Glycogen replenishment following exercise: effects of denervation and tenotomy

1975 ◽  
Vol 38 (6) ◽  
pp. 961-964 ◽  
Author(s):  
R. A. Ratliff ◽  
D. R. Lamb
Keyword(s):  
Nerve Impulse ◽  
Neural Tissue ◽  
Exhaustive Exercise ◽  
Synthetase Activity ◽  
Glycogen Synthetase ◽  
Denervated Muscles ◽  
Gastrocnemius Muscles ◽  
Glycogen Stores ◽  
Nerve Impulse Conduction

To examine the role of the nervous system in the rapid replenishment of muscle glycogen that occurs after exhaustive exercise, glycogen stores and glycogen synthetase activity of normal gastrocnemius muscles of untrained and trained guinea pigs were compared to glycogen and synthetase activity of trained gastrocnemius muscles that were denervated or tenotomized immediately after exhaustive exercise and then allowed to recover for 48 h. The trained tenotomized muscles, but not the denervated muscles, had significantly (P smaller than 0.05) less glycogen than the trained normal muscles. These results suggest that neither nerve impulse conduction nor tropic substances contained in neural tissue proximal to the site of denervation mediate glycogen replenishment after exercise. The active, glucose 6-phosphate independent (I) form of glycogen synthetase activity was reduced by both denervation and tenotomy at 48 h after exercise with no significant (P greater than 0.05) differences detected for the total of I and D (glucose 6-phosphate dependent) synthetase activity. Synthetase I relative to total synthetase activity was similar in trained and untrained normal muscles, both of which had significantly (P smaller than 0.05) greater relative I activities than denervated or tenotomized muscles. These synthetase data show that elevated glycogen stores following recovery from exercise may be observed in the absence of increased levels of glycogen synthetase activity.

scholarly journals The Role of Lactic Acid Accumulation in Muscle Fatigue of Two Species of Anurans, Xenopus Laevis and Rana Pipiens

1979 ◽  
Vol 82 (1) ◽  
pp. 35-51
Author(s):  
ROBERT W. PUTNAM
Keyword(s):  
Lactic Acid ◽  
Control Value ◽  
Hindlimb Muscles ◽  
Lactic Acid Content ◽  
Acid Accumulation ◽  
Intense Activity ◽  
Gastrocnemius Muscles ◽  
Glycogen Stores

Fatigue produced a marked increase in the lactic acid content of hindlimb muscles, the blood, and the whole animal. After 15 min of rest there was little decline of lactic acid levels but the animals could be stimulated into about 3 min of intense activity. This re-fatigue produced a further increase in lactic acid levels. Gastrocnemius muscles removed from fatigued frogs and stimulated in vitro were able to generate initial tensions similar to those in control muscles; total tension was about a third of the control value. In vitro stimulation of these muscles from fatigued frogs led to additional accumulation of lactic acid. Fatigue produced little decrease in the glycogen content of muscles in X. laevis but a marked decrease in R. pipiens. Considerable glycogen stores remained even in the muscles of re-fatigued animals. These data show that accumulation of lactic acid in muscle or blood, depletion of glycogen in muscle, or change in blood pH cannot account for fatigue in these species. Possible other causes of fatigue are discussed.

scholarly journals Fat balance in obese subjects: role of glycogen stores

1998 ◽  
Vol 274 (6) ◽  
pp. E1027-E1033 ◽  
Author(s):  
Patrick Schrauwen ◽  
Wouter D. Van Marken Lichtenbelt ◽  
Wim H. M. Saris ◽  
Klaas R. Westerterp
Keyword(s):  
Fat Oxidation ◽  
Exhaustive Exercise ◽  
Fat Intake ◽  
Maximal Power Output ◽  
Respiration Chamber ◽  
Obese Subjects ◽  
Healthy Obese ◽  
Glycogen Stores ◽  
Obese Male

In a previous study, we showed that lean subjects are capable of rapidly adjusting fat oxidation to fat intake on a high-fat (HF) diet when glycogen stores are lowered by exhaustive exercise. However, it has been proposed that obese subjects have impaired fat oxidation. We therefore studied the effect of low glycogen stores on fat oxidation after a switch from a reduced-fat (RF) diet to an HF diet in obese subjects. Ten healthy, obese male and female subjects (26 ± 2 yr, body mass index 31.8 ± 1.4, maximal power output 228 ± 14 W) consumed an RF diet (30, 55, and 15% of energy from fat, carbohydrate, and protein, respectively) at home for 3 days on four occasions ( days 1–3). On two occasions, subjects came to the laboratory on day 3 at 1500 to perform an exhaustive glycogen-lowering exercise test (Ex), after which they went into a respiration chamber for a 36-h stay. On the other two occasions, subjects directly entered the respiration chamber at 1800 for a 36-h stay. In the respiration chamber, they were fed, in energy balance, either an HF diet (60, 25, and 15% of energy from fat, carbohydrate, and protein, respectively) or an RF diet. All diets were consumed as breakfast, lunch, dinner, and two or more snacks per day. Twenty-four-hour respiratory quotient was 0.91 ± 0.01, 0.89 ± 0.01, 0.84 ± 0.01, and 0.81 ± 0.01 with RF diet, RF + Ex, HF, and HF + Ex treatments, respectively. With the HF treatment, fat oxidation was below fat intake, indicating the slow change of oxidation to intake on an HF diet. After the HF + Ex treatment, however, fat oxidation matched fat intake. In conclusion, obese subjects are capable of rapidly adjusting fat oxidation to fat intake when glycogen stores are lowered by exhaustive exercise.

scholarly journals Factors Affecting Muscle Glycogen Synthetase Activity

1967 ◽  
Vol 242 (6) ◽  
pp. 1227-1231
Author(s):  
Enrique Belocopitow ◽  
Maria del Carmen Garcia Fernandez ◽  
Lutz Birnbaumer ◽  
Héctor N. Torres
Keyword(s):  
Muscle Glycogen ◽  
Synthetase Activity ◽  
Factors Affecting ◽  
Glycogen Synthetase

scholarly journals The RelA hydrolase domain acts as a molecular switch for (p)ppGpp synthesis

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Anurag Kumar Sinha ◽  
Kristoffer Skovbo Winther
Keyword(s):  
Active Sites ◽  
Molecular Switch ◽  
Cell Physiology ◽  
Synthetase Activity ◽  
Wild Type ◽  
Functional Studies ◽  
Loop Region ◽  
A Site ◽  
Trna Binding

AbstractBacteria synthesize guanosine tetra- and penta phosphate (commonly referred to as (p)ppGpp) in response to environmental stresses. (p)ppGpp reprograms cell physiology and is essential for stress survival, virulence and antibiotic tolerance. Proteins of the RSH superfamily (RelA/SpoT Homologues) are ubiquitously distributed and hydrolyze or synthesize (p)ppGpp. Structural studies have suggested that the shift between hydrolysis and synthesis is governed by conformational antagonism between the two active sites in RSHs. RelA proteins of γ-proteobacteria exclusively synthesize (p)ppGpp and encode an inactive pseudo-hydrolase domain. Escherichia coli RelA synthesizes (p)ppGpp in response to amino acid starvation with cognate uncharged tRNA at the ribosomal A-site, however, mechanistic details to the regulation of the enzymatic activity remain elusive. Here, we show a role of the enzymatically inactive hydrolase domain in modulating the activity of the synthetase domain of RelA. Using mutagenesis screening and functional studies, we identify a loop region (residues 114–130) in the hydrolase domain, which controls the synthetase activity. We show that a synthetase-inactive loop mutant of RelA is not affected for tRNA binding, but binds the ribosome less efficiently than wild type RelA. Our data support the model that the hydrolase domain acts as a molecular switch to regulate the synthetase activity.

Anterior mesendoderm induces mouse Engrailed genes in explant cultures

Development ◽  
1993 ◽  
Vol 118 (1) ◽  
pp. 139-149 ◽  
Author(s):  
S.L. Ang ◽  
J. Rossant
Keyword(s):  
Direct Evidence ◽  
Neural Tissue ◽  
Explant Culture ◽  
Neural Plate ◽  
Explant Cultures ◽  
Neural Marker ◽  
Engrailed Genes ◽  
Anterior Posterior

We have developed germ layer explant culture assays to study the role of mesoderm in anterior-posterior (A-P) patterning of the mouse neural plate. Using isolated explants of ectodermal tissue alone, we have demonstrated that the expression of Engrailed-1 (En-1) and En-2 genes in ectoderm is independent of mesoderm by the mid- to late streak stage, at least 12 hours before their onset of expression in the neural tube in vivo at the early somite stage. In recombination explants, anterior mesendoderm from headfold stage embryos induces the expression of En-1 and En-2 in pre- to early streak ectoderm and in posterior ectoderm from headfold stage embryos. In contrast, posterior mesendoderm from embryos of the same stage does not induce En genes in pre- to early streak ectoderm but is able to induce expression of a general neural marker, neurofilament 160 × 10(3) M(r). These results provide the first direct evidence for a role of mesendoderm in induction and regionalization of neural tissue in mouse.

AMP kinase is not required for the GLUT4 response to exercise and denervation in skeletal muscle

2004 ◽  
Vol 287 (4) ◽  
pp. E739-E743 ◽  
Author(s):  
Burton F. Holmes ◽  
David B. Lang ◽  
Morris J. Birnbaum ◽  
James Mu ◽  
G. Lynis Dohm
Keyword(s):  
Skeletal Muscle ◽  
Dominant Negative ◽  
Treadmill Running ◽  
Wild Type ◽  
Α Subunit ◽  
Ampk Activity ◽  
Denervated Muscles ◽  
Amp Activated Protein Kinase ◽  
Response To Exercise

An acute bout of exercise increases muscle GLUT4 mRNA in mice, and denervation decreases GLUT4 mRNA. AMP-activated protein kinase (AMPK) activity in skeletal muscle is also increased by exercise, and GLUT4 mRNA is increased in mouse skeletal muscle after treatment with AMPK activator 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside(AICAR). These findings suggest that AMPK activation might be responsible for the increase in GLUT4 mRNA expression in response to exercise. To investigate the role of AMPK in GLUT4 regulation in response to exercise and denervation, transgenic mice with a mutated AMPK α-subunit (dominant negative; AMPK-DN) were studied. GLUT4 did not increase in AMPK-DN mice that were treated with AICAR, demonstrating that muscle AMPK is inactive. Exercise (two 3-h bouts of treadmill running separated by 1 h of rest) increased GLUT4 mRNA in both wild-type and AMPK-DN mice. Likewise, denervation decreased GLUT4 mRNA in both wild-type and AMPK-DN mice. GLUT4 mRNA was also increased by AICAR treatment in both the innervated and denervated muscles. These data demonstrate that AMPK is not required for the response of GLUT4 mRNA to exercise and denervation.

Role of plasma epinephrine in fasted exercising rats

1985 ◽  
Vol 248 (3) ◽  
pp. R302-R307 ◽  
Author(s):  
W. W. Winder ◽  
M. L. Terry ◽  
V. M. Mitchell
Keyword(s):  
Physiological Role ◽  
Quadriceps Muscle ◽  
Type I ◽  
Type Ii ◽  
Plasma Epinephrine ◽  
Lateral Gastrocnemius ◽  
White Region ◽  
Gastrocnemius Muscles ◽  
Fast Twitch

We have investigated the physiological role of the marked increase in plasma epinephrine that occurs in fasted exercising rats. Fasted adrenodemedullated (ADM) rats show a marked reduction in endurance run times compared with sham-operated (SO) controls. After running for 30 min at 21 m/min up a 10% grade, ADM rats' blood glucose was 2.9 +/- 0.1 mM vs. 4.3 +/- 0.2 mM in SO rats. At the same time, blood lactate was 3.0 +/- 0.2 mM in SO rats compared with 1.0 +/- 0.1 mM in ADM rats. Glycogenolysis was impaired in ADM rats in the fast-twitch white region of the quadriceps, lateral gastrocnemius, and soleus muscles but not in the fast-twitch red region of the quadriceps muscle. Hepatic adenosine 3',-5'-cyclic monophosphate was increased to the same extent in ADM and SO rats during exercise. Infusion of epinephrine into ADM rats during exercise corrected the hypoglycemia, restored lactate to normal, and stimulated glycogenolysis in soleus, white quadriceps, and lateral gastrocnemius muscles. Epinephrine-dependent glycogenolysis in contracting type I and noncontracting type II muscle fibers apparently provides essential quantities of lactate for hepatic gluconeogenesis in fasted exercising rats.

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