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

Leg muscles of adult rats were stimulated chronically at a low-frequency, and the histochemical reactions of various enzymes (succinic dehydrogenase, mitochondrial alpha-glycerophosphate dehydrogenase, phosphorylase, alkali-ATPase and acid-ATPase), capillary density, resistance to fatigue, and contractile properties were studied. Following stimulation, the histochemical properties of muscle fibres in the fast extensor digitorum longus (EDL) and tibialis anterior (TA) muscles became similar to those of the majority of fibres in the slow soleus muscle. In the soleus muscle, the histochemical properties of the few fast type fibres became similar to the majority of 'slow' fibres so that its fibre composition was homogeneously 'slow'. The stimulated fast muscles also had higher capillary density and were more resistant to fatigue than normal. Despite the prolonged stimulation, the twitch duration of the fast muscles was little changed. This result differs from the findings obtained previously for the rabbit and cat, which show that slowing of contraction can be achieved by low-frequency activity of similar duration. Thus it may be that there is a species difference regarding the readiness with which the transformation of fast to slow muscles can be brought about.
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PMID:Effects of low-frequency electrical stimulation on fast and slow muscles of the rat. 621 64

Transversal sections of the inferior oblique muscle from kittens of various ages and from adult cats were stained for myofibrillar ATP-ase at Ph 9.4 and 4.35, succinic dehydrogenase (SDH) and fat. The same muscles had previously been submitted to studies of contractional and fatigue properties. With ATPase the fibers could be differentiated into types I, II and II C. The percentages of each fiber type remained approximately the same from birth onwards. In the inner, global layer of the muscle, type I fibers showed a linear increase in size, but types II and IIC fibers an accelerated growth after age 20 weeks. In the outer, orbital layer, where no type I fibers were seen, type II and II C fibers showed the same growth pattern as in the global layer. The fiber content of SHD and fat was low at birth but increased after two weeks of age. Type I fibers were poor and type II C fibers rich in SDH and fat. Type II fibers showed varying amounts of these substances. Provided that type I fibers are slow, type II fast and type II C intermediate in speed of contraction, like in other muscles, the findings on fiber growth and SDH content seem to support the idea that slow, fatigue resistant components in eye muscles reach maturity earlier than fast components.
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PMID:The postnatal development of the inferior oblique muscle of the cat. III. Fiber sizes and histochemical properties. 644 74

Lizard skeletal muscle fiber types were investigated in the iliofibularis (IF) muscle of the desert iguana (Dipsosaurus dorsalis). Three fiber types were identified based on histochemical staining for myosin ATPase (mATPase), succinic dehydrogenase (SDH), and alphaglycerophosphate dehydrogenase (alphaGPDH) activity. The pale region of the IF contains exclusively fast-twitch-glycolytic (FG) fibers, which stain dark for mATPase and alphaGPDH, light SDH. The red region of the IF contains fast-twitch-oxidative-glycolytic (FOG) fibers, which stain dark for all three enzymes, and tonic fibers, which stain light for mATPase, dark for SDH, and moderate for alphaGPDH. Enzymatic activities of myofibrillar ATPase, citrate synthase, and alphaGPDH confirm these histochemical interpretations. Lizard FG and FOG fibers possess twitch contraction times and resistance to fatigue comparable to analogous fibers in mammals, but are one-half as oxidative and several times as glycolytic as analogous fibers in rats. Lizard tonic fibers demonstrate the acetylcholine sensitivity common to other vertebrate tonic fibers.
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PMID:Histochemical, enzymatic, and contractile properties of skeletal muscle fibers in the lizard Dipsosaurus dorsalis. 645 26

By means of histological method and ultrasound cardiographic (UCG) examination, the left-right ratio of transectional area of muscle fiber of latissimus dorsi muscle (LDM) after non-dynamic cardiomyoplasty was 77.4 +/- 11.7% in Group I (3 weeks after operation), and 78.4 +/- 11.6% atrophy and hyperplasia of LDM, but the basical structure was retained. The ejection fraction (EF) decreased significantly after operation (P < 0.05), but the difference between two groups was non- significant. Also, dynamic cardiomyoplasty was performed on a sheep. UCG showed the increased cardiac systolic function after operation. ATPase, succinodehydrogenase (SDH) and PAS examination implied the strengthening of fatigue-resistant ability in skeletal muscles after long-term electrical stimulation. So cardiomyoplasty is suggested to be a supplementary measure in treating end-stage heart failure.
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PMID:Cardiac function and histological changes after non-dynamic cardiomyoplasty and preliminary study of dynamic cardiomyoplasty. 786 91

We correlated the fatigue resistance (FR) of the costal diaphragm (DIA) and external abdominal oblique (EAO) of the rat during postnatal development with their respective 1) myosin heavy chain (MHC) phenotypes and 2) oxidative capacities [indexed by quantitative measurements of succinic dehydrogenase (SDH) enzyme activity]. FR was measured in vitro during isometric contractions with the use of the Burke fatigue test. FR of the DIA and EAO was high in newborns and declined during postnatal development. SDH activity was uniformly low in neonatal DIA and EAO and increased during early postnatal development before declining to adult levels. FR did not significantly correlate with SDH activity (r2 = 0.01) but did relate to the MHC phenotype as indexed by the ratio of adult MHC isoform content (slow + IIa + IIx + IIb) to developmental MHC isoform content (slow + neonatal; r2 = 0.88, P < 0.01). Stepwise regression revealed that neonatal MHC expression alone accounted for 60% of the developmental variance in FR. The correlation between FR and MHC phenotype was improved if SDH was also considered, i.e., the ratio of SDH to MHC phenotype (r2 = 0.99, P < 0.01). We conclude that FR of respiratory muscle during development relates to a balance between the energetic demands of the muscle contractile proteins as reflected by MHC isoform composition and its oxidative capacity with MHC phenotype alone exerting a strong predictive effect on FR.
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PMID:Respiratory muscle fatigue resistance relates to myosin phenotype and SDH activity during development. 822 49

This study examined the effect of inhibition of aldose reductase, the first enzyme in the polyol pathway, on fast and slow twitch skeletal muscle morphology and function in streptozotocin-induced diabetes in rats. There was a preventative investigation with diabetes duration of 4 months, and a reversal investigation where treatment was given for 2 months following an untreated period of 2 months. For slow twitch soleus muscle, contractions were prolonged by diabetes, and this was partially prevented but not reversed by treatment. Relaxation was profoundly slowed, and both prevention and reversal ameliorated the changes. Diabetes had minimal effects on tension production for soleus. However, for fast twitch extensor digitorum longus, although there was little effect on speed-related contractile parameters, tetanic tension production was progressively reduced with diabetes duration. This effect was antagonized by treatment. Soleus fatigue resistance was markedly reduced by diabetes, but restored to normal by treatment. There was a reduction in oxidative enzyme staining (succinic dehydrogenase), and capillary-fibre ratio, both of which were ameliorated by aldose reductase inhibition. Mean soleus fibre area was reduced after 4 months of diabetes, and this was prevented but not reversed by treatment. Fibre area was also reduced in extensor digitorum longus, particularly for fast glycolytic fibres. There was a small amelioration with treatment. It is concluded that enhanced polyol pathway activity makes a contribution to diabetic myopathy, and that aldose reductase inhibitors can prevent this by actions on muscle fibres and their vascular supply.
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PMID:Polyol pathway-related skeletal muscle contractile and morphological abnormalities in diabetic rats. 847 Dec 37

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

This study examined functional, biochemical, and morphological characteristics of skeletal muscle in nine multiple sclerosis (MS) patients and eight healthy controls in an effort to ascertain whether intramuscular adaptations could account for excessive fatigue in this disease. Analyses of biopsies of the tibialis anterior muscle showed that there were fewer type I fibers (66 +/- 6 vs. 76 +/- 6%), and that fibers of all types were smaller (average downward arrow26%) and had lower succinic dehydrogenase (SDH; average downward arrow40%) and SDH/alpha-glycerol-phosphate dehydrogenase (GPDH) but not GPDH activities in MS vs. control subjects, suggesting that muscle in this disease is smaller and relies more on anaerobic than aerobic-oxidative energy supply than does muscle of healthy individuals. Maximal voluntary isometric force for dorsiflexion was associated with both average fiber cross-sectional area (r = 0.71, P = 0.005) and muscle fat-free cross-sectional area by magnetic resonance imaging (r = 0.80, P < 0. 001). Physical activity, assessed by accelerometer, was associated with average fiber SDH/GPDH (r = 0.78, P = 0.008). There was a tendency for symptomatic fatigue to be inversely associated with average fiber SDH activity (r = -0.57, P = 0.068). The results of this study suggest that the inherent characteristics of skeletal muscle fibers per se and of skeletal muscle as a whole are altered in the direction of disuse in MS. They also suggest that changes in skeletal muscle in MS may significantly affect function.
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PMID:Strength, skeletal muscle composition, and enzyme activity in multiple sclerosis. 939 Sep 73

This study examined the influence of spinal cord injury (SCI) on affected skeletal muscle. The right vastus lateralis muscle was biopsied in 12 patients as soon as they were clinically stable (average 6 wk after SCI), and 11 and 24 wk after injury. Samples were also taken from nine able-bodied controls at two time points 18 wk apart. Surface electrical stimulation (ES) was applied to the left quadriceps femoris muscle to assess fatigue at these same time intervals. Biopsies were analyzed for fiber type percent and cross-sectional area (CSA), fiber type-specific succinic dehydrogenase (SDH) and alpha-glycerophosphate dehydrogenase (GPDH) activities, and myosin heavy chain percent. Controls showed no change in any variable over time. Patients showed 27-56% atrophy (P = 0.000) of type I, IIa, and IIax+IIx fibers from 6 to 24 wk after injury, resulting in fiber CSA approximately one-third that of controls. Their fiber type specific SDH and GPDH activities increased (P </= 0.001) from 32 to 90% over the 18 wk, thereby approaching or surpassing control values. The relative CSA of type I fibers and percentage of myosin heavy chain type I did not change. There was apparent conversion among type II fiber subtypes; type IIa decreased and type IIax+IIx increased (P </= 0.012). Force loss during ES did not change over time for either group but was greater (P = 0.000) for SCI patients than for controls overall (27 vs. 9%). The results indicate that vastus lateralis muscle shows marked fiber atrophy, no change in the proportion of type I fibers, and a relative independence of metabolic enzyme levels from activation during the first 24 wk after clinically complete SCI. Over this time, quadriceps femoris muscle showed moderately greater force loss during ES in patients than in controls. It is suggested that the predominant response of mixed human skeletal muscle within 6 mo of SCI is loss of contractile protein. Therapeutic interventions could take advantage of this to increase muscle mass.
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PMID:Influence of complete spinal cord injury on skeletal muscle within 6 mo of injury. 988 50

Percutaneous biopsies were taken from the right vastus lateralis (VL), tibialis anterior (TA), soleus (Sol), and lateral gastrocnemius (LG) muscles of eight recreationally active adult males. Approximately 60 fibers in each sample were analyzed for their type (I, IIa, or IIx), cross-sectional area (CSA), and succinic dehydrogenase (SDH), alpha glycerol phosphate dehydrogenase (GPDH) and calcium-activated actomyosin adenosine triphosphatase (qATPase) activities. This was done to test the hypothesis that metabolic enzyme activities are more reflective of the functional diversity among human locomotor muscles than fiber type composition. The results showed that enzymatic characteristics differed more or less than expected between muscles of the same or different fiber type. For example, the relative CSA occupied by fast fibers was only about 50% greater in the mixed (LG and VL) than in the slow (Sol and TA) muscles (57 vs. 38%). At the same time, average fiber SDH activity and fiber type specific SDH:qATPase*%CSA, both used as estimates of fatigue resistance, were greater in Sol and LG than in TA and VL. As a result, the two slow muscles and the two mixed muscles had different values, and a mixed muscle (LG) had higher values than a slow muscle (TA). The findings suggest that differences in enzymatic profile, more than fiber type composition, afford human locomotor muscles the capacity to perform their purportedly divergent functional tasks.
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PMID:Metabolic enzymes and phenotypic expression among human locomotor muscles. 1135 24


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