Search results for "Sarcolemma"
showing 10 items of 26 documents
Immune-mediated necrotizing myopathy is characterized by a specific Th1-M1 polarized immune profile.
2012
Immune-mediated necrotizing myopathy (IMNM) is considered one of the idiopathic inflammatory myopathies, comprising dermatomyositis, polymyositis, and inclusion body myositis. The heterogeneous group of necrotizing myopathies shows a varying amount of necrotic muscle fibers, myophagocytosis, and a sparse inflammatory infiltrate. The underlying immune response in necrotizing myopathy has not yet been addressed in detail. Affected muscle tissue, obtained from 16 patients with IMNM, was analyzed compared with eight non-IMNM (nIMNM) tissues. Inflammatory cells were characterized by IHC, and immune mediators were assessed by quantitative real-time PCR. We demonstrate that immune- and non–immune-…
Sarcolemmal excitability as investigated with M-waves after eccentric exercise in humans
2006
It has been shown that intensive eccentric muscle actions lead to prolonged loss of muscle force and sarcolemmal damage. This may lead to a reduction in the excitability of the sarcolemma and contribute to the functional deficit. Experiments were carried out to test sarcolemmal excitability after eccentric elbow flexor exercise in humans. Electrically elicited surface compound muscle action potential (M-wave) properties from 30s stimulation trains (20Hz) were analyzed in biceps brachii muscle immediately after, 1h and 48h after the exercise. M-wave area, amplitude, root mean square and duration were reduced immediately after the eccentric exercise. However, no such reduction could be observ…
Cell Death and Oxidative Damage in Inflammatory Myopathies
1998
There is evidence that muscle fibers in denervating disorders and muscular dystrophies undergo apoptosis. In 21 patients with autoimmune inflammatory myopathies, we found no features of muscle fiber apoptosis such as DNA fragmentation or expression of apoptosis-related proteins. However, muscle fibers in myositis displayed distinct up-regulation of inducible and neuronal nitric oxide synthase (NOS). While inducible NOS was distinctly up-regulated on the sarcolemma of all kinds of muscle fibers neuronal NOS displayed increased expression in the sarcoplasm of damaged as well as atrophic muscle fibers. There were no disease-specific patterns in the different myositis subtypes. Enhanced express…
Dystrophin-deficiency increases the susceptibility to doxorubicin-induced cardiotoxicity
2007
Background and aim: The clinical use of doxorubicin (DOX) and other anthracyclines is limited by a dosage-dependent cardiotoxicity, which can lead to cardiomyopathy. The role of the individual genetic makeup in this disorder is poorly understood. Alterations in genes encoding cardiac cytoskeleton or sarcolemma proteins may increase the susceptibility to doxorubicin-related cardiotoxicity. Methods: Female dystrophin-deficient mice (MDX) and age-matched wild-type mice underwent chronic treatment with doxorubicin. Cardiac function and tissue damage were assessed by echocardiography and histopathology, respectively. Gene expression changes were investigated using microarrays. Results: DOX treat…
Reversible stress-induced lipid body formation in fast twitch rat myofibers
2012
We analyzed the existence of lipid bodies (LBs) in the fast twitch rat flexor digitorum brevis (FDB) myofibers and found that these structures were scarce. However, isolation procedure of the myofibers, heath shock, viral infection or the glycosylation inhibitor tunicamycin induced formation of the LBs, which were stationary structures flanking Z lines. We next infected FDB myofibers with recombinant Semliki Forest virus expressing caveolin 3-yellow fluorescent protein (cav3-YFP) since this chimeric protein was targeted to the LBs facilitating their further analysis. Photobleaching experiments showed that the LBs recovered cav 3-YFP extremely slowly, indicating that they were not continuous…
Protein targeting to the plasma membrane of adult skeletal muscle fiber: an organized mosaic of functional domains.
2001
The plasma membrane of differentiated skeletal muscle fibers comprises the sarcolemma, the transverse (T) tubule network, and the neuromuscular and muscle-tendon junctions. We analyzed the organization of these domains in relation to defined surface markers, beta-dystroglycan, dystrophin, and caveolin-3. These markers were shown to exhibit highly organized arrays along the length of the fiber. Caveolin-3 and beta-dystroglycan/dystrophin showed distinct, but to some extent overlapping, labeling patterns and both markers left transverse tubule openings clear. This labeling pattern revealed microdomains over the entire plasma membrane with the exception of the neuromuscular and muscle-tendon j…
Role of nitric oxide and nitric oxide synthases in experimental models of denervation and reinnervation.
2001
Nitric oxide (NO) is a short-living free molecule synthesized by three different isoforms of nitric oxide synthases (NOS)—neuronal NOS, endothelial NOS, and inducible NOS—associated with neuromuscular transmission, muscle contractility, mitochondrial respiration, and carbohydrate metabolism in skeletal muscle. Neuronal NOS is constitutively expressed at the muscle fiber sarcolemma linked to the dystrophin-glycoprotein complex and concentrated at the neuromuscular endplate. There is increasing evidence that altered expression of neuronal NOS plays a role in muscle fiber damage in neuromuscular diseases such as dystrophinopathies and denervating disorders. Although there have been some previo…
Caveolin 3, flotillin 1 and influenza virus hemagglutinin reside in distinct domains on the sarcolemma of skeletal myofibers.
2011
We examined the distribution of selected raft proteins on the sarcolemma of skeletal myofibers and the role of cholesterol environment in the distribution. Immunofluorescence staining showed that flotillin-1 and influenza hemagglutinin exhibited rafts that located in the domains deficient of the dystrophin glycoprotein complex, but the distribution patterns of the two proteins were different. Cholesterol depletion from the sarcolemma by means of methyl-β-cyclodextrin resulted in distorted caveolar morphology and redistribution of the caveolin 3 protein. Concomitantly, the water permeability of the sarcolemma increased significantly. However, cholesterol depletion did not reshuffle flotillin…
Trans-sarcolemmal proteins situated central to the subsarcolemmal region
2002
Trans-sarcolemmal proteins located inside, within, and outside of the muscle fibre plasma membrane fall into two categories, the dystrophin-glycoprotein complex (DGC) and non-DGC-related proteins, e.g. dysferlin, caveolin, dystrobrevins and syntrophins. Mutational defects are responsible for their immunohistochemical absence or reduction giving rise to certain muscular dystrophies. In other neuromuscular disorders, i.e. inflammatory, metabolic, and neurogenic processes, transarcolemmal proteins are well preserved. Unlike desmin and plectin, which form a honeycomb-type network across the muscle fibre and a subsarcolemmal layer, trans-sarcolemmal proteins are not expressed central to the subs…
Dissociation of theophylline uptake and inotropic effect in myocardial tissue: influence of temperature, pH and calcium.
1975
1. The myocardial uptake and the positive inotropic effect of theophylline (100 mug/ml; 0.56 mM) were studied in isolated electrically driven guinea-pig hearts perfused by the Langendorff technique under various extracellular conditions. [3H]-theophylline was used. 2. Variations in temperature, hydrogen ion and calcium ion concentrations of the perfusion media changed the time course and magnitude of the effect of theophylline on myocardial twitch tension but did not affect the time course and amount of theophylline uptake. 3. Under all conditions, the build-up of the positive inotropic effect of theophylline was about three times faster than the uptake of the drug into the heart. 4. Since …