Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanical and energetic consequences of long-term volume-overload (VOL) hypertrophy have been investigated in rabbits and compared with the consequence in sham-operated controls (SOC). Hypertrophy was induced by creating an aortocaval shunt, and the mechanical, biochemical, and energetic properties of the compensated heart were examined approximately 12 wk later. At 27 degrees C and a stimulus frequency of 1 Hz there were no significant changes in peak stress development, 10-90% rise times, shortening velocity, work, and mechanical power output. There was, however, a prolongation of contractile duration. The inverse relationship between peak stress and cross-sectional area was unchanged in the VOL and SOC groups. Polarographic and myothermic experiments were made on papillary muscles. Hypertrophy produced a small increment in basal metabolism. In isometric studies there were no significant changes in either the activation heat magnitude or the slope of the heat-stress relationship. In isotonic contractions there was no change in work output or total enthalpy (heat + work), and as a result mechanical efficiency was unchanged. A force-length-area (FLA) analysis of the isotonic data showed no significant change in intercept or FLA contractile efficiency. Biochemical studies showed no significant difference in the myosin isoenzyme profile at the time of death. The Ca(2+)-stimulated adenosinetriphosphatase activity of the sarcoplasmic reticulum was unchanged as were the enzymatic activities of mitochondrial citrate synthase and alpha-ketoglutarate dehydrogenase. Interestingly essentially the same data were obtained from the hearts of four animals in failure and from the hearts of seven compensated animals.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mechanical, energetic, and biochemical changes in long-term volume overload of rabbit heart. 153 94

Na-K ATPase activity in the brain decreased significantly after diabetes was induced with streptozotocin in rats. Largest decreases were observed in the hippocampus (-30%) and the cerebral cortex (-26%). Smaller decreases were observed in the thalamus (-13%), hypothalamus (-11%) and brain stem (-10%). Na-K ATPase activity in the striatum and the cerebellum were not significantly decreased. The varied decreases suggest that the regional variation of the enzyme is enhanced in the diabetic state. The enzymes of glucose metabolic pathway, namely hexokinase, lactate dehydrogenase and citrate synthase in the brain regions largely remained unchanged although increases in lactate dehydrogenase were observed in some regions. Acetylcholinesterase activity, a marker for the cholinergic system, remains unaltered in the brain during diabetes. The results are discussed with respect to the possible metabolic factors which alter the Na-K ATPase in the brain and its comparison with the peripheral nerve.
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PMID:Diabetes induced by streptozotocin causes reduced Na-K ATPase in the brain. 166 46

Skeletal muscle grafts performed with neurovascular repair are used extensively in clinical situations. However, most controlled experimental studies on the efficacy of such grafts have been conducted on muscles with a relatively small mass and over a limited recovery period. Therefore, selected cellular and matrix component properties of the comparatively large dog gracilis muscle (75 g) were studied 9-12 mo after orthotopic neurovascular grafting. The grafted muscle wet weights were 71% of the contralateral control (sham-operated) muscles. In addition, the concentrations of noncollagenous protein (13%), DNA (28%), and RNA (34%) were significantly reduced in the grafts. However, the concentration of collagen was significantly higher (41%) in the grafts. In this regard, the type III collagen phenotype showed the greatest relative increase. There was no difference between the grafted and control proteoglycan concentration. The metabolic profiles of the grafted muscles were significantly different from control. The activities of myofibrillar adenosinetriphosphatase (34%) and alpha-glycerophosphate dehydrogenase (25%) were reduced, whereas citrate synthase remained unchanged. These data suggest that recovery of up to 1 yr was insufficient for the normalization of several connective tissue matrix components and biochemical properties of the grafts.
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PMID:Incomplete normalization of dog gracilis muscle grafts with neurovascular repair despite long-term recovery. 169 Jun 97

The purpose was to determine the biochemical and hemodynamic adaptations of the myocardium to chronic tachycardia. Cardiac pacemakers were implanted in Yorkshire pigs and set at a rate of 180 beats/min for a period of 35-42 days. Animals were then anesthetized with pentobarbital sodium. Myocardial blood flow and hemodynamics were determined at three different heart rates (i.e., 120, 180, and 220 beats/min). Tissue samples were then taken for microsphere and biochemical analyses. Chronically paced hearts maintained better cardiac function and had consistently higher left ventricular blood flow with a higher endocardial-to-epicardial ratio. The activities of citrate synthase and 3-hydroxyacyl-CoA dehydrogenase were 23 and 45% greater in the paced hearts, respectively. The sarcoplasmic reticulum adenosinetriphosphatase activity was 55% greater in the paced hearts, whereas the myosin adenosinetriphosphatase was the same as in the control hearts. Polyacrylamide gels of the ventricular myosin isoforms showed only the V3 type to be present in both the control and paced hearts. These findings show that the heart of a large mammal adapts to chronic tachycardia (i.e., 180 beats/min) by elevating the aerobic and calcium-sequestering capacities without altering its myosin type.
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PMID:Myocardial biochemical and hemodynamic adaptations to chronic tachycardia. 182 10

The purpose of this study was to determine whether cardiac biochemical adaptations are induced by chronic exercise training (ET) of miniature swine. Female Yucatan miniature swine were trained on a treadmill or were cage confined (C) for 16-22 wk. After training, the ET pigs had increased exercise tolerance, lower heart rates during exercise at submaximal intensities, moderate cardiac hypertrophy, increased coronary blood flow capacity, and increased oxidative capacity of skeletal muscle. Myosin from both the C and ET hearts was 100% of the V3 isozyme, and there were no differences between the myosin adenosine triphosphatase (ATPase) or myofibrillar ATPase activities of C and ET hearts. Also, the sarcoplasmic reticulum Ca(2+)-ATPase activity and Na(+)-Ca2+ exchange activity of sarcolemmal vesicles were the same in cardiac muscle of C and ET hearts. Finally, the glycolytic and oxidative capacity of ET cardiac muscle was not different from control, since phosphofructokinase, citrate synthase, and 3-hydroxyacyl-CoA dehydrogenase activities were the same in cardiac tissue from ET and C pigs. We conclude that endurance exercise training does not provide sufficient stress on the heart of a large mammal to induce changes in any of the three major cardiac biochemical systems of the porcine myocardium: the contractile system, the Ca2+ regulatory systems, or the metabolic system.
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PMID:Biochemical characterization of exercise-trained porcine myocardium. 183 67

This study compared the skeletal muscle metabolic adaptations in response to combined eccentric and concentric or concentric resistance training regimens. Twenty-six physically active males were assigned to either the combined eccentric and concentric group (n = 10), the concentric group (n = 10) or the control group (n = 6). The combined eccentric and concentric and the concentric groups performed four to five sets of maximal, voluntary bilateral quadriceps muscle actions at 1.05 rad s-1 using a speed-controlled dynamometer three times per week for 12 weeks. The concentric group performed 12 concentric actions per set, whereas the combined eccentric and concentric group performed six coupled eccentric and concentric actions per set. Bilateral percutaneous muscle biopsies were obtained from m. vastus lateralis at rest pre- and post-training. Tissue samples were analysed for contents of adenosine triphosphate, creatine phosphate and creatine and for enzyme activities of citrate synthase, lactate dehydrogenase, myokinase, phosphofructokinase, hexokinase and Mg2(+)-ATPase using fluorometric techniques. Histochemical staining procedures were employed to determine capillary supply. The overall increase (P less than 0.05) in muscle strength was greater (P less than 0.05) for the combined eccentric and concentric group than for the concentric group. Enzyme or substrate contents and capillary supply were unaltered after either type of training. It is suggested that substantial increases in muscle strength may occur in response to resistance training without enhancing or compromising metabolic function of skeletal muscle.
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PMID:Effects of eccentric and concentric resistance training on skeletal muscle substrates, enzyme activities and capillary supply. 208 17

The purpose of this study was to determine the extent to which functional demand regulates the biochemical character and enzyme capacities of the rat myocardium. Hearts from donor rats were heterotopically transplanted onto the abdominal aorta and inferior vena cava of isogenic recipients. The procedure results in a perfused but nonpumping heart that has a reduced heart rate (HR) and performs essentially no stroke work (SW). After 30 days, metabolic enzyme activities (phosphorylase, 6-phosphofructokinase, citrate synthase, and 3-hydroxyacyl-CoA dehydrogenase) were significantly lower (40-60%) in the nonworking heart. Specific sarcoplasmic reticulum Ca2(+)-adenosinetriphosphatase (ATPase) activity was unchanged, but activity per gram of heart was 41% lower. Myosin isozymes were 58% V1, 21% V2, and 21% V3 in the nonworking heart compared with 100% V1 in the working heart. Myosin and myofibrillar ATPase activities each decreased by 28%. These findings suggest that both HR and SW play major and specific roles in regulating myocardial biochemical capacities and determining the myosin phenotype.
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PMID:Role of cardiac work in regulating myocardial biochemical characteristics. 214 21

Skeletal muscle has an inherent biochemical phenotypic plasticity that provides the possibility for it to be remodeled into a "heart-like" muscle for use in cardiac-assist devices. The purpose of this study was to chronically stimulate skeletal muscle electrically to transform the biochemical capacities of the three major subcellular systems (i.e., metabolic, calcium regulating, and contractile) to resemble those of heart muscle. The latissimus dorsi muscle (LDM) of mongrel dogs weighing 22-27 kg was stimulated via the thoracodorsal nerve at 2 Hz for 6-8 wk. This stimulation protocol reduced the phosphorylase (glycogenolytic) and phosphofructokinase (glycolytic) activities by 70%. The aerobic (citrate synthase activity) and fatty acid oxidative (3-hydroxyacyl-CoA dehydrogenase activity) capacities were not significantly increased by chronic stimulation and remained at about one-fourth those in the canine heart. The calcium-dependent sarcoplasmic reticulum adenosinetriphosphatase (ATPase) activity in the microsomal fraction, which was sixfold greater in the nonstimulated LDM than in the heart, was reduced by electrical stimulation to a level similar to that of the dog heart. The contractile capacity was evaluated by determining the percentage of types I and II fibers, the myofibrillar ATPase activity, and the proportion of myosin isoforms. The transformed muscle was comprised of 93 +/- 2% type I fibers, a myofibrillar ATPase activity similar to that in heart with primarily a slow-twitch muscle myosin isoform. In conclusion, electrical stimulation of canine LDM at 2 Hz for 6-8 wk resulted in two of the three biochemical systems, which confer physiological expression and fatigue resistance to muscle being transformed to resemble those of the myocardium.
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PMID:Biochemical transformation of canine skeletal muscle for use in cardiac-assist devices. 214 Aug 28

The purpose of this study was to investigate metabolic changes in equine muscle from birth to 1 yr of age. Duplicate biopsies from the middle portion of the gluteus medius were obtained from a depth of 2 cm beneath the superficial fascia at 1 day, 7 days, 1 mo, 3 mo, 6 mo, and 1 yr of age in 11 quarter horses and at 1 day, 3 mo, 6 mo, and 1 yr of age in 5 Standardbreds. Muscle enzyme activities determined were citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, phosphorylase, and lactate dehydrogenase. Percent fast-twitch, fast-twitch high oxidative, and slow-twitch oxidative fiber types were determined using succinate dehydrogenase and myosin adenosinetriphosphatase (pH 9.4) histochemical stains. Histochemically determined muscle fiber-type percents did not change dramatically with increasing age. However, lactate dehydrogenase activity increased threefold in quarter horses and twofold in Standardbreds, and phosphorylase activity increased sixfold in quarter horses and sevenfold in Standardbreds from 1 day to 6 mo of age. Citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities decreased during the first 3 mo of age in quarter horses.
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PMID:Changes in the metabolic profile of equine muscle from birth through 1 yr of age. 234 82

Gill cell suspensions from freshwater (FW)- and seawater (SW)-adapted teleosts were obtained by density gradient centrifugation. The proportion of chloride cells (CCs) in the mixed cell suspensions was estimated using the fluorescent mitochondrial stain, DASPMEI, and ranged from less than 1% (FW-adapted tilapia) to approximately 13% (SW-adapted toadfish). The gill cells displayed relatively high viability based on Trypan Blue exclusion (greater than 75%), lactate dehydrogenase leakage (less than 6.5% h-1), oxygen consumption rates (5-15 mumol g-1 cell wet mass h-1) and ATP levels (1-3 mumol g-1 cell wet mass). There were no obvious differences between the viability of CCs and the other cell types present. An initial comparison of gill oxidative metabolism in SW-adapted tilapia (Oreochromis mossambicus) and toadfish (Opsanus beta) demonstrated that both species oxidized glucose and lactate at substantially greater rates than alanine or oleate. Metabolic rates were significantly higher in toadfish cell suspensions. Kinetic experiments revealed that toadfish gill cells displayed lower values of Km and higher values of Vm for both lactate and glucose, in comparison to tilapia. The elevated metabolism in toadfish gill cells was correlated with increased activities of the oxidative enzyme citrate synthase and Na+/K+-ATPase. The toadfish cell suspensions had a greater proportion of CCs and it is likely that the difference in CC numbers between the two species is the basis for the observed differences in enzyme activities and rates of oxidative metabolism. This idea is supported by the highly significant correlation between Na+/K+-ATPase activity (or CC numbers) and rates of lactate oxidation in gill cell suspensions from FW- and SW-adapted tilapia and toadfish, as well as SW-adapted tilapia chronically treated with cortisol to elevate CC numbers. Although it has been assumed widely that the high metabolic rate of gill tissue reflects, in part, the oxidative demands of the chloride cell, the results of this study provide the first experimental, albeit indirect, evidence for differential rates of metabolism in the various cell types that comprise the gill.
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PMID:Metabolism of isolated fish gill cells: contribution of epithelial chloride cells. 254 65


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