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Sample records for striated muscle sarcoplasmic

  1. An invertebrate smooth muscle with striated muscle myosin filaments

    PubMed Central

    Sulbarán, Guidenn; Alamo, Lorenzo; Pinto, Antonio; Márquez, Gustavo; Méndez, Franklin; Padrón, Raúl; Craig, Roger

    2015-01-01

    Muscle tissues are classically divided into two major types, depending on the presence or absence of striations. In striated muscles, the actin filaments are anchored at Z-lines and the myosin and actin filaments are in register, whereas in smooth muscles, the actin filaments are attached to dense bodies and the myosin and actin filaments are out of register. The structure of the filaments in smooth muscles is also different from that in striated muscles. Here we have studied the structure of myosin filaments from the smooth muscles of the human parasite Schistosoma mansoni. We find, surprisingly, that they are indistinguishable from those in an arthropod striated muscle. This structural similarity is supported by sequence comparison between the schistosome myosin II heavy chain and known striated muscle myosins. In contrast, the actin filaments of schistosomes are similar to those of smooth muscles, lacking troponin-dependent regulation. We conclude that schistosome muscles are hybrids, containing striated muscle-like myosin filaments and smooth muscle-like actin filaments in a smooth muscle architecture. This surprising finding has broad significance for understanding how muscles are built and how they evolved, and challenges the paradigm that smooth and striated muscles always have distinctly different components. PMID:26443857

  2. Mitsugumin 56 (hedgehog acyltransferase-like) is a sarcoplasmic reticulum-resident protein essential for postnatal muscle maturation.

    PubMed

    Van, Bo; Nishi, Miyuki; Komazaki, Shinji; Ichimura, Atsuhiko; Kakizawa, Sho; Nakanaga, Keita; Aoki, Junken; Park, Ki-Ho; Ma, Jianjie; Ueyama, Tomomi; Ogata, Takehiro; Maruyama, Naoki; Takeshima, Hiroshi

    2015-04-28

    Mitsugumin 56 (MG56), also known as the membrane-bound O-acyl-transferase family member hedgehog acyltransferase-like, was identified as a new sarcoplasmic reticulum component in striated muscle. Mg56-knockout mice grew normally for a week after birth, but shortly thereafter exhibited a suckling defect and died under starvation conditions. In the knockout skeletal muscle, regular contractile features were largely preserved, but sarcoplasmic reticulum elements swelled and further developed enormous vacuoles. In parallel, the unfolded protein response was severely activated in the knockout muscle, and presumably disrupted muscle development leading to the suckling failure. Therefore, MG56 seems essential for postnatal skeletal muscle maturation. PMID:25841338

  3. Independent evolution of striated muscles in cnidarians and bilaterians

    PubMed Central

    Steinmetz, Patrick R.H.; Kraus, Johanna E.M.; Larroux, Claire; U. Hammel, Jörg; Amon-Hassenzahl, Annette; Houliston, Evelyn; Wörheide, Gert; Nickel, Michael; Degnan, Bernard M.; Technau, Ulrich

    2012-01-01

    Striated muscles are present in bilaterian animals (e.g. vertebrates, insects, annelids) and some non-bilaterian eumetazoans (i.e. cnidarians and ctenophores). The striking ultrastructural similarity of striated muscles between these animal groups is thought to reflect a common evolutionary origin1, 2. Here we show that a muscle protein core set, including a Myosin type II Heavy Chain motor protein characteristic of striated muscles in vertebrates (MyHC-st), was already present in unicellular organisms before the origin of multicellular animals. Furthermore, myhc-st and myhc-non-muscle (myhc-nm) orthologues are expressed differentially in two sponges, compatible with the functional diversification of myhc paralogues before the origin of true muscles and the subsequent deployment of MyHC-st in fast-contracting smooth and striated muscle. Cnidarians and ctenophores possess myhc-st orthologues but lack crucial components of bilaterian striated muscles, such as troponin complex and titin genes, suggesting the convergent evolution of striated muscles. Consistently, jellyfish orthologues of a shared set of bilaterian z-disc proteins are not associated with striated muscles, but are instead expressed elsewhere or ubiquitously. The independent evolution of eumetazoan striated muscles through the addition of novel proteins to a pre-existing, ancestral contractile apparatus may serve as a paradigm for the evolution of complex animal cell types. PMID:22763458

  4. Subcellular distribution of potassium in striated muscles

    SciTech Connect

    Edelmann, L.

    1984-01-01

    Microanalytical experiments have been performed to answer the question whether the main cellular cation, K+, follows the water distribution in the striated muscle cell or whether K+ follows the distribution of negative fixed charges (beta- and gamma-carboxyl groups of aspartic and glutamic acid residues). Subcellular localization of K and/or of the K surrogates Rb, Cs, and Tl has been investigated by the following methods: Chemical precipitation of K with tetraphenylborate. Autoradiography of alkali-metals and Tl in air-dried and frozen-hydrated preparations. TEM visualization of electron dense Cs and Tl in sections of freeze-dried and plastic embedded muscle. X-ray microanalysis of air-dried myofibrils and muscle cryosections. The experiments consistently show that K, Rb, Cs, and Tl do not follow the water distribution but are mainly accumulated in the A band, especially in the marginal regions, and at Z lines. The same sites preferentially accumulate Cs or uranyl cations when sections of freeze-dried, embedded muscle are exposed to these electron microscopic stains. It is concluded that the detected uneven distribution of K, Rb, Cs, and Tl in muscle is neither a freeze-drying artifact nor an embedding artifact and may result from a weak ion binding to the beta- and gamma-carboxyl groups of cellular proteins.

  5. Poorly Understood Aspects of Striated Muscle Contraction

    PubMed Central

    Månsson, Alf

    2015-01-01

    Muscle contraction results from cyclic interactions between the contractile proteins myosin and actin, driven by the turnover of adenosine triphosphate (ATP). Despite intense studies, several molecular events in the contraction process are poorly understood, including the relationship between force-generation and phosphate-release in the ATP-turnover. Different aspects of the force-generating transition are reflected in the changes in tension development by muscle cells, myofibrils and single molecules upon changes in temperature, altered phosphate concentration, or length perturbations. It has been notoriously difficult to explain all these events within a given theoretical framework and to unequivocally correlate observed events with the atomic structures of the myosin motor. Other incompletely understood issues include the role of the two heads of myosin II and structural changes in the actin filaments as well as the importance of the three-dimensional order. We here review these issues in relation to controversies regarding basic physiological properties of striated muscle. We also briefly consider actomyosin mutation effects in cardiac and skeletal muscle function and the possibility to treat these defects by drugs. PMID:25961006

  6. Extensive and intensive factors determining the performance of striated muscle.

    PubMed

    Josephson, R K

    1975-10-01

    Striated muscle is obviously a versatile tissue, one which has been malleable to selective pressure and has become modified for many specific tasks. The variations which adapt striated muscle to particular functions involve both changes in its structural organization and changes in the chemical nature of its components. Although a number of factors have been identified which contribute to the diversity of muscle performance, it is not yet possible to account adequately for the wide range in muscle performance throughout the animal kingdom. While not a new direction in comparative physiology, developing quantitative explanations for the diversity of muscle performance is still an obvious, remaining task. PMID:1104752

  7. Neurohypophyseal Hormones: Novel Actors of Striated Muscle Development and Homeostasis

    PubMed Central

    Costa, Alessandra; Rossi, Eleonora; Scicchitano, Bianca Maria; Coletti, Dario; Moresi, Viviana

    2014-01-01

    Since the 1980’s, novel functional roles of the neurohypophyseal hormones vasopressin and oxytocin have emerged. Several studies have investigated the effects of these two neurohormones on striated muscle tissues, both in vitro and in vivo. The effects of vasopressin on skeletal myogenic cells, developing muscle and muscle homeostasis have been documented. Oxytocin appears to have a greater influence on cardiomyocite differentiation and heart homeostasis. This review summarizes the studies on these novel roles of the two neurohypophyseal hormones, and open the possibility of new therapeutic approaches for diseases affecting striated muscle. PMID:26913138

  8. Electromyography of the perineal striated muscles during cystometry.

    PubMed

    Vereecken, R L; Derluyn, J; Verduyn, H

    1975-01-01

    The electromyographic patterns of the external urethral sphincter, the anal sphincter, and the levator ani during cystometries have been analyzed. Synchronized activity changes occur during abdominal straining. Muscle fatigue is very pronounced. Activity may be less synchronized during bladder filling and micturition, even in normal cystometries. In neurogenic diseases, true dyssynergia between the striated muscles may be observed. PMID:1118953

  9. Clinical and Experimental Pancreatic Islet Transplantation to Striated Muscle

    PubMed Central

    Christoffersson, Gustaf; Henriksnäs, Johanna; Johansson, Lars; Rolny, Charlotte; Ahlström, Håkan; Caballero-Corbalan, José; Segersvärd, Ralf; Permert, Johan; Korsgren, Olle; Carlsson, Per-Ola; Phillipson, Mia

    2010-01-01

    OBJECTIVE Curing type 1 diabetes by transplanting pancreatic islets into the liver is associated with poor long-term outcome and graft failure at least partly due to inadequate graft revascularization. The aim of the current study was to evaluate striated muscle as a potential angiogenic site for islet transplantation. RESEARCH DESIGN AND METHODS The current study presents a new experimental model that is found to be applicable to clinical islet transplantation. Islets were implanted into striated muscle and intraislet vascular density and blood flow were visualized with intravital and confocal microscopy in mice and by magnetic resonance imaging in three autotransplanted pancreatectomized patients. Mice were rendered neutropenic by repeated injections of Gr-1 antibody, and diabetes was induced by alloxan treatment. RESULTS Contrary to liver-engrafted islets, islets transplanted to mouse muscle were revascularized with vessel densities and blood flow entirely comparable with those of islets within intact pancreas. Initiation of islet revascularization at the muscular site was dependent on neutrophils, and the function of islets transplanted to muscle was proven by curing diabetic mice. The experimental data were confirmed in autotransplanted patients where higher plasma volumes were measured in islets engrafted in forearm muscle compared with adjacent muscle tissue through high-resolution magnetic resonance imaging. CONCLUSIONS This study presents a novel paradigm in islet transplantation whereby recruited neutrophils are crucial for the functionally restored intraislet blood perfusion following transplantation to striated muscle under experimental and clinical situations. PMID:20651296

  10. Voltage-dependent sodium channels in an invertebrate striated muscle.

    PubMed

    Schwartz, L M; Stühmer, W

    1984-08-01

    Striated skeletal muscles from the planktonic arrowworm Sagitta elegans (phylum Chaetognatha) were voltage-clamped. The muscles displayed classical voltage-dependent sodium channels that (i) showed peak transient currents when the membrane was depolarized 90 millivolts from rest, (ii) opened rapidly with peak currents flowing within 0.4 milliseconds at 4 degrees C, (iii) showed voltage-dependent inactivation with 50 percent inactivation at +25 millivolts from rest, and (iv) were blocked by 500 nanomolar tetrodotoxin. PMID:6330898

  11. Enrichment and terminal differentiation of striated muscle progenitors in vitro

    SciTech Connect

    Becher, Ulrich M.; Breitbach, Martin; Sasse, Philipp; Garbe, Stephan; Ven, Peter F.M. van der; Fuerst, Dieter O.; Fleischmann, Bernd K.

    2009-10-01

    Enrichment and terminal differentiation of mammalian striated muscle cells is severely hampered by fibroblast overgrowth, de-differentiation and/or lack of functional differentiation. Herein we report a new, reproducible and simple method to enrich and terminally differentiate muscle stem cells and progenitors from mice and humans. We show that a single gamma irradiation of muscle cells induces their massive differentiation into structurally and functionally intact myotubes and cardiomyocytes and that these cells can be kept in culture for many weeks. Similar results are also obtained when treating skeletal muscle-derived stem cells and progenitors with Mitomycin C.

  12. Mechanical Stretch-Induced Activation of ROS/RNS Signaling in Striated Muscle

    PubMed Central

    Ward, Christopher W.; Prosser, Benjamin L.

    2014-01-01

    Significance: Mechanical activation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) occurs in striated muscle and affects Ca2+ signaling and contractile function. ROS/RNS signaling is tightly controlled, spatially compartmentalized, and source specific. Recent Advances: Here, we review the evidence that within the contracting myocyte, the trans-membrane protein NADPH oxidase 2 (Nox2) is the primary source of ROS generated during contraction. We also review a newly characterized signaling cascade in cardiac and skeletal muscle in which the microtubule network acts as a mechanotransduction element that activates Nox2-dependent ROS generation during mechanical stretch, a pathway termed X-ROS signaling. Critical Issues: In the heart, X-ROS acts locally and affects the sarcoplasmic reticulum (SR) Ca2+ release channels (ryanodine receptors) and tunes Ca2+ signaling during physiological behavior, but excessive X-ROS can promote Ca2+-dependent arrhythmias in pathology. In skeletal muscle, X-ROS sensitizes Ca2+-permeable sarcolemmal “transient receptor potential” channels, a pathway that is critical for sustaining SR load during repetitive contractions, but when in excess, it is maladaptive in diseases such as Duchenne Musclar dystrophy. Future Directions: New advances in ROS/RNS detection as well as molecular manipulation of signaling pathways will provide critical new mechanistic insights into the details of X-ROS signaling. These efforts will undoubtedly reveal new avenues for therapeutic intervention in the numerous diseases of striated muscle in which altered mechanoactivation of ROS/RNS production has been identified. Antioxid. Redox Signal. 20, 929–936. PMID:23971496

  13. Degree of polarization of light diffracted from resting striated muscle.

    PubMed

    Leung, A F

    1987-04-01

    A laser light diffractometer has been developed to measure directly the total degree of polarization of (alpha t) of light diffracted and randomly scattered from striated muscle fibers. From alpha t the degree of polarization (alpha d) of light diffracted from the periodically arranged contractile filaments is determined. Measurements on single muscle fibers and small fiber bundles indicate that both alpha t and alpha d of the first-order diffraction decrease monotonically with sarcomere length. For the second-order diffraction, alpha t and alpha d exhibit a peak at sarcomere length of about 3.0 micron. A proposed theory based on the anisotropic light scattering efficiencies of the thick and thin filaments can account for the measurements. The comparison between the theory and measurements indicates that the A-band, as well as the I-band, are optically anisotropic. PMID:2443248

  14. Effect of halothane on isometric twitch and tetanus response and the associated heat production in striated muscle of frogs.

    PubMed

    Price, K A; Matsumoto, Y; Frederickson, E L

    1975-01-01

    The purpose of these investigations was to determine the effect of halothane on isometric contraction of striated muscle and to measure the associated heat production. This basic information is necessary before studies more directly relating to malignant hyperthermia are undertaken. Sartorius muscles were isolate from Rana pipiens during winter and summer months. It appears from these experiments that there is a prolongation of the relaxation phase of the twitch and tetanus responses with low concentrations of halothane, with a more diffuse effect on the contractile process evident at higher administered concentrations. The results of heat measurements, using a sensitive thermopile-galvanometer system, are compatible with the hypotheses that this effect on relaxation could result from either an interference with calcium reuptake by the sarcoplasmic reticulum or an increased affinity of the troponintropomyosin complex for available calcium. PMID:1080024

  15. The Chromatin Remodeling Complex Chd4/NuRD Controls Striated Muscle Identity and Metabolic Homeostasis.

    PubMed

    Gómez-Del Arco, Pablo; Perdiguero, Eusebio; Yunes-Leites, Paula Sofia; Acín-Pérez, Rebeca; Zeini, Miriam; Garcia-Gomez, Antonio; Sreenivasan, Krishnamoorthy; Jiménez-Alcázar, Miguel; Segalés, Jessica; López-Maderuelo, Dolores; Ornés, Beatriz; Jiménez-Borreguero, Luis Jesús; D'Amato, Gaetano; Enshell-Seijffers, David; Morgan, Bruce; Georgopoulos, Katia; Islam, Abul B M M K; Braun, Thomas; de la Pompa, José Luis; Kim, Johnny; Enriquez, José A; Ballestar, Esteban; Muñoz-Cánoves, Pura; Redondo, Juan Miguel

    2016-05-10

    Heart muscle maintains blood circulation, while skeletal muscle powers skeletal movement. Despite having similar myofibrilar sarcomeric structures, these striated muscles differentially express specific sarcomere components to meet their distinct contractile requirements. The mechanism responsible is still unclear. We show here that preservation of the identity of the two striated muscle types depends on epigenetic repression of the alternate lineage gene program by the chromatin remodeling complex Chd4/NuRD. Loss of Chd4 in the heart triggers aberrant expression of the skeletal muscle program, causing severe cardiomyopathy and sudden death. Conversely, genetic depletion of Chd4 in skeletal muscle causes inappropriate expression of cardiac genes and myopathy. In both striated tissues, mitochondrial function was also dependent on the Chd4/NuRD complex. We conclude that an epigenetic mechanism controls cardiac and skeletal muscle structural and metabolic identities and that loss of this regulation leads to hybrid striated muscle tissues incompatible with life. PMID:27166947

  16. X-ray Diffraction Studies of Striated Muscles

    SciTech Connect

    Squire, J.M.; Knupp, C.; Roessle, M.; Al-Khayat, H.A.; Irving, T.C.; Eakins, F.; Mok, N.-S.; Harford, J.J.; Reedy, M.K.

    2006-04-24

    In this short review a number of recent X-ray diffraction results on the highly ordered striated muscles in insects and in bony fish have been briefly described. What is clear is that this technique applied to muscles which are amenable to rigorous analysis, taken together with related data from other sources (e.g. protein crystallography, biochemistry, mechanics, computer modelling) can provide not only the best descriptions yet available on the myosin head organisations on different myosin filaments in the relaxed state, but can also show the sequence of molecular events that occurs in the contractile cycle, and may also help to explain such phenomena as stretch-activation. X-ray diffraction is clearly an enormously powerful tool in studies of muscle. It has already provided a wealth of detail on muscle ultrastructure; it is providing ever more fascinating insights into molecular events in the 50-year old sliding filament mechanism, and there remains a great deal more potential that is as yet untapped.

  17. Calcium transport by skeletal muscle sarcoplasmic reticulum in the hypothyroid rat

    PubMed Central

    Fanburg, Barry L.

    1968-01-01

    The rate of calcium transport by isolated sarcoplasmic reticulum from rat skeletal muscle increases markedly during the first 4 wk of life and thereafter remains relatively constant. When animals are made hypothyroid during the first 3 wk of life, there is a marked inhibition of the increase in calcium transport by the sarcoplasmic reticulum. Production of hypothyroidism after 4 wk of age, at which time the calcium transport by sarcoplasmic reticulum has reached maximum levels, results in a depression in the rate of calcium transport. There is no clear alteration in ATPase activity of the sarcoplasmic reticulum to account for the low calcium transport in hypothyroidism. It is proposed that the decrease in calcium transport by sarcoplasmic reticulum may account for observed alterations in the intrinsic contractile properties of muscle in the hypothyroid animal. PMID:4237781

  18. The striated muscles in pulmonary arterial hypertension: adaptations beyond the right ventricle.

    PubMed

    Manders, Emmy; Rain, Silvia; Bogaard, Harm-Jan; Handoko, M Louis; Stienen, Ger J M; Vonk-Noordegraaf, Anton; Ottenheijm, Coen A C; de Man, Frances S

    2015-09-01

    Pulmonary arterial hypertension (PAH) is a fatal lung disease characterised by progressive remodelling of the small pulmonary vessels. The daily-life activities of patients with PAH are severely limited by exertional fatigue and dyspnoea. Typically, these symptoms have been explained by right heart failure. However, an increasing number of studies reveal that the impact of the PAH reaches further than the pulmonary circulation. Striated muscles other than the right ventricle are affected in PAH, such as the left ventricle, the diaphragm and peripheral skeletal muscles. Alterations in these striated muscles are associated with exercise intolerance and reduced quality of life. In this Back to Basics article on striated muscle function in PAH, we provide insight into the pathophysiological mechanisms causing muscle dysfunction in PAH and discuss potential new therapeutic strategies to restore muscle dysfunction. PMID:26113677

  19. Use of flow, electrical, and mechanical stimulation to promote engineering of striated muscles

    PubMed Central

    Rangarajan, Swathi; Madden, Lauran; Bursac, Nenad

    2014-01-01

    The field of tissue engineering involves design of high-fidelity tissue substitutes for predictive experimental assays in vitro and cell-based regenerative therapies in vivo. Design of striated muscle tissues, such as cardiac and skeletal muscle, has been particularly challenging due to a high metabolic demand and complex cellular organization and electromechanical function of the native tissues. Successful engineering of highly functional striated muscles may thus require creation of biomimetic culture conditions involving medium perfusion, electrical and mechanical stimulation. When optimized, these external cues are expected to synergistically and dynamically activate important intracellular signaling pathways leading to accelerated muscle growth and development. This review will discuss the use of different types of tissue culture bioreactors aimed at providing conditions for enhanced structural and functional maturation of engineered striated muscles. PMID:24366526

  20. Embracing change: striated-for-smooth muscle replacement in esophagus development.

    PubMed

    Krauss, Robert S; Chihara, Daisuke; Romer, Anthony I

    2016-01-01

    The esophagus functions to transport food from the oropharyngeal region to the stomach via waves of peristalsis and transient relaxation of the lower esophageal sphincter. The gastrointestinal tract, including the esophagus, is ensheathed by the muscularis externa (ME). However, while the ME of the gastrointestinal tract distal to the esophagus is exclusively smooth muscle, the esophageal ME of many vertebrate species comprises a variable amount of striated muscle. The esophageal ME is initially composed only of smooth muscle, but its developmental maturation involves proximal-to-distal replacement of smooth muscle with striated muscle. This fascinating phenomenon raises two important questions: what is the developmental origin of the striated muscle precursor cells, and what are the cellular and morphogenetic mechanisms underlying the process? Studies addressing these questions have provided controversial answers. In this review, we discuss the development of ideas in this area and recent work that has shed light on these issues. A working model has emerged that should permit deeper understanding of the role of ME development and maturation in esophageal disorders and in the functional and evolutionary underpinnings of the variable degree of esophageal striated myogenesis in vertebrate species. PMID:27504178

  1. Segregation of striated and smooth muscle lineages by a Notch-dependent regulatory network

    PubMed Central

    2014-01-01

    Background Lineage segregation from multipotent epithelia is a central theme in development and in adult stem cell plasticity. Previously, we demonstrated that striated and smooth muscle cells share a common progenitor within their epithelium of origin, the lateral domain of the somite-derived dermomyotome. However, what controls the segregation of these muscle subtypes remains unknown. We use this in vivo bifurcation of fates as an experimental model to uncover the underlying mechanisms of lineage diversification from bipotent progenitors. Results Using the strength of spatio-temporally controlled gene missexpression in avian embryos, we report that Notch harbors distinct pro-smooth muscle activities depending on the duration of the signal; short periods prevent striated muscle development and extended periods, through Snail1, promote cell emigration from the dermomyotome towards a smooth muscle fate. Furthermore, we define a Muscle Regulatory Network, consisting of Id2, Id3, FoxC2 and Snail1, which acts in concert to promote smooth muscle by antagonizing the pro-myogenic activities of Myf5 and Pax7, which induce striated muscle fate. Notch and BMP closely regulate the network and reciprocally reinforce each other’s signal. In turn, components of the network strengthen Notch signaling, while Pax7 silences this signaling. These feedbacks augment the robustness and flexibility of the network regulating muscle subtype segregation. Conclusions Our results demarcate the details of the Muscle Regulatory Network, underlying the segregation of muscle sublineages from the lateral dermomyotome, and exhibit how factors within the network promote the smooth muscle at the expense of the striated muscle fate. This network acts as an exemplar demonstrating how lineage segregation occurs within epithelial primordia by integrating inputs from competing factors. PMID:25015411

  2. The significance of striated muscle in the mammary glands of marsupials.

    PubMed Central

    Griffiths, M; Slater, E

    1988-01-01

    The distribution and amounts of striated muscle within the mammary glands of pouched and pouchless marsupials from Australia and South America are described. Invasions into the mammary secretory parenchyma in pouchless marsupials by swathes of striated muscle from the ilio-marsupialis muscle are massive, in some instances concentrated into discrete muscles, which are inserted on to the bases of the teats; the name retractor mammae is proposed for these muscles. In pouched marsupials striated muscle penetrates the parenchyma, but the distribution is diffuse and the muscle strands are not inserted on to teats except in the instance of the glands of the honey possum Tarsipes rostratus. The young of anaesthetised pouchless marsupials hang down from the teats; as anaesthesia wears off they are hauled up tightly into the mammary area. It is concluded that this is a result of contraction of the retractor mammae muscles and that it is a means of protecting the naked young from injury by rough terrain. The mammary gland musculature in pouched marsupials is considered to be vestigial, but its contraction may have the function of initiating a 'tap-response' contraction of myoepithelium acting synergistically with the 'let-down' hormone mesotocin. Mechanisms of imbibition of milk by marsupial neonates, based on observations that they can suck fluid from non-distortable tubes, are discussed. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 PMID:3417541

  3. Z-line formins promote contractile lattice growth and maintenance in striated muscles of C. elegans

    PubMed Central

    Mi-Mi, Lei; Votra, SarahBeth; Kemphues, Kenneth; Bretscher, Anthony

    2012-01-01

    Muscle contraction depends on interactions between actin and myosin filaments organized into sarcomeres, but the mechanism by which actin filaments incorporate into sarcomeres remains unclear. We have found that, during larval development in Caenorhabditis elegans, two members of the actin-assembling formin family, CYK-1 and FHOD-1, are present in striated body wall muscles near or on sarcomere Z lines, where barbed ends of actin filaments are anchored. Depletion of either formin during this period stunted growth of the striated contractile lattice, whereas their simultaneous reduction profoundly diminished lattice size and number of striations per muscle cell. CYK-1 persisted at Z lines in adulthood, and its near complete depletion from adults triggered phenotypes ranging from partial loss of Z line–associated filamentous actin to collapse of the contractile lattice. These results are, to our knowledge, the first genetic evidence implicating sarcomere-associated formins in the in vivo organization of the muscle cytoskeleton. PMID:22753896

  4. Effects of boldine on mouse diaphragm and sarcoplasmic reticulum vesicles isolated from skeletal muscle.

    PubMed

    Kang, J J; Cheng, Y W

    1998-02-01

    The effects of boldine [(S)-2,9-dihydroxy-1,10-dimethoxyaporphine], a major alkaloid in the leaves and bark of boldo (Peumus boldus Mol.), on skeletal muscle were studied using mouse diaphragm and isolated sarcoplasmic reticulum membrane vesicles. Boldine, at 10-200 microM, has little effect on the muscle-evoked twitches; however, the ryanodine-induced contracture was potentiated dose-dependently. At higher concentrations of 300 microM, boldine by itself induced muscle contracture of two phases, which were caused by the influx of extracellular Ca2+ and induction of Ca2+ release from the internal Ca2+ storage site, the sarcoplasmic reticulum, respectively. When tested with isolated sarcoplasmic reticulum membrane vesicles, boldine dose-dependently induced Ca2+ release from actively loaded sarcoplasmic reticulum vesicles isolated from skeletal muscle of rabbit or rat which was inhibited by ruthenium red, suggesting that the release was through the Ca2+ release channel, also known as the ryanodine receptor. Boldine also dose-dependently increased apparent [3H]-ryanodine binding with the EC50 value of 50 microM. In conclusion, we have shown that boldine could sensitize the ryanodine receptor and induce Ca2+ release from the internal Ca2+ storage site of skeletal muscle. PMID:9491763

  5. Rapid cooling-induced contractures in rat skinned skeletal muscle fibres originate from sarcoplasmic reticulum Ca2+ release through ryanodine and inositol trisphosphate receptors.

    PubMed

    Talon, S; Huchet-Cadiou, C; Léoty, C

    2000-11-01

    Previous reports have shown that cooling striated muscles induces contractile responses that are related to Ca2+ release from the sarcoplasmic reticulum. However, the effect of cooling has generally been studied in the presence of pharmacological agents that potentiate rapid cooling-induced contractures. The present study shows that in saponin-skinned rat skeletal muscle preparations, a drop in temperature from 22 degrees C to 2 degrees C per se induces a contracture which relaxes on return to 22 degrees C. In fast-twitch fibres, rapid cooling-induced contractures are fully blocked by ryanodine, an inhibitor of ryanodine receptors. By contrast, in slow-twitch fibres, ryanodine partially inhibits the rapid cooling-induced contractile response, leaving a residual tension that dissipates after application of inositol 1,4,5-trisphosphate (InsP3). At low concentrations, heparin, an inhibitor of InsP3 receptors, decreases rapid cooling-induced contractures in both types of muscle. The present results suggest that in skeletal muscle, rapid cooling-induced contractures are due to both ryanodine-sensitive and InsP3-sensitive Ca2+ release from the sarcoplasmic reticulum. PMID:11205048

  6. Porcine malignant hyperthermia susceptibility: increased calcium-sequestering activity of skeletal muscle sarcoplasmic reticulum.

    PubMed Central

    O'Brien, P J

    1986-01-01

    This study tested the hypothesis that calcium-sequestration by isolated sarcoplasmic reticulum was abnormal in skeletal muscle of malignant hyperthermia-susceptible swine. A heavy sarcoplasmic reticulum fraction was isolated from malignant hyperthermia and control muscle using differential and density-gradient centrifugation. Prior to onset of malignant hyperthermia, calcium-sequestering activity (Vmax at 37 degrees C, mumol calcium/mg/min) was twofold increased in malignant hyperthermia sarcoplasmic reticulum compared to control sarcoplasmic reticulum (1.96 +/- 0.50 versus 4.00 +/- 0.87, P less than 0.01), although thermodynamic and kinetic properties of this activity were otherwise indistinguishable between groups. This increased activity of the malignant hyperthermia sarcoplasmic reticulum fraction was associated with twofold increased concentration of Ca-ATPase and calsequestrin protein. When a malignant hyperthermia-reaction developed, calcium-uptake was depressed to less than 5% of control values. These data indicate that malignant hyperthermia is not initiated due to a defect in the calcium-sequestration mechanism, however, loss of calcium-uptake activity occurring after the onset of malignant hyperthermia might result in the propagation and irreversibility of the malignant hyperthermia reaction. Images Fig. 1. PMID:3742368

  7. A Calsequestrin-1 Mutation Associated with a Skeletal Muscle Disease Alters Sarcoplasmic Ca2+ Release

    PubMed Central

    D’Adamo, Maria Cristina; Sforna, Luigi; Visentin, Sergio; Grottesi, Alessandro; Servettini, llenio; Guglielmi, Luca; Macchioni, Lara; Saredi, Simona; Curcio, Maurizio; De Nuccio, Chiara; Hasan, Sonia; Corazzi, Lanfranco; Franciolini, Fabio; Mora, Marina; Catacuzzeno, Luigi; Pessia, Mauro

    2016-01-01

    An autosomal dominant protein aggregate myopathy, characterized by high plasma creatine kinase and calsequestrin-1 (CASQ1) accumulation in skeletal muscle, has been recently associated with a missense mutation in CASQ1 gene. The mutation replaces an evolutionarily-conserved aspartic acid with glycine at position 244 (p.D244G) of CASQ1, the main sarcoplasmic reticulum (SR) Ca2+ binding and storage protein localized at the terminal cisternae of skeletal muscle cells. Here, immunocytochemical analysis of myotubes, differentiated from muscle-derived primary myoblasts, shows that sarcoplasmic vacuolar aggregations positive for CASQ1 are significantly larger in CASQ1-mutated cells than control cells. A strong co-immuno staining of both RyR1 and CASQ1 was also noted in the vacuoles of myotubes and muscle biopsies derived from patients. Electrophysiological recordings and sarcoplasmic Ca2+ measurements provide evidence for less Ca2+ release from the SR of mutated myotubes when compared to that of controls. These findings further clarify the pathogenic nature of the p.D244G variant and point out defects in sarcoplasmic Ca2+ homeostasis as a mechanism underlying this human disease, which could be distinctly classified as “CASQ1-couplonopathy”. PMID:27196359

  8. Modulation of the cytosolic androgen receptor in striated muscle by sex steroids

    NASA Technical Reports Server (NTRS)

    Rance, N. E.; Max, S. E.

    1982-01-01

    The influence of orchiectomy (GDX) and steroid administration on the level of the cytosolic androgen receptor in the rat levator ani muscle and in rat skeletal muscles (tibialis anterior and extensor digitorum longus) was studied. Androgen receptor binding to muscle cytosol was measured using H-3 methyltrienolone (R1881) as ligand, 100 fold molar excess unlabeled R1881 to assess nonspecific binding, and 500 fold molar excess of triamcinolone acetonide to prevent binding to glucocorticoid and progestin receptors. Results demonstrate that modification of the levels of sex steroids can alter the content of androgen receptors of rat striated muscle. Data suggest that: (1) cytosolic androgen receptor levels increase after orchiectomy in both levator ani muscle and skeletal muscle; (2) the acute increase in receptor levels is blocked by an inhibitor of protein synthesis; and (3) administration of estradiol-17 beta to castrated animals increases receptor binding in levator ani muscle but not in skeletal muscle.

  9. The regulation and function of the striated muscle activator of rho signaling (STARS) protein

    PubMed Central

    Wallace, Marita A.; Lamon, Séverine; Russell, Aaron P.

    2012-01-01

    Healthy living throughout the lifespan requires continual growth and repair of cardiac, smooth, and skeletal muscle. To effectively maintain these processes muscle cells detect extracellular stress signals and efficiently transmit them to activate appropriate intracellular transcriptional programs. The striated muscle activator of Rho signaling (STARS) protein, also known as Myocyte Stress-1 (MS1) protein and Actin-binding Rho-activating protein (ABRA) is highly enriched in cardiac, skeletal, and smooth muscle. STARS binds actin, co-localizes to the sarcomere and is able to stabilize the actin cytoskeleton. By regulating actin polymerization, STARS also controls an intracellular signaling cascade that stimulates the serum response factor (SRF) transcriptional pathway; a pathway controlling genes involved in muscle cell proliferation, differentiation, and growth. Understanding the activation, transcriptional control and biological roles of STARS in cardiac, smooth, and skeletal muscle, will improve our understanding of physiological and pathophysiological muscle development and function. PMID:23248604

  10. Electron microscopical and histochemical studies on the transverse striated muscles of birds after prolonged hypokinesis

    NASA Technical Reports Server (NTRS)

    Belak, M.; Kocisova, J.; Marcanik, J.; Boda, K.; Skarda, R.

    1981-01-01

    Studies of the gastrocnemius muscle were carried out in 4 month old cockerels of the laying hybrid after hypokinesis lasting 15 and 30 days. It was found that restricted movement resulted in dystrophic changes of myotibrils, enlargement of the sarcoplasmic reticulum and oedem of interfibrillar spaces. Histochemical studies revealed focuses of increased activity of non-specific esterase, decreased activity of dehydrogenase of lactic acid and a positive reaction of acid phosphatase.

  11. Striated muscle involvement in experimental oral infection by herpes simplex virus type 1.

    PubMed

    Gonzalez, María Inés; Sanjuan, Norberto A

    2013-07-01

    Herpes simplex virus type 1 is one of the most frequent causes of oral infection in humans, especially during early childhood. Several experimental models have been developed to study the pathogenesis of this virus but all of them employed adult animals. In this work, we developed an experimental model that uses mice younger than 4 days old, to more closely resemble human infection. Mice were infected subcutaneously with the prototype strain McIntyre of Herpes simplex-1, and the progression of infection was studied by immunoperoxidase. All animals died within 24-72 h post-infection, while viral antigens were found in the oral epithelium, nerves and brain. The most striking result was the finding of viral antigens in the nucleus and cytoplasm of cells belonging to striated muscles. Organotypic cultures of striated muscles were performed, and viral replication was observed in them by immunocytochemistry, electron microscopy and viral isolation. We conclude that the infection of striated muscles is present from the onset of oral infection and, eventually, could explain some clinical observations in humans. PMID:23445118

  12. Myocardium and striated muscle damage caused by licit or illicit drugs.

    PubMed

    Tóth, Anita Réka; Varga, Tibor

    2009-04-01

    Illicit and central nervous system active licit drug consumption related deaths are mainly the consequences of either unintentional or intentional overdose. According to the data in the relevant literature occurrences of different organ damages are also observable and this can play a role in death, as well. Organ damages may appear simultaneously with overdosing or can be extended in time, which may lead to proving the cause of death and establishing the relationships with previous medication difficult. The most frequent damage observed is rhabdomyolysis syndrome, which has been mainly described after cocaine or opium consumption. Authors present four cases from the autopsy documentation of the period between 2003 and 2008 at the Institute of Forensic Medicine, University of Szeged, Hungary in which illicit drug consumption or neuroleptic licit drug medication resulted in development of myocardium and striated muscle damage. The dominant clinical symptoms were hyperthermia, renal and circulatory failure. The laboratory tests showed renal and liver insufficiency; in addition the CK and CK-MB level increase suggested damage in striated muscles. The focal myocardium and striated muscle damage could be assessed as the cause of death in one case, but microscopic investigation proved the presence of damage in each. PMID:19342269

  13. Systemic delivery of genes to striated muscles using adeno-associated viral vectors.

    PubMed

    Gregorevic, Paul; Blankinship, Michael J; Allen, James M; Crawford, Robert W; Meuse, Leonard; Miller, Daniel G; Russell, David W; Chamberlain, Jeffrey S

    2004-08-01

    A major obstacle limiting gene therapy for diseases of the heart and skeletal muscles is an inability to deliver genes systemically to muscles of an adult organism. Systemic gene transfer to striated muscles is hampered by the vascular endothelium, which represents a barrier to distribution of vectors via the circulation. Here we show the first evidence of widespread transduction of both cardiac and skeletal muscles in an adult mammal, after a single intravenous administration of recombinant adeno-associated virus pseudotype 6 vectors. The inclusion of vascular endothelium growth factor/vascular permeability factor, to achieve acute permeabilization of the peripheral microvasculature, enhanced tissue transduction at lower vector doses. This technique enabled widespread muscle-specific expression of a functional micro-dystrophin in the skeletal muscles of dystrophin-deficient mdx mice, which model Duchenne muscular dystrophy. We propose that these methods may be applicable for systemic delivery of a wide variety of genes to the striated muscles of adult mammals. PMID:15273747

  14. Molecular transformations in sarcoplasmic reticulum of fast-twitch muscle by electro-stimulation.

    PubMed

    Heilmann, C; Pette, D

    1979-02-01

    Chronic electro-stimulation of fast-twitch rabbit muscle with the frequency pattern received by a slow-twitch muscle induces a progressive transformation of the sarcoplasmic reticulum. After 2 days stimulation activities of Ca2+-dependent ATPase and of Ca2+ transport begin to decrease, and are paralleled by a progressive decrease in Ca2+-dependent and Ca2+, Mg2+-dependent phosphoprotein formation, reduced rate of dephosphorylation and a rearrangement of the electrophoretic polypeptide and phosphoprotein patterns. These findings suggest a transformation of the sarcoplasmic reticulum to resemble that of a slow-twitch muscle. This transformation is paralleled by increase in time-to-peak of twitch contraction and half relaxation time and occurs before conversion of the myosin light chain pattern is observed. The parallel time course of changes in contractile properties of stimulated muscle and the molecular and functional properties of the sarcoplasmic reticulum emphasizes the definitive role of the latter in determining the twitch characteristics of fast and slow twitch muscles. PMID:154404

  15. Perineal striated muscles: Anatomy, spinal motoneurons, and participation on copulatory behavior in male rabbits (Oryctolagus cuniculus).

    PubMed

    Zempoalteca, R; Lucio, R A; Eguibar, J R

    2008-09-01

    Despite the importance of rabbits in reproductive studies, little information is available on the anatomy and participation of the striated-perineal muscles in male copulatory behavior. In our study, we describe the gross anatomy of two striated-perineal muscles: the ischiocavernosus (ICm) and the bulbospongiosus (BSm). Both muscles have their origin at the ischiadic arc, but the ICm is inserted into the penile crura and the BSm onto the ligamentum suspensorium of the penis. The motoneurons of both muscles were identified using retrograde labeling with horseradish peroxidase coupled to wheat-germ agglutinin. Motoneurons were dispersed in the lower-lumbar and upper-sacral spinal-cord segments, instead of being aggregated in the neuronal nucleus as in other species: the rat, mouse, gerbil, cat, and man. Bilateral dennervation of the ICm or BSm or both in sexually experienced male rabbits did not affect copulatory variables measured at 10, 20, and 30 days after surgery. However, muscular dennervation produced extravaginal ejaculations in 42% of copulatory tests and no ejaculation in 7% of tests, although male pelvic thrusting occurred. These results suggest the participation of the ICm and BSm perineal muscles in penile orientation during copulation but not in seminal emission as described in other mammalian species. PMID:18563835

  16. Striated Muscle as Implantation Site for Transplanted Pancreatic Islets

    PubMed Central

    Espes, Daniel; Eriksson, Olof; Lau, Joey; Carlsson, Per-Ola

    2011-01-01

    Islet transplantation is an attractive treatment for selected patients with brittle type 1 diabetes. In the clinical setting, intraportal transplantation predominates. However, due to extensive early islet cell death, the quantity of islets needed to restore glucose homeostasis requires in general a minimum of two donors. Moreover, the deterioration of islet function over time results in few insulin-independent patients after five-year followup. Specific obstacles to the success of islet transplantation include site-specific concerns for the liver such as the instant blood mediated inflammatory reaction, islet lipotoxicity, low oxygen tension, and poor revascularization, impediments that have led to the developing interest for alternative implantation sites over recent years. Within preclinical settings, several alternative sites have now been investigated and proven favorable in various aspects. Muscle is considered a very promising site and has physiologically properties and technical advantages that could make it optimal for islet transplantation. PMID:22174984

  17. Sarcoplasmic reticulum function and muscle contractile character following fatiguing exercise in humans

    PubMed Central

    Hill, Christopher A; Thompson, Martin W; Ruell, Patricia A; Thom, Jeanette M; White, Michael J

    2001-01-01

    This study examined the alterations in calcium release, calcium uptake and calcium ATPase activity of skeletal muscle sarcoplasmic reticulum in response to a bout of intense dynamic knee extensor exercise, and the relationship between these changes and alterations in muscle contractile characteristics in the human quadriceps. In biopsy samples taken from the vastus lateralis, sarcoplasmic reticulum calcium release and calcium uptake were significantly depressed (P < 0.01 and 0.05, respectively) immediately following the exercise with no alteration in the sarcoplasmic reticulum Ca2+-ATPase activity. A 33 % reduction in the maximum voluntary isometric torque was found following the exercise, with reduced torques from electrically evoked isometric contractions at low frequencies of stimulation (10 and 20 Hz) but not at higher frequencies (50 and 100 Hz). The depressed calcium release was correlated (P < 0.05) with a decreased ratio of torques generated at 20:50 Hz, indicating an involvement in low frequency fatigue; however, no correlations between the muscle relaxation times or rates of change of torque and calcium uptake were observed. PMID:11251066

  18. Frog striated muscle is permeable to hydroxide and buffer anions.

    PubMed

    Venosa, R A; Kotsias, B A; Horowicz, P

    1994-04-01

    Hydroxide, bicarbonate and buffer anion permeabilities in semitendinosus muscle fibers of Rana pipiens were measured. In all experiments, the fibers were initially equilibrated in isotonic, high K2SO4 solutions at pHo = 7.2 buffered with phosphate. Two different methods were used to estimate permeabilities: (i) membrane potential changes were recorded in response to changes in external ion concentrations, and (ii) intracellular pH changes were recorded in response to changes in external concentrations of ions that alter intracellular pH. Constant field equations were used to calculate relative or absolute permeabilities. In the first method, to increase the size of the membrane potential change produced by a sudden change in anion entry, external K+ was replaced by Cs+ prior to changes of the anion under study. At constant external Cs+ activity, a hyperpolarization results from increasing external pH from 7.2 to 10.0 or higher, using either CAPS (3-[cyclohexylamino]-1-propanesulfonic acid) or CHES (2-[N-cyclohexylamino]-ethanesulfonic acid) as buffer. For each buffer, the protonated form is a zwitterion of zero net charge and the nonprotonated form is an anion. Using reported values of H+ permeability, calculations show that the reduction in [H+]o cannot account for the hyperpolarizations produced by alkaline solutions. Membrane hyperpolarization increases with increasing total external buffer concentration at constant external pH, and with increasing external pH at constant external buffer anion concentration. Taken together, these observations indicate that both OH- and buffer anions permeate the surface membrane. The following relative permeabilities were obtained at pHo = 10.0 +/- 0.3: (POH/PK) = 890 +/- 150, (PCAPS/PK) = 12 +/- 2, (PCHES/PK) = 5.3 +/- 0.9, and (PNO3/PK) = 4.7 +/- 0.5. PNO3/PK was independent of pHo up to 10.75. At pHo = 9.6, (PHCO3/PK) = 0.49 +/- 0.03; at pHo = 8.9, (PCl/PK) = 18 +/- 2 and at pHo = 7.1, (PHEPES/PK) = 20 +/- 2. In the second

  19. Ultrastructural studies of the mitochondriae in the striated muscles of birds with regard to experimental hypokinesis

    NASA Technical Reports Server (NTRS)

    Belak, M.; Kocisova, J.; Boda, K.

    1980-01-01

    Electron microscopic studies were carried out on the mitochrondria of the transversely striated muscles with regard to experimental hypokinesia. As compared to the central group the mitochondria of m. pectoralis thoracicus and the m. iliotibialis posterior in hypokinetic birds reveal marked changes. In filamentous and ovoid mitochondria, vacuoles can be observed which in some cases produced larger light formations with following disappearance of the cristae and destruction of mitochondria. Fat particles located at the poles of the altered mitochondria, sporadically occurring also laterally, presented another finding. The Z-lines of the sarcomere did not form a continuous line, but were somewhat shifted.

  20. The Popeye Domain Containing Genes and their Function in Striated Muscle

    PubMed Central

    Schindler, Roland FR; Scotton, Chiara; French, Vanessa; Ferlini, Alessandra; Brand, Thomas

    2016-01-01

    The Popeye domain containing (POPDC) genes encode a novel class of cAMP effector proteins, which are abundantly expressed in heart and skeletal muscle. Here we will review their role in striated muscle as deduced from work in cell and animal models and the recent analysis of patients carrying a missense mutation in POPDC1. Evidence suggests that POPDC proteins control membrane trafficking of interacting proteins. Furthermore, we will discuss the current catalogue of established protein-protein interactions. In recent years, the number of POPDC-interacting proteins is rising and currently includes ion channels (TREK-1), sarcolemma-associated proteins serving functions in mechanical stability (Dystrophin), compartmentalization (Caveolin 3), scaffolding (ZO-1), trafficking (NDRG4, VAMP2/3) and repair (Dysferlin), or acting as a guanine nucleotide exchange factor for Rho-family GTPases (GEFT). Recent evidence suggests that POPDC proteins might also control the cellular level of the nuclear proto-oncoprotein c-Myc. These data suggests that this family of cAMP-binding proteins probably serves multiple roles in striated muscle. PMID:27347491

  1. Isoform composition, gene expression and sarcomeric protein phosphorylation in striated muscle of mice after space flight

    NASA Astrophysics Data System (ADS)

    Vikhlyantsev, Ivan; Ulanova, Anna; Salmov, Nikolay; Gritsyna, Yulia; Bobylev, Alexandr; Rogachevsky, Vadim; Shenkman, Boris; Podlubnaya, Zoya

    Using RT-PCR and SDS-PAGE, changes in isoform composition, gene expression, titin and nebulin phosphorylation, as well as changes in isoform composition of myosin heavy chains in striated muscles of mice were studied after 30-day-long space flight onboard the Russian spacecraft “BION-M” No. 1. The muscle fibre-type shift from slow-to-fast was observed in m. gastrocnemius and m. tibialis anterior of animals from “Flight” group. A decrease in the content of the NT and N2A titin isoforms and nebulin in the skeletal muscles of animals from “Flight” group was found. Meanwhile, significant differences in gene expression of these proteins in skeletal muscles of mice from “Flight” and “Control” groups were not observed. Using Pro-Q Diamond stain, an increase in titin phosphorylation in m. gastrocnemius of mice from “Flight” group was detected. The content of the NT, N2BA and N2B titin isoforms in cardiac muscle of mice from “Flight” and “Control” groups did not differ, nevertheless an increase in titin gene expression in the myocardium of the “Flight” group animals was found. The observed changes will be discussed in the context of theirs role in contractile activity of striated muscles of mice in conditions of weightlessness. This work was supported by the Russian Foundation for Basic Research (grants No. 14-04-32240, 14-04-00112). Acknowledgement. We express our gratitude to the teams of Institute of Biomedical Problems RAS and “PROGRESS” Corporation involved in the preparation of the “BION-M” mission.

  2. Regulation of structure and function of sarcomeric actin filaments in striated muscle of the nematode Caenorhabditis elegans

    PubMed Central

    Ono, Shoichiro

    2014-01-01

    The nematode Caenorhabditis elegans has been used as a valuable system to study structure and function of striated muscle. The body wall muscle of C. elegans is obliquely striated muscle with highly organized sarcomeric assembly of actin, myosin, and other accessary proteins. Genetic and molecular biological studies in C. elegans have identified a number of genes encoding structural and regulatory components for the muscle contractile apparatuses, and many of them have counterparts in mammalian cardiac and skeletal muscles or striated muscles in other invertebrates. Applicability of genetics, cell biology, and biochemistry has made C. elegans an excellent system to study mechanisms of muscle contractility and assembly and maintenance of myofibrils. This review focuses on the regulatory mechanisms of structure and function of actin filaments in the C. elegans body wall muscle. Sarcomeric actin filaments in C. elegans muscle are associated with the troponin-tropomyosin system that regulates the actin-myosin interaction. Proteins that bind to the side and ends of actin filaments support ordered assembly of thin filaments. Furthermore, regulators of actin dynamics play important roles in initial assembly, growth, and maintenance of sarcomeres. The knowledge acquired in C. elegans can serve as bases to understand the basic mechanisms of muscle structure and function. PMID:25125169

  3. Quantitative determination of Ca2+-dependent Mg2+-ATPase from sarcoplasmic reticulum in muscle biopsies.

    PubMed Central

    Everts, M E; Andersen, J P; Clausen, T; Hansen, O

    1989-01-01

    The possibility of quantifying the total concentration of Ca2+-dependent Mg2+-ATPase of sarcoplasmic reticulum was investigated by measurement of the Ca2+-dependent steady-state phosphorylation from [gamma-32P]ATP and the Ca2+-dependent 3-O-methylfluorescein phosphatase (3-O-MFPase) activity in crude muscle homogenates. The Ca2+-dependent phosphorylation at 0 degree C (mean +/- S.E.) was 40.0 +/- 2.5 (n = 6) and 6.2 +/- 0.7 (n = 4) nmol/g wet wt. in rat extensor digitorum longus (EDL) and soleus muscle, respectively (P less than 0.001). The Ca2+-dependent 3-O-MFPase activity at 37 degrees C was 1424 +/- 238 (n = 6) and 335 +/- 56 (n = 4) nmol/min per g wet wt. in rat EDL and soleus muscle, respectively (P less than 0.01). The molecular activity calculated from these measurements amounted to 35 +/- 5 min-1 (n = 6) and 55 +/- 10 min-1 (n = 4) for EDL and soleus muscle respectively. These values were not different from the molecular activity calculated for purified Ca2+-ATPase (36 min-1). The Ca2+-dependent 32P incorporation in soleus muscle decreased in the order mice greater than rats greater than guinea pigs. In EDL muscles from hypothyroid rats at a 30% reduction of the Ca2+-dependent phosphorylation was observed. The Ca2+-dependent phosphorylation in vastus lateralis muscle from three human subjects amounted to 4.5 +/- 0.8 nmol/g wet wt. It is concluded that measurement of the Ca2+-dependent phosphorylation allows rapid and reproducible quantification of the concentration of Ca2+-dependent Mg2+-ATPase of sarcoplasmic reticulum. Since only 20-60 mg of tissue is required for the measurements, the method can also be used for biopsies obtained in clinical studies. PMID:2548478

  4. Pharmacological modulation of sarcoplasmic reticulum function in smooth muscle.

    PubMed

    Laporte, Régent; Hui, Adrian; Laher, Ismail

    2004-12-01

    The sarco/endoplasmic reticulum (SR/ER) is the primary storage and release site of intracellular calcium (Ca2+) in many excitable cells. The SR is a tubular network, which in smooth muscle (SM) cells distributes close to cellular periphery (superficial SR) and in deeper aspects of the cell (deep SR). Recent attention has focused on the regulation of cell function by the superficial SR, which can act as a buffer and also as a regulator of membrane channels and transporters. Ca2+ is released from the SR via two types of ionic channels [ryanodine- and inositol 1,4,5-trisphosphate-gated], whereas accumulation from thecytoplasm occurs exclusively by an energy-dependent sarco-endoplasmic reticulum Ca2+-ATPase pump (SERCA). Within the SR, Ca2+ is bound to various storage proteins. Emerging evidence also suggests that the perinuclear portion of the SR may play an important role in nuclear transcription. In this review, we detail the pharmacology of agents that alter the functions of Ca2+ release channels and of SERCA. We describe their use and selectivity and indicate the concentrations used in investigating various SM preparations. Important aspects of cell regulation and excitation-contractile activity coupling in SM have been uncovered through the use of such activators and inhibitors of processes that determine SR function. Likewise, they were instrumental in the recent finding of an interaction of the SR with other cellular organelles such as mitochondria. Thus, an appreciation of the pharmacology and selectivity of agents that interfere with SR function in SM has greatly assisted in unveiling the multifaceted nature of the SR. PMID:15602008

  5. Characteristics of sarcoplasmic reticulum from slowly glycolysing and from rapidly glycolysing pig skeletal muscle post mortem

    PubMed Central

    McIntosh, David B.; Berman, Mervyn C.; Kench, James E.

    1977-01-01

    The composition and function of fragmented sarcoplasmic reticulum from pig skeletal muscle was examined in the period immediately post mortem. Muscle was defined as being either slowly glycolysing or rapidly glycolysing on the basis of colour, pH and concentrations of glycogen and lactate. The microsomal fraction was separated on a discontinuous gradient of 35, 40 and 45% (w/v) sucrose into heavy and intermediate fractions which sedimented to the interfaces, and a light fraction which remained on the surface of the 35%-sucrose layer. The sarcoplasmic reticulum from rapidly glycolysing muscle had a lower buoyant density than had that from slowly glycolysing muscle. This was reflected in the consistent lack of material in the heavy fraction and a greater proportion in the light fraction. The latter material had significantly lower ratios (w/w) of protein to phospholipid (2.3:1 versus 3.8:1) and of protein to cholesterol (10.4:1 versus 15.6:1). There were no gross differences in phospholipid content or in fatty acid composition of individual phospholipid classes in the membranes from the two types of muscle. Analysis of membrane proteins by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis showed that ATPase (adenosine triphosphatase) was a major component of each fraction and that its contribution to the total protein content of the membrane was greater in rapidly glycolysing muscle, suggesting a loss of non-ATPase proteins. The two fractions of sarcoplasmic reticulum prepared from rapidly glycolysing muscle had approximately one-third the normal activities of Ca2+ binding and Ca2+ uptake in the presence of ATP and one-half the passive Ca2+-binding capacity in the absence of ATP of the fractions from slowly glycolysing muscle. However, the (Ca2++Mg2+)-stimulated ATPase activities were similar. Efflux from actively loaded vesicles, after the addition of EDTA, consisted of a rapid and a slow phase. Vesicles from rapidly glycolysing muscle lost 60% of

  6. Overexpression of Striated Muscle Activator of Rho Signaling (STARS) Increases C2C12 Skeletal Muscle Cell Differentiation

    PubMed Central

    Wallace, Marita A.; Della Gatta, Paul A.; Ahmad Mir, Bilal; Kowalski, Greg M.; Kloehn, Joachim; McConville, Malcom J.; Russell, Aaron P.; Lamon, Séverine

    2016-01-01

    Background: Skeletal muscle growth and regeneration depend on the activation of satellite cells, which leads to myocyte proliferation, differentiation and fusion with existing muscle fibers. Skeletal muscle cell proliferation and differentiation are tightly coordinated by a continuum of molecular signaling pathways. The striated muscle activator of Rho signaling (STARS) is an actin binding protein that regulates the transcription of genes involved in muscle cell growth, structure and function via the stimulation of actin polymerization and activation of serum-response factor (SRF) signaling. STARS mediates cell proliferation in smooth and cardiac muscle models; however, whether STARS overexpression enhances cell proliferation and differentiation has not been investigated in skeletal muscle cells. Results: We demonstrate for the first time that STARS overexpression enhances differentiation but not proliferation in C2C12 mouse skeletal muscle cells. Increased differentiation was associated with an increase in the gene levels of the myogenic differentiation markers Ckm, Ckmt2 and Myh4, the differentiation factor Igf2 and the myogenic regulatory factors (MRFs) Myf5 and Myf6. Exposing C2C12 cells to CCG-1423, a pharmacological inhibitor of SRF preventing the nuclear translocation of its co-factor MRTF-A, had no effect on myotube differentiation rate, suggesting that STARS regulates differentiation via a MRTF-A independent mechanism. Conclusion: These findings position STARS as an important regulator of skeletal muscle growth and regeneration. PMID:26903873

  7. Expression of sarcoplasmic reticulum Ca(2+)-ATPase isoforms in marlin and swordfish muscle and heater cells.

    PubMed

    Tullis, A; Block, B A

    1996-07-01

    The superior rectus muscles of marlin, swordfish, sailfish, and spearfish are modified for generating heat rather than force. This study focuses on the sarcoplasmic reticulum calcium-adenosinetriphosphatase (SR Ca(2+)-ATPase) to gain further insight into the muscle fiber type origin of the billfish "heater cell." Direct sequencing and immunolocalization demonstrated that marlin and swordfish epaxial swimming muscles express two forms of the SR Ca(2+)-ATPase in a fiber type-specific manner; red slow-twitch skeletal and cardiac muscles express the same SERCA2 message, whereas white fast-twitch skeletal muscles express a SERCA1 message. Thus the expression pattern of the SR Ca2+ pump is similar in both billfish and tetrapod muscles. Molecular and immunological studies revealed that billfish heater tissue and superior rectus muscle express both fast and slow SR Ca2+ pump isoforms. Immunohistochemical results suggest that heater cells and most extraocular muscle fibers express the fast SR Ca2+ pump. Expression of the fast SR Ca(2+)-ATPase by heater cells has implications for heater cell origin and thermogenic control. PMID:8760229

  8. Revealing T-Tubules in Striated Muscle with New Optical Super-Resolution Microscopy Techniquess.

    PubMed

    Jayasinghe, Isuru D; Clowsley, Alexander H; Munro, Michelle; Hou, Yufeng; Crossman, David J; Soeller, Christian

    2015-01-01

    The t-tubular system plays a central role in the synchronisation of calcium signalling and excitation-contraction coupling in most striated muscle cells. Light microscopy has been used for imaging t-tubules for well over 100 years and together with electron microscopy (EM), has revealed the three-dimensional complexities of the t-system topology within cardiomyocytes and skeletal muscle fibres from a range of species. The emerging super-resolution single molecule localisation microscopy (SMLM) techniques are offering a near 10-fold improvement over the resolution of conventional fluorescence light microscopy methods, with the ability to spectrally resolve nanometre scale distributions of multiple molecular targets. In conjunction with the next generation of electron microscopy, SMLM has allowed the visualisation and quantification of intricate t-tubule morphologies within large areas of muscle cells at an unprecedented level of detail. In this paper, we review recent advancements in the t-tubule structural biology with the utility of various microscopy techniques. We outline the technical considerations in adapting SMLM to study t-tubules and its potential to further our understanding of the molecular processes that underlie the sub-micron scale structural alterations observed in a range of muscle pathologies. PMID:26913143

  9. Time Course of the Response of Myofibrillar and Sarcoplasmic Protein Metabolism to Unweighting of the Soleus Muscle

    NASA Technical Reports Server (NTRS)

    Munoz, Kathryn A.; Satarug, Soisungwan; Tischler, Marc E.

    1993-01-01

    Contributions of altered in vivo protein synthesis and degradation to unweighting atrophy of the soleus muscle in tail-suspended young female rats were analyzed daily for up to 6 days. Specific changes in myofibrillar and sarcoplasmic proteins were also evaluated to assess their contributions to the loss of total protein. Synthesis of myofibrillar and sarcoplasmic proteins was estimated by intramuscular (IM) injection and total protein by intraperitoneal (IP) injection of flooding doses of H-3-phenylaianine. Total protein loss was greatest during the first 3 days following suspension and was a consequence of the loss of myofibrillar rather than sarcoplasmic proteins. However, synthesis of total myofibrillar and sarcoplasmic proteins diminished in parallel beginning in the first 24 hours. Therefore sarcoplasmic proteins must be spared due to a decrease in their degradation. In contrast, myofibrillar protein degradation increased, thus explaining the elevated degradation of the total pool. Following 72 hours of suspension, protein synthesis remained low, but the rate of myofibrillar protein loss diminished, suggesting a slowing of degradation. These various results show acute loss of protein during unweighting atrophy is a consequence of decreased synthesis and increased degradation of myofibrillar proteins, and sarcoplasmic proteins are spared due to slower degradation, likely explaining the sparing of plasma membrane receptors. Based on other published data, we propose that the slowing of atrophy after the initial response may be attributed to an increased effect of insulin.

  10. Increased cytosolic androgen receptor binding in rat striated muscle following denervation and disuse

    NASA Technical Reports Server (NTRS)

    Bernard, P. A.; Fishman, P. S.; Max, S. R.; Rance, N. E.

    1984-01-01

    The effects of denervation and disuse on cytosolic androgen receptor binding by rat striated muscle are investigated. Denervation of the extensor digitorum longus and tibialis anterior muscles caused by a 40-50-percent increase in cytosolic androgen receptor concentration with no change in apparent binding affinity. This effect was evident at 6 h postdenervation, maximal at 24 h, and declined to 120 percent of the control level 72 h after denervation. A 40-percent increase in cytosolic androgen receptor concentration was also noted 24 hr after denervation of the hormone-sensitive levator ani muscle. The effect of denervation on androgen receptors was blocked by in vivo injection of cycloheximide; therefore, de novo receptor synthesis probably is not involved in the observed increase. Disuse, produced by subperineurial injection of tetrodotoxin into the tibial and common peroneal branches of the sciatic nerve, mimicked the effect of denervation on androgen receptor binding, suggesting that neuromuscular activity is important in regulation of receptor concentration. Possible mechanisms subserving this effect are discussed.

  11. Characterization of beta-connectin (titin 2) from striated muscle by dynamic light scattering.

    PubMed Central

    Higuchi, H; Nakauchi, Y; Maruyama, K; Fujime, S

    1993-01-01

    Connectin (titin) is a large filamentous protein (single peptide) with a molecular mass of approximately 3 MDa, contour length approximately 900 nm, and diameter approximately 4 nm, and resides in striated muscle. Connectin links the thick filaments to the Z-lines in a sarcomere and produces a passive elastic force when muscle fiber is stretched. The aim of this study is to elucidate some aspects of physical properties of isolated beta-connectin (titin 2), a proteolytic fragment of connectin, by means of dynamic light-scattering (DLS) spectroscopy. The analysis of DLS spectra for beta-connectin gave the translational diffusion coefficient of 3.60 x 10(-8) cm2/s at 10 degrees C (or the hydrodynamic radius of 44.1 nm), molecular mass little smaller than 3.0 MDa (for a literature value of sedimentation coefficient), the root-mean-square end-to-end distance of 163 nm (or the radius of gyration of 66.6 nm), and the Kuhn segment number of 30 and segment length of 30 nm (or the persistence length of 15 nm). These results permitted to estimate the flexural rigidity of 6.0 x 10(-20) dyn x cm2 for filament bending, and the elastic constant of 7 dyn/cm for extension of one persistence length. Based on a simple model, implications of the present results in muscle physiology are discussed. Images FIGURE 1 PMID:8298020

  12. Inhibition of the Ca sup 2+ -ATPase of vascular smooth muscle sarcoplasmic reticulum by superoxide radicals

    SciTech Connect

    Suzuki, Yuichiro; Ford, G.D. )

    1991-03-15

    The effect of oxygen free radicals generated by hypoxanthine plus xanthine oxidase on the Ca{sup 2+}-ATPase of sarcoplasmic reticulum from bovine aortic smooth muscle were studied. Exogenous hypoxanthine plus xanthine oxidase produced an hypoxanthine concentration dependent inhibition of the Ca{sup 2+}-ATPase. The inhibition could be completely blocked by superoxide dismutase but not by either mannitol or deferoxamine. Direct addition of reagent hydrogen peroxide in the {mu}M range did not cause significant inhibition. These results suggest that superoxide is the primary damaging species. Additionally, 1.16 {plus minus} 0.17 mU/g wet wt of xanthine oxidase activity were detected in the post-nuclear supernatant of bovine aortic smooth muscle, suggesting the existence of a possible intracellular source of superoxide. This value was calculated to be approximately 5 mU/ml by using a usual value of vascular smooth muscle cellular volume. Thus the level of endogenous xanthine oxidase resident in vascular smooth muscle is comparable with the level of exogenous xanthine oxidase used in the present study. These findings suggest a potential role of xanthine oxidase-generated superoxide in free radical injury to vascular smooth muscle.

  13. Large-scale Models Reveal the Two-component Mechanics of Striated Muscle

    PubMed Central

    Jarosch, Robert

    2008-01-01

    This paper provides a comprehensive explanation of striated muscle mechanics and contraction on the basis of filament rotations. Helical proteins, particularly the coiled-coils of tropomyosin, myosin and α-actinin, shorten their H-bonds cooperatively and produce torque and filament rotations when the Coulombic net-charge repulsion of their highly charged side-chains is diminished by interaction with ions. The classical “two-component model” of active muscle differentiated a “contractile component” which stretches the “series elastic component” during force production. The contractile components are the helically shaped thin filaments of muscle that shorten the sarcomeres by clockwise drilling into the myosin cross-bridges with torque decrease (= force-deficit). Muscle stretch means drawing out the thin filament helices off the cross-bridges under passive counterclockwise rotation with torque increase (= stretch activation). Since each thin filament is anchored by four elastic α-actinin Z-filaments (provided with force-regulating sites for Ca2+ binding), the thin filament rotations change the torsional twist of the four Z-filaments as the “series elastic components”. Large scale models simulate the changes of structure and force in the Z-band by the different Z-filament twisting stages A, B, C, D, E, F and G. Stage D corresponds to the isometric state. The basic phenomena of muscle physiology, i. e. latency relaxation, Fenn-effect, the force-velocity relation, the length-tension relation, unexplained energy, shortening heat, the Huxley-Simmons phases, etc. are explained and interpreted with the help of the model experiments. PMID:19330099

  14. Drop in endo/sarcoplasmic calcium precedes the unfolded protein response in Brefeldin A-treated vascular smooth muscle cells.

    PubMed

    Ziomek, Gabriela; van Breemen, Cornelis; Esfandiarei, Mitra

    2015-10-01

    The present study addresses the causal relationship between induction of endo/sarcoplasmic reticulum stress and dysregulation of calcium transport, while examining whether the most widely-used experimental endo/sarcoplasmic reticulum stressors can be considered appropriate for elucidating underlying cellular mechanisms involved during the progression of the unfolded protein response in vascular smooth muscle cells. Brefeldin A is most commonly cited as inducing the stress response through an accumulation of unfolded proteins in the lumen as a result of a blockage of protein transport from the endo/sarcoplasmic reticulum to the Golgi apparatus. We investigated the effects of Brefeldin A on cellular calcium regulation during the the unfolded protein response in cultured rat vascular smooth muscle cells. Acute exposure of cells to Brefeldin A caused a small transient increase in cytoplasmic calcium, which did not cause a significant decrease in endo/sarcoplasmic reticulum calcium content. However, over the time course of 0-12 h post-treatment with Brefeldin A, we observed that the endo/sarcoplasmic reticulum of vascular smooth muscle cells exhibited an approximate fifty percent decrease in calcium concentration after the first hour of exposure, which is maintained over the next eleven hours, whereas concentrations of unfolded protein response markers only began to increase significantly around nine to twelve hours post-treatment. We have concluded that the endo/sarcoplasmic reticulum calcium drop, which up to now, has been considered as a characteristic of the late onset of cellular stress response, occurs prior to the initiation of the unfolded protein response, rather than as a result of its many corrective pathways. PMID:26172080

  15. Involvement of catecholaminergic neurons in motor innervation of striated muscle in the mouse esophagus.

    PubMed

    van der Keylen, Piet; Garreis, Fabian; Steigleder, Ruth; Sommer, Daniel; Neuhuber, Winfried L; Wörl, Jürgen

    2016-05-01

    Enteric co-innervation is a peculiar innervation pattern of striated esophageal musculature. Both anatomical and functional data on enteric co-innervation related to various transmitters have been collected in different species, although its function remains enigmatic. However, it is unclear whether catecholaminergic components are involved in such a co-innervation. Thus, we examined to identify catecholaminergic neuronal elements and clarify their relationship to other innervation components in the esophagus, using immunohistochemistry with antibodies against tyrosine hydroxylase (TH), vesicular acetylcholine transporter (VAChT), choline acetyltransferase (ChAT) and protein gene product 9.5 (PGP 9.5), α-bungarotoxin (α-BT) and PCR with primers for amplification of cDNA encoding TH and dopamine-β-hydroxylase (DBH). TH-positive nerve fibers were abundant throughout the myenteric plexus and localized on about 14% of α-BT-labelled motor endplates differing from VAChT-positive vagal nerve terminals. TH-positive perikarya represented a subpopulation of only about 2.8% of all PGP 9.5-positive myenteric neurons. Analysis of mRNA showed both TH and DBH transcripts in the mouse esophagus. As ChAT-positive neurons in the compact formation of the nucleus ambiguus were negative for TH, the TH-positive nerve varicosities on motor endplates are presumably of enteric origin, although a sympathetic origin cannot be excluded. In the medulla oblongata, the cholinergic ambiguus neurons were densely supplied with TH-positive varicosities. Thus, catecholamines may modulate vagal motor innervation of esophageal-striated muscles not only at the peripheral level via enteric co-innervation but also at the central level via projections to the nucleus ambiguus. As Parkinson's disease, with a loss of central dopaminergic neurons, also affects the enteric nervous system and dysphagia is prevalent in patients with this disease, investigation of intrinsic catecholamines in the esophagus may

  16. Induction of calcium release from sarcoplasmic reticulum of skeletal muscle by xanthone and norathyriol.

    PubMed Central

    Kang, J. J.; Cheng, Y. W.; Ko, F. N.; Kuo, M. L.; Lin, C. N.; Teng, C. M.

    1996-01-01

    1. Effects of xanthone and its derivative, 1,3,6,7-tetrahydroxyxanthone (norathyriol), on Ca2+ release and ryanodine binding were studied in isolated sarcoplasmic reticulum (SR) vesicles from rabbit skeletal muscle. 2. Both xanthone and norathyriol dose-dependently induced Ca2+ release from the actively loaded SR vesicles which was blocked by ruthenium red, a specific Ca2+ release inhibitor, and Mg2+. 3. Xanthone and norathyriol also dose-dependently increased apparent [3H]-ryanodine binding. Norathyriol, but not xanthone, produced a synergistic effect on binding activation when added concurrently with caffeine. 4. In the presence of Mg2+, which inhibits ryanodine binding, both caffeine and norathyriol, but not xanthone, could restore the binding to the level observed in the absence of Mg2+. 5. Xanthone activated the Ca(2+)-ATPase activity of isolated SR vesicles dose-dependently reaching 70% activation at 300 microM. 6. When tested in mouse diaphragm, norathyriol potentiated the muscle contraction followed by twitch depression and contracture in either a Ca(2+) -free bathing solution or one containing 2.5 mM Ca2+. These norathyriol-induced effects on muscle were inhibited by pretreatment with ruthenium red or ryanodine. 7. These data suggest that xanthone and norathyriol can induce Ca2+ release from the SR of skeletal muscle through a direct interaction with the Ca2+ release channel, also known as the ryanodine receptor. Images Figure 6 PMID:8842439

  17. Induction of skeletal muscle contracture and calcium release from isolated sarcoplasmic reticulum vesicles by sanguinarine

    PubMed Central

    Hu, C M; Cheng, H W; Cheng, Y W; Kang, J J

    2000-01-01

    The benzophenanthrine alkaloid, sanguinarine, was studied for its effects on isolated mouse phrenic-nerve diaphragm preparations. Sanguinarine induced direct, dose-dependent effects on muscle contractility. Sanguinarine-induced contracture was partially inhibited when the extracellular Ca2+ was removed or when the diaphragm was pretreated with nifedipine. Depletion of sarcoplasmic reticulum (SR) internal calcium stores completely blocked the contracture. Sanguinarine induced Ca2+ release from the actively loaded SR vesicles was blocked by ruthenium red and dithiothreitol (DTT), consistent with the ryanodine receptor (RyR) as the site of sanguinarine action. Sanguinarine altered [3H]-ryanodine binding to the RyR of isolated SR vesicles, potentiating [3H]-ryanodine binding at lower concentrations and inhibiting binding at higher concentrations. All of these effects were reversed by DTT, suggesting that sanguinarine-induced Ca2+ release from SR occurs through oxidation of critical SH groups of the RyR SR calcium release channel. PMID:10807666

  18. Dietary Fish Oil Blocks the Microcirculatory Manifestations of Ischemia- Reperfusion Injury in Striated Muscle in Hamsters

    NASA Astrophysics Data System (ADS)

    Lehr, Hans-Anton; Hubner, Christoph; Nolte, Dirk; Kohlschutter, Alfried; Messmer, Konrad

    1991-08-01

    Epidemiologic observations and experimental studies have demonstrated a protective effect of dietary fish oil on the clinical manifestations of ischemia-reperfusion injury. To investigate the underlying mechanisms, we used the dorsal skinfold chamber model for intravital fluorescence microscopy of the microcirculation in striated muscle of awake hamsters. In control hamsters (n = 7), reperfusion after a 4-hr pressure-induced ischemia to the muscle tissue elicited the adhesion of fluorescently stained leukocytes to the endothelium of postcapillary venules, capillary obstruction, and the breakdown of endothelial integrity. These microvascular manifestations of ischemia-reperfusion injury were significantly attenuated in animals (n = 7) when fed with a fish oil-enriched diet for 4 weeks prior to the experiments. In leukocyte total lipids, the fish oil diet resulted in a substantial displacement of arachidonic acid, the precursor of the potent adhesionpromoting leukotriene (LT) B_4, by fish oil-derived eicosapentaenoic acid, the precursor of biologically less potent LTB_5, emphasizing the mediator role of LTB_4 in ischemia-reperfusion injury. These results suggest that the preservation of microvascular perfusion by dietary fish oil contributes to its protective effects on the clinical manifestations of ischemia-reperfusion injury.

  19. Pulsed nuclear magnetic resonance study of 39K in frog striated muscle.

    PubMed Central

    Civan, M M; McDonald, G G; Pring, M; Shporer, M

    1976-01-01

    Samples of 1 M KCl solution and 10 samples of intact frog striated muscle were studied at 4-7 degrees C and/or at 21-22 degrees C. Field inhomogeneity was minimized by using small sample volumes and by using a superconducting magnet designed specifically to provide highly homogeneous fields. In the present experiments, magnetic field inhomogeneity was measured to contribute less than 15% to the free induction decay observed for intracellular 39K. The signal-to-noise ratio of the measurements was enhanced by means of extensive time-averaging. The rates of nuclear relaxation for 39K in aqueous solution were 22 +/- 3 (mean +/- 95% confidence limits) s-1 at 4-7 degrees C and 15 +/- 2 s-1 at 21-22 degrees C. For intracellular 39K, (1/T2) was measured to be 327 +/- 22 s-1 and 229 +/- 10 s-1 at the lower and higher temperatures, respectively. The corresponding values for (1/T1) in the same muscle samples were 198 +/- 31 s-1 and 79 +/- 15 s-1 at 4-7 degrees C and at 21-22 degrees C, respectively. These results for 39K are similar to those previously obtained for intracellular 23Na. Since less than 1% of the intracellular 23Na has been estimated to be immobilized, fractional immobilization of intracellular 39K is also likely to be insubstantial. PMID:1086686

  20. The Intriguing Dual Lattices of the Myosin Filaments in Vertebrate Striated Muscles: Evolution and Advantage

    PubMed Central

    Luther, Pradeep K.; Squire, John M.

    2014-01-01

    Myosin filaments in vertebrate striated muscle have a long roughly cylindrical backbone with cross-bridge projections on the surfaces of both halves except for a short central bare zone. In the middle of this central region the filaments are cross-linked by the M-band which holds them in a well-defined hexagonal lattice in the muscle A-band. During muscular contraction the M-band-defined rotation of the myosin filaments around their long axes influences the interactions that the cross-bridges can make with the neighbouring actin filaments. We can visualise this filament rotation by electron microscopy of thin cross-sections in the bare-region immediately adjacent to the M-band where the filament profiles are distinctly triangular. In the muscles of teleost fishes, the thick filament triangular profiles have a single orientation giving what we call the simple lattice. In other vertebrates, for example all the tetrapods, the thick filaments have one of two orientations where the triangles point in opposite directions (they are rotated by 60° or 180°) according to set rules. Such a distribution cannot be developed in an ordered fashion across a large 2D lattice, but there are small domains of superlattice such that the next-nearest neighbouring thick filaments often have the same orientation. We believe that this difference in the lattice forms can lead to different contractile behaviours. Here we provide a historical review, and when appropriate cite recent work related to the emergence of the simple and superlattice forms by examining the muscles of several species ranging back to primitive vertebrates and we discuss the functional differences that the two lattice forms may have. PMID:25478994

  1. Digital image analysis of striated skeletal muscle tissue injury during reperfusion after induced ischemia

    NASA Astrophysics Data System (ADS)

    Rosero Salazar, Doris Haydee; Salazar Monsalve, Liliana

    2015-01-01

    Conditions such as surgical procedures or vascular diseases produce arterial ischemia and reperfusion injuries, which generate changes in peripheral tissues and organs, for instance, in striated skeletal muscle. To determine such changes, we conducted an experimental method in which 42 male Wistar rat were selected, to be undergone to tourniquet application on the right forelimb and left hind limb, to induce ischemia during one and three hours, followed by reperfusion periods starting at one hour and it was prolonged up to 32 days. Extensor carpi radialis longus and soleus respectively, were obtained to be processed for histochemical and morphometric analysis. By means of image processing and detection of regions of interest, variations of areas occupied by muscle fibers and intramuscular extracellular matrix (IM-ECM) throughout reperfusion were observed. In extensor carpi radialis longus, results shown reduction in the area occupied by muscle fibers; this change is significant between one hour and three hours ischemia followed by 16 hours, 48 hours and 32 days reperfusión (p˂0.005). To compare only periods of reperfusión that continued to three hours ischemia, were found significant differences, as well. For area occupied by IM-ECM, were identified increments in extensor carpi radialis longus by three hours ischemia and eight to 16 days reperfusion; in soleus, was observed difference by one hour ischemia with 42 hours reperfusion, and three hours ischemia followed by four days reperfusion (p˂0.005). Skeletal muscle develops adaptive changes in longer reperfusion, to deal with induced injury. Descriptions beyond 32 days reperfusion, can determine recovering normal pattern.

  2. Effect of disuse on sarcoplasmic reticulum in fast and slow skeletal muscle

    NASA Technical Reports Server (NTRS)

    Kim, D. H.; Witzmann, F. A.; Fitts, R. H.

    1982-01-01

    The effect of 6 weeks of hindlimb immobilization on rat skeletal muscle sarcoplasmic reticulum (SR) was determined in the slow-twitch, type 1 soleus (SOL), the fast-twitch, type 2A deep region of the vastus lateralis (DVL), and the fast-twitch, type 2B superficial region of the vastus lateralis (SVL). Immobilization produced a significant decline in the Ca(2+) uptake rate (V sub max) of SR vesicles from the slow SOL, while the SR V sub max increased in the fast SVL and was unaltered in the DVL. Vesicles from the fast SVL and DVL also exhibited a higher total Ca(2+) uptake capacity following immobilization. An evaluation of the time course of the immobilization-mediated effect revealed an increased Ca(2+) uptake capacity in all three samples after 1 wk. In the SOL total Ca(2+) uptake returned to control level after 2 wk, while in the fast-twitch muscles the higher capacities were maintained. The Ca(2+)-stimulated SR ATPase activity was not altered in any of the muscle studies.

  3. Mastoparan binds to glycogen phosphorylase to regulate sarcoplasmic reticular Ca2+ release in skeletal muscle.

    PubMed Central

    Hirata, Yutaka; Atsumi, Masanori; Ohizumi, Yasushi; Nakahata, Norimichi

    2003-01-01

    The ryanodine receptor, a Ca(2+)-releasing channel in sarcoplasmic reticulum (SR), plays an important role in the excitation-contraction coupling of skeletal muscle. In a previous study [Hirata, Nakahata and Ohizumi (2000) Mol. Pharmacol. 57, 1235-1242], we reported that mastoparan caused Ca(2+) release through ryanodine receptor from the heavy fraction of SR (HSR) isolated from rabbit skeletal muscle, and that it specifically bound to a 97 kDa protein which was distinct from Ca(2+)-pump or triadin. The present study was undertaken to identify and characterize the 97 kDa mastoparan-binding protein. The 97 kDa protein was purified from solubilized HSR by DEAE-Sepharose column chromatography and preparative SDS/PAGE. The partial amino acid sequence of the purified 97 kDa protein was matched with that of glycogen phosphorylase (GP). The proteolytic cleavage pattern of the 97 kDa protein was identical with that of GP. Furthermore, [(125)I-Tyr(3)]mastoparan specifically bound to GP. Interestingly, mastoparan-induced Ca(2+) release was inhibited by exogenous addition of GP-a, and mastoparan dissociated GP from HSR. These results indicate that the 97 kDa mastoparan-binding protein is GP, which negatively regulates Ca(2+) release from HSR. There may be a functional cross-talk between Ca(2+) release from HSR and glycogenolysis for energy supply mediated through GP in skeletal muscles. PMID:12519071

  4. Lessons from mammalian hibernators: molecular insights into striated muscle plasticity and remodeling.

    PubMed

    Tessier, Shannon N; Storey, Kenneth B

    2016-05-01

    Striated muscle shows an amazing ability to adapt its structural apparatus based on contractile activity, loading conditions, fuel supply, or environmental factors. Studies with mammalian hibernators have identified a variety of molecular pathways which are strategically regulated and allow animals to endure multiple stresses associated with the hibernating season. Of particular interest is the observation that hibernators show little skeletal muscle atrophy despite the profound metabolic rate depression and mechanical unloading that they experience during long weeks of torpor. Additionally, the cardiac muscle of hibernators must adjust to low temperature and reduced perfusion, while the strength of contraction increases in order to pump cold, viscous blood. Consequently, hibernators hold a wealth of knowledge as it pertains to understanding the natural capacity of myocytes to alter structural, contractile and metabolic properties in response to environmental stimuli. The present review outlines the molecular and biochemical mechanisms which play a role in muscular atrophy, hypertrophy, and remodeling. In this capacity, four main networks are highlighted: (1) antioxidant defenses, (2) the regulation of structural, contractile and metabolic proteins, (3) ubiquitin proteosomal machinery, and (4) macroautophagy pathways. Subsequently, we discuss the role of transcription factors nuclear factor (erythroid-derived 2)-like 2 (Nrf2), Myocyte enhancer factor 2 (MEF2), and Forkhead box (FOXO) and their associated posttranslational modifications as it pertains to regulating each of these networks. Finally, we propose that comparing and contrasting these concepts to data collected from model organisms able to withstand dramatic changes in muscular function without injury will allow researchers to delineate physiological versus pathological responses. PMID:26982616

  5. Testosterone enhances C-14 2-deoxyglucose uptake by striated muscle. [sex hormones and muscle

    NASA Technical Reports Server (NTRS)

    Toop, J.; Max, S. R.

    1982-01-01

    The effect of testosterone propionate (TP) on C-14 2-deoxyglucose (C-14 2DG) uptake was studied in the rat levator ani muscle in vivo using the autoradiographic technique. Following a delay of 1 to 3 h after injecting TP, the rate of C-14 2DG uptake in experimental animals began to increase and continued to increase for at least 20 h. The label, which corresponds to C-14 2-deoxyglucose 6-phosphate, as demonstrated by chromatographic analysis of muscle extracts, was uniformly distributed over the entire muscle and was predominantly in muscle fibers, although nonmuscular elements were also labeled. The 1 to 3 h time lag suggests that the TP effect may be genomic, acting via androgen receptors, rather than directly on muscle membranes. Acceleration of glucose uptake may be an important early event in the anabolic response of the rat levator ani muscle to androgens.

  6. Two distinct distribution patterns of sarcoplasmic reticulum in two functionally different giant smooth muscle cells of Beroe ovata.

    PubMed

    Cario, C; Malaval, L; Hernandez-Nicaise, M L

    1995-12-01

    The sarcoplasmic reticulum has been studied in radial and longitudinal giant smooth muscle fibres of the marine planktonic invertebrate Beroe. Impregnation with heavy metals has revealed that the smooth component is organised in a longitudinally oriented three-dimensional network of tubules running along the myofilaments. An ultrastructural morphometric analysis has shown that the relative volume of the sarcoplasmic reticulum is the same (1% of the myofilament volume) in both fibres but that the size, number and distribution of the sarcoplasmic reticulum tubules differ significantly. The longitudinal fibres are characterised physiologically by an action potential with a short calcium-dependent plateau that can trigger a short contraction; radial fibres produce action potentials without a plateau and their contraction requires a train of spikes. The sarcoplasmic reticulum tubules in longitudinal fibres are thinner (132 nm in diameter) and more numerous than those in radial fibres (160 nm in diameter). Moreover, the tubules are homogeneously distributed among the myofilaments in radial fibres, whereas they are more numerous in the centre of longitudinal muscles. PMID:8581937

  7. Role of glycogen availability in sarcoplasmic reticulum Ca2+ kinetics in human skeletal muscle

    PubMed Central

    Ørtenblad, Niels; Nielsen, Joachim; Saltin, Bengt; Holmberg, Hans-Christer

    2011-01-01

    Little is known about the precise mechanism that relates skeletal muscle glycogen to muscle fatigue. The aim of the present study was to examine the effect of glycogen on sarcoplasmic reticulum (SR) function in the arm and leg muscles of elite cross-country skiers (n= 10, 72 ± 2 ml kg−1 min−1) before, immediately after, and 4 h and 22 h after a fatiguing 1 h ski race. During the first 4 h recovery, skiers received either water or carbohydrate (CHO) and thereafter all received CHO-enriched food. Immediately after the race, arm glycogen was reduced to 31 ± 4% and SR Ca2+ release rate decreased to 85 ± 2% of initial levels. Glycogen noticeably recovered after 4 h recovery with CHO (59 ± 5% initial) and the SR Ca2+ release rate returned to pre-exercise levels. However, in the absence of CHO during the first 4 h recovery, glycogen and the SR Ca2+ release rate remained unchanged (29 ± 2% and 77 ± 8%, respectively), with both parameters becoming normal after the remaining 18 h recovery with CHO. Leg muscle glycogen decreased to a lesser extent (71 ± 10% initial), with no effects on the SR Ca2+ release rate. Interestingly, transmission electron microscopy (TEM) analysis revealed that the specific pool of intramyofibrillar glycogen, representing 10–15% of total glycogen, was highly significantly correlated with the SR Ca2+ release rate. These observations strongly indicate that low glycogen and especially intramyofibrillar glycogen, as suggested by TEM, modulate the SR Ca2+ release rate in highly trained subjects. Thus, low glycogen during exercise may contribute to fatigue by causing a decreased SR Ca2+ release rate. PMID:21135051

  8. The sarcoplasmic reticulum: then and now.

    PubMed

    Somlyo, Andrew P; Somlyo, Avril V

    2002-01-01

    Structural and functional studies indicate the important role of the sarcoplasmic reticulum (SR) in excitation-contraction coupling in smooth and striated muscles, as well as a similar Ca2+ signalling function of the endoplasmic reticulum (ER) in non-muscle cells. Electron probe analysis directly established the SR/ER of smooth muscle as a sink and source of Ca2+, while immunoelectron and immunofluorescence microscopy showed both inositol-1,4,5-trisphosphate (InsP3) and ryanodine receptors localized to its membranes. Structural relationships, some yet to have fully determined functions, occur between the mitochondria and the SR, and the junctional SR and plasma membrane. Ca2+ is released by stimuli that generate InsP3 indicating the primary role of InsP3 receptors in Ca2+-release in smooth, although not in striated, muscle. Pathological mitochondrial Ca2+ uptake occurs at high [Ca2+]i similarly in both muscle and non-muscle cells. Based on newer evidence, earlier experimental results obtained with fluorescent Ca2+ indicators and related to phasic and tonic components of contraction can now be reinterpreted. Electron energy loss spectroscopy for high-resolution Ca2+ imaging and flash photolysis of caged agonists for exploration of the rapid kinetics of Ca2+ release from the SR are currently being explored. PMID:12164313

  9. A calcium antagonist drug binding site in skeletal muscle sarcoplasmic reticulum: evidence for a calcium channel.

    PubMed

    Fairhurst, A S; Thayer, S A; Colker, J E; Beatty, D A

    1983-03-21

    The sarcoplasmic reticulum (S.R.) of rabbit skeletal muscle has been found to contain a single, high affinity binding site for the Ca antagonist drug [3H]-nitrendipine. Two subfractions of the reticulum were studied, the heavy (HSR) and light (LSR) preparations, which exhibited similar nitrendipine equilibrium dissociation constants (KD) of 1nM. Crude cardiac and brain membranes assayed under the same conditions exhibited KD values of 0.2-0.3nM. The concentration of binding sites per mg. protein (Bmax) in HSR was found to be very high, namely 6.7 picomoles/mg, some four times greater than that of LSR. [3H]-nitrendipine binding to HSR was reversible and inhibited by the Ca antagonists flunarizine and verapamil, and by the intracellular Ca release antagonist TMB-8 (8-diethylamino-octyl 3,4,5-trimethylbenzoate hydrochloride). However, unlabelled nitrendipine at 2 X 10(-5)M had no effect on contraction of isolated electrically stimulated rabbit lumbrical or rat diaphragm muscles, nor did it affect the neuromuscular junction as studied in rat phrenic nerve-diaphragm preparations. Also, little effect of 2 X 10(-5)M nitrendipine was seen on net 45Ca uptake by HSR. These results suggest that [3H]-nitrendipine binding to skeletal muscle S.R. resembles that of brain membranes, which also contain a high affinity binding site for [3H]-nitrendipine and which similarly are pharmacologically insensitive to this dihydropyridine type of Ca channel blocking agent. Since HSR is also enriched in calsequestrin and terminal cysternae from which Ca is released in vivo, it seems likely that the [3H]-nitrendipine binding sites in S.R. are associated with Ca channels in the S.R. PMID:6300579

  10. Mitochondrial DNA structure and expression in specialized subtypes of mammalian striated muscle.

    PubMed Central

    Annex, B H; Williams, R S

    1990-01-01

    Mitochondrial DNA (mt DNA) in cells of vertebrate organisms can assume an unusual triplex DNA structure known as the displacement loop (D loop). This triplex DNA structure forms when a partially replicated heavy strand of mtDNA (7S mtDNA) remains annealed to the light strand, displacing the native heavy strand in this region. The D-loop region contains the promoters for both heavy- and light-strand transcription as well as the origin of heavy-strand replication. However, the distribution of triplex and duplex forms of mtDNA in relation to respiratory activity of mammalian tissues has not been systematically characterized, and the functional significance of the D-loop structure is unknown. In comparisons of specialized muscle subtypes within the same species and of the same muscle subtype in different species, the relative proportion of D-loop versus duplex forms of mtDNA in striated muscle tissues of several mammalian species demonstrated marked variation, ranging from 1% in glycolytic fast skeletal fibers of the rabbit to 65% in the mouse heart. There was a consistent and direct correlation between the ratio of triplex to duplex forms of mtDNA and the capacity of these tissues for oxidative metabolism. The proportion of D-loop forms likewise correlated directly with mtDNA copy number, mtRNA abundance, and the specific activity of the mtDNA (gamma) polymerase. The D-loop form of mtDNA does not appear to be transcribed at greater efficiency than the duplex form, since the ratio of mtDNA copy number to mtRNA was unrelated to the proportion of triplex mtDNA genomes. However, tissues with a preponderance of D-loop forms tended to express greater levels of cytochrome b mRNA relative to mitochondrial rRNA transcripts, suggesting that the triplex structure may be associated with variations in partial versus full-length transcription of the heavy strand. Images PMID:1700273

  11. Alteration of Sarcoplasmic Reticulum Ca2+ Release in Skeletal Muscle from Calpain 3-Deficient Mice

    PubMed Central

    Dayanithi, Govindan; Richard, Isabelle; Viero, Cédric; Mazuc, Elsa; Mallie, Sylvie; Valmier, Jean; Bourg, Nathalie; Herasse, Muriel; Marty, Isabelle; Lefranc, Gérard; Mangeat, Paul; Baghdiguian, Stephen

    2009-01-01

    Mutations of Ca2+-activated proteases (calpains) cause muscular dystrophies. Nevertheless, the specific role of calpains in Ca2+ signalling during the onset of dystrophies remains unclear. We investigated Ca2+ handling in skeletal cells from calpain 3-deficient mice. [Ca2+]i responses to caffeine, a ryanodine receptor (RyR) agonist, were decreased in −/− myotubes and absent in −/− myoblasts. The −/− myotubes displayed smaller amplitudes of the Ca2+ transients induced by cyclopiazonic acid in comparison to wild type cells. Inhibition of L-type Ca2+ channels (LCC) suppressed the caffeine-induced [Ca2+]i responses in −/− myotubes. Hence, the absence of calpain 3 modifies the sarcoplasmic reticulum (SR) Ca2+ release, by a decrease of the SR content, an impairment of RyR signalling, and an increase of LCC activity. We propose that calpain 3-dependent proteolysis plays a role in activating support proteins of intracellular Ca2+ signalling at a stage of cellular differentiation which is crucial for skeletal muscle regeneration. PMID:20300593

  12. Dynamic measurement of the calcium buffering properties of the sarcoplasmic reticulum in mouse skeletal muscle

    PubMed Central

    Manno, Carlo; Sztretye, Monika; Figueroa, Lourdes; Allen, Paul D; Ríos, Eduardo

    2013-01-01

    The buffering power, B, of the sarcoplasmic reticulum (SR), ratio of the changes in total and free [Ca2+], was determined in fast-twitch mouse muscle cells subjected to depleting membrane depolarization. Changes in total SR [Ca2+] were measured integrating Ca2+ release flux, determined with a cytosolic [Ca2+] monitor. Free [Ca2+]SR was measured using the cameleon D4cpv-Casq1. In 34 wild-type (WT) cells average B during the depolarization (ON phase) was 157 (SEM 26), implying that of 157 ions released, 156 were bound inside the SR. B was significantly greater when BAPTA, which increases release flux, was present in the cytosol. B was greater early in the pulse – when flux was greatest – than at its end, and greater in the ON than in the OFF. In 29 Casq1-null cells, B was 40 (3.6). The difference suggests that 75% of the releasable calcium is normally bound to calsequestrin. In the nulls the difference in B between ON and OFF was less than in the WT but still significant. This difference and the associated decay in B during the ON were not artifacts of a slow SR monitor, as they were also found in the WT when [Ca2+]SR was tracked with the fast dye fluo-5N. The calcium buffering power, binding capacity and non-linear binding properties of the SR measured here could be accounted for by calsequestrin at the concentration present in mammalian muscle, provided that its properties were substantially different from those found in solution. Its affinity should be higher, or KD lower than the conventionally accepted 1 mm; its cooperativity (n in a Hill fit) should be higher and the stoichiometry of binding should be at the higher end of the values derived in solution. The reduction in B during release might reflect changes in calsequestrin conformation upon calcium loss. PMID:23148320

  13. Activations of the Ca dependent K channel by Ca released from the sarcoplasmic reticulum of mammalian smooth muscles.

    PubMed

    Kitamura, K; Sakai, T; Kajioka, S; Kuriyama, H

    1989-01-01

    In mammalian smooth muscles, the outward K current recorded using the whole cell voltage clamp or patch clamp methods can be classified into the Ca-dependent and independent K currents. The former is sub-classified into the extra- and intra-cellular Ca dependent K current. The intra-cellular Ca dependent K current has a close relation to Ca released from the sarcoplasmic reticulum, i.e. Ca released by inositol 1,4,5-trisphosphate (InsP3), ryanodine or Ca ionophores (A23187 or ionomycin) modify the appearance of the K current. The transient (Ca dependent) outward current evoked by depolarization pulses, as measured using the whole cell voltage clamp method, is closely related with after-hyperpolarization of the action potential as recorded using the microelectrode method and is postulated to be due to activations of the Ca-induced Ca release mechanism in the sarcoplasmic reticulum. The oscillatory (Ca dependent) outward K current is closely related with the amount of Ca released from the sarcoplasmic reticulum during the long depolarization induced by electrical stimulation (command pulse) or applications of Ca releasers such as InsP3 or ryanodine. In this review, the Ca dependent K current recorded from smooth muscle cells is compared with the influx and release of Ca. PMID:2667516

  14. Mitochondrial and sarcoplasmic proteins, but not myosin heavy chain, are sensitive to leucine supplementation in old rat skeletal muscle.

    PubMed

    Guillet, Christelle; Zangarelli, Aude; Mishellany, Anne; Rousset, Paulette; Sornet, Claire; Dardevet, Dominique; Boirie, Yves

    2004-05-01

    Leucine has a major anabolic impact on muscle protein synthesis in young as in old animals. However, myosin heavy chain (MHC), sarcoplasmic and mitochondrial proteins may differently respond to anabolic factors, especially during aging. To test this hypothesis, fractional synthesis rates (FSR) of the three muscle protein fractions were measured using a flooding dose of [1-(13)C] phenylalanine, in gastrocnemius muscle of adult (8 months) and old (22 months) rats, either in postabsorptive state (PA), or 90-120 min after ingestion of a alanine-supplemented meal (PP+A) or a leucine-supplemented meal (PP+L). In adult and old rats, in comparison with PA, leucine stimulated mitochondrial (adult: 0.260+/-0.011 vs 0.238+/-0.012%h(-1); old: 0.289+/-0.010 vs 0.250+/-0.010%h(-1); PP+L vs PA, P<0.05) and sarcoplasmic (adult: 0.182+/-0.011 vs 0.143+/-0.006%h(-1); old: 0.195+/-0.010 vs 0.149+/-0.008%h(-1); PP+L vs PA, P<0.05) protein FSR, but not MHC synthesis in old rats (0.101+/-0.009 vs 0.137+/-0.018%h(-1); PP+L vs PA, P=NS). In conclusion, synthesis of specific muscle protein is activated by leucine supplementation, but MHC may be less sensitive to anabolic factors with aging. PMID:15130669

  15. The myosin interacting-heads motif is present in the relaxed thick filament of the striated muscle of scorpion.

    PubMed

    Pinto, Antonio; Sánchez, Fredi; Alamo, Lorenzo; Padrón, Raúl

    2012-12-01

    Electron microscopy (EM) studies of 2D crystals of smooth muscle myosin molecules have shown that in the inactive state the two heads of a myosin molecule interact asymmetrically forming a myosin interacting-heads motif. This suggested that inactivation of the two heads occurs by blocking of the actin-binding site of one (free head) and the ATP hydrolysis site of the other (blocked head). This motif has been found by EM of isolated negatively stained myosin molecules of unregulated (vertebrate skeletal and cardiac muscle) and regulated (invertebrate striated and vertebrate smooth muscle) myosins, and nonmuscle myosin. The same motif has also been found in 3D-reconstructions of frozen-hydrated (tarantula, Limulus, scallop) and negatively stained (scallop, vertebrate cardiac) isolated thick filaments. We are carrying out studies of isolated thick filaments from other species to assess how general this myosin interacting-heads motif is. Here, using EM, we have visualized isolated, negatively stained thick filaments from scorpion striated muscle. We modified the iterative helical real space reconstruction (IHRSR) method to include filament tilt, and band-pass filtered the aligned segments before averaging, achieving a 3.3 nm resolution 3D-reconstruction. This reconstruction revealed the presence of the myosin interacting-heads motif (adding to evidence that is widely spread), together with 12 subfilaments in the filament backbone. This demonstrates that conventional negative staining and imaging can be used to detect the presence of the myosin interacting-heads motif in helically ordered thick filaments from different species and muscle types, thus avoiding the use of less accessible cryo-EM and low electron-dose procedures. PMID:22982253

  16. Decelerating burst and complex repetitive discharges in the striated muscle of the urethral sphincter, associated with urinary retention in women.

    PubMed Central

    Fowler, C J; Kirby, R S; Harrison, M J

    1985-01-01

    A type of electromyographic activity, formerly referred to as "pseudomyotonia", can be recorded from the striated muscle of the urethral sphincter using a concentric needle electrode. There are two components to this activity, complex repetitive discharges and decelerating bursts. The latter usually dominate recordings and sound very like myotonic discharges. Analysis of these discharges indicates that they are a form of "bizarre repetitive discharge", and as such, result from ephaptic spread of excitation between muscle fibres rather than from excitation arising in the terminal branches of the motor axon. Profuse activity of this type has been found in 15 women with symptoms of urethral dysfunction, including 11 with urinary retention. It is suggested that this activity is associated with a failure of urethral sphincter relaxation. Images PMID:4056803

  17. Depletion of calcium from the sarcoplasmic reticulum during calcium release in frog skeletal muscle.

    PubMed

    Schneider, M F; Simon, B J; Szucs, G

    1987-11-01

    1. Free intracellular calcium transients (delta[Ca2+] were monitored in cut segments of frog skeletal muscle fibres voltage clamped in a double Vaseline-gap chamber and stretched to sarcomere lengths that eliminated fibre movement. The measured calcium transients were used to calculate the rate of calcium release from the sarcoplasmic reticulum (s.r.) as previously described (Melzer, Rios & Schneider, 1984, 1987). 2. Conditioning pulses were found to suppress the rate of calcium release in test pulses applied after the conditioning pulse. Various combinations of conditioning and test pulses were used to investigate the basis of the suppression of calcium release by the conditioning pulse. 3. Using a constant test pulse applied at varying intervals after a constant conditioning pulse, recovery from suppression of release was found to occur in two phases. During the fast phase of recovery, which was completed within about 1 s, the rate of calcium release was smaller and had a different wave form than the unconditioned control release. The early peak in release that is characteristic of the control release wave form was absent or depressed. During the slow phase of recovery, which required about 1 min for completion, the release wave form was the same as control but was simply scaled down compared to the control. 4. Conditioning pulses also slowed the rate of decay of delta[Ca2+] after a constant test pulse, probably due to an increased occupancy by calcium of slowly equilibrating myoplasmic sites that bind some of the calcium released by the conditioning pulse. Since calcium binding to these sites contributes to the decay of delta[Ca2+], their increased occupancy would slow the decay of delta[Ca2+] following the test pulse. This effect was used to estimate the calcium occupancy of the slowly equilibrating sites. 5. Comparison of the time course of the slow recovery from suppression of release following a constant conditioning pulse with the time course of the loss of

  18. Alterations in the sarcoplasmic protein fraction of beef muscle with postmortem aging and hydrodynamic pressure processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Capillary electrophoresis (CE) and reversed-phase high performance liquid chromatography (RP-HPLC) analysis were utilized to detect differences in the sarcoplasmic protein profiles of beef strip loins subjected to aging and hydrodynamic pressure processing (HDP) treatments. At 48 h postmortem, stri...

  19. ZASP Interacts with the Mechanosensing Protein Ankrd2 and p53 in the Signalling Network of Striated Muscle

    PubMed Central

    Martinelli, Valentina C.; Kyle, W. Buck; Kojic, Snezana; Vitulo, Nicola; Li, Zhaohui; Belgrano, Anna; Maiuri, Paolo; Banks, Lawrence; Vatta, Matteo; Valle, Giorgio; Faulkner, Georgine

    2014-01-01

    ZASP is a cytoskeletal PDZ-LIM protein predominantly expressed in striated muscle. It forms multiprotein complexes and plays a pivotal role in the structural integrity of sarcomeres. Mutations in the ZASP protein are associated with myofibrillar myopathy, left ventricular non-compaction and dilated cardiomyopathy. The ablation of its murine homologue Cypher results in neonatal lethality. ZASP has several alternatively spliced isoforms, in this paper we clarify the nomenclature of its human isoforms as well as their dynamics and expression pattern in striated muscle. Interaction is demonstrated between ZASP and two new binding partners both of which have roles in signalling, regulation of gene expression and muscle differentiation; the mechanosensing protein Ankrd2 and the tumour suppressor protein p53. These proteins and ZASP form a triple complex that appears to facilitate poly-SUMOylation of p53. We also show the importance of two of its functional domains, the ZM-motif and the PDZ domain. The PDZ domain can bind directly to both Ankrd2 and p53 indicating that there is no competition between it and p53 for the same binding site on Ankrd2. However there is competition for this binding site between p53 and a region of the ZASP protein lacking the PDZ domain, but containing the ZM-motif. ZASP is negative regulator of p53 in transactivation experiments with the p53-responsive promoters, MDM2 and BAX. Mutations in the ZASP ZM-motif induce modification in protein turnover. In fact, two mutants, A165V and A171T, were not able to bind Ankrd2 and bound only poorly to alpha-actinin2. This is important since the A165V mutation is responsible for zaspopathy, a well characterized autosomal dominant distal myopathy. Although the mechanism by which this mutant causes disease is still unknown, this is the first indication of how a ZASP disease associated mutant protein differs from that of the wild type ZASP protein. PMID:24647531

  20. Comparison of the calcium release channel of cardiac and skeletal muscle sarcoplasmic reticulum by target inactivation analysis

    SciTech Connect

    McGrew, S.G.; Inui, Makoto; Chadwick, C.C.; Boucek, R.J. Jr.; Jung, C.Y.; Fleischer, S. )

    1989-02-07

    The calcium release channel of sarcoplasmic reticulum which triggers muscle contraction in excitation-contraction coupling has recently been isolated. The channel has been found to be morphologically identical with the feet structures of the junctional face membrane of terminal cisternae and consists of an oligomer of a unique high molecular weight polypeptide. In this study, the authors compare the target size of the calcium release channel from heart and skeletal muscle using target inactivation analysis. The target molecular weights of the calcium release channel estimated by measuring ryanodine binding after irradiation are similar for heart (139,000) and skeletal muscle (143,000) and are smaller than the monomeric unit (estimated to be about 360,000). The target size, estimated by measuring polypeptide remaining after irradiation, was essentially the same for heart and skeletal muscle, 1,061,000 and 1,070,000, respectively, indicating an oligomeric association of protomers. Thus, the calcium release channel of both cardiac and skeletal muscle reacts uniquely with regard to target inactivation analysis in that (1) the size by ryanodine binding is smaller than the monomeric unit and (2) a single hit leads to destruction of more than one polypeptide, by measuring polypeptide remaining. The target inactivation analysis studies indicate that heart and skeletal muscle receptors are structurally very similar.

  1. Correction of Multiple Striated Muscles in Murine Pompe Disease Through Adeno-associated Virus-Mediated Gene Therapy

    PubMed Central

    Sun, Baodong; Young, Sarah P.; Li, Ping; Di, Chunhui; Brown, Talmage; Salva, Maia Z.; Li, Songtao; Bird, Andrew; Yan, Zhen; Auten, Richard; Hauschka, Stephen D.; Koeberl, Dwight D.

    2009-01-01

    Glycogen storage disease type II (GSD-II; Pompe disease; MIM 232300) stems from the deficiency of acid-α-glucosidase (GAA; acid maltase; EC 3.2.1.20), which primarily involves cardiac and skeletal muscles. We hypothesized that systemic administration of an adeno-associated virus (AAV) vector containing a muscle specific regulatory cassette could drive efficacious transgene expression in GAA-knockout (GAA-KO) mice. AAV2/8 vectors containing the muscle creatine kinase (CK1) or hybrid α-myosin heavy chain enhancer-/muscle creatine kinase enhancer-promoter (MHCK7) cassettes were compared. The CK1 reduced glycogen content by approximately 50% in the heart and quadriceps, in comparison to untreated GAA-KO mice, whereas the MHCK7 containing vector reduced glycogen content even further: >95% in heart and >75% in the diaphragm and quadriceps. Administration of the MHCK7-containing vector significantly increased striated muscle function as assessed by increased Rotarod times at 18 weeks post-injection, whereas the CK1-containing vector did not increase Rotarod performance. Transduction efficiency was evaluated with an AAV2/8 vector in which MHCK7 drives alkaline-phosphatase, revealing that many more myofibers were transduced in the quadriceps than in the gastrocnemius. An AAV2/9 vector containing the MHCK7 cassette corrected GAA deficiency in the skeletal muscles of the distal limb, including the gastrocnemius, extensor digitalis longus, and soleus; furthermore, glycogen accumulations were substantially cleared by hGAA expression therein. Importantly, type IIb myofibers in the extensor digitalis longus were transduced, thereby correcting a myofiber type that is unresponsive to enzyme replacement therapy. In summary, AAV8 and AAV9-pseudotyped vectors containing the MHCK7 regulatory cassette achieved enhanced efficacy in Pompe disease mice. PMID:18560415

  2. Correction of multiple striated muscles in murine Pompe disease through adeno-associated virus-mediated gene therapy.

    PubMed

    Sun, Baodong; Young, Sarah P; Li, Ping; Di, Chunhui; Brown, Talmage; Salva, Maja Z; Li, Songtao; Bird, Andrew; Yan, Zhen; Auten, Richard; Hauschka, Stephen D; Koeberl, Dwight D

    2008-08-01

    Glycogen storage disease type II (Pompe disease; MIM 232300) stems from the deficiency of acid alpha-glucosidase (GAA; acid maltase; EC 3.2.1.20), which primarily involves cardiac and skeletal muscles. An adeno-associated virus 2/8 (AAV2/8) vector containing the muscle creatine kinase (MCK) (CK1) reduced glycogen content by approximately 50% in the heart and quadriceps in GAA-knockout (GAA-KO) mice; furthermore, an AAV2/8 vector containing the hybrid alpha-myosin heavy chain enhancer-/MCK enhancer-promoter (MHCK7) cassette reduced glycogen content by >95% in heart and >75% in the diaphragm and quadriceps. Transduction with an AAV2/8 vector was higher in the quadriceps than in the gastrocnemius. An AAV2/9 vector containing the MHCK7 cassette corrected GAA deficiency in the distal hindlimb, and glycogen accumulations were substantially cleared by human GAA (hGAA) expression therein; however, the analogous AAV2/7 vector achieved much lower efficacy. Administration of the MHCK7-containing vectors significantly increased striated muscle function as assessed by increased Rotarod times at 18 weeks after injection, whereas the CK1-containing vector did not increase Rotarod performance. Importantly, type IIb myofibers in the extensor digitalis longus (EDL) were transduced, thereby correcting a myofiber type that is unresponsive to enzyme replacement therapy. In summary, AAV8 and AAV9-pseudotyped vectors containing the MHCK7 regulatory cassette achieved enhanced efficacy in Pompe disease mice. PMID:18560415

  3. (-)-Epicatechin improves mitochondrial-related protein levels and ameliorates oxidative stress in dystrophic δ-sarcoglycan null mouse striated muscle.

    PubMed

    Ramirez-Sanchez, Israel; De los Santos, Sergio; Gonzalez-Basurto, Silvia; Canto, Patricia; Mendoza-Lorenzo, Patricia; Palma-Flores, Carlos; Ceballos-Reyes, Guillermo; Villarreal, Francisco; Zentella-Dehesa, Alejandro; Coral-Vazquez, Ramon

    2014-12-01

    Muscular dystrophies (MDs) are a group of heterogeneous genetic disorders characterized by progressive striated muscle wasting and degeneration. Although the genetic basis for many of these disorders has been identified, the exact mechanism of disease pathogenesis remains unclear. The presence of oxidative stress (OS) is known to contribute to the pathophysiology and severity of the MD. Mitochondrial dysfunction is observed in MD, and probably represents an important determinant of increased OS. Experimental antioxidant therapies have been implemented with the aim of protecting against disease progression, but results from clinical trials have been disappointing. In this study, we explored the capacity of the cacao flavonoid (-)-epicatechin (Epi) to mitigate OS by acting as a positive regulator of mitochondrial structure/function endpoints and redox balance control systems in skeletal and cardiac muscles of dystrophic, δ-sarcoglycan (δ-SG) null mice. Wild-type or δ-SG null 2.5-month-old male mice were treated via oral gavage with either water (controls) or Epi (1 mg·kg(-1) , twice daily) for 2 weeks. The results showed significant normalization of total protein carbonylation, recovery of the glutathione/oxidized glutathione ratio and enhanced superoxide dismutase 2, catalase and citrate synthase activities with Epi treatment. These effects were accompanied by increases in the protein levels of thioredoxin, glutathione peroxidase, superoxide dismutase 2, catalase, and mitochondrial endpoints. Furthermore, we found decreases in heart and skeletal muscle fibrosis, accompanied by an improvement in skeletal muscle function, with treatment. These results warrant further investigation of Epi as a potential therapeutic agent to mitigate MD-associated muscle degeneration. PMID:25284161

  4. (−)-EPICATECHIN IMPROVES MITOCHONDRIAL RELATED PROTEIN LEVELS AND AMELIORATES OXIDATIVE STRESS IN DYSTROPHIC DELTA SARCOGLYCAN NULL MOUSE STRIATED MUSCLE

    PubMed Central

    Ramirez-Sanchez, Israel; De los Santos, Sergio; Gonzalez-Basurto, Silvia; Canto, Patricia; Mendoza-Lorenzo, Patricia; Palma-Flores, Carlos; Ceballos-Reyes, Guillermo; Villarreal, Francisco; Zentella-Dehesa, Alejandro; Coral-Vazquez, Ramon

    2014-01-01

    Muscular dystrophies (MD) are a group of heterogeneous genetic disorders characterized by progressive striated muscle wasting and degeneration. Although the genetic basis for many of these disorders has been identified, the exact mechanism for disease pathogenesis remains unclear. The presence of oxidative stress (OS) is known to contribute to the pathophysiology and severity of the MD. Mitochondrial dysfunction is observed in MD and likely represents an important determinant of increased OS. Experimental antioxidant therapies have been implemented with the aim of protecting against disease progression, but results from clinical trials have been disappointing. In this study, we explored the capacity of the cacao flavonoid (−)-epicatechin (Epi) to mitigate OS by acting as a positive regulator of mitochondrial structure/function endpoints and redox balance control systems in skeletal and cardiac muscles of dystrophic, δ-sarcoglycan (δ-SG) null mice. Wild type or δ-SG null 2.5 month old male mice were treated via oral gavage with either water (control animals) or Epi (1 mg/kg, twice/day) for 2 weeks. Results evidence a significant normalization of total protein carbonylation, recovery of reduced/oxidized glutathione (GSH/GSSG ratio) and enhanced superoxide dismutase 2, catalase and citrate synthase activities with Epi treatment. These effects were accompanied by increases in protein levels for thiolredoxin, glutathione peroxidase, superoxide dismutase 2, catalase and mitochondrial endpoints. Furthermore, we evidence decreases in heart and skeletal muscle fibrosis, accompanied with an improvement in skeletal muscle function with treatment. These results warrant the further investigation of Epi as a potential therapeutic agent to mitigate MD associated muscle degeneration. PMID:25284161

  5. Study of the function of sarcoplasmic reticulum of vascular smooth muscle during activation due to depolarization-induced calcium influx

    SciTech Connect

    Hwang, K.S.

    1987-01-01

    The role of sarcoplasmic reticulum (SR) in vascular smooth muscle was evaluated with respect to regulation of myoplasmic Ca{sup 2+} during the Ca{sup 2+} entry induced by depolarization. Calcium agonist, Bay K8644, stimulated Ca{sup 2+} influx as well as tension in physiological salt solution, (PSS) in contrast to the priming effects due to the depolarization originally reported. Disparity, however, was found between the Ca{sup 2+} entered and tension developed. Correlation between the tension and {sup 45}Ca influx showed a typical threshold phenomenon; the basal Ca{sup 2+} influx can be raised to a certain level (25%) without tension induction, after which a minor increase in Ca{sup 2+} influx produced significant tension. This subthreshold Ca{sup 2+} influx was found accumulated in the caffeine-sensitive Ca stores, the SR. This confirmed the dependency of tension on the rate of Ca{sup 2+} entry demonstrated by a previous report.

  6. Dietary fish oil blocks the microcirculatory manifestations of ischemia-reperfusion injury in striated muscle in hamsters.

    PubMed Central

    Lehr, H A; Hübner, C; Nolte, D; Kohlschütter, A; Messmer, K

    1991-01-01

    Epidemiologic observations and experimental studies have demonstrated a protective effect of dietary fish oil on the clinical manifestations of ischemia-reperfusion injury. To investigate the underlying mechanisms, we used the dorsal skinfold chamber model for intravital fluorescence microscopy of the microcirculation in striated muscle of awake hamsters. In control hamsters (n = 7), reperfusion after a 4-hr pressure-induced ischemia to the muscle tissue elicited the adhesion of fluorescently stained leukocytes to the endothelium of postcapillary venules, capillary obstruction, and the break-down of endothelial integrity. These microvascular manifestations of ischemia-reperfusion injury were significantly attenuated in animals (n = 7) when fed with a fish oil-enriched diet for 4 weeks prior to the experiments. In leukocyte total lipids, the fish oil diet resulted in a substantial displacement of arachidonic acid, the precursor of the potent adhesion-promoting leukotriene (LT) B4, by fish oil-derived eicosapentaenoic acid, the precursor of biologically less potent LTB5, emphasizing the mediator role of LTB4 in ischemia-reperfusion injury. These results suggest that the preservation of microvascular perfusion by dietary fish oil contributes to its protective effects on the clinical manifestations of ischemia-reperfusion injury. PMID:1650479

  7. The “Goldilocks Zone” from a redox perspective—Adaptive vs. deleterious responses to oxidative stress in striated muscle

    PubMed Central

    Alleman, Rick J.; Katunga, Lalage A.; Nelson, Margaret A. M.; Brown, David A.; Anderson, Ethan J.

    2014-01-01

    Consequences of oxidative stress may be beneficial or detrimental in physiological systems. An organ system's position on the “hormetic curve” is governed by the source and temporality of reactive oxygen species (ROS) production, proximity of ROS to moieties most susceptible to damage, and the capacity of the endogenous cellular ROS scavenging mechanisms. Most importantly, the resilience of the tissue (the capacity to recover from damage) is a decisive factor, and this is reflected in the disparate response to ROS in cardiac and skeletal muscle. In myocytes, a high oxidative capacity invariably results in a significant ROS burden which in homeostasis, is rapidly neutralized by the robust antioxidant network. The up-regulation of key pathways in the antioxidant network is a central component of the hormetic response to ROS. Despite such adaptations, persistent oxidative stress over an extended time-frame (e.g., months to years) inevitably leads to cumulative damages, maladaptation and ultimately the pathogenesis of chronic diseases. Indeed, persistent oxidative stress in heart and skeletal muscle has been repeatedly demonstrated to have causal roles in the etiology of heart disease and insulin resistance, respectively. Deciphering the mechanisms that underlie the divergence between adaptive and maladaptive responses to oxidative stress remains an active area of research for basic scientists and clinicians alike, as this would undoubtedly lead to novel therapeutic approaches. Here, we provide an overview of major types of ROS in striated muscle and the divergent adaptations that occur in response to them. Emphasis is placed on highlighting newly uncovered areas of research on this topic, with particular focus on the mitochondria, and the diverging roles that ROS play in muscle health (e.g., exercise or preconditioning) and disease (e.g., cardiomyopathy, ischemia, metabolic syndrome). PMID:25278906

  8. [Ultrastructural changes in transverse striated muscles under the influence of space flight factors].

    PubMed

    Pozdniakov, O M; Babakova, L L; Demorzhi, M S

    1988-12-01

    The influence of space flight (on the biosatellite "Kosmos-1667") on muscles (diaphragmatic, soleus, gastrocnemius) was studied by electron microscope. Muscles had destructive and atrophic changes. The rate of changes was maximal in m. soleus, minimal in the diaphragmatic m. However, some regeneration was found demonstrating the reversibility of changes. PMID:2974735

  9. Alterations in mitochondria and sarcoplasmic reticulum from heart and skeletal muscle of horizontally casted primates

    NASA Technical Reports Server (NTRS)

    Sordahl, L. A.; Stone, H. L.

    1982-01-01

    Horizontally body-casted rhesus monkeys are used as an animal model in order to study the physiological changes known as cardiovascular deconditioning which occur during weightless conditions. No difference was found between the experimental and control animals in heart mitochondrial oxidative phosphorylation which indicates that no apparent changes occurred in the primary energy-producing system of the heart. A marked increase in cytochrome oxidase activity was observed in the casted primate heart mitochondria compared to controls, while a 25% decrease in respiratory substrate-supported calcium uptake was found in casted primate heart mitochondria compared to controls. Sacroplasmic reticulum isolated from the primate hearts revealed marked changes in calcium transport activities. It is concluded that the marked depression in cardiac sarcoplasmic reticulum functions indicates altered calcium homeostasis in the casted-primate heart which could be a factor in cardiovascular deconditioning.

  10. Development of Trichosomoides nasalis (Nematoda: Trichinelloidea) in the murid host: evidence for larval growth in striated muscle fibres

    PubMed Central

    Fall, E.H.; Diagne, M.; Junker, K.; Duplantier, J.M.; Ba, K.; Vallée, I.; Bain, O.

    2012-01-01

    Trichosomoides nasalis (Trichinelloidea) is a parasite of Arvicanthis niloticus (Muridae) in Senegal. Female worms that harbour dwarf males in their uteri, occur in the epithelium of the nasal mucosa. Young laboratory-bred A. niloticus were either fed females containing larvated eggs or intraperitoneally injected with motile first-stage larvae recovered from female uteri. Both resulted in successful infection. Organs examined during rodent necropsy were blood and lymphatic circulatory systems (heart, large vessels, lymphnodes), lungs, liver, kidneys, thoracic and abdominal cavities, thoracic and abdominal muscular walls, diaphragm, tongue, and nasal mucosa. Development to adult nasal stages took three weeks. Recovery of newly hatched larvae from the peritoneal fluid at four-eight hours after oral infection suggests a direct passage from the stomach or intestinal wall to the musculature. However, dissemination through the blood, as observed with Trichinella spiralis, cannot be excluded even though newly hatched larvae of T. nasalis are twice as thick (15 μm). Developing larvae were found in histological sections of the striated muscle of the abdominal and thoracic walls, and larvae in fourth moult were dissected from these sites. Adult females were found in the deep nasal mucosa where mating occurred prior to worms settling in the nasal epithelium. The present study shows a remarkable similarity between T. nasalis and Trichinella species regarding muscle tropism, but the development of T. nasalis is not arrested at the late first-larval stage and does not induce transformation of infected fibres into nurse cells. T. nasalis seems a potential model to study molecular relations between trichinelloid larvae and infected muscle fibres. PMID:22314237

  11. Triclosan impairs excitation-contraction coupling and Ca2+ dynamics in striated muscle.

    PubMed

    Cherednichenko, Gennady; Zhang, Rui; Bannister, Roger A; Timofeyev, Valeriy; Li, Ning; Fritsch, Erika B; Feng, Wei; Barrientos, Genaro C; Schebb, Nils H; Hammock, Bruce D; Beam, Kurt G; Chiamvimonvat, Nipavan; Pessah, Isaac N

    2012-08-28

    Triclosan (TCS), a high-production-volume chemical used as a bactericide in personal care products, is a priority pollutant of growing concern to human and environmental health. TCS is capable of altering the activity of type 1 ryanodine receptor (RyR1), but its potential to influence physiological excitation-contraction coupling (ECC) and muscle function has not been investigated. Here, we report that TCS impairs ECC of both cardiac and skeletal muscle in vitro and in vivo. TCS acutely depresses hemodynamics and grip strength in mice at doses ≥12.5 mg/kg i.p., and a concentration ≥0.52 μM in water compromises swimming performance in larval fathead minnow. In isolated ventricular cardiomyocytes, skeletal myotubes, and adult flexor digitorum brevis fibers TCS depresses electrically evoked ECC within ∼10-20 min. In myotubes, nanomolar to low micromolar TCS initially potentiates electrically evoked Ca(2+) transients followed by complete failure of ECC, independent of Ca(2+) store depletion or block of RyR1 channels. TCS also completely blocks excitation-coupled Ca(2+) entry. Voltage clamp experiments showed that TCS partially inhibits L-type Ca(2+) currents of cardiac and skeletal muscle, and [(3)H]PN200 binding to skeletal membranes is noncompetitively inhibited by TCS in the same concentration range that enhances [(3)H]ryanodine binding. TCS potently impairs orthograde and retrograde signaling between L-type Ca(2+) and RyR channels in skeletal muscle, and L-type Ca(2+) entry in cardiac muscle, revealing a mechanism by which TCS weakens cardiac and skeletal muscle contractility in a manner that may negatively impact muscle health, especially in susceptible populations. PMID:22891308

  12. Skeletal Muscle Myofibrillar and Sarcoplasmic Protein Synthesis Rates Are Affected Differently by Altitude-Induced Hypoxia in Native Lowlanders

    PubMed Central

    Holm, Lars; Haslund, Mads Lyhne; Robach, Paul; van Hall, Gerrit; Calbet, Jose A. L.; Saltin, Bengt; Lundby, Carsten

    2010-01-01

    As a consequence to hypobaric hypoxic exposure skeletal muscle atrophy is often reported. The underlying mechanism has been suggested to involve a decrease in protein synthesis in order to conserve O2. With the aim to challenge this hypothesis, we applied a primed, constant infusion of 1-13C-leucine in nine healthy male subjects at sea level and subsequently at high-altitude (4559 m) after 7–9 days of acclimatization. Physical activity levels and food and energy intake were controlled prior to the two experimental conditions with the aim to standardize these confounding factors. Blood samples and expired breath samples were collected hourly during the 4 hour trial and vastus lateralis muscle biopsies obtained at 1 and 4 hours after tracer priming in the overnight fasted state. Myofibrillar protein synthesis rate was doubled; 0.041±0.018 at sea-level to 0.080±0.018%⋅hr−1 (p<0.05) when acclimatized to high altitude. The sarcoplasmic protein synthesis rate was in contrast unaffected by altitude exposure; 0.052±0.019 at sea-level to 0.059±0.010%⋅hr−1 (p>0.05). Trends to increments in whole body protein kinetics were seen: Degradation rate elevated from 2.51±0.21 at sea level to 2.73±0.13 µmol⋅kg−1⋅min−1 (p = 0.05) at high altitude and synthesis rate similar; 2.24±0.20 at sea level and 2.43±0.13 µmol⋅kg−1⋅min−1 (p>0.05) at altitude. We conclude that whole body amino acid flux is increased due to an elevated protein turnover rate. Resting skeletal muscle myocontractile protein synthesis rate was concomitantly elevated by high-altitude induced hypoxia, whereas the sarcoplasmic protein synthesis rate was unaffected by hypoxia. These changed responses may lead to divergent adaptation over the course of prolonged exposure. PMID:21187972

  13. Androgens enhance in vivo 2-deoxyglucose uptake by rat striated muscle

    NASA Technical Reports Server (NTRS)

    Max, S. R.; Toop, J.

    1983-01-01

    It is shown that testosterone propionate (TP) causes a striking increase in the in vivo uptake of 2-deoxyglucose (2-DG) by the levator ani muscle of immature male rats, which was found to be uniformly distributed over the entire muscle. After a single subcutaneous injection of TP, no enhancement of 2-DG was observed before 3.5 hr, at which time uptake was increased 2-fold; maximum enhancement (4-fold) was attained at 12 hr. At 72 hr, 2-DG uptake remained elevated at twice the control value. It was determined that the effect of TP probably is mediated by specific androgen receptors. In addition, it was found that the effect of TP was blocked by the simultaneous administration of an androgen antagonist, cyproterone acetate. TP also was found to enhance the uptake of 2-DG in the bulbocavernosus (253 percent over control) and extensor digitorum longus muscles (150 percent over control), but not in the biceps brachii or soleus. It is suggested that the increased uptake of glucose may be an important early step in the anabolic response of muscle to androgens.

  14. Effects of different activity and inactivity paradigms on myosin heavy chain gene expression in striated muscle

    NASA Technical Reports Server (NTRS)

    Baldwin, K. M.; Haddad, F.

    2001-01-01

    The goal of this mini-review is to summarize findings concerning the role that different models of muscular activity and inactivity play in altering gene expression of the myosin heavy chain (MHC) family of motor proteins in mammalian cardiac and skeletal muscle. This was done in the context of examining parallel findings concerning the role that thyroid hormone (T(3), 3,5,3'-triiodothyronine) plays in MHC expression. Findings show that both cardiac and skeletal muscles of experimental animals are initially undifferentiated at birth and then undergo a marked level of growth and differentiation in attaining the adult MHC phenotype in a T(3)/activity level-dependent fashion. Cardiac MHC expression in small mammals is highly sensitive to thyroid deficiency, diabetes, energy deprivation, and hypertension; each of these interventions induces upregulation of the beta-MHC isoform, which functions to economize circulatory function in the face of altered energy demand. In skeletal muscle, hyperthyroidism, as well as interventions that unload or reduce the weight-bearing activity of the muscle, causes slow to fast MHC conversions. Fast to slow conversions, however, are seen under hypothyroidism or when the muscles either become chronically overloaded or subjected to intermittent loading as occurs during resistance training and endurance exercise. The regulation of MHC gene expression by T(3) or mechanical stimuli appears to be strongly regulated by transcriptional events, based on recent findings on transgenic models and animals transfected with promoter-reporter constructs. However, the mechanisms by which T(3) and mechanical stimuli exert their control on transcriptional processes appear to be different. Additional findings show that individual skeletal muscle fibers have the genetic machinery to express simultaneously all of the adult MHCs, e.g., slow type I and fast IIa, IIx, and IIb, in unique combinations under certain experimental conditions. This degree of

  15. The toxic effect of R350P mutant desmin in striated muscle of man and mouse.

    PubMed

    Clemen, Christoph S; Stöckigt, Florian; Strucksberg, Karl-Heinz; Chevessier, Frederic; Winter, Lilli; Schütz, Johanna; Bauer, Ralf; Thorweihe, José-Manuel; Wenzel, Daniela; Schlötzer-Schrehardt, Ursula; Rasche, Volker; Krsmanovic, Pavle; Katus, Hugo A; Rottbauer, Wolfgang; Just, Steffen; Müller, Oliver J; Friedrich, Oliver; Meyer, Rainer; Herrmann, Harald; Schrickel, Jan Wilko; Schröder, Rolf

    2015-02-01

    Mutations of the human desmin gene on chromosome 2q35 cause autosomal dominant, autosomal recessive and sporadic forms of protein aggregation myopathies and cardiomyopathies. We generated R349P desmin knock-in mice, which harbor the ortholog of the most frequently occurring human desmin missense mutation R350P. These mice develop age-dependent desmin-positive protein aggregation pathology, skeletal muscle weakness, dilated cardiomyopathy, as well as cardiac arrhythmias and conduction defects. For the first time, we report the expression level and subcellular distribution of mutant versus wild-type desmin in our mouse model as well as in skeletal muscle specimens derived from human R350P desminopathies. Furthermore, we demonstrate that the missense-mutant desmin inflicts changes of the subcellular localization and turnover of desmin itself and of direct desmin-binding partners. Our findings unveil a novel principle of pathogenesis, in which not the presence of protein aggregates, but disruption of the extrasarcomeric intermediate filament network leads to increased mechanical vulnerability of muscle fibers. These structural defects elicited at the myofiber level finally impact the entire organ and subsequently cause myopathy and cardiomyopathy. PMID:25394388

  16. Solubilization and characterization of a ouabain-sensitive protein from transverse tubule membrane-junctional sarcoplasmic reticulum complexes (TTM-JSR) in cat cardiac muscle.

    PubMed

    Fujino, S; Satoh, K; Bando, T; Kurokawa, T; Nakai, T; Takashima, K; Fujino, M

    1989-05-15

    A new glycoprotein of 31,500 dalton, which has a high affinity for ouabain, and is independent of (Na+-K+)-ATPase, was solubilized from transverse tubule membrane and junctional sarcoplasmic reticulum complexes (TTM-JSR) of cat cardiac muscle. This protein could be extracted only in small amounts from sarcolemma-plasma membrane (SLM-PL) fragments, suggesting that it indeed originates from the TTM-JSR. PMID:2721638

  17. Thermal dependence of force-velocity relation of lamprey live striated muscle fibres.

    PubMed

    Sobol, C V; Nasledov, G A

    1994-06-01

    The thermal dependence of the force-velocity relation (P - V) in thin (20-40 fibres) live twitch muscle bundles from suction apparatus of lamprey by force-clamp method was investigated. The P - V relation was hyperbolic and Hill's constants were as follows: a/P0 was 0.13 +/- 0.01 and 0.08 +/- 0.01 (mean +/- S.E.M.), b was 0.46 +/- 0.02 and 0.65 +/- 0.03 at 8 degrees C and 18 degrees C, respectively. The maximal isometric tension (P0) was about 100 mN/mm2 at 8 degrees C, 18 degrees C, and 22 degrees C. After the temperature was switched from 8 degrees C to 18 degrees C, the dependence of P0 on incubation time was observed. The maximal power output determined from P - V relation using Hill's equation was 0.062 +/- 0.002 and 0.056 +/- 0.001 at 8 degrees C and 18 degrees C, respectively. The maximal velocities of shortening (V0) were 3.9 +/- 0.1 L0/s and 7.2 +/- 0.2 L0/s at 8 degrees C and 18 degrees C, respectively. Q10 for V0 in this range of temperatures was 1.86. a/P0 and power output were about 2 times lower than those reported in literature for other animals. In general, the thermal dependence of the parameters studied was similar to those reported for fish muscles and skinned lamprey muscles, P0 being relatively independent, V0 highly dependent, and a/P0 inversely dependent on temperature. PMID:7835682

  18. The formation and regression of synapses during the re-innervation of axolotl striated muscles.

    PubMed Central

    Bennett, M R; Raftos, J

    1977-01-01

    1. A study has been made of the formation and regression of synapses formed by spinal nerves 16 and 17 in axolotl hind-limb flexor muscles following the severing of nerve 16, using histological, ultrastructural and electrophysiological techniques. 2. Axolotl hind-limb flexor myofibres possessed 'en plaque' end-plates from either spinal nerve 16 or 17 or both at intervals of about 1000 micronm along their length; the myofibre's length constant was about 700 micronm allowing electrophysiological observations of at least two of these synapses during a single impalement; transmitter release at these synapses could be described by binomial statistics and in a given set of ionic conditions the binomial statistic parameter n was directly proportional to the size of the nerve terminals whilst the binomial statistic parameter p was invariant to changes in nerve terminal size. 3. The distribution of synapses formed by spinal nerves 16 and 17 in different sectors of the axolotl hind-limb flexor muscles was determined from a study of evoked end-plate potentials; the middle and proximal sectors of the flexor muscles contained myofibres which received an innervation from nerve 16 only, whereas the sectors surrounding these contained myofibres innervated either by nerve 16 or nerve 17 or by both nerves. 4. Six days following the severing of spinal nerve 16, evoked transmitter release from the synapses formed by this nerve had failed; transmission was subsequently recorded at a few synapses formed by nerve 17 in the middle and proximal sectors of the flexor muscles which are not normally innervated by this nerve and these synapses had a low n; during the succeeding four weeks the value of n at the synapses increased to a size about 70% that of the terminals normally formed by nerve 16 at these sites. 5. Four weeks after severing nerve 16, myofibres which possessed synapses formed by nerve 17 also possessed synapses from re-innervating nerve 16 and these were sometimes formed at

  19. Metabolic consequences of functional complexes of mitochondria, myofibrils and sarcoplasmic reticulum in muscle cells.

    PubMed

    Andrienko, T; Kuznetsov, A V; Kaambre, T; Usson, Y; Orosco, A; Appaix, F; Tiivel, T; Sikk, P; Vendelin, M; Margreiter, R; Saks, V A

    2003-06-01

    Regulation of mitochondrial respiration both by endogenous and exogenous ADP in the cells in situ was studied in isolated and permeabilized cardiomyocytes, permeabilized cardiac fibers and 'ghost' fibers (all with a diameter of 10-20 micro m) at different (0-3 micro moll(-1)) free Ca(2+) concentrations in the medium. In all these preparations, the apparent K(m) of mitochondrial respiration for exogenous ADP at free Ca(2+) concentrations of 0-0.1 micro moll(-1) was very high, in the range of 250-350 micro moll(-1), in contrast to isolated mitochondria in vitro (apparent K(m) for ADP is approximately 20 micro moll(-1)). An increase in the free Ca(2+) concentration (up to 3 micro moll(-1), which is within physiological range), resulted in a very significant decrease of the apparent K(m) value to 20-30 micro moll(-1), a decrease of V(max) of respiration in permeabilized intact fibers and a strong contraction of sarcomeres. In ghost cardiac fibers, from which myosin was extracted but mitochondria were intact, neither the high apparent K(m) for ADP (300-350 micro moll(-1)) nor V(max) of respiration changed in the range of free Ca(2+) concentration studied, and no sarcomere contraction was observed. The exogenous-ADP-trapping system (pyruvate kinase + phosphoenolpyruvate) inhibited endogenous-ADP-supported respiration in permeabilized cells by no more than 40%, and this inhibition was reversed by creatine due to activation of mitochondrial creatine kinase. These results are taken to show strong structural associations (functional complexes) among mitochondria, sarcomeres and sarcoplasmic reticulum. Inside these complexes, mitochondrial functional state is controlled by channeling of ADP, mostly via energy- and phosphoryl-transfer networks, and apparently depends on the state of sarcomere structures. PMID:12756288

  20. Modulation of the cytosolic androgen receptor in striated muscle by sex steroids

    NASA Technical Reports Server (NTRS)

    Rance, N. E.; Max, S. R.

    1984-01-01

    The effects of orchiectomy (GDX) and of subsequent administration of testosterone propionate (TP) or 17(beta)-estradiol (E2) on the maximum binding (Bmax) and apparent Kd of the cytosolic androgen receptor in levator ani (LA) and skeletal muscles of adult male Sprague-Dawley rats are investigated experimentally. The results are presented in graphs and discussed. In LA, BMAX is found to rise from a control level of 2.5 fmol/mg protein to 280, 600, 478, and 133 percent of control at 12 h, 14 d, 30 d, and 44 d after GDX, respectively, while Kd increased only insignificantly (from 680 to 960 fM); Bmax is held at control levels for 6 h by cycloheximide given at GDX, is unaffected by TP given at 30 d, and is further increased (by 480 percent at 44 d) by administration of E2 at 30 d. Bmax in skeletal muscles is found to increase to 139, 212, 220, and 158 percent of control at 12 h, 14 d, 30 d, and 44 d, respectively; Bmax is returned to control at 44 d by TP at 30 d but is not affected by E2. The effect of E2 in LA is attributed to either induction of the cytosolic receptor or a decreased rate of receptor degradation.

  1. In vitro and in vivo single myosin step-sizes in striated muscle.

    PubMed

    Burghardt, Thomas P; Sun, Xiaojing; Wang, Yihua; Ajtai, Katalin

    2015-12-01

    Myosin in muscle transduces ATP free energy into the mechanical work of moving actin. It has a motor domain transducer containing ATP and actin binding sites, and, mechanical elements coupling motor impulse to the myosin filament backbone providing transduction/mechanical-coupling. The mechanical coupler is a lever-arm stabilized by bound essential and regulatory light chains. The lever-arm rotates cyclically to impel bound filamentous actin. Linear actin displacement due to lever-arm rotation is the myosin step-size. A high-throughput quantum dot labeled actin in vitro motility assay (Qdot assay) measures motor step-size in the context of an ensemble of actomyosin interactions. The ensemble context imposes a constant velocity constraint for myosins interacting with one actin filament. In a cardiac myosin producing multiple step-sizes, a "second characterization" is step-frequency that adjusts longer step-size to lower frequency maintaining a linear actin velocity identical to that from a shorter step-size and higher frequency actomyosin cycle. The step-frequency characteristic involves and integrates myosin enzyme kinetics, mechanical strain, and other ensemble affected characteristics. The high-throughput Qdot assay suits a new paradigm calling for wide surveillance of the vast number of disease or aging relevant myosin isoforms that contrasts with the alternative model calling for exhaustive research on a tiny subset myosin forms. The zebrafish embryo assay (Z assay) performs single myosin step-size and step-frequency assaying in vivo combining single myosin mechanical and whole muscle physiological characterizations in one model organism. The Qdot and Z assays cover "bottom-up" and "top-down" assaying of myosin characteristics. PMID:26728749

  2. Drug action of benzocaine on the sarcoplasmic reticulum Ca-ATPase from fast-twitch skeletal muscle.

    PubMed

    Di Croce, D; Trinks, P W; Grifo, M B; Takara, D; Sánchez, G A

    2015-11-01

    The effect of the local anesthetic benzocaine on sarcoplasmic reticulum membranes isolated from fast-twitch muscles was tested. The effects on Ca-ATPase activity, calcium binding and uptake, phosphoenzyme accumulation and decomposition were assessed using radioisotopic methods. The calcium binding to the Ca-ATPase was noncompetitively inhibited, and the enzymatic activity decreased in a concentration-dependent manner (IC50 47.1 mM). The inhibition of the activity depended on the presence of the calcium ionophore calcimycin and the membrane protein concentration. The pre-exposure of the membranes to benzocaine enhanced the enzymatic activity in the absence of calcimycin, supporting the benzocaine permeabilizing effect, which was prevented by calcium. Benzocaine also interfered with the calcium transport capability by decreasing the maximal uptake (IC50 40.3 mM) without modification of the calcium affinity for the ATPase. It inhibited the phosphorylation of the enzyme, and at high benzocaine concentration, the dephosphorylation step became rate-limiting as suggested by the biphasic profile of phosphoenzyme accumulation at different benzocaine concentrations. The data reported in this paper revealed a complex pattern of inhibition involving two sites for interaction with low and high benzocaine concentrations. It is concluded that benzocaine not only exerts an indirect action on the membrane permeability to calcium but also affects key steps of the Ca-ATPase enzymatic cycle. PMID:26173386

  3. Structure and interactions of the carboxyl terminus of striated muscle alpha-tropomyosin: it is important to be flexible.

    PubMed Central

    Greenfield, Norma J; Palm, Thomas; Hitchcock-DeGregori, Sarah E

    2002-01-01

    Tropomyosin (TM) binds to and regulates the actin filament. We used circular dichroism and heteronuclear NMR to investigate the secondary structure and interactions of the C terminus of striated muscle alpha-TM, a major functional determinant, using a model peptide, TM9a(251-284). The (1)H(alpha) and (13)C(alpha) chemical shift displacements show that residues 252 to 277 are alpha-helical but residues 278 to 284 are nonhelical and mobile. The (1)H(N) and (13)C' displacements suggest that residues 257 to 269 form a coiled coil. Formation of an "overlap" binary complex with a 33-residue N-terminal chimeric peptide containing residues 1 to 14 of alpha-TM perturbs the (1)H(N) and (15)N resonances of residues 274 to 284. Addition of a fragment of troponin T, TnT(70-170), to the binary complex perturbs most of the (1)H(N)-(15)N cross-peaks. In addition, there are many new cross-peaks, showing that the binding is asymmetric. Q263, in a proposed troponin T binding site, shows two sets of side-chain (15)N-(1)H cross-peaks, indicating conformational flexibility. The conformational equilibrium of the side chain changes upon formation of the binary and ternary complexes. Replacing Q263 with leucine greatly increases the stability of TM9a(251-284) and reduces its ability to form the binary and ternary complexes, showing that conformational flexibility is crucial for the binding functions of the C terminus. PMID:12414708

  4. Localization of the N-terminal and C-terminal ends of triadin with respect to the sarcoplasmic reticulum membrane of rabbit skeletal muscle.

    PubMed Central

    Marty, I; Robert, M; Ronjat, M; Bally, I; Arlaud, G; Villaz, M

    1995-01-01

    Antibodies were raised against synthetic peptides corresponding to the N-terminal (residues 2-17) and C-terminal (residues 691-706) ends of rabbit skeletal muscle triadin, a 95 kDa protein located in the sarcoplasmic reticulum membrane at the triad junction. The specificity of the antibodies generated was tested by ELISA and Western blot analysis. These tests demonstrated the ability of the antibodies to react specifically with the proteins. The anti-N-terminus antibodies bound to sarcoplasmic reticulum vesicles, indicating that the N-terminal end of the membrane-embedded triadin is exposed on the cytoplasmic side of the vesicles. In contrast, the anti-C-terminus antibodies were able to react with sarcoplasmic reticulum vesicles only after permeabilization of the vesicles with a detergent, indicating that the C-terminal end is exposed on the luminal side of the vesicles. These immunological data were complemented by proteolysis experiments using carboxypeptidases and endoproteinase Arg C. A mixture of carboxypeptidases A, B and Y was used to induce degradation of the C-terminal end of triadin in sarcoplasmic reticulum vesicles. This degradation, and a concomitant loss of reactivity of the anti-C-terminus antibodies in Western blots, was observed only when the vesicles were permeabilized, providing further evidence for the luminal localization of the C-terminal end of triadin. Treatment of sarcoplasmic reticulum vesicles with endoproteinase Arg C resulted in the removal of the N-terminal end of triadin, probably due to cleavage after Arg-34. This is a further indication of the cytoplasmic localization of the N-terminal end of triadin (and of its first 34 amino acids). When the proteolysis with endoproteinase Arg C was carried out with permeabilized vesicles, the cleavage occurred after Arg-141 or Arg-157, indicating that at least one of these residues is luminal. Images Figure 2 Figure 4 Figure 5 Figure 6 PMID:7741707

  5. Effects of Mg2+ on Ca2+ release from sarcoplasmic reticulum of skeletal muscle fibres from yabby (crustacean) and rat.

    PubMed

    Launikonis, B S; Stephenson, D G

    2000-07-15

    1. The role of myoplasmic [Mg2+] on Ca2+ release from the sarcoplasmic reticulum (SR) was examined in the two major types of crustacean muscle fibres, the tonic, long sarcomere fibres and the phasic, short sarcomere fibres of the fresh water decapod crustacean Cherax destructor (yabby) and in the fast-twitch rat muscle fibres using the mechanically skinned muscle fibre preparation. 2. A robust Ca2+-induced Ca2+-release (CICR) mechanism was present in both long and short sarcomere fibres and 1 mM Mg2+ exerted a strong inhibitory action on the SR Ca2+ release in both fibre types. 3. The SR displayed different properties with respect to Ca2+ loading in the long and the short sarcomere fibres and marked functional differences were identified with respect to Mg2+ inhibition between the two crustacean fibre types. Thus, in long sarcomere fibres, the submaximally loaded SR was able to release Ca2+ when [Mg2+] was lowered from 1 to 0.01 mM in the presence of 8 mM ATPtotal and in the virtual absence of Ca2+ (< 5 nM) even when the CICR was suppressed. In contrast, negligible Ca2+ was released from the submaximally loaded SR of short sarcomere yabby fibres when [Mg2+] was lowered from 1 to 0.01 mM under the same conditions as for the long sarcomere fibres. Nevertheless, the rate of SR Ca2+ release in short sarcomere fibres increased markedly when [Mg2+] was lowered in the presence of [Ca2+] approaching the normal resting levels (50-100 nM). 4. Rat fibres were able to release SR Ca2+ at a faster rate than the long sarcomere yabby fibres when [Mg2+] was lowered from 1 to 0. 01 mM in the virtual absence of Ca2+ but, unlike with yabby fibres, the net rate of Ca2+ release was actually increased for conditions that were considerably less favourable to CICR. 5. In summary, it is concluded that crustacean skeletal muscles have more that one functional type of Ca2+-release channels, that these channels display properties that are intermediate between those of mammalian skeletal and

  6. Effects of age on calcium transport activity of sarcoplasmic reticulum in fast- and slow-twitch rat muscle fibres.

    PubMed Central

    Larsson, L; Salviati, G

    1989-01-01

    1. The calcium transport activity of the sarcoplasmic reticulum (SR) was measured in chemically skinned single fast- and slow-twitch muscle fibres from young (3 months) and old (23-24 months) rats. Contractile properties, the myosin heavy chain (MHC) composition and enzyme histochemical features were studied in relation to the SR characteristics. 2. In fast-twitch single motor units, the contraction time of the isometric twitch increased (P less than 0.001) from 13 +/- 1 ms in young animals to 18 +/- 2 ms in old ones. In the slow-twitch soleus, the contraction (P less than 0.001) and half-relaxation (P less than 0.05) times increased from 30 +/- 5 and 45 +/- 10 ms, respectively, in the young animals to 43 +/- 3 and 55 +/- 4 ms in the old ones. The proportion of slow-twitch (type I) fibres increased (P less than 0.05) with age in the soleus from 92 +/- 6 to 98 +/- 2% and the proportion of fast-twitch fibres (type IIA) decreased (P less than 0.01) from 6 +/- 5 to 0 +/- 0%. 3. The Ca2+ accumulation capacity (an index of SR volume), the rate of Ca2+ uptake and the fractional rate of SR filling (an estimate of the specific activity of the Ca2+ pump) were decreased by 18 (P less than 0.05), 32 (P less than 0.01) and 32% (P less than 0.001), respectively, in the old fast-twitch muscle fibres. In the slow-twitch muscle fibres, on the other hand, no significant age-related changes were observed in the Ca2+ transport activity of the SR. Thus, ageing exerts a differential influence on SR volume and function in fast- and slow-twitch fibres. 4. It is concluded that an age-related impairment of intrinsic SR function and a decrease in SR volume are probable factors underlying the decreased speed of contraction of fast-twitch muscle fibres in old age. In the slow-twitch soleus, on the other hand, one or more other mechanisms are responsible for the age-related decrease in the speed of contraction. The loss of fast-twitch muscle fibres in old soleus is one mechanism, but not the

  7. Mechanical load induces sarcoplasmic wounding and FGF release in differentiated human skeletal muscle cultures

    NASA Technical Reports Server (NTRS)

    Clarke, M. S.; Feeback, D. L.

    1996-01-01

    The transduction mechanism (or mechanisms) responsible for converting a mechanical load into a skeletal muscle growth response are unclear. In this study we have used a mechanically active tissue culture model of differentiated human skeletal muscle cells to investigate the relationship between mechanical load, sarcolemma wounding, fibroblast growth factor release, and skeletal muscle cell growth. Using the Flexcell Strain Unit we demonstrate that as mechanical load increases, so too does the amount of sarcolemma wounding. A similar relationship was also observed between the level of mechanical load inflicted on the cells and the amount of bFGF (FGF2) released into the surrounding medium. In addition, we demonstrate that the muscle cell growth response induced by chronic mechanical loading in culture can be inhibited by the presence of an antibody capable of neutralizing the biological activity of FGF. This study provides direct evidence that mechanically induced, sarcolemma wound-mediated FGF release is an important autocrine mechanism for transducing the stimulus of mechanical load into a skeletal muscle growth response.

  8. Sensory and autonomic neurons project both to the smooth retractor penis and to the striated bulbospongiosus muscles. Neurochemical features of the sympathetic subset.

    PubMed

    Botti, Maddalena; Gazza, Ferdinando; Ragionieri, Luisa; Minelli, Luisa Bo; Panu, Rino

    2012-08-01

    Aim of the present study was to verify, by means of double retrograde neuronal tracers technique, the hypothesis that a subpopulation of sensory and autonomic neurons send collateral axons to both smooth and striated genital muscles. We also wanted to define the neurochemical content of the eventually retrogradelly double labeled (RDL) neurons in the sympathetic trunk ganglia (STG). We used six intact pigs and we injected the tracer Diamidino Yellow (DY) in the smooth left retractor penis muscle (RPM) and the tracer Fast Blue (FB) in the striated left bulbospongiosus muscle (BSM). Rare (2 ± 0.6) RDL neurons were found in the ipsilateral S2 spinal ganglion (SG), 220 ± 42 in the ipsilateral STGs, from L3 to S3, 19 ± 15 in the contralateral S1-S2 ones and 22 ± 5 in the bilateral caudal mesenteric ganglia (CMG). The RDL neurons of the STG were IR for TH (85 ± 13%), DβH (69 ± 17%), NPY (69 ± 23%), nNOS (60 ± 11%), LENK (54 ± 19%), VIP (53±26%), SOM (40 ± 8%), CGRP (34 ± 12%), SP (31 ± 16%), and VAChT (28 ± 3%). Our research highlights the presence of sensory and sympathetic neurons with qualitatively different neurochemical content sending axons both to the smooth RPM and to the striated BSM of the pig. These RDL neurons are likely to project to the smooth vasal musculature to create the ideal physiological conditions in which these muscles can optimize the erectile function. PMID:22707224

  9. Effect of 23-day muscle disuse on sarcoplasmic reticulum Ca2+ properties and contractility in human type I and type II skeletal muscle fibers.

    PubMed

    Lamboley, C R; Wyckelsma, V L; Perry, B D; McKenna, M J; Lamb, G D

    2016-08-01

    Inactivity negatively impacts on skeletal muscle function mainly through muscle atrophy. However, recent evidence suggests that the quality of individual muscle fibers is also altered. This study examined the effects of 23 days of unilateral lower limb suspension (ULLS) on specific force and sarcoplasmic reticulum (SR) Ca(2+) content in individual skinned muscle fibers. Muscle biopsies of the vastus lateralis were taken from six young healthy adults prior to and following ULLS. After disuse, the endogenous SR Ca(2+) content was ∼8% lower in type I fibers and maximal SR Ca(2+) capacity was lower in both type I and type II fibers (-11 and -5%, respectively). The specific force, measured in single skinned fibers from three subjects, decreased significantly after ULLS in type II fibers (-23%) but not in type I fibers (-9%). Western blot analyses showed no significant change in the amounts of myosin heavy chain (MHC) I and MHC IIa following the disuse, whereas the amounts of sarco(endo)plasmic reticulum Ca(2+)-ATPase 1 (SERCA1) and calsequestrin increased by ∼120 and ∼20%, respectively, and the amount of troponin I decreased by ∼21%. These findings suggest that the decline in force and power occurring with muscle disuse is likely to be exacerbated in part by reductions in maximum specific force in type II fibers, and in the amount of releasable SR Ca(2+) in both fiber types, the latter not being attributable to a reduced calsequestrin level. Furthermore, the ∼3-wk disuse in human elicits change in SR properties, in particular a more than twofold upregulation in SERCA1 density, before any fiber-type shift. PMID:27365282

  10. Measurement of Calcium Fluctuations Within the Sarcoplasmic Reticulum of Cultured Smooth Muscle Cells Using FRET-based Confocal Imaging.

    PubMed

    Ziomek, Gabriela; van Breemen, Cornelis; Esfandiarei, Mitra

    2016-01-01

    Maintenance of steady-state calcium (Ca(2+)) levels in the sarcoplasmic reticulum (SR) of vascular smooth muscle cells (VSMCs) is vital to their overall health. A significant portion of intracellular Ca(2+) content is found within the SR stores in VSMCs. As the only intracellular organelle with a close association to the surrounding extracellular space through plasma membrane-SR junctions, the SR can be considered to constitute the first line of response to any irregularity in Ca(2+) transients, or stress experienced by the cell. Among its many functions, one of the most important is its role in the transmission of Ca(2+)-regulated signals throughout the cell to induce further cell-wide reactions downstream. The more common use of cytoplasmic Ca(2+) indicators in this regard is overall insufficient for research into the highly dynamic changes to the intraluminal SR Ca(2+) store that have yet to be fully characterized. Here, we provide a detailed protocol for the direct and clear measurement of luminal SR Ca(2+). This tool is useful for investigation into the nuanced changes in SR Ca(2+) that have significant subsequent effects on the normal function and health of the cell. Fluctuations in SR Ca(2+) content specifically can provide us with a significant amount of information pertaining to cellular responses to disease or stress conditions experienced by the cell. In this method, a modified version of a SR-targeted Ca(2+) indicator, D1SR, is used to detect Ca(2+) fluctuations in response to the introduction of agents to cultured rat aortic smooth muscle cells (SMCs). Following incubation with the D1SR indicator, confocal fluorescence microscopy and fluorescence resonance energy transfer (FRET)-based imaging are used to directly observe changes to intraluminal SR Ca(2+) levels under control conditions and with the addition of agonist agents that function to induce intracellular Ca(2+) movement. PMID:27403723

  11. Activation and propagation of Ca2+ release from inside the sarcoplasmic reticulum network of mammalian skeletal muscle

    PubMed Central

    Cully, Tanya R; Edwards, Joshua N; Launikonis, Bradley S

    2014-01-01

    Skeletal muscle fibres are large and highly elongated cells specialized for producing the force required for posture and movement. The process of controlling the production of force within the muscle, known as excitation–contraction coupling, requires virtually simultaneous release of large amounts of Ca2+ from the sarcoplasmic reticulum (SR) at the level of every sarcomere within the muscle fibre. Here we imaged Ca2+ movements within the SR, tubular (t-) system and in the cytoplasm to observe that the SR of skeletal muscle is a connected network capable of allowing diffusion of Ca2+ within its lumen to promote the propagation of Ca2+ release throughout the fibre under conditions where inhibition of SR ryanodine receptors (RyRs) was reduced. Reduction of cytoplasmic [Mg2+] ([Mg2+]cyto) induced a leak of Ca2+ through RyRs, causing a reduction in SR Ca2+ buffering power argued to be due to a breakdown of SR calsequestrin polymers, leading to a local elevation of [Ca2+]SR. The local rise in [Ca2+]SR, an intra-SR Ca2+ transient, induced a local diffusely rising [Ca2+]cyto. A prolonged Ca2+ wave lasting tens of seconds or more was generated from these events. Ca2+ waves were dependent on the diffusion of Ca2+ within the lumen of the SR and ended as [Ca2+]SR dropped to low levels to inactivate RyRs. Inactivation of RyRs allowed re-accumulation of [Ca2+]SR and the activation of secondary Ca2+ waves in the persistent presence of low [Mg2+]cyto if the threshold [Ca2+]SR for RyR opening could be reached. Secondary Ca2+ waves occurred without an abrupt reduction in SR Ca2+ buffering power. Ca2+ release and wave propagation occurred in the absence of Ca2+-induced Ca2+ release. These observations are consistent with the activation of Ca2+ release through RyRs of lowered cytoplasmic inhibition by [Ca2+]SR or store overload-induced Ca2+ release. Restitution of SR Ca2+ buffering power to its initially high value required imposing normal resting ionic conditions in the cytoplasm

  12. The role of the sarcoplasmic reticulum in neonatal uterine smooth muscle: enhanced role compared to adult rat

    PubMed Central

    Noble, Karen; Wray, Susan

    2002-01-01

    Little is known about contractile activity, response to agonists or excitation-contraction coupling in neonatal smooth muscle. We have therefore investigated 10-day rat uterus to better understand these processes, and compared it to adult uterus to elucidate how control of contractility develops. Spontaneous contractions are present in the 10-day neonatal uterus, although they are not as large or as regular as those present in adult tissues. External Ca2+ entry via L-type Ca2+ channels is the sole source of Ca2+ and is essential for the spontaneous activity. The neonatal uterus was responsive to carbachol or prostaglandin F2α application; it showed a marked stimulation and a clear dissociation between the force and Ca2+ changes. Such sensitization was not apparent in adult rat myometrium. The sarcoplasmic reticulum (SR) had more releasable Ca2+ and contributed more to the response to agonists in neonatal compared to adult tissues. Thus, Ca2+ entry as opposed to SR Ca2+ release contributed much less to the uterine response to agonists in the neonatal, compared to adult tissues. Inhibition of the SR by cyclopiazonic acid also caused a more vigorous increase in Ca2+ and contractile activity, particularly frequency, in the neonatal compared to the adult uterus. Taken together these data suggest that: (1) spontaneous activity is already present by day 10, (2) receptor-coupling and excitation-contraction signalling pathways are functional, (3) the SR and Ca2+ sensitization mechanisms play a more prominent role in the neonate, and (4) there is a shift to a greater reliance on Ca2+ entry and excitability with development of the myometrium. PMID:12456834

  13. [Effect of psychotropic preparations on the activity of transport ATPase of rabbit skeletal muscle sarcoplasmic reticulum].

    PubMed

    Lavretskaia, E F; Tat'ianenko, L V; Lebedeva, O I

    1977-01-01

    The effect exerted by 5 groups of psychotropic agents on b activity of Ca, Mg-dependent ATP-ase of the sarcoplasmatic reticulum in the skeletal muscles of the rabbit and the transport of Ca2+ were looked into. The most profound inhibitory effect was found to be displayed by neuroleptics--phenothiazine derivatives with the piperazine ring in the side chain. Neuroleptics-butyrophenones produced a much less marked inhibitory action. Tricyclic antidepressants noticeably reduced the activity of the enzyme, while MAO inhibitors proved little effective in this respect. Tranquilizers--benzodiazepine derivatives--displayed a moderate inhibitory influence, while trioxazine turned out to be little active. The stimulants caffein, pentylene tetrazol (corazol), as well as high concentrations of lithium salts raised, whereas their low concentrations suppressed the activity of the enzyme. The inhibitory effect of psychotropic agents increased by as much s 11/2--2 times with regard to the enzyme preliminarily activated through incubation with ATP. PMID:140062

  14. Striated perineal muscles: location of autonomic, sensory, and somatic neurons projecting to the male pig bulbospongiosus muscle.

    PubMed

    Botti, Maddalena; Ragionieri, Luisa; Gazza, Ferdinando; Acone, Franca; Bo Minelli, Luisa; Panu, Rino

    2009-11-01

    The location, number, and size of the neurons innervating the bulbospongiosus muscle (BSM) were studied in male pigs, by means of Fast Blue (FB) retrograde transport. After injection of FB into the left BSM, labeled neurons were found bilaterally in the L2-S4 sympathetic trunk ganglia (STGs), in the caudal mesenteric ganglia (CMGs), in the microganglia of the pelvic plexus (PGs), in a dorsolateral area with respect to the central canal of S1-S3 segments of the spinal cord (SC) and in the S1-S4 ipsilateral and S2-S3 contralateral spinal ganglia (SGs). The mean number of labeled FB cells was 3,122 +/- 1,968 in STGs, 979 +/- 667 in CMGs, 108 +/- 104 in PGs, 89 +/- 39 in SC and 77 +/- 23 in SGs. The area of the multipolar neurons was 852 +/- 22 microm(2) in the STGs, 878 +/- 23 microm(2) in the CMGs and 922 +/- 31 microm(2) in the PGs. The multipolar SC neurons had an area of 1,057 +/- 38 microm(2), while pseudounipolar SG cells had dimensions of 2,281 +/- 129 microm(2). Our research enables us to highlight two peculiarities regarding the innervation of the boar BSM: the very high number of labeled autonomic neurons and the particular localization of the motor somatic nucleus. PMID:19718716

  15. Purification of a sarcoplasmic reticulum protein that binds Ca2+ and plasma lipoproteins

    SciTech Connect

    Hofmann, S.L.; Brown, M.S.; Lee, E.; Pathak, R.K.; Anderson, R.G.; Goldstein, J.L. )

    1989-05-15

    A protein in the sarcoplasmic reticulum of rabbit skeletal and cardiac muscle was identified because of its ability to bind 125I-labeled low density lipoprotein (LDL) with high affinity after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This protein, referred to as the 165-kDa protein, is restricted to striated muscle. It was not detected in 14 other tissues, including several that contain smooth muscle, but it appears in rat L6 myoblasts when they differentiate into myocytes. Immunofluorescence and immunoelectron microscopic studies revealed that the protein is present throughout the sarcoplasmic reticulum and the terminal cisternae. It binds 45Ca2+ on nitrocellulose blots and stains metachromatically with Stains-all, a cationic dye that stains Ca2+-binding proteins. It does not appear to be a glycoprotein, and it appears slightly larger than the 160-kDa glycoprotein previously described in sarcoplasmic reticulum. The 165-kDa protein binds LDL, beta-migrating very low density lipoprotein, and a cholesterol-induced high density lipoprotein particle that contains apoprotein E as its sole apoprotein with much higher affinity than it binds high density lipoprotein. The protein is stable to boiling and to treatment with sodium dodecyl sulfate, but it becomes sensitive to these treatments when its cystine residues are reduced and alkylated. The protein was purified 1300-fold to apparent homogeneity from rabbit skeletal muscle membranes. It differs from the cell surface LDL receptor in that (1) its apparent molecular weight is not changed by reduction and alkylation; (2) it is present in Watanabe-heritable hyperlipidemic rabbits, which lack functional LDL receptors; (3) binding of lipoproteins is not inhibited by EDTA; and (4) it is located within the lumen of the sarcoplasmic reticulum where it has no access to plasma lipoproteins.

  16. Isoform composition and gene expression of thick and thin filament proteins in striated muscles of mice after 30-day space flight.

    PubMed

    Ulanova, Anna; Gritsyna, Yulia; Vikhlyantsev, Ivan; Salmov, Nikolay; Bobylev, Alexander; Abdusalamova, Zarema; Rogachevsky, Vadim; Shenkman, Boris; Podlubnaya, Zoya

    2015-01-01

    Changes in isoform composition, gene expression of titin and nebulin, and isoform composition of myosin heavy chains as well as changes in titin phosphorylation level in skeletal (m. gastrocnemius, m. tibialis anterior, and m. psoas) and cardiac muscles of mice were studied after a 30-day-long space flight onboard the Russian spacecraft "BION-M" number 1. A muscle fibre-type shift from slow-to-fast and a decrease in the content of titin and nebulin in the skeletal muscles of animals from "Flight" group was found. Using Pro-Q Diamond staining, an ~3-fold increase in the phosphorylation level of titin in m. gastrocnemius of mice from the "Flight" group was detected. The content of titin and its phosphorylation level in the cardiac muscle of mice from "Flight" and "Control" groups did not differ; nevertheless an increase (2.2 times) in titin gene expression in the myocardium of flight animals was found. The observed changes are discussed in the context of their role in the contractile activity of striated muscles of mice under conditions of weightlessness. PMID:25664316

  17. Isoform Composition and Gene Expression of Thick and Thin Filament Proteins in Striated Muscles of Mice after 30-Day Space Flight

    PubMed Central

    Ulanova, Anna; Gritsyna, Yulia; Vikhlyantsev, Ivan; Salmov, Nikolay; Bobylev, Alexander; Abdusalamova, Zarema; Rogachevsky, Vadim; Shenkman, Boris; Podlubnaya, Zoya

    2015-01-01

    Changes in isoform composition, gene expression of titin and nebulin, and isoform composition of myosin heavy chains as well as changes in titin phosphorylation level in skeletal (m. gastrocnemius, m. tibialis anterior, and m. psoas) and cardiac muscles of mice were studied after a 30-day-long space flight onboard the Russian spacecraft “BION-M” number 1. A muscle fibre-type shift from slow-to-fast and a decrease in the content of titin and nebulin in the skeletal muscles of animals from “Flight” group was found. Using Pro-Q Diamond staining, an ~3-fold increase in the phosphorylation level of titin in m. gastrocnemius of mice from the “Flight” group was detected. The content of titin and its phosphorylation level in the cardiac muscle of mice from “Flight” and “Control” groups did not differ; nevertheless an increase (2.2 times) in titin gene expression in the myocardium of flight animals was found. The observed changes are discussed in the context of their role in the contractile activity of striated muscles of mice under conditions of weightlessness. PMID:25664316

  18. Three-dimensional structure of the M-region (bare zone) of vertebrate striated muscle myosin filaments by single-particle analysis.

    PubMed

    Al-Khayat, Hind A; Kensler, Robert W; Morris, Edward P; Squire, John M

    2010-11-12

    The rods of anti-parallel myosin molecules overlap at the centre of bipolar myosin filaments to produce an M-region (bare zone) that is free of myosin heads. Beyond the M-region edges, myosin molecules aggregate in a parallel fashion to yield the bridge regions of the myosin filaments. Adjacent myosin filaments in striated muscle A-bands are cross-linked by the M-band. Vertebrate striated muscle myosin filaments have a 3-fold rotational symmetry around their long axes. In addition, at the centre of the M-region, there are three 2-fold axes perpendicular to the filament long axis, giving the whole filament dihedral 32-point group symmetry. Here we describe the three-dimensional structure obtained by a single-particle analysis of the M-region of myosin filaments from goldfish skeletal muscle under relaxing conditions and as viewed in negative stain. This is the first single-particle reconstruction of isolated M-regions. The resulting three-dimensional reconstruction reveals details to about 55 Å resolution of the density distribution in the five main nonmyosin densities in the M-band (M6', M4', M1, M4 and M6) and in the myosin head crowns (P1, P2 and P3) at the M-region edges. The outermost crowns in the reconstruction were identified specifically by their close similarity to the corresponding crown levels in our previously published bridge region reconstructions. The packing of myosin molecules into the M-region structure is discussed, and some unidentified densities are highlighted. PMID:20851129

  19. Effects of the phlebotropic drug Daflon 500 mg on postischemic reperfusion injury in striated skin muscle: a histomorphologic study in the hamster.

    PubMed

    Pickelmann, S; Nolte, D; Leiderer, R; Möllmann, M; Schütze, E; Messmer, K

    1999-11-01

    The objective of this study was to investigate the effects of the purified, micronized, flavonoid fraction Daflon 500 mg (S 5682, 90% diosmin and 10% hesperidin) on tissue damage and leukocyte emigration in striated skin muscle after ischemia-reperfusion, as assessed by histomorphometric analysis. The experimental model used was the transparent dorsal skin fold chamber in the awake Syrian golden hamster. Sixty-four animals were randomly allotted to two treatment groups and time points of investigation. Animals were fed with 30 mg kg(-1) body weight Daflon 500 mg (n = 32) or its vehicle, 5% Arabic gum solution (n = 32), as control 8 hours before ischemia. Before induction of a tourniquet ischemia of 4 hours' duration and at 0.5, 2, and 24 hours of reperfusion, tissue sections were preserved for light and electron microscopic analysis (n = seven or eight animals per time point). The number of intravascular and extravascular leukocytes was determined by light microscopic analysis of esterase-positive leukocytes. For quantitative analysis of ischemia-induced endothelial cell damage, the endothelial thickness of capillaries was calculated by a computer-assisted imaging system, whereas the ischemic tissue damage was assessed by means of a score system (grade 0-3) by an independent investigator. The number of emigrated leukocytes was significantly reduced in Daflon 500 mg-treated animals compared with numbers found in control animals. The histomorphologic muscle fiber damage increased after reperfusion in both groups but was significantly reduced in the Daflon 500 mg-treated animals 2 and 24 hours after reperfusion. These results suggest that the emigration of leukocytes plays an important role in the development of postischemic reperfusion injury of striated skin muscle. PMID:10560948

  20. The Influence of Sarcoplasmic Reticulum Ca2+ Concentration on Ca2+ Sparks and Spontaneous Transient Outward Currents in Single Smooth Muscle Cells

    PubMed Central

    ZhuGe, Ronghua; Tuft, Richard A.; Fogarty, Kevin E.; Bellve, Karl; Fay, Fredric S.; Walsh, John V.

    1999-01-01

    Localized, transient elevations in cytosolic Ca2+, known as Ca2+ sparks, caused by Ca2+ release from sarcoplasmic reticulum, are thought to trigger the opening of large conductance Ca2+-activated potassium channels in the plasma membrane resulting in spontaneous transient outward currents (STOCs) in smooth muscle cells. But the precise relationships between Ca2+ concentration within the sarcoplasmic reticulum and a Ca2+ spark and that between a Ca2+ spark and a STOC are not well defined or fully understood. To address these problems, we have employed two approaches using single patch-clamped smooth muscle cells freshly dissociated from toad stomach: a high speed, wide-field imaging system to simultaneously record Ca2+ sparks and STOCs, and a method to simultaneously measure free global Ca2+ concentration in the sarcoplasmic reticulum ([Ca2+]SR) and in the cytosol ([Ca2+]CYTO) along with STOCs. At a holding potential of 0 mV, cells displayed Ca2+ sparks and STOCs. Ca2+ sparks were associated with STOCs; the onset of the sparks coincided with the upstroke of STOCs, and both had approximately the same decay time. The mean increase in [Ca2+]CYTO at the time and location of the spark peak was ∼100 nM above a resting concentration of ∼100 nM. The frequency and amplitude of spontaneous Ca2+ sparks recorded at −80 mV were unchanged for a period of 10 min after removal of extracellular Ca2+ (nominally Ca2+-free solution with 50 μM EGTA), indicating that Ca2+ influx is not necessary for Ca2+sparks. A brief pulse of caffeine (20 mM) elicited a rapid decrease in [Ca2+]SR in association with a surge in [Ca2+]CYTO and a fusion of STOCs, followed by a fast restoration of [Ca2+]CYTO and a gradual recovery of [Ca2+]SR and STOCs. The return of global [Ca2+]CYTO to rest was an order of magnitude faster than the refilling of the sarcoplasmic reticulum with Ca2+. After the global [Ca2+]CYTO was fully restored, recovery of STOC frequency and amplitude were correlated with the

  1. The 90-kDa junctional sarcoplasmic reticulum protein forms an integral part of a supramolecular triad complex in skeletal muscle.

    PubMed

    Froemming, G R; Pette, D; Ohlendieck, K

    1999-08-11

    Although it is well established that voltage-sensing of the alpha(1)-dihydropyridine receptor triggers Ca(2+)-release via the ryanodine receptor during excitation-contraction coupling in skeletal muscle fibers, it remains to be determined which junctional components are responsible for the assembly, maintenance, and stabilization of triads. Here, we analyzed the expression pattern and neighborhood relationship of a novel 90-kDa sarcoplasmic reticulum protein. This protein is highly enriched in the triad fraction and is predominantly expressed in fast-twitching muscle fibers. Chronic low-frequency electro-stimulation induced a drastic decrease in the relative abundance of this protein. Chemical crosslinking showed a potential overlap between the 90-kDa junctional face membrane protein and the ryanodine receptor Ca(2+)-release channel, suggesting tight protein-protein interactions between these two triad components. Hence, Ca(2+)-regulatory muscle proteins have a strong tendency to oligomerize and the triad region of skeletal muscle fibers forms supramolecular membrane complexes involved in the regulation of Ca(2+)-homeostasis and signal transduction. PMID:10441473

  2. A Novel Conserved Isoform of the Ubiquitin Ligase UFD2a/UBE4B Is Expressed Exclusively in Mature Striated Muscle Cells

    PubMed Central

    Mammen, Andrew L.; Mahoney, James A.; St. Germain, Amanda; Badders, Nisha; Taylor, J. Paul; Rosen, Antony; Spinette, Sarah

    2011-01-01

    Yeast Ufd2p was the first identified E4 multiubiquitin chain assembly factor. Its vertebrate homologues later referred to as UFD2a, UBE4B or E4B were also shown to have E3 ubiquitin ligase activity. UFD2a function in the brain has been well established in vivo, and in vitro studies have shown that its activity is essential for proper condensation and segregation of chromosomes during mitosis. Here we show that 2 alternative splice forms of UFD2a, UFD2a-7 and -7/7a, are expressed sequentially during myoblast differentiation of C2C12 cell cultures and during cardiotoxin-induced regeneration of skeletal muscle in mice. UFD2a-7 contains an alternate exon 7, and UFD2a-7/7a, the larger of the 2 isoforms, contains an additional novel exon 7a. Analysis of protein or mRNA expression in mice and zebrafish revealed that a similar pattern of isoform switching occurs during developmental myogenesis of cardiac and skeletal muscle. In vertebrates (humans, rodents, zebrafish), UFD2a-7/7a is expressed only in mature striated muscle. This unique tissue specificity is further validated by the conserved presence of 2 muscle-specific splicing regulatory motifs located in the 3′ introns of exons 7 and 7a. UFD2a interacts with VCP/p97, an AAA-type ATPase implicated in processes whose functions appear to be regulated, in part, through their interaction with one or more of 15 previously identified cofactors. UFD2a-7/7a did not interact with VCP/p97 in yeast 2-hybrid experiments, which may allow the ATPase to bind cofactors that facilitate its muscle-specific functions. We conclude that the regulated expression of these UFD2a isoforms most likely imparts divergent functions that are important for myogenisis. PMID:22174917

  3. Identification of striated muscle activator of Rho signaling (STARS) as a novel calmodulin target by a newly developed genome-wide screen.

    PubMed

    Furuya, Yusui; Denda, Miwako; Sakane, Kyohei; Ogusu, Tomoko; Takahashi, Sumio; Magari, Masaki; Kanayama, Naoki; Morishita, Ryo; Tokumitsu, Hiroshi

    2016-07-01

    To search for novel target(s) of the Ca(2+)-signaling transducer, calmodulin (CaM), we performed a newly developed genome-wide CaM interaction screening of 19,676 GST-fused proteins expressed in human. We identified striated muscle activator of Rho signaling (STARS) as a novel CaM target and characterized its CaM binding ability and found that the Ca(2+)/CaM complex interacted stoichiometrically with the N-terminal region (Ala13-Gln35) of STARS in vitro as well as in living cells. Mutagenesis studies identified Ile20 and Trp33 as the essential hydrophobic residues in CaM anchoring. Furthermore, the CaM binding deficient mutant (Ile20Ala, Trp33Ala) of STARS further enhanced its stimulatory effect on SRF-dependent transcriptional activation. These results suggest a connection between Ca(2+)-signaling via excitation-contraction coupling and the regulation of STARS-mediated gene expression in muscles. PMID:27132186

  4. Emodin-induced muscle contraction of mouse diaphragm and the involvement of Ca2+ influx and Ca2+ release from sarcoplasmic reticulum

    PubMed Central

    Cheng, Y W; Kang, J J

    1998-01-01

    The effects on skeletal muscle of emodin, an anthraquinone, were studied in the mouse isolated diaphragm and sarcoplasmic reticulum (SR) membrane vesicles.Emodin dose-dependently caused muscle contracture, simultaneously depressing twitch amplitude. Neither tubocurarine nor tetrodotoxin blocked the contraction suggesting that it was caused myogenically.The contraction induced by emodin persisted in a Ca2+ free medium with a slight reduction in the maximal force of contraction. The contraction induced by emodin in the Ca2+ free medium was completely blocked when the internal Ca2+ pool of the muscle was depleted by ryanodine. These data suggest that the contraction caused by emodin is due to the release of Ca2+ from the intracellular ryanodine-sensitive pool.In contrast to the effect seen in the Ca2+ free medium, emodin induced a small but consisted contraction in the ryanodine-treated muscle in Krebs medium. The contraction was blocked in the presence of dithiothreitol and was partially blocked by nifedipine, suggesting that oxidation of a sulphhydryl group on the external site of dihydropyridine receptor is involved.Emodin dose-dependently increased Ca2+ release from actively loaded SR vesicles and this effect was blocked by ruthenium red, a specific Ca2+ release channel blocker, and the thiol reducing agent, DTT, suggesting that emodin induced Ca2+ release through oxidation of the critical SH of the ryanodine receptor.[3H]-ryanodine binding was dose-dependently potentiated by emodin in a biphasic manner. The degree of potentiation of ryanodine binding by emodin increased dose-dependently at concentrations up to 10 μM but decreased at higher concentrations of 10–100 μM.These data suggest that muscle contraction induced by emodin is due to Ca2+ release from the SR of skeletal muscle, as a result of oxidation of the ryanodine receptor and influx of extracellular Ca2+ through voltage-dependent Ca2+ channels of the plasma membrane. PMID:9535008

  5. Regulation of sarcoplasmic reticulum Ca2+ ATPase pump expression and its relevance to cardiac muscle physiology and pathology.

    PubMed

    Periasamy, Muthu; Bhupathy, Poornima; Babu, Gopal J

    2008-01-15

    Cardiac sarcoplasmic reticulum (SR) Ca(2+) ATPase (SERCA2a) plays a central role in myocardial contractility. SERCA2a actively transports Ca(2+) into the SR and regulates cytosolic Ca(2+) concentration, SR Ca(2+) load, and the rate of contraction and relaxation of the heart. In the heart, SERCA pump activity is regulated by two small molecular weight proteins: phospholamban (PLB) and sarcolipin (SLN). Decreases in the expression levels of SERCA2a have been observed in a variety of pathological conditions. In addition, altered expression of PLB and SLN has been reported in many cardiac diseases. Thus, SERCA2a is a major regulator of intracellular Ca(2+) homeostasis, and changes in the expression and activity of the SERCA pump contribute to the decreased SR Ca(2+) content and cardiac dysfunction during pathogenesis. In this review, we discuss the mechanisms controlling SERCA pump expression and activity both during normal physiology and under pathological states. PMID:18006443

  6. Voltage-gated Ca(2+) influx through L-type channels contributes to sarcoplasmic reticulum Ca(2+) loading in skeletal muscle.

    PubMed

    Robin, Gaëlle; Allard, Bruno

    2015-11-01

    Muscle contraction is triggered by Ca(2+) ions released from the sarcoplasmic reticulum (SR) in response to depolarization of skeletal muscle fibres. Muscle activation is also associated with a voltage-activated trans-sarcolemmal Ca(2+) influx early identified as a current flowing through L-type Ca(2+) channels. Because removal of external Ca(2+) does not impede fibres from contracting, a negligible role was given to this voltage-activated Ca(2+) entry, although the decline of Ca(2+) release is more pronounced in the absence of Ca(2+) during long-lasting activation. Furthermore, it is not clearly established whether Ca(2+) exclusively flows through L-type channels or in addition through a parallel voltage-activated pathway distinct from L-type channels. Here, by monitoring the quenching of fura-2 fluorescence resulting from Mn(2+) influx in voltage-controlled mouse and zebrafish isolated muscle fibres, we show that the L-type current is the only contributor to Ca(2+) influx during long-lasting depolarizations in skeletal muscle. Calibration of the Mn(2+) quenching signal allowed us to estimate a mean Mn(2+) current of 0.31 ± 0.06 A F(-1) flowing through L-type channels during a train of action potentials. Measurements of SR Ca(2+) changes with fluo-5N in response to depolarization revealed that an elevated voltage-activated Ca(2+) current potentiated SR Ca(2+) loading and addition of external Mn(2+) produced quenching of fluo-5N in the SR, indicating that voltage-activated Ca(2+) /Mn(2+) influx contributes to SR Ca(2+) /Mn(2+) loading. PMID:26383921

  7. Identification of 30 kDa calsequestrin-binding protein, which regulates calcium release from sarcoplasmic reticulum of rabbit skeletal muscle.

    PubMed Central

    Yamaguchi, N; Kasai, M

    1998-01-01

    In a previous study [Yamaguchi, Kawasaki and Kasai (1995) Biochem. Biophys. Res. Commun. 210, 648-653], we showed that the stilbene derivative 4,4'-di-isothiocyanostilbene-2,2'-disulphonic acid activates the Ca2+ channel in the sarcoplasmic reticulum (SR) in rabbit skeletal muscle, and it does not bind to the channel protein itself but to the SR 30 kDa protein. Furthermore, the 30 kDa protein was shown to bind to calsequestrin (CSQ), which is one of the regulators of the Ca2+ release channel in the SR. In the present study, we determined the partial amino acid sequence of the CSQ-binding 30 kDa protein and, consequently, this protein was proved to be highly similar to ADP/ATP translocase (AAT) expressed in the mitochondria in a variety of cells. By Western-blotting analysis, the CSQ-binding 30 kDa protein was recognized by the antibody raised against bovine cardiac AAT and, furthermore, depolarization-induced Ca2+ release monitored in the rabbit skeletal muscle triads was significantly activated by the antibody. As a result of cloning and sequencing of the cDNA encoding AAT of the rabbit skeletal muscle, the amino acid sequence was found to be the same as that of the CSQ-binding 30 kDa protein determined above. Furthermore, the expressed product of the cDNA encoding AAT in Escherichia coli was proved to bind to CSQ. These results suggest that AAT itself is expressed in the rabbit skeletal muscle SR and regulates the Ca2+ release from the SR; that is, excitation-contraction coupling of the skeletal muscle cell. PMID:9794793

  8. Multiple effects of ryanodine on intracellular free Ca2+ in smooth muscle cells from bovine and porcine coronary artery: modulation of sarcoplasmic reticulum function.

    PubMed Central

    Wagner-Mann, C.; Hu, Q.; Sturek, M.

    1992-01-01

    1. The effects of ryanodine and caffeine on intracellular free Ca2+ concentration ([Ca2+]i) were studied by use of fura-2 microfluorometry in single smooth muscle cells freshly dispersed from bovine and porcine coronary artery. 2. Bovine and porcine cells demonstrated similar sensitivities to 10 min of exposure to ryanodine in physiological salt solution (PSS), as determined by comparable dose-dependent decreases in the subsequent [Ca2+]i transient induced by 5 mM caffeine. 3. Ryanodine (10 microM) caused a significant increase in [Ca2+]i to a plateau level 27 +/- 3% and 38 +/- 4% above baseline [Ca2+]i (baseline [Ca2+]i = [Ca2+]i at 0 min) in porcine and bovine cells, respectively, when bathed in PSS. In bovine cells the time required to reach 1/2 the plateau level was only 3 min versus 6 min for porcine cells. 4. The ryanodine-induced plateau increase in [Ca2+]i was 35 +/- 5% above baseline for bovine cells bathed in 0 Ca PSS (PSS including 10 microM EGTA with no added Ca2+), but only 7 +/- 3% above baseline in porcine cells during 10 min exposure to 10 microM ryanodine. In bovine cells [Ca2+]i showed proportional increases when extracellular Ca2+ was increased from the normal 2 mM Ca2+ PSS to 5 and 10 mM. 5. Cells pretreated with caffeine in 0 Ca PSS, which depleted the caffeine-sensitive sarcoplasmic reticulum Ca2+ store, showed no increase in [Ca2+]i when challenged with 10 microM ryanodine. The ryanodine-associated increase in [Ca2+]i, which was sustained in 0 Ca PSS during the 10 min ryanodine exposure in cells not pretreated with caffeine, suggests that ryanodine releases Ca2+ from the sarcoplasmic reticulum, but also inhibits Ca2+ efflux.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 1 PMID:1504718

  9. Response of the JAK-STAT pathway to mammalian hibernation in 13-lined ground squirrel striated muscle.

    PubMed

    Logan, Samantha M; Tessier, Shannon N; Tye, Joann; Storey, Kenneth B

    2016-03-01

    Over the course of the torpor-arousal cycle, hibernators must make behavioral, physiological, and molecular rearrangements in order to keep a very low metabolic rate and retain organ viability. 13-lined ground squirrels (Ictidomys tridecemlineatus) remain immobile during hibernation, and although the mechanisms of skeletal muscle survival are largely unknown, studies have shown minimal muscle loss in hibernating organisms. Additionally, the ground squirrel heart undergoes cold-stress, reversible cardiac hypertrophy, and ischemia-reperfusion without experiencing fatal impairment. This study examines the role of the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway in the regulation of cell stress in cardiac and skeletal muscles, comparing euthermic and hibernating ground squirrels. Immunoblots showed a fivefold decrease in JAK3 expression during torpor in skeletal muscle, along with increases in STAT3 and 5 phosphorylation and suppressors of cytokine signaling-1 (SOCS1) protein levels. Immunoblots also showed coordinated increases in STAT1, 3 and 5 phosphorylation and STAT1 inhibitor protein expression in cardiac muscle during torpor. PCR analysis revealed that the activation of these pro-survival signaling cascades did not result in coordinate changes in downstream genes such as anti-apoptotic B-cell lymphoma-2 (Bcl-2) family gene expression. Overall, these results indicate activation of the JAK-STAT pathway in both cardiac and skeletal muscles, suggesting a response to cellular stress during hibernation. PMID:26885984

  10. Promiscuous Actions of Small Molecule Inhibitors of the Protein Kinase D-Class IIa HDAC Axis in Striated Muscle

    PubMed Central

    Lemon, Douglas D.; Harrison, Brooke C.; Horn, Todd R.; Stratton, Matthew S.; Ferguson, Bradley S.; Wempe, Michael F.; McKinsey, Timothy A.

    2015-01-01

    PKD-mediated phosphorylation of class IIa HDACs frees the MEF2 transcription factor to activate genes that govern muscle differentiation and growth. Studies of the regulation and function of this signaling axis have involved MC1568 and Gö-6976, which are small molecule inhibitors of class IIa HDAC and PKD catalytic activity, respectively. We describe unanticipated effects of these compounds. MC1568 failed to inhibit class IIa HDAC catalytic activity in vitro, and exerted divergent effects on skeletal muscle differentiation compared to a bona fide inhibitor of these HDACs. In cardiomyocytes, Gö-6976 triggered calcium signaling and activated stress-inducible kinases. Based on these findings, caution is warranted when employing MC1568 and Gö-6976 as pharmacological tool compounds to assess functions of class IIa HDACs and PKD. PMID:25816750

  11. The increase in non-cross-bridge forces after stretch of activated striated muscle is related to titin isoforms.

    PubMed

    Cornachione, Anabelle S; Leite, Felipe; Bagni, Maria Angela; Rassier, Dilson E

    2016-01-01

    Skeletal muscles present a non-cross-bridge increase in sarcomere stiffness and tension on Ca(2+) activation, referred to as static stiffness and static tension, respectively. It has been hypothesized that this increase in tension is caused by Ca(2+)-dependent changes in the properties of titin molecules. To verify this hypothesis, we investigated the static tension in muscles containing different titin isoforms. Permeabilized myofibrils were isolated from the psoas, soleus, and heart ventricle from the rabbit, and tested in pCa 9.0 and pCa 4.5, before and after extraction of troponin C, thin filaments, and treatment with the actomyosin inhibitor blebbistatin. The myofibrils were tested with stretches of different amplitudes in sarcomere lengths varying between 1.93 and 3.37 μm for the psoas, 2.68 and 4.21 μm for the soleus, and 1.51 and 2.86 μm for the ventricle. Using gel electrophoresis, we confirmed that the three muscles tested have different titin isoforms. The static tension was present in psoas and soleus myofibrils, but not in ventricle myofibrils, and higher in psoas myofibrils than in soleus myofibrils. These results suggest that the increase in the static tension is directly associated with Ca(2+)-dependent change in titin properties and not associated with changes in titin-actin interactions. PMID:26405100

  12. High-resolution scanning electron-microscopic studies on the three-dimensional structure of mitochondria and sarcoplasmic reticulum in the different twitch muscle fibers of the frog.

    PubMed

    Ogata, T; Yamasaki, Y

    1987-12-01

    The three-dimensional structure of the mitochondria and sarcoplasmic reticulum (SR) in the three types of twitch fibers, i.e., the red, white and intermediate skeletal muscle fibers, of the vastus lateralis muscle of the Japanese meadow frog (Rana nigromaculata nigromaculata Hallowell) was examined by high resolution scanning electron microscopy, after removal of the cytoplasmic matrices. The small red fibers have numerous mitochondrial columns of large diameter, while the large white fibers have a small number of mitochondrial columns of small diameter. In the medium-size intermediate fibers, the number and diameter of the mitochondrial columns are intermediate between those of the red and white fibers. In all three types of fibers, the terminal cisternae and transverse tubules form triads at the level of each Z-line. The thick terminal cisternae continue into much thinner flat intermediate cisternae, through a transitional part where a row of tiny indentations can be observed. Numerous slender longitudinal tubules originating from the intermediate cisternae, extend longitudinally or obliquely and form elongated oval networks of various sizes in front of the A-band, then fuse to form the H-band collar (fenestrated collar) around the myofibrils. On the surface of the H-band collar, small fenestrations as well as tiny hollows are seen. The three-dimensional structure of SR is basically the same in all three muscle fiber-types. However, the SR is sparse on the surface of mitochondria, so the mitochondria-rich red fiber has a smaller total volume of SR than the mitochondria-poor white fiber. The volume of SR of the intermediate fiber is intermediate between other the two. PMID:3690630

  13. Structural and functional correlation of the trypsin-digested Ca2+ release channel of skeletal muscle sarcoplasmic reticulum.

    PubMed

    Meissner, G; Rousseau, E; Lai, F A

    1989-01-25

    The effect of trypsin digestion on the (i) fragmentation pattern, (ii) activity, (iii) [3H]ryanodine binding, and (iv) sedimentation behavior of the skeletal sarcoplasmic reticulum (SR) ryanodine receptor-Ca2+ release channel complex has been examined. Mild tryptic digestion of heavy, junctional-derived SR vesicles resulted in the rapid disappearance of the high molecular weight (Mr approximately 400,000) Ca2+ release channel protein on sodium dodecyl sulfate gels and appearance of bands of lower Mr upon immunoblot analysis, without an appreciable effect on [3H]ryanodine binding or the apparent S value (30 S) of the 3-[3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (Chaps)-solubilized channel complex. Further degradation to bands of Mr greater than 70,000 on immunoblots correlated with a reduction of channel size from 30 S to 10-15 S and loss of high affinity [3H]ryanodine binding to the trypsinized receptor, while low affinity [3H]ryanodine binding and [3H]ryanodine bound prior to digestion were retained. Parallel 45Ca2+ efflux measurements also indicated retention of the Ca2+, Mg2+, and ATP regulatory sites, although Ca2+-induced 45Ca2+ release rates were changed. In planar lipid bilayer-single channel measurements, addition of trypsin to the cytoplasmic side of the high conductance (100 pS in 50 mM Ca2+), Ca2+-activated SR Ca2+ channel initially increased the fraction of channel open time and was followed by a complete and irreversible loss of channel activity. Trypsin did not change the unitary conductance, and was without effect on single channel activity when added to the lumenal side of the channel. PMID:2536370

  14. Multi-Tasking Role of the Mechanosensing Protein Ankrd2 in the Signaling Network of Striated Muscle

    PubMed Central

    Mittempergher, Lorenza; Campanaro, Stefano; Martinelli, Valentina C.; Mouly, Vincent; Valle, Giorgio; Kojic, Snezana; Faulkner, Georgine

    2011-01-01

    Background Ankrd2 (also known as Arpp) together with Ankrd1/CARP and DARP are members of the MARP mechanosensing proteins that form a complex with titin (N2A)/calpain 3 protease/myopalladin. In muscle, Ankrd2 is located in the I-band of the sarcomere and moves to the nucleus of adjacent myofibers on muscle injury. In myoblasts it is predominantly in the nucleus and on differentiation shifts from the nucleus to the cytoplasm. In agreement with its role as a sensor it interacts both with sarcomeric proteins and transcription factors. Methodology/Principal Findings Expression profiling of endogenous Ankrd2 silenced in human myotubes was undertaken to elucidate its role as an intermediary in cell signaling pathways. Silencing Ankrd2 expression altered the expression of genes involved in both intercellular communication (cytokine-cytokine receptor interaction, endocytosis, focal adhesion, tight junction, gap junction and regulation of the actin cytoskeleton) and intracellular communication (calcium, insulin, MAPK, p53, TGF-β and Wnt signaling). The significance of Ankrd2 in cell signaling was strengthened by the fact that we were able to show for the first time that Nkx2.5 and p53 are upstream effectors of the Ankrd2 gene and that Ankrd1/CARP, another MARP member, can modulate the transcriptional ability of MyoD on the Ankrd2 promoter. Another novel finding was the interaction between Ankrd2 and proteins with PDZ and SH3 domains, further supporting its role in signaling. It is noteworthy that we demonstrated that transcription factors PAX6, LHX2, NFIL3 and MECP2, were able to bind both the Ankrd2 protein and its promoter indicating the presence of a regulatory feedback loop mechanism. Conclusions/Significance In conclusion we demonstrate that Ankrd2 is a potent regulator in muscle cells affecting a multitude of pathways and processes. PMID:22016770

  15. Contractile properties and sarcoplasmic reticulum calcium content in type I and type II skeletal muscle fibres in active aged humans

    PubMed Central

    Lamboley, C R; Wyckelsma, V L; Dutka, T L; McKenna, M J; Murphy, R M; Lamb, G D

    2015-01-01

    This study examined the contractile properties and sarcoplasmic reticulum (SR) Ca2+ content in mechanically skinned vastus lateralis muscle fibres of Old (70 ± 4 years) and Young (22 ± 3 years) humans to investigate whether changes in muscle fibre properties contribute to muscle weakness in old age. In type II fibres of Old subjects, specific force was reduced by ∼17% and Ca2+ sensitivity was also reduced (pCa50 decreased ∼0.05 pCa units) relative to that in Young. S-Glutathionylation of fast troponin I (TnIf) markedly increased Ca2+ sensitivity in type II fibres, but the increase was significantly smaller in Old versus Young (+0.136 and +0.164 pCa unit increases, respectively). Endogenous and maximal SR Ca2+ content were significantly smaller in both type I and type II fibres in Old subjects. In fibres of Young, the SR could be nearly fully depleted of Ca2+ by a combined caffeine and low Mg2+ stimulus, whereas in fibres of Old the amount of non-releasable Ca2+ was significantly increased (by > 12% of endogenous Ca2+ content). Western blotting showed an increased proportion of type I fibres in Old subjects, and increased amounts of calsequestrin-2 and calsequestrin-like protein. The findings suggest that muscle weakness in old age is probably attributable in part to (i) an increased proportion of type I fibres, (ii) a reduction in both maximum specific force and Ca2+ sensitivity in type II fibres, and also a decreased ability of S-glutathionylation of TnIf to counter the fatiguing effects of metabolites on Ca2+ sensitivity, and (iii) a reduction in the amount of releasable SR Ca2+ in both fibre types. Key points Muscle weakness in old age is due in large part to an overall loss of skeletal muscle tissue, but it remains uncertain how much also stems from alterations in the properties of the individual muscle fibres. This study examined the contractile properties and amount of stored intracellular calcium in single muscle fibres of Old (70

  16. A phosphorylated conformational state of the (Ca2+-Mg2+)-ATPase of fast skeletal muscle sarcoplasmic reticulum can mediate rapid Ca2+ release.

    PubMed

    Chiesi, M; Wen, Y S

    1983-05-25

    A rapid Ca2+ release from Ca2+-loaded sarcoplasmic reticulum vesicles from fast skeletal muscle can be induced under conditions which permit the formation of a stable phosphorylated intermediate of the (Ca2+-Mg2+)-ATPase. Such a state can be achieved experimentally by phosphorylating the ATPase in the absence of Mg2+ ions, which otherwise would stimulate the dephosphorylation step(s). Also, quercetine stimulates the rapid release of Ca2+ if used in the concentration range which does not produce inhibition of phosphoenzyme formation, but which inhibits phosphoenzyme dephosphorylation. The rapid efflux of Ca2+ ions proceeds as long as the low affinity Ca2+-binding sites facing the lumen of the vesicles are saturated and as long as Ca2+ is removed from the catalytic sites facing the cytosol. A molecular mechanism of the phosphoenzyme-mediated Ca2+ release is proposed. This mechanism is based on a rapid shuttling of the ATPase molecules between an ADP-sensitive and an ADP-insensitive phosphorylated state. PMID:6133856

  17. Force generation and shift of mass between myosin and actin in skinned striated muscle fibres at low calcium concentrations.

    PubMed

    Schiereck, P; van Heijst, B G; Jansen, P M; Schiereck, J; van der Leun, M; Bras, W; de Beer, E L

    1998-01-01

    Skinned muscle fibres from the gracilis muscle of the rabbit were used to record small angle X-ray diffraction spectra under various contractile conditions. The intracellular calcium concentration, expressed as pCa, was varied between 8.0 and 5.74. Equatorial diffraction spectra were fitted by a function consisting of five Gaussian curves and a hyperbola to separate the (1.0), (1.1), (2.0), (2.1) and Z-line diffraction peaks. The hyperbola was used to correct for residual scattering in the preparation. The ratio between the intensities of the (1.1) and (1.0) peaks was defined as the relative transfer of mass between myosin and actin, due to crossbridge formation after activation by calcium. The relation between the ratio and the relative force of the fibre (normalized to the force at pCa 5.74 and sarcomere length 2.0 microns) was linear. At high pCa (from pCa 6.34 to 8.0) no active force was observed, while the ratio still decreased. Sarcomere length was recorded by laser diffraction. The laser diffraction patterns did not show changes in sarcomere length due to activation in the high pCa range (between 8.0 and 6.34). From these results the conclusion is drawn that crossbridge movement occurs even at subthreshold calcium concentrations in the cell, when no active force is exerted. Since no force is generated this movement may be related to crossbridges in the weakly bound state. PMID:9791940

  18. Acute effects of taurine on sarcoplasmic reticulum Ca2+ accumulation and contractility in human type I and type II skeletal muscle fibers.

    PubMed

    Dutka, T L; Lamboley, C R; Murphy, R M; Lamb, G D

    2014-10-01

    Taurine occurs in high concentrations in muscle and is implicated in numerous physiological processes, yet its effects on many aspects of contractility remain unclear. Using mechanically skinned segments of human vastus lateralis muscle fibers, we characterized the effects of taurine on sarcoplasmic reticulum (SR) Ca2+ accumulation and contractile apparatus properties in type I and type II fibers. Prolonged myoplasmic exposure (>10 min) to taurine substantially increased the rate of accumulation of Ca2+ by the SR in both fiber types, with no change in the maximum amount accumulated; no such effect was found with carnosine. SR Ca2+ accumulation was similar with 10 or 20 mM taurine, but was significantly slower at 5 mM taurine. Cytoplasmic taurine (20 mM) had no detectable effects on the responsiveness of the Ca2+ release channels in either fiber type. Taurine caused a small increase in Ca2+ sensitivity of the contractile apparatus in type I fibers, but type II fibers were unaffected; maximum Ca(2+)-activated force was unchanged in both cases. The effects of taurine on SR Ca2+ accumulation (1) only became apparent after prolonged cytoplasmic exposure, and (2) persisted for some minutes after complete removal of taurine from the cytoplasm, consistent with the hypothesis that the effects were due to an action of taurine from inside the SR. In summary, taurine potentiates the rate of SR Ca2+ uptake in both type I and type II human fibers, possibly via an action from within the SR lumen, with the degree of potentiation being significantly reduced at low physiological taurine levels. PMID:25123198

  19. Some relations between changes in the linear electrical properties of striated muscle fibers and changes in ultrastructure.

    PubMed

    Freygang, W H; Rapoport, S I; Peachey, L D

    1967-11-01

    Some of the linear electrical properties of frog sartorius muscle have been investigated in Ringer's fluid and in a Ringer fluid made hypertonic by the addition of sucrose or NaCl. Electrical constants were determined from measurements of the phase angle of the admittance of a fiber for an applied alternating current, from measurements of the voltage induced by an inward pulse of current, and from measurements of the conduction velocity of the action potential and the time constant of its foot. The dilation of the transverse tubular system induced by the sucrose hypertonic Ringer fluid was correlated with the change in the electrical constants. From this it is concluded that a two time constant equivalent circuit for the membrane, as proposed by Falk and Fatt, is in good agreement with our results. Both the area of the membrane of the transverse tubular system, and the capacity (c(e)) attributed to it, increased in the sucrose hypertonic Ringer fluid. The resistance r(e), which is in series with c(e), did not fall when the transverse tubular system was dilated and probably is not located in that system. PMID:6063689

  20. K201 (JTV519) is a Ca2+-Dependent Blocker of SERCA and a Partial Agonist of Ryanodine Receptors in Striated Muscle.

    PubMed

    Darcy, Yuanzhao L; Diaz-Sylvester, Paula L; Copello, Julio A

    2016-08-01

    K201 (JTV-519) may prevent abnormal Ca(2+) leak from the sarcoplasmic reticulum (SR) in the ischemic heart and skeletal muscle (SkM) by stabilizing the ryanodine receptors (RyRs; RyR1 and RyR2, respectively). We tested direct modulation of the SR Ca(2+)-stimulated ATPase (SERCA) and RyRs by K201. In isolated cardiac and SkM SR microsomes, K201 slowed the rate of SR Ca(2+) loading, suggesting potential SERCA block and/or RyR agonism. K201 displayed Ca(2+)-dependent inhibition of SERCA-dependent ATPase activity, which was measured in microsomes incubated with 200, 2, and 0.25 µM Ca(2+) and with the half-maximal K201 inhibitory doses (IC50) estimated at 130, 19, and 9 µM (cardiac muscle) and 104, 13, and 5 µM (SkM SR). K201 (≥5 µM) increased RyR1-mediated Ca(2+) release from SkM microsomes. Maximal K201 doses at 80 µM produced ∼37% of the increase in SkM SR Ca(2+) release observed with the RyR agonist caffeine. K201 (≥5 µM) increased the open probability (Po) of very active ("high-activity") RyR1 of SkM reconstituted into bilayers, but it had no effect on "low-activity" channels. Likewise, K201 activated cardiac RyR2 under systolic Ca(2+) conditions (∼5 µM; channels at Po ∼0.3) but not under diastolic Ca(2+) conditions (∼100 nM; Po < 0.01). Thus, K201-induced the inhibition of SR Ca(2+) leak found in cell-system studies may relate to potentially potent SERCA block under resting Ca(2+) conditions. SERCA block likely produces mild SR depletion in normal conditions but could prevent SR Ca(2+) overload under pathologic conditions, thus precluding abnormal RyR-mediated Ca(2+) release. PMID:27235390

  1. Skeletal muscle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There are approximately 650-850 muscles in the human body these include skeletal (striated), smooth and cardiac muscle. The approximation is based on what some anatomists consider separate muscle or muscle systems. Muscles are classified based on their anatomy (striated vs. smooth) and if they are v...

  2. Sarcoplasmic reticulum Ca2+ uptake and leak properties, and SERCA isoform expression, in type I and type II fibres of human skeletal muscle

    PubMed Central

    Lamboley, C R; Murphy, R M; McKenna, M J; Lamb, G D

    2014-01-01

    The Ca2+ uptake properties of the sarcoplasmic reticulum (SR) were compared between type I and type II fibres of vastus lateralis muscle of young healthy adults. Individual mechanically skinned muscle fibres were exposed to solutions with the free [Ca2+] heavily buffered in the pCa range (–log10[Ca2+]) 7.3–6.0 for set times and the amount of net SR Ca2+ accumulation determined from the force response elicited upon emptying the SR of all Ca2+. Western blotting was used to determine fibre type and the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) isoform present in every fibre examined. Type I fibres contained only SERCA2 and displayed half-maximal Ca2+ uptake rate at ∼pCa 6.8, whereas type II fibres contained only SERCA1 and displayed half-maximal Ca2+ uptake rate at ∼pCa 6.6. Maximal Ca2+ uptake rate was ∼0.18 and ∼0.21 mmol Ca2+ (l fibre)–1 s–1 in type I and type II fibres, respectively, in good accord with previously measured SR ATPase activity. Increasing free [Mg2+] from 1 to 3 mm had no significant effect on the net Ca2+ uptake rate at pCa 6.0, indicating that there was little or no calcium-induced calcium release occurring through the Ca2+ release channels during uptake in either fibre type. Ca2+ leakage from the SR at pCa 8.5, which is thought to occur at least in part through the SERCA, was ∼2-fold lower in type II fibres than in type I fibres, and was little affected by the presence of ADP, in marked contrast to the larger SR Ca2+ leak observed in rat muscle fibres under the same conditions. The higher affinity of Ca2+ uptake in the type I human fibres can account for the higher relative level of SR Ca2+ loading observed in type I compared to type II fibres, and the SR Ca2+ leakage characteristics of the human fibres suggest that the SERCAs are regulated differently from those in rat and contribute comparatively less to resting metabolic rate. PMID:24469076

  3. Ultrastructural study of muscles fibers in tick Hyalomma (Hyalomma) anatolicum anatolicum (Ixodoidea: Ixodidae).

    PubMed

    Bughdadi, Faisal A

    2010-09-01

    In the present study, ticks were obtained from a colony maintained at 28 degrees C and 75% relative humidity in at the Department of Biology, University College Umm Al-Qura University, Saudi Arabia and the Transmission Electron Microscope technique (TEM) was used to describes the ultrastructure and description of muscle of the of ixodid tick Hyalomma (Hyalomma) anatolicum anatolicum. The results showed that muscles of the unfed ticks Hyalomma (Hyalomma) anatolicum anatolicum in longitudinal sections are spindle-shaped to cylindrical muscle fibers. In the unfed nymph Hyalomma (Hyalomma) anatolicum anatolicum skeletal and visceral muscles are distinguished according to structure, function and position. These muscles include the capitulum, dorsoventral and leg oblique muscles. All muscle fibers are ensheathed (covered by sheath) in a sarcolemma. Their muscle fibers have striated pattern of successive sarcomeres whose thick myosin filaments are surrounded by orbitals of up to 12 thin actin filaments. The cytoplasm of the epidermal cell appears largely devoted with complicated microtubules present in parallel with long axis of adjacent muscle fibers. The cell membrane invaginates into tubular system extending deeply into the sarcoplasm and closely associated to cisternae of sarcoplasmic reticulum. The tubular system and sarcoplasmic reticulum forming two-membered (dyads) are considered to be the main route of calcium ions whose movement are synchronized with the motor impulse to control muscles contraction. In the sarcoplasm two types of muscle fibers are recognized according to thickness and density and mitochondrial size, distribution and population. Both skeletal and visceral muscles are invaginated by tracheoles and innervated by nerve axons containing synaptic vesicles. The actin and myosin filaments are slightly interrupted and the tubular system sarcoplasmic reticulum is well demonstrated. PMID:21313907

  4. Superoxide radicals stimulate IP sub 3 -induced Ca sup 2+ -release from vascular smooth muscle sarcoplasmic reticulum

    SciTech Connect

    Ford, G.D.; Suzuki, Y. )

    1991-03-15

    Oxygen free radicals have been implicated in a variety of pathophysiological conditions and vascular smooth muscle can be a site of damage in such oxygen toxicity. Mechanisms of the effects of these radials on the vascular smooth muscle at the cellular level, however, have not been well studied. In the present study, the authors report that the inositol 1,4,5-trisphosphate (IP{sub 3})-induced Ca{sup 2+}-release from bovine aortic SR was also affected by O{sub 2}{sup {minus}}. Hypoxanthine plus xanthine oxidase in the presence of catalase stimulated the IP{sub 3}-induced Ca{sup 2+}-release from SR monitored using arsenazo III. At 10 {mu}M IP{sub 3}, the release was doubled by O{sub 2}{sup {minus}} treatment. As a consequence of using higher SR protein concentrations required to observe the Ca{sup 2+}-uptake inhibition induced by O{sub 2}{sup {minus}}. Since the effect of O{sub 2}{sup {minus}} was not seen when a non-hydrolyzable analogue of IP{sub 3} is used to induce Ca{sup 2+}-release, O{sub 2}{sup {minus}} may be inhibiting the degradation processes of IP{sub 3} rather than having an influence on the release channel per se.

  5. Calcium buffering properties of sarcoplasmic reticulum and calcium-induced Ca2+ release during the quasi-steady level of release in twitch fibers from frog skeletal muscle

    PubMed Central

    Fénelon, Karine; Lamboley, Cédric R.H.; Carrier, Nicole

    2012-01-01

    Experiments were performed to characterize the properties of the intrinsic Ca2+ buffers in the sarcoplasmic reticulum (SR) of cut fibers from frog twitch muscle. The concentrations of total and free calcium ions within the SR ([CaT]SR and [Ca2+]SR) were measured, respectively, with the EGTA/phenol red method and tetramethylmurexide (a low affinity Ca2+ indicator). Results indicate SR Ca2+ buffering was consistent with a single cooperative-binding component or a combination of a cooperative-binding component and a linear binding component accounting for 20% or less of the bound Ca2+. Under the assumption of a single cooperative-binding component, the most likely resting values of [Ca2+]SR and [CaT]SR are 0.67 and 17.1 mM, respectively, and the dissociation constant, Hill coefficient, and concentration of the Ca-binding sites are 0.78 mM, 3.0, and 44 mM, respectively. This information can be used to calculate a variable proportional to the Ca2+ permeability of the SR, namely d[CaT]SR/dt ÷ [Ca2+]SR (denoted release permeability), in experiments in which only [CaT]SR or [Ca2+]SR is measured. In response to a voltage-clamp step to −20 mV at 15°C, the release permeability reaches an early peak followed by a rapid decline to a quasi-steady level that lasts ∼50 ms, followed by a slower decline during which the release permeability decreases by at least threefold. During the quasi-steady level of release, the release amplitude is 3.3-fold greater than expected from voltage activation alone, a result consistent with the recruitment by Ca-induced Ca2+ release of 2.3 SR Ca2+ release channels neighboring each channel activated by its associated voltage sensor. Release permeability at −60 mV increases as [CaT]SR decreases from its resting physiological level to ∼0.1 of this level. This result argues against a release termination mechanism proposed in mammalian muscle fibers in which a luminal sensor of [Ca2+]SR inhibits release when [CaT]SR declines to a low level

  6. Differential effects of sarcoplasmic reticular Ca(2+)-ATPase inhibition on charge movements and calcium transients in intact amphibian skeletal muscle fibres.

    PubMed

    Chawla, Sangeeta; Skepper, Jeremy N; Huang, Christopher L-H

    2002-03-15

    A hypothesis in which intramembrane charge reflects a voltage sensing process allosterically coupled to transitions in ryanodine receptor (RyR)-Ca(2+) release channels as opposed to one driven by release of intracellularly stored Ca(2+) would predict that such charging phenomena should persist in skeletal muscle fibres unable to release stored Ca(2+). Charge movement components were accordingly investigated in intact voltage-clamped amphibian fibres treated with known sarcoplasmic reticular (SR) Ca(2+)-ATPase inhibitors. Cyclopiazonic acid (CPA) pretreatment abolished Ca(2+) transients in fluo-3-loaded fibres following even prolonged applications of caffeine (10 mM) or K(+) (122 mM). Both CPA and thapsigargin (TG) transformed charge movements that included delayed (q(gamma)) "hump" components into simpler decays. However, steady-state charge-voltage characteristics were conserved to values (maximum charge, Q(max) approximately equal to 20-25 nC microF(-1); transition voltage, V* approximately equal to -40 to-50 mV; steepness factor, k approximately equal to 6-9 mV; holding voltage -90 mV) indicating persistent q(gamma) charge. The features of charge inactivation similarly suggested persistent q(beta) and q(gamma) charge contributions in CPA-treated fibres. Perchlorate (8.0 mM) restored the delayed kinetics shown by "on" q(gamma) charge movements, prolonged their "off" decays, conserved both Q(max) and k, yet failed to restore the capacity of such CPA-treated fibres for Ca(2+) release. Introduction of perchlorate (8.0 mM) or caffeine (0.2 mM) to tetracaine (2.0 mM)-treated fibres, also known to restore q(gamma) charge, similarly failed to restore Ca(2+) transients. Steady-state intramembrane q(gamma) charge thus persists with modified kinetics that can be restored to its normally complex waveform by perchlorate, even in intact muscle fibres unable to release Ca(2+). It is thus unlikely that q(gamma) charge movement is a consequence of SR Ca(2+) release rather than

  7. Filament lattice of frog striated muscle. Radial forces, lattice stability, and filament compression in the A-band of relaxed and rigor muscle.

    PubMed Central

    Millman, B M; Irving, T C

    1988-01-01

    Repulsive pressure in the A-band filament lattice of relaxed frog skeletal muscle has been measured as a function of interfilament spacing using an osmotic shrinking technique. Much improved chemical skinning was obtained when the muscles were equilibrated in the presence of EGTA before skinning. The lattice shrank with increasing external osmotic pressure. At any specific pressure, the lattice spacing in relaxed muscle was smaller than that of muscle in rigor, except at low pressures where the reverse was found. The lattice spacing was the same in the two states at a spacing close to that found in vivo. The data were consistent with an electrostatic repulsion over most of the pressure range. For relaxed muscle, the data lay close to electrostatic pressure curves for a thick filament charge diameter of approximately 26 nm, suggesting that charges stabilizing the lattice are situated about midway along the thick filament projections (HMM-S1). At low pressures, observed spacings were larger than calculated, consistent with the idea that thick filament projections move away from the filament backbone. Under all conditions studied, relaxed and rigor, at short and very long sarcomere lengths, the filament lattice could be modeled by assuming a repulsive electrostatic pressure, a weak attractive pressure, and a radial stiffness of the thick filaments (projections) that differed between relaxed and rigor conditions. Each thick filament projection could be compressed by approximately 5 or 2.6 nm requiring a force of 1.3 or 80 pN for relaxed and rigor conditions respectively. PMID:3264728

  8. Effects of free oxygen radicals on Ca2+ release mechanisms in the sarcoplasmic reticulum of scallop (Pecten jacobaeus) adductor muscle.

    PubMed

    Burlando, B; Viarengo, A; Pertica, M; Ponzano, E; Orunesu, M

    1997-08-01

    In vitro oxyradical effects on SR Ca2+ regulation were studied by using a SR-containing cell-free preparation from scallop (Pecten jacobaeus) adductor muscle. Ca2+ variations were fluorimetrically detected after incubation with Fluo-3 in the presence of ATP. Exposure to Fe3+/ascorbate produced dose-dependent Ca2+ release from SR vesicles, eventually leading to massive Ca2+ loss. Exposure to hypoxanthine/xanthine oxidase also caused Ca2+ release but at a much slower rate. Pre-incubations with catalase or with the hydroxyl radical scavenger KMBA led to a significant decrease in the Fe3+/ascorbate-induced Ca2+ release rate and to a delay of massive Ca2+ loss. Pre-incubations with GSH or DTT strongly reduced the Ca2+ release caused by Fe3+/ascorbate and, moreover, they prevented massive Ca2+ loss from SR vesicles. Addition of GSH or DTT after Fe3+/ascorbate promptly reduced the Ca2+ release rate and delayed massive Ca2+ release. Pre-incubation with the SR Ca2+ channel blocker ruthenium red strongly reduced the Ca2+ release caused by Fe3+/ascorbate, and also prevented massive Ca2+ loss. In the presence of ruthenium red, Fe3+/ascorbate treatments followed by Ca2+ addition revealed that Ca2+ uptake inhibition was slower than Ca2+ release. Taken together, data showed that free radicals and, in particular, hydroxyl radicals, affected the scallop SR Ca2+ regulation. This mainly occurred through Ca2+ channel opening, most likely triggered by sulfhydryl oxidation, which eventually led to massive Ca2+ release from SR vesicles. The demonstration of a specific effect of oxyradicals on SR Ca2+ channels is in line with their possible involvement in cell signaling. PMID:9292226

  9. Effects of diet on the function of sarcoplasmic reticulum.

    PubMed Central

    Gould, G W; McWhirter, J M; East, J M; Lee, A G

    1987-01-01

    We have examined the effect of diet on the phospholipid composition of the sarcoplasmic reticulum of rabbit muscle. Enriching the diet with corn or fish oil results in significant changes in the fatty acyl chain composition of the various phospholipid classes, with relatively little change in the relative contents of the phospholipids. These alterations in composition have no significant effect on the ATPase activity of vesicles of sarcoplasmic reticulum or on the pattern of Ca2+ uptake and release. PMID:2959280

  10. Striated morphology during electrodeposition

    SciTech Connect

    Jorne, J.; Lee, M.G.

    1996-03-01

    Comparative study of striated morphologies obtained during the electrodeposition of various metals is performed using rotating electrodes. The formation of striation during electrodeposition of zinc, copper, and silver follows the streamlines of the fluid, and is observed to be accompanied by small or negative polarization resistance. The spacings between striae depends strongly on the applied current density. The spacing decreases with current density in the case of zinc and silver, however, a reverse trend is observed in the case of copper. Linear stability analysis shows that spatial multiplicity occurs when ({partial_derivative}i/{partial_derivative}C){sub {eta}} < 0. The experimentally observed spacings between striae (0.1 {approximately} 1 mm) are in agreement with the wavelength obtained from the linear stability analysis. The analysis of polarization and striation data shows fairly good qualitative agreement with respect to the effects of current density, diffusion layer thickness, and electrolyte concentration on striation.

  11. Spectroscopic and ITC study of the conformational change upon Ca{sup 2+}-binding in TnC C-lobe and TnI peptide complex from Akazara scallop striated muscle

    SciTech Connect

    Yumoto, Fumiaki; Tanaka, Hiroyuki; Nagata, Koji; Miyauchi, Yumiko; Miyakawa, Takuya; Ojima, Takao; Tanokura, Masaru

    2008-04-25

    Akazara scallop (Chlamys nipponensis akazara) troponin C (TnC) of striated adductor muscle binds only one Ca{sup 2+} ion at the C-terminal EF-hand motif (Site IV), but it works as the Ca{sup 2+}-dependent regulator in adductor muscle contraction. In addition, the scallop troponin (Tn) has been thought to regulate muscle contraction via activating mechanisms that involve the region spanning from the TnC C-lobe (C-lobe) binding site to the inhibitory region of the TnI, and no alternative binding of the TnI C-terminal region to TnC because of no similarity between second TnC-binding regions of vertebrate and the scallop TnIs. To clarify the Ca{sup 2+}-regulatory mechanism of muscle contraction by scallop Tn, we have analyzed the Ca{sup 2+}-binding properties of the complex of TnC C-lobe and TnI peptide, and their interaction using isothermal titration microcalorimetry, nuclear magnetic resonance, circular dichroism, and gel filtration chromatography. The results showed that single Ca{sup 2+}-binding to the Site IV leads to a structural transition not only in Site IV but also Site III through the structural network in the C-lobe of scallop TnC. We therefore assumed that the effect of Ca{sup 2+}-binding must lead to a change in the interaction mode between the C-lobe of TnC and the TnI peptide. The change should be the first event of the transmission of Ca{sup 2+} signal to TnI in Tn ternary complex.

  12. Hyperactivation of L-type voltage-gated Ca2+ channels in Caenorhabditis elegans striated muscle can result from point mutations in the IS6 or the IIIS4 segment of the α1 subunit.

    PubMed

    Lainé, Viviane; Ségor, Jean Rony; Zhan, Hong; Bessereau, Jean-Louis; Jospin, Maelle

    2014-11-01

    Several human diseases, including hypokalemic periodic paralysis and Timothy syndrome, are caused by mutations in voltage-gated calcium channels. The effects of these mutations are not always well understood, partially because of difficulties in expressing these channels in heterologous systems. The use of Caenorhabditis elegans could be an alternative approach to determine the effects of mutations on voltage-gated calcium channel function because all the main types of voltage-gated calcium channels are found in C. elegans, a large panel of mutations already exists and efficient genetic tools are available to engineer customized mutations in any gene. In this study, we characterize the effects of two gain-of-function mutations in egl-19, which encodes the L-type calcium channel α1 subunit. One of these mutations, ad695, leads to the replacement of a hydrophobic residue in the IIIS4 segment. The other mutation, n2368, changes a conserved glycine of IS6 segment; this mutation has been identified in patients with Timothy syndrome. We show that both egl-19 (gain-of-function) mutants have defects in locomotion and morphology that are linked to higher muscle tone. Using in situ electrophysiological approaches in striated muscle cells, we provide evidence that this high muscle tone is due to a shift of the voltage dependency towards negative potentials, associated with a decrease of the inactivation rate of the L-type Ca(2+) current. Moreover, we show that the maximal conductance of the Ca(2+) current is decreased in the strongest mutant egl-19(n2368), and that this decrease is correlated with a mislocalization of the channel. PMID:25214488

  13. Rapid Lateral Diffusion of Phospholipids in Rabbit Sarcoplasmic Reticulum

    PubMed Central

    Scandella, Carl J.; Devaux, Philippe; McConnell, Harden M.

    1972-01-01

    Phospholipid spin labels incorporated in the sarcoplasmic reticulum from rabbit-skeletal muscle undergo rapid lateral diffusion within the plane of the membrane. The diffusion constant, D, is 6×10-8 cm2/sec at 37°. With this diffusion constant, a phospholipid molecule can diffuse a distance of the order of 5000 nm in 1 sec. PMID:4506073

  14. Characterization of a myotoxin from the Duvernoy's gland secretion of the xenodontine colubrid Philodryas olfersii (green snake): effects on striated muscle and the neuromuscular junction.

    PubMed

    Prado-Franceschi, J; Hyslop, S; Cogo, J C; Andrade, A L; Assakura, M T; Reichl, A P; Cruz-Höfling, M A; Rodrigues-Simioni, L

    1998-10-01

    A myotoxin has been isolated from the Duvernoy's gland (DG) secretion of the xenodontine colubrid Philodrvas olfersii (green snake) by gel filtration on Sephadex G-100 SF. Under non-reducing and reducing conditions in SDS-PAGE, the myotoxin migrates as a single band with a mol. wt. of 20000. The toxin has 182 amino acid residues (approximately 20% acidic), a pI of 4.8 and a blocked N-terminal. In the chick biventer cervicis preparation, P. olfersii myotoxin partially blocks potassium-evoked contractures without affecting either the twitch-tension resulting from indirect stimulation or the contractures evoked by acetylcholine. Both the DG secretion and the myotoxin increase the serum creatine kinase (CK) levels of mice and stimulate the release of CK from the biventer cervicis preparation in a dose- and time-dependent manner. The varying degrees of muscle cell lysis and extensive widening of the intercellular spaces caused by the DG secretion are reproduced by the myotoxin, with the exception that in the latter the partial or total loss of transverse muscle striations is restricted to the muscle periphery. This myotoxin is the first such protein to be characterized from a DG secretion. PMID:9723839

  15. The effects of Duvernoy's gland secretion from the xenodontine colubrid Philodryas olfersii on striated muscle and the neuromuscular junction: partial characterization of a neuromuscular fraction.

    PubMed

    Prado-Franceschi, J; Hyslop, S; Cogo, J C; Andrade, A L; Assakura, M; Cruz-Höfling, M A; Rodrigues-Simioni, L

    1996-04-01

    The effect of Philodryas olfersii Duvernoy's secretion was studied in vivo in mice and chicks as well as in the mouse phrenic nerve-diaphragm and the chick biventer cervicis preparations. The whole secretion (20-40 micrograms/ml) increased the creatine kinase (CK) levels in mice but had no effect on the mouse phrenic nerve-diaphragm preparation. In the chick, the secretion caused head drop and paresia as well as irreversible blockade of the twitch-tension evoked by indirect stimulation in the chick biventer cervicis preparation (50% paralysis in 34.5 +/- 2.7 min, n = 4). The secretion also caused muscle contracture (30% of the maximal twitch-tension generated) after a latency of nearly 9 min. Following fractionation on a Superose 12 FPLC column, the neuromuscular activity was recovered in the high mol. wt fraction (Peak I). At a concentration of 10 micrograms/ml in the chick biventer cervicis preparation, Peak I caused 50% paralysis within 18.5 +/- 3.0 min (n = 4), and evoked a strong contracture (70% of the maximal twitch-tension generated). The contractile responses of the chick preparation to ACh and KCL were partially blocked (90%) by the whole secretion and totally blocked by Peak I. CK release was increased by the whole secretion but not by Peak I. The whole secretion also produced various degrees of muscle cell lysis and extensive widening of the intercellular spaces. The latter showed a loosely arranged membranous network. In general, Peak I caused only minor morphological alterations compared with the whole secretion, although these were still significantly different from those observed in the control preparations. The changes principally involved hypercontraction of the muscle fibers. Based on the above results, we conclude that Peak I contains the factor(s) responsible for the in vitro effects on neuromuscular transmission, whereas the direct myotoxic effect is apparently caused by at least one other component of the Duvernoy's secretion. PMID:8735245

  16. Effects of carnosine on contractile apparatus Ca²⁺ sensitivity and sarcoplasmic reticulum Ca²⁺ release in human skeletal muscle fibers.

    PubMed

    Dutka, T L; Lamboley, C R; McKenna, M J; Murphy, R M; Lamb, G D

    2012-03-01

    There is considerable interest in potential ergogenic and therapeutic effects of increasing skeletal muscle carnosine content, although its effects on excitation-contraction (EC) coupling in human muscle have not been defined. Consequently, we sought to characterize what effects carnosine, at levels attained by supplementation, has on human muscle fiber function, using a preparation with all key EC coupling proteins in their in situ positions. Fiber segments, obtained from vastus lateralis muscle of human subjects by needle biopsy, were mechanically skinned, and their Ca(2+) release and contractile apparatus properties were characterized. Ca(2+) sensitivity of the contractile apparatus was significantly increased by 8 and 16 mM carnosine (increase in pCa(50) of 0.073 ± 0.007 and 0.116 ± 0.006 pCa units, respectively, in six type I fibers, and 0.063 ± 0.018 and 0.103 ± 0.013 pCa units, respectively, in five type II fibers). Caffeine-induced force responses were potentiated by 8 mM carnosine in both type I and II fibers, with the potentiation in type II fibers being entirely explicable by the increase in Ca(2+) sensitivity of the contractile apparatus caused by carnosine. However, the potentiation of caffeine-induced responses caused by carnosine in type I fibers was beyond that expected from the associated increase in Ca(2+) sensitivity of the contractile apparatus and suggestive of increased Ca(2+)-induced Ca(2+) release. Thus increasing muscle carnosine content likely confers benefits to muscle performance in both fiber types by increasing the Ca(2+) sensitivity of the contractile apparatus and possibly also by aiding Ca(2+) release in type I fibers, helping to lessen or slow the decline in muscle performance during fatiguing stimulation. PMID:22174397

  17. Types of muscle tissue (image)

    MedlinePlus

    The 3 types of muscle tissue are cardiac, smooth, and skeletal. Cardiac muscle cells are located in the walls of the heart, appear striated, and are under involuntary control. Smooth muscle fibers are located in walls of hollow ...

  18. Types of muscle tissue (image)

    MedlinePlus

    ... appear striated, and are under involuntary control. Smooth muscle fibers are located in walls of hollow visceral organs, ... shaped, and are also under involuntary control. Skeletal muscle fibers occur in muscles which are attached to the ...

  19. Dietary ractopamine influences sarcoplasmic proteome profile of pork Longissimus thoracis.

    PubMed

    Costa-Lima, Bruno R C; Suman, Surendranath P; Li, Shuting; Beach, Carol M; Silva, Teofilo J P; Silveira, Expedito T F; Bohrer, Benjamin M; Boler, Dustin D

    2015-05-01

    Dietary ractopamine improves pork leanness, whereas its effect on sarcoplasmic proteome has not been characterized. Therefore, the influence of ractopamine on sarcoplasmic proteome of post-mortem pork Longissimus thoracis muscle was examined. Longissimus thoracis samples were collected from carcasses (24 h post-mortem) of purebred Berkshire barrows (n=9) managed in mixed-sex pens and fed finishing diets containing ractopamine (RAC; 7.4 mg/kg for 14 days followed by 10.0 mg/kg for 14 days) or without ractopamine for 28 days (CON). Sarcoplasmic proteome was analyzed using two-dimensional electrophoresis and mass spectrometry. Nine protein spots were differentially abundant between RAC and CON groups. Glyceraldehyde-3-phosphate dehydrogenase and phosphoglucomutase-1 were over-abundant in CON, whereas serum albumin, carbonic anhydrase 3, L-lactate dehydrogenase A chain, fructose-bisphosphate aldolase A, and myosin light chain 1/3 were over-abundant in RAC. These results suggest that ractopamine influences the abundance of enzymes involved in glycolytic metabolism, and the differential abundance of glycolytic enzymes could potentially influence the conversion of muscle to meat. PMID:25576742

  20. Reappraisal of intergender differences in the urethral striated sphincter explains why a completely circular arrangement is difficult in females: a histological study using human fetuses

    PubMed Central

    Takenaka, Atsushi; Rodríguez-Vázquez, Jose Francisco; Murakami, Gen; Matsubara, Akio

    2012-01-01

    To investigate why the development of a completely circular striated sphincter is so rare, we examined histological sections of 11 female and 11 male mid-term human fetuses. In male fetuses, the striated muscle initially extended in the frontal, rather than in the horizontal plane. However, a knee-like portion was absent in the female fetal urethra because, on the inferior side of the vaginal end, a wide groove for the future vestibule opened inferiorly. Accordingly, it was difficult for the developing striated muscle to surround the groove, even though there was not a great difference in width or thickness between the female vestibule and the male urethra. The development of a completely circular striated sphincter seems to be impossible in females because of interruption of the frontal plane by the groove-like vestibule. However, we cannot rule out the possibility that before descent of the vagina, the urethral striated muscle extends posteriorly. PMID:22822461

  1. Differential abundance of sarcoplasmic proteome explains animal effect on beef Longissimus lumborum color stability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The sarcoplasmic proteome of beef Longissimus lumborum demonstrating animal-to-animal variation in color stability was examined to correlate proteome profile with color. Longissimus lumborum (36 h post-mortem) muscles were obtained from 73 beef carcasses, aged for 13 days, and fabricated to 2.5-cm s...

  2. Strategies to Study Desmin in Cardiac Muscle and Culture Systems.

    PubMed

    Diokmetzidou, Antigoni; Tsikitis, Mary; Nikouli, Sofia; Kloukina, Ismini; Tsoupri, Elsa; Papathanasiou, Stamatis; Psarras, Stelios; Mavroidis, Manolis; Capetanaki, Yassemi

    2016-01-01

    Intermediate filament (IF) cytoskeleton comprises the fine-tuning cellular machinery regulating critical homeostatic mechanisms. In skeletal and cardiac muscle, deficiency or disturbance of the IF network leads to severe pathology, particularly in the latter. The three-dimensional scaffold of the muscle-specific IF protein desmin interconnects key features of the cardiac muscle cells, including the Z-disks, intercalated disks, plasma membrane, nucleus, mitochondria, lysosomes, and potentially sarcoplasmic reticulum. This is crucial for the highly organized striated muscle, in which effective energy production and transmission as well as mechanochemical signaling are tightly coordinated among the organelles and the contractile apparatus. The role of desmin and desmin-associated proteins in the biogenesis, trafficking, and organelle function, as well as the development, differentiation, and survival of the cardiac muscle begins to be enlightened, but the precise mechanisms remain elusive. We propose a set of experimental tools that can be used, in vivo and in vitro, to unravel crucial new pathways by which the IF cytoskeleton facilitates proper organelle function, homeostasis, and cytoprotection and further understand how its disturbance and deficiency lead to disease. PMID:26795479

  3. Occurrence and Characteristics of a Rapid Exchange of Phosphate Oxygens Catalyzed by Sarcoplasmic Reticulum Vesicles

    DOE R&D Accomplishments Database

    Kanazawa, T.; Boyer, P. D.

    1972-01-01

    Sarcoplasmic reticulum vesicles isolated from skeletal muscle actively take up Ca{sup ++} from the medium in the presence of Mg{sup ++} and ATP. This transport is coupled to ATP hydrolysis catalyzed by membrane-bound Ca{sup++}, Mg{sup ++}-ATPase which is activated by concurrent presence of Ca{sup ++} and Mg{sup ++}. Considerable informations have accumulated that give insight into the ATPase and its coupling to the calcium transport. The hydrolysis of ATP by this enzyme occurs through a phosphorylated intermediate. Formation and decomposition of the intermediate show vectorial requirements for Ca{sup ++} and Mg{sup ++}, suggesting an intimate involvement of the intermediate in the transport process. ATP synthesis from P{sub i} and ADP coupled to outflow of Ca{sup ++} from sarcoplasmic reticulum vesicles has recently been demonstrated. This indicates the reversibility of the entire process of calcium transport in sarcoplasmic reticulum vesicles.

  4. Muscle Giants: Molecular Scaffolds in Sarcomerogenesis

    PubMed Central

    KONTROGIANNI-KONSTANTOPOULOS, AIKATERINI; ACKERMANN, MAEGEN A.; BOWMAN, AMBER L.; YAP, SOLOMON V.; BLOCH, ROBERT J.

    2011-01-01

    Myofibrillogenesis in striated muscles is a highly complex process that depends on the coordinated assembly and integration of a large number of contractile, cytoskeletal, and signaling proteins into regular arrays, the sarcomeres. It is also associated with the stereotypical assembly of the sarcoplasmic reticulum and the transverse tubules around each sarcomere. Three giant, muscle-specific proteins, titin (3–4 MDa), nebulin (600–800 kDa), and obscurin (~720–900 kDa), have been proposed to play important roles in the assembly and stabilization of sarcomeres. There is a large amount of data showing that each of these molecules interacts with several to many different protein ligands, regulating their activity and localizing them to particular sites within or surrounding sarcomeres. Consistent with this, mutations in each of these proteins have been linked to skeletal and cardiac myopathies or to muscular dystrophies. The evidence that any of them plays a role as a “molecular template,” “molecular blueprint,” or “molecular ruler” is less definitive, however. Here we review the structure and function of titin, nebulin, and obscurin, with the literature supporting a role for them as scaffolding molecules and the contradictory evidence regarding their roles as molecular guides in sarcomerogenesis. PMID:19789381

  5. Objective forensic analysis of striated, quasi-striated and impressed toolmarks

    NASA Astrophysics Data System (ADS)

    Spotts, Ryan E.

    Following the 1993 Daubert v. Merrell Dow Pharmaceuticals, Inc. court case and continuing to the 2010 National Academy of Sciences report, comparative forensic toolmark examination has received many challenges to its admissibility in court cases and its scientific foundations. Many of these challenges deal with the subjective nature in determining whether toolmarks are identifiable. This questioning of current identification methods has created a demand for objective methods of identification - "objective" implying known error rates and statistically reliability. The demand for objective methods has resulted in research that created a statistical algorithm capable of comparing toolmarks to determine their statistical similarity, and thus the ability to separate matching and nonmatching toolmarks. This was expanded to the creation of virtual toolmarking (characterization of a tool to predict the toolmark it will create). The statistical algorithm, originally designed for two-dimensional striated toolmarks, had been successfully applied to striated screwdriver and quasi-striated plier toolmarks. Following this success, a blind study was conducted to validate the virtual toolmarking capability using striated screwdriver marks created at various angles of incidence. Work was also performed to optimize the statistical algorithm by implementing means to ensure the algorithm operations were constrained to logical comparison regions (e.g. the opposite ends of two toolmarks do not need to be compared because they do not coincide with each other). This work was performed on quasi-striated shear cut marks made with pliers - a previously tested, more difficult application of the statistical algorithm that could demonstrate the difference in results due to optimization. The final research conducted was performed with pseudostriated impression toolmarks made with chisels. Impression marks, which are more complex than striated marks, were analyzed using the algorithm to separate

  6. Cone inputs to murine striate cortex

    PubMed Central

    Ekesten, Björn; Gouras, Peter

    2008-01-01

    Background We have recorded responses from single neurons in murine visual cortex to determine the effectiveness of the input from the two murine cone photoreceptor mechanisms and whether there is any unique selectivity for cone inputs at this higher region of the visual system that would support the possibility of colour vision in mice. Each eye was stimulated by diffuse light, either 370 (strong stimulus for the ultra-violet (UV) cone opsin) or 505 nm (exclusively stimulating the middle wavelength sensitive (M) cone opsin), obtained from light emitting diodes (LEDs) in the presence of a strong adapting light that suppressed the responses of rods. Results Single cells responded to these diffuse stimuli in all areas of striate cortex. Two types of responsive cells were encountered. One type (135/323 – 42%) had little to no spontaneous activity and responded at either the on and/or the off phase of the light stimulus with a few impulses often of relatively large amplitude. A second type (166/323 – 51%) had spontaneous activity and responded tonically to light stimuli with impulses often of small amplitude. Most of the cells responded similarly to both spectral stimuli. A few (18/323 – 6%) responded strongly or exclusively to one or the other spectral stimulus and rarely in a spectrally opponent manner. Conclusion Most cells in murine striate cortex receive excitatory inputs from both UV- and M-cones. A small fraction shows either strong selectivity for one or the other cone mechanism and occasionally cone opponent responses. Cells that could underlie chromatic contrast detection are present but extremely rare in murine striate cortex. PMID:19014590

  7. Collisionless Plasma Shocks in Striated Electron Temperatures

    SciTech Connect

    Guio, P.; Pecseli, H. L.

    2010-02-26

    The existence of low frequency waveguide modes of ion acoustic waves is demonstrated in magnetized plasmas for electron temperatures striated along the magnetic field lines. At higher frequencies, in a band between the ion cyclotron and the ion plasma frequency, radiative modes develop and propagate obliquely to the field away from the striation. Arguments for the subsequent formation and propagation of electrostatic shock are presented and demonstrated numerically. For such plasma conditions, the dissipation mechanism is the 'leakage' of the harmonics generated by the wave steepening.

  8. Effects of temperature and buffer composition on calcium sequestration by sarcoplasmic reticulum and plasma membrane of rabbit renal artery

    SciTech Connect

    McGuffee, L.J.; Little, S.A.; Mercure, J.V.; Skipper, B.J.; Wheeler-Clark, E.S. )

    1990-11-01

    45Ca electron microscopic autoradiography was used to examine the effects of buffer composition and temperature on the distribution of calcium in rabbit renal artery smooth muscle cells. The results show that the relative distribution of calcium is dependent on both the buffer used (Tris or Krebs) and the temperature of the bathing solution (25 degrees C or 34{degrees}C). Krebs buffer at 34{degrees}C gave the highest relative activity in the plasma membrane, sarcoplasmic reticulum, and mitochondria. Buffer and temperature had little effect on the relative activity of the nucleus or cytoplasm. Next, we identified the cellular sites of calcium accumulation after 5, 15, 30, or 60 min exposure to {sup 45}Ca in Krebs buffer at 34{degrees}C. The results show that sarcoplasmic reticulum and plasma membrane are the primary sites of calcium accumulation during influx into these cells. Although the amount of {sup 45}Ca in the cell continues to increase with longer exposure, the relative distribution of calcium is essentially the same after 5 or 60 min. The data also indicate that the relative activity of plasma membrane + sarcoplasmic reticulum (a combination site that includes sarcoplasmic reticulum within a mean distance of 275 nm of the plasma membrane) is similar to the membrane alone and is lower than the sarcoplasmic reticulum alone.

  9. Interrelated striated elements in vestibular hair cells of the rat

    NASA Technical Reports Server (NTRS)

    Ross, M. D.; Bourne, C.

    1983-01-01

    A series of interrelated striated organelles in types I and II vestibular hair cells of the rat which appear to be less developed in cochlear hair cells have been revealed by unusual fixation procedures, suggesting that contractile elements may play a role in sensory transduction in the inner ear, especially in the vestibular system. Included in the series of interrelated striated elements are the cuticular plate and its basal attachments to the hair cell margins, the connections of the strut array of the kinociliary basal body to the cuticular plate, and striated organelles associated with the plasma membrane and extending below the apical junctional complexes.

  10. Charge movement in the membrane of striated muscle.

    PubMed Central

    Adrian, R H; Almers, W

    1976-01-01

    1. Non-linear polarization currents apparently due to permanent dipoles or mobile charges in the membrane can be measured by appropriate comparison of the transient currents required to produce small and large steps of membrane potential. Integration of these transient polarization currents estimates the charge transfer associated with the movement of membrane dipoles or charges. 2. Depolarization from -100 to 0 mV requires a charge transfer of 35 nC/muF in addition to the charge transfer predicted by linear extrapolation of the charge required for a small depolarization from -100 mV. Depolarizations of varying size give a charge-voltage relation which is sigmoid saturating beyond o mV and with a midpoint at about -50 mV. The ratnged depolarization reduces or removes charge movement detected by comparing currents for small and large voltage steps from -100 mV (Charge 1). However in depolarized fibres comparison of currents from a small potential step at +40 mV and a large hyperpolarizing potential step from -20 mV reveals large movements of a second charge (Charge 2). Movement of Charge 2 is less steeply dependent on voltage than movement of Charge 2 both in magnitude and in rate. 4. In size and voltage dependence these two kinds of charge movement correspond to measured voltage dependence of capacity in normally polarized and depolarized fibres (Adrian & Almers, 1976). PMID:1082509

  11. Hand-Held Model of a Sarcomere to Illustrate the Sliding Filament Mechanism in Muscle Contraction

    ERIC Educational Resources Information Center

    Jittivadhna, Karnyupha; Ruenwongsa, Pintip; Panijpan, Bhinyo

    2009-01-01

    From our teaching of the contractile unit of the striated muscle, we have found limitations in using textbook illustrations of sarcomere structure and its related dynamic molecular physiological details. A hand-held model of a striated muscle sarcomere made from common items has thus been made by us to enhance students' understanding of the…

  12. Representation of the visual field in the occipital striate cortex.

    PubMed Central

    McFadzean, R; Brosnahan, D; Hadley, D; Mutlukan, E

    1994-01-01

    The representation of the field of vision in the human striate cortex is based on the Holmes map in which about 25% of the surface area of the striate cortex is allocated to the central 15 degrees of vision. Following the introduction of computed tomography of the brain, the accuracy of the Holmes map was apparently confirmed by clinical/radiological correlation, but a revision has been proposed by Horton and Hoyt based on a magnetic resonance imaging study of three patients with visual field defects due to striate lesions. They propose that the central cortical representation of vision occupies a much larger area. This study reviews the perimetric and imaging findings in a larger series of patients with striate cortical disease and provides support for the revised representation. The clinical phenomenon of macular sparing and its relation to representation of the macula at the occipital pole is also discussed. Images PMID:8148333

  13. [Electron microscopic study of striate keratosis palmoplantaris (Wachters type)].

    PubMed

    Küchmeister, B; Mahrle, G

    1985-06-15

    We report on a patient suffering from striate palmoplantar keratoderma (Wachters' type). Ultrastructural findings are presented for the first time. There was orthohyperkeratosus without alterations indicating a specific disturbance of keratinisation. PMID:2411057

  14. Evaluation of Vascular Delivery Methodologies to Enhance rAAV6-mediated Gene Transfer to Canine Striated Musculature

    PubMed Central

    Gregorevic, Paul; Schultz, Brian R; Allen, James M; Halldorson, Jeffrey B; Blankinship, Michael J; Meznarich, Norman A; Kuhr, Christian S; Doremus, Caitlin; Finn, Eric; Liggitt, Denny; Chamberlain, Jeffrey S

    2009-01-01

    A growing body of research supports the development of recombinant adeno-associated viral (rAAV) vectors for delivery of gene expression cassettes to striated musculature as a method of treating severe neuromuscular conditions. However, it is unclear whether delivery protocols that achieve extensive gene transfer in mice can be adapted to produce similarly extensive gene transfer in larger mammals and ultimately patients. Consequently, we sought to investigate methodological modifications that would facilitate rAAV-mediated gene transfer to the striated musculature of canines. A simple procedure incorporating acute (i) occlusion of limb blood flow, (ii) exsanguination via compression bandage, and (iii) vector “dwell” time of <20 minutes, markedly enhanced the transduction of limb muscles, compared with a simple bolus limb infusion of vector. A complementary method whereby vector was infused into the jugular vein led to efficient transduction of cardiomyocytes and to a lesser degree the diaphragm. Together these methods can be used to achieve transgene expression in heart, diaphragm, and limb muscles of juvenile dogs using rAAV6 vectors. These results establish that rAAV-mediated gene delivery is a viable approach to achieving systemic transduction of striated musculature in mammals approaching the dimensions of newborn humans. PMID:19471246

  15. Doxorubicin cardiomyopathy is associated with a decrease in calcium release channel of the sarcoplasmic reticulum in a chronic rabbit model.

    PubMed Central

    Dodd, D A; Atkinson, J B; Olson, R D; Buck, S; Cusack, B J; Fleischer, S; Boucek, R J

    1993-01-01

    Doxorubicin is a highly effective cancer chemotherapeutic agent that produces a dose-dependent cardiomyopathy that limits its clinical usefulness. Clinical and animal studies of morphological changes during the early stages of doxorubicin-induced cardiomyopathy have suggested that the sarcoplasmic reticulum, the intracellular membrane system responsible for myoplasmic calcium regulation in adult mammalian heart, may be the early target of doxorubicin. To detect changes in the calcium pump protein or the calcium release channel (ryanodine receptor) of the sarcoplasmic reticulum during chronic doxorubicin treatment, rabbits were treated with intravenous doxorubicin (1 mg/kg) twice weekly for 12 to 18 doses. Pair-fed controls received intravenous normal saline. The severity of cardiomyopathy was scored by light and electron microscopy of left ventricular papillary muscles. Developed tension was measured in isolated atrial strips. In subcellular fractions from heart, [3H]ryanodine binding was decreased in doxorubicin-treated rabbits (0.33 +/- 0.03 pmol/mg) compared with control rabbits (0.66 +/- 0.02 pmol/mg; P < 0.0001). The magnitude of the decrease in [3H]ryanodine binding correlated with both the severity of the cardiomyopathy graded by pathology score (light and electron microscopy) and the decrease in developed tension in isolated atrial strips. Bmax for [3H]ryanodine binding and the amount of immunoreactive ryanodine receptor by Western blot analysis using sequence-specific antibody were both decreased, consistent with a decrease in the amount of calcium release channel of sarcoplasmic reticulum in doxorubicin-treated rabbits. In contrast, there was no decrease in the amount or the activity of the calcium pump protein of the sarcoplasmic reticulum in doxorubicin-treated rabbits. Doxorubicin treatment did not decrease [3H]ryanodine binding or the amount of immunoreactive calcium release channel of sarcoplasmic reticulum in skeletal muscle. Since the sarcoplasmic

  16. A muscle stem cell for every muscle: variability of satellite cell biology among different muscle groups

    PubMed Central

    Randolph, Matthew E.; Pavlath, Grace K.

    2015-01-01

    The human body contains approximately 640 individual skeletal muscles. Despite the fact that all of these muscles are composed of striated muscle tissue, the biology of these muscles and their associated muscle stem cell populations are quite diverse. Skeletal muscles are affected differentially by various muscular dystrophies (MDs), such that certain genetic mutations specifically alter muscle function in only a subset of muscles. Additionally, defective muscle stem cells have been implicated in the pathology of some MDs. The biology of muscle stem cells varies depending on the muscles with which they are associated. Here we review the biology of skeletal muscle stem cell populations of eight different muscle groups. Understanding the biological variation of skeletal muscles and their resident stem cells could provide valuable insight into mechanisms underlying the susceptibility of certain muscles to myopathic disease. PMID:26500547

  17. Flavour formation from hydrolysis of pork sarcoplasmic protein extract by a unique LAB culture isolated from Harbin dry sausage.

    PubMed

    Chen, Qian; Liu, Qian; Sun, Qinxiu; Kong, Baohua; Xiong, Youling

    2015-02-01

    The lactic acid bacteria Pediococcus pentosaceus, Lactobacillus brevis, Lactobacillus curvatus, and Lactobacillus fermentum isolated from Harbin dry sausage were assessed for their protein hydrolysis and flavour development in pork muscle sarcoplasmic protein extracts. Gel electrophoresis indicated that sarcoplasmic proteins were degraded by all of the strains, especially by P. pentosaceus and L. curvatus. Trichloroacetic acid-soluble peptides increased in all of the samples (P < 0.05), especially samples inoculated with P. pentosaceus. Samples inoculated with P. pentosaceus and L. curvatus had higher free amino acid contents than did the other two strains(P < 0.05), and glutamic acid and alanine appeared to be the predominant free amino acids. The volatile compound analysis indicated that the highest aldehydes, alcohols and acid contents were found in the sample with P. pentosaceus followed by L. curvatus. The results revealed that P. pentosaceus could be appropriate for use as a meat starter culture. PMID:25460113

  18. Effects of tetrandrine on calcium transport, protein fluorescences and membrane fluidity of sarcoplasmic reticulum

    PubMed Central

    Chen, Lan-Ying; Chen, Xi; Tian, Xiao-Li; Yu, Xiao-Hong

    2000-01-01

    To understand whether the molecular mechanism of Tetrandrine (Tet)'s pharmacological effects is concerned with sarcoplasmic reticulum calcium transport so as to be involved in myocardial contractility, we observed the effects of Tet on calcium transport and membrane structure of rabbit skeletal muscle sarcoplasmic reticulum vesicles (SR) and rat cardiac sarcoplasmic reticulum vesicles (CSR).Calcium uptake was monitored with a dual-wavelength spectrophotometer. Protein conformation and fluorescence polarization were measured by fluospectrophotometric method and membrane lipids labelled with fluorescence probes for SR, respectively.128 μmol l−1 Tet reduced the initial rate of calcium uptake to 59% of control 6 min after reaction. Tet un-competitively inhibited SR Ca2+,Mg2+-ATPase activity, causing the stoichiometric ratio of SR Ca2+/ATP to decrease to 1.43 from 2.0 of control.Inhibitory rates on SR Ca2+,Mg2+-ATPase by Tet were reduced from 60% in the absence of phosphate to 50% in the presence of phosphate and reduced from 92% in 1 mmol l−1 ATP to 60% in 5 mmol l−1 ATP.Tet markedly reduced SR intrinsic protein fluorescence, while it slightly decreased the thiol(SH)-modified protein fluorescence of SR labelled with N-(3-pyrene)-maleimide.Tet slightly increased fluorescence polarization in the middle and deep layers of SR membrane lipids labelled with 7- or 12-(9-anthroyloxy) stearic acid (AS) probes, whereas it did not change that of SR labelled with 1,6-diphenyl-1,3,5-hexatrine (DPH).These results revealed that prevention of SR calcium uptake by Tet was due to inhibition of the SR calcium pump Ca2+,Mg2+-ATPase, changes in spatial conformation of the pumps protein molecules and a decrease in the extent of motion of membrane lipid molecules, thus altering the regulation of [Ca2+]i and myocardial contractility. PMID:11015304

  19. The sarcoplasmic Ca2+-ATPase: design of a perfect chemi-osmotic pump.

    PubMed

    Møller, Jesper V; Olesen, Claus; Winther, Anne-Marie L; Nissen, Poul

    2010-11-01

    The sarcoplasmic (SERCA 1a) Ca2+-ATPase is a membrane protein abundantly present in skeletal muscles where it functions as an indispensable component of the excitation-contraction coupling, being at the expense of ATP hydrolysis involved in Ca2+/H+ exchange with a high thermodynamic efficiency across the sarcoplasmic reticulum membrane. The transporter serves as a prototype of a whole family of cation transporters, the P-type ATPases, which in addition to Ca2+ transporting proteins count Na+, K+-ATPase and H+, K+-, proton- and heavy metal transporting ATPases as prominent members. The ability in recent years to produce and analyze at atomic (2·3-3 Å) resolution 3D-crystals of Ca2+-transport intermediates of SERCA 1a has meant a breakthrough in our understanding of the structural aspects of the transport mechanism. We describe here the detailed construction of the ATPase in terms of one membraneous and three cytosolic domains held together by a central core that mediates coupling between Ca2+-transport and ATP hydrolysis. During turnover, the pump is present in two different conformational states, E1 and E2, with a preference for the binding of Ca2+ and H+, respectively. We discuss how phosphorylated and non-phosphorylated forms of these conformational states with cytosolic, occluded or luminally exposed cation-binding sites are able to convert the chemical energy derived from ATP hydrolysis into an electrochemical gradient of Ca2+ across the sarcoplasmic reticulum membrane. In conjunction with these basic reactions which serve as a structural framework for the transport function of other P-type ATPases as well, we also review the role of the lipid phase and the regulatory and thermodynamic aspects of the transport mechanism. PMID:20809990

  20. Mechanical Properties of Respiratory Muscles

    PubMed Central

    Sieck, Gary C.; Ferreira, Leonardo F.; Reid, Michael B.; Mantilla, Carlos B.

    2014-01-01

    Striated respiratory muscles are necessary for lung ventilation and to maintain the patency of the upper airway. The basic structural and functional properties of respiratory muscles are similar to those of other striated muscles (both skeletal and cardiac). The sarcomere is the fundamental organizational unit of striated muscles and sarcomeric proteins underlie the passive and active mechanical properties of muscle fibers. In this respect, the functional categorization of different fiber types provides a conceptual framework to understand the physiological properties of respiratory muscles. Within the sarcomere, the interaction between the thick and thin filaments at the level of cross-bridges provides the elementary unit of force generation and contraction. Key to an understanding of the unique functional differences across muscle fiber types are differences in cross-bridge recruitment and cycling that relate to the expression of different myosin heavy chain isoforms in the thick filament. The active mechanical properties of muscle fibers are characterized by the relationship between myoplasmic Ca2+ and cross-bridge recruitment, force generation and sarcomere length (also cross-bridge recruitment), external load and shortening velocity (cross-bridge cycling rate), and cross-bridge cycling rate and ATP consumption. Passive mechanical properties are also important reflecting viscoelastic elements within sarcomeres as well as the extracellular matrix. Conditions that affect respiratory muscle performance may have a range of underlying pathophysiological causes, but their manifestations will depend on their impact on these basic elemental structures. PMID:24265238

  1. Modulation of Sarcoplasmic Reticulum Calcium Pump (SERCA) Function by Membrane Cholesterol during Unloading

    NASA Astrophysics Data System (ADS)

    Clarke, M. S. F.; Hammond, D. K.; Feeback, D. L.

    2002-01-01

    We have recently demonstrated by in situ immuno-localization that cholesterol is predominantly located in the sarcoplasmic reticulum (SR), rather than in the sarcolemmal/T-tubule (SL-TT) membranes of both human and rat skeletal muscle (Clarke et al., 2000, JAP). In addition, we have demonstrated that mechanical unloading of skeletal muscle in a rat hindlimb suspension model significantly increases membrane cholesterol content and that this increase is also localized to SR rather than SL-TT membranes in such atrophied muscle. Utilizing a novel fluorescent calcium staining technique in perfusion fixed soleus muscle we observed a significant positive correlation between membrane cholesterol content and free intramyofiber calcium levels during unloading. To determine if a correlation between increased SR membrane cholesterol content and increased free intramyofiber calcium levels during unloading is due to a membrane cholesterol-mediated alteration in SR calcium pump function, we also describe the effects of modulating the cholesterol content of purified SR membrane preparations on SR-Ca2+ ATPase activity and ryanodine channel activity. As an increase in free intra-cellular calcium levels have previously demonstrated to induce catabolism in a wide range of biological systems, we suggest that altered SR calcium pump function may be the underlying basis for the initiation of unloading induced muscle atrophy.

  2. Assembly of ATPase protein in sarcoplasmic reticulum membranes.

    PubMed Central

    Scales, D; Giuseppeinesi

    1976-01-01

    Three specimen preparation techniques for electron microscopy were used to investigate the incorporation of the ATPase polypeptide chains in the membranes of fragmented sarcoplasmic reticulum (SR) obtained from rabbit skeletal muscle. Observations were made of both normal vesicles and vesicles exposed to trypsin, which is known to cleave the ATPase protein and to alter the ultrastructure of the vesicles in predictable ways. Freeze-fracture replicas reveal the typical 90-A particles on the concave (PF) faces with a density of 5,730 +/- 520/mum2. On the other hand both negatively stained and deeply etched preparations display outer projections, which are absent on trypsin-incubated vesicles. The etched specimens afford for the first time top views of the vesicles in the absence of any stain. These views reveal outer projections on the PS surface with a density of 21,000 +/- 3,900/mum2, a value nearly approximating the density of the ATPase polypeptide chains (106,000 mol wt) calculated on the basis of protein and membrane area determinations. On the other hand, this value is three to four times higher than that found for the density of the 90-A particles on the concave fracture faces. Since both outer projections and 90-A particles are identified with the ATPase protein, it is suggested that the ATPase polypeptide chains are amphiphilic molecules, with polar ends protruding individually as outer projections on the surface of the vesicles, and hydrophobic ends appearing as 90-A particles on the concave fracture faces. The discrepancy between the densities of the outer projections and the 90-A particles may be attributed either to variable penetration of the polypeptide chains into the membrane bilayer, or to formation of oligomers containing three or four hydrophobic ends and appearing as single 90-A particles. Each ATPase chain forms a complex with 20-30 phospholipid molecules. The remaining phospholipids (approximately 70% of the total SR phospholipids) account for

  3. Psychophysics of electrical stimulation of striate cortex in macaques.

    PubMed

    Bartlett, John R; DeYoe, Edgar A; Doty, Robert W; Lee, Barry B; Lewine, Jeffrey D; Negrão, Nubio; Overman, William H

    2005-11-01

    Macaques indicated their detection of onset or alteration of 0.2-ms pulses applied in various configurations through electrodes implanted in striate cortex. When microelectrodes were introduced and left in place, the threshold for detection of 100-Hz pulses nearly doubled within 24 h. However, for chronically implanted platinum-alloy macroelectrodes detection thresholds usually remained stable for many months, independently of location within striate cortex or its immediately subjacent white matter. Thresholds were unaffected by the visual conditions, such as light versus darkness, or movement of the eyes; but in one animal blind after acute glaucoma thresholds for loci in striate cortex were permanently decreased by about 50%. Learning to respond to electrical stimulation of the optic tract produced no tendency to respond to such stimulation of striate cortex. Onset of stimulation at a given locus could be detected even in the face of continuous supraliminal stimulation at four surrounding loci on a 3-mm radius. The surround stimulation did alter the threshold of the central locus, but such stimuli could not summate if they were subliminal by some 10%. Cessation of stimulation that had been continuing for 1 min to 1 h could be detected if it were being applied at a level 20-75% above that needed for detection of stimulus onset. Continuous stimulation had a pronounced "priming" effect, in that modulation of frequency or intensity of such stimulation by as little as 5% could be detected (e.g., 20 microA in a background of 500 microA, or <2-ms interpulse interval with pulses at 50 Hz). Using pulses inserted in various phase relations to ongoing pulses at 2-5 Hz, it could be determined that stimulus pulses were surrounded by a strong facilitatory period for about 30 ms, which was then replaced by refractoriness. Given the congruence of macaque and human visual anatomy and psychophysics, these results further encourage efforts to develop a cortical prosthesis for the

  4. Abnormal expression of the calmodulin gene in muscle from the dystrophic chicken

    SciTech Connect

    Hudecki, M.S.; Kibler, P.K.; Pollina, C.M.; Thacore, H.R.; Davis, P.J.; Davis, F.B.

    1986-05-29

    Compared to that of genetically-related normal chickens, pectoralis muscle from the dystrophic chicken contained increased calmodulin measured by radioimmunoassay. Determined by the dot blot procedure, expression of the calmodulin gene was enhanced in muscle from affected animals. The bioactivity of the gene product was normal. Together with previous studies reporting of increased sarcoplasmic calmodulin suggest the latter is a cellular response to defective Ca/sup 2 +/ transport at the level of cell efflux or intracellular organelle (sarcoplasmic reticulum) uptake.

  5. Deoxyglucose Analysis of Retinotopic Organization in Primate Striate Cortex

    NASA Astrophysics Data System (ADS)

    Tootell, Roger B. H.; Silverman, Martin S.; Switkes, Eugene; de Valois, Russell L.

    1982-11-01

    We have anatomically analyzed retinotopic organization using the 14C-labeled 2-deoxy-D-glucose method. The method has several advantages over conventional electrophysiological mapping techniques. In the striate cortex, the anatomical substrate for retinotopic organization is suprisingly well ordered, and there seems to be a systematic relationship between ocular dominance strips and cortical magnification. The 2-deoxyglucose maps in this area appear to be largely uninfluenced by known differences in long-term metabolic activity. This method should prove useful in analyzing retinotopic organization in various visual areas of the brain and in different species.

  6. Virtual and simulated striated toolmarks for forensic applications.

    PubMed

    Baiker, Martin; Petraco, Nicholas D K; Gambino, Carol; Pieterman, René; Shenkin, Peter; Zoon, Peter

    2016-04-01

    Large numbers of experimental toolmarks of screwdrivers are often required in casework of toolmark examiners and in research environments alike, to be able to recover the angle of attack of a crime scene mark and to determine statistically meaningful properties of toolmarks respectively. However, in practice the number of marks is limited by the time needed to create them. In this article, we present an approach to predict how a striated mark of a particular tool would look like, using 3D surface datasets of screwdrivers. We compare these virtual toolmarks qualitatively and quantitatively with real experimental marks in wax and show that they are very similar. In addition we study toolmark similarity, dependent on the angle of attack, with a very high angular resolution of 1°. The results show that for the tested type of screwdriver, our toolmark comparison framework yields known match similarity scores that are above the mean known non-match similarity scores, even for known match differences in angle of attack of up to 40°. In addition we demonstrate an approach to automatically recover the angle of attack of an experimental toolmark and experiments yield high accuracy and precision of 0.618 ± 4.179°. Furthermore, we present a strategy to study the structural elements of striated toolmarks using wavelet analysis, and show how to use the results to simulate realistic toolmarks. PMID:26874738

  7. Allergic Interstitial Nephritis Manifesting as a Striated Nephrogram

    PubMed Central

    Moinuddin, Irfan; Bracamonte, Erika; Thajudeen, Bijin; Sussman, Amy; Madhrira, Machaiah; Costello, James

    2015-01-01

    Allergic interstitial nephritis (AIN) is an underdiagnosed cause of acute kidney injury (AKI). Guidelines suggest that AIN should be suspected in a patient who presents with an elevated serum creatinine and a urinalysis that shows white cells, white cell casts, or eosinophiluria. Drug-induced AIN is suspected if AKI is temporally related to the initiation of a new drug. However, patients with bland sediment and normal urinalysis can also have AIN. Currently, a definitive diagnosis of AIN is made by renal biopsy which is invasive and fraught with risks such as bleeding, infection, and hematoma. Additionally, it is frequently unclear when a kidney biopsy should be undertaken. We describe a biopsy proven case of allergic interstitial nephritis which manifested on contrast enhanced Magnetic Resonance Imaging (MRI) as a striated nephrogram. Newer and more stable macrocyclic gadolinium contrast agents have a well-demonstrated safety profile. Additionally, in the presentation of AKI, gadolinium contrast agents are safe to administer in patients who demonstrate good urine output and a downtrending creatinine. We propose that the differential for a striated nephrogram may include AIN. In cases in which the suspicion for AIN is high, this diagnostic consideration may be further characterized by contrast enhanced MRI. PMID:26664405

  8. [Physiological functions of endoplasmic and sarcoplasmic reticulum Ca pump and pharmacology of inhibitors of the pump].

    PubMed

    Watanabe, M; Shigekawa, M

    1993-09-01

    This review is derived from the symposium held at the 66th Annual Meeting of the Japanese Pharmacological Society (March, 1993). The symposium consisted of six invited papers whose general theme was the application of recently found ATPase inhibitors selective to SR- and ER-Ca(2+)-ATPase to the analyses of the physiological and pharmacological roles of endoplasmic and sarcoplasmic reticulum Ca stores. Inhibitors used were: thapsigargin, cyclopiazonic acid, 2,5-di-(t-butyl)-1,4-benzohydroquinone and 3',3",5',5"-tetraiodosulfophthalein. Gingerol was found to facilitate the action of the ATPase. In either smooth, cardiac or skeletal muscle, sympathetic neurons or several cell lines these inhibitors affected a variety of cell functions and conditions such as contraction, ionic conductance and excitability of the plasma membrane, regulation of intracellular free Ca2+ concentration, transport of viral glycoprotein to the cell surface. Many of these studies utilized either single or cultured cell preparations or skinned muscle. These inhibitors were shown to be useful tools for investigating the SR and ER functioning as Ca sources or Ca sequestrating pumps, and further for estimating the contribution of ER or SR to regulating the flux of Ca2+ and other ions through the plasma membrane. Results of analyses using these inhibitors are discussed. PMID:8406230

  9. Myotonic dystrophy protein kinase phosphorylates phospholamban and regulates calcium uptake in cardiomyocyte sarcoplasmic reticulum.

    PubMed

    Kaliman, Perla; Catalucci, Daniele; Lam, Jason T; Kondo, Richard; Gutiérrez, José Carlos Paz; Reddy, Sita; Palacín, Manuel; Zorzano, Antonio; Chien, Kenneth R; Ruiz-Lozano, Pilar

    2005-03-01

    Myotonic dystrophy (DM) is caused by a CTG expansion in the 3'-untranslated region of a protein kinase gene (DMPK). Cardiovascular disease is one of the most prevalent causes of death in DM patients. Electrophysiological studies in cardiac muscles from DM patients and from DMPK(-/-) mice suggested that DMPK is critical to the modulation of cardiac contractility and to the maintenance of proper cardiac conduction activity. However, there are no data regarding the molecular signaling pathways involved in DM heart failure. Here we show that DMPK expression in cardiac myocytes is highly enriched in the sarcoplasmic reticulum (SR) where it colocalizes with the ryanodine receptor and phospholamban (PLN), a muscle-specific SR Ca(2+)-ATPase (SERCA2a) inhibitor. Coimmunoprecipitation studies showed that DMPK and PLN can physically associate. Furthermore, purified wild-type DMPK, but not a kinase-deficient mutant (K110A DMPK), phosphorylates PLN in vitro. Subsequent studies using the DMPK(-/-) mice demonstrated that PLN is hypo-phosphorylated in SR vesicles from DMPK(-/-) mice compared with wild-type mice both in vitro and in vivo. Finally, we show that Ca(2+) uptake in SR is impaired in ventricular homogenates from DMPK(-/-) mice. Together, our data suggest the existence of a novel regulatory DMPK pathway for cardiac contractility and provide a molecular mechanism for DM heart pathology. PMID:15598648

  10. Proteomics Unveils Fibroblast-Cardiomyocyte Lactate Shuttle and Hexokinase Paradox in Mouse Muscles.

    PubMed

    Rakus, Dariusz; Gizak, Agnieszka; Wiśniewski, Jacek R

    2016-08-01

    Quantitative mapping, given in biochemically interpretable units such as mol per mg of total protein, of tissue-specific proteomes is prerequisite for the analysis of any process in cells. We applied label- and standard-free proteomics to characterize three types of striated muscles: white, red, and cardiac muscle. The analysis presented here uncovers several unexpected and novel features of striated muscles. In addition to differences in protein expression levels, the three muscle types substantially differ in their patterns of basic metabolic pathways and isoforms of regulatory proteins. Importantly, some of the conclusions drawn on the basis of our results, such as the potential existence of a "fibroblast-cardiomyocyte lactate shuttle" and the "hexokinase paradox" point to the necessity of reinterpretation of some basic aspects of striated muscle metabolism. The data presented here constitute a powerful database and a resource for future studies of muscle physiology and for the design of pharmaceutics for the treatment of muscular disorders. PMID:27302655

  11. Weakly nonlinear ion waves in striated electron temperatures

    NASA Astrophysics Data System (ADS)

    Guio, P.; Pécseli, H. L.

    2016-04-01

    The existence of low-frequency waveguide modes of electrostatic ion acoustic waves is demonstrated in magnetized plasmas for cases where the electron temperature is striated along magnetic field lines. For low frequencies, the temperature striation acts as waveguide that supports a trapped mode. For conditions where the ion cyclotron frequency is below the ion plasma frequency we find a dispersion relation having also a radiative frequency band, where waves can escape from the striation. Arguments for the formation and propagation of an equivalent of electrostatic shocks are presented and demonstrated numerically for these conditions. The shock represents here a balance between an external energy input maintained by ion injection and a dissipation mechanism in the form of energy leakage of the harmonics generated by nonlinear wave steepening. This is a reversible form for energy loss that can replace the time-irreversible losses in a standard Burgers equation.

  12. On the water-holding of myofibrils: Effect of sarcoplasmic protein denaturation.

    PubMed

    Liu, Jiao; Arner, Anders; Puolanne, Eero; Ertbjerg, Per

    2016-09-01

    The role of heat-denatured sarcoplasmic proteins in water-holding is not well understood. Here we propose a new hypothesis that in PSE-like conditions denatured sarcoplasmic proteins aggregate within and outside myofilaments, improving the water-holding of denatured myofibrils. The process is compartmentalized: 1) within the filaments the denatured sarcoplasmic proteins shrink the lattice space and water is expelled; and 2) between the myofibrils and in the extracellular space, the coagulated sarcoplasmic proteins trap the expelled water from interfilamental space. The effect of sarcoplasmic proteins on the water-holding of myofibrils following incubation for 1h at 21 to 44°C was investigated. Our results were consistent with the new hypothesis. Myofibrils without sarcoplasm had the poorest water-holding. With increasing amount of denatured sarcoplasmic proteins, the water-holding of heat-denatured myofibrils improved proportionally. X-ray diffraction was used to measure the lattice space between the filaments. Precipitated sarcoplasmic proteins shrank (P<0.001) the lattice spacing by 6.3% at 44°C. PMID:27129081

  13. Trimeric intracellular cation channels and sarcoplasmic/endoplasmic reticulum calcium homeostasis.

    PubMed

    Zhou, Xinyu; Lin, Peihui; Yamazaki, Daiju; Park, Ki Ho; Komazaki, Shinji; Chen, S R Wayne; Takeshima, Hiroshi; Ma, Jianjie

    2014-02-14

    Trimeric intracellular cation channels (TRIC) represents a novel class of trimeric intracellular cation channels. Two TRIC isoforms have been identified in both the human and the mouse genomes: TRIC-A, a subtype predominantly expressed in the sarcoplasmic reticulum (SR) of muscle cells, and TRIC-B, a ubiquitous subtype expressed in the endoplasmic reticulum (ER) of all tissues. Genetic ablation of either TRIC-A or TRIC-B leads to compromised K(+) permeation and Ca(2+) release across the SR/ER membrane, supporting the hypothesis that TRIC channels provide a counter balancing K(+) flux that reduces SR/ER membrane depolarization for maintenance of the electrochemical gradient that drives SR/ER Ca(2+) release. TRIC-A and TRIC-B seem to have differential functions in Ca(2+) signaling in excitable and nonexcitable cells. Tric-a(-/-) mice display defective Ca(2+) sparks and spontaneous transient outward currents in arterial smooth muscle and develop hypertension, in addition to skeletal muscle dysfunction. Knockout of TRIC-B results in abnormal IP3 receptor-mediated Ca(2+) release in airway epithelial cells, respiratory defects, and neonatal lethality. Double knockout mice lacking both TRIC-A and TRIC-B show embryonic lethality as a result of cardiac arrest. Such an aggravated lethality indicates that TRIC-A and TRIC-B share complementary physiological functions in Ca(2+) signaling in embryonic cardiomyocytes. Tric-a(-/-) and Tric-b(+/-) mice are viable and susceptible to stress-induced heart failure. Recent evidence suggests that TRIC-A directly modulates the function of the cardiac ryanodine receptor 2 Ca(2+) release channel, which in turn controls store-overload-induced Ca(2+) release from the SR. Thus, the TRIC channels, in addition to providing a countercurrent for SR/ER Ca(2+) release, may also function as accessory proteins that directly modulate the ryanodine receptor/IP3 receptor channel functions. PMID:24526676

  14. Microdomains of endoplasmic reticulum within the sarcoplasmic reticulum of skeletal myofibers

    SciTech Connect

    Kaakinen, Mika; Papponen, Hinni; Metsikkoe, Kalervo

    2008-01-15

    The relationship between the endoplasmic reticulum (ER) and the sarcoplasmic reticulum (SR) of skeletal muscle cells has remained obscure. In this study, we found that ER- and SR-specific membrane proteins exhibited diverse solubility properties when extracted with mild detergents. Accordingly, the major SR-specific protein Ca{sup 2+}-ATPase (SERCA) remained insoluble in Brij 58 and floated in sucrose gradients while typical ER proteins were partially or fully soluble. Sphingomyelinase treatment rendered SERCA soluble in Brij 58. Immunofluorescence staining for resident ER proteins revealed dispersed dots over I bands contrasting the continuous staining pattern of SERCA. Infection of isolated myofibers with enveloped viruses indicated that interfibrillar protein synthesis occurred. Furthermore, we found that GFP-tagged Dad1, able to incorporate into the oligosaccharyltransferase complex, showed the dot-like structures but the fusion protein was also present in membranes over the Z lines. This behaviour mimics that of cargo proteins that accumulated over the Z lines when blocked in the ER. Taken together, the results suggest that resident ER proteins comprised Brij 58-soluble microdomains within the insoluble SR membrane. After synthesis and folding in the ER-microdomains, cargo proteins and non-incorporated GFP-Dad1 diffused into the Z line-flanking compartment which likely represents the ER exit sites.

  15. Triadin Deletion Induces Impaired Skeletal Muscle Function*

    PubMed Central

    Oddoux, Sarah; Brocard, Julie; Schweitzer, Annie; Szentesi, Peter; Giannesini, Benoit; Brocard, Jacques; Fauré, Julien; Pernet-Gallay, Karine; Bendahan, David; Lunardi, Joël; Csernoch, Laszlo; Marty, Isabelle

    2009-01-01

    Triadin is a multiple proteins family, some isoforms being involved in muscle excitation-contraction coupling, and some having still unknown functions. To obtain clues on triadin functions, we engineered a triadin knock-out mouse line and characterized the physiological effect of triadin ablation on skeletal muscle function. These mice presented a reduced muscle strength, which seemed not to alter their survival and has been characterized in the present work. We first checked in these mice the expression level of the different proteins involved in calcium homeostasis and observed in fast muscles an increase in expression of dihydropyridine receptor, with a large reduction in calsequestrin expression. Electron microscopy analysis of KO muscles morphology demonstrated the presence of triads in abnormal orientation and a reduction in the sarcoplasmic reticulum terminal cisternae volume. Using calcium imaging on cultured myotubes, we observed a reduction in the total amount of calcium stored in the sarcoplasmic reticulum. Physiological studies have been performed to evaluate the influence of triadin deletion on skeletal muscle function. Muscle strength has been measured both on the whole animal model, using hang test or electrical stimulation combined with NMR analysis and strength measurement, or on isolated muscle using electrical stimulation. All the results obtained demonstrate an important reduction in muscle strength, indicating that triadin plays an essential role in skeletal muscle function and in skeletal muscle structure. These results indicate that triadin alteration leads to the development of a myopathy, which could be studied using this new animal model. PMID:19843516

  16. High skeletal muscle adenylate cyclase in malignant hyperthermia.

    PubMed Central

    Willner, J H; Cerri, C G; Wood, D S

    1981-01-01

    Malignant hyperthermia occurs in humans with several congenital myopathies, usually in response to general anesthesia. Commonly, individuals who develop this syndrome lack symptoms of muscle disease, and their muscle lacks specific pathological changes. A biochemical marker for this myopathy has not previously been available; we found activity of adenylate cyclase and content of cyclic AMP to be abnormally high in skeletal muscle. Secondary modification of protein phosphorylation could explain observed abnormalities of phosphorylase activation and sarcoplasmic reticulum function. PMID:6271806

  17. Role of glucocorticoids in the response of rat leg muscles to reduced activity

    NASA Technical Reports Server (NTRS)

    Jaspers, Stephen R.; Tischler, Marc E.

    1986-01-01

    Adrenalectomy did not prevent atrophy of rat soleus muscle during 6 days of tail cast suspension. Cortisol treatment enhanced the atrophy and caused atrophy of the weight-bearing soleus and both extensor digitorum longus (EDL) muscles. Unloading led to increased sarcoplasmic protein concentration in the soleus but cortisol administration increased the myhofibrillar (+stromal) protein concentration in both muscles. Suspension of hindlimbs of adrenalectomized animals led to faster protein degradation, slower sarcoplasmic protein degradation, and faster myofibrillar protein synthesis in the isolated soleus, whereas with cortisol-treated animals, the difference in synthesis of myofibrillar proteins was enhanced and that of sarcoplasmic proteins was abolished. Both soleus and EDL of suspended, cortisol-treated animals showed faster protein degradation. It is unlikely that any elevation in circulating glucocorticoids was solely responsible for atrophy of the soleus in this model, but catabolic amounts of glucocorticoids could alter the response of muscle to unloading.

  18. Neuronal basis of perceptual learning in striate cortex

    PubMed Central

    Ren, Zhen; Zhou, Jiawei; Yao, Zhimo; Wang, Zhengchun; Yuan, Nini; Xu, Guangwei; Wang, Xuan; Zhang, Bing; Hess, Robert F.; Zhou, Yifeng

    2016-01-01

    It is well known that, in humans, contrast sensitivity training at high spatial frequency (SF) not only leads to contrast sensitivity improvement, but also results in an improvement in visual acuity as assessed with gratings (direct effect) or letters (transfer effect). However, the underlying neural mechanisms of this high spatial frequency training improvement remain to be elucidated. In the present study, we examined four properties of neurons in primary visual cortex (area 17) of adult cats that exhibited significantly improved acuity after contrast sensitivity training with a high spatial frequency grating and those of untrained control cats. We found no difference in neuronal contrast sensitivity or tuning width (Width) between the trained and untrained cats. However, the trained cats showed a displacement of the cells’ optimal spatial frequency (OSF) to higher spatial frequencies as well as a larger neuronal signal-to-noise ratio (SNR). Furthermore, both the neuronal differences in OSF and SNR were significantly correlated with the improvement of acuity measured behaviorally. These results suggest that striate neurons might mediate the perceptual learning-induced improvement for high spatial frequency stimuli by an alteration in their spatial frequency representation and by an increased SNR. PMID:27094565

  19. Spatially congruent model for the striate visual cortex

    NASA Astrophysics Data System (ADS)

    da Fontoura Costa, Luciano

    1994-05-01

    A spatially congruent new model for the striate visual cortex (SVC) is proposed which accounts for some of the known functional and organizational properties of the superior mammalian SVC. Even though there is a broad consensus that the topographical representation of the visual field is one of the principal structuring principles underlying the SVC organization, the orientation maps in the SVC have often been described as non-topographical maps. In the present model, the adopted foot-of-normal representation of straight lines has allowed full congruency between the visual field topographic map and the orientation maps in the SVC. The proposed computational model includes three neural layers and assumes that the ocular dominance columns are already established at birth; three possibilities of neural mechanisms leading to orientation encoding are outlined and discussed. The model provides reasonable explanation to some of the most intriguing recently verified properties of the SVC such as the increased neural activity at the cytochrome oxidase blobs, the reduced orientation selectivity at these same places, and the pinwheel-like organization of the orientation selectivity in the SVC.

  20. Contrasting effects of strabismic amblyopia on metabolic activity in superficial and deep layers of striate cortex.

    PubMed

    Adams, Daniel L; Economides, John R; Horton, Jonathan C

    2015-05-01

    To probe the mechanism of visual suppression, we have raised macaques with strabismus by disinserting the medial rectus muscle in each eye at 1 mo of age. Typically, this operation produces a comitant, alternating exotropia with normal acuity in each eye. Here we describe an unusual occurrence: the development of severe amblyopia in one eye of a monkey after induction of exotropia. Shortly after surgery, the animal demonstrated a strong fixation preference for the left eye, with apparent suppression of the right eye. Later, behavioral testing showed inability to track or to saccade to targets with the right eye. With the left eye occluded, the animal demonstrated no visually guided behavior. Optokinetic nystagmus was absent in the right eye. Metabolic activity in striate cortex was assessed by processing the tissue for cytochrome oxidase (CO). Amblyopia caused loss of CO in one eye's rows of patches, presumably those serving the blind eye. Layers 4A and 4B showed columns of reduced CO, in register with pale rows of patches in layer 2/3. Layers 4C, 5, and 6 also showed columns of CO activity, but remarkably, comparison with more superficial layers showed a reversal in contrast. In other words, pale CO staining in layers 2/3, 4A, and 4B was aligned with dark CO staining in layers 4C, 5, and 6. No experimental intervention or deprivation paradigm has been reported previously to produce opposite effects on metabolic activity in layers 2/3, 4A, and 4B vs. layers 4C, 5, and 6 within a given eye's columns. PMID:25810480

  1. Contrasting effects of strabismic amblyopia on metabolic activity in superficial and deep layers of striate cortex

    PubMed Central

    Adams, Daniel L.; Economides, John R.

    2015-01-01

    To probe the mechanism of visual suppression, we have raised macaques with strabismus by disinserting the medial rectus muscle in each eye at 1 mo of age. Typically, this operation produces a comitant, alternating exotropia with normal acuity in each eye. Here we describe an unusual occurrence: the development of severe amblyopia in one eye of a monkey after induction of exotropia. Shortly after surgery, the animal demonstrated a strong fixation preference for the left eye, with apparent suppression of the right eye. Later, behavioral testing showed inability to track or to saccade to targets with the right eye. With the left eye occluded, the animal demonstrated no visually guided behavior. Optokinetic nystagmus was absent in the right eye. Metabolic activity in striate cortex was assessed by processing the tissue for cytochrome oxidase (CO). Amblyopia caused loss of CO in one eye's rows of patches, presumably those serving the blind eye. Layers 4A and 4B showed columns of reduced CO, in register with pale rows of patches in layer 2/3. Layers 4C, 5, and 6 also showed columns of CO activity, but remarkably, comparison with more superficial layers showed a reversal in contrast. In other words, pale CO staining in layers 2/3, 4A, and 4B was aligned with dark CO staining in layers 4C, 5, and 6. No experimental intervention or deprivation paradigm has been reported previously to produce opposite effects on metabolic activity in layers 2/3, 4A, and 4B vs. layers 4C, 5, and 6 within a given eye's columns. PMID:25810480

  2. Receptive fields of simple cells in the cat striate cortex

    PubMed Central

    Bishop, P. O.; Coombs, J. S.; Henry, G. H.

    1973-01-01

    1. The excitatory and inhibitory components in the receptive fields of unimodal simple cells in the striate cortex of the cat anaesthetized with nitrous oxide have been described using slits of light and single light-dark edges as stimuli. 2. There is a small excitatory region (excitatory complex) centrally located in the receptive field that is made up of various combinations and spatial arrangements of subliminal excitatory and discharge subregions or centres. 3. The subliminal excitatory centres were revealed by a binocular facilitation technique. The excitability of the cell was raised by repeated stimulation via one eye while the neurone was tested with single edges via the other eye. 4. The subliminal excitatory and discharge centres are each specifically activated by only one type of edge, light-dark or dark-light, and then only in one direction of motion. All the subregions in the excitatory complex have the same optimal stimulus orientation. 5. Inhibitory components in the receptive field were identified by stimulating the cell with bars of light and single edges against an artificial background discharge produced by repeated stimulation separately applied either to the same eye (monocular conditioning) or to the other eye (binocular conditioning). There are powerful inhibitory sidebands to either side of the excitatory complex and these inhibitory regions merge to include the excitatory complex when stimulus orientation is angled away from the optimal. 6. Excitation is highly stimulus specific whereas inhibition is non-specific. 7. The organization of the two receptive fields of a binocularly discharged cell can be closely similar. 8. The attempt is made to translate the concept of subliminal excitatory and discharge centres into specific neural mechanisms involving both the geniculo-cortical input and various intracortical circuits. 9. These new developments call for only minor modifications to the model we have proposed for the organization of the

  3. Orientation selectivity, preference, and continuity in monkey striate cortex.

    PubMed

    Blasdel, G G

    1992-08-01

    Maps of orientation preference and selectivity, inferred from differential images of orientation (Blasdel, 1992), reveal linear organizations in patches, 0.5-1.0 mm across, where orientation selectivities are high, and where preferred orientations rotate linearly along one axis while remaining constant along the other. Most of these linear zones lie between the centers of adjacent ocular dominance columns, with their short iso-orientation slabs oriented perpendicular, in regions enjoying the greatest binocular overlap. These two-dimensional linear zones are segregated by one- and zero-dimensional discontinuities that are particularly abundant in the centers of ocular dominance columns, and that are also correlated with cytochrome oxidase-rich zones within them. Discontinuities smaller than 90 degrees extend in one dimension, as fractures, while discontinuities greater than 90 degrees are confined to points, in the form of singularities, that are generated when orientation preferences rotate continuously through +/- 180 degrees along circular paths. The continuous rotations through 180 degrees imply that direction preferences are not organized laterally in striate cortex. And they also ensure that preferences for all orientations converge at each singularity, with perpendicular orientations represented uniquely close together on opposite sides. The periodic interspersing of linear zones and singularities suggests that orientation preferences are organized by at least two competing schemes. They are optimized for linearity, along with selectivity and binocularity, in the linear zones, and they are optimized for density near singularities. Since upper-layer neurons are likely to have similarly sized dendritic fields in all regions (Lund and Yoshioka, 1991), those in the linear zones should receive precise information about narrowly constrained orientations, while those near singularities should receive coarse information about all orientations--very different inputs

  4. In Vivo Fusion of Circulating Fluorescent Cells with Dystrophin-Deficient Myofibers Results in Extensive Sarcoplasmic Fluorescence Expression but Limited Dystrophin Sarcolemmal Expression

    PubMed Central

    Chretien, Fabrice; Dreyfus, Patrick A.; Christov, Christo; Caramelle, Philippe; Lagrange, Jean-Léon; Chazaud, Bénédicte; Gherardi, Romain K.

    2005-01-01

    To investigate the therapeutic potential of bone marrow transplantation in Duchenne muscular dystrophy, green fluorescent protein-positive (GFP+) bone marrow cells were transplanted into irradiated wild-type and dystrophin-deficient mdx mice. Tibialis anterior muscles showed fivefold to sixfold more GFP+ mononucleated cells and threefold to fourfold more GFP+ myofibers in mdx than in wild-type mice. In contrast, dystrophin expression in mdx mice remained within the level of nontransplanted mdx mice, and co-expression with GFP was rare. Longitudinal sections of 5000 myofibers showed 160 GFP+ fibers, including 9 that co-expressed dystrophin. GFP was always visualized as full-length sarcoplasmic fluorescence that exceeded the span of sample length (up to 1500 μm), whereas dystrophin expression was restricted to 11 to 28% of this length. Dystrophin expression span was much shorter in GFP+ fibers (116 ± 46 μm) than in revertant fibers (654 ± 409 μm). These data suggest that soluble GFP diffuses far from the fusion site with a pre-existing dystrophin− myofiber whereas dystrophin remains mainly expressed close to the site of fusion. Because restoration of dystrophin in whole muscle fiber length is required to expect functional improvement and clinical benefits for Duchenne muscular dystrophy, future applications of cell therapies to neuromuscular disorders could be more appropriately envisaged for replacement of defective soluble sarcoplasmic proteins. PMID:15920159

  5. Ryanodine receptor fragmentation and sarcoplasmic reticulum Ca2+ leak after one session of high-intensity interval exercise.

    PubMed

    Place, Nicolas; Ivarsson, Niklas; Venckunas, Tomas; Neyroud, Daria; Brazaitis, Marius; Cheng, Arthur J; Ochala, Julien; Kamandulis, Sigitas; Girard, Sebastien; Volungevičius, Gintautas; Paužas, Henrikas; Mekideche, Abdelhafid; Kayser, Bengt; Martinez-Redondo, Vicente; Ruas, Jorge L; Bruton, Joseph; Truffert, Andre; Lanner, Johanna T; Skurvydas, Albertas; Westerblad, Håkan

    2015-12-15

    High-intensity interval training (HIIT) is a time-efficient way of improving physical performance in healthy subjects and in patients with common chronic diseases, but less so in elite endurance athletes. The mechanisms underlying the effectiveness of HIIT are uncertain. Here, recreationally active human subjects performed highly demanding HIIT consisting of 30-s bouts of all-out cycling with 4-min rest in between bouts (≤3 min total exercise time). Skeletal muscle biopsies taken 24 h after the HIIT exercise showed an extensive fragmentation of the sarcoplasmic reticulum (SR) Ca(2+) release channel, the ryanodine receptor type 1 (RyR1). The HIIT exercise also caused a prolonged force depression and triggered major changes in the expression of genes related to endurance exercise. Subsequent experiments on elite endurance athletes performing the same HIIT exercise showed no RyR1 fragmentation or prolonged changes in the expression of endurance-related genes. Finally, mechanistic experiments performed on isolated mouse muscles exposed to HIIT-mimicking stimulation showed reactive oxygen/nitrogen species (ROS)-dependent RyR1 fragmentation, calpain activation, increased SR Ca(2+) leak at rest, and depressed force production due to impaired SR Ca(2+) release upon stimulation. In conclusion, HIIT exercise induces a ROS-dependent RyR1 fragmentation in muscles of recreationally active subjects, and the resulting changes in muscle fiber Ca(2+)-handling trigger muscular adaptations. However, the same HIIT exercise does not cause RyR1 fragmentation in muscles of elite endurance athletes, which may explain why HIIT is less effective in this group. PMID:26575622

  6. Ryanodine receptor fragmentation and sarcoplasmic reticulum Ca2+ leak after one session of high-intensity interval exercise

    PubMed Central

    Place, Nicolas; Ivarsson, Niklas; Venckunas, Tomas; Neyroud, Daria; Brazaitis, Marius; Cheng, Arthur J.; Ochala, Julien; Kamandulis, Sigitas; Girard, Sebastien; Volungevičius, Gintautas; Paužas, Henrikas; Mekideche, Abdelhafid; Kayser, Bengt; Martinez-Redondo, Vicente; Bruton, Joseph; Truffert, Andre; Lanner, Johanna T.; Skurvydas, Albertas; Westerblad, Håkan

    2015-01-01

    High-intensity interval training (HIIT) is a time-efficient way of improving physical performance in healthy subjects and in patients with common chronic diseases, but less so in elite endurance athletes. The mechanisms underlying the effectiveness of HIIT are uncertain. Here, recreationally active human subjects performed highly demanding HIIT consisting of 30-s bouts of all-out cycling with 4-min rest in between bouts (≤3 min total exercise time). Skeletal muscle biopsies taken 24 h after the HIIT exercise showed an extensive fragmentation of the sarcoplasmic reticulum (SR) Ca2+ release channel, the ryanodine receptor type 1 (RyR1). The HIIT exercise also caused a prolonged force depression and triggered major changes in the expression of genes related to endurance exercise. Subsequent experiments on elite endurance athletes performing the same HIIT exercise showed no RyR1 fragmentation or prolonged changes in the expression of endurance-related genes. Finally, mechanistic experiments performed on isolated mouse muscles exposed to HIIT-mimicking stimulation showed reactive oxygen/nitrogen species (ROS)-dependent RyR1 fragmentation, calpain activation, increased SR Ca2+ leak at rest, and depressed force production due to impaired SR Ca2+ release upon stimulation. In conclusion, HIIT exercise induces a ROS-dependent RyR1 fragmentation in muscles of recreationally active subjects, and the resulting changes in muscle fiber Ca2+-handling trigger muscular adaptations. However, the same HIIT exercise does not cause RyR1 fragmentation in muscles of elite endurance athletes, which may explain why HIIT is less effective in this group. PMID:26575622

  7. Calcium Movements Inside the Sarcoplasmic Reticulum of Cardiac Myocytes

    PubMed Central

    Bers, Donald M.; Shannon, Thomas R.

    2013-01-01

    Sarcoplasmic reticulum (SR) Ca content ([Ca]SRT) is critical to both normal cardiac function and electrophysiology, and changes associated with pathology contribute to systolic and diastolic dysfunction and arrhythmias. The intra-SR free [Ca] ([Ca]SR) dictates the [Ca]SRT, the driving force for Ca release and regulates release channel gating. We discuss measurement of [Ca]SR and [Ca]SRT, how [Ca]SR regulates activation and termination of release, and how Ca diffuses within the SR and influences SR Ca release during excitation-contraction coupling, Ca sparks and Ca waves. The entire SR network is connected and its lumen is also continuous with the nuclear envelope. Rapid Ca diffusion within the SR could stabilize and balance local [Ca]SR within the myocyte, but restrictions to diffusion can create spatial inhomogeneities. Experimental measurements and mathematical models of [Ca]SR to date have greatly enriched our understanding of these [Ca]SR dynamics, but controversies exist and may stimulate new measurements and analysis. PMID:23321551

  8. Bioactive electrospun fish sarcoplasmic proteins as a drug delivery system.

    PubMed

    Stephansen, Karen; Chronakis, Ioannis S; Jessen, Flemming

    2014-10-01

    Nano-microfibers were made from cod (Gadus morhua) sarcoplasmic proteins (FSP) (Mw<200kDa) using the electrospinning technique. The FSP fibers were studied by scanning electron microscopy, and the fiber morphology was found to be strongly dependent on FSP concentration. Interestingly, the FSP fibers were insoluble in water. However, when exposed to proteolytic enzymes, the fibers were degraded. The degradation products of the FSP fibers proved to be inhibitors of the diabetes-related enzyme DPP-IV. The FSP fibers may have biomedical applications, among others as a delivery system. To demonstrate this, a dipeptide (Ala-Trp) was encapsulated into the FSP fibers, and the release properties were investigated in gastric buffer and in intestinal buffer. The release profile showed an initial burst release, where 30% of the compound was released within the first minute, after which an additional 40% was released (still exponential) within the next 30min (gastric buffer) or 15min (intestinal buffer). The remaining 30% was not released in the timespan of the experiment. PMID:25033436

  9. Aldolase potentiates DIDS activation of the ryanodine receptor in rabbit skeletal sarcoplasmic reticulum.

    PubMed

    Seo, In-Ra; Moh, Sang Hyun; Lee, Eun Hui; Meissner, Gerhard; Kim, Do Han

    2006-10-15

    DIDS (4,4'-di-isothiocyanostilbene-2,2'-disulfonate), an anion channel blocker, triggers Ca2+ release from skeletal muscle SR (sarcoplasmic reticulum). The present study characterized the effects of DIDS on rabbit skeletal single Ca2+-release channel/RyR1 (ryanodine receptor type 1) incorporated into a planar lipid bilayer. When junctional SR vesicles were used for channel incorporation (native RyR1), DIDS increased the mean P(o) (open probability) of RyR1 without affecting unitary conductance when Cs+ was used as the charge carrier. Lifetime analysis of single RyR1 activities showed that 10 microM DIDS induced reversible long-lived open events (P(o)=0.451+/-0.038) in the presence of 10 microM Ca2+, due mainly to a new third component for both open and closed time constants. However, when purified RyR1 was examined in the same condition, 10 microM DIDS became considerably less potent (P(o)=0.206+/-0.025), although the caffeine response was similar between native and purified RyR1. Hence we postulated that a DIDS-binding protein, essential for the DIDS sensitivity of RyR1, was lost during RyR1 purification. DIDS-affinity column chromatography of solubilized junctional SR, and MALDI-TOF (matrix-assisted laser-desorption ionization-time-of-flight) MS analysis of the affinity-column-associated proteins, identified four major DIDS-binding proteins in the SR fraction. Among them, aldolase was the only protein that greatly potentiated DIDS sensitivity. The association between RyR1 and aldolase was further confirmed by co-immunoprecipitation and aldolase-affinity batch-column chromatography. Taken together, we conclude that aldolase is physically associated with RyR1 and could confer a considerable potentiation of the DIDS effect on RyR1. PMID:16817780

  10. Two rules for callosal connectivity in striate cortex of the rat.

    PubMed

    Lewis, J W; Olavarria, J F

    1995-10-01

    In the rat, callosal cells occupy lateral as well as medial portions of striate cortex. In the region of the border between areas 17 and 18, which contains a representation of the vertical meridian of the visual field, cells projecting through the corpus callosum are concentrated throughout the depth of the cortex. In contrast, in medial portion of striate cortex, where peripheral portions of the visual field are represented, callosal cells are preferentially found in infragranular layers. These differences in topography and laminar distribution suggest that these callosal regions, referred to as medial and lateral callosal regions in the present study, subserve different functions. We explored this possibility by analyzing the patterns of callosal linkages in these two callosal regions. We charted the location of retrogradely labeled cells within striate cortex of one hemisphere after placing restricted injections of one or more fluorescent tracers into selected sites in the contralateral striate cortex. We found the medial and lateral callosal regions have distinctly different topographic organizations. Injections into medial striate cortex of one hemisphere produced labeled cells predominantly in mirror-symmetric loci in medial portions of contralateral striate cortex. The arrangement of these connections suggests that they mediate direct interactions between cortical regions representing visual fields located symmetrically on opposite sides of the vertical meridian of the visual field. In contrast, the mapping in the lateral callosal region is reversed: injections into the 17/18a border produced labeled fields located medial to the contralateral 17/18a border, while injections slightly medial to the 17/18a border produced labeled fields located at the contralateral 17/18a border.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8550874

  11. Detyrosinated microtubules modulate mechanotransduction in heart and skeletal muscle

    PubMed Central

    Kerr, Jaclyn P.; Robison, Patrick; Shi, Guoli; Bogush, Alexey I.; Kempema, Aaron M.; Hexum, Joseph K.; Becerra, Natalia; Harki, Daniel A.; Martin, Stuart S.; Raiteri, Roberto; Prosser, Benjamin L.; Ward, Christopher W.

    2015-01-01

    In striated muscle, X-ROS is the mechanotransduction pathway by which mechanical stress transduced by the microtubule network elicits reactive oxygen species. X-ROS tunes Ca2+ signalling in healthy muscle, but in diseases such as Duchenne muscular dystrophy (DMD), microtubule alterations drive elevated X-ROS, disrupting Ca2+ homeostasis and impairing function. Here we show that detyrosination, a post-translational modification of α-tubulin, influences X-ROS signalling, contraction speed and cytoskeletal mechanics. In the mdx mouse model of DMD, the pharmacological reduction of detyrosination in vitro ablates aberrant X-ROS and Ca2+ signalling, and in vivo it protects against hallmarks of DMD, including workload-induced arrhythmias and contraction-induced injury in skeletal muscle. We conclude that detyrosinated microtubules increase cytoskeletal stiffness and mechanotransduction in striated muscle and that targeting this post-translational modification may have broad therapeutic potential in muscular dystrophies. PMID:26446751

  12. Protein kinase C and preconditioning: role of the sarcoplasmic reticulum.

    PubMed

    Yamamura, Ken; Steenbergen, Charles; Murphy, Elizabeth

    2005-12-01

    Activation of protein kinase C (PKC) is cardioprotective, but the mechanism(s) by which PKC mediates protection is not fully understood. Inasmuch as PKC has been well documented to modulate sarcoplasmic reticulum (SR) Ca2+ and because altered SR Ca2+ handling during ischemia is involved in cardioprotection, we examined the role of PKC-mediated alterations of SR Ca2+ in cardioprotection. Using isolated adult rat ventricular myocytes, we found that addition of 1,2-dioctanoyl-sn-glycerol (DOG), to activate PKC under conditions that reduced myocyte death associated with simulated ischemia and reperfusion, also reduced SR Ca2+. Cell death was 57.9 +/- 2.9% and 47.3 +/- 1.8% in untreated and DOG-treated myocytes, respectively (P < 0.05). Using fura 2 fluorescence to monitor Ca2+ transients and caffeine-releasable SR Ca2+, we examined the effect of DOG on SR Ca2+. Caffeine-releasable SR Ca2+ was significantly reduced (by approximately 65%) after 10 min of DOG treatment compared with untreated myocytes (P < 0.05). From our examination of the mechanism by which PKC alters SR Ca2+, we present the novel finding that DOG treatment reduced the phosphorylation of phospholamban (PLB) at Ser16. This effect is mediated by PKC-epsilon, because a PKC-epsilon-selective inhibitory peptide blocked the DOG-mediated decrease in phosphorylation of PLB and abolished the DOG-induced reduction in caffeine-releasable SR Ca2+. Using immunoprecipitation, we further demonstrated that DOG increased the association between protein phosphatase 1 and PLB. These data suggest that activated PKC-epsilon reduces SR Ca2+ content through PLB dephosphorylation and that reduced SR Ca2+ may be important in cardioprotection. PMID:16055516

  13. Muscle as a “Mediator“ of Systemic Metabolism

    PubMed Central

    Baskin, Kedryn K.; Winders, Benjamin R.; Olson, Eric N.

    2015-01-01

    Skeletal and cardiac muscles play key roles in the regulation of systemic energy homeostasis and display remarkable plasticity in their metabolic responses to caloric availability and physical activity. In this Perspective we discuss recent studies highlighting transcriptional mechanisms that govern systemic metabolism by striated muscles. We focus on the participation of the Mediator complex in this process, and suggest that tissue-specific regulation of Mediator subunits impacts metabolic homeostasis. PMID:25651178

  14. A region of the myosin rod important for interaction with paramyosin in Caenorhabditis elegans striated muscle.

    PubMed Central

    Hoppe, P E; Waterston, R H

    2000-01-01

    The precise arrangement of molecules within the thick filament, as well as the mechanisms by which this arrangement is specified, remains unclear. In this article, we have exploited a unique genetic interaction between one isoform of myosin heavy chain (MHC) and paramyosin in Caenorhabditis elegans to probe the molecular interaction between MHC and paramyosin in vivo. Using chimeric myosin constructs, we have defined a 322-residue region of the MHC A rod critical for suppression of the structural and motility defects associated with the unc-15(e73) allele. Chimeric constructs lacking this region of MHC A either fail to suppress, or act as dominant enhancers of, the e73 phenotype. Although the 322-residue region is required for suppression activity, our data suggest that sequences along the length of the rod also play a role in the isoform-specific interaction between MHC A and paramyosin. Our genetic and cell biological analyses of construct behavior suggest that the 322-residue region of MHC A is important for thick filament stability. We present a model in which this region mediates an avid interaction between MHC A and paramyosin in parallel arrangement in formation of the filament arms. PMID:11014812

  15. [Mode of formation of the flight muscles in a nematocerous Diptera].

    PubMed

    Lebart-Pedebas, M C; Auber, J

    1982-01-01

    An electron microscope study was conducted on the origin of the dorsal longitudinal muscles of a Nematocerous Diptera (Chironomus). These imaginal muscles arise from three pairs of slender larval muscles that are characterized by the presence of myoblasts located beneath the basal lamina and adhering to the sarcoplasmic membrane. During the last larval instar the myoblasts increase in number, each of the associated muscle fibers loses its contractile material and splits longitudinally into two to form six columns of sarcoplasm. Differentiation of the fibrillar material begins in each of the six muscle rudiments after the adhering myoblasts have become incorporated. There are several possible origins for these myoblasts: they may be embryonic cells that persist in association with the larval muscle fibers; or --as in the case of Cyclorrhaphous Diptera-- they may migrate from elsewhere to invest these fibers. PMID:7138012

  16. Ultrastructure of geniculocortical synaptic connections in the tree shrew striate cortex.

    PubMed

    Familtsev, Dmitry; Quiggins, Ranida; Masterson, Sean P; Dang, Wenhao; Slusarczyk, Arkadiusz S; Petry, Heywood M; Bickford, Martha E

    2016-04-15

    To determine whether thalamocortical synaptic circuits differ across cortical areas, we examined the ultrastructure of geniculocortical terminals in the tree shrew striate cortex to compare directly the characteristics of these terminals with those of pulvinocortical terminals (examined previously in the temporal cortex of the same species; Chomsung et al. [] Cereb Cortex 20:997-1011). Tree shrews are considered to represent a prototype of early prosimian primates but are unique in that sublaminae of striate cortex layer IV respond preferentially to light onset (IVa) or offset (IVb). We examined geniculocortical inputs to these two sublayers labeled by tracer or virus injections or an antibody against the type 2 vesicular glutamate antibody (vGLUT2). We found that layer IV geniculocortical terminals, as well as their postsynaptic targets, were significantly larger than pulvinocortical terminals and their postsynaptic targets. In addition, we found that 9-10% of geniculocortical terminals in each sublamina contacted GABAergic interneurons, whereas pulvinocortical terminals were not found to contact any interneurons. Moreover, we found that the majority of geniculocortical terminals in both IVa and IVb contained dendritic protrusions, whereas pulvinocortical terminals do not contain these structures. Finally, we found that synaptopodin, a protein uniquely associated with the spine apparatus, and telencephalin (TLCN, or intercellular adhesion molecule type 5), a protein associated with maturation of dendritic spines, are largely excluded from geniculocortical recipient layers of the striate cortex. Together our results suggest major differences in the synaptic organization of thalamocortical pathways in striate and extrastriate areas. PMID:26399201

  17. Striated boulder pavements within glaciomarine diamicts of the Yakataga Formation, Middleton Island, Alaska

    SciTech Connect

    Eyles, C.H.

    1985-01-01

    The presence of striated boulder pavements in glacial sequences is often cited as evidence of transport and deposition by grounded glacier ice. However, recent reports show that striated pavements also form in non-glacial environments by the abrasion of boulder lag surfaces by floating glacier and seasonal ice. Several striated boulder pavements are identified within Early Pleistocene upper Yakataga Formation sediments exposed on Middleton Island close to the southern edge of the Gulf of Alaska continental shelf. The sequence is dominated by thick stratiform units of massive and stratified diamict formed by the settling of fine-grained sands and muds from suspension together with ice-rafted debris. Boulder pavements outcrop as extensive planar horizons within the diamicts, can be traced for several kilometers along strike and consist of single lines of clasts with faceted upper surfaces showing consistently oriented striation directions. Clasts are not preferentially aligned, however, and do not have the characteristic bullet shape of boulders transported at a glacier base and deposited by lodgement processes. Striated boulder pavements on Middleton Island appear to have formed as boulder lag surfaces generated by wave and tidal current reworking of diamict on relatively shallow banks. Lags were then overridden and abraded by a grounding ice shelf. The glacially-abraded boulder pavements on Middleton Island record the repeated expansion of a continuous ice shelf to the edge of the Gulf of Alaska continental shelf during the Early Pleistocene.

  18. Short-term effects of β2-AR blocker ICI 118,551 on sarcoplasmic reticulum SERCA2a and cardiac function of rats with heart failure

    PubMed Central

    Gong, Haibin; Li, Yanfei; Wang, Lei; Lv, Qian; Wang, Xiuli

    2016-01-01

    The study was conducted to examine the effects of ICI 118,551 on the systolic function of cardiac muscle cells of rats in heart failure and determine the molecular mechanism of selective β2-adrenergic receptor (β2-AR) antagonist on these cells. The chronic heart failure model for rats was prepared through abdominal aortic constriction and separate cardiac muscle cells using the collagenase digestion method. The rats were then divided into Sham, HF and HF+ICI 50 nM goups and cultivated for 48 h. β2-AR, Gi/Gs and sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) protein expression levels in the cardiac muscle cells were evaluated by western blotting and changes in the systolic function of cardiac muscle cells based on the boundary detection system of contraction dynamics for individual cells was measured. The results showed that compared with the Sham group, the survival rate, percentage of basic contraction and maximum contraction amplitude percentage of cardiac muscle cells with heart failure decreased, Gi protein expression increased while Gs and SERCA2a protein expression decreased. Compared with the HF group, the maximum contraction amplitude percentage of cardiac muscle cells in group HF+ICI 50 nM decreased, the Gi protein expression level increased while the SERCA2a protein expression level decreased. Following the stimulation of Ca2+ and ISO, the maximum contraction amplitude percentage of cardiac muscle cells in the HF+ICI 50 nM group was lower than that in group HF. This indicated that ICI 118,551 has negative inotropic effects on cardiac muscle cells with heart failure, which may be related to Gi protein. Systolic function of cardiac muscle cells with heart failure can therefore be reduced by increasing Gi protein expression and lowering SERCA2a protein expression. PMID:27602067

  19. Muscle-Specific Splicing of a Heterologous Exon Mediated by a Single Muscle-Specific Splicing Enhancer from the Cardiac Troponin T Gene

    PubMed Central

    Cooper, Thomas A.

    1998-01-01

    The chicken cardiac troponin T (cTNT) gene contains a single 30-nucleotide alternative exon that is included in embryonic striated muscle and skipped in the adult. Transient-transfection analysis of cTNT minigenes in muscle and fibroblast cell cultures previously identified four muscle-specific splicing enhancers (MSEs) that promote exon inclusion specifically in embryonic striated muscle cultures. Three MSEs located in the intron downstream from the alternative exon were sufficient for muscle-specific exon inclusion. In the present study, the boundaries of these MSEs were defined by scanning mutagenesis, allowing analysis of individual elements in gain-of-function experiments. Concatamers of MSE2 were necessary and sufficient to promote muscle-specific inclusion of a heterologous exon, indicating that it is a target for muscle-specific regulation. Sequences present in MSE2 are also found in MSE4, suggesting that these two MSEs act in a similar manner. MSE3 appears to be different from MSE2 and MSE4 yet is able to functionally replace both of these elements, demonstrating functional redundancy of elements that are likely to bind different factors. MSE2 and MSE4 each contain a novel sequence motif that is found adjacent to a number of alternative exons that undergo regulated splicing in striated muscle, suggesting a common role for this element in muscle-specific regulation. PMID:9671461

  20. Mechanism of fluorescence and conformational changes of the sarcoplasmic calcium binding protein of the sand worm Nereis diversicolor upon Ca2+ or Mg2+ binding.

    PubMed

    Sillen, Alain; Verheyden, Stefan; Delfosse, Lotte; Braem, Tania; Robben, Johan; Volckaert, Guido; Engelborghs, Yves

    2003-09-01

    The calcium-binding protein isolated from the sarcoplasm of the muscles of the sand worm Nereis diversicolor has four EF-hands and three active binding sites for Ca(2+) or Mg(2+). Nereis diversicolor sarcoplasmic calcium-binding protein contains three tryptophan residues at positions 4, 57, and 170, respectively. The Wt protein shows a very limited fluorescence increase upon binding of Ca(2+) or Mg(2+). Single-tryptophan-containing mutants were produced and purified. The fluorescence titrations of these mutants show a limited decrease of the affinity for calcium, but no alterations of the cooperativity. Upon adding calcium, Trp170 shows a strong fluorescence increase, Trp57 an extensive fluorescence decrease, and Trp4 shows no fluorescence change. Therefore mutant W4F/W170F is ideally suited to analyze the fluorescence titrations and to study the binding mechanism. Mutations of the calcium ligands at the z-position in the three binding sites show no effect at site I and a total loss of cooperativity at sites III and IV. The quenching of Trp57 upon calcium binding is dependent on the presence of arginine R25, but this residue is not just a simple dynamic quencher. The role of the salt bridge R25-D58 is also investigated. PMID:12944301

  1. Differential mechanism of the effects of ester-type local anesthetics on sarcoplasmic reticulum Ca-ATPase.

    PubMed

    Sánchez, G A; Di Croce, D E; de la Cal, C; Richard, S B; Takara, D

    2013-12-01

    The effect of the local anesthetics procaine and tetracaine on sarcoplasmic reticulum membranes isolated from two masticatory muscles, masseter and medial pterygoid, was tested and compared to fast-twitch muscles. The effects of the anesthetics on Ca-ATPase activity, calcium binding, uptake, and phosphorylation of the enzyme by inorganic phosphate (Pi) were tested with radioisotopic methods. Calcium binding to the Ca-ATPase was non-competitively inhibited, and the enzymatic activity decreased in a concentration-dependent manner. The inhibition of the activity depended on pH, calcium concentration, the presence of the calcium ionophore calcimycin, and the membrane protein concentration. Unlike fast-twitch membranes, the pre-exposure of the masseter and medial pterygoid membranes to the anesthetics enhanced the enzymatic activity in the absence of calcimycin, supporting their permeabilizing effect. Procaine and tetracaine also interfered with the calcium transport capability, decreasing the maximal uptake without modification of the calcium affinity for the ATPase. Besides, the anesthetics inhibited the phosphorylation of the enzyme by Pi in a competitive manner. Tetracaine revealed a higher inhibitory potency on Ca-ATPase compared to procaine, and the inhibitory concentrations were lower than usual clinical doses. It is concluded that procaine and tetracaine not only affect key steps of the Ca-ATPase enzymatic cycle but also exert an indirect effect on membrane permeability to calcium and suggest that the consequent myoplasmic calcium increase induced by the anesthetics might account for myotoxic effects, such as sustained contraction and eventual rigidity of both fast-twitch and masticatory muscles. PMID:23949087

  2. E-box sites and a proximal regulatory region of the muscle creatine kinase gene differentially regulate expression in diverse skeletal muscles and cardiac muscle of transgenic mice.

    PubMed Central

    Shield, M A; Haugen, H S; Clegg, C H; Hauschka, S D

    1996-01-01

    Previous analysis of the muscle creatine kinase (MCK) gene indicated that control elements required for transcription in adult mouse muscle differed from those required in cell culture, suggesting that distinct modes of muscle gene regulation occur in vivo. To examine this further, we measured the activity of MCK transgenes containing E-box and promoter deletions in a variety of striated muscles. Simultaneous mutation of three E boxes in the 1,256-bp MCK 5' region, which abolished transcription in muscle cultures, had strikingly different effects in mice. The mutations abolished transgene expression in cardiac and tongue muscle and caused a reduction in expression in the soleus muscle (a muscle with many slow fibers) but did not affect expression in predominantly fast muscles: quadriceps, abdominals, and extensor digitorum longus. Other regulatory sequences with muscle-type-specific activities were found within the 358-bp 5'-flanking region. This proximal region conferred relatively strong expression in limb and abdominal skeletal muscles but was inactive in cardiac and tongue muscles. However, when the 206-bp 5' enhancer was ligated to the 358-bp region, high levels of tissue-specific expression were restored in all muscle types. These results indicate that E boxes and a proximal regulatory region are differentially required for maximal MCK transgene expression in different striated muscles. The overall results also imply that within skeletal muscles, the steady-state expression of the MCK gene and possibly other muscle genes depends on transcriptional mechanisms that differ between fast and slow fibers as well as between the anatomical and physiological attributes of each specific muscle. PMID:8756664

  3. Cytoplasmic nanojunctions between lysosomes and sarcoplasmic reticulum are required for specific calcium signaling.

    PubMed

    Fameli, Nicola; Ogunbayo, Oluseye A; van Breemen, Cornelis; Evans, A Mark

    2014-01-01

    Herein we demonstrate how nanojunctions between lysosomes and sarcoplasmic reticulum (L-SR junctions) serve to couple lysosomal activation to regenerative, ryanodine receptor-mediated cellular Ca (2+) waves. In pulmonary artery smooth muscle cells (PASMCs) it has been proposed that nicotinic acid adenine dinucleotide phosphate (NAADP) triggers increases in cytoplasmic Ca (2+) via L-SR junctions, in a manner that requires initial Ca (2+) release from lysosomes and subsequent Ca (2+)-induced Ca (2+) release (CICR) via ryanodine receptor (RyR) subtype 3 on the SR membrane proximal to lysosomes. L-SR junction membrane separation has been estimated to be < 400 nm and thus beyond the resolution of light microscopy, which has restricted detailed investigations of the junctional coupling process. The present study utilizes standard and tomographic transmission electron microscopy to provide a thorough ultrastructural characterization of the L-SR junctions in PASMCs. We show that L-SR nanojunctions are prominent features within these cells and estimate that the junctional membrane separation and extension are about 15 nm and 300 nm, respectively. Furthermore, we develop a quantitative model of the L-SR junction using these measurements, prior kinetic and specific Ca (2+) signal information as input data. Simulations of NAADP-dependent junctional Ca (2+) transients demonstrate that the magnitude of these signals can breach the threshold for CICR via RyR3. By correlation analysis of live cell Ca (2+) signals and simulated Ca (2+) transients within L-SR junctions, we estimate that "trigger zones" comprising 60-100 junctions are required to confer a signal of similar magnitude. This is compatible with the 110 lysosomes/cell estimated from our ultrastructural observations. Most importantly, our model shows that increasing the L-SR junctional width above 50 nm lowers the magnitude of junctional [Ca (2+)] such that there is a failure to breach the threshold for CICR via RyR3. L

  4. Effects of postmortem aging and hydrodynamic pressure processing on sarcoplasmic proteins and beef tenderness

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to determine the effects of hydrodynamic pressure processing (HDP) and postmortem aging on the sarcoplasmic protein fraction of beef strip loins. Loins (n=12) were halved at 48 h postmortem and assigned to HDP or control treatments. Following treatment, each half was ...

  5. Sarcoplasmic Reticulum Calcium Release Channels in Ventricles of Older Adult Hamsters

    ERIC Educational Resources Information Center

    Nicholl, Peter A.; Howlett, Susan E.

    2006-01-01

    Whether the density of sarcoplasmic reticulum (SR) calcium release channels/ryanodine receptors in the heart declines with age is not clear. We investigated age-related changes in the density of [3H]-ryanodine receptors in crude ventricular homogenates, which contained all ligand binding sites in heart and in isolated junctional SR membranes.…

  6. Effect of hydrodynamic pressure processing and aging on sarcoplasmic proteins of beef strip loins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated the effects of hydrodynamic pressure processing (HDP) and aging on the sarcoplasmic proteins of beef strip loins. Loins (n=12) were halved at 48 h postmortem and assigned to HDP or control treatments. Following treatment, each half was divided into three portions for aging (0, 5...

  7. Modulation of sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase activity and oxidative modification during the development of adjuvant arthritis.

    PubMed

    Strosova, Miriam K; Karlovska, Janka; Zizkova, Petronela; Kwolek-Mirek, Magdalena; Ponist, Silvester; Spickett, Corinne M; Horakova, Lubica

    2011-07-01

    Adjuvant arthritis (AA) was induced by intradermal administration of Mycobacterium butyricum to the tail of Lewis rats. In sarcoplasmic reticulum (SR) of skeletal muscles, we investigated the development of AA. SR Ca(2+)-ATPase (SERCA) activity decreased on day 21, suggesting possible conformational changes in the transmembrane part of the enzyme, especially at the site of the calcium binding transmembrane part. These events were associated with an increased level of protein carbonyls, a decrease in cysteine SH groups, and alterations in SR membrane fluidity. There was no alteration in the nucleotide binding site at any time point of AA, as detected by a FITC fluorescence marker. Some changes observed on day 21 appeared to be reversible, as indicated by SERCA activity, cysteine SH groups, SR membrane fluidity, protein carbonyl content and fluorescence of an NCD-4 marker specific for the calcium binding site. The reversibility may represent adaptive mechanisms of AA, induced by higher relative expression of SERCA, oxidation of cysteine, nitration of tyrosine and presence of acidic phospholipids such as phosphatidic acid. Nitric oxide may regulate cytoplasmic Ca(2+) level through conformational alterations of SERCA, and decreasing levels of calsequestrin in SR may also play regulatory role in SERCA activity and expression. PMID:21531199

  8. Protective effect of antioxidants against sarcoplasmic reticulum (SR) oxidation by Fenton reaction, however without prevention of Ca-pump activity.

    PubMed

    Voss, Peter; Engels, Martina; Strosova, Miriam; Grune, Tilman; Horakova, Lubica

    2008-10-01

    The Ca(2+)-ATPase of the sarcoplasmic reticulum (SERCA) of rabbit skeletal muscle was oxidized by Fe2+/H2O2/ascorbic acid (AA), a system which generates HO(.) radicals according to the Fenton reaction: (Fe2(+)+H2O2-->HO(.)+OH(-)+Fe(3+)) under conditions similar to the pathological state of inflammation. Under these conditions, when hydroxyl-radicals and/or ferryl-radicals are generated, a 50% decrease of the SERCA activity was observed, a significant decrease of SH groups and an increase of protein carbonyl groups and lipid peroxidation were identified. Two new bands, time dependent in density, appeared in the SERCA protein electrophoresis after incubation with the Fenton system (at approximately 50 and 75kDa), probably due to structural changes as supported also by trypsin digestion. Immunoblotting of DNPH derivatized protein bound carbonyls detected a time dependent increase after incubation of SERCA with the Fenton system. Trolox and the pyridoindole stobadine (50microM) protected SR against oxidation induced via the Fenton system by preventing SH group oxidation and lipid peroxidation. Pycnogenol((R)) and EGb761 (40microg/ml) protected SERCA in addition against protein bound carbonyl formation. In spite of the antioxidant effects, trolox and stobadine were not able to prevent a decrease in the SERCA Ca(2+)-ATPase activity. Pycnogenol and EGb761 even enhanced the decrease of the Ca(2+)-ATPase activity induced by the Fenton system, probably by secondary oxidative reactions. PMID:18692562

  9. Effects of calmodulin and calmodulin inhibitors on Ca uptake by sarcoplasmic reticulum of saponin skinned caudal artery

    SciTech Connect

    Stout, M.A.; Silver, P.J.

    1986-03-05

    Calmodulin (CaM) stimulates plasma membrane transport in many cell types, however, its role in Ca regulation by the sarcoplasmic reticulum (SR) in smooth muscle has not been established. /sup 45/Ca uptake was studied in saponin skinned strips of rat caudal artery as a function of CaM and the CaM inhibitors, W-7, calmidazolium (CaMZ), and trifluoperazine (TFP). Although caudal artery strips lose approximately 30% of total tissue CaM during skinning, 0.3 - 2 ..mu..M CaM did not increase /sup 45/Ca uptake over a wide range of free Ca concentrations (10/sup -8/ - 10/sup -6/M). Neither W-7 nor CaMZ at concentration of 10/sup -4/ - 2 x 10/sup -4/M inhibited the MgATP-dependent Ca uptake. Ca uptake was not affected by 50 ..mu..M TFP but a significant inhibition was produced by 500 ..mu..M. Studies of the effects of TFP on /sup 45/Ca efflux indicated that TFP concentrations which inhibited Ca uptake also significantly increased the rate of Ca release. The results suggest that total Ca uptake in caudal artery depends mainly upon MgATP and is not modulated by exogenous CaM or affected by these CaM inhibitors. They cannot preclude that CaM may affect initial velocities or that the CaM inhibitors failed to reach active sites.

  10. Two-dimensional separation of the membrane protein sarcoplasmic reticulum Ca-ATPase for high-performance liquid chromatography-tandem mass spectrometry analysis of posttranslational protein modifications.

    PubMed

    Sharov, Victor S; Galeva, Nadezhda A; Knyushko, Tatyana V; Bigelow, Diana J; Williams, Todd D; Schöneich, Christian

    2002-09-15

    For the characterization of posttranslational modifications of the sarcoplasmic/endoplasmic reticulum Ca-ATPase (SERCA), we developed a two-dimensional separation protocol based on reversed-phase HPLC followed by SDS-PAGE and LC-MS/MS analysis of in-gel tryptic digests. Representative experiments are shown for the rabbit fast-twitch skeletal muscle isoform SERCA1. Matrix-assisted laser desorption-ionization and electrospray ionization-mass spectrometry analyses of SERCA1 tryptic digests revealed ca. 66% coverage of the protein sequence. This approach was used for the detection and quantitation of nitrotyrosine formation after exposure of SERCA1 to peroxynitrite in vitro. At molar ratios of nitrotyrosine to protein of 0.23 we confirmed by LC-MS/MS the nitration of predominantly Tyr(122) in the SERCA1 sequence. PMID:12419347

  11. Food control by applied biochemistry of marine organisms: Comparison of proteins and metabolites from fish and invertebrate muscle

    NASA Astrophysics Data System (ADS)

    Rehbein, H.

    1995-03-01

    Most fishery products consist of muscle tissue from fish and invertebrates. Differences in the molecular structure and in metabolism of muscles can be utilized to characterize and identify various seafood. Creatine and arginine were found to be useful for the differentiation between imitation crab/shrimp meat and real crustacean meat. Octopine served as an indicator for the meat of cephalopods and mussels. In order to identify the animal species of a fishery product, several electrophoretic methods were used. It depended on the type of product, whether sarcoplasmic or myofibrillar proteins were better suited. Raw products were best analysed by isoelectric focusing of sarcoplasmic proteins. Two types of sarcoplasmic calcium-binding proteins, parvalbumins of fish and soluble calcium-binding proteins of invertebrates, were especially useful for species identification. Due to their thermal stability, these proteins gave species-specific patterns for cooked products, too. Two other techniques were also investigated: urea gel isoelectric focusing, and sodium dodecyl sulphate — polyacrylamide gel electrophoresis. These methods were applied in the analysis of products where the sarcoplasmic proteins had been removed by washing steps, i.e. imitation crab meat made from surimi, and of other raw and cooked products. The myosin light chains gave protein patterns that were characteristic for many species. Paramyosin, which is absent from vertebrate muscle, indicated the presence of mollusc muscle. It was shown that the determination, of arginine kinase activity enabled differentiation between raw fish muscle and invertebrate muscles.

  12. Non-conscious recognition of affect in the absence of striate cortex.

    PubMed

    de Gelder, B; Vroomen, J; Pourtois, G; Weiskrantz, L

    1999-12-16

    Functional neuroimaging experiments have shown that recognition of emotional expressions does not depend on awareness of visual stimuli and that unseen fear stimuli can activate the amygdala via a colliculopulvinar pathway. Perception of emotional expressions in the absence of awareness in normal subjects has some similarities with the unconscious recognition of visual stimuli which is well documented in patients with striate cortex lesions (blindsight). Presumably in these patients residual vision engages alternative extra-striate routes such as the superior colliculus and pulvinar. Against this background, we conjectured that a blindsight subject (GY) might recognize facial expressions presented in his blind field. The present study now provides direct evidence for this claim. PMID:10716205

  13. Role of retinal input on the development of striate-extrastriate patterns of connections in the rat.

    PubMed

    Laing, R J; Bock, A S; Lasiene, J; Olavarria, J F

    2012-10-01

    Previous studies have shown that retinal input plays an important role in the development of interhemispheric callosal connections, but little is known about the role retinal input plays on the development of ipsilateral striate-extrastriate connections and the interplay that might exist between developing ipsilateral and callosal pathways. We analyzed the effects of bilateral enucleation performed at different ages on both the distribution of extrastriate projections originating from restricted loci in medial, acallosal striate cortex, and the overall pattern of callosal connections revealed following multiple tracer injections. As in normal rats, striate-extrastriate projections in rats enucleated at birth consisted of multiple, well-defined fields that were largely confined to acallosal regions throughout extrastriate cortex. However, these projections were highly irregular and variable, and they tended to occupy correspondingly anomalous and variable acallosal regions. Moreover, area 17, but not area 18a, was smaller in enucleates compared to controls, resulting in an increase in the divergence of striate projections. Anomalies in patterns of striate-extrastriate projections were not observed in rats enucleated at postnatal day (P)6, although the size of area 17 was still reduced in these rats. These results indicate that the critical period during which the eyes influence the development of striate-extrastriate, but not the size of striate cortex, ends by P6. Finally, enucleation did not change the time course and definition of the initial invasion of axons into gray matter, suggesting that highly variable striate projections patterns do not result from anomalous pruning of exuberant distributions of 17-18a fibers in gray matter. PMID:22430936

  14. Defining muscle elastance as a parameter.

    PubMed

    Palladino, Joseph L; Noordergraaf, Abraham

    2007-01-01

    Functional descriptions of striated muscle are often based on the measured variables force and initial velocity of shortening, embodied as Hill's contractile element. The fundamental difficulty of describing the mechanical properties of muscle with a force-velocity relation that is set a priori, and the practical problem of the act of measurement changing muscle's force-velocity relation or elastance curve, are described. As an alternative, a new model of muscle contraction is presented, which characterizes muscle's contractile state with parameters, rather than variables. Muscle is treated as a force generator that is time, length, and velocity dependent. Muscle dynamics develop from a single equation based on the formation and relaxation of crossbridge bonds. This analytical function permits the calculation of muscle elastance via E(m)=[abstract: see text]. This new muscle model is defined independently from load properties, and muscle elastance is dynamic and reflects changing numbers of crossbridge bonds. This parameter is more representative of the mechanical properties of muscle than are variables such as muscle force and shortening velocity. PMID:18003207

  15. DisAp-dependent striated fiber elongation is required to organize ciliary arrays

    PubMed Central

    Galati, Domenico F.; Bonney, Stephanie; Kronenberg, Zev; Clarissa, Christina; Yandell, Mark; Elde, Nels C.; Jerka-Dziadosz, Maria; Giddings, Thomas H.; Frankel, Joseph

    2014-01-01

    Cilia-organizing basal bodies (BBs) are microtubule scaffolds that are visibly asymmetrical because they have attached auxiliary structures, such as striated fibers. In multiciliated cells, BB orientation aligns to ensure coherent ciliary beating, but the mechanisms that maintain BB orientation are unclear. For the first time in Tetrahymena thermophila, we use comparative whole-genome sequencing to identify the mutation in the BB disorientation mutant disA-1. disA-1 abolishes the localization of the novel protein DisAp to T. thermophila striated fibers (kinetodesmal fibers; KFs), which is consistent with DisAp’s similarity to the striated fiber protein SF-assemblin. We demonstrate that DisAp is required for KFs to elongate and to resist BB disorientation in response to ciliary forces. Newly formed BBs move along KFs as they approach their cortical attachment sites. However, because they contain short KFs that are rotated, BBs in disA-1 cells display aberrant spacing and disorientation. Therefore, DisAp is a novel KF component that is essential for force-dependent KF elongation and BB orientation in multiciliary arrays. PMID:25533842

  16. Molecular organization in striated domains induced by transmembrane alpha-helical peptides in dipalmitoyl phosphatidylcholine bilayers.

    PubMed

    Sparr, Emma; Ganchev, Dragomir N; Snel, Margot M E; Ridder, Anja N J A; Kroon-Batenburg, Loes M J; Chupin, Vladimir; Rijkers, Dirk T S; Killian, J Antoinette; de Kruijff, Ben

    2005-01-11

    Transmembrane (TM) alpha-helical peptides with neutral flanking residues such as tryptophan form highly ordered striated domains when incorporated in gel-state 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers and inspected by atomic force microscopy (AFM) (1). In this study, we analyze the molecular organization of these striated domains using AFM, photo-cross-linking, fluorescence spectroscopy, nuclear magnetic resonance (NMR), and X-ray diffraction techniques on different functionalized TM peptides. The results demonstrate that the striated domains consist of linear arrays of single TM peptides with a dominantly antiparallel organization in which the peptides interact with each other and with lipids. The peptide arrays are regularly spaced by +/-8.5 nm and are separated by somewhat perturbed gel-state lipids with hexagonally organized acyl chains, which have lost their tilt. This system provides an example of how domains of peptides and lipids can be formed in membranes as a result of a combination of specific peptide-peptide and peptide-lipid interactions. PMID:15628840

  17. Biochemical heterogeneity of skeletal-muscle microsomal membranes. Membrane origin, membrane specificity and fibre types

    PubMed Central

    Salviati, Giovanni; Volpe, Pompeo; Salvatori, Sergio; Betto, Romeo; Damiani, Ernesto; Margreth, Alfredo; Pasquali-Ronchetti, Ivonne

    1982-01-01

    1. Microsomes were isolated from rabbit fast-twitch and slow-twitch muscle and were separated into heavy and light fractions by centrifugation in a linear (0.3–2m) sucrose density gradient. The membrane origin of microsomal vesicles was investigated by studying biochemical markers of the sarcoplasmic-reticulum membranes and of surface and T-tubular membranes, as well as their freeze-fracture properties. 2. Polyacrylamide-gel electrophoresis showed differences in the Ca2+-dependent ATPase/calsequestrin ratio between heavy and light fractions, which were apparently consistent with their respective origin from cisternal and longitudinal sarcoplasmic reticulum, as well as unrelated differences, such as peptides specific to slow-muscle microsomes (mol.wts. 76000, 60000, 56000 and 45000). 3. Freeze-fracture electron microscopy of muscle microsomes demonstrated that vesicles truly derived from the sarcoplasmic reticulum, with an average density of 9nm particles on the concave face of about 3000/μm2 for both fast and slow muscle, were admixed with vesicles with particle densities below 1000/μm2. 4. As determined in the light fractions, the sarcoplasmic-reticulum vesicles accounted for 84% and 57% of the total number of microsomal vesicles, for fast and slow muscle respectively. These values agreed closely with the percentage values of Ca2+-dependent ATPase protein obtained by gel densitometry. 5. The T-tubular origin of vesicles with a smooth concave fracture face in slow-muscle microsomes is supported by their relative high content in total phospholipid and cholesterol, compared with the microsomes of fast muscle, and by other correlative data, such as the presence of (Na++K+)-dependent ATPase activity and of low amounts of Na+-dependent membrane phosphorylation. 6. Among intrinsic sarcoplasmic-reticulum membrane proteins, a proteolipid of mol.wt. 12000 is shown to be identical in the microsomes of both fast and slow muscle and the Ca2+-dependent ATPase to be

  18. Muscle-specificity of age-related changes in markers of autophagy and sphingolipid metabolism.

    PubMed

    Russ, David W; Boyd, Iva M; McCoy, Katherine M; McCorkle, Katherine W

    2015-12-01

    Our previous findings indicate that the gastrocnemius muscle of aging rats exhibits impairments of muscle quality (force/unit muscle tissue) and autophagy and increased sarcoplasmic reticulum stress. The purpose of this study was to examine age-related changes in soleus muscle contractility and in markers of autophagy in the soleus and gastrocnemius muscles. We assessed in situ muscle force and size in the soleus muscle of adult (7-8 months) and aged (24-26 months) male, F344/BN rats. We used immunoblotting to compare abundance of markers of autophagy, sarcoplasmic reticulum (SR) stress and sphingolipid metabolism in the soleus and medial gastrocnemius (MG) muscles of these animals. Relative to adults, aged rats maintained soleus muscle quality and increased muscle size, resulting in increased tetanic force production. Immunoblotting revealed a general pattern of an age-related reduction of basal autophagy, despite increases in indicators of SR stress and upstream autophagic pathway activation in the MG. The MG also exhibited changes in markers of sphingolipid metabolism suggestive of increased muscle ceramide. Minimal age-related changes were observed in the soleus. The soleus maintains muscle mass and quality with age, and exhibits fewer age-related changes in markers of stress and autophagy than the MG. Based on these data, we suggest that maintenance of autophagy may preserve muscle quality by preventing excessive SR stress. PMID:26296420

  19. Methods for Creating and Animating a Computer Model Depicting the Structure and Function of the Sarcoplasmic Reticulum Calcium ATPase Enzyme.

    ERIC Educational Resources Information Center

    Chen, Alice Y.; McKee, Nancy

    1999-01-01

    Describes the developmental process used to visualize the calcium ATPase enzyme of the sarcoplasmic reticulum which involves evaluating scientific information, consulting scientists, model making, storyboarding, and creating and editing in a computer medium. (Author/CCM)

  20. Impact of aging on mitochondrial function in cardiac and skeletal muscle.

    PubMed

    Hepple, R T

    2016-09-01

    Both skeletal muscle and cardiac muscle are subject to marked structural and functional impairment with aging and these changes contribute to the reduced capacity for exercise as we age. Since mitochondria are involved in multiple aspects of cellular homeostasis including energetics, reactive oxygen species signaling, and regulation of intrinsic apoptotic pathways, defects in this organelle are frequently implicated in the deterioration of skeletal and cardiac muscle with aging. On this basis, the purpose of this review is to evaluate the evidence that aging causes dysfunction in mitochondria in striated muscle with a view towards drawing conclusions about the potential of these changes to contribute to the deterioration seen in striated muscle with aging. As will be shown, impairment in respiration and reactive oxygen species emission with aging are highly variable between studies and seem to be largely a consequence of physical inactivity. On the other hand, both skeletal and cardiac muscle mitochondria are more susceptible to permeability transition and this seems a likely cause of the increased recruitment of mitochondrial-mediated pathways of apoptosis seen in striated muscle. The review concludes by examining the role of degeneration of mitochondrial DNA versus impaired mitochondrial quality control mechanisms in the accumulation of mitochondria that are sensitized to permeability transition, whereby the latter mechanism is favored as the most likely cause. PMID:27033952

  1. YAP-Mediated Mechanotransduction in Skeletal Muscle

    PubMed Central

    Fischer, Martina; Rikeit, Paul; Knaus, Petra; Coirault, Catherine

    2016-01-01

    Skeletal muscle is not only translating chemical energy into mechanical work, it is also a highly adaptive and regenerative tissue whose architecture and functionality is determined by its mechanical and physical environment. Processing intra- and extracellular mechanical signaling cues contributes to the regulation of cell growth, survival, migration and differentiation. Yes-associated Protein (YAP), a transcriptional coactivator downstream of the Hippo pathway and its paralog, the transcriptional co-activator with PDZ-binding motif (TAZ), were recently found to play a key role in mechanotransduction in various tissues including skeletal muscle. Furthermore, YAP/TAZ modulate myogenesis and muscle regeneration and abnormal YAP activity has been reported in muscular dystrophy and rhabdomyosarcoma. Here, we summarize the current knowledge of mechanosensing and -signaling in striated muscle. We highlight the role of YAP signaling and discuss the different routes and hypotheses of its regulation in the context of mechanotransduction. PMID:26909043

  2. Your Muscles

    MedlinePlus

    ... Homework? Here's Help White House Lunch Recipes Your Muscles KidsHealth > For Kids > Your Muscles Print A A ... and skeletal (say: SKEL-uh-tul) muscle. Smooth Muscles Smooth muscles — sometimes also called involuntary muscles — are ...

  3. Form, function and intracortical projections of spiny neurones in the striate visual cortex of the cat.

    PubMed Central

    Martin, K A; Whitteridge, D

    1984-01-01

    We have studied the neuronal circuitry and structure-function relationships of single neurones in the striate visual cortex of the cat using a combination of electrophysiological and anatomical techniques. Glass micropipettes filled with horseradish peroxidase were used to record extracellularly from single neurones. After studying the receptive field properties, the afferent inputs of the neurones were studied by determining their latency of response to electrical stimulation at different positions along the optic pathway. Some cells were thus classified as receiving a mono- or polysynaptic input from afferents of the lateral geniculate nucleus (l.g.n.), via X- or Y-like retinal ganglion cells. Two striking correlations were found between dendritic morphology and receptive field type. All spiny stellate cells, and all star pyramidal cells in layer 4A, had receptive fields with spatially separate on and off subfields (S-type receptive fields). All the identified afferent input to these, the major cell types in layer 4, was monosynaptic from X- or Y-like afferents. Neurones receiving monosynaptic X- or Y-like input were not strictly segregated in layer 4 and the lower portion of layer 3. Nevertheless the X- and Y-like l.g.n. fibres did not converge on any of the single neurones so far studied. Monosynaptic input from the l.g.n. afferents was not restricted to cells lying within layers 4 and 6, the main termination zones of the l.g.n. afferents, but was also received by cells lying in layers 3 and 5. The projection pattern of cells receiving monosynaptic input differed widely, depending on the laminar location of the cell soma. This suggests the presence of a number of divergent paths within the striate cortex. Cells receiving indirect input from the l.g.n. afferents were located mainly within layers 2, 3 and 5. Most pyramidal cells in layer 3 had axons projecting out of the striate cortex, while many axons of the layer 5 pyramids did not. The layer 5 cells showed

  4. Muscle microanatomy and its changes during contraction: the legacy of William Bowman (1816-1892).

    PubMed

    Frixione, Eugenio

    2006-01-01

    Striated muscle fine structure began to be really understood following a comprehensive survey of the matter carried out by William Bowman in the late 1830s. The publications resulting from such a study, the first of which earned for the author a precocious election as Fellow of the Royal Society, are herewith examined in the context of contemporary views on the subject as well as of their subsequent repercussion and current knowledge today. It is shown that not only Bowman succeeded in establishing the true architecture of striated muscle fibres to the extent possible with the most advanced technology available in his day--explaining and eradicating alternative erroneous concepts in the process--but also in correctly describing the basic microstructural changes associated with contraction. In addition, although unrecognized by him or others at the time, his experiments with muscle provided direct evidence for the existence of a selectively permeable cell membrane--in the present meaning of the word--over half a century before its officially accepted discovery. Yet, in spite of these remarkable advances, Bowman arrived at the conclusion that the structure of striated muscle fibres is essentially irrelevant for the mechanism of contraction. Possible reasons behind Bowman's breakthrough accomplishments as a pioneer of modern muscle research, and his failure to understand their significance for muscle physiology, are discussed. PMID:16465470

  5. Single-unit and 2-deoxyglucose studies of side inhibition in macaque striate cortex.

    PubMed Central

    Born, R T; Tootell, R B

    1991-01-01

    In the course of studies to map spatial frequency tuning of neurons in layers 2 and 3 of macaque striate cortex, we found that a high proportion (70%) of cells in the interblob regions responded poorly to full-field gratings, compared with responses to single bars, edges, or delimited gratings. This was most often due to side inhibition, in which increasing the number of cycles of a grating placed within the cell's receptive field causes progressive inhibition of response. Quantitative receptive-field mappings showed, however, that the inhibition can occur within the region activated by a bar, as well as beyond it. The inhibition appears to be orientation-selective, in that a surround grating was more effective at inhibiting the response to a center grating patch if it was of similar orientation. 2-Deoxyglucose experiments confirmed that side inhibition is very widespread in the interblobs of layers 2 and 3 and suggested that it is reduced or lacking in layers 4A through 6. Since layers 2 and 3 of striate cortex are the major source of cortical projections to area V2 and beyond, the prevalence of side stopping in these laminae has implications for theories of cortical visual function. Side-stopped interblob cells may be acting as "contour-pass filters" that filter out redundant information in textured or noisy surfaces, focusing subsequent form processing on contrasts corresponding to object boundaries. Images PMID:1871122

  6. Nitric-oxide-induced vasodilatation: regulation by physiologic s-glutathiolation and pathologic oxidation of the sarcoplasmic endoplasmic reticulum calcium ATPase.

    PubMed

    Cohen, Richard A; Adachi, Takeshi

    2006-05-01

    Nitric-oxide (NO)-induced vasodilatation is impaired in patients with a variety of cardiovascular diseases. Cyclic GMP, the principal mediator of NO-induced smooth muscle relaxation, usually functions normally, and the impairment in endothelial-mediated vasodilatation is attributed to increased oxidants that diminish NO bioactivity. In investigating the mechanisms involved, we found that independently of cyclic GMP, NO stimulates the uptake of cytosolic Ca(2+) via the sarcoplasmic reticulum Ca(2+) ATPase (SERCA), thereby relaxing vascular smooth muscle by lowering intracellular free Ca(2+). Nitric oxide was found to do so by reacting with superoxide to form peroxynitrite, which in turn caused glutathione (GSH) to bind to SERCA cysteine thiols. Most of the GSH was bound to the most reactive thiol on SERCA cysteine-674, and mutation of this residue prevented stimulation of Ca(2+) uptake by NO. In atherosclerotic arteries, we found that NO no longer stimulated SERCA activity because of the irreversible oxidation of the cysteine-674 thiol. These studies not only demonstrate a novel mechanism of NO-induced vasodilatation, but also provide an explanation as to how chronically increased levels of oxidants associated with disease impair vasodilatation in diseased arteries. PMID:16713532

  7. 'Striated Delta' Clouds As Tracers Of Inertia-Gravity Wave Emission From Upper Jets And Extratropical Cyclones

    NASA Astrophysics Data System (ADS)

    Morgan, A. L.; Reeder, M. J.

    2012-12-01

    'Striated Delta' cloud formations are frequently tracers of upper-tropospheric inertia-gravity wave disturbances near the jet stream, coincident with rapid extratropical cyclogenesis (Feren, 1995). The investigation of source mechanisms in this context is important for better understanding of how and where large-amplitude inertia-gravity waves are generated, which propagate energy throughout the atmosphere and transfer it to the mean flow through breaking or attenuation processes. A seasonal study of twenty-eight Striated Delta events in the Australia/New Zealand region during May to September 2009 is analysed in the high-resolution ECMWF YOTC dataset. Mean composite analyses show that Striated Deltas occur in an upper-tropospheric environment of strong horizontal divergence, strong parcel accelerations, strong vertical motion and geostrophic imbalance. Synoptically, the Striated Delta cases occur in the poleward jet exit region near the axis of inflexion between an upstream upper trough and a downstream upper ridge. This is consistent with findings of previous studies regarding the synoptic environment characteristic of gravity wave generation. A Q-vector partitioning analysis suggests that flow curvature and advection of shear are the two greatest components to synoptic scale vertical motion forcing. The Q-Vector analysis also explains the characteristic triangular shape of the Striated Delta cloud formation. It is hypothesised that strong parcel accelerations due to curvature of the flow, as well as air parcel deceleration in the jet streak exit region, are responsible for the generation of inertia-gravity waves evident in the banding of Striated Delta clouds. Furthermore, deep convection is favoured in the poleward jet exit region by the ageostrophic circulation and is also thought to play a role in the generation of waves and the modulation of wavelengths. A distinct and interesting Striated Delta and extratropical cyclogenesis event from September 2009 is

  8. Mechano-regulated Tenascin-C orchestrates muscle repair

    PubMed Central

    Flück, Martin; Mund, Sonja I.; Schittny, Johannes C.; Klossner, Stephan; Durieux, Anne-Cécile; Giraud, Marie-Noëlle

    2008-01-01

    Tenascin-C (TNC) is a mechano-regulated, morphogenic, extracellular matrix protein that is associated with tissue remodeling. The physiological role of TNC remains unclear because transgenic mice engineered for a TNC deficiency, via a defect in TNC secretion, show no major pathologies. We hypothesized that TNC-deficient mice would demonstrate defects in the repair of damaged leg muscles, which would be of functional significance because this tissue is subjected to frequent cycles of mechanical damage and regeneration. TNC-deficient mice demonstrated a blunted expression of the large TNC isoform and a selective atrophy of fast-muscle fibers associated with a defective, fast myogenic expression response to a damaging mechanical challenge. Transcript profiling mapped a set of de-adhesion, angiogenesis, and wound healing regulators as TNC expression targets in striated muscle. Expression of these regulators correlated with the residual expression of a damage-related 200-kDa protein, which resembled the small TNC isoform. Somatic knockin of TNC in fast-muscle fibers confirmed the activation of a complex expression program of interstitial and slow myofiber repair by myofiber-derived TNC. The results presented here show that a TNC-orchestrated molecular pathway integrates muscle repair into the load-dependent control of the striated muscle phenotype. PMID:18757758

  9. Deletion of muscle GRP94 impairs both muscle and body growth by inhibiting local IGF production

    PubMed Central

    Barton, Elisabeth R.; Park, SooHyun; James, Jose K.; Makarewich, Catherine A.; Philippou, Anastassios; Eletto, Davide; Lei, Hanqin; Brisson, Becky; Ostrovsky, Olga; Li, Zihai; Argon, Yair

    2012-01-01

    Insulin-like growth factors (IGFs) are critical for development and growth of skeletal muscles, but because several tissues produce IGFs, it is not clear which source is necessary or sufficient for muscle growth. Because it is critical for production of both IGF-I and IGF-II, we ablated glucose-regulated protein 94 (GRP94) in murine striated muscle to test the necessity of local IGFs for normal muscle growth. These mice exhibited smaller skeletal muscles with diminished IGF contents but with normal contractile function and no apparent endoplasmic reticulum stress response. This result shows that muscles rely on GRP94 primarily to support local production of IGFs, a pool that is necessary for normal muscle growth. In addition, body weights were ∼30% smaller than those of littermate controls, and circulating IGF-I also decreased significantly, yet glucose homeostasis was maintained with little disruption to the growth hormone pathway. The growth defect was complemented on administration of recombinant IGF-I. Thus, unlike liver production of IGF-I, muscle IGF-I is necessary not only locally but also globally for whole-body growth.—Barton, E. R., Park, S., James, J. K., Makarewich, C. A., Philippou, A., Eletto, D., Lei, H., Brisson, B., Ostrovsky, O., Li, Z., Argon, Y. Deletion of muscle GRP94 impairs both muscle and body growth by inhibiting local IGF production. PMID:22649033

  10. [Myokines - muscle tissue hormones].

    PubMed

    Stránská, Zuzana; Svačina, Štěpán

    2015-04-01

    Physical inactivity is demonstrably related to the manifestation of chronic diseases which significantly modify the quality and prognosis of life in a negative way. The benefits of exercise are surely mediated by many pathophysiological mechanisms interrelated in varying degrees, which have not yet been fully examined in their complexity. In the late 20th century it was positively proven that a working striated muscle really regulates the metabolic and physiological response in the other organs. These involve several hundred substances with autocrine, paracrine and endocrine effects. These proteins and peptides, if released into the blood stream, substantially affect the metabolism of distant organs. They were classified as "myokines" (cytokines produced by myocytes). The identified myokines include e.g. IL4, IL6, IL7, IL15, myostatin, LIF (leukemia inhibitory factor), BDNF (brain-derived neurotrophic factor), IGF1 (insulin-like growth factor), FGF2 (fibroblast growth factor 2), FGF21, FSTL1 (follistatin-related protein 1), irisin, EPO (erythropoetin) and BAIBA (β-aminoisobutyric acid). Myokines have first of all an immunoregulatory role in the human body. Another important effect of myokines is, coincidentally also in the interaction with adipose tissue, the regulation of energy homeostasis. They also affect the growth of muscle fibres and their regeneration, stimulate angiogenesis, they are involved in the regulation of glucose metabolism and have a proven effect on lipids. Considering their diverse function, myokines present a prospective therapeutic goal in the treatment of disorders of muscle growth and regeneration as well as obesity. Another recent research moves toward uncovering of the "myokine resistance" as a result of long-term muscle inactivity and its association with chronic subclinical inflammation. PMID:25894270