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)

Subcellular fractions in hearts from rats with severe acute uremia (24 hours after total nephrectomy) and moderate chronic uremia (2 weeks after five sixths nephrectomy) were studied and compared with preparations from acute and chronic sham-operated rats, respectively. Calcium- and magnesium-sensitive actomyosin adenosine triphosphatase (ATPase) activities were normal in both groups. Acute uremia was associated with a significant depression of sarcolemmal Na+,K+ ATPase activity. Calcium transport by fragmented sarcoplasmic reticulum was also depressed in the presence and absence of oxalate in acute uremia. Mitochondrial calcium transport and adenosine triphosphate (ATP) and creatine phosphate (CP) concentrations were normal in these animals. Chronic uremic animals showed no abnormal subcellular mechanisms. These data suggest a direct effect of acute uremia on some membrane functions in myocardial cells. The discrepancies observed between acute and chronic uremic groups may be due to a different degree of uremic state. The observation of depressed calcium transport by fragmented sarcoplasmic reticulum (FSR) in acute uremic hearts which were previously shown to have increased contractile reserve suggests that studies of calcium transport in FSR may not always truly reflect the contractile capacity of the heart.
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PMID:Studies of subcellular control factors in hearts of uremic rats. 13 36

Previous investigations have documented a reduced activity of the sodium-potassium-stimulated adenosine triphosphatase enzyme (Na+,K+ ATPase) in platelet membranes of allergic subjects. The purpose of this study was to determine if the reduced Na+,K+ ATPase activity was due to an enzyme inhibitor. Na+,K+ ATPase activity of a particulate fraction of sonicated platelets was determined by spectrophotometry in asymptomatic adults with and without allergy. The Na+,K+ ATPase level (mean, nanomoles per microgram of protein per minute; +/- STD) of allergic subjects (0.9 +/- 1.3) was lower (p less than 0.001) than that of nonallergic subjects (3.9 +/- 1.6). In contrast, when the same platelet fractions were frozen before assay, Na+,K+ ATPase was higher (p less than 0.005) in allergic subjects (6.0 +/- 1.4) than in nonallergic subjects (3.6 +/- 2.0). An inhibitor of canine kidney Na+,K+ ATPase was detected in the buffer in which these platelet fractions were frozen, allergic subjects (0.5% +/- 0.4% inhibition per microgram of protein) compared to nonallergic subjects (0.04% +/- 0.08%; p less than 0.005). The level of inhibition correlated positively with the postfreezing increase in platelet membrane Na+,K+ ATPase, suggesting a freezing-induced displacement of an inhibitor from the membrane. Plasma from these same subjects inhibited Na+,K+ ATPase activity of normal platelets, allergic subjects (70% +/- 31% inhibition) compared to nonallergic subjects (13% +/- 16%; p less than 0.001). These data suggest that the transport-enzyme defect observed in platelets from allergic subjects was due to a circulating Na+,K+ ATPase inhibitor. In vivo Na+,K+ ATPase inhibition in allergy could have profound effects on intracellular cation concentrations and broad implications for pathogenesis.
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PMID:A circulating inhibitor of the platelet Na+,K+ adenosine triphosphatase (ATPase) enzyme in allergy. 184 56

Previous studies have documented decreased levels of platelet sodium, potassium adenosine triphosphatase (Na+, K+ ATPase) enzyme activity in allergic subjects. The purpose of this study was to determine the effect of several drugs used to treat allergy and asthma on platelet Na+,K+ ATPase activity. Platelets from five allergic and five nonallergic subjects were incubated at 37 degrees C for 30 minutes with cortisol (1.0 to 3.6 micrograms/ml), theophylline (10 to 40 micrograms/ml), cromolyn (0.5 to 2.0 micrograms/ml), albuterol (3 to 24 ng/ml), chlorpheniramine (2.5 to 20 micrograms/ml), or diluent. The platelets were then rinsed, sonicated, serially centrifuged, and assayed for Na+,K+ ATPase activity nmol/min x micrograms protein by spectrophotometry. Mean activity (+/- 1 SEM) for the diluent incubation was 5.55 +/- 1.27 nmol/min x micrograms protein and 0.91 +/- 0.32 nmol/min x micrograms protein for the nonallergic and allergic subjects, respectively. The enzyme activity of allergic platelets (same units as above) increased after incubation with the following drugs: cortisol, 6.07 +/- 1.75 (p < 0.025) at 1.0 micrograms/ml, 7.55 +/- 1.36 (p < 0.005) at 1.4 micrograms/ml, and 5.95 +/- 0.91 (p < 0.025) at 1.8 micrograms/ml; cromolyn, 5.79 +/- 1.68 (p < 0.050) at 1.0 micrograms/ml; and albuterol, 4.43 +/- 1.61 (p < 0.05) at 12 ng/ml. Theophylline and chlorpheniramine did not have a similar effect on Na+,K+ ATPase activity. These data show that some of the drugs commonly used to treat allergic patients, especially anti-inflammatory agents, can increase the depressed platelet levels of Na+,K+ ATPase activity observed in allergic subjects. Modulation of Na+,K+ ATPase is a possible mechanism of action for these drugs in vivo.
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PMID:In vitro modulation of platelet sodium, potassium adenosine triphosphatase enzyme activity by antiallergy drugs. 839 60

Previous studies have documented the presence of a sodium, potassium adenosine triphosphatase (Na+,K+ ATPase) enzyme inhibitor on platelet membranes and in the plasma of patients with allergy, many of whom historically had airway hyperreactivity (AHR). The purpose of this study was to investigate the relationship between methacholine AHR and Na+,K+ ATPase enzyme inhibition. In the first experiment, 47 adult subjects (13 allergic, 5 potentially allergic, 12 asthmatic, and 17 control subjects) were tested for platelet membrane Na+,K+ ATPase inhibition and AHR. Area under the methacholine dose-response curve (AUC) was expressed as percent baseline FEV1 x log concentration of methacholine (log [mg/ml]) and plotted as a function of the difference in postfreezing and prefreezing platelet membrane Na+,K+ ATPase activities (reflective of membrane-bound inhibitor), which was expressed as nanomoles per microgram of protein per minute (nmol/microg protein/min). A significant (r = -0.44, p < 0.005) negative correlation between the two was detected, such that high levels of AHR (low AUC) were associated with high levels of membrane-bound inhibitor. To test for a causal relationship between the two, the ability of a Na+,K+ ATPase inhibitor to directly influence the level of AHR was determined in a second experiment. Eight allergic and 10 control subjects were administered AHR tests on 2 different days, immediately after inhalation of either nebulized ouabain (1 mg) or placebo in a double-blind fashion. Ouabain versus placebo inhalation decreased the PC20 in four of the patients with allergy. Additionally, ouabain increased methacholine AHR in patients with allergy, as manifested by a lower AUC in seven of the eight patients. In contrast, the mean AUC for the ouabain versus placebo prechallenges did not change significantly in the control group. Finally, a positive correlation was demonstrated between the levels of platelet membrane Na+,K+ ATPase inhibition and bronchial responsiveness to ouabain (r = 0.49, p < 0.05). These results provide both correlative and mechanistic evidence for a causal relationship between Na+,K+ ATPase enzyme inhibition and AHR.
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PMID:The relationship between airway hyperreactivity (AHR) and sodium, potassium adenosine triphosphatase (Na+,K+ ATPase) enzyme inhibition. 905 93