
1999
Defining the organization of endocytic pathway in multinucleated skeletal myofibers is crucial to understand the routing of membrane proteins, such as receptors and glucose transporters, through this system. Here we analyzed the organization of the endocytic trafficking pathways in isolated rat myofibers. We found that sarcolemmal-coated pits and transferrin receptors were concentrated in the I band areas. Fluid phase markers were taken up into vesicles in the same areas along the whole length of the fibers and were then delivered into structures around and between the nuclei. These markers also accumulated beneath the neuromuscular and myotendinous junctions. The recycling compartment, lab…
Hypertrophic agonists induce the binding of c-Fos to an AP-1 site in cardiac myocytes: implications for the expression of GLUT1
2003
Objectives: Serum is among the agents known to induce hypertrophy of cardiac myocytes, which occurs concomitant with an increase in AP-1-mediated transcription. We have examined if this effect correlates with changes in the relative abundance of particular AP-1 heterodimers, as their exact composition under these conditions is unknown. Furthermore, we obtained insight on the specific role of c-Fos from studying the induction of the glucose transporter GLUT1 by serum in fibroblasts. Methods: We characterised the AP-1 heterodimers expressed in neonatal cardiac myocytes by supershift electrophoretic mobility shift assay (EMSA) analysis. Quantitative changes in transcription were measured using…
Speckle-based configuration for simultaneous in vitro inspection of mechanical contractions of cardiac myocyte cells.
2013
An optical lensless configuration for a remote noncontact measuring of mechanical contractions of a vast number of cardiac myocytes is proposed. 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 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 (∼1000 cells) and to extra…
FSHD muscular dystrophy region gene 1 binds Suv4-20h1 histone methyltransferase and impairs myogenesis.
2013
Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant myopathy with a strong epigenetic component. It is associated with deletion of a macrosatellite repeat leading to over-expression of the nearby genes. Among them, we focused on FSHD region gene 1 (FRG1) since its over-expression in mice, Xenopus laevis and Caenorhabditis elegans, leads to muscular dystrophy-like defects, suggesting that FRG1 plays a relevant role in muscle biology. Here we show that, when over-expressed, FRG1 binds and interferes with the activity of the histone methyltransferase Suv4-20h1 both in mammals and Drosophila. Accordingly, FRG1 over-expression or Suv4-20h1 knockdown inhibits myogenesis. Moreov…
Autoimmune endocrine ophthalmopathy and retrobulbar antigens.
1995
Endocrine Ophthalmopathy (EO) is based on autoimmune processes that lead to lymphocyte infiltration of the retrobulbar space. In this study, antigenic character of retrobulbar adipose, connective and muscle tissue as well as of cultured fibroblasts and myoblasts were examined. Samples were obtained from EO patients (n = 13, 8 fem., age 26-82 years, median 47 years) undergoing orbital decompression surgery. Retrobulbar and abdominal tissue from 7 controls (4 fem., 48 - 74 y) was investigated, too. Tissues were homogenized and the proteins were separated by SDS-PAGE according to molecular weight. In order to recover the separated proteins in soluble form, an electroelution technique was emplo…