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)

Ouabain-sensitive uptake of 86Rb+ (an analogue of K+) was enhanced in L-cells that had been treated with 25-hydroxycholesterol or 7-ketocholesterol in order to deplete their sterol concentration. Ouabain-insensitive Rb+ efflux also increased in the sterol-depleted cells and the intracellular concentration of K+ diminished while the concentration of Na+ increased. All of these effects of 25-hydroxycholesterol were counteracted by the addition of mevalonate to the culture medium. Despite the evidence for increased active Rb+ transport in the 25-hydroxycholesterol-treated cells, the level of sodium and potassium ion-activated adenosine triphosphatase ((Na+ + K+)-activated ATPase) activity measured in homogenates and plasma membrane preparations from the treated cells was not significantly different from the control values. Rb+ uptake was more sensitive to ouabain inhibition in sterol-depleted cells than in control cells, although ATPase activity in plasma membrane fractions isolated from treated cells was not more sensitive to ouabain inhibition than was that from control cells. It is possible that the ability of the oxygenated sterols to inhibit DNA synthesis and cell division (Kandutsch, A. A., and Chen, H. W. (1977) J. Biol. Chem. 252, 409-415) is related to their effects upon cellular ion transport.
 ...
PMID:Alteration of 86Rb+ influx and efflux following depletion of membrane sterol in L-cells. 64 Oct 62

Principally to ascertain whether mineral metabolism is involved in weight regulation, the 40 most obese of 1,774 children, aged 10-11 years, screened for obesity were compared with 46 age-matched controls. The obese children had more 3H-Ouabain erythrocyte binding sites (p = 0.04), higher intracellular sodium (p = 0.04), and lower plasma sodium (p = 0.002). After exclusion of the non-Scandinavians, the p values were p = 0.02, p = 0.03, and p = 0.03, respectively. Analysis of variance also showed the differences to be more dependent on obesity than on gender or nationality. It is concluded that obese children have more 3H-Ouabain erythrocyte binding sites indicating an increase of the sodium-potassium adenosine triphosphatase activity. The increase of intracellular sodium may increase the risk of future hypertension.
 ...
PMID:Red cell sodium-potassium adenosine triphosphatase sites and intracellular sodium increased in obese school children. 132 34

We studied the effect of extracellular sodium concentration on histamine release (HR) from human basophils initiated by immunologic and nonimmunologic stimuli. We found that lowering extracellular sodium markedly enhances HR induced by an immunologic stimulus from these cells. In buffer in which sodium had been replaced with univalent ions of strong bases, enhancement of HR increased as extracellular sodium decreased. Enhancement was the result of increased duration of release. When sucrose was used for replacement of sodium, we also observed that enhancement of HR increased as extracellular sodium decreased, but there was some lessening of enhancement at [Na+]e between 5 and 10 mmol/L. Ouabain, which is an inhibitor of the Na+/K+ adenosine triphosphatase, and bumetanide and furosemide, which are inhibitors of Cl(-)-dependent Na(+)-K+ cotransport, caused small increases in enhancement of HR by sodium-deficient buffers; 4,4'-diisothiocyanostilbene-2-2'-disulfonic acid, an anion transport inhibitor, caused some inhibition of enhancement of HR. Analogues of amiloride, such as 5-(N-N-hexamethylene) amiloride (HMA) and 5-(N-4-chlorobenzyl)-2'-4'dimethylbenzamil (CBDMB), inhibit Na+/H+ exchange, Na+/Ca++ exchange, and Na+ channels. Interestingly, at higher doses, HMA and CBDMB caused marked enhancement of HR in both normal and sodium-deficient buffers. These results suggest that several cellular regulatory mechanisms potentially are important for normal basophil secretion. The most likely are pH regulatory mechanisms that include Na+/H+ exchange and anion exchangers that transport alkaline equivalents. Our findings enhancement of basophil HR by HMA and CBDMB is particularly noteworthy in light of the recent interest in use of amiloride by inhalation for therapy of lung disease in patients with cystic fibrosis.
 ...
PMID:Role of sodium in mediator release from human basophils. 137 73

The density of Na/K adenosine triphosphatase (ATPase) pumps in retinal pigment epithelial (RPE) cells in different retinal regions was quantified by measuring the binding of 3H-ouabain to RPE in cow and human eyecups. In bovine eyes, pump density was estimated in RPE samples isolated from three retinal regions outlined with a 7-mm trephine: one from the posterior pole in the area centralis and two from the superior, equatorial retina representing unpigmented (in the tapetum) and pigmented zones. In human eyes, RPE samples were isolated from a posterior region centered around the macula and one superior region. Ouabain binding to RPE of the posterior pole of both species was approximately 40-60% lower than binding to RPE of more peripheral regions in the same eyes. For bovine eyes, ouabain binding did not differ between pigmented and unpigmented cells of the superior retina, suggesting that reduced binding in the relatively amelanotic posterior cells was not related to levels of pigmentation. For human RPE, binding to posterior cells was lower in eyes from donors of all ages (range, 17-90 yr). The data suggest that Na/K ATPase pump site density is lower in posterior RPE cells of both bovine and human eyes, perhaps due to a regional difference in requirements for ionic regulation.
 ...
PMID:Retinal pigment epithelial cells of the posterior pole have fewer Na/K adenosine triphosphatase pumps than peripheral cells. 164 75

Ciliary epithelium was isolated from the rabbit eye and used as a source of plasma membrane material for sodium, potassium-adenosine triphosphatase (Na,K-ATPase) measurements. In the presence of 12(R)-hydroxyeicosatetraenoic acid [12(R)HETE], Na,K-ATPase (ouabain-sensitive ATPase) activity was reduced from 22.5 to 16.3 microM phosphate released/mg protein/hr. Ouabain-insensitive ATPase activity was not altered by 12(R)HETE. No changes in ciliary epithelium ATPase activity were observed in the presence of 12(S)HETE. In parallel studies with conscious rabbits, 12(R)HETE applied topically to the eye was found to lower intraocular pressure (IOP). It is possible that the IOP-lowering effect of 12(R)HETE may be, in part, associated with its ability to suppress the Na,K-ATPase activity of the ciliary epithelium.
 ...
PMID:The influence of 12(R)-hydroxyeicosatetraenoic acid on ciliary epithelial sodium, potassium-adenosine triphosphatase activity and intraocular pressure in the rabbit. 165 Dec 97

Plasma membrane-associated adenosine triphosphatase (ATPase) samples partially purified from the tumor dissections of 15 gastric cancer patients were examined for sensitivity to the synthetic lignan, 2,3-dibenzylbutane-1,4-diol (hattalin), and ouabain in the presence of Mg2+, Na+, and K+. Hattalin was the strongest Na+, K(+)-ATPase inhibitor among the lignans previously examined. The enzyme from normal gastric tissue of the same patient was used as control. The specific activity of ATPase from cancer tissue (C-ATPase) was inhibited by more than 50% by 2.0 mM hattalin, whereas only 33.1% of the specific activity of ATPase from normal gastric mucosa (N-ATPase) was inhibited by 2.0 mM hattalin. There was statistical significance of lignan sensitivity between C- and N-ATPase (p less than 0.02). Ouabain also inhibited C-ATPase in preference to N-ATPase, though not significantly. Hattalin inhibited both C- and N-ATPase more strongly than did ouabain (p less than 0.05). Moreover, the lignan inhibited both C- and N-ATPase in the absence of Na+ and K+. From these data, it is evident that the sensitivity of plasma membrane-associated to lignan increased by gastric canceration. The target ATPase of hattalin is likely to be one other than sodium- and potassium-dependent, ouabain-sensitive ATPase.
 ...
PMID:Differential sensitivity of human gastric cancer ATPase and normal gastric mucosa ATPase to the synthetic mammalian lignan analogue 2,3-dibenzylbutane-1,4-diol (hattalin). 183 Aug 24

Prostacyclin (PGI2) did not alter the basal perfusion pressure in the isolated rat mesenteric arteries perfused with Krebs' solution, but produced a biphasic effect in arteries preconstricted with norepinephrine or arginine vasopressin: constriction, then prolonged dilation. Both these components of PGI2 effect were diminished in arteries denuded of their endothelia by a 10 min perfusion with distilled water or p-bromophenacyl bromide (10 microM). The present study elucidates the mechanism of these PGI2 actions. Indomethacin (0.28 microM) SQ 29548 (1 microM, thromboxane A2 receptor antagonist), saralasin (1 microM, angiotensin II receptor antagonist) or the free radical scavengers, superoxide dismutase (60 U/ml) and catalase (40 U/ml) did not inhibit the initial vasoconstriction, suggesting it was not mediated through endothelially generated thromboxane A2, angiotensin II or oxygen-derived free radicals. However, ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid (50 microM; Ca++ chelating agent), 8-(diethyl-amino)octyl 3,4,5-trimethoxy benzoate (10 microM; intracellular Ca++ antagonist), or neomycin (5 mM; phospholipase-C inhibitor) abolished the vasoconstriction. Ouabain (0.5 mM) did not affect the vasodilation, but perfusion with excess (50 mM) or 0 K+ Krebs' solution abolished it, suggesting this PGI2 action involves changes in membrane K+ conductance via a mechanism independent of Na+/K+ adenosine triphosphatase. Vasodilation evoked by BRL 34915 (K+ channel activator) was similarly attenuated under these conditions, but not by ouabain. Furthermore, procaine (1 mM; nonspecific K+ channel inhibitor), but not apamin (0.5 microM) or tetraethylammonium (10 mM) blocked PGI2- and BRL 34915-induced vasodilation.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Mechanism of vascular actions of prostacyclin in the rat isolated perfused mesenteric arteries. 210 93

The effect of ouabain on the uptake of tritiated [3H]GABA and on its release in the absence of Ca(+)+ was studied in brain cortex synaptosomes. Ouabain, in the absence of Ca(+)+ and K(+)-depolarization, induces the release of [3H]GABA with half-maximal effect occurring at a concentration of about 7 X 10(-6) M. Parallel measurements of the effects of ouabain on the [3H]GABA uptake and the Na+,K(+)-adenosine triphosphatase activity show that ouabain inhibits both mechanisms and that the half-maximal effect also occurs at about the same ouabain concentration. Although [3H]GABA release is stimulated by ouabain, it appears that the inhibition of [3H]GABA uptake is due to a direct effect on the uptake mechanism, inasmuch as the initial velocity of the process is inhibited by ouabain. Ouabain requires extracellular Na+ for [3H]GABA release and for membrane depolarization and, in the absence of Na+, ouabain does not cause either [3H]GABA release or membrane depolarization. No significant changes in the Na+ gradients occur under conditions which permit release of [3H]GABA, but the Na+,K(+)-adenosine triphosphatase activity is inhibited, which may be responsible for membrane depolarization, which in turn may cause [3H]GABA release or inhibit its uptake.
 ...
PMID:Effect of ouabain on the gamma-[3H]aminobutyric acid uptake and release in the absence of Ca(+)+ and K(+)-depolarization. 216 3

1. To determine whether alterations in membrane sodium transport in airway smooth muscle can alter its contractility, we studied the effect of ouabain (a Na+/K(+)-adenosine triphosphatase inhibitor) and amiloride on contractile responses in bovine trachea and human bronchial rings in a series of studies. 2. Ouabain (10(-6)-10(-4) mol/l) caused concentration-related contraction of bovine trachea with a maximum effect at 30 min; the mean increases in tension with 10(-6), 10(-5) and 10(-4) mol/l ouabain were 19, 27, and 32%, respectively, of the maximum response seen with 10(-3) mol/l histamine (n = 6). In human bronchial rings, ouabain (10(-5) mol/l) caused a mean contraction which was 40% of the maximum response to methacholine (n = 8). 3. Calcium-free fluid (plus ethylenediaminetetraacetic acid) and nifedipine (10(-5) mol/l) inhibited ouabain-induced contractions, suggesting that contraction was mediated in part by calcium entry via voltage-dependent calcium channels. Phentolamine (10(-5) mol/l) was without effect. 4. Ouabain (10(-5) mol/l) did not alter histamine responsiveness in bovine trachea or methacholine responsiveness in human bronchial rings. 5. Amiloride did not affect resting tone in bovine trachea but caused a concentration-dependent relaxation of bovine tracheal strips preconstricted with carbachol, 10(-3) mol/l amiloride relaxing strips completely over 15 minutes (n = 8).(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Effect of sodium-transport inhibitors on airway smooth muscle contractility in vitro. 217 51

Spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were used to investigate the adaptive biochemical changes in the myocardium in response to chronic afterload. Ouabain-inhibited Na+,K+-adenosine triphosphatase (ATPase) activity was decreased by 40% in myocardium of SHR compared with that from WKY, which may lead to increased intracellular Ca2+ through Na+-Ca2+ exchange. Similarly, alpha 1-adrenergic receptor density, estimated by [3H]prazosin binding, was decreased by 42% in myocardial membranes of SHR, while the affinity for the agonist and the antagonist was not altered. In contrast, the number of Ca2+ channels estimated by [3H]nitrendipine binding was increased by 45% in myocardial membranes of SHR, while the affinity was comparable between SHR and WKY. These differences between WKY and SHR in the membrane properties were not due to differential contamination of plasma membranes because the activities of other putative plasma membrane marker enzymes were comparable between WKY and SHR. There were no differences between WKY and SHR in the myosin ATPase activity estimated using myofibrils, actomyosin, and myosin. These results suggest that specific alterations have occurred in the plasma membrane properties of myocardium of SHR that result in altered intracellular Ca2+ metabolism. These alterations may have an important bearing on excitation-contraction coupling in myocardium of SHR.
 ...
PMID:Alterations in the plasma membrane properties of the myocardium of spontaneously hypertensive rats. 242 36


<< Previous 1 2 3 4 5 6 7 8 9 Next >>