Differential myogenicity of satellite cells isolated from extensor digitorum longus (EDL) and soleus rat muscles revealed in vitro

1998 ◽  
Vol 291 (3) ◽  
pp. 455-468 ◽  
Author(s):  
Catherine Lagord ◽  
Laurent Soulet ◽  
Sylvie Bonavaud ◽  
Yann Bassaglia ◽  
Christiane Rey ◽  
...  
Keyword(s):  
Satellite Cells ◽  
Extensor Digitorum Longus ◽  
Extensor Digitorum

scholarly journals Identification in skeletal muscle of a distinct extracellular pool of amino acids, and its role in protein synthesis

1971 ◽  
Vol 121 (5) ◽  
pp. 817-827 ◽  
Author(s):  
R. C. Hider ◽  
E. B. Fern ◽  
D. R. London
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Incubation Medium ◽  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Longus Muscle ◽  
Kinetics Of

1. The kinetics of radioactive labelling of extra- and intra-cellular amino acid pools and protein of the extensor digitorum longus muscle were studied after incubations with radioactive amino acids in vitro. 2. The results indicated that an extracellular pool could be defined, the contents of which were different from those of the incubation medium. 3. It was concluded that amino acids from the extracellular pool, as defined in this study, were incorporated directly into protein.

Correlation between magnesium and potassium contents in muscle: role of Na(+)-K+ pump

1993 ◽  
Vol 264 (2) ◽  
pp. C457-C463 ◽  
Author(s):  
I. Dorup ◽  
T. Clausen
Keyword(s):  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Deficient Diet ◽  
Young Rats ◽  
Wide Range ◽  
86Rb Influx

In young rats fed a Mg(2+)-deficient diet for 3 wk, Mg2+ and K+ contents in soleus and extensor digitorum longus muscles were significantly reduced and closely correlated. In isolated soleus muscles, Mg2+ depletion induced an even more pronounced loss of K+, and Mg2+ and K+ contents were correlated over a wide range (r = 0.95, P < 0.001). Extracellular Mg2+ (0-1.2 mM) caused no change in total or ouabain-suppressible 86Rb influx. After long-term incubation in Ca(2+)-Mg(2+)-free buffer with EDTA and EGTA, cellular Mg2+ and K+ contents were reduced by 35 and 15%, respectively, without any reduction in ATP and total or ouabain-suppressible 86Rb influx. In Mg(2+)-depleted muscles 42K efflux was increased by up to 42%, and repletion with Mg2+ produced a graded decrease. We conclude that Mg2+ and K+ contents are closely correlated in muscles Mg2+ depleted in vivo or in vitro and that neither extracellular nor moderate intracellular Mg2+ depletion affects total or Na(+)-K+ pump-mediated K+ influx. The reduced K+ content may rather be related to increased K+ efflux from the muscles.

scholarly journals The Effects of Calcium-β-Hydroxy-β-Methylbutyrate on Aging-Associated Apoptotic Signaling and Muscle Mass and Function in Unloaded but Nonatrophied Extensor Digitorum Longus Muscles of Aged Rats

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Brian T. Bennett ◽  
Junaith S. Mohamed ◽  
Stephen E. Alway
Keyword(s):  
Muscle Mass ◽  
Satellite Cells ◽  
Muscle Function ◽  
Extensor Digitorum Longus ◽  
Cross Sectional Area ◽  
Extensor Digitorum ◽  
Aged Rats ◽  
Sectional Area ◽  
Cross Sectional ◽  
Apoptotic Signaling

Beta-hydroxy-beta-methylbutyrate (HMB), a naturally occurring leucine metabolite, has been shown to attenuate plantar flexor muscle loss and increase myogenic stem cell activation during reloading after a period of significant muscle wasting by disuse in old rodents. However, it was less clear if HMB would alter dorsiflexor muscle response to unloading or reloading when there was no significant atrophy that was induced by unloading. In this study, we tested if calcium HMB (Ca-HMB) would improve muscle function and alter apoptotic signaling in the extensor digitorum longus (EDL) of aged animals that were unloaded but did not undergo atrophy. The EDL muscle was unloaded for 14 days by hindlimb suspension (HS) in aged (34-36 mo.) male Fisher 344×Brown Norway rats. The rats were removed from HS and allowed normal cage ambulation for 14 days of reloading (R). Throughout the study, the rats were gavaged daily with 170 mg of Ca-HMB or water 7 days prior to HS, then throughout 14 days of HS and 14 days of recovery after removing HS. The animals’ body weights were significantly reduced by ~18% after 14 days of HS and continued to decline by ~22% during R as compared to control conditions; however, despite unloading, EDL did not atrophy by HS, nor did it increase in mass after R. No changes were observed in EDL twitch contraction time, force production, fatigue resistance, fiber cross-sectional area, or markers of nuclear apoptosis (myonuclei + satellite cells) after HS or R. While HS and R increased the proapoptotic Bax protein abundance, BCL-2 abundance was also increased as was the frequency of TUNEL-positive myonuclei and satellite cells, yet muscle mass and fiber cross-sectional area did not change and Ca-HMB treatment had no effect reducing apoptotic signaling. These data indicate that (i) increased apoptotic signaling preceded muscle atrophy or occurred without significant EDL atrophy and (ii) that Ca-HMB treatment did not improve EDL signaling, muscle mass, or muscle function in aged rats, when HS and R did not impact mass or function.

scholarly journals The influence of passive stretch on the growth and protein turnover of the denervated extensor digitorum longus muscle

1978 ◽  
Vol 174 (2) ◽  
pp. 595-602 ◽  
Author(s):  
David F. Goldspink
Keyword(s):  
Protein Synthesis ◽  
Extensor Digitorum Longus ◽  
Similar Rate ◽  
Extensor Digitorum Longus Muscle ◽  
Extensor Digitorum ◽  
Denervated Muscle ◽  
Longus Muscle ◽  
Induced Changes ◽  
Passive Stretch

At 7 days after cutting the sciatic nerve, the extensor digitorum longus muscle was smaller and contained less protein than its innervated control. Correlating with these changes was the finding of elevated rates of protein degradation (measured in vitro) in the denervated tissue. However, at this time, rates of protein synthesis (measured in vitro) and nucleic acid concentrations were also higher in the denervated tissue, changes more usually associated with an active muscle rather than a disused one. These anabolic trends have, at least in part, been explained by the possible greater exposure of the denervated extensor digitorum longus to passive stretch. When immobilized under a maintained influence of stretch the denervated muscle grew to a greater extent. Although this stretch-induced growth appeared to occur predominantly through a stimulation of protein synthesis, it was opposed by smaller increases in degradative rates. Nucleic acids increased at a similar rate to the increase in muscle mass when a continuous influence of stretch was imposed on the denervated tissue. In contrast, immobilization of the denervated extensor digitorum longus in a shortened unstretched state reversed most of the stretch-induced changes; that is, the muscle became even smaller, with protein synthesis decreasing to a greater extent than breakdown after the removal of passive stretch. The present investigation suggests that stretch will promote protein synthesis and hence growth of the extensor digitorum longus even in the absence of an intact nerve supply. However, some factor(s), in addition to passive stretch, must contribute to the anabolic trends in this denervated muscle.

scholarly journals The effect of tendon compliance on in vitro/in vivo estimations of sarcomere length

1995 ◽  
Vol 198 (2) ◽  
pp. 503-506
Author(s):  
R James ◽  
I Young ◽  
J Altringham
Keyword(s):  
Extensor Digitorum Longus ◽  
Sarcomere Length ◽  
Extensor Digitorum Longus Muscle ◽  
Extensor Digitorum ◽  
Worst Case ◽  
Longus Muscle ◽  
Tendon Compliance

The errors likely to result from using excised rigor muscles to determine in vivo sarcomere length ranges were calculated for mouse extensor digitorum longus muscle (EDL). This muscle was chosen because its very long tendon makes it particularly susceptible to errors arising from tendon compliance. By placing dissected limbs into different locomotory stances, and allowing them to go into rigor, the range of sarcomere lengths over which muscles operate in vivo can be determined, but it is subject to errors due to tendon compliance. A tendon compliance of 0.24 GPa and a muscle rigor stress of 35 kPa were determined, and these were used to correct the estimates of in vivo sarcomere length, under worst case conditions. The error introduced was very small: a reduction in sarcomere length of less than 0.5 %.

Alterations in intramuscular connective tissue after limb casting affect contraction-induced muscle injury

1995 ◽  
Vol 78 (3) ◽  
pp. 1065-1069 ◽  
Author(s):  
T. K. Lapier ◽  
H. W. Burton ◽  
R. Almon ◽  
F. Cerny
Keyword(s):  
Connective Tissue ◽  
Muscle Injury ◽  
Extensor Digitorum Longus ◽  
Plantar Flexion ◽  
Extensor Digitorum ◽  
Control Group ◽  
Longus Muscle ◽  
Limb Immobilization

This study examined the effect of alterations in rat intramuscular connective tissue (CT), secondary to limb immobilization, on the muscle's susceptibility to contraction-induced injury. Hindlimbs were casted for 3 wk with the extensor digitorum longus muscle fixed in a shortened (IM-SP) or lengthened position (IM-LP). An age-matched control group remained uncasted. Extensor digitorum longus muscles were injured in vivo by using a motorized foot pedal that repeatedly flexed and extended the foot while the muscle was electrically stimulated during plantar flexion. Four hours postinjury, maximum isometric tetanic force (Po) was measured in vitro and was used as a functional index of muscle injury. Muscles were fixed, sectioned, and stained for later analysis. Intramuscular CT concentration, expressed as the ratio of CT area to muscle fiber area, was significantly higher in both IM-SP (0.153 +/- 0.003) and IM-LP (0.174 +/- 0.003) groups compared with controls (0.104 +/- 0.003). Po values of injured muscles both IM-LP and IM-SP were higher than the injured controls' Po of 9.41 +/- 0.63 N/cm2 (P < 0.05). Injured IM-LP muscle forces were significantly higher than those of IM-SP. This study demonstrated that limb immobilization increases intramuscular CT concentration, which is accompanied by attenuation of muscle injury. We conclude that remodeling of intramuscular CT affects the muscle's resistance to contraction-induced injury.

scholarly journals Regulation of total and myofibrillar protein breakdown in rat extensor digitorum longus and soleus muscle incubated flaccid or at resting length

1990 ◽  
Vol 267 (1) ◽  
pp. 37-44 ◽  
Author(s):  
P O Hasselgren ◽  
M Hall-Angerås ◽  
U Angerås ◽  
D Benson ◽  
J H James ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Total Protein ◽  
Extensor Digitorum Longus ◽  
Myofibrillar Protein ◽  
Extensor Digitorum ◽  
Protein Breakdown ◽  
Breakdown Rate ◽  
Net Production ◽  
Breakdown Rates

The present study characterized total and myofibrillar protein breakdown rates in a muscle preparation frequently used in vitro, i.e. incubated extensor digitorum longus (EDL) and soleus (SOL) muscles of young rats. Total and myofibrillar protein breakdown rates were assessed by determining net production by the incubated muscles of tyrosine and 3-methylhistidine (3-MH) respectively. Both amino acids were determined by h.p.l.c. Both total and myofibrillar protein breakdown rates were higher in SOL than in EDL muscles and were decreased by incubating the muscles maintained at resting length, rather than flaccid. After fasting for 72 h, total protein breakdown (i.e. tyrosine release) was increased by 73% and 138% in EDL muscles incubated flaccid and at resting length respectively. Net production of tyrosine by SOL muscle was not significantly altered by fasting. In contrast, myofibrillar protein degradation (i.e. 3-MH release) was markedly increased by fasting in both muscles. When tissue was incubated in the presence of 1 munit of insulin/ml, total protein breakdown rate was inhibited by 17-20%, and the response to the hormone was similar in muscles incubated flaccid or at resting length. In contrast, myofibrillar protein breakdown rate was not altered by insulin in any of the muscle preparations. The results support the concepts of individual regulation of myofibrillar and non-myofibrillar proteins and of different effects of various conditions on protein breakdown in different types of skeletal muscle. Thus determination of both tyrosine and 3-MH production in red and white muscle is important for a more complete understanding of protein regulation in skeletal muscle.

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