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)

Vacuolar H+ ATPases reside in the plasma membrane of several segments of the mammalian nephron. In the proximal tubule, H+ ATPase is located in both the brush-border microvilli and in subvillar invaginations, while in the collecting duct intercalated cells, it is primarily in plasmalemma-associated membranes. H+ ATPase isolated from bovine kidney brush border has a cluster of polypeptides of Mr greater than 31,000 found associated with the Mr = 31,000 subunit, whereas H+ ATPase isolated from microsomes dose not have the additional associated polypeptides (Wang, Z.-Q., and Gluck, S. (1990) J. Biol. Chem. 265, 21957-21965, 1990). In this study, we describe the production of several new monoclonal antibodies to the bovine vacuolar H+ ATPase Mr = 31,000 subunit. Two of the antibodies differed in reactivity to the cluster of Mr greater than 31,000 subunits found in purified bovine kidney brush-border H+ ATPase. Antibody E11 reacted with both the Mr = 31,000 and Mr greater than 31,000 subunits and stained renal brush border intensely. Antibody H8 did not react with the Mr greater than 31,000 polypeptides and did not stain brush border. The heterogeneity of the Mr greater than 31,000 subunits did not appear attributable to glycosylation or phosphorylation. These findings provide further evidence for heterogeneity of the Mr = 31,000 subunit in different renal membrane compartments and suggest a role for the Mr greater than 31,000 polypeptides specific to the brush-border microvilli.
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PMID:Immunologic evidence that vacuolar H+ ATPases with heterogeneous forms of Mr = 31,000 subunit have different membrane distributions in mammalian kidney. 153 41

Na-coupled D-glucose transport in rabbits with cis-diamminedichloride platinum (CDDP; cisplatin) induced acute renal failure (ARF) has been studied. ARF occurred at 3 days after injection of CDDP (3 mg/kg i.v.). Na-coupled D-glucose transport into brush-border membrane vesicles (BBMV) from both outer cortex (OC) and outer medulla (OM) of ARF rabbits under zero-trans condition was decreased. Increased Km (i.e., decreased affinity of transport carrier for D-glucose) in OC and decreased Vmax (i.e., decreased number of glucose carrier) in OM were observed in CDDP-induced ARF rabbits. Decrease glucose transport was also observed under equilibrium exchange condition. Intravesicular volume of BBMV from OC and OM of ARF rabbits was decreased. In homogenate and BBMV from OC and OM of ARF rabbits, activities of gamma-glutamyl transpeptidase and alkaline phosphatase (marker enzymes of brush-border membrane) were decreased. Activities of succinate dehydrogenase, glucose-6-phosphatase, and Na-K ATPase (marker enzymes of mitochondria, endoplasmic reticulum, and basal lateral membrane, respectively) were not affected by CDDP administration. These results suggested that one of the main target sites of CDDP in kidney is brush-border membrane (BBM) along the proximal tubule, that is, not only Na-coupled D-glucose transport carrier protein but also other proteins in BBM.
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PMID:Decreased sodium dependent D-glucose transport across renal brush-border membranes in cis-diamminedichloride platinum induced acute renal failure. 156 86

To determine whether growth hormone (GH) directly affects ammoniagenesis in the renal proximal tubule, ammonia production was measured in suspensions of isolated canine renal proximal tubule segments (IPTs) incubated with 2.5 mM L-glutamine and varying concentrations of human growth hormone (hGH). Ammonia production from IPTs significantly increased by nearly threefold in the presence of hGH (10(-6) M) at 60 min. This increase was dose dependent, with as little as 10(-9) M hGH significantly stimulating ammonia production. In addition, hGH enhanced glucose production when lactate, alanine, and succinate replaced L-glutamine as substrate. hGH significantly stimulated ammonia production when IPTs were incubated at alkalotic and neutral pH. The effect of hGH was lost at acidic pH. When hGH was added to IPTs incubated under Na(+)-equilibrated conditions, ammonia production was not different from control. hGH stimulated ouabain-sensitive Na(+)-K(+)-adenosinetriphosphatase (ATPase) activity by 8.1 +/- 1.1% in basolateral membranes isolated from IPTs. hGH stimulation of proximal tubule ammonia production from L-glutamine occurs at physiological concentrations of hGH and when the extracellular-to-intracellular Na+ gradient favors L-glutamine transport. This effect is associated with an increase in basolateral Na(+)-K(+)-ATPase activity. The data suggest a role for hGH in the regulation of renal acid-base metabolism under physiological conditions in which increased net acid excretion is important.
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PMID:Growth hormone regulates ammoniagenesis in canine renal proximal tubule segments. 159 Apr 30

Renal nerve activity increases (Na+, K+)-ATPase activity and contributes to the development of hypertension in young SHR. The present study was designed to examine the effect of sodium intake on blood pressure and proximal tubule solute reabsorption in sham-operated or renal denervated, 5-week old SHR and WKY. Three-week old SHR and WKY rats underwent sham surgery or renal denervation with 10% phenol and were maintained for 10 days on either a 0.6% or 2.2% NaCl diet. Blood pressure was obtained by indirect tail cuff measurements during this interval. Of the eight groups, only sham-operated SHR on a high sodium diet had hypertension, 122.0 +/- 4.2 mm Hg vs. 98.7 +/- 3.3 mm Hg (mean for remaining groups). Renal plasma flow (RPF), glomerular filtration rate (GFR), and the fractional excretion of lithium (FELi) were determined in rats maintained on a 2.2% sodium diet at 5 weeks of age. FELi was less in sham-operated SHR, 5.3 +/- 0.7%, compared to WKY, 9.4 +/- 2.8% (P less than 0.02). Furthermore, denervation ameliorated the reduced FELi in SHR, 10.2 +/- 1.2%, without affecting FELi in WKY. RPF and GFR were similar between sham-operated and renal denervated SHR and WKY. No significant difference could be detected in net sodium balance between WKY and SHR during this period. These findings demonstrate 1) from the basis of FELi, young SHR, of this strain, exhibit enhanced proximal tubule solute reabsorption and hypertension while on a high sodium diet and, 2) renal denervation ameliorates both the enhanced proximal tubule solute reabsorption and the early development of hypertension. These data support the concept that renal nerve activity of young SHR is augmented and contributes to the development of hypertension by enhancing salt retention.
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PMID:Renal nerve-mediated proximal tubule solute reabsorption contributes to hypertension in spontaneously hypertensive rats. 162 13

Single segments of rat nephron contain two distinct ouabain-insensitive, K-independent, Na-dependent ATPase activities: a Na-stimulated ATPase and a Na-inhibited ATPase. Na-inhibited ATPase activity is found in the proximal tubule and the thick ascending limb of Henle's loop but is absent in the collecting tubule whereas Na-stimulated ATPase is exclusively located in the proximal convoluted tubule. Na-inhibited ATPase, but not Na-stimulated ATPase, is totally abolished in the presence of 100 microM Ca2+. Conversely, Na-stimulated ATPase, but not Na-inhibited ATPase, is curtailed when nephron segments are preincubated at pH 7.2 whereas it is activated at pH 7.8. Finally, Na-stimulated ATPase displays an apparent Km for Na+ of approximately 10 mM, and is dose-dependently inhibited by the diuretic triflocin (IC50 approximately 6 x 10(-6) M).
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PMID:Characterization and localization of ouabain-insensitive Na-dependent ATPase activities along the rat nephron. 164 98

The technique for X-ray microanalysis of frozen-hydrated bulk specimens was used to determine the intracellular and luminal fluid electrolyte concentrations in the proximal tubules of kidneys from chickens infected with infectious bronchitis virus. Eight days post-infection with this virus there were significant changes in the electrolyte composition when compared with values from normal control chickens. The intracellular sodium decreased from 43 to 36 mmol/l, the chloride fell from 41 to 31 mmol/l and the potassium went from 125 to 115 mmol/l. Sodium counts in the luminal fluid rose from .73 to 1.03 cps. These disturbances in electrolyte composition are consistent with alterations in sodium reabsorption in the proximal tubule due to decreased transport of sodium into the cells across the microvillus membrane. It appears that the Na-K-ATPase pump is unaffected. The results demonstrate the value of X-ray microanalysis methods for the study of electrolyte transport in pathologically affected cells and provide further information for the definition of viral-host cell interactions in the pathogenesis of viral disease. As a check on methodology two normal rat kidneys were analysed in the same way. Intracellular sodium and potassium concentrations were 22 and 138 mmol/l respectively.
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PMID:X-ray microanalytical investigation of the response of chicken proximal tubule cells to infection with avian infectious bronchitis virus. 164 25

Na,K(+)-ATPase activity is decreased in homogenized renal tissue from GM-treated rats. This study examines whether the site of the active effect of GM on Na,K(+)-ATPase activity in the kidney can be localized to the proximal convoluted tubules (PCT) where the drug is taken up and where it will produce necrosis. In rats treated with gentamicin (50 micrograms.kg-1.day-1 i.m.) for 7 days, PCT Na,K(+)-ATPase activity was reduced as compared to vehicle-treated rats but returned to control levels 7 days after treatment withdrawal. In another nephron segment, the medullary thick ascending limb of Henle (mTAL), where GM induced lesions are uncommon, Na,K(+)-ATPase activity was the same in GM- and vehicle-treated rats treatment. To study the in vitro effect of GM, dissected PCT and mTAL segments from untreated rats were preincubated for 30 min with GM 10(-3) M, a dose similar to the tissue concentration in chronically treated rats. In tubule segments that were permeabilized to allow the drug to enter the cells, GM 10(-3) M significantly inhibited Na,K(+)-ATPase activity both in PCT and mTAL. In non-permeabilized mTAL segments GM did not inhibit Na,K(+)-ATPase activity. GM inhibition of Na,K(+)-ATPase activity in permeabilized PCT segments persisted after the tubules were rinsed in GM free medium. GM does not inhibit Na,K(+)-ATPase partly purified from the renal cortex. Conclusion. Gentamicin inhibits Na,K(+)-ATPase activity in renal tubule cells when it has access to the cytoplasm. Treatment with GM will therefore cause a selective inhibition of Na,K(+)-ATPase in the proximal tubule cells.
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PMID:Gentamicin inhibition of Na+,K(+)-ATPase in rat kidney cells. 164 25

The role of the mammalian mesonephric kidney is not completely understood. It has been established that outpouchings of the mesonephric excretory ducts give origin to parts of the urogenital system of the adult. It is also known that mammalian mesonephric urine is formed as an ultrafiltrate. The mesonephric renal tubules have Na+/K+ adenosine triphosphatase (Na+/K+ pump), secrete phenol red, and reabsorb protein. Prior to this work, the possibility of epithelial transport of ions and metabolic substrates across mammalian mesonephric tubules had not been directly evaluated. Proximal mesonephric tubules obtained from 17 to 18-days-old rabbit embryos were isolated and perfused in vitro. Continuous intracellular electrical recordings were obtained with Ling-Gerard-type microelectrodes and a high input impedance electrometer. In tubules perfused and bathed in standard mammalian Ringer's solutions, the average transmembrane electrical cell potential difference (PD) was -43 +/- 0.5 mV (76 cells). The cellular PD decreased by 30 percent when the temperature of the bath was cooled from 37 degrees C to 30 degrees C. The cells also depolarized by 25 percent in the first five minutes of exposure to 0.1 mM ouabain. In addition, the cell PD decreased by 40 and 60 percent when the extracellular potassium concentration was raised from five to 25 and 50 mM, respectively. The uptake of glucose and alanine was similarly electrogenic (delta:1 mV/mM). The cell PD, the K+ conductance, and the electrogenicity induced by luminal exposure to 5 mM glucose or alanine are significantly lower in the mesonephric as compared to the metanephric proximal tubules of the rabbit. These observations suggest that sodium-coupled transepithelial transport mechanisms, driven by the Na+/K+ pump, are already present in the mammalian mesonephric proximal tubule. Increases in the number of Na+/K+ pumps, conductive K+ channels, and sodium-substrate cotransporters seem to be at the core of proximal tubular ontogeny.
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PMID:Renal ontogeny: epithelial transport in the mammalian mesonephric proximal tubule. 164 30

In the present study, we used [3H]idazoxan and [3H]rauwolscine to characterize the imidazoline-guanidinium receptive site (IGRS) and alpha 2-adrenoceptors in the human renal proximal tubule, respectively. In purified basolateral membranes, 11-fold enriched in Na(+)-K+ ATPase. [3H]idazoxan and [3H]rauwolscine binding was twofold higher than in homogenates ([3H]idazoxan: 87 +/- 19 vs. 45 +/- 23.3 fmol/mg protein, P less than 0.05; [3H]rauwolscine: 56.4 +/- 21.4 vs. 25.2 +/- 7.3 fmol/mg protein, P less than 0.01). In competition studies performed at saturating concentration of [3H]idazoxan (15 NM), specific binding was competed for by epinephrine and rauwolscine only by 10-15% but was completely inhibited by imidazoline and guanidinium compounds. Thus, in human renal proximal tubule. [3H]idazoxan mainly binds to an IGRS. The highest density of alpha 2-adrenoceptors in basolateral membranes and of IGRS in partially purified membrane preparations, suggests that these two binding sites have a different subcellular localization. When compared to the rabbit renal IGRS, the human [3H]idazoxan binding site displays different affinities for guanabenz, rilmenidine, clonidine, amiloride and its derivatives that persist after membrane solubilization. In contrast, the human and rabbit renal IGRS share similar regulatory properties such as the sensitivity to K+ and the insensitivity to Na+, divalent cations and 5'-guanylylimidodiphosphate (Gpp(NH)p). In conclusion, we demonstrated that, in the human renal proximal tubule, alpha 2-adrenoceptors are mainly located in basolateral membranes while IGRS appear to be associated with another cell compartment. As indicated by their common interaction with imidazoline and guanidinium derivatives and by similar regulatory properties, human and rabbit IGRS belong to the same family of membrane proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Imidazoline-guanidinium and alpha 2-adrenergic binding sites in basolateral membranes from human kidney. 164 94

Establishment and maintenance of a polar distribution of Na+,K(+)-ATPase is essential for efficient Na+ reabsorption by proximal tubule cells and is dependent upon the formation of a metabolically stable, detergent-insoluble complex of Na+,K(+)-ATPase with the actin membrane cytoskeleton. The present studies show that cellular ATP depletion results in a rapid duration-dependent dissociation of Na+,K(+)-ATPase from the actin cytoskeleton and redistribution of Na+,K(+)-ATPase to the apical membrane. During ATP depletion, total cellular Na+,K(+)-ATPase activity was unaltered, but the Triton-X-100-insoluble fraction (cytoskeleton associated) of Na+,K(+)-ATPase activity decreased (P less than 0.01), with a corresponding increase in the detergent-soluble fraction of Na+,K(+)-ATPase (P less than 0.01). Indirect immunofluorescent studies of cells with depleted ATP revealed a redistribution of Na+,K(+)-ATPase from the basolateral membrane into the apical membrane and throughout the cytoplasm. ATP depletion also resulted in the redistribution of F-actin from a primarily cortical concentration to a perinuclear location. There was also a rapid, duration-dependent conversion of monomeric G-actin to F-actin starting during the first 5 min of ATP depletion. Taken together, these data suggest that ATP depletion causes profound alterations in cell polarity by inducing major changes in the actin cytoskeletal architecture.
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PMID:Dissociation and redistribution of Na+,K(+)-ATPase from its surface membrane actin cytoskeletal complex during cellular ATP depletion. 165 Jul 94


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