Single fiber analyses of glycogen-related proteins reveal their differential association with glycogen in rat skeletal muscle

2012 ◽  
Vol 303 (11) ◽  
pp. C1146-C1155 ◽  
Author(s):  
Robyn M. Murphy ◽  
Hongyang Xu ◽  
Heidy Latchman ◽  
Noni T. Larkins ◽  
Paul R. Gooley ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Fiber Type ◽  
Glycogen Synthesis ◽  
Glycogen Metabolism ◽  
Muscle Physiology ◽  
Rat Skeletal Muscle ◽  
Muscle Glycogen Synthesis ◽  
Triton X ◽  
Fast Twitch

To understand how glycogen affects skeletal muscle physiology, we examined enzymes essential for muscle glycogen synthesis and degradation using single fibers from quiescent and stimulated rat skeletal muscle. Presenting a shift in paradigm, we show these proteins are differentially associated with glycogen granules. Protein diffusibility and/or abundance of glycogenin, glycogen branching enzyme (GBE), debranching enzyme (GDE), phosphorylase (GP), and synthase (GS) were examined in fibers isolated from rat fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus (SOL) muscle. GDE and GP proteins were more abundant (∼10- to 100-fold) in fibers from EDL compared with SOL muscle. GS and glycogenin proteins were similar between muscles while GBE had an approximately fourfold greater abundance in SOL muscle. Mechanically skinned fibers exposed to physiological buffer for 10 min showed ∼70% total pools of GBE and GP were diffusible (nonbound), whereas GDE and GS were considerably less diffusible. Intense in vitro stimulation, sufficient to elicit a ∼50% decrease in intracellular glycogen, increased diffusibility of GDE, GP, and GS (∼15–60%) and decreased GBE diffusibility (∼20%). Amylase treatment, which breaks α-1,4 linkages of glycogen, indicated differential diffusibilities and hence glycogen associations of GDE and GS. Membrane solubilization (1% Triton-X-100) allowed a small additional amount of GDE and GS to diffuse from fibers, suggesting the majority of nonglycogen-associated GDE/GS is associated with myofibrillar/contractile network of muscle rather than membranes. Given differences in enzymes required for glycogen metabolism, the current findings suggest glycogen particles have fiber-type-dependent structures. The greater catabolic potential of glycogen breakdown in fast-twitch fibers may account for different contraction induced rates of glycogen utilization.

scholarly journals ProNGF/p75NTR Axis Drives Fiber Type Specification by Inducing the Fast-Glycolytic Phenotype in Mouse Skeletal Muscle Cells

Cells ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 2232
Author(s):  
Valentina Pallottini ◽  
Mayra Colardo ◽  
Claudia Tonini ◽  
Noemi Martella ◽  
Georgios Strimpakos ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Myogenic Differentiation ◽  
Fiber Type ◽  
Pcr Analysis ◽  
Mdx Mouse ◽  
Mdx Mice ◽  
Muscle Physiology

Despite its undisputable role in the homeostatic regulation of the nervous system, the nerve growth factor (NGF) also governs the relevant cellular processes in other tissues and organs. In this study, we aimed at assessing the expression and the putative involvement of NGF signaling in skeletal muscle physiology. To reach this objective, we employed satellite cell-derived myoblasts as an in vitro culture model. In vivo experiments were performed on Tibialis anterior from wild-type mice and an mdx mouse model of Duchenne muscular dystrophy. Targets of interest were mainly assessed by means of morphological, Western blot and qRT-PCR analysis. The results show that proNGF is involved in myogenic differentiation. Importantly, the proNGF/p75NTR pathway orchestrates a slow-to-fast fiber type transition by counteracting the expression of slow myosin heavy chain and that of oxidative markers. Concurrently, proNGF/p75NTR activation facilitates the induction of fast myosin heavy chain and of fast/glycolytic markers. Furthermore, we also provided evidence that the oxidative metabolism is impaired in mdx mice, and that these alterations are paralleled by a prominent buildup of proNGF and p75NTR. These findings underline that the proNGF/p75NTR pathway may play a crucial role in fiber type determination and suggest its prospective modulation as an innovative therapeutic approach to counteract muscle disorders.

scholarly journals The effect of insulin-like growth factor II on glucose uptake and metabolism in rat skeletal muscle in vitro

1992 ◽  
Vol 286 (2) ◽  
pp. 561-565 ◽  
Author(s):  
S J Bevan ◽  
M Parry-Billings ◽  
E Opara ◽  
C T Liu ◽  
D B Dunger ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Growth Factor ◽  
Glucose Uptake ◽  
Glycogen Synthesis ◽  
Insulin Like Growth Factor ◽  
Rat Skeletal Muscle ◽  
Factor Ii ◽  
Igf Binding ◽  
Uptake And Metabolism

The effect of insulin-like growth factor II (IGF II) on the rates of lactate formation, glycogen synthesis and glucose transport in the presence of a range of concentrations of insulin were investigated using an isolated preparation of rat skeletal muscle. IGF II, at a concentration of 65 ng/ml, caused a small but significant increase in the rates of these processes at a basal physiological insulin concentration (10 muunits/ml), but was without effect in the presence of 1, 100, 1000 or 10,000 muunits of insulin/ml. Hence IGF II increased the insulin sensitivity of this tissue. This effect was removed if the incubation medium was supplemented with an equimolar concentration of IGF binding protein 1 (BP1). It is suggested that changes in the concentration of IGF II and/or BP1 may regulate glucose uptake and metabolism in skeletal muscle and have physiological significance in the control of blood glucose level.

Diet-induced obesity and acute hyperlipidemia reduce IκBα levels in rat skeletal muscle in a fiber-type dependent manner

2006 ◽  
Vol 290 (1) ◽  
pp. R233-R240 ◽  
Author(s):  
Bankim A. Bhatt ◽  
John J. Dube ◽  
Nikolas Dedousis ◽  
Jodie A. Reider ◽  
Robert M. O’Doherty
Keyword(s):  
Skeletal Muscle ◽  
P38 Mapk ◽  
Fiber Type ◽  
Dependent Manner ◽  
Rat Skeletal Muscle ◽  
Diet Induced Obesity ◽  
Slow Twitch ◽  
Fast Twitch ◽  
Fat Feeding ◽  
Increased Activity

Increased activity of proinflammatory/stress pathways has been implicated in the pathogenesis of insulin resistance in obesity. However, the effects of obesity on the activity of these pathways in skeletal muscle, the major insulin-sensitive tissue by mass, are poorly understood. Furthermore, the mechanisms that activate proinflammatory/stress pathways in obesity are unknown. The present study addressed the effects of diet-induced obesity (DIO; 6 wk of high-fat feeding) and acute (6-h) hyperlipidemia (HL) in rats on activity of IKK/IκB/NF-κB c-Jun NH2-terminal kinase, and p38 MAPK in three skeletal muscles differing in fiber type [superficial vastus (Vas; fast twitch-glycolytic), soleus (Sol; slow twitch-oxidative), and gastrocnemius (Gas; mixed)]. DIO decreased the levels of the IκBα in Vas (24 ± 3%, P = 0.001, n = 8) but not in Sol or Gas compared with standard chow-fed controls. Similar to DIO, HL decreased IκBα levels in Vas (26 ± 5%, P = 0.006, n = 6) and in Gas (15 ± 4%, P = 0.01, n = 7) but not in Sol compared with saline-infused controls. Importantly, the fiber-type-dependent effects on IκBα levels could not be explained by differential accumulation of triglyceride in Sol and Vas. HL, but not DIO, decreased phospho-p38 MAPK levels in Vas (41 ± 7% P = 0.004, n = 6) but not in Sol or Gas. Finally, skeletal muscle c-Jun NH2-terminal kinase activity was unchanged by DIO or HL. We conclude that diet-induced obesity and acute HL reduce IκBα levels in rat skeletal muscle in a fiber-type-dependent manner.

Carnitine delays rat skeletal muscle fatigue in vitro

1993 ◽  
Vol 75 (4) ◽  
pp. 1595-1600 ◽  
Author(s):  
E. P. Brass ◽  
A. M. Scarrow ◽  
L. J. Ruff ◽  
K. A. Masterson ◽  
E. Van Lunteren
Keyword(s):  
Skeletal Muscle ◽  
Soleus Muscle ◽  
Fiber Type ◽  
Type I ◽  
Glycogen Depletion ◽  
Rat Skeletal Muscle ◽  
Skeletal Muscle Function ◽  
Total Carnitine ◽  
Initial Force

Carnitine has been used to enhance human exercise performance. To test the hypothesis that carnitine can directly modify skeletal muscle function, fatigue of isolated rat skeletal muscle strips was studied in vitro. Carnitine (10 mM) did not modify the initial force of soleus contraction. The time over which force declined by 50% during repetitive electrical stimulation of the soleus muscle (fiber type I) was prolonged 25% in the presence of 10 mM carnitine. In contrast, carnitine had no effect on the fatigue of extensor digitorum longus muscle strips (fiber type II). The beneficial effect of carnitine on soleus muscle strips was not observed if the routine 30-min preincubation in the presence of carnitine was decreased to 5 min; it was associated with a five- to sixfold increase in muscle total carnitine content and a 50#x2013;150% increase in muscle long-chain acylcarnitine content. Carnitine did not consistently modify lactate accumulation or glycogen depletion during the fatigue protocol. Incubation with propionyl-L-carnitine resulted in a decreased initial force of contraction and a delay in reaching maximal contractile force. Thus, carnitine can directly improve the fatigue characteristics of muscles enriched in type I fibers.

Effect of catecholamines on glucose uptake and glycogenolysis in rat skeletal muscle

1985 ◽  
Vol 248 (5) ◽  
pp. C406-C409 ◽  
Author(s):  
D. A. Young ◽  
H. Wallberg-Henriksson ◽  
J. Cranshaw ◽  
M. Chen ◽  
J. O. Holloszy
Keyword(s):  
Skeletal Muscle ◽  
Sugar Transport ◽  
Beta Agonist ◽  
Sugar Uptake ◽  
Rat Skeletal Muscle ◽  
Adrenergic Control ◽  
Slow Twitch ◽  
Fast Twitch ◽  
Alpha Agonist

The effect of catecholamines on glycogenolysis and sugar transport was evaluated in rat epitrochlearis (fast-twitch) and soleus (slow-twitch) muscles in vitro. When muscles were incubated with 0.1 microM epinephrine (both an alpha- and beta-agonist), the proportion of phosphorylase in the a form increased from 6.2 +/- 0.7 to 37.4 +/- 5.7% in epitrochlearis muscle and from 9.1 +/- 0.7 to 21.6 +/- 1.3% in soleus muscle. Both the activation of phosphorylase and the resulting glycogenolysis could be prevented by preincubation with the beta-blocker, propranolol. The effect of catecholamines on the rate of sugar transport was also examined in epitrochlearis muscle. The beta-agonist, isoproterenol, significantly depressed the rate of 3-O-methylglucose uptake, while the alpha-agonist, phenylephrine, had no effect. Inclusion of 0.1% albumin in the incubation medium increased the resting rate of sugar transport twofold. When isoproterenol + albumin were present, rather than exerting a depressive effect the catecholamine further increased the rate of sugar uptake. This increase was prevented by preincubation with propranolol. It was concluded that glycogenolysis and sugar transport in rat skeletal muscle are solely under beta-adrenergic control.

Na+-K+-ATPase in rat skeletal muscle: muscle fiber-specific differences in exercise-induced changes in ion affinity and maximal activity

2009 ◽  
Vol 296 (1) ◽  
pp. R125-R132 ◽  
Author(s):  
Carsten Juel
Keyword(s):  
Skeletal Muscle ◽  
Atpase Activity ◽  
Muscle Fiber ◽  
Muscle Activity ◽  
Fiber Type ◽  
Treadmill Running ◽  
Vitro Activity ◽  
In Vitro Activity ◽  
Rat Skeletal Muscle

It is unclear whether muscle activity reduces or increases Na+-K+-ATPase maximal in vitro activity in rat skeletal muscle, and it is not known whether muscle activity changes the Na+-K+-ATPase ion affinity. The present study uses quantification of ATP hydrolysis to characterize muscle fiber type-specific changes in Na+-K+-ATPase activity in sarcolemmal membranes and in total membranes obtained from control rats and after 30 min of treadmill running. ATPase activity was measured at Na+ concentrations of 0–80 mM and K+ concentrations of 0–10 mM. Km and Vmax values were obtained from a Hill plot. Km for Na+ was higher (lower affinity) in total membranes of glycolytic muscle (extensor digitorum longus and white vastus lateralis), when compared with oxidative muscle (red gastrocnemius and soleus). Treadmill running induced a significant decrease in Km for Na+ in total membranes of glycolytic muscle, which abolished the fiber-type difference in Na+ affinity. Km for K+ (in the presence of Na+) was not influenced by running. Running only increased the maximal in vitro activity ( Vmax) in total membranes from soleus, whereas Vmax remained constant in the three other muscles tested. In conclusion, muscle activity induces fiber type-specific changes both in Na+ affinity and maximal in vitro activity of the Na+-K+-ATPase. The underlying mechanisms may involve translocation of subunits and increased association between PLM units and the αβ complex. The changes in Na+-K+-ATPase ion affinity are expected to influence muscle ion balance during muscle contraction.

scholarly journals Effects of insulin-like growth factor I on the rates of glucose transport and utilization in rat skeletal muscle in vitro

1992 ◽  
Vol 285 (1) ◽  
pp. 269-274 ◽  
Author(s):  
G Dimitriadis ◽  
M Parry-Billings ◽  
S Bevan ◽  
D Dunger ◽  
T Piva ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Growth Factor ◽  
Glucose Transport ◽  
Glycogen Synthesis ◽  
Insulin Like Growth Factor ◽  
Rat Skeletal Muscle ◽  
Factor I ◽  
Igf I ◽  
Lactate Formation

1. The effects of insulin-like growth factor I (IGF-I) on the rates of glucose transport and utilization and its interaction with insulin were investigated in rat soleus muscle in vitro. IGF-I increased the rates of glucose transport, lactate formation, glycogen synthesis and the flux of glucose to hexose monophosphate, but it had no effect on the rate of glucose oxidation or glycogenolysis. 2. In the absence of insulin, low levels of IGF-I (0-30 ng/ml) increased the rate of glycolysis and the content of fructose 2,6-bisphosphate, but the content of glucose 6-phosphate remained unaltered; at higher levels of IGF-I (300-3000 ng/ml) the rate of glycolysis and the content of fructose 2,6-bisphosphate showed a further modest increase, but the content of glucose 6-phosphate doubled. Similar changes were seen when the level of insulin was increased from basal (0-0.4 ng/ml) to maximal (40 ng/ml). 3. Neither IGF-I nor insulin affected the contents of ATP, ADP, AMP, phosphocreatine or citrate. 4. Maximal concentrations of IGF-I increased the rate of lactate formation to a greater extent than did maximal concentrations of insulin. 5. In the presence of IGF-I, the rate of glucose utilization was less responsive to insulin. 6. The results suggest that, in rat skeletal muscle: (a) IGF-I increases the rates of glucose transport and utilization independently of insulin, and has a preferential effect on the rate of lactate formation; (b) the effects of IGF-I and insulin are not additive; (c) in addition to its effects on glucose transport, IGF-I increases the rate of glycogen synthesis and may stimulate glycolysis at the level of 6-phosphofructokinase; (d) changes in the content of fructose 2,6-bisphosphate may be part of the mechanism to regulate glycolytic flux in skeletal muscle in response to either IGF-I or insulin.

Diaphragm arterioles are less responsive to α1- adrenergic constriction than gastrocnemius arterioles

2002 ◽  
Vol 92 (5) ◽  
pp. 1808-1816 ◽  
Author(s):  
Aaron Aaker ◽  
M. H. Laughlin
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Gastrocnemius Muscle ◽  
Fiber Type ◽  
Muscle Blood Flow ◽  
Oxidative Capacity ◽  
Receptor Stimulation ◽  
Exercise Induced ◽  
Fast Twitch

The sympathetic nervous system has greater influence on vascular resistance in low-oxidative, fast-twitch skeletal muscle than in high-oxidative skeletal muscle (17). The purpose of this study was to test the hypothesis that arterioles isolated from low-oxidative, fast-twitch skeletal muscle [the white portion of gastrocnemius (WG)] possess greater responsiveness to adrenergic constriction than arterioles isolated from high-oxidative skeletal muscle [red portion of the gastrocnemius muscle (RG) and diaphragm (Dia)]. Second-order arterioles (2As) were isolated from WG, RG, and Dia of rats and reactivity examined in vitro. Results reveal that Dia 2As constrict less to norepinephrine (NE) (10−9 to 10 −4 M) than 2As from RG and WG, which exhibited similar NE-induced constrictions. This difference was not endothelium dependent, because responses of denuded 2As were similar to those of intact arterioles. The blunted NE-induced constrictor response of Dia 2As appears to be the result of differences in α1-receptor effects because 1) arterioles from Dia also responded less to selective α1-receptor stimulation with phenylephrine than RG and WG arterioles; 2) arterioles from Dia, RG, and WG dilated similarly to isoproterenol (10−9 to 10−4 M) and did not respond to selective α2-receptor stimulation with UK-14304; and 3) endothelin-1 produced similar constriction in 2As from Dia, RG, and WG. We conclude that differences in oxidative capacity and/or fiber type composition of muscle tissue do not explain different NE responsiveness of Dia 2As compared with 2As from gastrocnemius muscle. Differences in α1-adrenergic constrictor responsiveness among arterioles in skeletal muscle may contribute to nonuniform muscle blood flow responses observed during exercise and serve to maintain blood flow to Dia during exercise-induced increases in sympathetic nerve activity.

Insulin binding and sensitivity in rat skeletal muscle: effect of starvation

1981 ◽  
Vol 240 (2) ◽  
pp. E184-E190 ◽  
Author(s):  
L. J. Brady ◽  
M. N. Goodman ◽  
F. N. Kalish ◽  
N. B. Ruderman
Keyword(s):  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Glucose Metabolism ◽  
Glucose Uptake ◽  
Glycogen Synthesis ◽  
Insulin Binding ◽  
The Other ◽  
Rat Skeletal Muscle ◽  
In Vitro Sensitivity

In contrast to adipose tissue and heart, the in vitro sensitivity of skeletal muscle to insulin is enhanced by starvation. To determine the basis for this, insulin binding and its ability to stimulate glucose metabolism were examined in the incubated rat soleus. In solei from 50-g rats, starvation for 48 h enhanced insulin binding by 50-100% at concentrations of 100 ng/ml or less. Starvation also resulted in higher basal and insulin-stimulated rates of glycogen synthesis, glycolysis, and glucose uptake. The enhanced effect of insulin only occurred at concentrations less than 50-75 ng/ml, in keeping with the increased binding of insulin in this concentration range. On the other hand, under conditions in which binding at equilibrium was the same, glucose uptake was still higher in the starved group, suggesting that some postreceptor event may have been more sensitive to insulin. These studies confirm that the in vitro sensitivity of rat skeletal muscle to insulin is enhanced by 48 h of starvation. They suggest that this is due at least partially to an increase in insulin binding at physiological concentrations.

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