Distribution of Filipin in Skeletal Muscle Membranes

1980 ◽  
Vol 38 ◽  
pp. 628-629
Author(s):  
J.R. Sommer ◽  
P.C Dolber ◽  
N.R. Wallace
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Lipid Droplets ◽  
Polyene Antibiotic ◽  
Transverse Tubules ◽  
Single Form

Filipin, a polyene antibiotic, forms complexes (FC) with cholesterol-like substances (1,2). These complexes were visible by EM as "caveolae" either in clusters or singly (cf.Figs.1,3). They covered the entire plasmalemma, including the transverse tubules (TT) and were present in some mitochondria, at the edges of lipid droplets, and in the sarcoplasmic reticulum (SR).In the SR they were found mainly in the intermediate cisternae (IC),chiefIy in the form of clusters (Fig.3) which were often in register with N lines. FCs were significantly less common in the junctional SR and free SR, where, as in the plasmalemma, they were more likely to be in the single form (Fig.2A). This distribution varied somewhat from fiber to fiber, but not within a sin-gle fiber, nor within 1 or 4 hrs exposure to Filipin.

scholarly journals Sizes of components in frog skeletal muscle measured by methods of stereology.

1975 ◽  
Vol 66 (1) ◽  
pp. 31-45 ◽  
Author(s):  
B A Mobley ◽  
B R Eisenberg
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Surface Area ◽  
Volume Ratio ◽  
Sartorius Muscle ◽  
Morphological Parameters ◽  
Frog Skeletal Muscle ◽  
Fiber Volume ◽  
Transverse Tubules ◽  
Terminal Cisternae

Stereological techniques of point and intersection counting were used to measure morphological parameters from light and electron micrographs of frog skeletal muscle. Results for sartorius muscle are as follows: myofibrils comprise 83% of fiber volume; their surface to volume ratio is 3.8 mum-1. Mitochondria comprise 1.6% of fiber volume. Transverse tubules comprise 0.32% of fiber volume, and their surface area per volume of fiber is 0.22 mum-1. Terminal cisternae of the sarcoplasmic reticulum comprise 4.1% of fiber volume; their surface area per volume of fiber is 0.54 mum-1. Longitudinal sarcoplasmic reticullum comprises 5.0% of fiber volume, and its surface area per volume of fiber is 1.48 mum-1. Longitudinal bridges between terminal cisternae on either side of a Z disk were observed infrequently; they make up only 0.035% of fiber volume and their surface area per volume of fiber is 0.009 mum-1. T-SR junction occurs over 67% of the surface of transverse tubules and over 27% of the surface of terminal cisternae. The surface to volume ratio of the caveolae is 48 mum-1; caveolae may increase the sarcolemmal surface area by 47%. Essentially the same results were obtained from semitendinosus fibers.

scholarly journals A proposed role for non-junctional transverse tubules in skeletal muscle as flexible segments allowing expansion of the transverse network

2019 ◽  
Vol 29 (2) ◽  
Author(s):  
Manuela Lavorato ◽  
Ramesh Iyer ◽  
Clara Franzini-Armstrong
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Skeletal Muscles ◽  
Sarcomere Length ◽  
Muscle Fibers ◽  
Entire Length ◽  
Small Fish ◽  
Transverse Tubules ◽  
T Tubules

Using a variety of technical approaches, we have detected the presence of continuous triads that cover the entire length of T tubules in the main white body muscles of several small fish. This is in contrast to the discontinuous association of sarcoplasmic reticulum with T tubules in the red muscles from the same fish as well as in all other previously described muscles in a large variety of skeletal muscles. We suggest that continuous triads are permissible only in muscle fibers that are not normally subject to significant changes in sarcomere length during normal in vivo activity, as is the case for white muscles in the trunk of fish.

Mechanisms of stimulated 45Ca efflux in skinned skeletal muscle fibers

1987 ◽  
Vol 65 (4) ◽  
pp. 632-641 ◽  
Author(s):  
Elizabeth W. Stephenson
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Calcium Release ◽  
Isometric Force ◽  
Signal Transmission ◽  
Transverse Tubules ◽  
Transverse Tubule ◽  
Ion Gradients ◽  
Charge Movements ◽  
Stimulation Of

Excitation–contraction (E–C) coupling in skeletal muscle can be studied in skinned fibers by direct assay of 45Ca efflux and simultaneous isometric force, under controlled conditions. Recent work provides evidence that such studies can address major current questions about the mechanisms of signal transmission between transverse tubules and sarcoplasmic reticulum and sarcoplasmic reticulum calcium release, as well as operation of the sarcoplasmic reticulum active Ca transport system in situ. Stimulation by imposed ion gradients at constant [K+][Cl−] product results in 45Ca release with two components: a large Ca2+-dependent efflux, responsible for contractile activation, and a small Ca2+-insensitive efflux. The Ca2+-insensitive stimulation is sustained, consistent with sustained depolarization, and appears to gradate the Ca2+-dependent stimulation; this component is likely to reflect intermediate steps in E–C coupling. Several lines of evidence suggest that the depolarizing stimulus acts on the transverse tubules. It is inhibited by the impermeant glycoside ouabain applied before skinning, which should specifically inhibit polarization of subsequently sealed transverse tubules. Sealed polarized transverse tubules also are the only plausible target for stimulation of 45Ca release by monensin and gramicidin D, which can rapidly dissipate Na+ and K+ gradients; a protonophore and the K+-specific ionophore valinomycin are ineffective, lonophore stimulation is prevented by the permeant glycoside digitoxin; it is also highly Ca2+ dependent. Stimulation of 45Ca release by imposed ion gradients is potentiated by perchlorate, which potentiates charge movements and activation in intact fibers, and is inhibited selectively in highly stretched fibers, presumably by transverse tubule – sarcoplasmic reticulum uncoupling. These results relate the Ca2+-dependent sarcoplasmic reticulum efflux channel to the physiological transverse tubule – sarcoplasmic reticulum coupling pathway, which also could involve Ca2+.

scholarly journals JARINGAN OTOT RANGKA Sistem membran dan struktur halus unit kontraktil

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Sunny Wangko
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Connective Tissue ◽  
Muscle Tissue ◽  
Muscle Fibers ◽  
Membrane System ◽  
Transverse Tubules ◽  
Foot Structure ◽  
Cross Bridges ◽  
Main Components

Abstract: There are three main components of skeletal muscle: connective tissue, muscle tissue, and membrane system. The connective tissue protects the muscle fibers and separate them into fasicles. The skeletal muscle consists of paralel muscle fibers with their myofibrils which are composed by smaller contractile units, thick myofilaments and thin myofilaments. The membrane system consists of sarcolemma, transverse tubules (TT), foot structure, and sarcoplasmic reticulum (SR) with its cisternae. Depolarization of the sarcolemma spreads to TT, foot structure, and SR, resulting in the release of Ca2+ ions from SR. These ions trigger the formation of cross bridges to begin a contraction.Keywords: sarcolemma, T tubule, sarcoplasmic reticulum, thick myofilament, thin myofilamentAbstrak: Terdapat tiga komponen utama jaringan otot rangka, yaitu: jaringan ikat, jaringan otot seran lintang, dan sistem membran. Jaringan ikat berfungsi melindungi serat-serat otot dan memisahkannya atas berkas-berkas otot. Jaringan otot rangka tersusun atas serat-serat otot yang bherjalan sejajar dengan miofibrilnya yang terdiri atas unit kontraktil yang lebih kecil yaitu miofilamen tebal dan tipis. Sistem membran terdiri atas sarkolema dimana terjadinya depolarisasi yang paling awal dan dihantarkan ke dalam serat otot melalui tubulus T, struktur kaki pada daerah triad, dan sisterna terminalis yang selanjutnya memicu pelepasan ion Ca2+ dari retikulum sarkoplasma. Ion Ca2+ merupakan pemicu untuk pembentukan jembatan silang yang mengawali suatu kontraksi otot.Kata kunci: sarkolema, tubulus T, retikulum sarkoplasma, filamen tebal, filamen tipis

Transport pathway, maturation, and targetting of the vesicular stomatitis virus glycoprotein in skeletal muscle fibers

1996 ◽  
Vol 109 (6) ◽  
pp. 1585-1596
Author(s):  
P. Rahkila ◽  
A. Alakangas ◽  
K. Vaananen ◽  
K. Metsikko
Keyword(s):  
Skeletal Muscle ◽  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Vesicular Stomatitis Virus ◽  
Muscle Fibers ◽  
Viral Glycoprotein ◽  
Transverse Tubules ◽  
Skeletal Muscle Fibers ◽  
Vesicular Stomatitis ◽  
Terminal Cisternae

We have infected isolated skeletal muscle fibers with the vesicular stomatitis virus or the mutant tsO45, whose glycoprotein is blocked in the endoplasmic reticulum at 39 degrees C. Immunofluorescence analysis for the viral glycoprotein indicated that the fibers were infected over their entire length at a virus dose of 10(9)/ml. When we infected the myofibers with the tsO45 mutant at 39 degrees C, the viral glycoprotein appeared to be localised to the terminal cisternae of the sarcoplasmic reticulum. Upon shifting the cultures to the permissive temperature, 32 degrees C, in the presence of dinitrophenol, which blocks vesicular transport, the viral glycoprotein proceeded to completely fill the sarcoplasmic reticulum. Thus, both the endoplasmic reticulum located at the terminal cisternae of the sarcoplasmic reticulum, and the entire endoplasmic and sarcoplasmic reticulum appeared to be continuous. Shifting the culture temperature from 39 degrees C to 20 degrees C, resulted in prominent perinuclear staining throughout the fibers, accompanied by the appearance of distinct bright dots between the nuclei. Electron microscopic immunoperoxidase labeling indicated that these bright structures represented the Golgi apparatus. When either the tsO45-infected or wild-type virus-infected fibers were incubated at 32 degrees C, the viral glycoprotein showed a staining pattern that consisted of double rows of punctate fluorescence. Immunogold labeling showed that the viral glycoprotein was present in both the transverse tubules as well as the endoplasmic/sarcoplasmic reticulum endomembranes. In addition, extensive viral budding was observed in the transverse tubules. Metabolic labeling experiments revealed that only half of the glycoprotein was processed in the Golgi, and this processed form had become incorporated into the budding viral particles. Thus, the processed viral glycoprotein was targeted to the transverse tubules. The other half of the glycoprotein remained endoglycosidase H-sensitive, suggesting its retention in the endoplasmic/sarcoplasmic reticulum endomembranes.

Biochemical characteristics of free and junctional sarcoplasmic reticulum and of transverse tubules in human skeletal muscle

1989 ◽  
Vol 12 (4) ◽  
pp. 323-331 ◽  
Author(s):  
Ernesto Damiani ◽  
Alfredo Barillari ◽  
Gianantonio Tobaldin ◽  
Sandra Pierobon ◽  
Alfredo Margreth
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Human Skeletal Muscle ◽  
Transverse Tubules ◽  
Biochemical Characteristics ◽  
Junctional Sarcoplasmic Reticulum
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