Glyconeogenic pathway in isolated skeletal muscles of rats

2002 ◽  
Vol 80 (2) ◽  
pp. 162-167 ◽  
Author(s):  
Analúcia Rampazzo Xavier ◽  
José Eduardo de Salles Roselino ◽  
Neusa Maria Zanon Resano ◽  
Maria Antonieta Rissato Garófalo ◽  
Renato Helios Migliorini ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Kinase ◽  
Muscle Glycogen ◽  
Skeletal Muscles ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Metabolic Flux ◽  
Maximal Activity ◽  
Reverse Direction ◽  
Long Time ◽  
Muscle Pyruvate Kinase

Although the conversion of lactate to glycogen (glyconeogenesis) in muscle was demonstrated a long time ago, the biochemical reactions responsible for this process are still a controversial matter. In the present study, advantage was taken from the specific inhibition induced by phenylalanine on muscle pyruvate kinase (PK) to investigate the role of reverse PK activity in muscle glyconeogenesis. Addition of phenylalanine to the incubation medium of a preparation of isolated, intact skeletal muscles that maintain metabolic activity for several hours reduced by 50% the rate of incorporation of [14C]lactate or [14C]bicarbonate into muscle glycogen. Muscle extracts presented high levels of maximal activity of PK in the reverse direction, which was completely blocked in the presence of phenylalanine. In contrast, mercaptopicolinic acid, an inhibitor of phosphoenolpyruvate carboxykinase (PEPCK), did not affect the incorporation of14C from either lactate or bicarbonate into muscle glycogen. Maximal PEPCK activity was much lower in muscle extracts than in gluconeogenic or glyceroneogenic tissues and was suppressed in the presence of mercaptopicolinic acid. The data suggest that a reversal of the metabolic flux through the reaction catalyzed by PK contributes to the accumulation of lactate-derived glycogen that occurs in skeletal muscle under certain physiological conditions.Key words: lactate, glyconeogenesis, skeletal muscle, reverse pyruvate kinase reaction, phenylalanine.

In vivo effect of Trigonella foenum graecum on the expression of pyruvate kinase, phosphoenolpyruvate carboxykinase, and distribution of glucose transporter (GLUT4) in alloxan-diabetic rats

2006 ◽  
Vol 84 (6) ◽  
pp. 647-654 ◽  
Author(s):  
Sameer Mohammad ◽  
Asia Taha ◽  
Kamal Akhtar ◽  
R.N.K. Bamezai ◽  
Najma Zaheer Baquer
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Kinase ◽  
Plasma Glucose ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Glucose Transporter ◽  
Diabetic Rats ◽  
Altered Expression ◽  
Glucose Levels ◽  
Glucose Transporter Glut4

Plasma glucose levels are maintained by a precise balance between glucose production and its use. Liver pyruvate kinase (PK) and phosphoenolpyruvate carboxykinase (PEPCK), 2 key enzymes of glycolysis and gluconeogenesis, respectively, play a crucial role in this glucose homeostasis along with skeletal muscle glucose transporter (GLUT4). In the diabetic state, this balance is disturbed owing to the absence of insulin, the principal factor controlling this regulation. In the present study, alloxan-diabetic animals having high glucose levels of more than 300 mmol/L have been taken and the administration of Trigonella seed powder (TSP) to the diabetic animals was assessed for its effect on the expression of PK and PEPCK in liver and GLUT4 distribution in skeletal muscle of alloxan-diabetic rats. TSP treatment to the diabetic animals resulted in a marked decrease in the plasma glucose levels. Trigonella treatment partially restored the altered expression of PK and PEPCK. TSP treatment also corrected the alterations in the distribution of GLUT4 in the skeletal muscle.

Some kinetic properties of skeletal muscle pyruvate kinase from air-breathing and water-breathing fish of the Amazon

1978 ◽  
Vol 56 (4) ◽  
pp. 751-758 ◽  
Author(s):  
J. H. A. Fields ◽  
W. R. Driedzic ◽  
C. J. French ◽  
P. W. Hochachka
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Kinase ◽  
Adenosine Diphosphate ◽  
Kinetic Properties ◽  
Air Breathing ◽  
Hoplias Malabaricus ◽  
Arapaima Gigas ◽  
Saturation Kinetics ◽  
Muscle Pyruvate Kinase ◽  
Hoplerythrinus Unitaeniatus

The kinetic properties of pyruvate kinase from skeletal muscle were studied in two species of air-breathing fish, Hoplerythrinus unitaeniatus and Arapaima gigas, and two species of water-breathing fish, Hoplias malabaricus and Osteoglossum bicirrhosum. It was found that the enzymes from Hoplias and Hoplerythrinus showed hyperbolic saturation kinetics for all substrates, were activated slightly by fructose 1,6-diphosphate, and were inhibited by phosphocreatine and citrate. The enzyme from Hoplias was inhibited by alanine, whereas the enzyme from Hoplerythrinus was not. The enzymes from Arapaima and Osteoglossum showed hyperbolic saturation kinetics for adenosine diphosphate, but the saturation kinetics for phusphoenol-pyruvate were sigmoidal. These enzymes were strongly activated by fructose 1,6-diphosphate and strongly inhibited by alanine, the former completely reversing the inhibition by the latter. Phosphocreatine and citrate were also found to be inhibitors of these enzymes, but the inhibition by phosphocreatine was not reversed by additions of fructose 1,6-diphosphate. The enzymes from the water-breathing fish were more sensitive to inhibition by alanine than were those from the air-breathing fish, but in other respects the enzymes were very similar.

scholarly journals The NLRP3 inflammasome contributes to sarcopenia and lower muscle glycolytic potential in old mice

2017 ◽  
Vol 313 (2) ◽  
pp. E222-E232 ◽  
Author(s):  
Marin Jane McBride ◽  
Kevin P. Foley ◽  
Donna M. D’Souza ◽  
Yujin E. Li ◽  
Trevor C. Lau ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Strength ◽  
Nlrp3 Inflammasome ◽  
Skeletal Muscles ◽  
Metabolic Flux ◽  
Caspase 1 ◽  
Gapdh Activity ◽  
Age Related ◽  
Glycolytic Potential ◽  
Old Mice

The mechanisms underpinning decreased skeletal muscle strength and slowing of movement during aging are ill-defined. “Inflammaging,” increased inflammation with advancing age, may contribute to aspects of sarcopenia, but little is known about the participatory immune components. We discovered that aging was associated with increased caspase-1 activity in mouse skeletal muscle. We hypothesized that the caspase-1-containing NLRP3 inflammasome contributes to sarcopenia in mice. Male C57BL/6J wild-type (WT) and NLRP3−/− mice were aged to 10 (adult) and 24 mo (old). NLRP3−/− mice were protected from decreased muscle mass (relative to body mass) and decreased size of type IIB and IIA myofibers, which occurred between 10 and 24 mo of age in WT mice. Old NLRP3−/− mice also had increased relative muscle strength and endurance and were protected from age-related increases in the number of myopathic fibers. We found no evidence of age-related or NLRP3-dependent changes in markers of systemic inflammation. Increased caspase-1 activity was associated with GAPDH proteolysis and reduced GAPDH enzymatic activity in skeletal muscles from old WT mice. Aging did not alter caspase-1 activity, GAPDH proteolysis, or GAPDH activity in skeletal muscles of NLRP3−/− mice. Our results show that the NLRP3 inflammasome participates in age-related loss of muscle glycolytic potential. Deletion of NLRP3 mitigates both the decline in glycolytic myofiber size and the reduced activity of glycolytic enzymes in muscle during aging. We propose that the etiology of sarcopenia involves direct communication between immune responses and metabolic flux in skeletal muscle.

Glutamine Metabolism in Skeletal Muscle of Glucocorticoid-Treated Rats

1990 ◽  
Vol 79 (2) ◽  
pp. 139-147 ◽  
Author(s):  
M. Salleh M. Ardawi ◽  
Yasir S. Jamal
Keyword(s):  
Skeletal Muscle ◽  
Exchange Rates ◽  
Skeletal Muscles ◽  
Plasma Concentrations ◽  
Maximal Activity ◽  
Glutamine Metabolism ◽  
Dexamethasone Treatment ◽  
Concentration Difference

1. The effect of dexamethasone (30 μg day−-1 100 g−-1 body weight) on the regulation of glutamine metabolism was studied in skeletal muscles of rats after 9 days of treatment. 2. Dexamethasone resulted in negative nitrogen balance, and produced increases in the plasma concentrations of alanine (23.4%) and insulin (158%) but a decrease in the plasma concentration of glutamine (28.7%). 3. Dexamethasone treatment increased the rate of glutamine production in muscle, skin and adipose tissue preparations, with muscle production accounting for over 90% of total glutamine produced by the hindlimb. 4. Blood flow and arteriovenous concentration difference measurements across the hindlimb showed an increase in the net exchange rates of glutamine (25.3%) and alanine (90.5%) in dexamethasone-treated rats compared with corresponding controls. 5. Dexamethasone treatment produced significant decreases in the concentrations of skeletal muscle glutamine (51.8%) and 2-oxoglutarate (50.8%). The concentrations of alanine (16.2%), pyruvate (45.9%), ammonia (43.3%) and inosine 5′-phosphate (141.8%) were increased. 6. The maximal activity of glutamine synthetase was increased (21–34%), but there was no change in that of glutaminase, in muscles of dexamethasone-treated rats. 7. It is concluded that glucocorticoid administration enhances the rates of release of both glutamine and alanine from skeletal muscle of rats (both in vitro and in vivo). This may be due to changes in efflux and/or increased intracellular formation of glutamine and alanine.

A Kinetic Analysis of Rabbit Muscle Pyruvate Kinase in the Reverse Direction

1975 ◽  
Vol 3 (2) ◽  
pp. 312-314 ◽  
Author(s):  
IAN G. GILES ◽  
PETER C. POAT ◽  
KENNETH A. MUNDAY
Keyword(s):  
Kinetic Analysis ◽  
Pyruvate Kinase ◽  
Reverse Direction ◽  
Rabbit Muscle ◽  
Muscle Pyruvate Kinase

Regulatory Properties of Skeletal-Muscle Pyruvate Kinase

1977 ◽  
Vol 5 (6) ◽  
pp. 1747-1748
Author(s):  
BHANU ODEDRA ◽  
DENNIS P. BRILEY ◽  
ARTHUR W. G. COLE ◽  
T. NORMAN PALMER
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Kinase ◽  
Muscle Pyruvate Kinase ◽  
Regulatory Properties

Differential response of rat cardiac and skeletal muscle glycogen to glucocorticoids

1982 ◽  
Vol 60 (5) ◽  
pp. 634-637 ◽  
Author(s):  
James L. Poland ◽  
Jerry W. Poland ◽  
Richard N. Honey
Keyword(s):  
Skeletal Muscle ◽  
Muscle Glycogen ◽  
Skeletal Muscles ◽  
Vastus Lateralis ◽  
Experimental Period ◽  
Plasma Free Fatty Acid ◽  
Liver Glycogen ◽  
Skeletal Muscle Glycogen ◽  
Exercise Induced ◽  
Peak Value

Though glucocorticoids were previously implicated in the support of myocardial glycogen supercompensation after exercise, it was unclear why skeletal muscle glycogen did not simultaneously supercompensate since it was also exposed to the exercise-induced glucocorticoid increases. The current study shows that glucocorticoids differentially affect cardiac and skeletal muscle glycogen. Following dexamethasone administration (400 μg i.p.) myocardial glycogen peaked at 6 h while glycogen in the soleus, red vastus lateralis, and white vastus lateralis increased more slowly and reached the highest values 17 h postinjection. Concurrently, blood glucose, insulin, and glucagon remained at control levels. Liver glycogen increased within 2 h and continued to rise with a peak value at 17 h. Plasma free fatty acid (FFA) levels increased and remained high throughout the 26-h experimental period. High FFA levels inhibit glycogenolysis and thus could be partially responsible for glucocorticoid-induced glycogen increases. It is postulated that glycogen supercompensation does not readily occur in skeletal muscles after exercise because of the brevity of the corticosterone and FFA increases and the slowness of the skeletal muscle glycogen response to glucocorticoids.

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