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)

Besides the Mg-ATPase, a Na,K-ATPase can be demonstrated in different fractions of smooth muscles of the A. carotis communis of the sheep. The highest activity of Mg-ATPase is observed in the heavy microsomal fraction. The Ca-ion may act as a complete substitute for the Mg-ion in the Mg-ATPase. The proportion of Na,K-ATPase is between 10 and 40%, depending on the preparative conditions used in the individual fractions. Fractionated salt treatment (LiBr, KC1, KBr) improved the assay of Na,K-ATPase but increased strength of the Tris-HC1-buffer considerably reduced its activity.
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PMID:Demonstration of a Mg-ATPase and a Na,K-ATPase from the arteria carotis communis of the sheep. 12 27

The experiments described are based on the hypothesis that prolongation of the depressant action of ethanol leads to compensatory changes in neuronal membrane structures involved in impulse conduction and transmission, and that these become manifest as increased tolerance and withdrawal hyperexcitability. Behavioral tolerance was tested by means of the tilted plane test in rats consuming 9-10 g ethanol/kg/day in a liquid diet fed ad lib., or given 5 g/kg every other day by stomach tube, or doses rising from 6 to 9 g/kg/day maintaining continuous intoxication. All treatments were continued for about three or four weeks before testing. Rats consuming ethanol at a self-regulated rate did not develop tolerance, evidently because sufficient alcohol levels were not built up. Prolonged intoxication induced a high degree of tolerance and withdrawal symptoms, whereas intoxication every other day induced an intermediate degree of tolerance. When no definite abstinence symptoms were associated with the behavioral tolerance, cation stimulated ATPase activity of the brain microsomal fraction was not changed. With increasing withdrawal excitability, there was a relative increase in Na+, K+-stimulated ATPase and an decrease in Mg2+-stimulated ATPase whereas total activity of the enzyme system was not altered. 14C-serine was used as a precursor in order to detect changes in the metabolism of membrane components. So far, only acute experiments have been carried out in vivo. Heavy intoxication (6 g ethanol/kg by stomach tube) inhibited labeling of brain microsomal lipids and proteolipids. In "hangover", proteolipid labeling had returned to the control level whereas lipid labeling was still depressed. Cerebral cortex slices from rats in a withdrawal state after prolonged intoxication, and from control rats, were incubated in vitro with 14C-serine. Unstimulated tissue showed no effect of the prior treatment. When electrical stimulation was applied, much more activity was recovered in microsomal lipids of slices from withdrawal animals than from controls.
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PMID:Ethanol-induced changes in cation-stimulated adenosine triphosphatase activity and lipid-proteolipid labeling of brain microsomes. 12 37

The effect of digoxin, at two different inotropic levels, was examined in normo- and hyperkalaemic dogs. For similar inotropic responses, normo- and hyperkalaemic dogs had similar levels of (Na+, K+)-ATPase inhibition and microsomal-bound digoxin.
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PMID:Dose response in vivo to digoxin in normo-and hyperkalaemia: associated biochemical changes. 12

Because it is generally agreed that the sarcoplasmic reticulum plays an important role in regulating the intracellular availability of Ca2+, the ability of rat microsomal fractions to accumulate Ca2+ was compared with that of microsomal fractions similarly prepared from guinea pig heart muscle. Despite a relatively high level of basic ATPase enzyme activity (19.2 +/- 2.6 muM Pi/mg of microsomal protein/10 min) rat microsomal fractions consistently accumulated significantly (p less than 0.001) less Ca2+ than did the guinea pig preparations, irrespective of whether the incubation medium contained oxalate. The microsomal yield obtained from the rat hearts was not significantly different (p less than 0.8) from that obtained for guinea pig heart muscle. Rat mitochondria similarly accumulated significantly less Ca2+ than did the guinea pig mitochondria. These observations substantiate a general hypothesis that rat heart cells may possess a relatively high intracellular concentration of free Ca.
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PMID:A possible explanation for the peculiar contractile behavior displayed by rat heart muscle. 12 52

Heterotopic cardiac transplantation was performed in rabbits. The calcium uptake and ATPase activities of microsomal fraction were studied in three groups (group I, normal controls; group II, early transplants; group III, late transplants) during severe rejection as characterized histologically and electrocardiographically. Group III showed a significant decrease in calcium uptake but no difference in ATPase activity compared with groups I or II. The results demonstrate that in the rejecting transplanted hearts there is an uncoupling of microsomal calcium uptake from this ATP splitting function.
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PMID:Calcium uptake and ATPase activity of microsomes from heterotopically transplanted rabbit heart. 12 53

1. The function of mitochondria, sarcotubular membranes (heavy microsomes), sarcolemma and myofibrils from the hind-leg skeletal muscle of about 60- and 150-day-old normal and myopathic (UM-X7.1) hamsters was examined. 2. The mitochondrial calcium uptake as well as mitochondrial phosphorylation and respiratory rates were lower in 60-day-old myopathic skeletal muscle, unlike 150-day-old myopathic animals, when pyruvate-malate and glutamate-malate were used as substrates. However, mitochondria from 150-day-old myopathic animals showed depressed glutamate-dependent respiratory and phosphorylation rates and succinate-supported initial rate of calcium uptake. 3. The microsomal calcium-uptake, but not calcium-binding, and Ca2+-stimulated adenosine triphosphatase (ATPase) activity of the 150-day-old myopathic skeletal muscle were lower than the control values. Although microsomal calcium-binding, calcium-uptake and ATPase activities of the 60-day-old myopathic muscle were not depressed significantly, the initial rate of calcium uptake was less than the control. 4. The sarcolemmal Ca2+-ATPase, but not Mg2+-ATPase or Na+ +K+-ATPase, activity was higher in 60-day-old myopathic muscle whereas the activities of all these enzymes from 150-day-old myopathic animals were higher than the control. On the other hand, the Na+ +K+-ATPase activities from 60- and 150-day-old myopathic animals were inhibited by ouabain to a lesser extent in comparison with the respective control values. 5. The myofibrillar Ca2+-ATPase and Mg2+-ATPase activities as well as inhibition of Mg2+-ATPase due to Na+ and K+ in myopathic muscle were no different from the control values. 6. The results reported here give further support to the view that different membrane systems of the dystrophic muscle are defective.
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PMID:Defective membrane systems in dystrophic skeletal muscle of the UM-X7.1 strain of genetically myopathic hamster. 12 86

The distribution of sodium-potassium adenosine triposphatase (Na-K-ATPase) activity in kidney sections has been studied by a method based on the hydrolysis of p-nitrophenyl phosphate in alkaline medium containing dimethyl sulfoxide. The products at each stage in the reaction sequence have been subjected to electron probe microanalysis. The initial product was identified as a mixture of KMgPO4 and Mg(PO4)2, and sequential analysis demonstrated the linearity of conversion of this product to a visible form. In human, rabbit and rat kidneys the distribution of activity was found to be essentially identical, with highest levels located in thick ascending limbs and distal convoluted tubules. The initial reaction was completely potassium dependent and was inhibited by ouabain in concentrations reflecting the relative sensitivity of microsomal Na-K-ATPase in each species. Measurement of initial product phosphorus by means of the electron probe is presented as a practical technique for direct quantitation of Na-K-ATPase activity in identified tubule segments.
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PMID:Renal sodium-potassium adenosine triphosphatase. Optical localization and x-ray microanalysis. 12 10

A study in the enzymatic properties of muscle membranes established that sarcolemma of the rabbit skeletal muscles contains the Ca2+-ATPase system which does not require Mg2+ for manifestation of ions activity. By some kinetic properties it differs from ATPase of myosin. The complex Ca-ATP2+ is a substrate of Ca2+-ATPase. Ions of a series of bivalent metals inhibit the latter as well as the passive transport of Ca2+, that may evidence for a definite relation of Ca2+-ATPase with Ca+2 transport in skeletal muscles. Acetyl cholinesterase and AMP-aminohydrolase are strongly bound with the sarcolemma. The sarcolemma structural organization is shown to play a certain role in manifestation of their activity. On the basis of the data obtained when studying the activity in the ATPase systems and dynamics of formation and decay of the intermediate phosphorylated product in the microsomal fraction of cow and rabbit myometrium certain peculiarities are established for the active mechanisms of Ca2+ transport in smooth muscles. A problem is under discussion on the possible active participation of sarcolemma in regulation of Ca2+ concentration in the smooth muscle cells. Two ATPase systems, Mg2+-dependent and Mg2+-dependent Ca2+ activated are found in nuclei; the role of lipids of the skeletal muscles in manifestation of their activity is studied. AMP-amino hydrolase properties are characterized for different areas of the sarcoplasmatic reticulum membranes. The model of E-avitaminous muscular distrophy was used to show disturbances in the structure of sarcolemma and membranes of the sarcoplasmatic reticulum which are accompanied by changes in their ATPase and Ca2+-transporting properties.
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PMID:[Enzymatic properties in muscle membranes]. 12 74

In immature rats the temperature dependence of Na+-K+ ATPase of a crude homogenate of brain shows a compex curve with two activity maxima. When EDTA was present in the homogenization medium the curve obtained was of simpler, curvilinear type showing an increased activity at temperatures above 20 degrees C. The Na+-K+ ATPase activity in similar preparation from adult brain were not complex but curvilinear whether EDTA was used or not; however, EDTA increased the activity at temperatures above 20 degrees C. When such chelating agents as EDTA or histidine were used in preparation of microsomes from immature rat brain, the temperature dependence curve of Na+-K+ ATPase in this membrane fraction was changed to a steeper and simpler curve with increased activity especially at temperatures above 20 degrees. These agents, however, did not eliminate totally the complex shape of curve found in microsomes prepared without the presence of any chelating agents. When microsomes were prepared by using NaI-technique the temperature dependence of this enzyme was linear between temperatures 15-14 degrees, the activity being 4-5-fold higher than in the ordinary microsomal preparation. A stimulation of the Mg2+ ATPase by Na+ ions (100mM) was found at temperatures below 30 degrees but an inhibition by the same concentration of Na+ at upper temperatures. This effect together with the lowered activity due to bivalent metal ions (e.g. Ca2+, Cu2+) in 'crude' preparations was thought to be reasons for the complex shape of temperature dependence curve of Na+-K+ ATPase activity.
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PMID:Temperature dependence of brain ATPases in immature and adult rats. 12 4

The microsomal fraction of the rabbit skeletal muscles contains structures which absorb Ca2+ and where ATPase-aminohydrolase activities are pronounced. Electrophoresis of this fraction in the saccharose density gradient results in separation of a considerable amount of soluble proteins including creatine kinase, as a high ATPase activity and absorbing Ca2+ to an inconsiderable extent. The activity of creatine kinase in the microsomal fraction of the rabbit and rat skeletal muscles is not so high to provide for ATP regeneration from creatine phosphate in the amount sufficient for any considerable transport of Ca2+. In the microsomal fraction of the myocardium, as distinct from the skeletal muscles creatine kinase is strongly bound with its structural components and is not separated by electrophoresis.
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PMID:[Distribution of the action of creatine kinase, AMP-aminohydrolase and ATPase,and absorption of Ca+n microsomal fractions of skeletal muscles]. 12 64


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