Myofilament overlap in swimming carp. I. Myofilament lengths of red and white muscle

1991 ◽  
Vol 260 (2) ◽  
pp. C283-C288 ◽  
Author(s):  
A. A. Sosnicki ◽  
K. E. Loesser ◽  
L. C. Rome
Keyword(s):  
Actin Filaments ◽  
Sarcomere Length ◽  
White Muscle ◽  
Frog Muscle ◽  
Myosin Filament ◽  
Thin Filaments ◽  
Thin Sections ◽  
Myosin Filaments ◽  
Tension Curve ◽  
Red And White Muscles

To assess myofilament overlap during locomotion, we estimated the length of myosin and actin filaments in axial red and white muscle of carp. Myosin filament lengths were 1.52 +/- 0.009 and 1.50 +/- 0.037 micron (means +/- SD) in the red and white muscle, respectively, as measured from thin sections. After correction for shrinkage (using the troponin-based 385-A axial periodicity), thin filaments were 0.96 +/- 0.009 and 0.97 +/- 0.023 micron in the red and white muscles, respectively. Filaments were also isolated from the white muscle and negatively stained. Myosin filaments were 1.56 +/- 0.025 microns, and actin filaments were 0.99 +/- 0.024 micron in length. The data from thin sections and isolated filaments agreed within 2% for actin and 4% for myosin filaments. The number of actin filament periods (24 for the red and white muscle) and the length of the filaments are the same as in frog. This suggests that the classic sarcomere length-tension curve of frog muscle may be used to estimate the functional properties of carp red and white muscle.

Band Patterns in Chick Muscle at Short Sarcomere Length

1970 ◽  
Vol 28 ◽  
pp. 144-145
Author(s):  
M. Hagopian ◽  
D. Spiro ◽  
P. Yau
Keyword(s):  
Electron Microscopy ◽  
Actin Filaments ◽  
Sarcomere Length ◽  
Pectoral Muscle ◽  
Thin Filaments ◽  
Thick Filaments ◽  
Myosin Filaments ◽  
Contraction Band

Glycerinated chick pectoral muscle was prepared for electron microscopy. Sarcomere lengths varied from 2.3 to 1.1μ reflecting various degrees of shortening. Over a sarcomere range of 2.3 to 1.3μ the thin actin filaments which measure 1.0μ and the thick myosin filaments which measure 1.5μ are constant in length (Fig. 1). At sarcomere lengths below 2μ the thin filaments penetrate through the center of the A band into the opposite halves of the sarcomere producing A contraction bands as previously described. In sarcomeres which measure 1.5 to 1.3μ additional contraction bands are noted adjacent to the Z lines. In longitudinal sections the array of filaments in the Z contraction band appears orderly (Fig. 2). It is our impression that these Z contraction bands result from penetration of the tapered lateral ends of the myosin filaments through the Z lines into the adjacent sarcomere rather than a crumpling of thick filaments as has been previously stated. Below 1.3μ in length the sarcomeres are disorganized, and it is not possible to define filament lengths.

scholarly journals Connectin filaments in stretched skinned fibers of frog skeletal muscle.

1984 ◽  
Vol 99 (4) ◽  
pp. 1391-1397 ◽  
Author(s):  
K Maruyama ◽  
H Sawada ◽  
S Kimura ◽  
K Ohashi ◽  
H Higuchi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Electron Microscopic ◽  
Thin Filaments ◽  
Thin Sections ◽  
Cytoskeletal Structure ◽  
Present Information ◽  
Sds Page ◽  
Myosin Filaments ◽  
Elastic Protein ◽  
Passive Stretch

Indirect immunofluorescence microscopy of highly stretched skinned frog semi-tendinous muscle fibers revealed that connectin, an elastic protein of muscle, is located in the gap between actin and myosin filaments and also in the region of myosin filaments except in their centers. Electron microscopic observations showed that there were easily recognizable filaments extending from the myosin filaments to the I band region and to Z lines in the myofibrils treated with antiserum against connectin. In thin sections prepared with tannic acid, very thin filaments connected myosin filaments to actin filaments. These filaments were also observed in myofibrils extracted with a modified Hasselbach-Schneider solution (0.6 M KCl, 0.1 M phosphate buffer, pH 6.5, 2 mM ATP, 2 mM MgCl2, and 1 mM EGTA) and with 0.6 M Kl. SDS PAGE revealed that connectin (also called titin) remained in extracted myofibrils. We suggest that connectin filaments play an important role in the generation of tension upon passive stretch. A scheme of the cytoskeletal structure of myofibrils of vertebrate skeletal muscle is presented on the basis of our present information of connectin and intermediate filaments.

scholarly journals Supercontracted state of vertebrate smooth muscle cell fragments reveals myofilament lengths.

1990 ◽  
Vol 111 (6) ◽  
pp. 2451-2461 ◽  
Author(s):  
J V Small ◽  
M Herzog ◽  
M Barth ◽  
A Draeger
Keyword(s):  
Smooth Muscle ◽  
Actin Filaments ◽  
Cytoskeletal Proteins ◽  
Terminal Phase ◽  
Myosin Filament ◽  
Protein Loss ◽  
Whole Cells ◽  
Myosin Filaments ◽  
Central Bundle ◽  
Cell Fragments

Isolated cell preparations from chicken gizzard smooth muscle typically contain a mixture of cell fragments and whole cells. Both species are spontaneously permeable and may be preloaded with externally applied phalloidin and antibodies and then induced to contract with Mg ATP. Labeling with antibodies revealed that the cell fragments specifically lacked certain cytoskeletal proteins (vinculin, filamin) and were depleted to various degrees in others (desmin, alpha-actinin). The cell fragments showed a unique mode of supercontraction that involved the protrusion of actin filaments through the cell surface during the terminal phase of shortening. In the presence of dextran, to minimize protein loss, the supercontracted products were star-like in form, comprising long actin bundles radiating in all directions from a central core containing myosin, desmin, and alpha-actinin. It is concluded that supercontraction is facilitated by an effective uncoupling of the contractile apparatus from the cytoskeleton, due to partial degradation of the latter, which allows unhindered sliding of actin over myosin. Homogenization of the cell fragments before or after supercontraction produced linear bipolar dimer structures composed of two oppositely polarized bundles of actin flanking a central bundle of myosin filaments. Actin filaments were shown to extend the whole length of the bundles and their length averaged integral to 4.5 microns. Myosin filaments in the supercontracted dimers averaged 1.6 microns in length. The results, showing for the first time the high actin to myosin filament length ratio in smooth muscle are readily consistent with the slow speed of shortening of this tissue. Other implications of the results are also discussed.

scholarly journals Unidirectional sliding of myosin filaments along the bundle of F-actin filaments spontaneously formed during superprecipitation.

1985 ◽  
Vol 101 (6) ◽  
pp. 2335-2344 ◽  
Author(s):  
S Higashi-Fujime
Keyword(s):  
Actin Filament ◽  
Actin Filaments ◽  
Room Temperature ◽  
The Other ◽  
Reverse Direction ◽  
Myosin Filament ◽  
Bipolar Structure ◽  
Myosin Filaments ◽  
Direction Of Movement ◽  
Cold Spring

I reported previously (Higashi-Fujime, S., 1982, Cold Spring Harbor Symp. Quant. Biol., 46:69-75) that active movements of fibrils composed of F-actin and myosin filaments occurred after superprecipitation in the presence of ATP at low ionic strengths. When the concentration of MgCl2 in the medium used in the above experiment was raised to 20-26 mM, bundles of F-actin filaments, in addition to large precipitates, were formed spontaneously both during and after superprecipitation. Along these bundles, many myosin filaments were observed to slide unidirectionally and successively through the bundle, from one end to the other. The sliding of myosin filaments continued for approximately 1 h at room temperature at a mean rate of 6.0 micron/s, as long as ATP remained in the medium. By electron microscopy, it was found that most F-actin filaments decorated with heavy meromyosin pointed to the same direction in the bundle. Myosin filaments moved actively not only along the F-actin bundle but also in the medium. Such movement probably occurred along F-actin filaments that did not form the bundle but were dispersed in the medium, although dispersed F-actin filaments were not visible under the microscope. In this case, myosin filament could have moved in a reverse direction, changing from one F-actin filament to the other. These results suggested that the direction of movement of myosin filament, which has a bipolar structure and the potentiality to move in both directions, was determined by the polarity of F-actin filament in action.

A comparison of isolated and in situ thick filaments from smooth muscle

1986 ◽  
Vol 44 ◽  
pp. 156-157
Author(s):  
E.L. Buhle ◽  
A.V. Somlyo ◽  
A.P. Somlyo
Keyword(s):  
Smooth Muscle ◽  
Actin Filaments ◽  
Muscle Actin ◽  
Thin Sections ◽  
Ultrastructural Studies ◽  
Thick Filaments ◽  
Myosin Filaments ◽  
Rabbit Portal Vein ◽  
Stable Structures

Early ultrastructural studies of smooth muscle are consistent with the sliding filament mechanism of contraction. Myosin filaments are stable structures in situ and can be found in both relaxed and contracted muscle. Actin filaments can be decorated with SI subfragments of myosin to show a polarity similar to the Z-lines of skeletal muscle. The work presented here is a comparison of isolated thick filaments from relaxed chick amnion with thick filaments obtained in situ from longitudinal thin sections (∽50nm thick) of rabbit portal vein in rigor.

Cardiac physiology

2010 ◽  
pp. 2618-2627
Author(s):  
Rhys Evans ◽  
Kenneth T. MacLeod ◽  
Steven B. Marston ◽  
Nicholas J. Severs ◽  
Peter H. Sugden
Keyword(s):  
Actin Filaments ◽  
Ventricular Myocytes ◽  
Conduction System ◽  
The Body ◽  
Contractile Apparatus ◽  
Thin Filaments ◽  
Atp Production ◽  
Myosin Filaments ◽  
T Tubules ◽  
The Moment

The function of the heart is to provide the tissues of the body with sufficient oxygenated blood and metabolites to meet the moment-to-moment needs as dictated by physical activity and postural and emotional changes. Cardiac myocytes are the contractile cells of the heart and constitute the bulk of heart mass. There are differences between the myocytes of the ventricles, the atria, and the conduction system: ventricular myocytes are elongated cells, packed with myofibrils (the contractile apparatus) and mitochondria (for ATP production). Myofibrils are repeating units (sarcomeres) made up of thin actin filaments anchored at the Z-discs at either end of the sarcomere, and thick myosin filaments which interdigitate and interact with the thin filaments. Contraction results from sarcomere shortening produced by the ATP-dependent movement of the thin and thick filaments relative to one another. Transverse (T-) tubules facilitate extracellular Ca...

scholarly journals Exercise Training in Skeletal Muscle of Brook Trout (Salvelinus Fontinalis)

1980 ◽  
Vol 87 (1) ◽  
pp. 177-194
Author(s):  
IAN A. JOHNSTON ◽  
THOMAS W. MOON
Keyword(s):  
Exercise Training ◽  
Enzyme Activities ◽  
Brook Trout ◽  
White Muscle ◽  
Salvelinus Fontinalis ◽  
Glycolytic Enzyme ◽  
Fish Swimming ◽  
Thin Sections ◽  
Red Muscle ◽  
Red And White Muscles

1. The differentiation of myotomal muscles in the brook trout (Salvelinus fontinalis Mitchill) has been investigated using p-phenylene diamine stained semi-thin sections and cytochemical and quantitative determinations of enzyme activities. 2. Evidence is presented that the range of fibre size in white muscle represents stages in growth rather than distinct fibre types. 3. Electromyography shows that both red and white muscles are recruited for sustained swimming. The threshold swimming speed for recruitment of white fibres is around 1·8 body length/s (L/s). 4. White muscle citrate synthetase and cytochrome oxidase activities are 25–35% that of red muscle. Hexokinase, phosphorylase and phosphofructo-kinase activities are 2, 4 and 2 times higher in white than red muscles. It is considered that the aerobic capacity of white muscle is sufficient to support sustained swimming, and that blood glucose could be an important fuel source. 5. Endurance exercise training has been investigated in fish swimming, continuously, for 21 days at 3 L/s. This training regime restricts spontaneous high-speed swimming activity and resulted in a general decline of white muscle glycolytic enzyme activities. Red fibres underwent hyper-trophy relative to non-exercised controls (530 ± 64 μm2 non-exercised, 901 ± 63 μm2 trained). Aerobic enzyme activities in red muscle and the fraction of fibre volume occupied by mitochondria (30·2 ± 0·8%) did not change in response to the training programme, but glycolytic enzyme activities were elevated. 3-OH Acyl CoA dehydrogenase activities increased in both red and white muscles indicating an enhanced capacity for fatty acid catabolism with training. 6. Plasma and muscle lactate levels were not statistically different between tank-rested and trained fish swimming at 3 L/s. 7. Adaptations of fish muscle to endurance training are discussed and compared with results for other vertebrates.

Changes in Striated Muscle Fibres During Contraction and Growth with Particular Reference to Myofibril Splitting

1971 ◽  
Vol 9 (1) ◽  
pp. 123-137
Author(s):  
G. GOLDSPINK
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Actin Filaments ◽  
Sarcomere Length ◽  
Biceps Brachii ◽  
Hexagonal Lattice ◽  
Muscle Fibres ◽  
Cross Sectional ◽  
Tension Development ◽  
Transverse Tubular System ◽  
Myosin Filaments

Ultrastructural measurements were carried out on the mouse biceps brachii and soleus muscles fixed at different states of contraction and stretch. At a sarcomere length of 2.7-2.9 µm the more peripheral actin filaments ran slightly obliquely from the Z-disk to the A-band. This is due to a mismatch between the rhombic actin lattice at the Z-disk and the hexagonal lattice at the M-line. For a perfect transformation of a rhombic lattice into a hexagonal lattice the ratio of the lattice spacings has to be 1:1.51. However, at this sarcomere length the ratio is about 1:2.0 (Z:M). During contraction the angle of the peripheral actin filaments remains approximately the same because the expansion of the M lattice is compensated for, partly by an increase in the Z-lattice spacing and partly by the bowing of the peripheral myosin filaments. When the sarcomeres are stretched beyond 3.0 µm the myosin filaments straighten out and the Z:M ratio decreases. The ratio of 1:1.51 is almost attained when there is no overlap of the actin and myosin filaments. Ultrastructural measurements were also carried out on biceps brachii muscles of different ages. The lattice spacings for a standard sarcomere length did not change during the post-natal growth period. The amount of myofibrillar material and sarcoplasmic reticulum plus transverse tubular system were estimated using linear analysis for muscles at 3 different stages of growth. It was found that the myofibrillar cross-sectional area in an individual muscle fibre may increase 40-fold during growth and that the transverse tubular and sarcoplasmic reticulum systems increase at about the same rate. In both the biceps brachii and the soleus muscles the myosin and actin filaments are not built into a continuous mass but they are divided into numerous discrete myofibrils. Subdivision of the myofibril mass occurs because the myofibrils split once they attain a certain size. The evidence presented in this paper supports the suggestion that the longitudinal splitting of the myofibrils occurs by the ripping of the Z-disks. When tension is rapidly developed by 2 adjacent sarcomeres a stress is produced at the centre of the Z-disk resulting from the oblique pull of the actin filaments. This causes some of the Z-disk filaments to rip and the rip then extends across the disk with the direction of the weave of the lattice. Evidence for the mechanism includes electron-micrographs showing Z-disks that are apparently just commencing to split; in these cases a hole can be seen in the centre of the disk. A model experiment is described which demonstrates the importance of the rate of tension development in causing myofibril splitting. Rapid tension development produces a snatch effect which causes the Z-disk filaments to break more readily. This may explain why the myofibrils in fast muscles tend to be small and discrete whilst those in slow muscles are larger and more irregular in shape.

scholarly journals Myosin filament polymerization and depolymerization in a model of partial length adaptation in airway smooth muscle

2011 ◽  
Vol 111 (3) ◽  
pp. 735-742 ◽  
Author(s):  
Gijs Ijpma ◽  
Ahmed M. Al-Jumaily ◽  
Simeon P. Cairns ◽  
Gary C. Sieck
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Actin Filaments ◽  
Isometric Force ◽  
Myosin Filament ◽  
Shortening Velocity ◽  
Partial Length ◽  
Myosin Filaments ◽  
Generating Capacity ◽  
Length Changes

Length adaptation in airway smooth muscle (ASM) is attributed to reorganization of the cytoskeleton, and in particular the contractile elements. However, a constantly changing lung volume with tidal breathing (hence changing ASM length) is likely to restrict full adaptation of ASM for force generation. There is likely to be continuous length adaptation of ASM between states of incomplete or partial length adaption. We propose a new model that assimilates findings on myosin filament polymerization/depolymerization, partial length adaptation, isometric force, and shortening velocity to describe this continuous length adaptation process. In this model, the ASM adapts to an optimal force-generating capacity in a repeating cycle of events. Initially the myosin filament, shortened by prior length changes, associates with two longer actin filaments. The actin filaments are located adjacent to the myosin filaments, such that all myosin heads overlap with actin to permit maximal cross-bridge cycling. Since in this model the actin filaments are usually longer than myosin filaments, the excess length of the actin filament is located randomly with respect to the myosin filament. Once activated, the myosin filament elongates by polymerization along the actin filaments, with the growth limited by the overlap of the actin filaments. During relaxation, the myosin filaments dissociate from the actin filaments, and then the cycle repeats. This process causes a gradual adaptation of force and instantaneous adaptation of shortening velocity. Good agreement is found between model simulations and the experimental data depicting the relationship between force development, myosin filament density, or shortening velocity and length.

scholarly journals Mechanical Properties of the Sarcolemma and Myoplasm in Frog Muscle as a Function of Sarcomere Length

1972 ◽  
Vol 59 (5) ◽  
pp. 559-585 ◽  
Author(s):  
Stanley I. Rapoport
Keyword(s):  
Elastic Modulus ◽  
Fiber Length ◽  
Elastic Moduli ◽  
Sarcomere Length ◽  
Fiber Surface ◽  
Frog Muscle ◽  
Fiber Tension ◽  
Resistance To Deformation ◽  
Longitudinal Elastic Modulus ◽  
Tension Curve

The elastimeter method was applied to the single muscle fiber of the frog semitendinosus to obtain the elastic moduli of the sarcolemma and myoplasm, as well as their relative contributions to resting fiber tension at different extensions. A bleb which was sucked into a flat-mouthed pipette at the fiber surface separated into an external sarcolemmal membrane and a thick inner myoplasmic region. Measurements showed that the sarcolemma does not contribute to intact fiber tension at sarcomere lengths below 3 µ. It was estimated that the sarcolemma contributed on the order of 10% to intact fiber tension at sarcomere lengths between 3 and 3.75 µ, and more so with further extension. Between these sarcomere lengths, the sarcolemma can be linearly extended and has a longitudinal elastic modulus of 5 x 106 dyne/cm2 (assuming a thickness of 0.1 µ). Resistance to deformation of the inner bleb region is due to myoplasmic elasticity. The myoplasmic elastic modulus was estimated by use of a model and was used to predict a fiber length-tension curve which agreed approximately with observations.

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