scholarly journals Variation in normalized isometric tetanic force of isolated fast-twitch muscle fibres of Rana temporaria.

1997 ◽  
Vol 200 (3) ◽  
pp. 523-529
Author(s):  
H P Buschman ◽  
W J van der Laarse ◽  
G J Stienen ◽  
G Elzinga
Keyword(s):  
Total Variation ◽  
Rana Temporaria ◽  
Unit Length ◽  
Force Production ◽  
Rest Period ◽  
Muscle Fibres ◽  
Sectional Area ◽  
Cross Sectional ◽  
Tetanic Force ◽  
Fast Twitch

The origin of the threefold variation found previously in isometric force normalized to cross-sectional area of single fast-twitch tibialis anterior muscle fibres of the frog Rana temporaria was studied by using (1) a strictly defined stimulus protocol, and (2) influencing the condition of the frog using artificial hibernation. Variation in normalized force was found to be influenced by the length of the rest period between tetani. After a long rest (> 6h), tetanic force production was less than for a tetanus produced after 1 h. The length of the rest period accounted for a factor of 1.24 of the total variation in normalized force. The condition of the frog also influenced normalized force production. Little variation in normalized force was observed between different fibres from the same animal, whereas a significant difference was found between animals. After artificial hibernation, force normalized to cross-sectional area remained unchanged, but force normalized to dry mass per unit length increased; the total variation increased from a factor of 1.37 to a factor of 1.64. Force normalized to muscle protein mass per unit length, however, was not affected by artificial hibernation. We conclude that variation in normalized tetanic force can be partly reduced by standardization of the stimulation protocol and normalization to protein content per unit length.

scholarly journals Neuromuscular organization of avian flight muscle: architecture of single muscle fibres in muscle units of the pectoralis (pars thoracicus) of pigeon (Columba livia)

1999 ◽  
Vol 354 (1385) ◽  
pp. 917-925 ◽  
Author(s):  
A. J. Sokoloff ◽  
G. E. Goslow
Keyword(s):  
Motor Unit ◽  
Cross Sections ◽  
Unit Length ◽  
Muscle Length ◽  
Motor Units ◽  
Columba Livia ◽  
Muscle Fibres ◽  
Cross Sectional ◽  
Total Length ◽  
Fast Twitch

The M. pectoralis (pars thoracicus) of pigeons ( Columba livia ) is comprised of short muscle fibres that do not extend from muscle origin to insertion but overlap ‘in-series’. Individual pectoralis motor units are limited in territory to a portion of muscle length and are comprised of either fast twitch, oxidative and glycolytic fibres (FOG) or fast twitch and glycolytic fibres (FG). FOG fibres make up 88 to 90% of the total muscle population and have a mean diameter one-half of that of the relatively large FG fibres. Here we report on the organization of individual fibres identified in six muscle units depleted of glycogen, three comprised of FOG fibres and three comprised of FG fibres. For each motor unit, fibre counts revealed unequal numbers of depleted fibres in different unit cross-sections. We traced individual fibres in one unit comprised of FOG fibres and a second comprised of FG fibres. Six fibres from a FOG unit (total length 15.45 mm) ranged from 10.11 to 11.82 mm in length and averaged (±s.d.) 10.74±0.79 mm. All originated bluntly (en mass) from a fascicle near the proximal end of the muscle unit and all terminated intramuscularly. Five of these ended in a taper and one ended bluntly. Fibres coursed on average for 70% of the muscle unit length. Six fibres from a FG unit (total length 34.76 mm) ranged from 8.97 to 18.38 mm in length and averaged 15.32 ±3.75 mm. All originated bluntly and terminated intramuscularly; one of these ended in a taper and five ended bluntly. Fibres coursed on average for 44% of the muscle unit length. Because fibres of individual muscle units do not extend the whole muscle unit territory, the effective cross-sectional area changes along the motor unit length. These non-uniformities in the distribution of fibres within a muscle unit emphasize that the functional interactions within and between motor units are complex.

Form follows function: how muscle shape is regulated by work

2000 ◽  
Vol 88 (3) ◽  
pp. 1127-1132 ◽  
Author(s):  
Brenda Russell ◽  
Delara Motlagh ◽  
William W. Ashley
Keyword(s):  
Muscle Cell ◽  
Cell Shape ◽  
Force Production ◽  
Cardiac Cells ◽  
Cross Sectional Area ◽  
Dynamic Responses ◽  
Mechanical Activity ◽  
Sectional Area ◽  
Cross Sectional ◽  
A Cell

What determines the shape, size, and force output of cardiac and skeletal muscle? Chicago architect Louis Sullivan (1856–1924), father of the skyscraper, observed that “form follows function.” This is as true for the structural elements of a striated muscle cell as it is for the architectural features of a building. Function is a critical evolutionary determinant, not form. To survive, the animal has evolved muscles with the capacity for dynamic responses to altered functional demand. For example, work against an increased load leads to increased mass and cross-sectional area (hypertrophy), which is directly proportional to an increased potential for force production. Thus a cell has the capacity to alter its shape as well as its volume in response to a need for altered force production. Muscle function relies primarily on an organized assembly of contractile and other sarcomeric proteins. From analysis of homogenized cells and molecular and biochemical assays, we have learned about transcription, translation, and posttranslational processes that underlie protein synthesis but still have done little in addressing the important questions of shape or regional cell growth. Skeletal muscles only grow in length as the bones grow; therefore, most studies of adult hypertrophy really only involve increased cross-sectional area. The heart chamber, however, can extend in both longitudinal and transverse directions, and cardiac cells can grow in length and width. We know little about the regulation of these directional processes that appear as a cell gets larger with hypertrophy or smaller with atrophy. This review gives a brief overview of the regulation of cell shape and the composition and aggregation of contractile proteins into filaments, the sarcomere, and myofibrils. We examine how mechanical activity regulates the turnover and exchange of contraction proteins. Finally, we suggest what kinds of experiments are needed to answer these fundamental questions about the regulation of muscle cell shape.

Observations on the number of nuclei within the fibres of some red and white muscles

1977 ◽  
Vol 23 (1) ◽  
pp. 269-284 ◽  
Author(s):  
I.G. Burleigh
Keyword(s):  
Cross Sectional Area ◽  
Growth Potential ◽  
Muscle Fibres ◽  
Sectional Area ◽  
Adult Rats ◽  
Cross Sectional ◽  
Physiological Properties ◽  
Phasic Type ◽  
The One ◽  
Red And White Muscles

Nuclei have been enumerated in muscle fibres of different physiological properties within adult rats and rabbits. Almost invariably, and regardless of muscle type, there is a direct relationship between the cross-sectional area (or fibre breadth) of muscle fibres and the number of nuclei within them. The one exception occurred in muscles of older rats where increased nuclear numbers do not always appear to result in broader muscle fibres. The greater complement of nuclei in broader fibres is accompanied by larger amounts of cell substance per nucleus. Confirming early observations in the literature, red fibres of the slow-phasic type have more nuclei than have white, fast-phasic fibres of similar breadth. These conclusions are not vitiated by differences in the number of nuclei within capillaries or in satellite cells, by differences in nuclear length or by variation in the degree to which fibres are contracted. In respect of their complement of nuclei, and the average amount of cell substance formed per nucleus the small red fibres that occur within muscles of predominantly fast-phasic character appear to be fast-rather than slow-phasic in type. When the number of nuclei observed per fibre is plotted against fibre cross-sectional area, the shapes of the resulting distributions suggest that estimates of muscle nuclei may be valuable not only as an index of growth potential, but of the extent to which that potential is expressed. In one muscle, the above distribution was of a form which indicated that some fibres may have formed abnormally large amounts of protein per nucleus. However, this was not adequately confirmed. Various factors have been investigated that are relevant to the accuracy of enumerating nuclei and measuring fibre breadths.

Shift from slow- to fast-twitch muscle fibres in skeletal muscle of newborn heterozygous and homozygous myostatin-knockout piglets

2019 ◽  
Vol 31 (10) ◽  
pp. 1628 ◽  
Author(s):  
Mei-Fu Xuan ◽  
Zhao-Bo Luo ◽  
Jun-Xia Wang ◽  
Qing Guo ◽  
Sheng-Zhong Han ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Expression ◽  
Muscle Development ◽  
Transforming Growth Factor ◽  
Myogenic Differentiation ◽  
Muscle Fibres ◽  
Skeletal Muscle Development ◽  
Cross Sectional ◽  
Gene And Protein Expression ◽  
Fast Twitch

Myostatin (MSTN) is a member of the transforming growth factor-β superfamily that negatively regulates skeletal muscle development. A lack of MSTN induces muscle hypertrophy and increases formation of fast-twitch (Type II) muscle fibres. This study investigated muscle development in newborn heterozygous (MSTN+/−) and homozygous (MSTN−/−) MSTN-knockout piglets. Detailed morphological and gene and protein expression analyses were performed of the biceps femoris, semitendinosus and diaphragm of MSTN+/−, MSTN−/− and wild-type (WT) piglets. Haematoxylin–eosin staining revealed that the cross-sectional area of muscle fibres was significantly larger in MSTN-knockout than WT piglets. ATPase staining demonstrated that the percentage of Type IIb and IIa muscle fibres was significantly higher in MSTN−/− and MSTN+/− piglets respectively than in WT piglets. Western blotting showed that protein expression of myosin heavy chain-I was reduced in muscles of MSTN-knockout piglets. Quantitative reverse transcription–polymerase chain reaction revealed that, compared with WT piglets, myogenic differentiation factor (MyoD) mRNA expression in muscles was 1.3- to 2-fold higher in MSTN+/− piglets and 1.8- to 3.5-fold higher MSTN−/− piglets (P<0.05 and P<0.01 respectively). However, expression of myocyte enhancer factor 2C (MEF2C) mRNA in muscles was significantly lower in MSTN+/− than WT piglets (P<0.05). MSTN plays an important role in skeletal muscle development and regulates muscle fibre type by modulating the gene expression of MyoD and MEF2C in newborn piglets.

scholarly journals Variable maternal nutrition and growth hormone treatment in the second quarter of pregnancy in pigs alter semitendinosus muscle in adolescent progeny

2003 ◽  
Vol 90 (2) ◽  
pp. 283-293 ◽  
Author(s):  
Kathryn L. Gatford ◽  
Jason E. Ekert ◽  
Karina Blackmore ◽  
Miles J. De Blasio ◽  
Jodie M. Boyce ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Maternal Nutrition ◽  
Maternal Plasma ◽  
Cross Sectional Area ◽  
Muscle Fibres ◽  
Sectional Area ◽  
Large White ◽  
Semitendinosus Muscle ◽  
Gh Treatment ◽  
Cross Sectional

Maternal nutrition and growth hormone (GH) treatment during early- to mid-pregnancy can each alter the subsequent growth and differentiation of muscle in progeny. We have investigated the effects of varying maternal nutrition and maternal treatment with porcine (p) GH during the second quarter of pregnancy in gilts on semitendinosus muscle cross-sectional area and fibre composition of progeny, and relationships between maternal and progeny measures and progeny muscularity. Fifty-three Large White×Landrace gilts, pregnant to Large White×Duroc boars, were fed either 2·2 kg (about 35 % ad libitum intake) or 3·0 kg commercial ration (13·5 MJ digestible energy, 150 g crude protein (N×6·25)/kg DM)/d and injected with 0, 4 or 8 mg pGH/d from day 25 to 50 of pregnancy, then all were fed 2·2 kg/d for the remainder of pregnancy. The higher maternal feed allowance from day 25 to 50 of pregnancy increased the densities of total and secondary fibres and the secondary:primary fibre ratio in semitendinosus muscles of their female progeny at 61 d of age postnatally. The densities of secondary and total muscle fibres in semitendinosus muscles of progeny were predicted by maternal weight before treatment and maternal plasma insulin-like growth factor-II during treatment. Maternal pGH treatment from day 25 to day 50 of pregnancy did not alter fibre densities, but increased the cross-sectional area of the semitendinosus muscle; this may be partially explained by increased maternal plasma glucose. Thus, maternal nutrition and pGH treatment during the second quarter of pregnancy in pigs independently alter muscle characteristics in progeny.

Fibre types in breast and leg muscles of hand-reared and wild grey partridge (Perdix perdix)

1998 ◽  
Vol 76 (2) ◽  
pp. 236-242 ◽  
Author(s):  
Ahti EI Pyörnilä ◽  
Ahti P Putaala ◽  
Raimo K Hissa
Keyword(s):  
Relative Number ◽  
Fibre Types ◽  
Muscle Fibres ◽  
Poor Survival ◽  
Cross Sectional ◽  
Perdix Perdix ◽  
Grey Partridge ◽  
The Poor ◽  
In The Wild ◽  
Fast Twitch

Fibre types and sizes and their relative numbers and cross-sectional areas in M. pectoralis, M. supracoracoideus, and M. iliotibialis of hand-reared and wild grey partridge (Perdix perdix) were determined in order to see if there are differences that could account for the poor survival of hand-reared birds released into the wild. Histochemical staining for myosin ATPase and succinate dehydrogenase (SDH) showed that most breast-muscle fibres (80-90%) are of the fast-twitch glycolytic (FG) type and a smaller portion of the fast-twitch oxidative glycolytic (FOG) type. In M. iliotibialis, about 60% of the fibres were FG fibres and the rest were of the FOG type. Judging from the low intensity of SDH staining, FOG fibres in the grey partridge appear weakly oxidative only. The relative number of FG fibres and their relative cross-sectional area in M. pectoralis were larger in the hand-reared than in the wild birds. The cross-sectional areas of both fibre types in M. iliotibialis were significantly larger in the hand-reared birds. Taken as a whole, these findings alone do not account for the poor survival of hand-reared partridge in the wild.

scholarly journals Role of TRPC1 channel in skeletal muscle function

2010 ◽  
Vol 298 (1) ◽  
pp. C149-C162 ◽  
Author(s):  
Nadège Zanou ◽  
Georges Shapovalov ◽  
Magali Louis ◽  
Nicolas Tajeddine ◽  
Chiara Gallo ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Function ◽  
Transient Receptor Potential ◽  
Force Production ◽  
Receptor Potential ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Skeletal Muscle Function ◽  
Cross Sectional

Skeletal muscle contraction is reputed not to depend on extracellular Ca2+. Indeed, stricto sensu , excitation-contraction coupling does not necessitate entry of Ca2+. However, we previously observed that, during sustained activity (repeated contractions), entry of Ca2+is needed to maintain force production. In the present study, we evaluated the possible involvement of the canonical transient receptor potential (TRPC)1 ion channel in this entry of Ca2+and investigated its possible role in muscle function. Patch-clamp experiments reveal the presence of a small-conductance channel (13 pS) that is completely lost in adult fibers from TRPC1−/−mice. The influx of Ca2+through TRPC1 channels represents a minor part of the entry of Ca2+into muscle fibers at rest, and the activity of the channel is not store dependent. The lack of TRPC1 does not affect intracellular Ca2+concentration ([Ca2+]i) transients reached during a single isometric contraction. However, the involvement of TRPC1-related Ca2+entry is clearly emphasized in muscle fatigue. Indeed, muscles from TRPC1−/−mice stimulated repeatedly progressively display lower [Ca2+]itransients than those observed in TRPC1+/+fibers, and they also present an accentuated progressive loss of force. Interestingly, muscles from TRPC1−/−mice display a smaller fiber cross-sectional area, generate less force per cross-sectional area, and contain less myofibrillar proteins than their controls. They do not present other signs of myopathy. In agreement with in vitro experiments, TRPC1−/−mice present an important decrease of endurance of physical activity. We conclude that TRPC1 ion channels modulate the entry of Ca2+during repeated contractions and help muscles to maintain their force during sustained repeated contractions.

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