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)

Human neutrophils, activated by phorbol myristate acetate in the presence of intact red blood cells (RBCs), caused inhibition of the Ca2+ pump ATPase of the RBCs and fragmentation of the enzyme as well as other membrane proteins. Inhibition of the Ca2+ pump ATPase of intact RBCs was directly related to the neutrophil concentration and the time of incubation. Ca2+ pump ATPase activity was partially protected by the addition of exogenous glutathione-glutathione peroxidase, but not by superoxide dismutase. The addition of sodium azide, a potent inhibitor of endogenous RBC catalase, enhanced inhibition of the Ca2+ pump ATPase of intact RBCs. Examination by SDS-polyacrylamide gel electrophoresis of membrane proteins isolated from RBCs preincubated with activated neutrophils showed gross changes in banding patterns as compared to controls. Thus, a significant amount of methemoglobin appeared to be associated with the membrane proteins, and, in general, protein bands appeared to be more diffuse and less defined than proteins in control lanes. In addition, there was an increase in the low molecular weight protein bands. Using a monoclonal antibody to the Ca2+ pump ATPase, it was shown that the 140 kDa band representing the Ca2+ pump ATPase decreased, with concomitant appearance of two low molecular weight bands running at 8.2 and 6.8 kDa in the membrane proteins from RBCs preincubated with activated neutrophils. The data are interpreted to suggest that inhibition of the Ca2+ pump ATPase in intact RBCs under these conditions occurred as a result of: neutrophil-derived superoxide, dismutation of superoxide, to H2O2, diffusion of H2O2 into RBCs, a Fenton type reaction between oxyhemoglobin, and H2O2 producing hydroxyl radical and/or a ferryl radical capable of promoting protein fragmentation of RBC membrane proteins, including the plasma membrane Ca2+ pump ATPase.
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PMID:Inhibition by activated neutrophils of the Ca2+ pump ATPase of intact red blood cells. 775 Jul 90

The purpose of this research is to observe the near-UV radiation induced damage to cultured rabbit and squirrel lens epithelial cells as related to destruction and alterations of specific biochemical targets in the cells and to determine protective effects on the cells and targets that are provided by alpha-tocopherol. Confluent monolayers of cultured rabbit and squirrel lens epithelial cells were exposed to black light (BL) lamps, which emit predominantly UV-A radiation. These cells received a mixture 3 J/cm2 of UV-A and 4 mJ/cm2 of UV-B per h. This mixture is termed near UVA (i.e.: predominantly UV-A). Cells were exposed in Tyrode's or in MEM without or with alpha-tocopherol added at 2.5-10 micrograms/ml. Analyses of cell viability and survival, the physical state of cytoskeletal actin, and the activities of Na-K-ATPase and catalase were made. Exposure to near UVA damaged these cells as measured by vital staining and colony forming ability. Pretreatment with alpha-tocopherol decreased the magnitude of near UVA cytotoxicity. Near UVA exposure in MEM always produced more damage to the cells and biochemical targets than in Tyrode's. Cytoskeletal actin was degraded and the activities of Na-K-ATPase and catalase were markedly inhibited by UV-exposure. All of these targets were at least partially protected by alpha-tocopherol in the medium. Without alpha-tocopherol added to the media, the viability and survival of the cells did not recover even after 25 h of incubation. Cell viability was better protected from near UVA by alpha-tocopherol than was the ability to grow into colonies. This indicates that alpha-tocopherol protects actin, catalase, and Na-K-ATPase from near UVA damage.
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PMID:Damage to cultured lens epithelial cells of squirrels and rabbits by UV-A (99.9%) plus UV-B (0.1%) radiation and alpha tocopherol protection. 777 56

The aim of this study was to observe membrane injury and to investigate the mechanism of antioxidant defence systems against acute ethanol toxicity. Erythrocyte superoxide dismutase and Na+, K(+)-ATPase activities were significantly decreased and catalase levels were significantly increased one hour after ethanol intoxication of male swiss albino rats. These data demonstrated that superoxide dismutase and catalase are susceptible to lipid peroxidation and that these enzymes protect tissues from free radicals. The possible mechanism involved in Na+, K(+)-ATPase and Ca(2+)-ATPase inhibition are discussed in relation to the development of ethanol toxicity and the role of lipid peroxidative processes.
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PMID:Ethanol induced oxidative stress and membrane injury in rat erythrocytes. 786 12

Using light microscopy enzyme cytochemistry to localize catalase activity in peroxisomes, a population of peroxisome-negative hepatocytes was detected in livers of rats during liver regeneration induced by two-thirds partial hepatectomy. However, examination by electron microscopy revealed that this population of hepatocytes contained peroxisomes with a delimiting membrane and a nucleoid, but no cytochemically demonstrable catalase activity within their matrix. Regenerating livers 6, 18, 24, 36, 48 and 72 hours, and 1 week after partial hepatectomy showed hepatocytes without catalase activity. However, their numbers varied, with the most numerous appearing at 24 hours after partial hepatectomy. Mitosis of catalase-negative hepatocytes were seen along with mitosis of hepatocytes containing the normal complement of catalase-positive peroxisomes. The catalase-negative hepatocytes did not show evidence of apoptosis or necrotic cell death. Lysosomal acid phosphatase activity and bile canalicular ATPase activity were present in hepatocytes with catalase-negative peroxisomes. Another population of hepatocytes with a small number of catalase-positive peroxisomes appeared and were more numerous at 36 hours after partial hepatectomy; ultrastructurally, these hepatocytes contained both catalase-negative peroxisomes, which appeared to undergo dissolution, and catalase-positive peroxisomes, which were smaller in size. After complete restoration of the liver, all hepatocytes displayed essentially uniform numbers of catalase-positive peroxisomes. These studies indicated that during liver regeneration there is a transient loss of catalase in peroxisomes of some hepatocytes. These cells proliferate and with time acquire new catalase-positive peroxisomes. The observations are discussed in relation to peroxisome biogenesis, hepatocellular carcinogenesis, and oxidative stress during liver regeneration.
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PMID:Catalase-negative peroxisomes: transient appearance in rat hepatocytes during liver regeneration after partial hepatectomy. 788 49

Normal human bronchial epithelial (NHBE) cells are the putative progenitor cells of all types of lung cancer. NHBE cells immortalized by SV40 T-antigen retain many characteristics of the primary cells and are a useful model for investigating the role of oncogenes, tumor suppressor genes, and certain chemical carcinogens in the molecular pathogenesis of lung cancer. In this study, SV40 T-antigen-positive cells (BEAS-2B) were characterized for their metabolic functions and were shown to continue to express epoxide hydrolase, glutathione S-transferase pi, glutathione peroxidase, and catalase. To increase their metabolic activity towards human procarcinogens, human cytochrome P450 1A2 (CYP1A2) was stably expressed by introducing CYP1A2 cDNA into BEAS-2B cells either by infection with a high-titer recombinant retrovirus (pXT-1A2) or by transfection with a CYP1A2 expression vector (pCMV1A2), which produced the cell lines B-1A2 and B-CMV1A2, respectively. Cell lines established with either expression system expressed enzymatically active CYP1A2 protein and were 50- to 400-fold more sensitive to the cytotoxic effect of the carcinogen aflatoxin B1 (AFB1) than the corresponding control cell lines. The cytotoxic effects of AFB1 were paralleled by increased metabolism of AFB1 and enhanced formation of the AFB1-N7 guanine adduct in B-CMV1A2 cells. Cytotoxicity and adduct formation correlated with a significantly higher protein expression of CYP1A2 by the cytomegalovirus promoter-driven plasmid. Since this human epithelial cell line is the precursor cell type of lung cancer, has normal phase II enzymes, and exhibits highly reproducible expression of phase I enzymes, this in vitro model should aid in the evaluation of putative human carcinogens and anticarcinogens.
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PMID:Activation of promutagens in a human bronchial epithelial cell line stably expressing human cytochrome P450 1A2. 791 94

The membrane fluidity of the cardiac sarcoplasmic reticulum in rabbit was monitored by measuring changes in steady-state fluorescence anisotropy (rs) using diphenylhexatriene as a probe. The Ca(2+)-ATPase activity of the sarcoplasmic reticulum was measured by assaying the amount of inorganic phosphate released from ATP. Hydrogen peroxide caused damage to the sarcoplasmic reticulum, as reflected by decreases in membrane fluidity and Ca(2+)-ATPase activity. The damage caused by hydrogen peroxide was completely prevented by 20 micrograms/ml catalase. Cicaprost (240 nM) provided an effective protection against injury to the sarcoplasmic reticulum caused by exposure to hydrogen peroxide. The rs value was significantly decreased from 0.154 +/- 0.014 to 0.122 +/- 0.005 (p < 0.01). Ca(2+)-ATPase activity was increased from 3.1 +/- 1.31 to 18.87 +/- 2.11 microM phosphate/mg protein/hour (p < 0.01). The protection given by cicaprost was dose dependent. We conclude that cicaprost protects against damage produced by hydrogen peroxide in cardiac sarcoplasmic reticulum in the rabbit. The mechanism of the effect of cicaprost remains to be elucidated.
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PMID:Prostacyclin analog (cicaprost) protects against damage by hydrogen peroxide to rabbit cardiac sarcoplasmic reticulum. 820 98

To determine the effects of oxidant injury on specialized functions of proximal tubular epithelial cells, we determined sodium-dependent uptake of glucose ([alpha-14C]methylglucoside) and phosphate (32Pi) in LLC-PK1 cells after exposure to 0-500 microM hydrogen peroxide. Oxidant stress resulted in significant (P < 0.01) inhibition of glucose and phosphate transport. Decreased transport of glucose and phosphate was associated with marked ATP depletion, decreased activity of the sodium pump as determined by 86Rb uptake, direct inhibition of Na(+)-K(+)-adenosinetriphosphatase (Na(+)-K(+)-ATPase) activity, and an increase in intracellular sodium content, whereas intracellular potassium content declined. Decreased glucose and phosphate transport, inhibition of 86Rb uptake and Na(+)-K(+)-ATPase activity, and altered intracellular ion content were prevented by catalase and partially prevented by the membrane-permeable iron chelator phenathroline, whereas the slowly membrane-permeable iron chelator deferoxamine had little or no effect. To determine whether oxidant injury could also inhibit transporter function at the membrane level, plasma membrane vesicles were isolated from LLC-PK1 cells exposed to 500 microM hydrogen peroxide. Such membrane vesicles exhibited decreased sodium-dependent glucose transport, whereas sodium-dependent phosphate transport was not altered. We conclude that oxidant injury results in ATP depletion and inactivation of Na(+)-K(+)-ATPase which leads to disruption of the normal ion gradients sufficient to interfere with glucose and phosphate transport. Glucose transport is also inhibited by disruption of transporter activity within the plasma membrane. These alterations are mediated in part by the intracellular generation of an iron-dependent radical.
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PMID:Oxidant-induced alterations in glucose and phosphate transport in LLC-PK1 cells: mechanisms of injury. 821 96

The effects of ischemia and reperfusion with and without oxygen radical scavengers and xanthine oxidase inhibitors on Ca(2+)-ATPase activity were examined in the rat liver of 5 min ischemia followed by 5 and 10 min reperfusion. Ischemia was produced by the ligation of right hepatic artery and right portal vein. Superoxide dismutase, catalase and allopurinol were administered by subcutaneous injection of 60,000U/kg, 90,000U/kg and 200mg/kg, respectively before ligation. Reaction products of Ca(2+)-ATPase were morphometrically analyzed by RUZEX IIIU. Histochemically, Ca(2+)-ATPase activities were demonstrated on plasma membrane of liver cells, bile canaliculi and Kupffer cells involving mitochondria in liver cells of control rats. Ca(2+)-ATPase activities were depressed in the central lobes of liver after 5 min ischemia followed by 5 and 10min reperfusion. However, the activities of Ca(2+)-ATPase were not depressed by addition of oxygen radical scavengers and xanthine oxidase inhibitor before ischemia. These results suggest that oxygen free radicals may influence Ca(2+)-ATPase activity and contribute to liver cell damage due to ischemia-reperfusion.
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PMID:[The role of Ca(2+)-ATPase and oxygen radical in reperfusion injury of rat liver]. 827 65

The polyene antibiotic amphotericin B has been implicated in vascular injury in human subjects and lung injury in an animal model. Our objective was to determine whether amphotericin B directly injures endothelial cells and to investigate several possible mechanisms of injury. Confluent cultures of bovine endothelial cells were incubated with different concentrations of amphotericin B for varying time periods. Injury was assessed by using a chromium 51 release assay, adherent cell counts, and morphologic changes in the endothelial cell monolayers by phase microscopy. Amphotericin B increased 51Cr release in a dose- and time-dependent fashion. Corresponding to changes in 51Cr release, amphotericin B decreased adherent cell counts and disrupted the monolayers. Incubation with vehicle alone (sodium desoxycholate, 8.2 micrograms/ml) did not alter any of these parameters. Incubation of cells with a dose of antibiotic (1 micrograms/ml), which did not produce overt cell injury, significantly increased membrane permeability to K+ ions and activated the sodium/potassium adenosine triphosphatase (Na/K ATPase). Inhibition of the ATPase at this same antibiotic concentration (1 micrograms/ml) produced endothelial cell injury equivalent to the magnitude of injury observed with high doses of the antibiotic (10 micrograms/ml). In the presence of 10% fetal calf serum, the injury at 24 hours was significantly attenuated. This protective effect could not be attributed to binding of the drug by albumin because varying concentrations of bovine serum albumin in minimal essential medium without other serum constitutents had no effect on the magnitude of injury. Incubation of cells with several exogenous oxygen radical scavengers (dimethylthiourea, catalase, and mannitol) or a decrease in ambient oxygen tension during antibiotic exposure did not alter the magnitude of injury. The results demonstrate that amphotericin B directly injures endothelial cells in a dose- and time-dependent manner and demonstrate the importance of the Na/K ATPase for the maintenance of normal endothelial cell function and viability in response to this form of injury.
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PMID:Characteristics of amphotericin B-induced endothelial cell injury. 843 33

Preincubation of red blood cell membranes in the presence of ferrous sulfate and EDTA resulted in both a concentration- and time-dependent inhibition of the Na+/K+ pump ATPase, basal Ca2+ pump ATPase, and the calmodulin- (CaM) activated Ca2+ pump ATPase. The IC50 for all three ATPases was approximately 2.5 x 10(-5) M iron. The addition to membranes of ferrous iron and EDTA in an approximately 1:1 ratio resulted in conversion to the ferric iron form in several minutes. However, inhibition of the ion pump ATPases and cross-linking of membrane proteins occurred over the course of several hours. The time course of formation of thiobarbituric acid-reactive substances (TBARS) closely paralleled inhibition of the ion pump ATPases. Inhibition of the ion pump ATPases was prevented by the addition of deferoxamine or superoxide dismutase but not by mannitol, or catalase. Both butylated hydroxytoluene and tirilazad mesylate (U74006F) prevented the formation of TBARS, limited the inhibition of the ion pump ATPases, and reduced cross-linking of membrane proteins. These data may be interpreted to suggest that inhibition of ion pump ATPases in plasma membranes may occur as a result of iron-promoted formation of superoxide and subsequent lipid peroxidation, which can be prevented by free-radical scavengers including butylated hydroxytoluene and U74006F.
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PMID:Ion transport ATPases as targets for free radical damage. Protection by an aminosteroid of the Ca2+ pump ATPase and Na+/K+ pump ATPase of human red blood cell membranes. 839 84


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