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Results 251 - 300 of 769
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Evans M K - - 2001
This study investigated whether increased muscle acetylcarnitine provision (acetate infusion) or hyperoxia (100% O(2)) would increase the rate of oxidative phosphorylation and reduce the reliance on muscle substrate phosphorylation after the onset of moderate exercise. Eight subjects completed three randomized trials, each separated by 1 wk: 1) saline infusion for ...
Hellsten Y - - 2001
Seven males performed two exhaustive cycling bouts (EX1 and EX2) at a work-rate of 90% of maximal oxygen uptake, separated by 60 min. During EX1 there was a significant accumulation of urate (from 0.16 +/- 0.02 to 0.27 +/- 0.03 micromol/kg d.w.) and allantoin (from 0.39 +/- 0.05 to 0.69 ...
Steensberg A - - 2001
1. Prolonged exercise results in a progressive decline in glycogen content and a concomitant increase in the release of the cytokine interleukin-6 (IL-6) from contracting muscle. This study tests the hypothesis that the exercise-induced IL-6 release from contracting muscle is linked to the intramuscular glycogen availability. 2. Seven men performed ...
Tarnopolsky M A - - 2001
During submaximal endurance exercise, women oxidize more lipid and less carbohydrate as metabolic substrates than men. This is reflected in a lower glycogen utilization in skeletal muscle and lower hepatic glucose production for women compared with men. These latter observations may explain the lower leucine oxidation observed during endurance exercise ...
Rush J W - - 2001
This study aimed to determine physiologically relevant kinetic and allosteric effects of P(i), AMP, ADP, and caffeine on isolated skeletal muscle glycogen phosphorylase a (Phos a). In the absence of effectors, Phos a had Vmax = 221 +/- 2 U/mg and Km = 5.6 +/- 0.3 mM P(i) at 30 ...
Keller C - - 2001
In humans, the plasma interleukin 6 (IL-6) concentration increases dramatically during low-intensity exercise. Measurements across the working limb indicate that skeletal muscle is the source of IL-6 production. To determine whether energy availability influences the regulation of IL-6 expression during prolonged exercise, six male subjects completed two trials consisting of ...
Lacombe V A - - 2001
The purpose of this study was to determine the effect of muscle glycogen depletion and subsequent replenishment on anaerobic capacity of horses. In a blinded crossover study, seven fit horses performed glycogen-depleting exercise on two occasions. Horses were infused after glycogen-depleting exercise with either 6 g/kg body wt of glucose ...
Bruce C R - - 2001
We determined the effect of an acute bout of swimming (8 x 30 min) followed by either carbohydrate administration (0.5 mg/g glucose ip and ad libitum access to chow; CHO) or fasting (Fast) on postexercise glycogen resynthesis in soleus muscle and liver from female lean (ZL) and obese insulin-resistant (ZO) ...
Rennie M J - - 2001
After exhaustive exercise, intravenous or oral glutamine promoted skeletal muscle glycogen storage. However, when glutamine was ingested with glucose polymer, whole-body carbohydrate storage was elevated, the most likely site being liver and not muscle, possibly due to increased glucosamine formation. The rate of tricarboxylic acid (TCA) cycle flux and hence ...
DiMauro S - - 2001
There are 11 hereditary disorders of glycogen metabolism affecting muscle alone or together with other tissues, and they cause two main clinical syndromes: episodic, recurrent exercise intolerance with cramps, myalgia, and myoglobinuria; or fixed, often progressive weakness. Great strides have been made in our understanding of the molecular bases of ...
Jiao Y - - 2001
It was recently reported that MnSO4 stimulates glycogen synthase-dependent glucose transfer from UDPglucose into trichloroacetic acid precipitable endogenous glycoproteins (GSMn(T)) in human muscle extracts. To determine the physiologic significance of this reaction, we compared a new GS activity ratio, GSMn(T)/GSH(E) (where GSH(E) represents the usual glucose transfer to ethanol precipitable ...
Paton K R - - 2001
When stimulated, the ammocoetes (larvae) of Geotria australis swim continuously at a moderate rate for only approximately 20 min, whereas the downstream migrants (young adults) of this species did not become exhausted following similar swimming activity over the same period. Mean concentrations of muscle glycogen in ammocoetes declined during exercise, ...
Tarnopolsky M A - - 2001
1. Myoadenylate deaminase (AMPD) deficiency is present in 1--2 % of the population. In theory, this deficiency may alter exercise energy metabolism by impairing the purine nucleotide cycle (PNC) and reducing tricarboxylic acid (TCA) cycle anaplerosis. The role of the PNC in TCA cycle anaplerosis is still a debated issue ...
Bak H - - 2001
Muscle-specific phosphorylase b kinase deficiency is an unusual form of glycogen storage disorder. The majority of patients are male with an age at diagnosis between 15 to 36 years. Clinical features include exercise intolerance, myalgia and muscle weakness. A forearm ischaemic exercise test is usually normal and histochemical staining for ...
Christmass M A - - 2001
The role of work period duration as the principal factor influencing carbohydrate metabolism during intermittent exercise has been investigated. Fuel oxidation rates and muscle glycogen and free carnitine content were compared between two protocols of sustained intermittent intense exercise with identical treadmill speed and total work duration. In the first ...
Clemmesen J O - - 2001
OBJECTIVE: In acute liver failure (ALF), urea production is severely impaired, and detoxification of ammonia by glutamine synthesis plays an important protective role. The aim of this study was to examine the effects of therapeutic high-volume plasmapheresis (HVP) on arterial concentrations and splanchnic exchange rates of ammonia, urea, and amino ...
Bruce M - - 2001
The aims of the present study were twofold: first to investigate whether TCA cycle intermediate (TCAI) pool expansion at the onset of moderate-intensity exercise in human skeletal muscle could be enhanced independently of pyruvate availability by ingestion of glutamine or ornithine alpha-ketoglutarate, and second, if it was, whether this modification ...
Okada M - - 2001
The effect of exercise on vitamin B6 metabolism and PLP-dependent enzymes was studied in rats fed a diet with or without vitamin B6. Metabolism of some amino acids (citrulline, arginine, ornithine and threonine) inhibited in the B6-deficient rats was normalized during exercise. Exercise was also effective in storing vitamin B6 ...
Tarnopolsky M A - - 2001
We have previously demonstrated that females oxidize more lipid and less protein and carbohydrate during endurance exercise [21]. Several studies in male rats have demonstrated similar metabolic changes after 4 d of 17-beta-estradiol (E2) administration. Our purpose was to study the effects of E2 administration upon substrate metabolism during 90min ...
Wilkie M P - - 2001
Although the majority of the sea lamprey's (Petromyzon marinus) life cycle is spent as a burrow-dwelling larva, or ammocoete, surprisingly little is known about intermediary metabolism in this stage of the lamprey's life history. In this study, larval sea lampreys (ammocoetes) were vigorously exercised for 5 min, and their patterns ...
Ooi Foong Kiew FK - - 2001
It is essential to replace fluids lost so as to remain well hydrated during exercise. The intake of fluids is considered a physiological ergogenic aid to enhance exercise performance. There are currently several products in the market that are believed to have ergogenic properties which act as fluid replacement drinks ...
Shearer J - - 2001
This study examined the relationship between preexercise muscle glycogen content and glycogen utilization in two physiological pools, pro- (PG) and macroglycogen (MG). Male subjects (n = 6) completed an exercise and dietary protocol before the experiment that resulted in one leg with high glycogen (HL) and one with low glycogen ...
Wojtaszewski J F - - 2001
Studies of skeletal muscle from rodents performed both in vivo and in vitro suggest a regulatory role of glycogen synthase kinase (GSK) 3 in glycogen synthase (GS) activation in response to insulin. Recently, hyperinsulinemic clamp studies in humans support such a role under nearly physiological conditions. In addition, in rats ...
Ferreira L D - - 2001
It has recently been shown that food intake is not essential for the resynthesis of the stores of muscle glycogen in fasted animals recovering from high-intensity exercise. Because the effect of diabetes on this process has never been examined before, we undertook to explore this issue. To this end, groups ...
Kiens B - - 2001
For many years athletes have used carbohydrate loading to enhance endurance performance. This practice has been based on findings demonstrating that 1) exercise induced depletion of the muscle glycogen stores followed by the intake of a carbohydrate rich diet, resulted in muscle glycogen stores above normal values and 2) that ...
Ivy J L - - 2001
Muscle glycogen is an essential fuel for prolonged intense exercise, and therefore it is important that the glycogen stores be copious for competition and strenuous training regimens. While early research focused on means of increasing the muscle glycogen stores in preparation for competition and its day-to-day replenishment, recent research has ...
Décombaz J - - 2000
BACKGROUND: Muscle triglycerides are important as a source of energy and in relation to metabolic sensitivity. However, the classic biopsy method does not distinguish intra- from extracellular fat, and their regulation by exercise and diet is largely unknown. Magnetic resonance spectroscopy (MRS) is available to assess the intramyocellular lipid (IMCL) ...
Rotman S - - 2000
The rate of glycogen resynthesis in human skeletal muscle after glycogen-depleting exercise is known to depend on carbohydrate intake and is reported to reach a plateau after an adequate amount of carbohydrate (CHO) consumption. Efforts to maximize the rate of glycogen storage by changing the type and form of CHO, ...
Goedecke J H - - 2000
We examined the variability and determinants of the respiratory exchange ratio (RER) at rest and during exercise in 61 trained cyclists. Fasting (10-12 h) RER was measured at rest and during exercise at 25, 50, and 70% of peak power output (W(peak)), during which blood samples were drawn for [lactate] ...
Odland L M - - 2000
This study examined the effects of elevated free fatty acid (FFA) provision on the regulation of pyruvate dehydrogenase (PDH) activity and malonyl-CoA (M-CoA) content in human skeletal muscle during moderate-intensity exercise. Seven men rested for 30 min and cycled for 10 min at 40% and 10 min at 65% of ...
Bélanger P - - 2000
The purpose of the present study was to test the hypothesis that a higher hepatic glycogen level is associated with higher glucagon-induced hepatic glycogen depletion. Four groups of anesthetized rats received three injections (at times 0, 30, and 60 min) of glucagon (intravenously, 20 [microg/kg). Among these groups, hepatic glycogen ...
Kjaer M - - 2000
The role of adrenaline in regulating muscle glycogenolysis and hormone-sensitive lipase (HSL) activity during exercise was examined in six adrenaline-deficient bilaterally adrenalectomised, adrenocortico-hormonal-substituted humans (Adr) and in six healthy control individuals (Con). Subjects cycled for 45 min at approximately 70% maximal pulmonary O2 uptake (VO2,max) followed by 15 min at ...
Kristiansen S - - 2000
Endurance training increases muscle content of glucose transporter proteins (GLUT-4) but decreases glucose utilization during exercise at a given absolute submaximal intensity. We hypothesized that glucose uptake might be higher in trained vs. untrained muscle during heavy exercise in the glycogen-depleted state. Eight untrained subjects endurance trained one thigh for ...
St Amand T A - - 2000
The effects of carbohydrate deprivation on the regulation of pyruvate dehydrogenase (PDH) were studied at rest and during moderate-intensity exercise. An inhibitory effect of a chronic low-carbohydrate diet (LCD) on the active form of PDH (PDHa) mediated by a stable increase in PDH kinase (PDHK) activity has recently been reported ...
van Loon L J - - 2000
BACKGROUND: Postexercise muscle glycogen synthesis is an important factor in determining the time needed to recover from prolonged exercise. OBJECTIVE: This study investigated whether an increase in carbohydrate intake, ingestion of a mixture of protein hydrolysate and amino acids in combination with carbohydrate, or both results in higher postexercise muscle ...
Kemme M J - - 2000
OBJECTIVES: Recombinant tissue factor pathway inhibitor (rTFPI) has been shown to be an effective treatment in animal models of sepsis and is under investigation for human use. Reduced liver blood flow during septic shock may substantially alter the pharmacokinetics of rTFPI because clearance of rTFPI approaches liver blood flow. The ...
Piehl Aulin K - - 2000
The rate of muscle glycogen synthesis during 2 and 4 h of recovery after depletion by exercise was studied using two energy equivalent carbohydrate drinks, one containing a polyglucoside with a mean molecular mass of 500 000-700 000 (C drink), and one containing monomers and oligomers of glucose with a ...
Hargreaves M - - 2000
1. Contracting skeletal muscle is able to use a number of intra- and extramuscular substrates to generate ATP during exercise. These include creatine phosphate (CP), muscle glycogen, blood-borne glucose, lactate and free fatty acids (FFA), derived from either adipose tissue or intramuscular triglyceride stores. 2. During high-intensity short-duration exercise, CP ...
Straczkowski M - - 2000
The aim of the present study was to estimate whether a single bout of exhaustive exercise influences the glycogen and triglyceride (TG) content in red and white gastrocnemius muscle and in the liver of rats with experimental type 2 diabetes. Experiments were carried out on male Wistar rats fed from ...
Price T B - - 2000
This study compared muscle glycogen recovery after depletion of approximately 50 mmol/l (DeltaGly) from normal (Nor) resting levels (63.2 +/- 2.8 mmol/l) with recovery after depletion of approximately 50 mmol/l from a glycogen-loaded (GL) state (99.3 +/- 4.0 mmol/l) in 12 healthy, untrained subjects (5 men, 7 women). To glycogen ...
Casey A - - 2000
This study investigated the effect of carbohydrate (CHO) ingestion on postexercise glycogen resynthesis, measured simultaneously in liver and muscle (n = 6) by (13)C magnetic resonance spectroscopy, and subsequent exercise capacity (n = 10). Subjects cycled at 70% maximal oxygen uptake for 83 +/- 8 min on six separate occasions. ...
Miura A - - 2000
For high-intensity cycle ergometer exercise, the relation between power (P) and its tolerable duration (t) has been well characterized by the hyperbolic relationship: (P-thetaF) t = W', or P = W' (1/t)+thetaF, where thetaF may be termed the 'fatigue threshold'. The curvature constant (W') reflects a constant amount of work ...
Mazepa R C - - 2000
The effects of melatonin on several parameters of carbohydrate and lipid metabolism were investigated in exercised and nonexercised rats. Animals were run to exhaustion on a rodent treadmill at 24 m/min and a 12% slope. Exercise resulted in a significant hypoglycemia and increased plasma levels of lactate and beta-hydroxybutyrate, together ...
Conlee R K - - 2000
In our previous work, we routinely observed that a combined cocaine-exercise challenge results in an abnormally rapid muscle glycogen depletion and excessive blood lactacidosis. These phenomena occur simultaneously with a rapid rise in norepinephrine and in the absence of any rise in epinephrine. We postulated that norepinephrine may cause vasoconstriction ...
Bissonnette B - - 1999
BACKGROUND: Deep hypothermia has been associated with an increased incidence of postoperative neurologic dysfunction after cardiac surgery in children. Recent studies suggest an excitotoxic mechanism involving overstimulation of glutamate receptors. Extracellular glutamate uptake occurs primarily by astrocytes. Astrocytes also store glycogen, which may be used to sustain the energy-consuming glutamate ...
Haub M D - - 1999
We investigated the effects of carbohydrate ingestion on glycogen replenishment and subsequent short duration, high intensity exercise performance. During Session 1, aerobic power was determined and each subject (N = 6) was familiarized with the 100-kJ cycling test (100KJ-Test). During the treatment sessions, the subjects performed a 100KJ-Test (Ride-1), then ...
Febbraio M A - - 1999
A depletion of phosphocreatine (PCr), fall in the total adenine nucleotide pool (TAN = ATP + ADP + AMP), and increase in TAN degradation products inosine 5'-monophosphate (IMP) and hypoxanthine are observed at fatigue during prolonged exercise at 70% maximal O(2) uptake in untrained subjects [J. Baldwin, R. J. Snow, ...
Mancini D - - 1999
OBJECTIVES: The objective of the study was to investigate the impact of alteration of glycogen stores and metabolism on exercise performance in patients with heart failure. BACKGROUND: In normal subjects, muscle glycogen depletion results in increased exertional fatigue and reduced endurance. Skeletal muscle biopsies have revealed reduced glycogen content in ...
Parolin M L - - 1999
The time course for the activation of glycogen phosphorylase (Phos) and pyruvate dehydrogenase (PDH) and their allosteric regulators was determined in human skeletal muscle during repeated bouts of maximal exercise. Six subjects completed three 30-s bouts of maximal isokinetic cycling separated by 4-min recovery periods. Muscle biopsies were taken at ...
Van Hall G - - 1999
The aim of this study was to investigate whether prolonged one-leg knee-extensor exercise enhances net protein degradation in muscle with a normal or low glycogen content. Net amino acid production, as a measure of net protein degradation, was estimated from leg exchange and from changes in the concentrations of amino ...
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