Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Studies conducted into the activity of adenosine triphosphatase (ATPase) in homogenate of several tissues of sheep and against the background of pH 7.5 (tris-HCl buffer) have shown highest enzyme activity to develop in renal cortex and cerebral cortex followed, in declining order of quotation, by liver, myocardium, and mucous membrane of small intestine. ATPase activities were studied also in the presence of pH-values between 7.2 and 8.95 (tris-HCl buffer) and between 8.6 and 11 (piperazine buffer), with the pH optimum of ATPase in the above tissues having been found to lie at approximately 9.0. Different concentrations of Mg ions were added, and maximum ATPase activity of 2 mMol ATP was obtained by adding 2 mMol Mg. Decline in ATPase activity should be expected in the case of hypomagnesaemia. Addition of different concentrations of sodium and potassium ions gave in most of the tissues tested maximum activity in response to 10 mMol potassium and 68 mMol sodium. Na-K ATPase could be inhibited by oubain particularly in cerebral and renal cortex.
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PMID:[Activities and properties of adenosine triphosphatase (ATPase) in homogenates of renal cortex, liver, myocardium and small-intestine mucosa in sheep]. 13 80

The mechanism of stimulatory action of histamine on gastric alkaline secretion was investigated in anesthetized rats. Intravenous infusion of histamine (2-8 mg/kg/hr) dose-dependently stimulated acid secretion and in the presence of omeprazole (60 mg/kg), an H+/K+-adenosine triphosphatase inhibitor, produced an increase of gastric but not duodenal alkaline secretion; the degree of gastric alkalinization was also dependent on the dose of histamine, reaching the maximal values of approximately 1.0 microEq/10 min. Cimetidine (100 mg/kg s.c.) significantly inhibited both acid and alkaline secretory responses caused by histamine, whereas indomethacin (5 mg/kg s.c.) significantly prevented the increased alkaline secretion caused by histamine as well as mucosal acidification (100 mM HCl for 10 min). Tripelennamine (10 mg/kg s.c.) had no effect on either acid or alkaline secretion. Histamine (8 mg/kg/hr) reduced the arterial blood pressure (25.3%) and increased the mucosal vascular permeability in the stomach as determined by Evans blue (160%), but these vascular responses were significantly prevented only by tripelennamine, excluding the possible contribution of the vascular effects to the increased gastric alkaline secretion. These results suggest that histamine may stimulate gastric alkaline secretion as well as acid secretion, and the mechanism of histamine-induced alkaline secretion may involve both endogenous prostaglandins and stimulation of H2-receptors.
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PMID:Stimulation of gastric alkaline secretion by histamine in rats: possible involvement of histamine H2-receptors and endogenous prostaglandins. 291 81

1. We have isolated a mutant of Escherichia coli K12 (strain AN295) that forms de-repressed amounts of Mg(2+),Ca(2+)-stimulated adenosine triphosphatase. 2. The Mg(2+),Ca(2+)-stimulated triphosphatase activity was separated from membrane preparations from strain AN295 by extraction with 5mm-Tris-HCl buffer containing EDTA and dithiothreitol, resulting in a loss of the ATP-dependent transhydrogenase activity. The non-energy-linked transhydrogenase activity remained in the membrane residue. 3. The solubilized Mg(2+),Ca(2+)-stimulated adenosine triphosphatase activity from strain AN295 was partially purified by repeated gel filtration. The addition of the purified Mg(2+),Ca(2+)-stimulated adenosine triphosphatase to the membrane residue from strain AN295 reactivated the ATP-dependent transhydrogenase activity. 4. Strain AN296, lacking Mg(2+),Ca(2+)-stimulated adenosine triphosphatase activity, was derived by transducing the mutant allele, uncA401, into strain AN295. The ATP-dependent transhydrogenase activity was lost but the non-energy linked transhydrogenase was retained. 5. The ATP-dependent transhydrogenase activity in membrane preparations from strain AN296 (uncA(-)) could not be re-activated by the purified Mg(2+),Ca(2+)-stimulated adenosine triphosphatase from strain AN295. However, after extraction by 5mm-Tris-HCl buffer containing EDTA and dithiothreitol, the ATP-dependent transhydrogenase activity could be re-activated by the addition of the purified Mg(2+),Ca(2+)-stimulated adenosine triphosphatase from strain AN295 to the membrane residue from strain AN296 (uncA(-)).
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PMID:Reconstitution of the energy-linked transhydrogenase activity in membranes from a mutant strain of Escherichia coli K12 lacking magnesium ion- or calcium ion-stimulated adenosine triphosphatase. 426 1

In vivo ethanol exposure reduces in vitro Na+,K(+)-adenosine triphosphatase (Na+,K(+)-ATPase) sensitivity to ethanol in some animal models, but very little is known about the effects of ethanol on human brain Na+,K(+)-ATPase. Cerebral cortex homogenates from 13 male alcoholic and 9 control subjects were assayed for K(+)-p-nitrophenylphosphatase (K(+)-pNPPase, a measure of Na+,K(+)-ATPase) and Mg(2+)-pNPPase activities at 37 degrees for 20 min in 75 mM imidazole-HCl (pH 7.4), 5 mM p-nitrophenylphosphate, 5 mM MgCl2, and 20 mM KCl, with or without 1 mM ouabain. Native K(+)-pNPPase activites were similar in control and alcoholic brains (61.5 +/- 3.5 vs 55.3 +/- 3.1 nmol/mg/min). In vitro exposure to a near lethal ethanol level (0.5%, or 110 mM) was without effect, whereas 5% ethanol inhibited K(+)-pNPPase activity by about 28% (P < 0.001) in both groups. Both 0.5 and 5% ethanol in vitro significantly stimulated Mg(2+)-pNPPase activity (1-2% and 19-20%, respectively). By comparison, mouse brain K(+)-pNPPase was inhibited significantly by in vitro ethanol, and Mg(2+)-pNPPase activity was unaffected. Ethanol levels attainable in humans may not be sufficient to alter significantly brain Na+,K(+)-ATPase activity.
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PMID:Effects of in vitro ethanol on the brain cation pump in alcoholics and controls. 805 41

A rat glioma model was employed to estimate the Ca2+ kinetics in the tumor arteriolar smooth muscle cells. Electron microcytochemistry revealed that the density of intracellular Ca2+ deposits in the intra-tumor arteriolar smooth muscle cells was significantly greater, with slightly higher membrane Ca(2+)-adenosine triphosphatase (ATPase) activity, compared to the contralateral cerebral arterioles. Furthermore, the administration of tyrphostin, a tyrosine kinase inhibitor, specifically increased only the intra-tumor blood flow. These findings suggest that the condition of the intra-tumor arteriole alters the susceptibility to contraction by the accelerated Ca2+ influx into the cytoplasm mediated through the tyrosine kinase pathway. After the administration of diltiazem, which also has a blocking effect on the Ca(2+)-channel mediated through this pathway, the local intra-tumor blood flow showed an increase of 39% with a marked decrease of intracellular Ca2+ concentration of the arteriolar smooth muscle cells in the tumor, while the blood flow in the basal ganglia increased by only 8%. The intra-tumor concentration of Nimustine-HCl (ACNU) with co-administration of diltiazem was significantly increased compared to that without the co-administration. Co-administration of diltiazem may be a valuable strategy in chemotherapy for glioma in affording the selective increase of intra-tumor concentration of the anti-cancer drug.
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PMID:A strategy for selective anti-cancer drug concentration increase in rat glioma tissue with Ca(2+)-channel blocker co-administration: calcium kinetics in intra-glioma arteriolar smooth muscle cells. 886

Amidated and nonamidated progastrin-derived peptides have distinct biological activities that are mediated by a range of receptor subtypes. The objective was to determine the nature of the stored and secreted progastrin-derived peptides and to investigate whether progastrin release is regulated by gastric acidity. Using an antiserum directed to the C terminus of progastrin for identification and to monitor purification, C-terminal flanking peptides (CTFP) of progastrin (prog(76-83), prog(77-83), and prog(78-83) in approximately equivalent amounts) were isolated and identified from extracts of sheep antrum using ion exchange, HPLC, and mass spectrometry. Only trace amounts of full-length progastrin were present. Progastrin CTFP was the predominant progastrin-derived peptide in the antrum [progastrin CTFP/gastrin amide (Gamide) = 3]. Similarly, progastrin CTFP was the major circulating form in the antral (CTFP, 710 +/- 62 pmol/liter; Gamide, 211 +/- 35 pmol/liter) and jugular (CTFP, 308 +/- 16 pmol/liter; gastrin amide, 32 +/- 3 pmol/liter) veins. Alteration of gastric acidity in sheep by iv infusion of a H/K-adenosine triphosphatase inhibitor or somatostatin or by intragastric infusion of HCl demonstrated that the CTFP concentrations changed, although to a lesser extent than the changes in circulating gastrin amide. We conclude that the CTFP of progastrin is the major stored and circulating species of the gastrin gene, and that it is secreted in a regulated fashion rather than constitutively. Because full-length progastrin is bioactive, but is only a minor antral and secreted form, determination of the biological activity of the C-terminal flanking peptides will be important for a complete understanding of gastrin endocrinology.
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PMID:Identity and regulation of stored and secreted progastrin-derived peptides in sheep. 1530 16