The Effect of Shortening on Energy Liberation and High Energy Phosphate Hydrolysis in Frog Skeletal Muscle

1984 ◽  
pp. 865-881 ◽  
Author(s):  
Earl Homsher ◽  
M. Irving ◽  
T. Yamada
Keyword(s):  
Skeletal Muscle ◽  
High Energy ◽  
Energy Liberation ◽  
Frog Skeletal Muscle ◽  
High Energy Phosphate ◽  
Phosphate Hydrolysis

Differential energetic response of brain vs. skeletal muscle upon glycemic variations in healthy humans

2008 ◽  
Vol 294 (1) ◽  
pp. R12-R16 ◽  
Author(s):  
Kerstin M. Oltmanns ◽  
Uwe H. Melchert ◽  
Harald G. Scholand-Engler ◽  
Maria C. Howitz ◽  
Bernd Schultes ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Underlying Mechanism ◽  
High Energy ◽  
Resonance Spectroscopy ◽  
Energy Status ◽  
High Energy Phosphate ◽  
Available Energy ◽  
Healthy Humans ◽  
High Energy Phosphate Metabolism ◽  
The Brain

The brain regulates all metabolic processes within the organism, and therefore, its energy supply is preserved even during fasting. However, the underlying mechanism is unknown. Here, it is shown, using 31P-magnetic resonance spectroscopy that during short periods of hypoglycemia and hyperglycemia, the brain can rapidly increase its high-energy phosphate content, whereas there is no change in skeletal muscle. We investigated the key metabolites of high-energy phosphate metabolism as rapidly available energy stores by 31P MRS in brain and skeletal muscle of 17 healthy men. Measurements were performed at baseline and during dextrose or insulin-induced hyperglycemia and hypoglycemia. During hyperglycemia, phosphocreatine (PCr) concentrations increased significantly in the brain ( P = 0.013), while there was a similar trend in the hypopglycemic condition ( P = 0.055). Skeletal muscle content remained constant in both conditions ( P > 0.1). ANOVA analyses comparing changes from baseline to the respective glycemic plateau in brain (up to +15%) vs. muscle (up to −4%) revealed clear divergent effects in both conditions ( P < 0.05). These effects were reflected by PCr/Pi ratio ( P < 0.05). Total ATP concentrations revealed the observed divergency only during hyperglycemia ( P = 0.018). These data suggest that the brain, in contrast to peripheral organs, can activate some specific mechanisms to modulate its energy status during variations in glucose supply. A disturbance of these mechanisms may have far-reaching implications for metabolic dysregulation associated with obesity or diabetes mellitus.

scholarly journals A temporal dissociation of energy liberation and high energy phosphate splitting during shortening in frog skeletal muscles.

1976 ◽  
Vol 68 (1) ◽  
pp. 13-27 ◽  
Author(s):  
J A Rall ◽  
E Homsher ◽  
A Wallner ◽  
W F Mommaerts
Keyword(s):  
Stimulus Pattern ◽  
Skeletal Muscles ◽  
Energy Production ◽  
Time Course ◽  
Rana Pipiens ◽  
High Energy ◽  
Energy Liberation ◽  
High Energy Phosphate ◽  
Contracting Muscle ◽  
Mechanical Measurements

Measurements of the time course of high energy phosphate splitting and energy liberation were performed on rapidly shortening Rana pipiens skeletal muscles. In muscles contracting 30 times against small loads (less the 0.02P), the ratio of explained heat + work (H + W) (calculated from the measured high energy phosphate splitting) to observed H + W (from myothermal and mechanical measurements) was 0.68 +/- 0.08 and is in agreement with results obtained in isometric tetani of R. pipiens skeletal muscle. In lightly afterloaded muscles which were tetanized for 0.6a and whose metabolism was arrested at 3.0 s after the beginning of stimulation, a similar ratio of explained H + W to observed H + W was obtained. However, in identical contractions in which metabolism was arrested at 0.5-0.75 s after the beginning of stimulation, the ratio of explained H + W to observed H + W declined significantly to values ranging from 0.15 to 0.40. These results suggest that rapid shortening at the beginning of contraction induces a delay between energy production and measurable high energy phosphate splitting. This interpretation was tested and confirmed in experiments in which one muscle of a pair contracted isometrically while the other contracted against a small afterload. The afterload and stimulus pattern were arranged so that at the time metabolism was arrested, 0.5 s after the beginning of stimulation, the total energy production by both muscles was the same. Chemical analysis revealed that the isotonically contracting muscle spilt only 25% as much high energy phosphate as did the isometrically contracting muscle.

INFLUENCES OF THYROXINE AND INSULIN ON THE TURNOVER AND FATE OF HIGH-ENERGY PHOSPHATE

1964 ◽  
Vol 42 (6) ◽  
pp. 777-786 ◽  
Author(s):  
Dorothy S. Dow
Keyword(s):  
Skeletal Muscle ◽  
Energy Transfer ◽  
Adenosine Triphosphate ◽  
Cell Structure ◽  
Adenosine Diphosphate ◽  
High Energy ◽  
High Energy Phosphate ◽  
Nucleoside Phosphorylase ◽  
Mitochondrial Permeability ◽  
Energy Acceptor

Ingestion by the weanling rat of thyroxine in an amount greatly in excess of physiological requirements resulted in significant increases in the rates of turnover of the high-energy compounds phosphocreatine (PC), adenosine diphosphate (ADP), and adenosine triphosphate (ATP) and in significant decreases in their concentrations in skeletal muscle. Nucleoside phosphorylase and myokinase activities and rates of pyrophosphate splitting of ATP and of utilization of ATP for nuclear syntheses were unaltered in thyrotoxic muscle. The findings suggest that increased extramitochondrial utilization of ATP for glycolysis may be the factor responsible for the increased phosphorylating capacity of the thyrotoxic animal. An effect of thyroxine on mitochondrial permeability as well as on rate of formation of the high-energy intermediate would appear to explain the observed results.A further enhancement of the already markedly elevated thyrotoxic rate of phosphorylation was effected by the superimposition of insulin. Insulin also effected increases in the concentrations of the high-energy compounds. It is apparent that insulin acts by reducing the utilization of ATP for phosphorylation of glucose and thus increases the mitochondrial availability of high-energy acceptor. This increased mitochondrial affinity for high-energy compounds results in an enhancement of mitochondrial energy transfer processes.The findings appear to involve both thyroxine and insulin in the control of cell structure.

scholarly journals Skeletal muscle high energy phosphate metabolism in patients with obesity and impaired fasting blood glucose

2012 ◽  
Vol 14 (S1) ◽  
Author(s):  
Gurusher S Panjrath ◽  
Michael Schär ◽  
AbdEl-Monem El-Sharkawy ◽  
Steven P Schulman ◽  
Kerry Stewart ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Blood Glucose ◽  
Fasting Blood Glucose ◽  
High Energy ◽  
Phosphate Metabolism ◽  
High Energy Phosphate ◽  
High Energy Phosphate Metabolism

Energy metabolism of skeletal muscle biopsies stimulated anaerobically without load in vitro

1986 ◽  
Vol 250 (6) ◽  
pp. C813-C820 ◽  
Author(s):  
D. A. Young ◽  
M. M. Chi ◽  
O. H. Lowry
Keyword(s):  
Skeletal Muscle ◽  
High Energy ◽  
Mineral Oil ◽  
Metabolic Changes ◽  
High Energy Phosphate ◽  
Metabolic Capacity ◽  
Fast Twitch ◽  
Muscle Biopsies ◽  
Anaerobic System

This study was made to test the validity of a simple biopsy technique for assessing the metabolic capacity of skeletal muscle. The biopsy is stimulated under mineral oil without attachment, i.e., without load or tension, then freeze-clamped and assayed for ATP, phosphocreatine, glucose 6-phosphate, and lactate. The mineral oil creates a closed anaerobic system. Background studies demonstrated in the absence of a load, metabolic changes with stimulation were little affected by cutting the fibers to obtain the biopsy; and high-energy phosphate (approximately P) consumption during a brief tetanus was not much lower than that for an isometric tetanus. Individual fast-twitch oxidative-glycolytic (IIA) and fast-twitch glycolytic (IIB) fibers obtained from the freeze-clamped biopsy showed distinct differences in approximately P consumption and metabolic changes. The results indicate that this technique could be useful for studies of normal and pathological human muscle.

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