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)

Slow (m.soleus) and fast (m.tibialis anterior) muscles of the rabbit were subjected to indirect long-term intermittent stimulation (3 weeks, 8 hrs daily) with a frequency pattern of 10 imp/sec. Whereas no changes were observed in case of the slow muscle, stimulation induced profound changes in the fast tibialis anterior muscle. These consisted in a rearrangement of the enzyme activity pattern of energy-supplying metabolism, e.g. decrease in glycogenolytic and glycolytic enzyme activities and severalfold increase in key enzymes of aerobic endoxidation of substrates in beta-oxidation and the citric acid cycle. Concomitant with the increase in aerobic oxidative capacity, there was an increased resistance to fatigue. Histochemical studies revealed a strong increase in mitochondria of all fibres. The bimodal distribution of fibre cross-sectional area in the normal tibialis anterior muscle was changed by stimulation into a more homogeneous population of fibres with a smaller cross-sectional area. Despite a 50% increase in time to peak of isometric twitch contraction no changes were observed in the fibre population with regard to myofibrillar ATPase reaction in quantitative evaluation of whole cross-sections of the muscles. The percentage of fibres histochemically classified as slow amounted to 2.8% and 3.1% in control and stimulated tibialis anterior muscle. Nevertheless the data suggest a transformation of the fibre population under the influence of long-term intermittent stimulation.
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PMID:Influence of intermittent long-term stimulation on contractile, histochemical and metabolic properties of fibre populations in fast and slow rabbit muscles. 12 33

Based on oxidative enzyme activity levels, fibres exhibiting moderate and high levels may be identified in the soleus of the rat. Fibres showing moderate activity are classified as Type I fibres, while those showing high activity may belong to Type I or Type II. According to the level of ATPase activity in fixed sections, we can distinguish three types of fibres in the soleus of the rat (IA, IB and II) and, by application of acid pre-incubation, also sub-classes of Type II (IIA and IIC). Type IB fibres possess high oxidative and glycolytic enzyme activities, moderate ATPase activity after fixation, and behave in the same way as Type I fibres after alkaline and acid pre-incubation. For the histochemical classificationof fibre types, we should consider not only reactions to ATPase, and after acid pre-incubation, but also reactions to the enzymes of oxidative and glycolytic metabolism.
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PMID:Histochemical type I fibres in the soleus of the rat. 15 94

A smooth muscle plasma membrane vesicular fraction (PMV) purified for the (Ca2+/Mg2+)-ATPase has endogenous glycolytic enzyme activity. In the presence of glycolytic substrate (fructose 1,6-diphosphate) and cofactors, PMV produced ATP and lactate and supported calcium uptake. The endogenous glycolytic cascade supports calcium uptake independent of bath [ATP]. A 10-fold dilution of PMV, with the resultant 10-fold dilution of glycolytically produced bath [ATP] did not change glycolytically fueled calcium uptake (nanomoles per milligram protein). Furthermore, the calcium uptake fueled by the endogenous glycolytic cascade persisted in the presence of a hexokinase-based ATP trap which eliminated calcium uptake fueled by exogenously added ATP. Thus, it appears that the endogenous glycolytic cascade fuels calcium uptake in PMV via a membrane-associated pool of ATP and not via an exchange of ATP with the bulk solution. To determine whether ATP produced endogenously was utilized preferentially by the calcium pump, the ATP production rates of the endogenous creatine kinase and pyruvate kinase were matched to that of glycolysis and the calcium uptake fueled by the endogenous sources was compared with that fueled by exogenous ATP added at the same rate. The rate of calcium uptake fueled by endogenous sources of ATP was approximately twice that supported by exogenously added ATP, indicating that the calcium pump preferentially utilizes ATP produced by membrane-bound enzymes.
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PMID:Comparison of endogenous and exogenous sources of ATP in fueling Ca2+ uptake in smooth muscle plasma membrane vesicles. 131 Oct 20

The role of neuromuscular activity in maintaining the normal enzyme heterogeneity found in a predominantly fast mixed muscle was studied. Enzymatic profiles of single fibers in the adult cat medial gastrocnemius (MG) were examined after almost complete elimination of neuromuscular activity for 6 mo. Inactivity was achieved by spinal cord isolation (SI), i.e., spinal transection at T12-T13 and L7-S1 combined with bilateral dorsal rhizotomy between the two transection sites. Cross-sectional area and succinate dehydrogenase (SDH) and alpha-glycerophosphate dehydrogenase (GPD) activities were determined in a population of fibers identified in frozen serial cross sections. Each fiber was categorized as light or dark on the basis of its staining characteristics for qualitative myosin adenosinetriphosphatase (ATPase), alkaline preincubation, and its reaction to fast and slow myosin heavy chain (MHC) antibodies. SI resulted in a conversion of nearly all light (approximately 36% in the control) to dark ATPase fibers. Virtually all MG fibers in the SI cats reacted with the fast MHC antibody, whereas very few fibers reacted with slow MHC antibody. On the basis of fiber cross-sectional area, it was estimated that the MG atrophied by approximately 10% after SI. Compared with the mean of the dark and light ATPase fibers in control (weighted by the percent fiber type distribution), mean SDH activity was significantly lower (approximately 70%) and mean GPD activity was significantly higher (approximately 120%) in the SI cats. These data indicate that prolonged electrical silence of a mixed fast hindlimb extensor results in virtually all fibers expressing fast MHC as well as oxidative and glycolytic enzyme profiles normally observed in fast glycolytic fibers.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Enzymatic responses of cat medial gastrocnemius fibers to chronic inactivity. 182 90

The metabolic plasticity of single fibers in adult cat medial gastrocnemius (MG) 6 mo after complete spinal cord transection (Sp) at T12-T13 was studied. Some Sp cats were trained to weight support (Sp-WS) 30 min/day beginning 1 mo posttransection. Cross-sectional area, succinate dehydrogenase (SDH), alpha-glycerophosphate dehydrogenase (GPD), and myofibrillar adenosinetriphosphatase (ATPase) activities were determined in fibers identified in frozen serial sections. Fibers were categorized as light or dark based on myosin ATPase staining, alkaline preincubation. The percentage of dark ATPase fibers was higher in Sp and Sp-WS (approximately 85%) than in control (approximately 60%). All dark ATPase fibers reacted positively to a fast myosin heavy chain monoclonal antibody. In both spinal groups, a higher percentage of dark ATPase fibers reacted to both fast and slow myosin heavy chain antibodies than in controls. Neither Sp nor Sp-WS cats showed fiber atrophy. Compared with control, SDH activity was decreased in both fiber types of Sp cats. Daily weight-support training ameliorated this adaptation. There were no differences among the three groups in mean GPD and ATPase activities for either fiber type. There was a slight tendency, however, for spinal cats to have higher GPD and ATPase activities (independent of type) than control, probably reflecting the larger proportion of dark ATPase fibers in these cats. These observations indicate that 6 mo after spinalization in adult cats, some of the fibers of a fast muscle became "faster" and developed oxidative and glycolytic enzyme profiles that normally are exhibited in fast fatigable motor units.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Enzymatic plasticity of medial gastrocnemius fibers in the adult chronic spinal cat. 214 12

This study was designed to determine the effects of reduced neuromuscular activity on the expression of proteins associated with contractile and metabolic functions and the size of single muscle fibers in the cat soleus. Adult cats were spinalized (Sp) at T12-T13 and maintained in a healthy condition for 6 months. Some of the cats were trained to weight-support (Sp-WS) for 30 minutes per day beginning one month posttransection. Cross-sectional area (CSA), succinate dehydrogenase (SDH), alpha-glycerophosphate dehydrogenase (GPD), and myofibrillar adenosine triphosphatase (ATPase) activities were determined in a population of single fibers identified in frozen serial cross-sections. Each fiber was categorized as either light or dark based on its staining density for qualitative myosin ATPase, alkaline preincubation (pH 8.75). The Sp (45%) and Sp-WS (31%) groups had significantly higher percentages of dark ATPase fibers than control (less than 1%). All dark ATPase fibers were shown to react positively for a fast myosin heavy chain monoclonal antibody, while some of these fibers showed a reaction to both fast and slow myosin heavy chain antibodies. Overall mean fiber CSA were significantly smaller (approximately 25%) than control in both Sp groups. In the Sp-WS, but not the Sp cats, the dark fibers were larger than the light fibers (P less than 0.05), suggesting a preferential effect of postural training on the ATPase converted fibers. There were no significant differences among the three groups in any of the mean enzyme activities for either ATPase type fiber. However, there was a general tendency for the Sp cats to have elevated GPD and ATP activities per muscle; this appeared to be directly related to the percentage of fibers staining darkly for myosin ATPase. These data indicate that 6 months after spinalization some of the fibers of the slow muscle developed fast myosin staining patterns and oxidative and glycolytic enzyme profiles that are normally exhibited in fast fatigue-resistant motor units. Periods of daily weight-support appear to ameliorate some of these adaptations to spinalization. Further, the observation that SDH activities are maintained at control values in spinalized adult cats as well as in spinalized kittens (unpublished observations) suggest that, at least in the soleus, skeletal muscle fibers can maintain their oxidative potential even though there is a marked reduction in neuromuscular activity for 6 months.
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PMID:Expression of a fast fiber enzyme profile in the cat soleus after spinalization. 214 97

Fluoride inhibition of carbohydrate metabolism by the acidogenic plaque microflora is well-established, although it has not always been appreciated that oral bacteria vary considerably in their susceptibility to fluoride. Early studies demonstrated that the F-induced reduction in acid production was due, in part, to the inhibition of the glycolytic enzyme, enolase, which converts 2-P-glycerate to P-enolpyruvate. The decreased output of PEP in the presence of F, in turn, results in the inhibition of sugar transport via the PEP phosphotransferase system (PTS). Bacterial accumulation of fluoride involves the transport of HF, a process requiring a transmembrane pH difference or pH gradient, which is generated only by metabolically active cells. The uptake of HF into the more alkaline cytoplasm results in the dissociation of HF to H+ and F- and, if allowed to continue, the accumulation of protons acidifies the cytoplasm, causing a reduction in both the proton gradient and enzyme activity. Current information indicates that in addition to enolase, F- also inhibits the membrane-bound, proton-pumping H+/ATPase, which is involved in the generation of proton gradients through the efflux of protons from the cell at the expense of ATP. Thus, fluoride has the dual action of dissipating proton gradients and preventing their generation through its action on H+/ATPase. The collapse of transmembrane proton gradient, in turn, reduces the ability of cells to transport solutes via mechanisms involving proton motive force. In spite of these known effects on the bacterial cell, there is no general agreement that the anti-microbial effects of F contribute to the anti-caries effect of fluoride.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Biochemical effects of fluoride on oral bacteria. 217 27

Chronic, rapid ventricular pacing produces congestive heart failure in dogs. The objectives of this study were to determine whether or not (i) in vitro myocardial biochemical alterations reported for heart failure by volume or pressure overload also occurred with heart failure due to rate overload, and (ii) these biochemical alterations were related to relevant in vivo cardiac physiologic alterations. We compared 27 dogs that were paced to advanced heart failure with 21 sham-operated dogs. Dogs with heart failure had 55% lower left ventricular ejection fraction (22.5 +/- 7.6 vs. 50.5 +/- 5.1%) and cardiac index (81 +/- 22 vs. 178 +/- 48 mL.min-1.kg-1), 287% higher pulmonary capillary wedge pressure (27.5 +/- 6.8 vs. 7.1 +/- 3.4 mmHg; 1 mmHg = 133.3 Pa), and 64% greater left ventricular diastolic area (18.4 +/- 3.7 vs. 11.2 +/- 1.3 cm2) (all p less than 0.05). Dogs with heart failure also had (i) 69% lower norepinephrine (232 +/- 139 vs. 747 +/- 220 ng/g protein), (ii) 25-50% lower activities of myofibrillar Ca ATPase (0.188 +/- 0.026 vs. 0.253 +/- 0.051 U/mg myofibrils), sarcoplasmic reticulum Ca-transport ATPase (0.155 +/- 0.074 vs. 0.288 +/- 0.043 U/mg membrane), and the glycolytic enzyme phosphofructokinase (33.4 +/- 10.0 and 47.7 +/- 15.8 U/g), (iii) 32% higher activity of the beta-oxidation enzyme hydroxyacyl-CoA dehydrogenase (11.43 +/- 1.48 vs. 8.67 +/- 1.70 U/g), and (iv) 60% higher activity of Krebs cycle oxoglutarate dehydrogenase (2.89 +/- 0.77 vs. 1.81 +/- 0.95 U/g) (all p less than 0.05). No differences between groups were observed for isozyme patterns and ATPase activity of myosin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Rapid ventricular pacing of dogs to heart failure: biochemical and physiological studies. 232 42

The storage lesion which limits the shelf life of human blood in blood banking is associated with a metabolic loss of 2,3-diphosphoglycerate and ATP. This metabolic loss is driven by intracellular ATPase which are usually considered to include the ion pumps and the reactions which maintain the discoid shape of the human erythrocyte. Under the acidic conditions of blood storage, the energy-yielding reactions of the glycolytic pathway are restricted at the hexokinase and phosphofructokinase steps. We show here that under such circumstances the enzyme of the diphosphoglycerate shunt, diphosphoglycerate mutase/phosphatase and the glycolytic enzyme phosphoglycerate kinase can form a futile cycle with ATPase activity. This ATPase activity responds to 2-phosphoglycolate which is known to activate both diphosphoglycerate mutase and diphosphoglycerate phosphatase reactions. When the enzymes of the futile cycle are combined with the enzymes of the lower glycolytic pathway in a reconstitution experiment designed to represent conditions within the stored erythrocyte, the futile cycle does provide an ATPase activity which results in the metabolic loss of 2,3-diphosphoglycerate. An isotope incorporation experiment demonstrates that the futile cycle is active in glucose-depleted erythrocytes.
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PMID:A futile cycle in erythrocyte glycolysis. 406 53

The reconstituted glycolytic system described previously (Scopes, 1973) was used to simulate post-mortem glycolytic metabolism in muscle. The effects of the following factors have been investigated: ATPase (adenosine triphosphatase) amount, AMP deaminase amount, percentage of the phosphorylase in the a form and the effect of diluting the glycolytic enzyme complex as a whole. It was confirmed that the rate of metabolism was solely dependent on the amount of ATPase present and that various concentrations of the glycolytic enzymes had no effect over a wide range encompassing the variation found in anatomically different muscles. The extent of metabolism, represented by the value of the ;ultimate' pH, depended markedly on the amount of phosphorylase in the a form; as little as 1% of the a form resulted in a considerably lower pH than in its absence. To a lesser extent the amount of AMP deaminase also affected the ultimate pH, but this was probably only significant for comparisons of genetically distinct muscles with widely differing amounts of AMP deaminase. The reconstituted system behaved almost identically with regard to post-mortem glycolytic metabolism compared with intact muscle tissue. It is concluded that the controlling effectors found with the reconstituted system apply to intact muscle also.
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PMID:Studies with a reconstituted muscle glycolytic system. The rate and extent of glycolysis in simulated post-mortem conditions. 428 Mar 4


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