The distribution of the <i>T</i>‐system along the sarcomeres of frog and toad sartorius muscles

Peachey, Lee D.; Schild, Renée F.

doi:10.1113/jphysiol.1968.sp008405

Cited by 69 publications

(30 citation statements)

References 16 publications

(23 reference statements)

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“…A continuous tubule could result from the repeated caveolation. In addition, the developed T system in vivo is much more curved and branched than had generally been believed (see Peachey and Schild, 1968). It seems that the T-system tubules are straight only where they are connected with the SR membranes, i.e.…”

Section: Discussionmentioning

confidence: 70%

Formation of Elaborate Networks of T-System Tubules in Cultured Skeletal Muscle With Special Reference to the T-System Formation

Ishikawa

1968

The Journal of Cell Biology

237

109

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Muscle cells, cultured for 1-28 days from I 1-day chick embryo breast muscles, often show elaborate, three-dimensional networks of a membranous system. The network consists of tubular units which are quite regularly arranged. The tubular units composing the network are accessible to ferritin particles suspended in the culture medium; this suggests continuity with the extracellular fluid. These networks can be regarded as a special morphological elaboration of the T-system tubules. Such network formations can be seen much more often in well-developed myotubes. The networks usually exhibit a hexagonal pattern, which is formed of tubular units of a constant diameter. However, some early myotubes contain tetragonal networks, which are composed of spherical pockets with channels of lesser diameter connecting the pockets. Networks are also observed which probably represent a transitional form between these two patterns. Myotubes show many inpocketings of the sarcolemma similar to what are commonly referred to as caveolae or micropinocytotic vesicles. The similarity in configuration and dimension of the tubular units of the network to the caveolae leads to the plausible suggestion that repeated caveola-formation from the sarcolemma or T-system tubule may result in formation of these networks. In this connection, a possible mechanism of the T-system tubule formation is discussed.

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Section: Discussionmentioning

confidence: 70%

Formation of Elaborate Networks of T-System Tubules in Cultured Skeletal Muscle With Special Reference to the T-System Formation

Ishikawa

1968

The Journal of Cell Biology

237

109

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“…Since R 1 was calculated as being proportional to the T-system volume per unit fiber cross-section area in the lattice plane, to make R 1 equal to the resistivity of Ringer the T-system volume would have to be over three times lower than the value used. Although Peachey and Schild (1968) found that the fraction of the T-system volume accessible to ferritin might be as low as one-third, their estimate of the ferritin volume was a lower limit and they concluded that the entire T-system is probably accessible to ferritin and, therefore, presumably also to extracellular fluid. A high tubule internal resistivity would be consistent with the finding that the effective space constant of the T-system is shorter than can be explained on the basis of the tubule contents having the resistivity of Ringer solution (Adrian, Costantin, and Peachey, 1969).…”

Section: Imentioning

confidence: 99%

Linear Electrical Properties of the Transverse Tubules and Surface Membrane of Skeletal Muscle Fibers

Schneider

1970

The Journal of General Physiology

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With the use of two intracellular microelectrodes and a circuit designed to compensate for the effects of stray capacitances around the electrodes, transfer impedance measurements were made at frequencies from 0.5 to 1000 c/s on frog sartorius muscle fibers bathed in 7.5 mM K Ringer solution. Complete AC cable analyses performed at 46, 100, 215, 464, and 1000 c/s showed that the fibers behaved as ideal one-dimensional cables having purely resistive internal impedances (R = 102 4 11 I2 cm). Two circuits were considered for fiber inside-outside impedance, a four lumped parameter circuit and a parallel resistance and capacitance shunted by the input impedance of a lattice model for the T-system. Least squares fits to fiber input impedance phase angles were better with the latter circuit than with the former. With the use of the lattice model the specific capacitance of both the surface and transverse tubule membranes was found to be I uF/cm 2 and the internal resistivity of the tubules to be about 300 0f cm.The local activation experiments of Huxley and Taylor (1958) and of Huxley and Straub (1958) indicated that the transverse tubules of skeletal muscle fibers form the system which conducts the influence of surface membrane depolarization into the fiber for initiating contraction. Knowledge of the electrical properties of the structures in this system is consequently important for understanding excitation-contraction coupling. The experiments to be described were carried out to determine the passive linear electrical properties of both the T-system and surface membrane of frog muscle fibers.Impedance measurements made over a range of frequencies may provide a means of separating the T-system impedance from that of the surface membrane. Falk and Fatt (1964) demonstrated that the input impedance of frog 640

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“…EDL and SOL muscles were examined at 11 age points : newborn, 2,3,5,7,10,15,20,30,40, and 60 days old. The muscles were dissected and fixed slightly stretched on cork blocks in 6.2% glutaraldehyde in 0.1 M cacodylate buffer (pH 7 .2) containing 2 mm CaCI2 (26), washed in buffer with 10% added sucrose, and postfixed in 1 % osmium tetroxide with 2 mm CaC12 . In some cases the tissue was stained en bloc with uranyl acetate (18) .…”

Section: Methodsmentioning

confidence: 99%

Changes in the Sarcoplasmic Reticulum and Transverse Tubular System of Fast and Slow Skeletal Muscles of the Mouse During Postnatal Development

Luff

Atwood

1971

The Journal of Cell Biology

162

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The sarcoplasmic reticulum (SR) and transverse tubular system (TTS) of a fast-twitch muscle (extensor digitorum longus-EDL) and a slow-twitch muscle (soleus-SOL) of the mouse were examined during postnatal development . Muscles of animals newborn to 60 days old were fixed in glutaraldehyde and osmium tetroxide and examined with an electron microscope. At birth the few T tubules were often oriented longitudinally, but at the age of 10 days most of them had a transverse orientation . In the EDL, the estimated volume of the TTS increased from 0 .08% at birth to 0 .4% in the adult ; corresponding values for the SOL were 0 .04% at birth and 0.22% in the adult . A similar relative change was observed in surface area of the TTS during development . Calculated on the basis of a 30 µm diameter fiber, the surface area of the TTS in the EDL increased from 0 .60 cm2 TTS/cm2 fiber surface in the newborn to 3 .1 cm2 /cm2 in the adult, compared with 0.15 cm2 /cm2 at birth to 1 .80 cm2 /cm2 in the adult for the SOL . The SR in the newborn muscles occurred as a loose network of tubules that developed rapidly within the subsequent 20 days, especially at the I band level . The volume of the SR increased in the EDL from 1 .1 % of fiber volume at birth to 5 .5 % in the adult. In the SOL the change was from 1 .7 % to 2 .9 % . The SOL approached the adult values more rapidly than the EDL, although the EDL had more SR and T tubules . Fibers of both EDL and SOL muscles showed variation in Z line thickness, mitochondrial content, and diameter, but over-all differences between the two muscles in amount of SR and TTS were significant . It is considered that the differing amounts of SR and TTS are closely rela ted to the differing speeds of contraction that have been demonstrated for these two muscles .

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The distribution of the T‐system along the sarcomeres of frog and toad sartorius muscles

Cited by 69 publications

References 16 publications

Formation of Elaborate Networks of T-System Tubules in Cultured Skeletal Muscle With Special Reference to the T-System Formation

Formation of Elaborate Networks of T-System Tubules in Cultured Skeletal Muscle With Special Reference to the T-System Formation

Linear Electrical Properties of the Transverse Tubules and Surface Membrane of Skeletal Muscle Fibers

Changes in the Sarcoplasmic Reticulum and Transverse Tubular System of Fast and Slow Skeletal Muscles of the Mouse During Postnatal Development

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