Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.3.1 (Mg2+-ATPase)
 1,484 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Plasma membranes were isolated from rat liver mainly under isotonic conditions. As marker enzymes for the plasma membrane, 5'-nucleotidase and (Na+ + K+)-ATPase were used. The yield of plasma membrane was 0.6-0.9 mg protein per g wet weight of liver. The recovery of 5'-nucleotidase and (Na+ +K+)-ATPase activity was 18 and 48% of the total activity of the whole-liver homogenate, respectively. Judged from the activity of glucose-6-phosphatase and succinate dehydrogenase in the plasma membrane, and from the electron microscopic observation of it, the contamination by microsomes and mitochondria was very low. A further homogenization of the plasma membrane yielded two fractions, the light and heavy fractions, in a discontinuous sucrose gradient centrifugation. The light fraction showed higher specific activities of 5'-nucleotidase, alkaline phosphatase, (Na+ +K+)-ATPase and Mg2+-ATPase, whereas the heavy one showed a higher specific activity of adenylate cyclase. Ligation of the bile duct for 48 h decreased the specific activities of (Na2+ +K+)-ATPase and Mg2+-ATPase in the light fraction, whereas it had no significant influence on the activities of these enzymes in the heavy fraction. The specific activity of alkaline phosphate was elevated in both fractions by the obstruction of the bile flow. Electron microscopy on sections of the plasma membrane subfractions showed that the light fraction consisted of vesicles of various sizes and that the heavy fractions contained membrane sheets and paired membrane strips connected by junctional complexes, as well as vesicles. The origin of these two fractions is discussed and it is suggested that the light fraction was derived from the bile front of the liver cell surface and the heavy one contained the blood front and the lateral surface of it.
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PMID:Subfractionation of rat liver plasma membrane. Uneven distribution of plasma membrane-bound enzymes on the liver cell surface. 17 48

The article deals with oxidation of different substrates, intensity of glycolytic and glycogenolytic processes in mitochondria and homogenates of dog liver with its 2-hour exclusion from circulation under conditions of endotracheal ether-oxygen narcosis. It was established that already 30-60-minute ischemia causes a decrease in intensity of succinate, alpha-ketoglutarate oxidation and acceptor respiration, inhibiton in the activity of the citrate cycle enzymes; succinate dehydrogenase, alpha-ketoglutarate dehydrogenase, isocytrate dehydrogenase. The activity of NAD-dependent malate dehydrogenasedehydrogenase and Mg2+-ATPase as well as intensity of NADN oxidation in mitochondria increase. After 2-hour ischemia the activity of Mg2+-ATPase, cytochrome oxidase and peroxidase lowers. A sharply developed glycogenolysis is accompanied by inhibition of phosphorylase activity and a two-fold stimulation of the glycolytic reactions. Peculiarities in regulation of enzymatic reactions under conditions of ischemia and their role in origin of metabolism disturbances in the liver are under discussion.
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PMID:[Carbohydrate metabolism in the liver in acute ischemia]. 17 60

1. Effects of paracetamol treatment in vivo at subtoxic (375 mg kg-1 body weight) and toxic (750 mg kg-1 body weight) doses on energy metabolism in rat liver mitochondria were examined. 2. Paracetamol treatment resulted in a significant loss in body weights without affecting the liver protein contents. Toxic doses, however, resulted in 21% decrease in the yield of mitochondrial proteins. 3. Subtoxic doses of paracetamol did not, in general, affect the respiratory parameters in the liver mitochondria except in the case of succinate where both the state 3 respiration and the ADP-phosphorylation rates increased by 28%. 4. Toxic doses of paracetamol caused 25 to 47% decrease in the state 3 respiration rates depending on the substrate used. ADP/O ratios also decreased significantly with pyruvate + malate and succinate as the substrates. Consequently, ADP-phosphorylation was impaired significantly from 20 to 63%. 5. Subtoxic doses of paracetamol resulted in increased contents of cytochrome c + c1 while the toxic doses caused lowering of the cytochromes aa3 and b contents. 6. Glutamate and succinate dehydrogenase activities decreased in both the experimental groups while Mg2+-ATPase activity was impaired only after toxic dose-treatment. 7. The results show that toxic doses of paracetamol result in impaired energy coupling in the liver mitochondria. Effects of subtoxic doses were also demonstrable in terms of impaired dehydrogenases activities.
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PMID:Impaired mitochondrial oxidative energy metabolism following paracetamol-induced hepatotoxicity in the rat. 252 34

1. We performed an enzymatic characterization of two different fractionation procedures of ventricles from rat hearts. The enzymatic assays covered succinic dehydrogenase as a marker for inner mitochondrial membranes, monoamine oxidase as a marker for outer mitochondrial membranes, NADPH-cytochrome c reductase and RNA as endoplasmatic reticular markers, acid phosphatase as a lysosomal marker, and lactic dehydrogenase as a marker for the "soluble" compartment; DNA was estimated for nuclear contamination. 2. The plasma membrane markers 5'-nucleotidase, Ca2+-ATPase, Mg2+-ATPase, Na+-K+-ATPase, and adenylate cyclase were determined. 3. The roughly prepared membrane fractions showed increased yields of the membrane markers; the number of beta receptors, determined with (-)-[3H] dihydroalprenolol and DL-propranolol, amounted to 68 +/- 6 fmol/mg protein (KD = 3390 +/- 450 pmol, Hill coefficient = 1.5). 4. The membrane fraction prepared with a linear sucrose gradient showed an increased inner mitochondrial membrane marker; presumably the outer mitochondrial membrane was stripped off. The beta-receptor number was 39 +/- 3 fmol/mg protein (KD = 6250 +/- 300 pmol; Hill coefficient = 1.2).
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PMID:Beta-adrenergic receptors and enzymes in rat myocardial membranes: implications of fractionation procedures and beta-adrenoceptor antagonists. 284 52

Basal-lateral and brush border membranes from pig kidney cortex were prepared by differential centrifugation followed by free-flow electrophoresis. In each type of membrane, azide-insensitive, low-affinity Ca2+-ATPase and Mg2+-ATPase activities are demonstrated. A comparative study for both membranes further reveals the following analogies between these ATPases: (a) they show maximal activity between pH 8 and 8.5; (b) they exhibit Km values for Ca-ATP or Mg-ATP in the millimolar range and have a comparable low substrate specificity; (c) they are insensitive to 10 microM of vanadate, N,N'-dicyclohexylcarbodiimide, e diethylstilbestrol, quercetin, harmaline and amiloride. The partial inhibition by 1 mM of the various compounds is rather aspecific. In view of these similarities it is concluded that only one enzyme entity is responsible for the activity which is measured in both membrane types. The HCO3-stimulated Mg2+-ATPase activity in pig kidney cortex was also studied. This enzyme, however, is clearly of mitochondrial origin since the HCO3-stimulation coincides with the distribution profile of succinate dehydrogenase, a mitochondrial marker; and since it is inhibited by azide.
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PMID:An azide-insensitive low-affinity ATPase stimulated by Ca2+ or Mg2+ in basal-lateral and brush border membranes of kidney cortex. 316 26

The peroxidase activity in rat gastric mucosa is inhibited after administration of glucocorticoids. The synthetic steroid dexamethasone is more potent than the naturally occurring steroids, such as cortisone or corticosterone. Almost complete inhibition of the enzyme occurs after 24 h with a single dose of 100 micrograms dexamethasone/120 g body weight. Other mitochondrial enzyme activities, like monoamine oxidase, succinic dehydrogenase and Mg2+-ATPase, remain unaltered under the same experimental condition. Submaxillary peroxidase and thyroid peroxidase activity are not inhibited by dexamethasone. Gastric peroxidase activity is increased 200-250% on the 6th day after adrenalectomy. This effect is blocked by the administration of dexamethasone. In fact, the enzyme becomes more sensitive to dexamethasone after adrenalectomy, since it is inhibited by more than 90% at the dose of 25 micrograms/120 g body weight. The inhibition by dexamethasone in normal animals is reversible. The enzyme is also inhibited after the administration of a single dose of ACTH. The apparent Km of the enzyme for H2O2 is not altered after dexamethasone treatment or after adrenalectomy. The increase in enzyme activity following adrenalectomy is not blocked by actinomycin D or by alpha-amanitin, but is prevented by puromycin or cycloheximide. After administration of dexamethasone, the iodide concentration process in the gastric mucosa is not affected, but the organification of iodide is significantly diminished.
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PMID:Glucocorticoid effects on gastric peroxidase activity. 608 14

The activities of adenine nucleotide translocase (ANT), Na+-K+-ATPase (EC 3.6.1.3) and Mg2+-ATPase (EC 3.6.1.3) together with mitochondrial marker enzymes, succinic dehydrogenase (EC 1.3.99.1) and glutamate dehydrogenase (EC 1.4.1.2), were measured in liver, kidney, brain and testis from normal and thyroidectomised rats. Na+-K+-ATPase decreased by approximately 50% in liver and kidney; ANT decreased only in liver (-40%) while the activity of ANT per gram kidney increased by 38%. The activity of Mg2+-ATPase closely correlated with the pattern of change of ANT. The hormonal and substrate regulation of ANT is discussed in relation to its role in the regulation of intracellular phosphate potential and compartmentation in liver and kidney.
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PMID:Adenine nucleotide translocase, Na+-K+-and Mg2+-ATPases and differential tissue response to hypothyroidism. 612 72

Lantana camara caused, in guinea pigs, a decrease in hepatic mitochondrial protein content. The phospholipid to protein ratio did not change but there was a marked increase in the cholesterol to protein ratio and the cholesterol to phospholipid ratio. Enzyme activities of succinic dehydrogenase, glutamate dehydrogenase, cytochrome oxidase and Mg2+-ATPase increased, while the activity of NADH-ferricyanide reductase remained unaffected. Mitochondrial swelling, in the absence or presence of ascorbic acid, decreased in hepatic mitochondria from lantana-intoxicated guinea pigs.
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PMID:Biochemical effects of the plant Lantana camara on guinea pig liver mitochondria. 713 17

High-purity viable cells with low mitochondria (pavement cells) and mitochondria-rich content (chloride cells) were successfully isolated from the gill epithelium of Japanese eels, using three-step Percoll gradient low-speed centrifugation. Cytochemistry (silver staining for chloride, rhodamine-123, and Mitotracker for mitochondria and actin/spectrin immunofluorescence) and scanning electron microscope images were used to identify the cell types in the gill epithelium of the eel. Pavement cells were isolated at 97 and 98% purity for freshwater- and seawater-adapted eels, respectively, and chloride cells were obtained at 89 and 92% purity. The enzymatic activities of the isolated cells were determined. Na+-K+-ATPase, Mg2+-ATPase, and succinate dehydrogenase were found mainly in the chloride cell. Alkaline Ca2+-ATPase and low- and high-affinity Ca2+-ATPase were about twice as high in the chloride cell compared with the pavement cell. Transfer of eels to seawater resulted in enlargement of chloride cell sizes and significant increases in Na+-K+-ATPase, Mg2+-ATPase, and succinate dehydrogenase activities, while all Ca2+-ATPases declined by approximately 60-80%. This is the first report demonstrating the successful isolation of freshwater chloride cells and also an exclusive method of getting high-purity seawater chloride cells. The isolated cells are viable and suitable for further cytological and molecular studies to elucidate the mechanisms of ionic transport.
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PMID:Isolation of viable cell types from the gill epithelium of Japanese eel Anguilla japonica. 995 Sep 13

Adriamycin, which is widely used in the treatment of various neoplastic conditions, exerts toxic effects in several organs. Adriamycin nephrotoxicity has been recently documented in a variety of animal species. The present study was designed to investigate the effect of lipoic acid on the nephrotoxic potential of adriamycin. The study was carried out with adult male albino rats of Wistar strain. Test animals were divided into four groups of six rats each as follows: Group I (control) received only normal saline throughout the course of the experiment. Group II (ADR) received intravenous injections of adriamycin through the tail vein (1 mg kg(-1) body wt day(-1)) once a week for a period of 12 weeks. Group III (LA) received lipoic acid (35 mg kg(-1) body wt day(-1)) intraperitoneally once a week for a period of 12 weeks. Group IV (ADR + LA) received a single injection of lipoic acid intraperitoneally 24 h prior to the administration of adriamycin through the tail vein once a week for a period of 12 weeks. Intravenous injections of adriamycin resulted in decreased activities of the glycolytic enzymes; hexokinase, phosphoglucoisomerase, aldolase and lactate dehydrogenase in the rat renal tissue. The gluconeogenic enzymes, glucose-6-phosphatase and fructose-1,6-diphosphatase, showed a decline in their activities on adriamycin administration. The transmembrane enzymes namely the Na+,K+-ATPase, Ca2+-ATPase, Mg2+-ATPase and the brush-border enzyme alkaline phosphatase also showed a decrease in their activities. This decrease in the activities of ATPases and alkaline phosphatase suggests basolateral and brush-border membrane damage. Decreased activities of the TCA cycle enzymes isocitrate dehydrogenase, succinate dehydrogenase and malate dehydrogenase, suggest a loss in mitochondrial function and integrity. Nephrotoxicity was evident from the increased excretions of N-acetyl-beta-D-glucosaminidase and gamma-glutamyl transferase in the urine of adriamycin administered rats. These biochemical disturbances were effectively counteracted on pre-treatment with lipoic acid, which brought about an increase in the activities of glycolytic enzymes, ATPases and the TCA cycle enzymes. On the other hand, the gluconeogenic enzymes showed a further decrease in their activities on lipoic acid pretreatment. LA pretreatment also restored the activities of the urinary enzymes to normal. These observations shed light on the nephroprotective action of lipoic acid rendered against experimental aminoglycoside toxicity.
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PMID:The influence of lipoic acid on adriamycin induced nephrotoxicity in rats. 1284 26


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