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)

Mesonephroi of sheep embryos ranging from 12 to 100 mm C.R. length were examined for the occurrence and localization of transport-ATPase. Native cryostat sections were incubated according to the technique of Guth and Albers for demonstrating the nitrophenylphosphatase activity of Mg2+-Na+-K+-adenosine triphosphatase. The basal cytoplasm of the collecting tubule of the narrow segment of the distal tubule exhibit strong activity, the wide segment of the distal tubule is moderately active. Glomeruli, proximal tubule, and Wolffian duct remain unstained. The basal labyrinths of the reactive nephron segments are believed to be the sites of a Na+-K+ exchange pump. In mature and regressing mesonephroi, the findings fully agree with biochemical data; in maturating mesonephroi, whose basal labyrinth is not yet fully established, the biochemical assay proves to be more sensitive. The specifity of the reaction was ascertained by diverse inhibitors and activating ions. The localization of Mg2+-ATPase is different to the above mentioned reaction pattern, as it shows moderate activity in the proximal tubule, too (mature mesonephros). Mesonephroi of very young embryos exhibit strongest Mg2+-ATPase activity in the proximal tubule; here the distal and collecting tubule stain only moderately.
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PMID:Histochemical localization of Mg2+-Na+-K+-adenosine triphosphatase in different stages of the sheep mesonephros. 12 45

Using quantitative cytochemistry, activities of Na, K-ATPase, succinate dehydrogenase (SDH) and alpha-keto-glutarate dehydrogenase (alpha-KDH) was investigated in cells of renal tubules at different levels of sodium reabsorption in the kidney. The activity of these enzymes in mammals and birds renal tubule cells was found to be higher than in the cells of corresponding renal tubules of cold-blooded vertebrates. This corresponds to the increased total amount of reabsorbed sodium in the kidney of warm-blooded animals. The summer frogs, as compared to the winter ones, exhibit higher activities of SDH and Na,K-ATPase in the proximal tubule cells where changes in sodium reabsorption are also noted. In the kidney of marine teleosts, a negative correlation between U/PNa and the activity of SDH and Na,K-ATPase in the cells of proximal and distal tubule was observed. Aldosterone was found to stimulate sodium reabsorption and to activate Na,K-ATPase.SDH and alpha-KDH mainly in the distal convoluted tubule. Furosemide was observed to inhibit sodium reabsorption and to reduce SDH and Na,K-ATPase activities in cells of the proximal tubule and Henle's loop. In the kidney of adrenalectomized rats, both sodium reabsorption and activities of Na,K-ATPase, SDH, alpha-KDH decreased in all the segments of the nephron. The data obtained suggest that changes in sodium reabsorption may be coupled with those in the activities of the investigated enzymes.
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PMID:[A cytophotometric analysis of the activity of oxidative enzymes and Na, K-ATPASE in vertebrate nephrons at different levels of sodium transport in the kidney]. 13 80

Brush border membranes (luminal) and basal-lateral plasma membranes (contraluminal) of rat kidney proximal tubules were isolated by freeflow electrophoresis and their role in transepithelial transport was investigated. Enzymatic analysis revealed that the brush border membranes contain a bicarbonate stimulated ATPase and that the basal-lateral plasma membranes contain a Na+-K+-ATPase and a calcium stimulated ATPase. These findings suggest that an active, ATPase-mediated step in transepithelial bicarbonate or proton transport is located in the luminal membrane, whereas an active, ATPase-mediated step in transepithelial sodium and calcium transport is located in the contraluminal membrane. Transport studies with membrane vesicles demonstrated that sodium-dependent stereospecific transport systems for sugars, amino acids and phosphate are located in the brush border membrane; the basal-lateral plasma membranes contain sodium-independent transport systems for sugars; amino acids, phosphate and p-aminohippurate. The sodium-dependent systems represent sodium-substrate contransport systems which in the course of transepithelial transport derive energy from the transmembranel electrochemical potential difference of sodium for the intracellular accumulation and active transepithelial transport of sugars, amino acids and phosphate. The brush border membrane contains in addition a Na+/H+ exchange system which might be involved in the proton secretion of the proximal tubule. In the presence of a sodium gradient the permeability of the luminal membrane vesicles for L-lactate is higher than the permeability of the contraluminal membrane vesicles. This indicates that L-lactate-which is metabolized by the tubular epithelium-enters the tubular cell mainly from the tubular lumen. The role of membranes in the uptake of proteins by the tubular cell was investigated by isolation and biochemical characterization of microvilli, pinocytic vesicles and lysosomes. Pinocytic vesicles were found to be rich in acid phospholipids and glycoproteins which show a more rapid turnover than the proteins of the microvilli. It is concluded that pinocytic vesicles are biochemically defined entities with unique functions which are synthetized during the pinocytic process.
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PMID:[Membrane function of the kidney]. 13 58

Single, defined nephron segments were dissected in vitro from fresh slices of neonatal and mature rabbit kidney. Na-K-ATPase was quantified for six different tubule segments with an ultramicromethod. The enzyme distribution pattern in the neonatal nephron was similar to that in the mature nephron. Activity in distal segments was 2-5 times higher than proximal tubule activity referred to tissue dry weight, and 2 times higher referred to tubule length. Neonatal enzyme activity was lower than mature in all segments. Some segments carried only 23% of mature activity. Enzyme activity in the proximal convoluted tubule was constant during maturation when referred to the basal and lateral membrane area measured in the same developmental stages. In vitro activities of these tubules were similar to the enzyme activity measured previously in freeze-dried slices. The Vmax during development of Na-K-ATPase was higher by a factor of 5 in the mature tubule, whereas the Km was identical in the neonatal and mature tubule. The ouabain-insensitive ATPase did not show a maturational activity change.
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PMID:Na-K-activated ATPase: activity maturation in rabbit nephron segments dissected in vitro. 14 90

A study has been made to determine whether renal plasma membranes contain an HCO3 stimulated, ouabain insensitive Mg ATPase. Purified mitochondrial, microsomal and brush border membrane fractions have been isolated from rabbit kidney. The microsomal anion-sensitive ATPase activity appears to be entirely of mitochondrial origin on the basis of the effects of inhibitors of mitochondrial Mg ATPase. The brush border membrane fraction is contaminated with mitochondrial fragments and contains an Mg ATPase activity with low anion-sensitivity. Further purification of this fraction causes parallel decreases in anion-sensitivity of the Mg ATPase activity and in cytochrome c oxidase activity. These results indicate that conclusions previously reached by other investigators for a role of anion-sensitive Mg ATPase in the bicarbonate reabsorption of the proximal tubule may no longer be tenable.
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PMID:Is there a plasma-membrane-located anion-sensitive ATPase? II. Further studies on rabbit kidney. 14 30

The relationship between lysozyme and sodium reabsorption by the kidney tubule was studied in the experimental Fanconi syndrome. Female, anesthetized Sprague-Dawley rats were injected intravenously with maleic acid (an inhibitor of sodium transport) neutralized with sodium hydroxide in doses of either 2 or 8 mmol/kg. Clearance studies were performed immediately afterward, and plasma and urine were analyzed for inulin, pH, sodium, glucose, and lysozyme. Two hours after the maleic acid injection, renal cortical tissue was removed and homogenized. Specific activity of Na-K-ATPase was assayed in the light microsomal fraction. The results showed that both concentrations of maleic acid caused significant increases in urinary volume, glucose excretion, and pH. There were significantly correlated decreases in TNafract and TLyfract. The slope of the regression line (TLyfract = 1.03 TNafract - 5.82; r = 0.92) approximated unity. Renal cortical Na-K-ATPase activity was significantly decreased by 25% in the animals receiving 2 mmol maleic acid and 43% in the animals receiving 8 mmol. The evidence suggests that lysozyme reabsorption in the proximal tubule might be mediated directly or indirectly by active tubular transport of sodium, a process that is related to the Na-K-ATPase transport system.
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PMID:Renal handling of lysozyme in experimental Fanconi syndrome. 14 77

HgC12-induced renal tubular lesions in the rat present histochemically with a transitory decrease of alkaline phosphatase, adenosinetriphosphatase (ATPase), and leucine-aminopeptidase activity. The toxic alterations of enzyme activity were more pronounced in the pars recta of the proximal tubule and in the loop of Henle, as compared with the tubulus contortus I. L-thyroxine treatment leads to an accelerated reversal of that enzymatic defect, followinga characteristic pattern, and to a differentiating increase of acid phosphatase and ATPase activity in certain parts of the normal renal tubule. The observations are discussed with reference to the specific mode of action of sublimate and l-thyroxine upon the tubular enzymes and to the well-known metabolic and functional influences of thyroid hormone on the kidney.
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PMID:Influence of L-thyroxine upon enzymatic activity in the renal tubular epithelium of the rat under normal conditions and in mercury-induced lesions. I. Histochemical studies of alkaline phosphatase, acid phosphatase, adenosine- tri-phosphatase and leucine-aminopeptidase. 19 Jul 63

Circulatory insufficiency in rats was induced by constriction of the thoracic portion of vena cava inferior. Two-three days after the operation renal function was studied and the activity of succinate dehydrogenase and Na+K+-ATPase in the cells of the renal tubules was determined cytochemically. On infusion of 0.9% NaCl solution into the stomach, the filtration in the "caval" rats did not change whereas the excretion of sodium and its concentration in the urine were much lower than in the sham operated rats. At the same time, the activity of Na+K+-ATPase and succinate dehydrogenase in the "caval" rats increased in the cells of the proximal tubule, diminished in Henle's loop, and remained unchanged in the cells of the distal convoluted tubule. Comparison of the results of functional and cytochemical study of the kidneys in caval rats allows the conclusion that intensified proximal reabsorption may be the main cause of antinatriuresis in these animals. The lesser load experienced by the distal segment promotes fuller reabsorption of sodium in this part of the nephron too.
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PMID:[Kidney function and Na+-K+-ATPase and succinate dehydrogenase activity in the cells of the renal tubules of rats with constriction of the thoracic portion of the vena cava inferior]. 21 36

Parathyroid hormone (PTH) decreases the transepithelial transport of Na+ in the proximal tubule, an action ascribed to PTH-inhibited apical Na(+)-H+ exchanger-dependent Na+ entry. We tested the possibility that PTH could also diminish Na(+)-K(+)-ATPase-dependent Na+ exit. To dissociate effects on Na+ entry, studies were performed in a suspension of rat proximal tubules by measuring nystatin-stimulated ouabain-inhibitable O2 consumption (QO2) and monensin-stimulated ouabain-sensitive 86Rb uptake in the absence or presence of bovine PTH-(1-34) fragment. PTH inhibited the percent nystatin-stimulated QO2 in a concentration-dependent manner, with maximal effect at 10(-10) M. PTH-increased cAMP formation was seen at doses higher than 10(-9) M and was maximal at 10(-7) M. Dibutyryl cAMP (10(-4) M) only partially reproduced the PTH action on QO2. Angiotensin II (10(-6) M) blunted the effect of 10(-7) M PTH on QO2, although it did not change 10(-7) M PTH-dependent cAMP generation. The analogues PTH-(3-34) and [Nle8,Nle18,Tyr34]PTH-(3-34)-amide mimicked the effects of PTH-(1-34) on QO2 but did not affect cAMP formation. Monensin-stimulated ouabain-sensitive 86Rb uptake was inhibited by PTH in a dose-dependent manner, with 10(-7) M PTH being maximally inhibitory. Na(+)-K(+)-ATPase activity was also decreased by PTH-(3-34) in a concentration-dependent manner, with maximal effect occurring at 10(-8) M. Agonist-dependent inhibition of Na+ pump was not due to a decrease of mitochondrial activity, because mitochondrial uncoupled QO2 rates were the same in control and PTH-treated tubules.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Parathyroid hormone inhibits proximal tubule Na(+)-K(+)-ATPase activity. 131 22

Brush-border (BBMV) and basolateral membrane vesicles (BLMV) from rat renal cortex exhibit an ecto-ATPase activity that is distinct from other ATPases. We have examined the cellular and regional distribution of this enzyme in rat kidney using antibodies against rat liver ecto-ATPase. In isolated vesicles, the distribution shown by biochemical assays of ATPase activity was confirmed by immunocytochemistry and Western blotting. Indirect immunofluorescence and immunogold labeling showed that brush borders of the S1 and S3 segments of the proximal tubule (PT) were stained, but the S2 segment was negative. Staining was most intense in the S3 segment. The luminal membrane of the initial part of the thin descending limb of Henle also showed a marked staining. Surprisingly, basolateral plasma membranes of PT had no detectable staining. However, the plasma membrane of endothelial cells was heavily stained, both in larger vessels and in peritubular capillaries. Using an antibody against rat thrombomodulin, a marker for endothelial cell plasma membranes, we showed that preparations of BBMV, BLMV, and endocytic vesicles are all contaminated with these membranes. This may explain, at least partially, the biochemically measured ecto-ATPase activity in renal cortical membrane vesicles. Finally, no specific staining in the kidney was found using polyclonal antipeptide antibodies against the "long form" of liver ecto-ATPase, either by immunocytochemistry or by Western blotting. This indicates either that there is no long isoform of the ecto-ATPase in the kidney or that the intracellular domains of the long form are different in the two tissues.
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PMID:Localization of ecto-ATPase in rat kidney and isolated renal cortical membrane vesicles. 131 23


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