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)

Phenytoin stimulated renin secretion from rat renal cortical slices. A sigmoid relationship was found between stimulatory effect and log concentration, from 1 to 8 mg/100 ml. The ED5C was 2.8 mg/100 ml. Basal secretion and the stimulation of secretion elicited by phenytoin were blocked by incubating slices in a K-free medium and by adding 1 mM ouabain to the medium (both of which inhibit Na,K-adenosine triphosphatase activity and increase intracellular Na concentration), and by reductions in the Na concentration of the incubation medium. NaCl in the incubation medium was replaced by choline chloride so that osmolality and Cl concentration were held constant. It is suggested that renin secretion rate is directly related to the transmembrane Na gradient, that phenytoin stimulates secretion by increasing the gradient, and that ouabain, K-free medium and reductions in Na concentration of the medium inhibit secretion by reducing the gradient.
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PMID:Phenytoin stimulates renin secretion from rat kidney slices. 51 21

In vascular smooth muscle, oxidative phosphorylation and glycolysis are independently regulated. Previous studies indicated that the independent regulation of these pathways was related to a compartmentation of carbohydrate metabolism. To further study carbohydrate metabolism, glucose transport and the incorporation of radiolabel from glucose into glycogen and lactate were measured after the oxidative and glycolytic pathways were independently altered. Ouabain stimulated mechanical activity, oxygen consumption, and glycogenolysis, whereas lactate production was decreased. Although glycogenolysis was substantial, glucose was the only substrate for lactate, indicating that intermediates derived from glycogen do not mix with those from glucose uptake. Thus glycogenolysis and glycolysis are carried out by independent enzymatic pathways. Insulin-stimulated lactate production and glucose transport without affecting the other parameters. Again, lactate was produced only from glucose. Phenytoin decreased isometric tension and oxygen consumption, whereas stimulating lactate production and glycogenolysis. Glycogen was the primary substrate for the lactate produced. Our findings indicate that the compartmentation of substrate utilization is ascribable to the coordination of glycogenolysis with increases in oxygen consumption and the coupling of glycolysis to the Na-K-adenosine triphosphatase. The coupling of independent energy providing pathways to specific endergonic processes indicates a mechanism by which cellular energetic efficiency may be optimized.
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PMID:Compartmentation of carbohydrate metabolism in vascular smooth muscle. 303 Jan 31

To investigate the molecular mechanisms of the inhibition of Na+,K(+)-adenosine triphosphatase (Na+,K(+)-ATPase) in diabetes mellitus, we incubated Na+,K(+)-ATPase purified from human placenta of six healthy nondiabetic women with plasma from six insulin-dependent diabetic (IDDM) men and six healthy controls and with different concentrations of lysophosphatidylcholine (LPC). We determined the enzyme activity, anthroyl ouabain-binding capacity, dissociation constant (Kd), and average lifetime values (tau) by the static and dynamic fluorescence of anthroyl ouabain. The lipid annulus of the enzyme was studied by static and dynamic fluorescence of 1-(4-trimethylamino-phenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH). Moreover, we studied the lipid microenvironment surrounding the Na+,K(+)-ATPase purified from the placentas of six healthy women and six insulin-dependent diabetic women, determining the percent composition of phospholipids of the lipid annulus. The addition of total and protein-free IDDM plasma to normal Na+,K(+)-ATPase significantly inhibited the enzymatic activity even at the lowest concentration studied (1: 100), whereas the ouabain-binding capacity, Kd, and tau were not affected by IDDM plasma. The fluorescence polarization and lifetime values of TMA-DPH were significantly decreased by diabetic plasma. The incubation of Na+,K(+)-ATPase with LPC caused an inhibition of the enzymatic activity without modifications of the anthroyl ouabain-binding capacity and dissociation constant. The fluorescence polarization and lifetime values of TMA-DPH were significantly decreased by 5 mumol/L LPC. The study of the phospholipids surrounding Na+,K(+)-ATPase demonstrated a significant increase in the percent LPC content in IDDM patients compared with controls together with a concomitant decrease in phosphatidylcholine. These observations indicate that the inhibition caused by diabetic plasma on Na+,K(+)-ATPase is not dependent on a modification of the ouabain-binding site and that it seems to mimic the effect of LPC addition. A link between modification of the lipid moiety of the enzyme and Na+,K(+)-ATPase inhibition might be hypothesized.
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PMID:Modifications induced by plasma from insulin-dependent diabetic patients and by lysophosphatidylcholine on human Na+,K(+)-adenosine triphosphatase. 966 19

The aim of the present study was to evaluate the action of plasma from insulin-dependent diabetic (IDDM) pregnant women on nitric oxide synthase (NOS) activity in cultured human umbilical vein endothelial cells (HUVECs). We also studied the effect of the plasma on cytosolic calcium and on Na+/K+-adenosine triphosphatase (ATPase) activity. Dynamic fluorescence studies of membrane fluidity were contemporarily performed to detect a direct effect of plasma on the endothelial cell membrane. We observed a significant increase in NOS activity, intracellular calcium, and Na+/K+-ATPase activity in cultured HUVECs exposed to IDDM plasma. Our dynamic fluorescence study showed a different microenvironmental organization of the cellular membrane after incubation with plasma from IDDM pregnant women, with a marked decrease in microheterogeneity as evaluated in terms of 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) lifetime distribution width. The present investigation suggests that plasma from IDDM pregnant women can cause a generalized disturbance in the function of endothelial cells cultured from healthy subjects. Such a modification might play a central role in the pathogenesis of the vascular complications of the disease.
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PMID:A study on human umbilical cord endothelial cells: functional modifications induced by plasma from insulin-dependent diabetes mellitus patients. 1033 52

Sialic acid (SA) content, membrane fluidity, and Na(+)/K(+)-adenosine triphosphatase (ATPase) activity were determined in erythrocyte membrane from 10 nonpregnant women (HNPW), 16 pregnant women affected by gestational diabetes mellitus (GDM), and 25 healthy pregnant women (HPW). In GDM patients the membrane erythrocyte SA content was significantly increased compared with HNPW and membrane fluidity was significantly increased in comparison with HPW. Erythrocyte membrane Na(+)/K(+)-ATPase activity was significantly reduced in GDM patients compared both to HNPW and to HPW subjects. A significant inverse correlation was found between 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) anisotropy and erythrocyte membrane SA content in HNPW and in HPW, while this significant correlation was not observed in GDM. The present results indicate that in comparison with normal pregnancy GDM is characterized by deep alterations of the erythrocyte plasma membrane physicochemical properties (increased fluidity) and functional activities (reduced Na(+)/K(+)-ATPase activity). These modifications might be at the basis of the altered blood viscosity and placental perfusion observed under such conditions. Moreover, these results show that in physiological pregnancy and in the nonpregnant state, the erythrocyte surface membrane fluidity is inversely correlated with SA content, while in GDM there is an unbalance of this relation, which might be associated with the microcirculatory abnormality present in this disease.
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PMID:Sialic acid content in erythrocyte membranes from pregnant women affected by gestational diabetes. 1197 93

The aim was to investigate low-density lipoprotein (LDL) composition and Na(+)/K(+) adenosine triphosphatase (ATPase) and Ca(2+) ATPase activities and membrane fluidity measured by 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) in platelets from obese patients and controls in order to identify, if any, platelet membrane's chemical-physical and/or functional modifications associated with compositional modification of circulating lipoproteins. Moreover, we studied the in vitro effect on both platelet transmembrane cationic transport and fluidity, by incubating LDL from 30 obese subjects with platelets from 30 control subjects. The analysis of the chemical composition of LDL from obese patients showed a significant increase in the percent content of total cholesterol (TC) and triglycerides (TGs) and in the mean levels of lipid hydroperoxides compared to controls' LDL. Platelet Na(+)/K(+) ATPase and Ca(2+) ATPase activities showed, respectively, a significant decrease and increase in patients compared to controls; minor significant, respectively, decreases and increases are shown also in control platelets incubated with LDL from obese patients. Anisotropy tested with TMA-DPH probe was significantly increased both in platelets from obese patients and in control platelets incubated with LDL from obese patients compared to control platelets. This study highlights that obesity induces remarkable modifications both in lipoproteins and platelets. Both platelet hyperfunction and quantitative/qualitative alterations in plasma lipoproteins, as well as an altered interaction between circulating lipoproteins and platelets, might play a relevant role in the increased prevalence of the early atherosclerotic lesions development in obese subjects. The present data point out that obesity might represent a major potentially modifiable risk factor for the onset of numerous complications, in particular cardiovascular ones.
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PMID:Interactions between lipoproteins and platelet membranes in obesity. 1919 63