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Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In biotin-deficient rats, a decreased intestinal transport of Na+, H2O and L-phenylalanine, and no transport differences of 3-O-methyl-D-glucose were observed. The lower Na+ and L-phenylalanine transport appears to be referable to a decreased energy availability and probably not to the lack of a carrier.
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PMID:Transport of sodium, water, 3-O-methyl-glucose and L-phenylalanine in vitro in biotin-deficient rats intestine. 89 71

Effects of an infusion of Na2HPO4 on diaphragm strength, endurance, and magnitude of recovery were evaluated in in situ canine diaphragm strips. Results showed no effect on maximal isometric tetanic tension. Twitch tension and tension in the low- (10-Hz) frequency range were significantly increased (P less than 0.01). Time to fatigue (endurance) increased by 38 +/- 4.5% in the group that received phosphorus compared with its control and decreased by 18.5 +/- 2.5% in the group that received dextrose compared with its control (P less than 0.005). Recovery from fatigue was also significantly improved after the phosphorus infusion. Serum ATP and 2,3-diphosphoglycerate levels were unchanged throughout the experiment. The results of this study support the notion that hyperphosphatemia improves diaphragmatic endurance and recovery from fatigue. The mechanisms involved may in part be due to the phosphate-buffering effects, which limit the extent of the muscle intracellular acidosis produced with fatigue.
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PMID:Effects of hyperphosphatemia on diaphragmatic strength and endurance. 150 3

The effects of up to 4 months dietary supplementation with 40% galactose on muscle and nerve function were examined in rats. Galactitol, a polyol pathway metabolite, accumulated to high levels in both tissues. This led to changes similar to those found in experimental diabetes, which were largely prevented by treatment with an inhibitor of the first enzyme in the pathway, aldose reductase. For fast twitch extensor digitorum longus muscle there was weight loss, fibre damage, slowing of twitch time to peak, increased twitch tension, and reduced tetanic tension. There were no relaxation deficits. For slow twitch soleus there were no changes in tension production. However, contraction and relaxation for both twitch and tetanus were prolonged. Fatigue resistance was reduced after 1 week. Damage in soleus led to a reduction in mean fibre area after 2 months, which largely recovered by 4 months. There was a selective loss of fast oxidative glycolytic fibres. Histochemical staining for succinic dehydrogenase was normal in galactosaemic soleus, in contrast to the marked reduction seen in diabetes. Sciatic nerve conduction velocity was reduced after 2 months, particularly in normally fast conducting motor and sensory fibres. Resistance to hypoxic conduction block was increased in galactosaemic nerves to diabetic levels. It was concluded that polyol pathway hyperactivity is likely to contribute to the aetiology of diabetic myopathy and neuropathy, and that experimental galactosaemia provides a good model in which to study pathway effects without the complicated hormonal changes found in diabetes.
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PMID:Muscle and nerve dysfunction in rats with experimental galactosaemia. 153 21

The effect of preexercise muscle glycogen content on the metabolic responses to exercise has been investigated. Seven men cycled at a work load calculated to elicit 75% of maximal oxygen uptake [211 +/- 17 (SE) W] on two occasions: 1) to fatigue (37.2 +/- 5.3 min) and 2) at the same work load and for the same duration as the first. Biopsies were obtained from the quadriceps femoris muscle before and after exercise. Before the first experiment, muscle glycogen was lowered by exercise and diet, and before the second experiment, muscle glycogen was elevated. In the low-glycogen condition (LG), muscle glycogen decreased from 182 +/- 15 at rest to 7 +/- 4 mmol glucosyl units/kg dry wt at fatigue, while in the high-glycogen condition (HG), glycogen decreased from 725 +/- 31 at rest to 353 +/- 53 mmol glucosyl units/kg dry wt at the end of exercise. Hexose monophosphates were not increased after LG exercise but increased approximately fivefold after HG exercise. Lactate increased more during HG exercise (LG = 16 +/- 5, HG = 61 +/- 7 mmol/kg dry wt; P less than or equal to 0.001), whereas IMP increased more during LG (LG = 2.8 +/- 0.6, HG = 0.9 +/- 0.2 mmol/kg dry wt; P less than or equal to 0.05). The increases in the sum of tricarboxylic acid cycle intermediates (TCAI; citrate+malate+fumarate) and acetylcarnitine (which is in equilibrium with acetyl CoA) were significantly greater during HG exercise (P less than or equal to 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of low glycogen on carbohydrate and energy metabolism in human muscle during exercise. 156 23

The internal space of the antheridium in Chara vulgaris L. is filled with the PAS-positive mucilage which is of pectic nature. Morphometric and cytophotometric measurements on the semithin sections indicate that the concentration and amount of PAS-positive polysaccharides: 1) increase during the time of antheridial growth accompanying the phase of antheridial filament divisions, 2) these parameters have the maximum after spermatid formation and at the beginning of their differentiation, i.e. spermiogenesis, 3) both concentration and amount of this substance decrease at the end of spermiogenesis. A decrease in mucilage concentration is also observed in the young antheridia after 3 days of continuous darkness. The results suggest that PAS-positive mucilagenous material is a nutritive substance, accumulated in the first phase of antheridial development and utilized mainly in spermiogenesis. These substances may also be used up in the young antheridia during the lack of energy supply. The autoradiographic studies with the use of a 3H-glucose and 3H-galactose mixture seem to confirm these suggestions.
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PMID:Cytochemical studies on the antheridial mucilage and changes in its concentration and amount during the spermatogenesis in Chara vulgaris L. 179 40

The effect of bicycle exercise (75% of maximal oxygen uptake) on glucose uptake by the inferior limb (LGU) and glycolysis in human skeletal muscle has been investigated. Biopsies were obtained from the quadriceps femoris muscle before exercise, after 5 and 40 min of exercise, and at fatigue [74.9 +/- 4.7 (SE) min]. LGU was 0.05 +/- 0.02 mmol/min at rest, increased approximately sevenfold after 5 min of exercise, and continued to increase linearly during the first 40 min of exercise. Thereafter LGU stabilized at approximately 1.4 mmol/min until fatigue. Intracellular glucose was low at rest but increased sixfold after 5 min of exercise (P less than 0.01 vs. rest); thereafter, intracellular glucose decreased and was not significantly different from the value at rest after 40 min or at fatigue (P greater than 0.05). D-Glucose 6-phosphate (G-6-P) and alpha-D-glucose 1,6-bisphosphate (G-1,6-P2) (inhibitors of hexokinase) increased significantly after 5 min of exercise (approximately 300% G-6-P; approximately 25% G-1,6-P2) and then decreased continuously. The muscle glycolytic rate (glycogenolysis + glucose uptake) averaged 7.7 mmol.kg dry wt-1.min-1 during the first 40 min of exercise and 3.7 mmol.kg dry wt-1.min-1 during the last 35 min of exercise. The contribution of extracellular glucose to muscle glycolysis was estimated to be only 5 and 19% during the initial and latter phases of exercise, respectively. It is concluded that, during the initial phase of exercise, glucose utilization is limited by phosphorylation, probably due to G-6-P-dependent inhibition of hexokinase.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of glucose utilization in human skeletal muscle during moderate dynamic exercise. 200 94

The reduced maximal exercise capacity of patients with heart failure has been attributed to skeletal muscle underperfusion with resultant intramuscular lactic acidosis and muscular fatigue. To investigate this hypothesis, the effect of dichloroacetate, a drug that decreases lactate formation by increasing pyruvate oxidation, on the maximal exercise performance of 18 patients with heart failure and reduced ejection fraction (25 +/- 9%) was examined. Exercise tests after parenteral dextrose (control) and dichloroacetate were performed 1 week apart. The sequence of interventions was randomized in a double-blind manner. Dichloroacetate decreased blood lactate at rest (control 8.0 +/- 2.5 versus dichloroacetate 5.6 +/- 2.9 mg/dl), throughout exercise and at peak exercise (control 26.0 +/- 14.3 versus dichloroacetate 19.4 +/- 10.8) (all p less than 0.05). In contrast, dichloroacetate had no effect on exercise time (control 15.2 +/- 6.0 versus dichloroacetate 15.9 +/- 6.2 min) or peak exercise oxygen consumption (control 1,280 +/- 498 ml/min versus dichloroacetate 1,312 +/- 530 ml/min) (both p = NS). In six subjects, dichloroacetate also had no effect at peak exercise on leg blood flow (control 2.8 +/- 1.1 versus dichloroacetate 3.0 +/- 0.6 liters/min) or femoral oxygen vein saturation (control 12.7 +/- 4.1% versus dichloroacetate 12.5 +/- 5.7%). These data suggest that intramuscular lactate accumulation is not responsible for muscular fatigue during exercise in patients with heart failure.
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PMID:Effect of dichloroacetate on the exercise performance of patients with heart failure. 319 43

Adult male fatty and lean rats of Zucker strain were given access ad libitum to either a single nutritionally complete diet, or a self-selection regime with separate sources of three macronutrients, protein (casein), fat (hydrogenated coconut oil), and carbohydrate (sucrose). Animals on the single diet were fed on a powdered stock diet, and then switched to the self-selection regime. Energy intake on the self-selection regime was the same as that for the single diet condition in both fatty and lean rats. Fatty rats consumed 45% more energy than did their lean littermates. Further, fatty rats selected 47.0% of their total calories as protein, 30.1% as fat, and 22.9% as carbohydrate. The respective percentages for lean rats were 56.1, 13.0 and 30.9. In lean rats, the injection of insulin (10 U/kg) or 2-deoxy-D-glucose (500 mg/kg, 2DG) failed to increase energy intake, but increased carbohydrate intake 2 times by attenuating protein intake. Also in fatty rats, insulin did not increase energy intake, but it did increase carbohydrate by 50% by attenuating fat intake. 2DG decreased energy intake by attenuating carbohydrate and fat intakes in fatty rats. Fatty rats were slightly less hypoglycemic to insulin, but more hyperglycemic to 2DG than lean rats. These different self-selection patterns of fatty rats seemed to be associated with their endocrine, metabolic, and behavioral abnormalities.
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PMID:Feeding in response to insulin and 2-deoxy-D-glucose in Zucker rats on dietary self-selection. 638 68

The results of a retrospective analysis of 59 patients with Gilbert's syndrome are presented. All the patients were selected on the basis of repeatedly documented, predominantly unconjugated hyperbilirubinemia in the absence of liver or hemolytic disease. The peak incidence of Gilbert's syndrome was in the 15-30 years age group with males predominating almost fivefold. Scleral icterus or a laboratory finding of hyperbilirubinemia represented the major reasons for workup. Presenting symptoms such as fatigue, upper abdominal pain and fat intolerance were largely nonspecific. Whereas minimal values for total serum bilirubin concentrations were, at l.57 +/- 0.56 mg/dl (mean +/- S.D.), often within the normal range (less than 1.2), maximal values were always clearly elevated (2.05 +/- 0.65). The sex difference in bilirubin levels was also maintained in the Gilbert's syndrome, since mean values in women were lower than in men. As expected, neither liver scan nor histology yielded evidence of structural abnormalities. The results of liver function studies such as galactose elimination capacity, aminopyrine breath test, or fasting and postprandial serum bile acids, were all within normal limits. In contrast, the initial plasma disappearance of bromsulphthalein (BSP-k1) was reduced in 6 patients to a mean of 8.7% per min (normal value 12.6 +/- 1.6), which suggests that these subjects belong to the Gilbert type with diminished hepatic clearance of anionic dyes. The hematological investigations, including hemoglobin electrophoresis, Coombs tests and erythrocyte enzymes, yielded normal results. However, osmotic fragility was increased in 5 cases and erythrocyte survival reduced to less than 24 days in 9 cases (of 17 investigated). In 35 patients, a nicotinic acid test was performed in which total serum bilirubin rose within 3 hours from a mean of 1.66 +/- 0.7 to 3.51 +/- 0.75 mg/dl. Between the third and fifth hour bilirubin levels plateaued, yielding retention values of 98%, 92% and 92% respectively. These retention values may be considered in indirect estimate of bilirubin clearance. Retentions exceeding 70% after 5 hours correspond to bilirubin clearances of less than 20 ml/min, representing evidence in favour of the diagnosis of Gilbert's syndrome.
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PMID:[Positive diagnosis of Gilbert syndrome. Retrospective analysis of 59 cases with special reference to the nicotinic acid test]. 713 40

This study examined the effect of lesions of dopamine (DA) nerve terminals the medial prefrontal cortex on local cerebral glucose utilization (LCGU) and dopamine metabolism in the rat brain. Bilateral 6-hydroxydopamine lesions were stereotaxically placed in the medial prefrontal cortex. Twenty-eight days after the lesion, concentrations of DA and its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), were determined in eight brain regions with a high-performance liquid chromatographic assay. LCGU was assessed by [14C]2-deoxy-D-glucose autoradiography. The lesion produced a striking reduction in DA (to 6% of the control value), and a moderate reduction in DOPAC and HVA in the medial prefrontal cortex. The ratio of DOPAC to DA in the medial prefrontal cortex was significantly elevated in the 6-OHDA lesioned animals. In contrast to DA depletion, LCGU in the medial prefrontal cortex of the lesioned rats was unaltered when compared with the control. These findings suggest that decreased energy metabolism in the frontal cortex, i.e., hypofrontality, does not occur with decreased DA innervation of that site.
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PMID:Hypofrontality does not occur with 6-hydroxydopamine lesions of the medial prefrontal cortex in rat brain. 754 53


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