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 THE SARCOPLASMIC RETICULUM AND TRANSVERSE TUBULES OF THE FROG'S SARTORIUS

1965 ◽  
Vol 25 (3) ◽  
pp. 209-231 ◽  
Author(s):  
Lee D. Peachey
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Surface Area ◽  
Osmium Tetroxide ◽  
Fiber Surface ◽  
Sartorius Muscle ◽  
Fiber Volume ◽  
Transverse Tubules ◽  
Contraction Coupling ◽  
Terminal Cisternae

The sarcoplasmic reticulum of the frog's sartorius muscle was examined by electron microscopy following sequential fixation in glutaraldehyde and osmium tetroxide and embedding in Epon. The earlier results of Porter and Palade on Ambystoma muscle were confirmed in the sartorius. In addition, the transverse tubules were observed to be continuous across the width of the fiber, a set of flat intermediate cisternae was seen to connect the terminal cisternae to the longitudinal tubules in the A band, and the continuous reticulum collar at the center of the A band was found to be perforated by circular and elongated pores (the fenestrated collar). The transverse tubules have a volume about 0.3 per cent of the fiber volume, and a surface area about 7 times the outer cylindrical surface area for a fiber 100 µ in diameter. The terminal cisternae, the intermediate cisternae, and the longitudinal tubules together with the fenestrated collar each have a volume of 4 to 5 per cent of the fiber volume and a surface area 40 to 50 times the outer surface area of a fiber 100 µ in diameter. Some evidence for continuity of the transverse tubules with the fiber surface is presented, but this is thought to be not so convincing as evidence presented by others. The results are discussed in terms of a possible mechanism for a role of the transverse tubules and sarcoplasmic reticulum in excitation-contraction coupling, as suggested by their morphology and a variety of physiological studies. In this scheme, the transverse tubules are thought to be electrically coupled to the terminal cisternae, so that depolarization of the fiber surface spreads inward along the transverse tubules and to the terminal cisternae, initiating the release of a contraction-activating substance.

scholarly journals The Intracellular Site of Calcium Activation of Contraction in Frog Skeletal Muscle

1970 ◽  
Vol 55 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Saul Winegrad
Keyword(s):  
Skeletal Muscle ◽  
Room Temperature ◽  
Half Time ◽  
Frog Skeletal Muscle ◽  
Calcium Efflux ◽  
Transverse Tubules ◽  
Calcium Activation ◽  
Thin Filaments ◽  
Almost All ◽  
Terminal Cisternae

Radioautography has been used to localize 45Ca in isotopically labeled frog skeletal muscle fibers which had been quickly frozen during a maintained tetanus, a declining tetanus, or during the period immediately following a tetanus or a contracture. During a tetanus almost all of the myofibrillar 45Ca is localized in the region of the sarcomere occupied by the thin filaments. The amount varies with the tension being developed by the muscle. The movement of calcium within the reticulum from the tubular portion to the terminal cisternae during the posttetanic period has a half-time of about 9 sec at room temperature and a Q10 of about 1.7. Repolarization is not necessary for this movement. Evidence is given to support the notion that most calcium efflux from the cell occurs from the terminal cisternae into the transverse tubules.

Fusion of Sarcoplasmic Reticulum with Ruthenium Red

1975 ◽  
Vol 33 ◽  
pp. 500-501
Author(s):  
N. Wallace ◽  
J.R. Sommer
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Membrane Fusion ◽  
Extracellular Space ◽  
Ruthenium Red ◽  
Frog Skeletal Muscle ◽  
Definition Of ◽  
Terminal Cisternae ◽  
Structural Definition

Howell recently reported the effect of Ruthenium Red (RR) on the sarcoplasmic reticulum (SR) of frog skeletal muscle after long exposures to that dye. Howell observed staining of the junctional granules within the junctional SR (terminal cisternae), and fusion of the so-called intermediate cisternae that are intercalated between junctional and free SR. This is an important observation because it may provide, first, needed additional evidence for a structural definition of the so-called intermediate cisterna, and second, the fusion of the intermediate cisternae under these circumstances suggests that they might have properties that are different from, or in addition to those of the junctional and free SR, respectively. For example, membrane fusion in that region might conceivably occur in vivo under certain circumstances in which case a large proportion of the SR might become separated, electrically, from the junctional SR. As a result, at least temporary openings of the junctional SR to the extracellular space remain a possibility even during depolarization.

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.

Filipin-Sterol-Complexes in Finch and Mouse Cardiac Muscle

1981 ◽  
Vol 39 ◽  
pp. 504-505
Author(s):  
J. R. Sommer
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Sarcoplasmic Reticulum ◽  
Cardiac Muscle ◽  
Plasma Membranes ◽  
Frog Skeletal Muscle ◽  
Transverse Tubules ◽  
Topographic Features ◽  
Terminal Cisterna ◽  
Close Proximity

We have recently reported that in frog skeletal muscle the plasma membranes, including the transverse tubules, are densely populated by filipin-sterol-complexes (FC), and that in the sarcoplasmic reticulum (SR) the FC are found much less commonly than in the plasma membrane, but that they have a predilection for the junctional SR (terminal cisterna) which in skeletal muscle are very large cisternae that are in close proximity to the plasma membrane. The analogous junctional SR of cardiac muscle shares all anatomical and topographic features with the junctional SR of skeletal muscle, except that in the latter the junctional SR is much larger. Ue have considered the possibility that the proximity of the junctional SR to the plasma membrane, the latter being replete with FC, may be related to the predilection of the FC for junctional SR in skeletal muscle.

Ultra-Rapid Freezing of Isolated Skeletal Muscle Fibers

1977 ◽  
Vol 35 ◽  
pp. 576-577
Author(s):  
Joachim R. Sommer ◽  
Nancy R. Wallace
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Granular Material ◽  
Nuclear Envelope ◽  
Intracellular Calcium ◽  
Ruthenium Red ◽  
Threshold Concentration ◽  
Rapid Freezing ◽  
Frog Skeletal Muscle ◽  
Electrical Isolation

After Howell (1) had shown that ruthenium red treatment of fixed frog skeletal muscle caused collapse of the intermediate cisternae of the sarcoplasmic reticulum (SR), forming a pentalaminate structure by obi iterating the SR lumen, we demonstrated that the phenomenon involves the entire SR including the nuclear envelope and that it also occurs after treatment with other cations, including calcium (2,3,4).From these observations we have formulated a hypothesis which states that intracellular calcium taken up by the SR at the end of contraction causes the M rete to collapse at a certain threshold concentration as the first step in a subsequent centrifugal zippering of the free SR toward the junctional SR (JSR). This would cause a) bulk transport of SR contents, such as calcium and granular material (4) into the JSR and, b) electrical isolation of the free SR from the JSR.

Electron Probe Analysis of Muscle

1982 ◽  
Vol 40 ◽  
pp. 398-401
Author(s):  
A. V. Somlyo ◽  
H. Shuman ◽  
A. P. Somlyo
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Resting State ◽  
Binding Sites ◽  
Electron Probe ◽  
Frog Skeletal Muscle ◽  
Electron Probe Analysis ◽  
Probe Analysis

Electron probe analysis of frozen dried cryosections of frog skeletal muscle, rabbit vascular smooth muscle and of isolated, hyperpermeab1 e rabbit cardiac myocytes has been used to determine the composition of the cytoplasm and organelles in the resting state as well as during contraction. The concentration of elements within the organelles reflects the permeabilities of the organelle membranes to the cytoplasmic ions as well as binding sites. The measurements of [Ca] in the sarcoplasmic reticulum (SR) and mitochondria at rest and during contraction, have direct bearing on their role as release and/or storage sites for Ca in situ.

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