scholarly journals Different sensitivity of miniature endplate currents in rat external and internal intercostal muscles to the acetylcholinesterase inhibitor C-547 as compared with diaphragm and extensor digitorum longus

2009 ◽  
pp. 149-153
Author(s):  
K Petrov ◽  
I Kovyazina ◽  
V Zobov ◽  
E Bukharaeva ◽  
EE Nikolsky ◽  
...  
Keyword(s):  
Cholinesterase Inhibitor ◽  
Extensor Digitorum Longus ◽  
Acetylcholinesterase Inhibitor ◽  
Extensor Digitorum ◽  
Experimental Animals ◽  
Intercostal Muscles ◽  
Limb Muscles ◽  
Exercise Induced ◽  
28 Nm

Derivative of 6-methyluracil, selective cholinesterase inhibitor C547 potentiates miniature endplate currents (MEPCs) in rat external intercostal muscles (external ICM) more effectively than in internal intercostal muscles (internal ICM). Effect of the C-547 on intercostal muscles was compared with those on extensor digitorum longus (EDL) and diaphragm muscles. Half-effective concentrations for τ of MEPC decay arranged in increasing order were as follows: EDL, locomotor muscle, most sensitive = 1.3 nM, external ICM, inspiration muscle = 6.8 nM, diaphragm, main inspiration muscle = 28 nM, internal ICM, expiration muscle = 71 nM. External ICM might therefore be inhibited, similarly as the limb muscles, by nanomolar concentrations of the drug and do not participate in inspiration in the presence of the C-547. Moreover, internal ICM inhibition can hinder the expiration during exercise-induced fast breathing of C-547- treated experimental animals.

Changes in muscle activity with exercise-induced fatigue in Thoroughbred horses

2020 ◽  
pp. 1-10
Author(s):  
Y. Takahashi ◽  
K. Mukai ◽  
H. Ohmura ◽  
T. Takahashi
Keyword(s):  
Muscle Activity ◽  
Extensor Digitorum Longus ◽  
Gluteus Medius ◽  
Extensor Digitorum ◽  
Stride Frequency ◽  
Median Frequency ◽  
Propulsive Force ◽  
Triceps Brachii ◽  
Frequency Changes ◽  
Exercise Induced

Understanding the effects of fatigue can provide guidance for training regimens and injury prevention. We have previously reported that the integrated-electromyogram (iEMG) values of the M. gluteus medius and brachiocephalicus decreased with exercise-induced fatigue, whereas those of the M. longissimus dorsi and infraspinatus were not affected. We hypothesised that exercise-induced fatigue would decrease the activities of the muscles associated with propulsive force but not associated with joint stabilisation. Surface EMG recordings of the forelimb muscles (M. triceps brachii, common digital extensor, ulnaris lateralis), and hindlimb muscles (M. semitendinosus, extensor digitorum longus, extensor digitorum lateralis and flexor digitorum lateralis) were conducted on eight Thoroughbreds. Horses galloped on a treadmill (grade, 3%) at a constant speed (12.6-14.8 m/s) until they could not maintain their position with minimal human encouragement (~5 min). The stride frequency, iEMG for a stride and median frequency during muscle discharge were calculated every 30 s. These parameters were compared between the start and end of the test phase for the leading and trailing limbs. The stride frequency (P<0.01) and iEMG values of the M. semitendinosus in both the leading (P<0.01) and trailing limbs (P<0.05) and those of the M. extensor digitorum longus in the trailing limbs (P<0.05) significantly decreased at the end of the test. No median frequency changes were observed in the assessed muscles. Although muscular fatigue itself was not detected, observed fatigue caused by high-intensity exercise resulted in inability to maintain speed, which was associated with decreased iEMG values in the hip extensor muscles that generate propulsive force. In contrast, almost all muscles that stabilise joints were unaffected by fatigue. One exception was the decreased muscle activity observed in the M. extensor digitorum longus of the trailing limb, which may suggest unstable ground contact. Muscle activity changes with fatigue might be associated with muscle functions.

scholarly journals Myostatin dysfunction impairs force generation in extensor digitorum longus muscle and increases exercise-induced protein efflux from extensor digitorum longus and soleus muscles

2015 ◽  
Vol 40 (8) ◽  
pp. 817-821 ◽  
Author(s):  
Juozas Baltusnikas ◽  
Audrius Kilikevicius ◽  
Tomas Venckunas ◽  
Andrej Fokin ◽  
Lutz Bünger ◽  
...  
Keyword(s):  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Muscle Size ◽  
Wild Type ◽  
Protein Loss ◽  
Muscle Properties ◽  
Longus Muscle ◽  
Generating Capacity ◽  
Contraction Times ◽  
Exercise Induced

Myostatin dysfunction promotes muscle hypertrophy, which can complicate assessment of muscle properties. We examined force generating capacity and creatine kinase (CK) efflux from skeletal muscles of young mice before they reach adult body and muscle size. Isolated soleus (SOL) and extensor digitorum longus (EDL) muscles of Berlin high (BEH) mice with dysfunctional myostatin, i.e., homozygous for inactivating myostatin mutation, and with a wild-type myostatin (BEH+/+) were studied. The muscles of BEH mice showed faster (P < 0.01) twitch and tetanus contraction times compared with BEH+/+ mice, but only EDL displayed lower (P < 0.05) specific force. SOL and EDL of age-matched but not younger BEH mice showed greater exercise-induced CK efflux compared with BEH+/+ mice. In summary, myostatin dysfunction leads to impairment in muscle force generating capacity in EDL and increases susceptibility of SOL and EDL to protein loss after exercise.

The effect of a growth promoting drug, clenbuterol, on fibre frequency and area in hind limb muscles from young male rats

1986 ◽  
Vol 6 (3) ◽  
pp. 293-299 ◽  
Author(s):  
C. A. Maltin ◽  
M. I. Delday ◽  
P. J. Reeds
Keyword(s):  
Hind Limb ◽  
Extensor Digitorum Longus ◽  
Young Male ◽  
Extensor Digitorum ◽  
Male Rats ◽  
Cross Sectional ◽  
Limb Muscles ◽  
Fibre Number ◽  
Wet Weight ◽  
Growth Promoting

The effect of dietary administration of clenbuterol on soleus and extensor digitorum longus muscles was studied after 4 and 21 days. Both muscles showed an increase in wet weight with no significant change in total fibre number. After 4 days fibre cross-sectional areas were increased in soleus, but not in extensor digitorum longus, and after 21 days there was a change in fibre frequencies in extensor digitorum longus but not soleus muscles.

Exercise-induced alterations in skeletal muscle myosin heavy chain phenotype: dose-response relationship

1999 ◽  
Vol 86 (3) ◽  
pp. 1002-1008 ◽  
Author(s):  
Haydar A. Demirel ◽  
Scott K. Powers ◽  
Hisashi Naito ◽  
Michael Hughes ◽  
Jeff S. Coombes
Keyword(s):  
Exercise Training ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Extensor Digitorum Longus ◽  
Citrate Synthase ◽  
Extensor Digitorum ◽  
Control Group ◽  
Sprague Dawley ◽  
Skeletal Muscle Myosin ◽  
Exercise Induced

This study investigated the effects of exercise training duration on the myosin heavy chain (MHC) isoform distribution in rat locomotor muscles. Female Sprague-Dawley rats (120 days old) were assigned to either a sedentary control group or to one of three endurance exercise training groups. Trained animals ran on a treadmill at ∼75% maximal O2 uptake for 10 wk (4–5 days/wk) at one of three different exercise durations (30, 60, or 90 min/day). Training resulted in increases ( P < 0.05) in citrate synthase activity in the soleus and extensor digitorum longus in both the 60 and 90 min/day duration groups and in the plantaris (Pla) in all three exercise groups. All durations of training resulted in a reduction ( P < 0.05) in the percentage of MHCIIb and an increase ( P < 0.05) in the percentage of MHCIIa in the Pla. The magnitude of change in the percentage of MHCIIb in the Pla increased as a function of the training duration. In the extensor digitorum longus, 90 min of daily exercise promoted a decrease ( P < 0.05) in percentage of MHCIIb and increases ( P < 0.05) in the percentages of MHCI, MHCIIa, and MHCIId/x. Finally, training durations ≥60 min resulted in an increase ( P < 0.05) in the percentage of MHCI and a concomitant decrease ( P < 0.05) in the percentage of MHCIIa in the soleus. These results demonstrate that increasing the training duration elevates the magnitude of the fast-to-slow shift in MHC phenotype in rat hindlimb muscles.

Human growth hormone treatment of hypophysectomized rats increases the proportion of type-1 fibres in skeletal muscle

1989 ◽  
Vol 123 (3) ◽  
pp. 429-NP ◽  
Author(s):  
C. M. Ayling ◽  
B. H. Moreland ◽  
J. M. Zanelli ◽  
D. Schulster
Keyword(s):  
Skeletal Muscle ◽  
Fibre Type ◽  
Extensor Digitorum Longus ◽  
Human Growth ◽  
Hormone Treatment ◽  
Pituitary Hormones ◽  
Extensor Digitorum ◽  
Replacement Treatment ◽  
Hypophysectomized Rats

ABSTRACT The studies describe alterations after hypophysectomy in the proportion of the type-1 and type-2 fibres in rat skeletal muscles, and the effects of replacement treatment with pituitary human (h) GH. Cytochemical analysis of myosin ATPase, succinate dehydrogenase and lactate dehydrogenase activities in sections of rat hind limb muscles were used as markers of fibre type and revealed that hypophysectomy reduced the proportion of type-1 fibres by 50% in soleus and in extensor digitorum longus muscles. This reduction in the proportion of type-1 fibres was accompanied by the appearance of transitional fibres (type 2C/1B). Following seven daily injections of hGH (60 mIU/day) to hypophysectomized rats, the proportion of type-1 fibres in both soleus and in extensor digitorum longus was increased with a concomitant reduction in the number of transitional fibres. After 11 days of treatment, all these transitional fibres had reverted back to type-1 fibres. Only hGH was observed to elicit this effect; injections of other pituitary hormones had no effect on the proportions of these transitional fibres. These alterations in fibre type occurred more rapidly than the changes reported after prolonged electrical stimulation of muscle or following extended exercise. These findings suggest that hypophysectomy and GH injection can result in a rapid alteration in the fibre composition of skeletal muscle, which may have important implications in terms of the resistance to fatigue and speed of contraction of the muscle. Journal of Endocrinology (1989) 123, 429–435

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.

Relationships between muscle membrane lipids, fiber type, and enzyme activities in sedentary and exercised rats

1995 ◽  
Vol 269 (5) ◽  
pp. R1154-R1162 ◽  
Author(s):  
A. D. Kriketos ◽  
D. A. Pan ◽  
J. R. Sutton ◽  
J. F. Hoh ◽  
L. A. Baur ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Extensor Digitorum Longus ◽  
Unsaturated Fatty Acids ◽  
Citrate Synthase ◽  
Fiber Type ◽  
Saturated Fatty Acids ◽  
Extensor Digitorum ◽  
Female Rats ◽  
Muscle Membrane

Insulin resistance in skeletal muscle is associated with 1) relative increases in the proportion of glycolytic and fast-twitch muscle fibers and decreases in the proportion of more oxidative fibers and 2) a higher proportion of the saturated fatty acids in membrane structural lipids. Exercise is known to improve insulin action. The aims of the current studies were 1) to investigate the relationship between muscle fiber type and membrane fatty acid composition and 2) to determine how voluntary exercise might influence both variables. In sedentary Wistar rats in experiment 1, increased amounts of unsaturated fatty acids were found in the more oxidative insulin-sensitive red quadriceps and soleus muscles, whereas reduced levels of polyunsaturated fatty acids were found in primarily glycolytic white quadriceps muscles. In experiment 2, voluntary running-wheel exercise by adult female rats over 45 days resulted in reduced proportions of type IIb fibers (P = 0.01) and increased proportions of type IIa/IIx fibers (P = 0.03) in extensor digitorum longus muscle. The magnitude of these changes was related to the distance run (r = -0.73, P = 0.04; r = 0.79, P = 0.02, respectively). Exercise significantly increased oxidative capacity, as assessed by the proportion of intensely NADH-stained fibers (P = 0.0004) and citrate synthase (P = 0.003) and hexokinase (P = 0.04) activities. Citrate synthase activity was also increased by exercise in soleus muscle, where, as expected, no fiber type changes were detected. No significant differences in the fatty acid profile of soleus and extensor digitorum longus were found between groups.(ABSTRACT TRUNCATED AT 250 WORDS)

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