Contractile properties of single-skinned skeletal muscle fibres of the extensor digitorum longus muscle of the Australian short-nosed echidna

2005 ◽  
Vol 53 (4) ◽  
pp. 237
Author(s):  
Anthony J. Bakker ◽  
Ann L. Parkinson ◽  
Stewart I. Head
Keyword(s):  
Skeletal Muscle ◽  
Extensor Digitorum Longus ◽  
Contractile Properties ◽  
Extensor Digitorum ◽  
Muscle Fibres ◽  
Force Response ◽  
Response Data ◽  
The Mean ◽  
Fast Twitch ◽  
Skeletal Muscle Fibres

Eutherian mammal fast-twitch muscle fibres share similar contractile activation properties, suggesting that these properties are highly conserved in mammals. To investigate this hypothesis, we examined the contractile properties of skeletal muscle from the order Monotremata, a mammalian order that separated from eutherians 150 million years ago. The Ca2+- and Sr2+-activation properties of single mechanically skinned skeletal muscle fibres from the extensor digitorum longus (EDL) muscle of the short-nosed echidna were determined. Sigmoidal curves fitted to force response data plotted as a function of pCa (–log[Ca2+]), had a mean slope of 4.32 ± 0.28 and a mean pCa50 and pCa10 value of 6.18 ± 0.01 and 6.41 ± 0.02 respectively (n = 20). The mean pSr50, pSr10 and slope values of curves fitted to the force-response data after activation with Sr2+ were 4.80 ± 0.03, 5.29 ± 0.07 and 2.75 ± 0.18 respectively (n = 20). The mean pCa50–pSr50 value for the echidna EDL fibres was 1.37 ± 0.04. In five of the echidna fibres, exposure to submaximal Ca2+ concentrations produced myofibrillar force oscillations (mean frequency, 0.13 ± 0.01 Hz), a phenomenon found only in eutherian slow and intermediate muscle fibres. These results show that echidna EDL fibres generally have similar contractile properties to eutherian fast-twitch skeletal muscle fibres, such as those found in the EDL of the rat.

The effect of ionic strength on the kinetics of rigor development in skinned fast-twitch skeletal muscle fibres

1998 ◽  
Vol 435 (6) ◽  
pp. 753-761 ◽  
Author(s):  
C. Veigel ◽  
R. D. von Maydell ◽  
K.R. Kress ◽  
J. E. Molloy ◽  
R. H. A. Fink
Keyword(s):  
Skeletal Muscle ◽  
Ionic Strength ◽  
Muscle Fibres ◽  
Fast Twitch ◽  
Skeletal Muscle Fibres ◽  
Kinetics Of

Myosin light chain phosphorylation-dephosphorylation in mammalian skeletal muscle

1982 ◽  
Vol 242 (3) ◽  
pp. C234-C241 ◽  
Author(s):  
D. R. Manning ◽  
J. T. Stull
Keyword(s):  
Skeletal Muscle ◽  
Light Chain ◽  
Extensor Digitorum Longus ◽  
Myosin Light Chain ◽  
Extensor Digitorum Longus Muscle ◽  
Extensor Digitorum ◽  
Mammalian Skeletal Muscle ◽  
Phosphate Content ◽  
Longus Muscle ◽  
Fast Twitch

Phosphorylation of the myosin light chain 2 (LC2) subunit was examined in rat fast-twitch and slow-twitch skeletal muscles in response to repetitive stimulation at 23 and 35 degrees C and on incubation of fast-twitch skeletal muscle with isoproterenol. After a 1-s tetany at 35 degrees C, LC2 phosphate content in extensor digitorum longus muscle increased rapidly and transiently from 0.21 to 0.51 mol phosphate/mol LC2. This pattern of phosphorylation was similar to that observed at 23 degrees C. Increases in LC2 phosphate content were dependent on the frequency and duration of stimulation. In soleus muscle LC2 phosphate content was minimal following a 1-s tetany but increased markedly following more prolonged tetanies. On incubation of extensor digitorum longus muscle with isoproterenol (20 microM), LC2 phosphate content did not change, whereas phosphorylase a levels increased. A positive correlation existed between LC2 phosphate content and potentiation of peak twitch tension in both types of muscles, suggesting a physiological function for LC2 phosphorylation.

Endothelial cell products alter mammalian skeletal muscle function in vitro

1995 ◽  
Vol 73 (6) ◽  
pp. 736-741 ◽  
Author(s):  
C. L. Murrant ◽  
J. K. Barclay
Keyword(s):  
Skeletal Muscle ◽  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Mammalian Skeletal Muscle ◽  
Skeletal Muscle Function ◽  
Endothelin 1 ◽  
Control Value ◽  
Endothelin 3 ◽  
Fast Twitch

We tested the hypothesis that endothelin and nitric oxide (NO) alter the force developed by fast-twitch and slow-twitch mammalian skeletal muscle, using a mouse skeletal muscle preparation trimmed to approximately 50% of the original diameter to decrease diffusion distances. We suspended trimmed soleus (SOL) and extensor digitorum longus (EDL) muscles in Krebs–Henseleit buffer (27 °C; pH 7.4) gassed with 95% O2 – 5% CO2. Muscles were stimulated once every 90 s for 500 ms at 50 Hz for SOL and 100 Hz for EDL. The force developed by trimmed SOL was 223.8 ± 9.1 mN/mm2 and by EDL was 247.3 ± 9.4 mN/mm2. Endothelin 1 (ET-1) had no effect on EDL but significantly accelerated the rate of decrease of developed force of SOL at concentrations of 10−10 mol/L and higher within 10 contractions. When ET-1 was removed, force returned toward control value. Endothelin 3 (ET-3) had no effect on either muscle. S-Nitroso-N-acetylpenicillamine (SNAP), a source of NO, increased developed force over time in both muscles, with a threshold of 10−6 mol/L. The effect was evident within 5 contractions in both muscles. Force remained elevated above control values after the removal of SNAP. Thus ET-1 attenuated and NO amplified mammalian skeletal muscle function.Key words: soleus, extensor digitorum longus, tetanic contractions, endothelin 1, endothelin 3, S-nitroso-N-acetylpenicillamine.

Myosin isoenzymes in single muscle fibres of Xenopus laevis : analysis of five different functional types

1984 ◽  
Vol 222 (1228) ◽  
pp. 401-408 ◽  
Keyword(s):  
Skeletal Muscle ◽  
Xenopus Laevis ◽  
Muscle Fibres ◽  
Myosin Isoenzymes ◽  
Principal Fibre ◽  
Slow Twitch ◽  
Fast Twitch ◽  
Skeletal Muscle Fibres ◽  
Type 3

An analysis has been performed of the native myosin isoenzyme com position of isolated skeletal muscle fibres from Xenopus laevis with welldefined isotonic contraction properties. Fast twitch ‘ white ’ (type 1) fibres contained three isomyosins; fast twitch ‘red ’ (type 2) fibres showed two major myosin bands with migration velocities very similar to those of the two slower bands in type 1. Slow twitch (type 3) fibres yielded a single, slowly migrating band as did slow tonic (type 5) fibres, whereas the myosin from type 4 (very slow twitch, ‘intermediate’) fibres migrated with a somewhat higher mobility. The results suggest that amphibian skeletal muscle may possess the principal fibre types found in mammals and birds.

scholarly journals When phosphorylated at Thr148, the β2-subunit of AMP-activated kinase does not associate with glycogen in skeletal muscle

2016 ◽  
Vol 311 (1) ◽  
pp. C35-C42 ◽  
Author(s):  
Hongyang Xu ◽  
Noni T. Frankenberg ◽  
Graham D. Lamb ◽  
Paul R. Gooley ◽  
David I. Stapleton ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Carbohydrate Binding ◽  
Binding Function ◽  
Physiological Relevance ◽  
Amp Activated Protein Kinase ◽  
Fast Twitch ◽  
Stimulation Of

The 5′-AMP-activated protein kinase (AMPK), a heterotrimeric complex that functions as an intracellular fuel sensor that affects metabolism, is activated in skeletal muscle in response to exercise and utilization of stored energy. The diffusibility properties of α- and β-AMPK were examined in isolated skeletal muscle fiber segments dissected from rat fast-twitch extensor digitorum longus and oxidative soleus muscles from which the surface membranes were removed by mechanical dissection. After the muscle segments were washed for 1 and 10 min, ∼60% and 75%, respectively, of the total AMPK pools were found in the diffusible fraction. After in vitro stimulation of the muscle, which resulted in an ∼80% decline in maximal force, 20% of the diffusible pool became bound in the fiber. This bound pool was not associated with glycogen, as determined by addition of a wash step containing amylase. Stimulation of extensor digitorum longus muscles resulted in 28% glycogen utilization and a 40% increase in phosphorylation of the downstream AMPK target acetyl carboxylase-CoA. This, however, had no effect on the proportion of total β2-AMPK that was phosphorylated in whole muscle homogenates measured by immunoprecipitation. These findings suggest that, in rat skeletal muscle, β2-AMPK is not associated with glycogen and that activation of AMPK by muscle contraction does not dephosphorylate β2-AMPK. These findings question the physiological relevance of the carbohydrate-binding function of β2-AMPK in skeletal muscle.

Altered myoplasmic Ca2+ handling in rat fast-twitch skeletal muscle fibres during disuse atrophy

2009 ◽  
Vol 459 (4) ◽  
pp. 631-644 ◽  
Author(s):  
Norbert Weiss ◽  
Tina Andrianjafiniony ◽  
Sylvie Dupré-Aucouturier ◽  
Sandrine Pouvreau ◽  
Dominique Desplanches ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibres ◽  
Disuse Atrophy ◽  
Fast Twitch ◽  
Skeletal Muscle Fibres
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