scholarly journals Effects of re-feeding after prolonged starvation on pyruvate dehydrogenase activities in heart, diaphragm and selected skeletal muscles of the rat

1989 ◽  
Vol 262 (2) ◽  
pp. 669-672 ◽  
Author(s):  
M C Sugden ◽  
M J Holness
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Dehydrogenase ◽  
Tibialis Anterior ◽  
Skeletal Muscles ◽  
Extensor Digitorum Longus ◽  
Glycogen Synthesis ◽  
Extensor Digitorum ◽  
Hepatic Glycogen ◽  
Prolonged Starvation ◽  
Adductor Longus

We investigated the capacity for pyruvate oxidation in skeletal muscle, diaphragm and heart after starvation and re-feeding. Starvation for 48 h decreased pyruvate dehydrogenase (PDH) activity in soleus (by 47%), extensor digitorum longus (64%), gastrocnemius (86%), diaphragm (87%), adductor longus (90%), tibialis anterior (92%) and heart (99%). Chow re-feeding increased PDH activity in all muscles to 43-78% of the fed value within 2 h. However, complete re-activation was not observed for at least 4-6 h, during which time hepatic glycogen was replenished. We discuss the importance of muscle PDH activity in relation to sparing carbohydrate for hepatic glycogen synthesis.

scholarly journals Effects of dexamethasone treatment on insulin-stimulated rates of glycolysis and glycogen synthesis in isolated incubated skeletal muscles of the rat

1987 ◽  
Vol 246 (2) ◽  
pp. 551-554 ◽  
Author(s):  
B Leighton ◽  
R A J Challiss ◽  
F J Lozeman ◽  
E A Newsholme
Keyword(s):  
Soleus Muscle ◽  
Skeletal Muscles ◽  
Extensor Digitorum Longus ◽  
Glycogen Synthesis ◽  
Extensor Digitorum Longus Muscle ◽  
Extensor Digitorum ◽  
Hexose Transport ◽  
Dexamethasone Treatment ◽  
Longus Muscle ◽  
Lactate Formation

1. Rats were treated with dexamethasone for 4 days before measurement of the rates of lactate formation [which is an index of hexose transport; see Challiss, Lozeman, Leighton & Newsholme (1986) Biochem. J. 233, 377-381] and glycogen synthesis in response to various concentrations of insulin in isolated incubated soleus and extensor digitorum longus muscle preparations. 2. The concentration of insulin required to stimulate these processes half-maximally in soleus and extensor digitorum longus muscles isolated from control rats was about 100 muunits/ml. 3. Dexamethasone increases the concentration of insulin required to stimulate glycolysis half-maximally in soleus and extensor digitorum longus preparations to 250 and 300 muunits/ml respectively. The respective insulin concentrations necessary to stimulate glycogen synthesis half-maximally were about 430 and 370 muunits/ml for soleus and extensor digitorum longus muscle preparations isolated from steroid-treated rats. 5. Dexamethasone treatment did not change the amount of insulin bound to soleus muscle.

Effect of overexpressing GLUT-1 and GLUT-4 on insulin- and contraction-stimulated glucose transport in muscle

1996 ◽  
Vol 271 (3) ◽  
pp. E547-E555 ◽  
Author(s):  
E. Johannsson ◽  
K. J. McCullagh ◽  
X. X. Han ◽  
P. K. Fernando ◽  
J. Jensen ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Glucose Transport ◽  
Tibialis Anterior ◽  
Skeletal Muscles ◽  
Extensor Digitorum Longus ◽  
Muscle Contractions ◽  
Extensor Digitorum ◽  
Glut 1 ◽  
Glut 4 ◽  
Chronic Electrical Stimulation

To examine the effects of GLUT-1 on GLUT-4-dependent, insulin-stimulated, and contraction-stimulated 2-deoxy-D-glucose (2-DG) transport, we overexpressed GLUT-1 in metabolically heterogeneous skeletal muscles [red and white tibialis anterior (TA) and extensor digitorum longus (EDL)] via 7 days of chronic electrical stimulation. GLUT-1 was increased 1.6- to 16.4-fold (P < 0.05). Basal 2-DG transport was increased 1.7- to 3.0-fold (P < 0.05) and was equal to (red TA and EDL; P > 0.05) or exceeded insulin-stimulated 2-DG transport by 50% (white TA; P < 0.05) in the control muscles. GLUT-4 was concomitantly overexpressed (2.1- to 4.4-fold; P < 0.05). Insulin-stimulated 2-DG transport was increased 1.6- to 2.5-fold (P < 0.05). During muscle contractions, 2-DG transport increased 9- to 12-fold (P < 0.05) in control muscles, but this was reduced by approximately 25% (P < 0.05) in muscles overexpressing GLUT-1 and GLUT-4 (red TA and EDL). In contrast, in the experiment, white TA contraction-stimulated 2-DG transport was increased 1.7-fold (P < 0.05). Therefore, overexpression of GLUT-1, when GLUT-4 is also overexpressed, does not impair insulin-stimulated 2-DG transport, although contraction-stimulated transport may be reduced in some muscles.

Capillarity and blood flow of transplanted skeletal muscles of cats

1981 ◽  
Vol 241 (4) ◽  
pp. H630-H636 ◽  
Author(s):  
T. P. White ◽  
L. C. Maxwell ◽  
D. M. Sosin ◽  
J. A. Faulkner
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Skeletal Muscles ◽  
Extensor Digitorum Longus ◽  
Muscle Fibers ◽  
Extensor Digitorum ◽  
Maximal Flow ◽  
Total N ◽  
Total Ischemia ◽  
Peripheral Areas

After transplantation, skeletal muscle fibers and the microvasculature degenerate and then regenerate. The structural and functional characteristics of autografted muscle change with time and ultimately stabilize. Capillarity, blood flow, or fatigability was measured in control (total n = 22) and in autografted (total n = 42) extensor digitorum longus muscles of cats. From 10 to 180 days after transplantation, the capillaries per square millimeter in peripheral areas of autografts averaged 65% of control, and from 180 to 518 days, 45% of control. Resting blood flow in autografts increased eventually from total ischemia at the time of transplantation to values 400% of control. After 400 days, resting blood flow returned to control values. The blood flow of autografts increased in response to twitch stimulation, reaching maximal value (24.4 +/- 1.4 ml . 100 g-1 . min-1) at 1 twitch . s-1 . The maximal blood flow of autografts was comparable to the submaximal blood flow at 1 twitch . s-2 of controls and was 30% of the maximal flow of controls obtained at 4 twitches . s-1. The maximal blood flow in autografts did not increase from 80 to 460 days. When stimulated with repetitive twitches, autografts fatigued more rapidly than controls.

Anabolic responsiveness of skeletal muscles correlates with androgen receptor protein but not mRNA

2006 ◽  
Vol 84 (2) ◽  
pp. 273-277 ◽  
Author(s):  
Douglas A. Monks ◽  
Will Kopachik ◽  
S. Marc Breedlove ◽  
Cynthia L. Jordan
Keyword(s):  
Skeletal Muscle ◽  
Androgen Receptor ◽  
Skeletal Muscles ◽  
Extensor Digitorum Longus ◽  
Levator Ani ◽  
Extensor Digitorum ◽  
Receptor Protein ◽  
Mrna Levels ◽  
Receptor Mrna ◽  
Androgen Receptor Protein

Anabolic effects of androgens on skeletal muscle are well documented, but the physiological and biochemical bases of these effects are poorly understood. Skeletal muscles that differ in their androgen responsiveness can be used to examine these mechanisms. We compared androgen receptor mRNA and protein levels of the rat levator ani, a perineal skeletal muscle that depends on androgens for its normal maintenance and function with that of the rat extensor digitorum longus, a limb muscle that does not require androgens. Western immunoblotting indicated that androgen receptor protein is significantly elevated in the levator ani relative to the extensor digitorum longus. Surprisingly, steady state androgen receptor mRNA levels were equivalent in these muscles, as determined by Northern blot analysis and quantitative RT-PCR. These results suggest that androgen responsiveness of skeletal muscles is determined by the level of androgen receptor protein in a particular muscle and that androgen receptor protein content is regulated by translational or post-translational mechanisms.

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.

Abundance and subcellular distribution of MCT1 and MCT4 in heart and fast-twitch skeletal muscles

2000 ◽  
Vol 278 (6) ◽  
pp. E1067-E1077 ◽  
Author(s):  
Arend Bonen ◽  
Dragana Miskovic ◽  
Mio Tonouchi ◽  
Kathleen Lemieux ◽  
Marieangela C. Wilson ◽  
...  
Keyword(s):  
Subcellular Distribution ◽  
Tibialis Anterior ◽  
Skeletal Muscles ◽  
Inverse Relationship ◽  
Extensor Digitorum Longus ◽  
Plasma Membranes ◽  
Rat Hearts ◽  
T Tubules ◽  
Fast Twitch ◽  
White Gastrocnemius

The expression of two monocarboxylate transporters (MCTs) was examined in muscle and heart. MCT1 and MCT4 proteins are coexpressed in rat skeletal muscles, but only MCT1 is expressed in rat hearts. Among six rat fast-twitch muscles (red and white gastrocnemius, plantaris, extensor digitorum longus, red and white tibialis anterior) there was an inverse relationship between MCT1 and MCT4 ( r = −0.94). MCT1 protein was correlated with MCT1 mRNA ( r = 0.94). There was no relationship between MCT4 mRNA and MCT4 protein. MCT1 ( r = −0.97) and MCT4 ( r = 0.88) protein contents were correlated with percent fast-twitch glycolytic fiber. When normalized for their mRNAs, MCT1 but not MCT4 was still correlated with the percent fast-twitch glycolytic fiber composition of rat muscles ( r = −0.98). MCT1 and MCT4 were also measured in plasma membranes (PM), triads (TR), T tubules (TT), sarcoplasmic reticulum (SR), and intracellular membranes (IM). There was an intracellular pool of MCT4 but not of MCT1. The MCT1 subcellular distribution was as follows: PM (100%) > TR (31.6%) > SR (15%) = TT (14%) > IM (1.7%). The MCT4 subcellular distribution was considerably different [PM (100%) > TR (66.5%) > TT (36%) = SR (43%) > IM (24%)]. These studies have shown that 1) the mechanisms regulating the expression of MCT1 (transcriptional and posttranscriptional) and MCT4 (posttranscriptional) are different and 2) differences in MCT1 and MCT4 expression among muscles, as well as in their subcellular locations, suggest that they may have different roles in muscle.

scholarly journals Activity of mu- and m-calpain in regenerating fast and slow twitch skeletal muscles.

1996 ◽  
Vol 43 (4) ◽  
pp. 693-700 ◽  
Author(s):  
J Moraczewski ◽  
E Piekarska ◽  
M Zimowska ◽  
M Sobolewska
Keyword(s):  
Intracellular Calcium ◽  
Soleus Muscle ◽  
Muscle Regeneration ◽  
Skeletal Muscles ◽  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Slow Twitch ◽  
Edl Muscle ◽  
Calpain Ii ◽  
Complete Regeneration

Calpains--non-lysosomal intracellular calcium-activated neutral proteinases, form a family consisting of several distinct members. Two of the isoenzymes: mu (calpain I) and m (calpain II) responded differently to the injury during complete regeneration of Extensor digitorum longus (EDL) muscle and partial regeneration of Soleus muscle. In the crushed EDL the level of m-calpain on the 3rd and 7th day of regeneration was higher than in non-operated muscles, whereas the activity of this calpain in injured Soleus decreased. The level of mu-calpain in EDL oscillated irregularly during regeneration whereas in Soleus of both injured and contralateral muscles its level rapidly rose. Our results support the hypothesis that m-calpain is involved in the process of fusion of myogenic cells whereas mu-calpain plays a significant but indirect role in muscle regeneration.

Spaceflight on STS-48 and earth-based unweighting produce similar effects on skeletal muscle of young rats

1993 ◽  
Vol 74 (5) ◽  
pp. 2161-2165 ◽  
Author(s):  
M. E. Tischler ◽  
E. J. Henriksen ◽  
K. A. Munoz ◽  
C. S. Stump ◽  
C. R. Woodman ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Extensor Digitorum Longus ◽  
Space Shuttle ◽  
Weight Bearing ◽  
Similar Rate ◽  
Extensor Digitorum ◽  
Hindlimb Suspension ◽  
Albino Rats ◽  
Sprague Dawley ◽  
Ambient Temperatures

Our knowledge of the effects of unweighting on skeletal muscle of juvenile rapidly growing rats has been obtained entirely by using hindlimb-suspension models. No spaceflight data on juvenile animals are available to validate these models of simulated weightlessness. Therefore, eight 26-day-old female Sprague-Dawley albino rats were exposed to 5.4 days of weightlessness aboard the space shuttle Discovery (mission STS-48, September 1991). An asynchronous ground control experiment mimicked the flight cage condition, ambient shuttle temperatures, and mission duration for a second group of rats. A third group of animals underwent hindlimb suspension for 5.4 days at ambient temperatures. Although all groups consumed food at a similar rate, flight animals gained a greater percentage of body mass per day (P < 0.05). Mass and protein data showed weight-bearing hindlimb muscles were most affected, with atrophy of the soleus and reduced growth of the plantaris and gastrocnemius in both the flight and suspended animals. In contrast, the non-weight-bearing extensor digitorum longus and tibialis anterior muscles grew normally. Earlier suspension studies showed that the soleus develops an increased sensitivity to insulin during unweighting atrophy, particularly for the uptake of 2-[1,2–3H]deoxyglucose. Therefore, this characteristic was studied in isolated muscles within 2 h after cessation of spaceflight or suspension. Insulin increased uptake 2.5- and 2.7-fold in soleus of flight and suspended animals, respectively, whereas it increased only 1.6-fold in control animals. In contrast, the effect of insulin was similar among the three groups for the extensor digitorum longus, which provides a control for potential systemic differences in the animals.

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