scholarly journals Specific ATPases drive compartmentalized glycogen utilization in rat skeletal muscle

2021 ◽  
Author(s):  
Joachim Nielsen ◽  
Peter Dubillot ◽  
Marie-Louise Holleufer Stausholm ◽  
Niels Ortenblad
Keyword(s):  
Skeletal Muscle ◽  
Glycogen Metabolism ◽  
Local Energy ◽  
New Paradigm ◽  
Energy Substrate ◽  
Transmission Electron ◽  
Energy Consuming ◽  
Glycogen Utilization ◽  
Glycogen Particles ◽  
Subcellular Level

Glycogen is a key energy substrate in excitable tissue and especially in skeletal muscle fibers it contributes with a substantial, but also local energy production. A heterogenic subcellular distribution of three distinct glycogen pools in skeletal muscle is proved by transmission electron microscopy (TEM), which is thought to represent the requirements for local energy stores at the subcellular level. Here, we show that the three main energy-consuming ATPases in skeletal muscles (Ca2+-, Na+,K+-, and myosin ATPases) utilize different local pools of glycogen. These results clearly demonstrate compartmentalized glycogen metabolism and emphasize that spatially distinct pools of glycogen particles act as energy substrate for separated energy requiring processes, suggesting a new paradigm for understanding glycogen metabolism in working muscles, muscle fatigue and metabolic disorders.

Effect of estradiol on tissue glycogen metabolism in exercised oophorectomized rats

1987 ◽  
Vol 63 (2) ◽  
pp. 492-496 ◽  
Author(s):  
Z. V. Kendrick ◽  
C. A. Steffen ◽  
W. L. Rumsey ◽  
D. I. Goldberg
Keyword(s):  
Skeletal Muscle ◽  
Exercise Performance ◽  
Sunflower Oil ◽  
Glycogen Content ◽  
Vastus Lateralis ◽  
Glycogen Metabolism ◽  
Submaximal Exercise ◽  
Total Work ◽  
Glycogen Utilization ◽  
Glycogen Sparing

The effect of both physiological and pharmacological doses of estradiol on exercise performance and tissue glycogen utilization was determined in oophorectomized estradiol-replaced (ER) rats. Doses of beta-estradiol 3-benzoate (0.02, 0.04, 0.1, 0.2, 1, 2, 4, or 10 micrograms.0.1 ml of sunflower oil-1.100 g body wt-1) were injected 5 days/wk for 4 wk. Controls were sham injected (SI). After treatment, the animals were run to exhaustion on a motorized treadmill. ER animals receiving the 0.02-microgram dose ran significantly longer and completed more total work than the SI group. ER animals receiving doses of greater than or equal to 0.04 microgram ran longer and performed more work than the 0.02-microgram group. At exhaustion, myocardial glycogen content was significantly decreased in animals that were ER with less than or equal to 0.1 microgram, whereas those replaced with doses greater than 0.1 microgram utilized significantly less glycogen. With the 10-micrograms dose no significant decrease in heart glycogen content was observed at exhaustion. A submaximal 2-h run significantly reduced glycogen content in heart, red and white portions of the vastus lateralis, and the livers of SI animals. The latter effect was attenuated in skeletal muscle and liver, and there was no effect in the hearts of the ER animals receiving 2 micrograms. These data indicate that estradiol replacement in oophorectomized rats influenced myocardial glycogen utilization during exhaustive exercise and spared tissue glycogen during submaximal exercise. These glycogen sparing effects may have contributed to the significant improvements in exercise performance observed in this study.

Internal defibrillation with minimal skeletal muscle activation: A new paradigm toward painless defibrillation

Heart Rhythm ◽  
2005 ◽  
Vol 2 (10) ◽  
pp. 1108-1113 ◽  
Author(s):  
Vinod Jayam ◽  
Menekhem Zviman ◽  
Venku Jayanti ◽  
Ariel Roguin ◽  
Henry Halperin ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Activation ◽  
New Paradigm ◽  
Internal Defibrillation

Increased concentrations of glycogen synthase protein in skeletal muscle of patients with NIDDM

1995 ◽  
Vol 269 (1) ◽  
pp. E27-E32 ◽  
Author(s):  
M. Lofman ◽  
H. Yki-Jarvinen ◽  
M. Parkkonen ◽  
J. Lindstrom ◽  
L. Koranyi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Metabolism ◽  
Protein Concentration ◽  
Glycogen Synthase ◽  
Glycogen Metabolism ◽  
Dependent Diabetes Mellitus ◽  
Euglycemic Hyperinsulinemic Clamp ◽  
Control Subjects ◽  
Significant Difference ◽  
Glycogen Synthase Activity

To examine whether changes in the glycogen synthase protein concentration contribute to impaired insulin-stimulated glycogen metabolism in patients with noninsulin-dependent diabetes mellitus (NIDDM), muscle biopsies were taken before and after a 4-h euglycemic hyperinsulinemic clamp to measure glycogen synthase activity and glycogen synthase protein concentrations in 14 patients with NIDDM and in 17 control subjects. Nonoxidative glucose metabolism was reduced by 64% in patients with NIDDM compared with control subjects and correlated with insulin-stimulated glycogen synthase activity (r = 0.55, P < 0.05). The concentration of glycogen synthase protein in skeletal muscle was higher in patients with NIDDM than in control subjects (6.75 +/- 0.88 vs. 4.41 +/- 0.50 counts.min-1.micrograms protein-1, P < 0.05), whereas there was no significant difference in glycogen synthase mRNA concentration between the two groups. The glycogen synthase protein concentration correlated inversely with the rate of nonoxidative glucose metabolism (r = -0.63, P < 0.05). These findings indicate that the amount of glycogen synthase protein is increased in skeletal muscle of patients with NIDDM. The increase in the glycogen synthase protein may serve to compensate for a functional defect in the activation of the enzyme by insulin.

scholarly journals The effects of simulated microgravity on skeletal muscle of Japanese quail: transmission electron microscopic study

2011 ◽  
Vol 80 (1) ◽  
pp. 119-124 ◽  
Author(s):  
Katarína Holovská ◽  
Viera Almášiová ◽  
Viera Cigánková ◽  
Peter Škrobánek
Keyword(s):  
Skeletal Muscle ◽  
Japanese Quail ◽  
Structural Changes ◽  
Simulated Microgravity ◽  
Negative Impact ◽  
Electron Microscopic ◽  
Giant Mitochondria ◽  
Transmission Electron ◽  
Muscle Tissues ◽  
And Control

The aim of the present study was to investigate the effects of simulated microgravity (hypodynamia) on the structure of the skeletal muscle (m. gastrocnemius) in developing Japanese quail by transmission electron microscopy. Samples of muscle tissues from experimental (n = 28) and control (n = 28) birds were collected at day 7, 14, 28, 42 and 56 of age. The structure of m. gastrocnenmius was changed depending on hypodynamia length. The first extensive structural changes were found on day 14 of age. The mitochondria were enlarged and the spaces between the myofibrils were slightly extended compared to control. The sarcomeres were irregular and lipid droplets occurred in the sarcoplasm. Further developmental changes occurred on day 28 of age. Mitochondria fused into the giant mitochondria which frequently exceeded the length of one sarcomere. Moreover, at 42 days of age, beside the above mentioned changes, sarcoplasmic reticulum was dilated and the number of mitochondrial cristae was reduced. However, the structure of m. gastrocnemius on day 56 was less damaged compared to the damage observed on day 42 of age. Presented results indicate that the continuous stay of male Japanese quail under simulated microgravity has a negative impact on the structure of m. gastrocnemius, but also the ability of muscle tissue to cope with these specific conditions.

scholarly journals Localization of cations by pyroantimonate. II. Electron probe microanalysis of calcium and sodium in skeletal muscle of mouse.

1988 ◽  
Vol 36 (1) ◽  
pp. 55-64 ◽  
Author(s):  
P Mentré ◽  
S Halpern
Keyword(s):  
Skeletal Muscle ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Glycogen Metabolism ◽  
Ultrastructural Level ◽  
High Rate ◽  
Cell Structures ◽  
Means Of Transmission ◽  
New Formulation ◽  
Optical Level

A new formulation of the pyroantimonate (PA) method for localization of calcium and sodium is proposed and evaluated in mouse skeletal muscle. This study, performed at the ultrastructural level by means of transmission electron microscopy (TEM) and electron probe microanalysis (EPMA), completes a previous work done at the optical level with analytical ion microscopy (AIM), which enabled us to define the appropriate composition of fixatives. In our present experiments, calcium and sodium were shown localized in various cell structures, e.g., T-tubules, glycogen, granules, nuclei. For AIM, the best fixatives were characterized by PA supersaturation, which resulted in smaller crystals and a high rate of penetration in the presence of paraformaldehyde and either phenol or collidine. Contrary to the findings at the optical level, collidine did not give satisfactory results at the ultrastructural level. The method of floating sections on the microtome trough was an important cause of cation displacement. We found that alkalinization of the floating medium significantly decreased ion loss. The technique also provided an indication of the form of these elements: free or easily liberated cations were precipitated into coarse PA deposits; electron-positive chelates were "stained" by PA; neutral chelates were not stained, but some of them could be detected by EPMA. This PA method should make possible more precise localization of cellular calcium, such as in glycogen metabolism, and perhaps detection of movements of cytoplasmic calcium and sodium.

Effect of estradiol on tissue glycogen metabolism and lipid availability in exercised male rats

1991 ◽  
Vol 71 (5) ◽  
pp. 1694-1699 ◽  
Author(s):  
Z. V. Kendrick ◽  
G. S. Ellis
Keyword(s):  
Fatty Acids ◽  
Body Weight ◽  
Exercise Performance ◽  
Glycogen Content ◽  
Day Treatment ◽  
Glycogen Metabolism ◽  
Liver Glycogen ◽  
Male Rats ◽  
Plasma Lactate ◽  
Glycogen Utilization

The effect of 17 beta-estradiol 3-benzoate (10 micrograms.0.1 ml sunflower oil-1.100 g body wt-1) on exercise performance, tissue glycogen utilization, and lipid availability was determined in male rats. In experiment 1, estradiol or oil was administered 1 h or 1–6 days before a treadmill run to exhaustion. No differences in body weight between oil- and estradiol-administered animals were observed during the 6-day treatment. Animals receiving estradiol for 3–6 days ran significantly longer and completed more work than oil-administered animals. Significant degradation of red and white vastus muscle, myocardial, and liver glycogen was observed in all animals run to exhaustion. In experiment 2, animals were administered estradiol for 5 days and then run for 2 h. The submaximal run for 2 h significantly reduced tissue glycogen content in red and white vastus muscle, heart, and liver of oil-administered animals. The latter effect was attenuated in both vastus muscles, liver, and myocardial tissues in the estradiol-administered animals. Estradiol administration significantly increased plasma fatty acids and lowered plasma lactate during the submaximal run. These data indicate that when body weight remained constant between groups of male rats, estradiol administration for 3–6 days increased exercise performance. Furthermore, estradiol administration for 5 days resulted in greater lipid availability and less tissue glycogen utilization during submaximal running for 2 h.

Stem Without Spherical Aberration

1999 ◽  
Vol 5 (S2) ◽  
pp. 670-671 ◽  
Author(s):  
O.L. Krivanek ◽  
N. Dellby ◽  
A.R. Lupini
Keyword(s):  
Spherical Aberration ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Operating Voltage ◽  
Resolution Limit ◽  
New Paradigm ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Two Generations

Even though two generations of electron microscopists have come to accept that the resolution of their instruments is limited by spherical aberration, three different aberration correctors showing that the aberration can be overcome have recently been built [1-3]. One of these correctors was developed by us specifically for forming small electron probes in a dedicated scanning transmission electron microscope (STEM) [3, 4]. It promises to revolutionize the way STEM instruments are built and the types of problems that they are applied to.As was the case with the Berlin Wall, when a barrier that was once thought immovable finally crumbles, many of the consequences can be quite unexpected. For STEM, the removal of spherical aberration (Cs) as the main resolution limit is likely to lead to a new paradigm in which:1) The resolution at a given operating voltage will improve by about 3x relative to today's best. When Cs can be adjusted arbitrarily in a STEM being used for microanalysis or dark field imaging, defocus and Cs are set to values that optimally oppose the effect of the 5th-order spherical aberration C5.

scholarly journals Ischemic Tolerance in Pre-Myelinated White Matter: The Role of Astrocyte Glycogen in Brain Pathology

2015 ◽  
Vol 35 (6) ◽  
pp. 951-958 ◽  
Author(s):  
Robert Fern
Keyword(s):  
White Matter ◽  
Neural Development ◽  
Energy Supply ◽  
Necessary Conditions ◽  
Volume Fraction ◽  
Glycogen Metabolism ◽  
Ischemic Tolerance ◽  
Mitochondrial Volume ◽  
Glycogen Particles

In isolated white matter, ischemic tolerance changes dramatically in the period immediately before the onset of myelination. In the absence of an extrinsic energy source, postnatal day 0 to 2 (P0 to P2) white matter axons are here shown to maintain excitability for over twice as long as axons > P2, a differential that was dependent on glycogen metabolism. Prolonged withdrawal of extrinsic energy supply tended to spare axons in zones around astrocytes, which are shown to be the sole repository for glycogen particles in developing white matter. Analysis of mitochondrial volume fraction revealed that neither axons nor astrocytes had a low metabolic rate in neonatal white matter, while oligodendroglia at older ages had an elevated metabolism. The astrocyte population is established early in neural development, and exhibits reduced cell density as maturation progresses and white matter expands. The findings show that this event establishes the necessary conditions for ischemia sensitivity in white matter and indicates that astrocyte proximity may be significant for the survival of neuronal elements in conditions associated with compromised energy supply.

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