scholarly journals IMPLICATIONS OF HYPERGLYCEMIA FOR POST-EXERCISE RESYNTHESIS OF GLYCOGEN IN TROUT SKELETAL MUSCLE

1994 ◽  
Vol 189 (1) ◽  
pp. 69-84 ◽  
Author(s):  
T West ◽  
P Schulte ◽  
P Hochachka
Keyword(s):  
Skeletal Muscle ◽  
Plasma Glucose ◽  
Muscle Glycogen ◽  
Glucose Concentration ◽  
Plasma Glucose Level ◽  
White Muscle ◽  
Glucose Utilization ◽  
Glucose Turnover ◽  
Red Muscle ◽  
Glucose Availability

Rates of whole-body glucose turnover and muscle-specific glucose utilization were determined in rainbow trout (Oncorhynchus mykiss) at rest and at intervals during recovery from burst swimming. Plasma glucose level was high in the experimental animals (range 6­38 mmol l-1), but hyperglycemia was not related specifically to exercise. Estimated glucose turnover, 19.3±2.6 (rest) and 15.8±3.9 µmol min-1 kg-1 (recovery), was also highly variable, but was linearly associated with plasma glucose concentration (turnover=0.97[glucose]+0.57, r=0.93) in both resting and recovering fish. While utilization of glucose in the whole animal was clearly responsive to plasma glucose availability, estimated total skeletal muscle disposal of glucose accounted for less than 15 % of glucose turnover, indicating that glucose was utilized largely by tissues other than locomotory muscle. Rates of glucose utilization in white muscle (range 0.5­4 nmol min-1 g-1) provide direct evidence that glucose, regardless of plasma concentration, accounted for less than 10 % of glycogen repletion during exercise recovery. In red muscle, glucose uptake was influenced by plasma glucose level below 10­12 mmol l-1 (utilization range 1­15 nmol min-1 g-1), but was independent of glucose concentration above about 12 mmol l-1 (utilization plateaued at 15­20 nmol min-1 g-1). Trout red muscle is similar to mammalian white muscle in the sense that glucose is estimated to account incompletely for glycogen restoration (25­60 %), suggesting dependence on both glycogenesis and glyconeogenesis during recovery. It is concluded that hyperglycemia may be important to the pattern of substrate incorporation into red muscle glycogen and to the rate of repletion observed, but glucose availability has, as predicted from earlier indirect studies, little relevance to white muscle glycogen restoration. The regulatory mechanisms that govern apparently very high glucose turnover rates during extreme hyperglycemia, concomitant with low disposal rates in skeletal muscle, require further investigation.

Muscle glucose utilization during sustained swimming in the carp (Cyprinus carpio)

1994 ◽  
Vol 267 (5) ◽  
pp. R1226-R1234 ◽  
Author(s):  
T. G. West ◽  
C. J. Brauner ◽  
P. W. Hochachka
Keyword(s):  
Muscle Mass ◽  
Plasma Glucose ◽  
Glucose Concentration ◽  
Glucose Utilization ◽  
Plasma Glucose Concentration ◽  
Whole Body ◽  
Control Fish ◽  
Glucose Turnover ◽  
Metabolic Clearance ◽  
Red Muscle

The involvement of circulatory glucose in the energy provision of skeletal muscle and heart of swimming carp was examined. Plasma glucose concentration varied from 3 to 17 mM among individual carp, and estimates of glucose turnover rate (RT) were positively correlated with plasma glucose level in resting fish (range 1.6-6.3 mumol.min-1.kg-1) and in swimming fish (range 4.2-10.7 mumol.min-1.kg-1). Carp that were exercised at 80% of their critical swimming speed displayed a twofold higher RT at any given plasma glucose concentration. Metabolic clearance rate also doubled in swimming carp (1.0 +/- 0.1 ml.min-1.kg-1) relative to resting controls (0.5 +/- 0.1 ml.min-1.kg-1). Indexes of muscle glucose utilization (GUI), determined with 2-deoxy-D-[14C]glucose, indicated that glucose utilization in red muscle was not dependent on plasma glucose concentration; however, glucose utilization in this muscle mass was threefold higher in swimming fish than in resting control fish. On the basis of whole body aerobic scope measurements in carp, it was estimated that circulatory glucose potentially comprised 25-30% of the total fuel oxidation in the active red muscle mass. GUI in heart was positively correlated with plasma glucose concentration, and it is possible that glucose availability had considerable influence on the pattern of myocardial substrate oxidation in resting and active carp. Carp are somewhat more reliant than rainbow trout on glucose for locomotor energetics, correlating with species differences in swimming capability and with the greater capacity of omnivorous carp to tolerate dietary glucose.

scholarly journals Role of insulin on exercise-induced GLUT-4 protein expression and glycogen supercompensation in rat skeletal muscle

2004 ◽  
Vol 96 (2) ◽  
pp. 621-627 ◽  
Author(s):  
Chia-Hua Kuo ◽  
Hyonson Hwang ◽  
Man-Cheong Lee ◽  
Arthur L. Castle ◽  
John L. Ivy
Keyword(s):  
Skeletal Muscle ◽  
Protein Expression ◽  
Muscle Glycogen ◽  
White Muscle ◽  
Insulin Response ◽  
Exercise Session ◽  
Carbohydrate Supplementation ◽  
Glut 4 ◽  
Red Muscle

The purpose of this study was to investigate the role of insulin on skeletal muscle GLUT-4 protein expression and glycogen storage after postexercise carbohydrate supplementation. Male Sprague-Dawley rats were randomly assigned to one of six treatment groups: sedentary control (Con), Con with streptozocin (Stz/C), immediately postexercise (Ex0), Ex0 with Stz (Stz/Ex0), 5-h postexercise (Ex5), and Ex5 with Stz (Stz/Ex5). Rats were exercised by swimming (2 bouts of 3 h) and carbohydrate supplemented immediately after each exercise session by glucose intubation (1 ml of a 50% wt/vol). Stz was administered 72-h before exercise, which resulted in hyperglycemia and elimination of the insulin response to the carbohydrate supplement. GLUT-4 protein of Ex0 rats was 30% above Con in fast-twitch (FT) red and 21% above Con in FT white muscle. In Ex5, GLUT-4 protein was 52% above Con in FT red and 47% above Con in FT white muscle. Muscle glycogen in FT red and white muscle was also increased above Con in Ex5 rats. Neither GLUT-4 protein nor muscle glycogen was increased above Con in Stz/Ex0 or Stz/Ex5 rats. GLUT-4 mRNA in FT red muscle of Ex0 rats was 61% above Con but only 33% above Con in Ex5 rats. GLUT-4 mRNA in FT red muscle of Stz/C and Stz/Ex0 rats was similar but significantly elevated in Ex5/Stz rats. These results suggest that insulin is essential for the increase in GLUT-4 protein expression following postexercise carbohydrate supplementation.

scholarly journals Effect of carbohydrate supplementation on postexercise GLUT-4 protein expression in skeletal muscle

1999 ◽  
Vol 87 (6) ◽  
pp. 2290-2295 ◽  
Author(s):  
Chia-Hua Kuo ◽  
Desmond G. Hunt ◽  
Zhenping Ding ◽  
John L. Ivy
Keyword(s):  
Skeletal Muscle ◽  
Protein Expression ◽  
Muscle Glycogen ◽  
Protein Concentration ◽  
Translational Efficiency ◽  
Carbohydrate Supplementation ◽  
Glut 4 ◽  
Red Muscle ◽  
Fast Twitch ◽  
Glucose Availability

The effect of carbohydrate supplementation on skeletal muscle glucose transporter GLUT-4 protein expression was studied in fast-twitch red and white gastrocnemius muscle of Sprague-Dawley rats before and after glycogen depletion by swimming. Exercise significantly reduced fast-twitch red muscle glycogen by 50%. During a 16-h exercise recovery period, muscle glycogen returned to control levels (25.0 ± 1.4 μmol/g) in exercise-fasted rats (24.2 ± 0.3 μmol/g). However, when carbohydrate supplementation was provided during and immediately postexercise by intubation, muscle glycogen increased 77% above control (44.4 ± 2.1 μmol/g). Exercise-fasting resulted in an 80% increase in fast-twitch red muscle GLUT-4 mRNA but only a 43% increase in GLUT-4 protein concentration. Conversely, exercise plus carbohydrate supplementation elevated fast-twitch red muscle GLUT-4 protein concentration by 88% above control, whereas GLUT-4 mRNA was increased by only 40%. Neither a 16-h fast nor carbohydrate supplementation had an effect on fast-twitch red muscle GLUT-4 protein concentration or on GLUT-4 mRNA in sedentary rats, although carbohydrate supplementation increased muscle glycogen concentration by 40% (35.0 ± 0.9 μmol/g). GLUT-4 protein in fast-twitch white muscle followed a pattern similar to fast-twitch red muscle. These results indicate that carbohydrate supplementation, provided with exercise, will enhance GLUT-4 protein expression by increasing translational efficiency. Conversely, postexercise fasting appears to upregulate GLUT-4 mRNA, possibly to amplify GLUT-4 protein expression on an increase in glucose availability. These regulatory mechanisms may help control muscle glucose uptake in accordance with glucose availability and protect against postexercise hypoglycemia.

Contribution of cortisol to glucose counterregulation in humans

1989 ◽  
Vol 257 (1) ◽  
pp. E35-E42 ◽  
Author(s):  
P. De Feo ◽  
G. Perriello ◽  
E. Torlone ◽  
M. M. Ventura ◽  
C. Fanelli ◽  
...  
Keyword(s):  
Plasma Glucose ◽  
Glucose Concentration ◽  
Glucose Utilization ◽  
Hepatic Glucose Production ◽  
Hormone Secretion ◽  
Glucose Production ◽  
Plasma Free Fatty Acid ◽  
Normal Subjects ◽  
Plasma Glucose Concentration ◽  
Cortisol Increase

To test the hypothesis that cortisol secretion plays a counterregulatory role in hypoglycemia in humans, four studies were performed in eight normal subjects. In all studies, insulin (15 mU.m-2.min-1) was infused subcutaneously (plasma insulin 27 +/- 1 microU/ml). In study 1, plasma glucose concentration and glucose fluxes [( 3-3H]glucose), substrate, and counterregulatory hormone concentrations were simply monitored, and plasma glucose decreased from 89 +/- 2 to 52 +/- 2 mg/dl for 12 h. In study 2, (pituitary-adrenal-pancreatic clamp), insulin and counterregulatory hormone secretion (except for catecholamines) was prevented by somatostatin (0.5 mg/h, iv) and metyrapone (0.5 g/4 h, per os), and glucagon, cortisol, and growth hormone were infused to reproduce the concentrations of study 1. In study 3 (lack of cortisol increase), the pituitary-adrenal-pancreatic clamp was performed with maintenance of plasma cortisol at basal levels, and glucose was infused, whenever needed, to reproduce plasma glucose concentration of study 2. Study 4 was identical to study 3, but exogenous glucose was not infused. Isolated lack of cortisol increase caused a approximately 22% decrease in hepatic glucose production (P less than 0.01) and a approximately 15% increase in peripheral glucose utilization (P less than 0.01), which resulted in greater hypoglycemia (37 +/- 2 vs. 52 +/- 2 mg/dl, P less than 0.01) despite compensatory increases in plasma epinephrine. Lack of cortisol response also reduced plasma free fatty acid, beta-hydroxybutyrate, and glycerol concentrations approximately 50%. We conclude that cortisol normally plays an important counterregulatory role during hypoglycemia by augmenting glucose production, decreasing glucose utilization, and accelerating lipolysis.

scholarly journals Low intrinsic running capacity is associated with reduced skeletal muscle substrate oxidation and lower mitochondrial content in white skeletal muscle

2011 ◽  
Vol 300 (4) ◽  
pp. R835-R843 ◽  
Author(s):  
Donato A. Rivas ◽  
Sarah J. Lessard ◽  
Misato Saito ◽  
Anna M. Friedhuber ◽  
Lauren G. Koch ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Aerobic Capacity ◽  
Artificial Selection ◽  
White Muscle ◽  
Metabolic Diseases ◽  
Metabolic Health ◽  
Mitochondrial Content ◽  
Red Muscle ◽  
Selection For

Chronic metabolic diseases develop from the complex interaction of environmental and genetic factors, although the extent to which each contributes to these disorders is unknown. Here, we test the hypothesis that artificial selection for low intrinsic aerobic running capacity is associated with reduced skeletal muscle metabolism and impaired metabolic health. Rat models for low- (LCR) and high- (HCR) intrinsic running capacity were derived from genetically heterogeneous N:NIH stock for 20 generations. Artificial selection produced a 530% difference in running capacity between LCR/HCR, which was associated with significant functional differences in glucose and lipid handling by skeletal muscle, as assessed by hindlimb perfusion. LCR had reduced rates of skeletal muscle glucose uptake (∼30%; P = 0.04), glucose oxidation (∼50%; P = 0.04), and lipid oxidation (∼40%; P = 0.02). Artificial selection for low aerobic capacity was also linked with reduced molecular signaling, decreased muscle glycogen, and triglyceride storage, and a lower mitochondrial content in skeletal muscle, with the most profound changes to these parameters evident in white rather than red muscle. We show that a low intrinsic aerobic running capacity confers reduced insulin sensitivity in skeletal muscle and is associated with impaired markers of metabolic health compared with high intrinsic running capacity. Furthermore, selection for high running capacity, in the absence of exercise training, endows increased skeletal muscle insulin sensitivity and oxidative capacity in specifically white muscle rather than red muscle. These data provide evidence that differences in white muscle may have a role in the divergent aerobic capacity observed in this generation of LCR/HCR.

EFFECTS OF FEEDING AND FOOD DEPRIVATION ON OXYGEN CONSUMPTION, MUSCLE PROTEIN CONCENTRATION AND ACTIVITIES OF ENERGY METABOLISM ENZYMES IN MUSCLE AND BRAIN OF SHALLOW-LIVING (SCORPAENA GUTTATA) AND DEEP-LIVING (SEBASTOLOBUS ALASCANUS) SCORPAENID FISHES

1993 ◽  
Vol 181 (1) ◽  
pp. 213-232 ◽  
Author(s):  
T. H. Yang ◽  
G. N. Somero
Keyword(s):  
Skeletal Muscle ◽  
Metabolic Rate ◽  
Food Deprivation ◽  
Enzyme Activities ◽  
Protein Concentration ◽  
White Muscle ◽  
Muscle Protein ◽  
Metabolism Enzymes ◽  
Red Muscle ◽  
Ad Libitum

The effects of feeding and fasting were examined on the deep-living short-spine thornyhead (Sebastolobus alascanus) and the confamilial shallow-living spotted scorpionfish (Scorpaena guttata) to determine whether the low metabolic rate of the deeper-living species was in part a consequence of food deprivation in its habitat. Laboratory acclimation for periods of 90–115 days under either ad libitum feeding or complete fasting did not lead to similar rates of respiration in individuals of the two species held under identical conditions. Respiration of fish fed ad libitum was 52 % (S. guttata) or 68 % (S. alascanus) higher than for fasted fish of the same species. Furthermore, the metabolic rates of freshly collected specimens of S. alascanus resembled those of laboratory-fasted fish. In white skeletal muscle, both total protein concentration and the activities of four enzymes of ATP metabolism, lactate dehydrogenase (LDH) and pyruvate kinase (PK) of glycolysis, malate dehydrogenase (MDH) and citrate synthase (CS, a citric acid cycle indicator), were lower in S. alascanus than in S. guttata. Within a species, protein concentration and activities of the four enzymes in white muscle, but not in brain, were higher in fed than in starved fish, although these differences were greater in S. alascanus than in S. guttata. During fasting, LDH and PK activity in white muscle of S. alascanus decreased much more than MDH and CS activity; decreases in enzyme activities in red muscle were smaller than those in white muscle. Activities of enzymes in white skeletal muscle of field-collected S. alascanus generally resembled those of the fasted specimens. In contrast, red muscle of field- collected S. alascanus, compared with that of either fed or starved laboratory-held specimens, had a highly glycolytic poise (high LDH and PK activities relative to MDH and CS activities), which may suggest that muscle enzyme activities in the field-collected fish reflect adaptation to the low oxygen level in its adult habitat, the oxygen minimum layer. The strong correlations found between tissue biochemical properties and respiration rate allow us to develop a predictive index for metabolic rate from simple biochemical analyses, e.g. white muscle protein content or CS activity. We conclude that the low metabolic rate of S. alascanus is due to at least four depth-related factors: reduced abundance of food, low temperature, low ambient oxygen concentration and darkness, which may select for reduced locomotory activity.

Glucose turnover in 48-hour-fasted running rats

1987 ◽  
Vol 252 (3) ◽  
pp. R587-R593 ◽  
Author(s):  
B. Sonne ◽  
K. J. Mikines ◽  
H. Galbo
Keyword(s):  
Plasma Glucose ◽  
Muscle Glycogen ◽  
Lactate Production ◽  
Glucose Production ◽  
Liver Glycogen ◽  
Glucose Turnover ◽  
Feedback Mechanisms ◽  
Glycogen Stores ◽  
Resting Muscle ◽  
Fasted Rats

In fed rats, hyperglycemia develops during exercise. This contrasts with the view based on studies of fasted human and dog that euglycemia is maintained in exercise and glucose production (Ra) controlled by feedback mechanisms. Forty-eight-hour-fasted rats (F) were compared to fed rats (C) and overnight food-restricted (FR) rats. [3-3H]- and [U-14C] glucose were infused and blood and tissue sampled. During running (21 m/min, 0% grade) Ra increased most in C and least in F and only in F did Ra not significantly exceed glucose disappearance. Plasma glucose increased more in C (3.3 mmol/l) than in FR (1.6 mmol/l) and only modestly (0.6 mmol/l) and transiently in F. Resting liver glycogen and exercise glycogenolysis were highest in C and similar in FR and F. Resting muscle glycogen and exercise glycogenolysis were highest in C and lowest in F. During running, lactate production and gluconeogenesis were higher in FR than in F. At least in rats, responses of production and plasma concentration of glucose to exercise depend on size of liver and muscle glycogen stores; glucose production matches increase in clearance better in fasted than in fed states. Probably glucose production is stimulated by “feedforward” mechanisms and “feedback” mechanisms are added if plasma glucose decreases.

Effect of sequential infusions of glucagon and epinephrine on glucose turnover in the dog.

1978 ◽  
Vol 235 (3) ◽  
pp. E287 ◽  
Author(s):  
L Saccà ◽  
R Sherwin ◽  
P Felig
Keyword(s):  
Glucose Uptake ◽  
Plasma Glucose ◽  
Glucose Utilization ◽  
Glucose Production ◽  
Conscious Dogs ◽  
Glucose Turnover ◽  
Plasma Glucagon ◽  
Conscious Dog ◽  
Glucose Clearance ◽  
Glucose Output

Conscious dogs were infused with 1) glucagon (3 ng/kg.min) alone for 120 min followed by glucagon plus epinephrine (0.1 microgram/kg.min) for 60 min and 2) epinephrine alone (150 min) followed by epinephrine plus glucagon for 90 min. Glucagon alone caused a 10--15 mg/dl rise in plasma glucose and a 45% increase in glucose production that returned to baseline by 75--120 min. After addition of epinephrine, glucose production rose again by 80%. Infusion of epinephrine alone resulted in unchanged plasma glucagon levels, a 60--70 mg/dl rise in plasma glucose, and an 80--100% rise in glucose production that returned to baseline by 60--120 min. When glucagon was added, glucose output promptly rose again by 85%. When glucagon was infused alone, there was a rise in glucose uptake, whereas, with epinephrine, glucose uptake failed to rise and glucose clearance fell by 35--50%. We conclude that 1) hepatic refractoriness to persistent elevations of glucagon or epinephrine is specific for the hormone infused; 2) epinephrine stimulates glucose production in the conscious dog in the absence of a rise in plasma glucagon; 3) the hyperglycemic response to glucagon or epinephrine is determined in part by accompanying changes in glucose utilization.

A METHODOLOGICAL STUDY IN MEASURING T3 AND T4 CONCENTRATION IN RED AND WHITE SKELETAL MUSCLE AND PLASMA OF EUTHYROID RATS

1979 ◽  
Vol 90 (1) ◽  
pp. 81-89 ◽  
Author(s):  
J. W. Janssen ◽  
C. van Hardeveld ◽  
A. A. H. Kassenaar
Keyword(s):  
Skeletal Muscle ◽  
White Muscle ◽  
Female Rats ◽  
Normal Female ◽  
Tissue Samples ◽  
Tissue Extracts ◽  
Red Muscle ◽  
The Mean ◽  
Ethanol Extracts ◽  
Altered Thyroid

ABSTRACT T3 and T4 concentrations were determined in plasma and red and white skeletal muscle of the rat. Because of the small tissue samples (± 300 mg), the ultra-sensitive Wick radioimmunoassay (RIA) for serum was adapted for determination in ethanol extracts. The dilution curves of the plasma and tissue extracts showed excellent parallelism with the standard curves for both T3 and T4. The mean T4 level found in female rats (n = 6) was 22.6 ± 5.2 ng/ml in plasma and did not differ significantly between red (1.85 ± 0.28 ng/g) and white (1.90 ± 0.25 ng/g) skeletal muscle. The mean T3 level in 11 normal female rats was 0.629 ± 0.098 ng/ml in the plasma and was significantly higher in the red muscle (2.07 ± 0.26 ng/g) than in the white muscle (1.65 ± 0.20 ng/g). The higher T3 levels found in the red muscle as compared with the white muscle may help to elucidate the different responsiveness of these muscle types observed in altered thyroid states.

Turnover of Plasma Glucose and Free Fatty Acids in Patients on the First Day after Myocardial Infarction

1976 ◽  
Vol 50 (5) ◽  
pp. 401-407
Author(s):  
I. A. Nimmo ◽  
R. H. Smith ◽  
M. A. Dolder ◽  
M. F. Oliver
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Fatty Acids ◽  
Free Fatty Acids ◽  
Myocardial Ischaemia ◽  
Plasma Glucose ◽  
Glucose Concentration ◽  
Plasma Concentrations ◽  
Acute Episode ◽  
Glucose Turnover

1. The turnover of plasma glucose and free fatty acids was measured in ten patients within 24 h of the onset of symptoms of acute myocardial infarction and in two with symptoms of acute myocardial ischaemia. The measurements were repeated in seven of the patients 12–40 weeks after the acute episode. 2. Both for the patients with acute myocardial infarction alone and for all the individuals studied the turnover of glucose increased with plasma glucose concentration but was not related to the turnover of free fatty acids or the plasma concentrations of free fatty acids, insulin or total catecholamines. There was no obvious difference in the nature of the glucose turnover—concentration relationship between the patients with acute myocardial infarction, with acute myocardial ischaemia and on re-examination. 3. For all the individuals studied the turnover of free fatty acids increased with the concentration of these but was not related to the turnover of glucose or the plasma concentrations of glucose, insulin or total catecholamines. There was no obvious difference in the nature of the free fatty acids turnover—concentration relationship between the patients with acute myocardial infarction, with acute myocardial ischaemia and on re-examination.

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