1,721,096 research outputs found
Neural control on the activity of the sarcoplasmic reticulum of rat skeletal muscle
No full textNeural control on the activity of the calcium-transport system in sarcoplasmic reticulum of rat skeletal muscle.
Margreth A, Salviati G, Carraro U.
Nature. 1973 Jan 26;241(5387):285-6. No abstract available.
PMID:
4267181
[PubMed - indexed for MEDLINE
Structural membrane proteins and loosely associated proteins of the sarcoplasmic reticulum
Full text linkBiochem J. 1974 Jun;139(3):509-13.
Structural membrane proteins and loosely associated proteins of the sarcoplasmic reticulum.
Margreth A, Carraro U, Salviati G.
Abstract
The protein composition of sarcoplasmic-reticulum vesicles, either unpurified or after fractionation on sucrose gradients, and with or without previous osmotic shock and sonication, was investigated by electrophoresis in acid polyacrylamide gels. The pattern of release of loosely bound proteins is discussed with respect to their localization in the interior of the vesicles.
PMID:
4369219
[PubMed - indexed for MEDLINE]
PMCID: PMC1166315
Free PMC Articl
Ca2+ release from sarcoplasmic reticulum of skinned fast and slow-twitch muscle fibers
No full textWe have performed a comparative study of Ca”+ release
rom the sarcoplasmic reticulum (SR) of chemically skinned
fibers from rabbit fast- and slow-twitch skeletal muscle. Ca
fluxes have been indirectly monitored by following either tension development or the inhibition of net Ca loading rate by
a light-scattering method. Several drugs (Ca-release modulators) have been used to either trigger or block Ca2+ release. Our results indicate that caffeine, doxorubicin, and ryanodine activate Ca release, whereas ruthenium red blocks Ca2+ release from both fast- and slow-twitch skinned fibers. Caffeine has greater affinity for slow SR, whereas doxorubicin, ruthenium red, and ryanodine have greater affinity for fast SR. Our results indicate that Ca”+-release mechanisms in fast and slow SR are homologous but not identical and that differences in twitch contraction time might be also related to the inherent properties of the Ca-release mechanism
HEMT ad alta mobilità e ad altissima larghezza di banda
No full textL’attività del progetto prosegue il lavoro svolto nelle precedenti collaborazioni bilaterali. Nell’ultima annualità in particolare è stato concluso lo studio di HEMTs basati su (Al)GaN prodotti in NTT, in accordo con lo sviluppo temporale originario del progetto. Durante il 2006 l’attività di ricerca è stata anche rivolta allo sviluppo di nuove collaborazioni con altri gruppi italiani e giapponesi, con particolare riguardo allo studio di nanomateriali di interesse comune ed allo sviluppo di metodologie d’indagine adatte alle nuove tematiche
Calcium-gated calcium channels in sarcoplasmic reticulum of rabbit skinned skeletal muscle fibers.
Full text linkThe action of ruthenium red (RR) on Ca2+ loading by and Ca2+ release from the sarcoplasmic reticulum (SR) of chemically skinned skeletal muscle fibers of the rabbit was investigated. Ca2+ loading, in the presence of the precipitating anion pyrophosphate, was monitored by a light-scattering method. Ca2+ release was indirectly measured by following tension development evoked by caffeine. Stimulation of the Ca2+ loading rate by 5 microM RR was dependent on free Ca2+, being maximal at pCa 5.56. Isometric force development induced by 5 mM caffeine was reversibly antagonized by RR. IC50 for the rate of tension rise was 0.5 microM; that for the extent of tension was 4 microM. RR slightly shifted the steady state isometric force/pCa curve toward lower pCa values. At 5 microM RR, the pCa required for half-maximal force was 0.2 log units lower than that of the control, and maximal force was depressed by approximately 16%. These results suggest that RR inhibited Ca2+ release from the SR and stimulated Ca2+ loading into the SR by closing Ca2+-gated Ca2+ channels. Previous studies on isolated SR have indicated the selective presence of such channels in junctional terminal cisternae
Polimorphism of myofibrillar proteins of rabbit skeletal muscle fibres. An electrophoretic study of single fibres
No full textRabbit predominantly fast-twitch-fibre and predominantly slow-twitch-fibre skeletal muscles of the hind limbs, the psoas, the diaphragm and the masseter muscles were fibre-typed by one-dimensional polyacrylamide-gel electrophoresis of the myofibrillar proteins of chemically skinned single fibres. Investigation of the distribution of fast-twitch-fibre and slow-twitch-fibre isoforms of myosin light chains and the type of myosin heavy chains, based on peptide 'maps' published in Cleveland. Fischer, Kirschner & Laemmli [(1977) J. Biol. Chem. 252, 1102-1106], allowed a classification of muscle fibres into four classes, corresponding to histochemical types I, IIA, IIB and IIC. Type I fibres with a pure slow-twitch-type of myosin were found to be characterized by a unique set of isoforms of troponins I, C and T, in agreement with the immunological data of Dhoot & Perry [(1979) Nature (London) 278, 714-718], by predominance of the beta-tropomyosin subunit and by the presence of a small amount of an additional tropomyosin subunit, apparently dissimilar from fast-twitch-fibre alpha-tropomyosin subunit. The myofibrillar composition of type IIB fast-twitch white fibres was the mirror image of that found for slow-twitch fibres in that the fast-twitch-fibre isoforms only of the troponin subunits were present and the alpha-tropomyosin subunit predominated. Type IIA fast-twitch red fibres showed a troponin subunit composition identical with that of type IIB fast-twitch white fibres. On the other hand, a unique type of myosin heavy chains was found to be associated with type IIA fibres. Furthermore, the myosin light-chain composition of these fibres was invariably characterized by a small amount of LC3F light chain and by a pattern that was either a pure fast-twitch-fibre light-chain pattern or a hybrid LC1F/LC2F/LC3F/LC1Sb light-chain pattern. By these criteria type IIA fibres could be distinguished from type IIC intermediate fibres, which showed coexistence of fast-twitch-fibre and slow-twitch-fibre forms of myosin light chains and of troponin subunits
Functional properties of innovative Nanosystems for Nanomedicine and Nanoelectronics (F3N)
No full textDuring the last five years, the interest of the international scientific community on innovative nanostructured materials increased exponentially. Only during 2012, more than 4400 papers having “nano” in the title have been published in international Journals (source ISI WEB of Science). In the frame of a previous cooperation, the Italian and Japanese teams involved in this project have been previously carried out a research activity with high level results (see the 5 significant papers published by the teams). On that basis the proposed F3N project will focus on the:
- synthesis and optimization at the nanoscale of functional nanosystems (e.g. SiC, Si, Ge, SiGe, ZnO nanowires-NWs) for nanomedicine
(cancer treatments and artificial retina) and bio-sensing applications as well as of SiC thin films for prosthetics
- defect evaluation and failure analysis of III-V- and Si-based optical and electronic devices
To optimize the NW properties, a methodological development of specific nanoscale characterization techniques will be carried out by complementing the know how and the advanced experimental set up of the Italian and Japanese teams
Inositol 1,4,5-trisphosphate induces calcium release from sarcoplasmic reticulum of skeletal muscle
No full textThe sarcoplasmic reticulum of skeletal muscle is a specialized form of endoplasmic reticulum that controls myoplasmic calcium concentration and, therefore, the contraction-relaxation cycle. Ultrastructural studies have shown that the sarcoplasmic reticulum is a continuous but heterogeneous membranous network composed of longitudinal tubules that surround myofibrils and terminal cisternae. These cisternae are junctionally associated, via bridging structures called 'feet', with sarcolemmal invaginations (the transverse tubules) to form the triadic junction. Following transverse tubule depolarization, a signal, transmitted along the triadic junction, triggers Ca2+ release from terminal cisternae, but the mechanism of this coupling is still unknown. Inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) has recently been shown to mobilize Ca2+ from intracellular stores, referable to endoplasmic reticulum, in a variety of cell types (see ref. 8 for review), including smooth muscle cells of the porcine coronary artery and canine cardiac muscle cells. Here we show that Ins(1,4,5)P3 releases Ca2+ from isolated, purified sarcoplasmic reticulum fractions of rabbit fast-twitch skeletal muscle, the effect being more pronounced on a fraction of terminal cisternae that contains morphologically intact feet structures; and elicits isometric force development in chemically skinned muscle fibres
Molecular and antigenic properties of cytochrome b5 from slow-muscle sarcoplasmic reticulum.
No full textNADH--cytochrome b5 reductase and cytochrome b5 associated with slow-muscle sarcoplasmic reticulum and liver microsomal fraction were identified with discrete protein bands of molecular weights 33000 and 16700 by polyacrylamide-gel electrophoresis. Purified detergent-extracted cytochrome b5 from muscle sarcoplasmic reticulum is indistinguishable from liver microsomal cytochrome b5 with respect to spectral properties, pI values and immunological reactivity with antibody to the liver cytochrome b5. Reaction of the antibody with membrane-bound cytochrome b5 inhibits the sarcoplasmic-reticulum NADH--cytochrome c reductase activity
Ca2+ channel agonist BAY-k 8644 does not elicit Ca2+ release from skeletal muscle sarcoplasmic reticulum
No full textBAY-k 8644, a nifedipine analogue, promotes Ca2+ influx into excitable cells via plasma membrane voltage-sensitive Ca2+ channels. We report here that sarcoplasmic reticulum (SR) Ca2+ release channels are insensitive to BAY-k 8644, as studied in highly purified isolated fractions and in chemically skinned fibers of rabbit skeletal muscle. This result suggests that a subcellular heterogeneity exists among Ca2+ channels, at least with respect to drug-receptor sites. In the course of this study, however we found that BAY-k 8644 reversibly inhibits the SR Ca2+ pump, i.e., it decreases Ca2+ influx into the SR lumen, although at concentrations (IC50 = 3-5 X 10(-5) M) much higher than those effective on voltage-sensitive Ca2+ channels
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