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

The anti-fatigue effect of 50% ethanol extract ([M]) from the dried whole body of Agkistrodon blomhoffii blomhoffii Boie, was investigated using an acute weight-loaded forced swimming (AWLFS) test by monitoring swimming times, blood biochemical parameters, thiobarbiturate-reactive substances (TBARS) as an index of lipid peroxide and antioxidative enzyme activities in blood and tissue. [M] (500 mg/kg/d), given orally for three successive days, significantly prolonged swimming times. It also inhibited the elevation of TBARS in plasma, liver, brain, kidney and soleus, and inhibited the lowering of catalase activity in erythrocyte, liver and soleus. However, it had no inhibitory effect on the elevation of creatine-kinase activity, free fatty acid and lactic acid levels or on the decrease in glucose level in serum. Also, it decreased the plasma TBARS level and increased the superoxide dismutase activity of plasma and erythrocytes in normal rats. From these results, it can be considered that [M] has an anti-fatigue effect.
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PMID:Pharmacological study on Agkistrodon blomhoffii blomhoffii BOIE. V. anti-fatigue effect of the 50% ethanol extract in acute weight-loaded forced swimming-treated rats. 882 Sep 13

In four experiments, semantic satiation was investigated in young and old adults. In the first two experiments, subjects were repeatedly presented a word (e.g., DOG) and then were presented a pair of words (e.g., DOG-CAT or DOG-CHAIR) for a relatedness decision. The results of both experiments indicated that for the young adults, the relatedness effect (the difference between response latency on related and unrelated trials) decreased as a function of the number of times the satiated word was repeated, whereas for the older adults, there was no evidence of a decrease in the relatedness effect across repetitions of the satiated word. In the third experiment, we investigated whether phonological codes are also susceptible to satiation. This experiment was similar to the first two experiments with the exception that subjects made rhyme decisions (SAME-CLAIM VS. SAME-DIME) instead of semantic relatedness decisions. The results of this experiment did not yield any evidence of satiation for either the young adults or the older adults. The final experiment eliminated a simple decrease in attentional alertness or fatigue account of the semantic satiation effects found in the first two experiments. In this experiment, the repeated word was always unrelated to the pair of words presented for the relatedness decision. The results of this experiment did not yield any evidence of semantic satiation for either the young or the older adults. The discussion focuses on the mechanisms underlying semantic satiation and the implications of age-related changes in these mechanisms.
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PMID:Semantic satiation in healthy young and older adults. 909 71

Little is known about the antioxidant capacity and oxidant-generating potential of newborn muscle, or how these properties compare with the adult and relate to fatigue resistance. We determined the 1) antioxidant enzyme activities [superoxide dismutase (SOD), catalase, glutathione peroxidase], 2) glutathione content, 3) oxidative capacity [indexed by succinic dehydrogenase activity], 4) extracellular cytochrome c reduction, and 5) efficacy of exogenously administered SOD in ameliorating fatigue in vitro of newborn and adult diaphragm (DIA). Newborn and adult DIA SOD activities were not different, whereas newborn catalase activity was greater, and newborn glutathione peroxidase activity and glutathione content less than adult DIA. Succinic dehydrogenase activity was approximately 2-fold greater in the adult compared with the neonate. Repetitive contractions led to a significant decline in newborn and adult DIA force; this decline was greater in the adult (78 +/- 4% decrement in force at 2 min) compared with newborn DIA (28 +/- 8% decrement in force at 2 min). Extracellular cytochrome c reduction was greater in adult as compared with newborn DIA during fatiguing contractions. Exogenous SOD attenuated fatigue in the adult, but had no effect on newborn DIA. We conclude that the oxidative capacity of the adult DIA is greater than that of the newborn and not matched by a concomitant increase in SOD activity. Our data suggest that the increased oxidative capacity relative to SOD activity in adult DIA may lead to oxidative stress and an enhanced susceptibility to fatigue.
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PMID:Rat diaphragm oxidative capacity, antioxidant enzymes, and fatigue: newborn versus adult. 921 38

The paper deals with the history of development of one of the basic trends in scientific activity of Academician O. V. Palladin and world-known biochemical school created by him: biochemistry and physiology of muscular activity. Retrospective analysis of the works by O. V. Palladin and his pupils, dedicated to the mentioned problem permits judging of realization of his ideas, when studying the process of training, work to fatigue by means of determining the content of energy sources in muscles (creatine, creatine phosphoric acid, carnosine cholesterin, glycogen), some redox enzymes (catalase, dehydrogenases), lactic acid, vitamins (ascorbic acid, B1). It is emphasized that the scientific legacy of O. V. Palladin's school is of great practical importance for rational substantiation of regimes of physical loads of sportsmen and physical culture men, production sphere workers. The works of this school have exerted considerable influence on the solution of labour physiology problem.
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PMID:[Research of Academician O.V. Palladin and his school in the field of biochemistry and physiology of muscles]. 922 45

Acidosis during exercise has long been associated with skeletal muscle fatigue. Recent evidence also has linked reactive oxygen species (ROS) with fatigue in skeletal muscle, including the diaphragm. We hypothesized that acidosis (designed to mimic blood pH during maximal exercise) would worsen ROS-induced depression of diaphragm contractility. The xanthine oxidase (XO) reaction in solution (0.01 U/ml) allows direct assessment of the effects of oxidant stress by ROS. Costal diaphragm fiber bundles from 24 Sprague-Dawley rats (200-250 g) were divided into four treatment groups: 1) pH 7.4, no XO (H); 2) pH 7.4 + XO (HXO); 3) pH 7.0, no XO (L); and 4) pH 7.0 + XO (LXO). Baseline twitch mechanics and force-frequency relationships (Pre) were determined in control Krebs solution (pH 7.4, no XO) before treatment. Treatment solutions were introduced, and the diaphragm underwent 2 min of contractions at 25 Hz (250 ms) at a rate of 1/s. After 10 min of recovery, the control solution was reintroduced into the bath and postcontractile function (Post) was measured. Significant reductions in twitch tension and low-frequency tetanic tension were greater in HXO and LXO compared with H, without an effect on maximal tetanic tension. One-half relaxation time was prolonged only by the combination of acidosis and oxidative stress. Addition of superoxide dismutase (50 U/ml) worsened and catalase (1,800 U/ml) attenuated XO-induced depression of diaphragm contractility. We concluded that XO induced a reduction of low-frequency tension in the fatigued diaphragm, which was mediated directly or indirectly through hydrogen peroxide and was exacerbated to a modest extent with acidosis.
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PMID:Effect of oxidative stress and acidosis on diaphragm contractile function. 927 48

Bile accumulation in the peritoneal cavity after partial hepatectomy reduces hepatic regeneration. In 70% of hepatectomized rats with bile peritonitis, hepatic DNA synthesis showed a delayed initiation and diminished peak level. Because intraperitoneal bile significantly accelerated lipid peroxidation and decreased energy metabolism in the liver remnant, all hepatectomized rats with bile peritonitis died within 7 days. Subcutaneous administration of exogenous combined antioxidants SOD and catalase dramatically reduced lipid peroxidation and improved the survival rate. Although the slightly elevated serum endotoxin level in rats with peritonitis may play a role in the inhibition of hepatic regeneration, the result suggest that intraperitoneal accumulation of bile components may also directly accelerate lipid peroxidation in the liver remnant, inhibiting the hepatic regeneration.
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PMID:The degree of hepatic regeneration after partial hepatectomy in rats with peritonitis and the role of lipid peroxidation. 1023 31

Muscular exercise results in an increased production of radicals and other forms of reactive oxygen species. Further more, growing evidence implicates cytotoxic ROS as an underlying cause in exercise-induced disturbances in muscle redox status that could result in muscle fatigue or injury. Muscle cells contain complex cellular defense mechanisms to minimize the risk for oxidative injury. Two major classes of endogenous protective mechanisms work together to reduce the harmful effects of oxidants in the cell: (1) enzymatic and (2) nonenzymatic antioxidants. Key antioxidant enzymes include superoxide dismutase, glutathione peroxidase, and catalase. These enzymes are responsible for removing superoxide radicals, hydrogen peroxide or organic hydroperoxides, and hydrogen peroxide, respectively. Important nonenzymatic antioxidants include vitamins E and C, beta-carotene, GSH, uric acid, ubiquinone, and bilirubin. Vitamin E, beta-carotene, and ubiquinone are located in lipid regions of the cell, whereas uric acid, GSH, and bilirubin are in aqueous compartments of the cell. Although numerous animal experiments have demonstrated that the addition of antioxidants can improve muscular performance, to date, limited evidence shows that dietary supplementation with antioxidants improves human performance. This is an important area for future research.
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PMID:Antioxidants and exercise. 1041 Aug 39

Cellular oxidants include a variety of reactive oxygen, nitrogen, and chlorinating species. It is well established that the increase in metabolic rate in skeletal muscle during contractile activity results in an increased production of oxidants. Failure to remove these oxidants during exercise can result in significant oxidative damage of cellular biomolecules. Fortunately, regular endurance exercise results in adaptations in the skeletal muscle antioxidant capacity, which protects myocytes against the deleterious effects of oxidants and prevents extensive cellular damage. This review discusses the effects of chronic exercise on the up-regulation of both antioxidant enzymes and the glutathione antioxidant defense system. Primary antioxidant enzymes superoxide dismutase, glutathione peroxidase, and catalase will be discussed as well as glutathione, which is an important nonenzymatic antioxidant. Growing evidence indicates that exercise training results in an elevation in the activities of both superoxide dismutase and glutathione peroxidase along with increased cellular concentrations of glutathione in skeletal muscles. It seems plausible that increased cellular concentrations of these antioxidants will reduce the risk of cellular injury, improve performance, and delay muscle fatigue.
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PMID:Exercise training-induced alterations in skeletal muscle antioxidant capacity: a brief review. 1041 60

The suggested role of oxidative stress in the pathogenesis of heart failure is largely based on utilizing left heart failure models. The present study on rats evaluated changes in antioxidants as well as oxidative stress in relation to hemodynamic function subsequent to the right heart failure induced by monocrotaline (50 mg/kg, i.p.). During the post-injection period, monocrotaline (MCT)-treated rats demonstrated a persistent growth depression. Two to three weeks after the injection, MCT-treated rats showed signs of fatigue, peripheral cyanosis and dyspnea. In these rats, right heart hypertrophy was confirmed by a significant increase in right ventricular weight as well as right ventricle to body weight ratio. In MCT-treated rats, there was also a significant increase in right ventricular systolic as well as end diastolic pressures. No change in lung and liver wet/dry weight ratios between MCT-treated and control animals was observed. Based on the hemodynamic data as well as other clinical observations, the functional stage achieved was compensated heart failure. Myocardial antioxidant enzymes, catalase, glutathione peroxidase and superoxide dismutase, in the MCT-treated rats were not different compared to control rats. Vitamin E levels were significantly depressed in the RV and there was no change in retinol levels. There was a significant increase in lipid hydroperoxide concentrations in MCT-treated rats as compared to the control group. These data provide evidence that right heart failure is associated with an increase in oxidative stress.
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PMID:Myocardial oxidative stress changes during compensated right heart failure in rats. 1044 2

These experiments tested the hypothesis that short-term endurance exercise training would rapidly improve (within 5 days) the diaphragm oxidative/antioxidant capacity and protect the diaphragm against contraction-induced oxidative stress. To test this postulate, male Sprague-Dawley rats (6 weeks old) ran on a motorized treadmill for 5 consecutive days (40-60 min x day(-1)) at approximately 65% maximal oxygen uptake. Costal diaphragm strips were excised from both sedentary control (CON, n=14) and trained (TR, n=13) animals 24 h after the last exercise session, for measurement of in vitro contraction properties and selected biochemical parameters of oxidative/antioxidant capacity. Training did not alter diaphragm force-frequency characteristics over a full range of submaximal and maximal stimulation frequencies (P > 0.05). In contrast, training improved diaphragm resistance to fatigue as contraction forces were better-maintained by the diaphragms of the TR animals during a submaximal 60-min fatigue protocol (P < 0.05). Following the fatigue protocol, diaphragm strips from the TR animals contained 30% lower concentrations of lipid hydroperoxides compared to CON (P < 0.05). Biochemical analysis revealed that exercise training increased diaphragm oxidative and antioxidant capacity (citrate synthase activity +18%, catalase activity +24%, total superoxide dismutase activity +20%, glutathione concentration +10%) (P < 0.05). These data indicate that short-term exercise training can rapidly elevate oxidative capacity as well as enzymatic and non-enzymatic antioxidant defenses in the diaphragm. Furthermore, this up-regulation in antioxidant defenses would be accompanied by a reduction in contraction-induced lipid peroxidation and an increased fatigue resistance.
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PMID:Short-term exercise training improves diaphragm antioxidant capacity and endurance. 1055 69


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