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)

The influence of mixtures of taurocholate (TC), oleic acid (OA), caprylic acid (CA), and monolein (MO) on the toxic effects of deoxycholate (DC) in rat jejunum have been investigated using both a closed loop and perfusion technique. DC induced net secretion of water and electrolytes, inhibited glucose transport and transmural potential difference (PD), and inactivated mucosal "total" and (Na+ -K+)-adenosine triphosphatase. Secretion was reversed to absorption when the instilled or perfused solutions were composed of mixtures of DC, TC and OA; substitution of MO or CA for OA produced a similar effect. DC-induced inhibition of PD, glucose absorption, and mucosal adenosine triphosphatase activity was abolished when DC was mixed with TC and OA. Oleic acid emulsions had no effect on secretion induced by DC. Absorption of DC was inhibited from mixed micellar solutions (TC, OA, DC) but not from pure micellar solutions (TC, DC). These results indicate that the presence of taurocholate and fatty acids or monolein within the intestinal lumen markedly modify a number of the toxic effects of DC on jejunal function. The clinical effects of DC on intestinal function in man may therefore depend on the relative concentrations of other bile salts and lipids within the intestinal lumen.
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PMID:Influence of mixtures of taurocholate, fatty acids, and monolein on the toxic effects of deoxycholate in rat jejunum in vivo. 12 13

Sodium and potassium adenosine triphosphatase ((Na + K)-ATPase) consists of two polypeptides, a large molecular weight polypeptide (MW 84,000 to 102,000) and a sialoglycoprotein (MW 35,000 to 57,000). Trypsin treatment of this complex selectively cleaves the large polypeptide into two fragments with molecular weights of 62,000 and 43,000. Simultaneously with the appearance of these fragments, (Na + K)-APTase activity is destroyed. Trypsin treatment of phosphorylated enzyme shows that he 43,000 molecular weight fragment is phosphorylated. If (Na + K)-ATPase is digested with trypsin in the presence of ATP, a 90,000 molecular weight fragment is produced. Disappearance of the large polypeptide, and loss of ATPase activity parallel the production of this fragment. Addition of strophanthidin to this mixture significantly lowers the amount of the 90,000 molecular weight fragment produced. Experiments on (Na + K)-ATPase of the red cell membrane suggest that trypsin is cleaving (Na + K)-ATPase at the interior surface of the plasma membrane.
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PMID:Native (Na-+ + K-+)-dependent adenosine triphosphatase has two trypsin-sensitive sites. 12 78

A series of compounds related to 3-deoxydigitoxigenin was prepared and assayed for inhibition of myocardial Na+,K+- adenosine triphosphatase. Although the relatively high activity of 3-deoxydigitoxin was confirmed, the corresponding 3beta,4beta-epoxide and a mixture of 2,3-olefins and 3,4-olefins were less active. 3-Deoxy compounds with variations at the 14-position and the butenolide ring were much less active than the corresponding 3beta-hydroxy analogs. Thus the activity of 3-deoxydigitoxigenin appears to be particularly susceptible to structural changes elsewhere in the molecule.
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PMID:Cardiotonic steroids II: 3-deoxycardenolides and 3-deoxycardanolides. 12 24

The purpose of this work was to test the previously suggested hypothesis that the inhibitory effect of ouabain on lactate production in human red cells is due to an interaction between phosphoglycerate kinase and (Na+ + k+)-activated adenosine triphosphatase (Na+,K+ATPase). An antibody to red cell phosphoglycerate kingase caused complete inhibition of the purified enzyme, whereas a portion of the phophoglycerate kinase activity of the red cell membranes was resistant to the antibody. When increasing amounts of the purified enzyme were added to the membranes, the antibody-resistant portion of the activity increased. The effects of the antibody and ouabain on lactate production from fructose-6,6-diphosphate in red cell hemolysates were studied. Ouabain, at a maximally effective concentration, produced about 30% inhibition of lactate formation. This value was doubled in the presence of the antibody. Red cell membranes, and rat brain Na+,K+-ATPase, did not catalyze the hydrolysis of 1,3-diphosphoglycerate. Ouabain did not affect the reactions of the Rapport-Luebering pathway of the red cells. These findings provide further support for the view that in red cells a membrane pool of phosphoglycerate kinase is oriented in the vicinity of Na+,K+-ATPase in a way that the product of each enzyme may be used as the immediate substrate of the other and that ouabain inhibits glycolysis by removing the regulatory effect of Na+,K+-ATPase on that portion of glycolysis which is channeled through this pool of phosphoglycerate kinase.
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PMID:Studies on the mechanism of inhibition of the red cell metabolism by cardiac glycosides. 12 26

In chronic cobalt-induced experimental epilepsy in the cat, there are alterations in behavior, electroencephalograms, and brain sodium, potassium adenosine triphosphatase (Na,K ATPase) activity. The electrographic and enzymatic changes occur both in focus and homotopic cortex, and are time related. The onset of EEG paroxysms consistently precedes increases in Na,K ATPase activity, indicating that the enzymatic change is adaptive. Prophylactic treatment with phenytoin (formerly diphenylhydantoin) prevents these chronic alterations from developing, although some early changes do occur. After the drug is withdrawn following 28 days of therapy, treated animals still demonstrate no evidence of epileptiform discharges or changes in Na,K ATPase activity, although these changes persist in untreated cats. Given properly, phenytoin may prevent alterations in brain, which can result in the formation of a hyperexcitable population of cells. These data support the efficacy of early pharmacologic prophylaxis in posttraumatic epilepsy.
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PMID:Prophylactically administered phenytoin. Effects on the development of chronic cobalt-induced epilepsy in the cat. 12 75

An abnormal flux of monovalent cations may be related to the epileptogenic process in man. One possible mechanism for deranged electrolyte metabolism in epileptic brain is an abnormality in sodium, potassium-dependent adenosine triphosphatase (Na, K ATPase). We found the activity of Na, K ATPase to be significantly less in epileptic human corfex than in nonepileptic cortex. Histological changes have been simultaneously evaluated in epileptic brain. A second membrane-bound enzyme, acetylcholinesterase (AChE), was also assayed as a marker for neuronal membranes and found not to correlate with the epileptogenicity of human brain. In addition, the concentrations of the anticonvulsant compound phenytoin have been determined in the serum and cerebral cortex of epileptic and nonepileptic patients. The ratio of phenytoin in cortex to serum concentration is significantly lower in epileptic patients than in nonepileptic controls.
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PMID:Human epileptic brain Na, K ATPase activity and phenytoin concentrations. 12 76

Vesicles containing a purified shark rectal gland (sodium + potassium)-activated adenosine triphosphatase-(NaK ATPase) were prepared by dialyzing for 2 days egg lecithin, cholate, and the NaK ATPase purified from the rectal gland of Squalus acanthias. These vesicles were capable of both Na+ and K+ transport. Studies of K+ transport were made by measuring the ATP-stimulated transport outward of 42K+ or 86Rb+. Vesicles were preloaded with isotope by equilibration at 4 degrees for 1 to 3 days. Transport of 42K+ or 86Rb+ was initiated by addition of MgATP to the vesicles. The ATP-dependent exit of either isotope was the same. Experiments are presented which show that this loss of isotope was not due to changes in ion binding but rather due to a loss in the amount of ion trapped in the vesicular volume. The transport of K+ was dependent on external Mg2+. CTP was almost as effective as ATP in stimulating K+ transport, while UTP was relatively ineffective. These effects of nucleotides parallel their effects on Na+ accumulation and their effectiveness as substrates for the enzyme. Potassium transport was inhibited by ouabain and required the presence of Na+. The following asymmetries were seen: (a) addition of external Mg2+ supported K+ transport; (b) ouabain inhibited K+ transport only if it was present inside the vesicles; (c) addition of external Na+ to the vesicles stimulated K+ transport. External Li+ was ineffective as a Na+ substitute. The specific requirement of external Na+ for K+ transport indicates that K+ exit is coupled to Na+ entry. Changes in the internal vesicular ion concentrations were studied with vesicles prepared in 20 mM NaCl and 50 mM KCl. After 1 hour of transport at 25 degrees, a typical Na+ concentration in the vesicles in the presence of ATP was 72 mM. A typical K+ concentration in the vesicles was 10 mM as measured with 42K+ or 6 mM as measured with 86Rb+. The following relationships have been calculated for Na+ transport, K+ transport and ATP hydrolysis: Na+/ATP = 1.42, K+/ATP =1.04, and Na+/K+ = 1.43. The ratio of 2.8 Na+ transported in to 2 K+ transported out is very close to the value reported for the red cell membrane. Potassium-potassium exchange similar to that observed in the red cell membrane and attributed to the Na+-K+ pump (stimulated by ATP and orthophosphate and inhibited by ouabain) was observed when vesicles were prepared in the absence of Na+. The results reported in this paper prove that the shark rectal gland NaK ATPase, which is 90 to 95% pure, is the isolated pump for the coupled transports of Na+ and K+.
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PMID:Active potassium transport coupled to active sodium transport in vesicles reconstituted from purified sodium and potassium ion-activated adenosine triphosphatase from the rectal gland of Squalus acanthias. 12 52

Sodium-potassium-activated adenosine triphosphatase (Na-K-ATPase) is associated with electrolyte transport in many tissues. To help delineate its role in intestinal transport, changes in rat intestinal electrolyte and water transport induced by injecting methylprednisolone acetate 3 mg/100 g or deoxycorticosterone acetate (DOCA) 0.5 mg/100 g per day for 3 days were correlated with changes in Na-K-ATPase activity. Methylprednisolone increased sodium and water absorption, potassium secretion, transmural potential difference, and Na-K-ATPase activity in the jejunum, ileum, and colon. Examination of isolated epithelial cells demonstrated that the jejunal and ileal increase in Na-K-ATPase occurred in both the villus tip and crypermeability, Mg-ATPase, and adenylate cyclase activities were unchanged by methylprednisolone. DOCA increased sodium and water absorption, potassium secretion, transmural potential difference, and Na-K-ATPase activity in the colon alone. Colonic Mg-ATPase and adenylate cyclase activities were unaffected. Jejunal and ileal enzyme activity, electrolyte transport, and permeability were unchanged by DOCA. Methylprednisolone and DOCA were not additive in their effect on colonic Na-K-ATPase activity. Methylprednisolone and DOCA increased electrolyte and water transport and Na-K-ATPase activity concomitantly in specific segments of small intestine and colon. These data are consistent with an important role for Na-K-ATPase in intestinal electrolyte and water transport.
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PMID:Na+-K+-activated adenosine triphosphatase and intestinal electrolyte transport. Effect of adrenal steroids. 12 64

Sodium and potassium ion-activated adenosine triphosphatase is the enzyme responsible for the active transport of sodium and potassium across the plasma membrane. Strophanthidin, from the external surface of the membrane, and an antibody, from the cytoplasmic surface, bind simultaneously to the large polypeptide subunit of the enzyme. These results demonstrate that this polypeptide chain must span the plasma membrane, having different surfaces exposed on each side. When (Na+ + K+)-ATPase is incubated in the presence of cupric phenanthroline, a reagent which catalyzes the oxidation of cysteine residues to form intermolecular and intramolecular disulfide bonds, a covalent dimer of the larger chains is formed. Several characteristics of this dimerization reaction are consistent with the proposal that at least a noncovalent dimer of large chains exists in the native enzyme. These conclusions are discussed in the context of a specific description for the molecular mechanism of active transport.
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PMID:Structural studies of sodium and potassium ion-activated adenosine triphosphatase. The relationship between molecular structure and the mechanism of active transport. 12 37

Acute starvation of adult rats resulted in a rise in the electroconvulsive threshold at 48 hours (P less than .10) and at 72 hours (P less than .01), but not at 24 hours. Biochemical correlates included (1) ketonemia and mild hypoglycemia in the blood; (2) a significant rise in the brain cytoplasmic phosphorylation potential and in the energy charge potential; (3) a shift in the brain cytoplasmic oxidation-reduction potential to a more oxidized state; (4) probable partial inhibitions in brain phosphofructokinase and pyruvate dehydrogenase; and (5) relatively small increases in brain sodium (4.1%), potassium (2.4%), and chloride (4.3%). No major differences were seen in brain water content or adenosine triphosphatase activity. The observed cerebral biochemical alterations are believed to be the consequence of increased ketone body utilization, although the precise relationship to the alteration in the electroconvulsive threshold remains unclear.
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PMID:Starvation and seizures. Observation on the electroconvulsive threshold and cerebral metabolism of the starved adult rat. 12 78


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