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

Dog pancreatic tissue, incubated in a modified Wachstein-Meisel medium, showed two different adenosine triphosphatase activities. One of them is located at the apical border of the cells lining the intralobular ducts and of the centroacinar cells and is stimulated by HCO3-, depressed by SCN- and OCN- and completely abolished by CN-. The other is located at the intracellular clefts of the epithelium lining the interlobular ducts and is stimulated by Mg++. These findings correlate well with the results of incubation of homogenates of fresh and fixed tissues. Their significance with respect to the role of different segments of the duct system in the formation of the pancreatic juice is discussed.
 ...
PMID:Cytochemical study of the distribution of adenosine triphosphatase in the pancreas of the dog. 13 6

Microsomal fractions from homogenates of pig gastric fundic mucosa showed high levels of K+-stimulated adenosine triphosphatase (ATPase) and K+-stimulated phosphatase. Similar preparations from antral mucosa showed virtually no such activity. Because of mitochondrial contamination the fundic microsomes were further separated by sucrose density gradient centrifugation. A low density band of membranes (peak 1.12 to 1.13 g per ml) possessed all of the K+-stimulated enzyme activities. Morphological features and the abundant glycoproteins of the low density microsomes suggested they might be derived from the tubulovesicles of oxyntic cells. Mitochondrial and ribosomal markers were associated with membranes with much higher densities (greater than 1.22). The K+-stimulated ATPase has a pH optimum of 7.5 and required Mg++, but neither Na+ nor ouabain had any appreciable effect on the activity. Stimulation of basal ATPase by K+ ranged from 1.5 to 3.0-fold with an apparent Ka for activation between 0.2 to 0.4 mM K+. Addition of various K+ ionophoretic substances (e.g., gramicidin) produced further stimulation of K+-ATPase up to 6 times the basal rate. The mean activities for seven separate preparations of purified low density pig fundic microsomes were as follows (micromoles of ATP hydrolyzed per mg protein per hr +/- SEM); basal ATPase, 15.8 +/- 2.8; plus 10 mM K+, 29.3 +/- 4.5; plus 10 mM K+ and 10(-5) M gramicidin, 45.2 +/- 5.2. Neither the basal ATPase nor the K+-stimulated rates were altered by HCO3- or Cl-. The occurrence of these active and unique enzyme activities in the oxyntic region of gastric mucosa suggest some relation with secretory activity. Possible functional roles are discussed.
 ...
PMID:Unique enzymes of purified microsomes from pig fundic mucosa. K+-stimulated adenosine triphosphatase and K+-stimulated pNPPase. 23 96

1. We have measured cation transport in vivo in seven healthy volunteers under control conditions and after they had taken lithium carbonate for 21 days in doses which maintained the serum lithium concentration in the range 0.6-0.8 mmol/l. 2. We have measured cation transport in vivo after the administration of an oral load of rubidium chloride, and have found that, although intra-erythrocytic concentrations of rubidium were significantly lower 1 h after the administration of rubidium when the subjects were taking lithium, there was a significant increase in the rate of uptake of rubidium into the erythrocytes over the subsequent period of the test, suggesting a direct stimulation of sodium, potassium-activated adenosine triphosphatase by lithium. 3. Lithium administration did not affect the plasma concentration versus time profile of rubidium after the rubidium load, implying that the lithium-stimulated uptake of rubidium which occurs in erythrocytes does not necessarily occur in other cell types. 4. These results suggest that previous studies of cation transport using peripheral cells and assay systems in vitro do not necessarily reflect changes in cation transport in vivo in excitable tissues.
 ...
PMID:Measurement of cation transport in vivo in healthy volunteers after the oral administration of lithium carbonate. 254 Sep 32

Many 8-[(2-benzimidazolyl)sulfinylmethyl]-1,2,3,4-tetrahydroquinolin e derivatives were synthesized and tested for their (H+ + K+)adenosine triphosphatase (ATPase)-inhibitory and antisecretory activities against histamine-induced gastric acid secretion in rats. These sulfinyl compounds were synthesized by the oxidation of the corresponding sulfides, which were obtained from the reaction of 8-chloromethyl-1,2,3,4-tetrahydroquinolines and 2-mercaptobenzimidazoles in the presence of potassium carbonate. All compounds tested were potent inhibitors of (H+ + K+)ATPase. Most of the compounds showed antisecretory activity. Among them, 8-[(2-benzimidazolyl)sulfinylmethyl]-1-ethyl-1,2,3,4-tetrahydro quinoline (IXa) was found to have the most potent activity. The structure-activity relationships are discussed.
 ...
PMID:Studies on proton pump inhibitors. II. Synthesis and antiulcer activity of 8-[(2-benzimidazolyl)sulfinylmethyl]-1,2,3,4-tetrahydroquinolines and related compounds. 255 64

1. To test the hypothesis that NaCl increases blood pressure, while NaHCO3 does not, we measured the effect of an NaHCO3-containing mineral water on blood pressure in stroke-prone spontaneously hypertensive (SHR-SP) and Wistar-Kyoto (WKY) rats. We compared mineral water with equimolar amounts of NaCl and demineralized drinking water in six groups of 20 rats each over 24 weeks. 2. NaCl consistently increased blood pressure in both SHR-SP and WKY compared with demineralized water, while mineral water did not. 3. We studied the possible role of sodium-regulating hormones. Sodium, potassium-dependent adenosine triphosphatase activity was decreased by NaCl and by age, but not by mineral water. The concentration of atrial natriuretic peptide was greater in SHR-SP, but was not influenced by the two regimens. Components of the renin-angiotensin-aldosterone system and 18-hydroxydeoxycorticosterone tended to decrease with NaCl, but not with mineral water. 4. Plasma pH values in the six groups of rats were not different; however, SHR-SP had consistently lower PCO2 and HCO3- values and higher anion gap values than WKY rats. These values were not influence by the two regimens. 5. NaCl elevates blood pressure in SHR-SP while NaHCO3 does not. The changes in hormones regulating sodium homoeostasis suggest that NaCl induces volume expansion while NaHCO3 does not. The effect may be related to influences on renal sodium reabsorption by chloride and bicarbonate. The possible role of increased proton excretory activity in SHR-SP remains to be determined.
 ...
PMID:Effect of sodium chloride and sodium bicarbonate on blood pressure in stroke-prone spontaneously hypertensive rats. 284 Feb 35

Red blood cell Na+, K+-, Mg2+-, and Ca2+-adenosine triphosphatase (ATPase) activities were studied longitudinally in eight patients with affective disorders and 12 healthy volunteers. The patients had a higher mean Ca2+-ATPase activity than the volunteers, and the fluctuations in all three ATPase activities were greater in the patients than in the volunteers. Even though the mean Ca2+-ATPase activity was higher during manias and euthymic periods than during depressions, mood and ATPase activities did not correlate with each other in all patients. Lithium carbonate treatment did not alter the ATPase activities, and the quantity of vanadium present in the membranes could not account for the variations in the enzyme activities observed. We suggest that either the RBCs of manic-depressive patients are very sensitive to fluctuations of a lipophilic ATPase activity--regulating factor present in plasma or the patients have at times high levels of such a factor. In some patients, the level of this hypothesized regulator may fluctuate in synchrony with mood changes.
 ...
PMID:RBC membrane adenosine triphosphatase activities in patients with major affective disorders. 613 2

Much evidence shows that glia regulates the cation and anion content of brain interstitial space. In rats the pH and bicarbonate (HCO3-) concentration of neurons and glia were derived from carbon 14-labeled HCO3- and dimethyloxazolidinedione uptake into brain and cerebrospinal fluid. Acetazolamide increases the total CO2 concentration in neurons and decreases the pH and HCO3- concentration in glia. Inhibition of glial carbonic anhydrase (CA) reduces conversion of neuronally derived CO2 to HCO3-, glial pH is lowered, and neuronal CO2 accumulates. CA therefore has an essential role in regulating pH in neurons, glia, and interstitial fluid. In audiogenic seizure mice, glial CA activity is increased and glial anion transport is reduced. As the mice age, seizure susceptibility, the increased CA activity, and the defect in anion transport disappear concurrently. The enhanced CA activity in the glial cells of these mice is an adaptive mechanism to overcome the defect in anion transport that results from a deficiency of HCO3- -dependent and Na+- and K+ -dependent adenosine triphosphatase. Pentylenetetrazol stimulates neurons in neonatal rats, but after 10 days of age, when glia is present, it too is stimulated and the seizures are attenuated. Cobalt implantation in the cortex of rats also induces a glial response that ameliorates the focal seizures produced by this procedure.
 ...
PMID:Ionic and acid-base regulation of neurons and glia during seizures. 615 Jun 82

Sodium- and potassium-dependent adenosine triphosphatase (Na+--K+-ATPase) is demonstrated in the branchial heart of Sepia officinalis L. by biochemical, cytochemical and autoradiographical methods. The biochemical data indicate the presence of Na+--K+-ATPase, shown by potassium and magnesium dependency and inhibition by ouabain. Cytochemically and autoradiographically, the enzyme is localized in the sarcolemma of the muscle cells. The positive reaction of the transparent cells (type I cells) is due to activity of alkaline phosphatases. The dark cells (type II cells) react negatively. In addition to the Na+--K+-ATPase, a magnesium-activated adenosine triphosphatase (Mg2+-ATPase) and a bicarbonate-stimulated ATPase (HCO3(-)-ATPase) are localized in the mitochondria.
 ...
PMID:Adenosine triphosphatase localization in the branchial heart of Sepia officinalis L. (Cephalopoda). 625 31

Exposure of isolated gastric mucosal surface cells to NH4+ results in acidification of cells as determined by a fluorescent dye technique using acridine orange. The resulting intracellular pH gradient is maintained when cells are suspended in either buffered HCO3- -free Ringer's or choline chloride solution. Cells suspended in a Na+-containing but K+-free solution exhibit dissipation of the proton gradient. When Na+ is added to cells suspended in Na+, K+-free solution, the gradient rapidly dissipates with a half-maximal response occurring at 56 mM Na+. The effect of Na+ is amiloride sensitive with half-maximal inhibition occurring at 38 microM at a Na+ concentration of 50 mM. The K+ does not cause dissipation of the gradient and neither ouabain nor valinomycin have an effect. Yet, K+ has a modulating influence on Na+/H+ exchange by the isolated surface cells. The addition of K+ to acid-loaded cells resuspended in Na+-free solution decreases the ability of subsequent Na+ addition to evoke gradient dissipation. The data suggest that Na+/H+ exchange appears to be at least one mechanism whereby gastric mucosal surface cells could protect themselves against diffusing acid. This ion exchange mechanism is amiloride sensitive and appears to be unrelated to Na+, K+ adenosine triphosphatase activity, but is affected by the external K+ concentration.
 ...
PMID:H+ disposal by rabbit gastric mucosal surface cells. 669 70

The mechanism(s) for uptake of organic cations by renal cortical tubules was (were) examined further. Renal cortical tubules were purified from rat kidneys by a Percoll gradient centrifugation technique. Bicarbonate buffer (Krebs-Henseleit, KHS) conditions were altered, and chemical modulators were used which affect the activity of the basolateral Na+/K+-ATPase. Renal tubule uptake of the achiral organic cation amantadine was determined. The cardiac glycosides digoxin and acetylstrophanthidin and ouabagenin did not alter amantadine uptake by either proximal or distal tubule fragments in KHS. However, ouabain inhibited proximal tubule amantadine uptake in a dose-dependent manner with lower potency than distal tubule amantadine uptake in KHS. Ouabain did not inhibit amantadine tubule uptake in phosphate buffer. However, inhibition of amantadine uptake by ouabain returned in a time-dependent manner upon addition of bicarbonate to the phosphate buffer. Low extracellular sodium or potassium did not alter amantadine uptake by proximal tubules. Hypokalemic and hypokalemic/ hyponatremic conditions decreased the inhibitory potency of ouabain for amantadine uptake by proximal tubules. For distal tubules, both hyponatremic and hypokalemic conditions, alone and together, decreased the inhibitory potency of ouabain, but did not affect amantadine uptake in the absence of ouabain. Hypochloremic conditions decreased affinity for amantadine uptake by distal, but not proximal tubules. No change in maximal transport capacity for amantadine uptake was observed under hypochloremic conditions for either tubule fragment. These studies challenge the widely accepted concept of Na+/ K+-adenosine triphosphatase activity and maintenance of the basolateral membrane potential as rate-limiting steps for the energy-dependent renal tubule uptake of organic cations. Furthermore, these studies suggest a mechanism for ouabain inhibition of organic cation renal tubule uptake that may not involve the Na+/K+-adenosine triphosphatase and may be possibly bicarbonate-dependent.
 ...
PMID:Use of digitalis glycosides to identify the mechanisms of amantadine transport by renal tubules. 866 77


1 2 Next >>