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At least 721 records · Page 40Linked to original sources
PubMed1987

Effect of treatment with hydrochlorothiazide on the red cell Na,K-adenosine triphosphatase in men with hypertension.

We studied the effect of hydrochlorothiazide, 50 mg daily, on Na,K-adenosine triphosphatase (ATPase) activity in the red cells of 10 black men with hypertension. We also examined net sodium and potassium movement in sodium-loaded, potassium-depleted, red cells. Treatment with hydrochlorothiazide resulted in a significant increase in mean ouabain-sensitive ATPase activity (+/- SEM) from 118.4 +/- 14.6 to 158.1 +/- 15.3 nmol phosphate released per milligram of protein (P = 0.0004). Ouabain-resistant ATPase did not change. Net sodium extrusion rose significantly, from 1.62 +/- 0.27 to 2.32 +/- 0.33 mmol/L/hr (P = 0.0275). We postulate that the enhanced activity of the Na,K pump results from the volume contraction induced by the diuretic. This interpretation is consistent with the concept that the Na,K pump is inhibited in volume expansion and volume-expanded hypertension. The finding of enhanced pump activity in subjects given treatment with hydrochlorothiazide suggests a possible mechanism of the antihypertensive action of diuretic therapy.

Adult↗
PubMed2002

Copper-transporting P-type adenosine triphosphatase (ATP7B) as a cisplatin based chemoresistance marker in ovarian carcinoma: comparative analysis with expression of MDR1, MRP1, MRP2, LRP and BCRP.

Intrinsic or acquired resistance to chemotherapy is the major obstacle to overcome in the treatment of patients with solid carcinoma. Cisplatin is one of the most effective chemotherapeutic agents for treating ovarian carcinoma. Recently, copper-transporting P-type adenosine triphosphatase (ATP7B) has been demonstrated as one of the genes responsible for cisplatin resistance in vitro. We hypothesized that the expression of ATP7B gene increases resistance to cisplatin in ovarian carcinoma and a priori knowledge of its expression is important for the choice of therapy. The aim of our study was to assess the role of ATP7B gene in ovarian carcinoma and compare its expression with those of multidrug resistance-related transporters such as MDR1, MRP1, MRP2, LRP and BCRP genes. The transporters' gene expression profiles from 82 patients treated with cisplatin-based chemotherapy after surgery were assessed by RT-PCR. We did not observe any significant correlation between ATP7B gene expression and those of MDR1, MRP1, MRP2, LRP or BCRP. The expression level of ATP7B gene was significantly increased (p < 0.05) in patients with moderately-/poorly-differentiated ovarian carcinomas treated with cisplatin-based chemotherapy, thus ATP7B may serve as an independent prognostic factor in these patients. In contrast, the expression level of MDR1, MRP1, MRP2, LRP and BCRP genes were not prognostic indicators of disease. These findings suggest that ATP7B gene may be considered as a novel chemoresistance marker and that inhibitor(s) of ATP7B might be useful, in patients with ovarian carcinoma treated with cisplatin-based chemotherapy.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed2000

Arsenite-resistant Leishmania donovani promastigotes express an enhanced membrane P-type adenosine triphosphatase activity that is sensitive to verapamil treatment.

An arsenite-resistant strain of Leishmania donovani was generated in vitro by sequential exposure to higher concentrations of sodium m-arsenite. The resistant strain displayed a low level of cross-resistance to structurally unrelated drugs such as doxorubicin and pentamidine. This cross-resistance was sensitive to the calcium-channel blocker verapamil. The membrane-associated P-type adenosine triphosphatase (ATPase) activity detected in crude membrane fractions of the resistant strain was 3-fold that found in the wild-type parasites. The enhanced ATPase activity was unaffected by the presence of verapamil in the reaction mixture. However, when cells were grown in the presence of verapamil the membrane-associated ATPase activity of the resistant strain showed significant inhibition.

Adenosine Triphosphatases↗
PubMed1980

Cytophotometry of post mortem glycogenolysis in quiescent bovine muscle fibres in relation to temperature, succinate dehydrogenase activity and adenosine triphosphatase activity.

Immediate post mortem samples of sternomandibularis muscles from six steers were maintained with a minimum of intrinsic activity at approximately 40 degrees C or allowed to cool to approximately 22 degrees C. Samples were frozen in liquid nitrogen at 0, 2, 4 and 6 h post mortem and serial transverse sections were stained by the periodic acid-Schiff (PAS) reaction for glycogen or reacted for adenosine triphosphatase (ATPase) or succinate dehydrogenase. Individual fibres were mapped and categorized from their ATPase and succinate dehydrogenase activity using a projecting microscope. The absorbance of PAS-stained glycogen in individual fibres was measured with a microscope photometer at 570 and 601 nm with a correction for distributional error. Overall, the post mortem decline in absorbance was approximately twice as fast in body temperature samples relative to room temperature samples. Transient post mortem increases in absorbance were detected in some situations, particularly in fibres with strong ATPase activity from room temperature samples. In fibres with strong ATPase activity, the rate of decline in absorbance increased progressively post mortem. Fibres with weak ATPase mostly had a lower initial post mortem absorbance and were generally the first to become PAS-negative.

Adenosine Triphosphatases↗
PubMed1994

Rapid fluorometric assay for mitochondrial proton adenosine triphosphatase activity for assessment of viability of liver graft tissue.

We developed an improved determination method of mitochondrial proton adenosine triphosphatase (ATPase) activity in the liver. The activity was measured fluorometrically with a 3,3'-dipropylthiodicarbocyanine iodide (diS-C3(5)), which is excited at 625 nm and emits fluorescence at 670 nm. This dye transmits the electric potential across the inner mitochondrial membrane. The fluorescence intensity of diS-C3(5) with mitochondria (100 microliters, 4-16 mg/ml protein) in a 2 ml potassium buffer (pH 7.4) was regarded as a standard electric potential. After confirming the activity of the mitochondrial electron transport chain by succinic acid (9 mumol), we inhibited the chain by antimycin A (1.25 micrograms). Fluorescence intensity decreased by adenosine 5'-triphosphate (ATP) (2 mumol) and oligomycin (25 micrograms) inhibited this depression. The value of mitochondrial proton ATPase activity was calculated as a percentage of the fluorescence intensity change by ATP per the standard electric potential. The activity of mitochondrial proton ATPase in the normal fresh rat livers was 50.3 +/- 2.2%. Good correlation (r2 = 0.807) between two methods for mitochondrial proton ATPase activity, our newly developed method and a conventional colorimetric method, was obtained in the rat livers with various conditions. This method has advantages that the proton ATPase activity can be measured in intact mitochondria, and all procedures can be completed within 40 min. It is suitable for the determination of mitochondrial viability of liver graft in the hepatic resections and transplantations.

Adenosine Triphosphate↗
PubMed1973

Use of progress curves to investigate product inhibition in enzyme-catalysed reactions. Application to the soluble mitochondrial adenosine triphosphatase.

1. Several methods of analysing progress curves of enzyme-catalysed reactions are discussed briefly in relation to their usefulness in a situation where a reaction product has a K(i) much lower than the K(m) for the substrate 2. A comparison is made of different methods of estimating initial rates in this situation. 3. The use of a computer curve-fitting routine capable of handling functions of more than one variable for the extraction of kinetic parameters from progress curves is described. 4. This method and that of fitting time as a polynomial in product concentration are applied to progress curves for the soluble mitochondrial adenosine triphosphatase and the results are compared with values obtained by more conventional methods.

Adenosine Triphosphatases↗
PubMed1994

Hormone-specific defect in insulin regulation of (Ca2+ + Mg2+)-adenosine triphosphatase activity in kidney membranes from streptozocin non-insulin-dependent diabetic rats.

The plasma membrane enzyme (Ca2+ + Mg2+)-adenosine triphosphatase [(Ca2+ + Mg2+)-ATPase] is hormonally regulated, and may participate in Ca2+ signaling by removing excess Ca2+ from the cell. Insulin increases ATPase activity in kidney cortical basolateral membranes (BLM) from normal rats, but fails to do so in membranes from insulin-resistant non-insulin-dependent diabetic (NIDDM) rats. To investigate mechanisms of insulin regulation of ATPase and to evaluate whether the loss of this regulation in diabetes is hormone-specific and depends on blood glucose levels, (Ca2+ + Mg2+)-ATPase function and its hormonal regulation were studied in kidney BLM from rats with mild and severe NIDDM. Km values for ATP and Ca2+ affinity of the ATPase were similar in diabetic and control rats, but the maximal velocity (Vmax) of the enzyme was higher in diabetic groups. Insulin, the protein kinase C (PKC) stimulator 12-0-tetradecanoylphorbol 13-acetate (TPA), parathyroid hormone (PTH), and cyclic adenosine monophosphate (cAMP) all increased the ATPase activity in BLM from controls by increasing the enzyme's affinity for Ca2+. A protein kinase A (PKA) inhibitor (H8 in low concentrations) abolished cAMP and PTH effects, but not those of insulin, whereas the PKC inhibitors (sphingosine and high concentrations of H8) did abolish the effects of insulin. Stimulations of ATPase activity by insulin and by PTH and cAMP were additive. Insulin and TPA lost their stimulatory effects on ATPase in BLM from rats with either mild or severe NIDDM, but PTH and cAMP maintained their stimulatory effects in these membranes. The data show [1] (Ca2+ + Mg2+)-ATPase activity is increased in NIDDM, and a hormone-specific loss of insulin stimulation of ATPase occurs; (2) these defects are not dependent on the level of glycemia; and (3) the stimulatory effects of insulin on the ATPase may be mediated in part via PKC. We suggest that the hormone-specific defect in insulin regulation of ATPase seen in the NIDDM rats may contribute to their insulin resistance.

Animals↗
PubMed1983

A bovine seminal plasma inhibitor of actin-stimulated myosin adenosine triphosphatase.

During attempts to isolate bovine sperm actin, persistent low molecular weight proteinaceous (LMWP) contaminants were found. A LMWP fraction was prepared by gel filtration chromatography on Sephadex G150. The LMWP was found in extracts of washed bovine ejaculated spermatozoa and in clarified bovine seminal plasma. It was substantially reduced in amount in bovine epididymal spermatozoa, indicating that it originated from secondary sex gland secretions. The LMWP inhibited rabbit muscle actin-stimulated myosin adenosine triphosphatase (actin-myosin ATPase) activity. The LMWP:actin ratio for 50% inhibition of actin-myosin ATPase was 2.6 +/- 0.12 mg LMWP per mg actin. The LMWP interfered with actin inhibition of deoxyribonuclease, indicating that LMWP interacted with actin. The LMWP from seminal plasma had an estimated molecular weight of 8300 and consisted of several acidic components. It had negligible protease activity and its inhibition of actin-myosin ATPase was independent of divalent cations. The LMWP appears to readily aggregate with itself and other proteins, which may be related to its physiological role in semen.

Actins↗
PubMed1992

Effects of mebendazole, albendazole, and praziquantel on alkaline phosphatase, acid phosphatase, and adenosine triphosphatase of Echinococcus granulosus cysts harbored in mice.

Mice infected with protoscoleces of Echinococcus granulosus for 12-14 months were treated ig with mebendazole (Meb) 25-50 mg.kg-1 x d-1 for 7-14 d, albendazole (Alb) 200 mg.kg-1 x d-1, cr praziquantel (Pra) 500 mg.kg-1 x d-1 for 14 d. The mice were killed 24 h after the last medication, and acid phosphatase (ACP), alkaline phosphatase (AKP), and adenosine triphosphatase (ATPase) including (Na, K, Mg)-ATPase, (Na, K)-ATPase, and (Mg)-ATPase were determined and compared with those of untreated control group. The results showed that ACP activities of cyst wall in treated groups were lower than the control group. Whereas AKP activity of cyst wall in Pra group increased markedly, this is not the case in Meb and Alb groups. Three ATPase activities of cyst wall were inhibited in both Meb and Alb groups, Meb being more potent. No apparent changes in the ATPase activities were seen in Pra group.

Acid Phosphatase↗
PubMed1975

The significance of inhibitor-resistant alkaline phosphatase in the cytochemical demonstration of transport adenosine triphosphatase.

The hydrolysis of disodium p-nitrophenyl phosphate at pH 9.0 by slices of formaldehydee-fixed rat renal cortex was investigated by colorimetric estimation of the nitrophenol liberated. It was found that three types of activity could be identified on the basis of their responses to inhibitors and cations: (a) alkaline phosphatase sensitive to inhibition by L-tetramisole; (b) potassium-dependent phosphatase, probably identifiable with the phosphatase component of sodium-potassium-dependent transport adenosine triphosphatase (?Na-K-ATPase); and (c) alkaline phosphatase insensitive to L-tetramisole. It was found that in the presence of strontium ions, as used in Na-K-ATPase cytochemistry, the activities of the second and third types of enzyme were approximately equal. The implications of these findings for the cytochemical demonstration of Na-K-ATPase are discussed.

4-Nitrophenylphosphatase↗
PubMed2003

The zonal distributions of alkaline phosphatase, adenosine triphosphatase, laminin, fibronectin and chondroitin 4-sulphate in growing rat humerus proximal epiphyseal cartilage: a histochemical and an immunohistochemical study.

Although there are many studies about epiphyseal cartilage extracellular matrix (ECM) macromolecules in bone formation, studies of their distribution and role in the mineralization of these components in growing rat humerus proximal epiphyseal cartilage have not been sufficiently detailed. The aim of this study was to determine the distributions of alkaline phosphatase (ALP), adenosine triphosphatase (ATPase), laminin, fibronectin and chondroitin 4-sulphate in growing rat humerus proximal epiphyseal cartilage. The rats were killed by cervical dislocation, and the humeri were removed, sectioned (6 and 10 microm) on a cryotome or paraffin microtome, and stained using histochemical and immunohistochemical methods. ALP and ATPase were markedly observed in the hypertrophy and calcifying cartilage. In addition, ATPase was found to be very strongly positive in the tangential zone of articular cartilage. Results of immunohistochemical staining for laminin, fibronectin and chondroitin 4-sulphate showed that the immunostaining was the heaviest in the tangential zone of articular cartilage. In growing epiphyseal plates, there were differences in the density of these macromolecules of chondrocytes as a function of the maturation process. In conclusion, these ECM macromolecules of epiphyseal cartilage may regulate the cell-cell and cell-matrix interactions as well as the matrix calcification during the ossification of epiphyseal cartilage.

Adenosine Triphosphatases↗
PubMed2002

Adenosine triphosphatase expression correlates with ciliary activity of respiratory epithelium in vitro.

In vitro culture of respiratory epithelium is of great utility for pharmacological investigations and tissue engineering. Up to now, the degree of differentiation of respiratory cells cultured in vitro has exclusively been estimated by measuring ciliary beat frequency (CBF). Ciliary motility is dependent on the function of the motor protein dynein that is composed of at least two heavy chains, sharing attributes of adenosine triphosphatases (ATPases). CBF is further dependent on medium conditions and does not allow to draw any accurate conclusion on the proportion of fully differentiated ciliated cells in culture. For this reason we introduced the immunohistochemical detection of a 100-kD ATPase subunit as a correlation with dynein activity in human respiratory cell tissue culture. Our results show that the amount of immunohistochemically detectable ATPase-subunit-positive cells strongly correlates with ciliary motility in vitro. Cultures without ciliary activity exhibited no ATPase staining, whereas in cell cultures with excessive ciliary beat, up to 15.1% of the cells were ATPase positive. Immunohistochemical detection of ATPase in respiratory cell cultures seems to be a sensitive and reproducible complement for the characterization of cultured ciliated epithelium.

Adenosine Triphosphatases↗
PubMed1984

Effects of vitamin D3 deficiency on adenosine triphosphatase activity of jejunums from white Leghorn hens.

Supplemental vitamin D3 (D3) was removed from the diet given to an experimental group of White Leghorn hens, at 227 days of age, while a control group continued to receive a supplemental diet. By 14 days after D3 withdrawal, egg weight, egg specific gravity, shell weight, percent shell, shell thickness, and plasma calcium were lower (P less than .05) in the experimental compared to the control group. At 30 to 37 days after D3 withdrawal, experimental hens had less (P less than .05) jejunal adenosine triphosphatase (ATPase) activity than the control hens. The study indicated that lack of D3 supplementation in laying diets reduced jejunal ATPase activity as well as egg shell quality.

Adenosine Triphosphatases↗
PubMed1977

An oligomycin-resistant adenosine triphosphatase and its effects on cellular growth, mitochondrial oxidative phosphorylation and respiratory proton translocation in Saccharomyces cerevisiae.

Mutations at the OLI 1 or OLI 2 loci of mitochondria DNA in Saccharomyces cerevisiae are associated with a diminished growth rate in nutritionally suboptimal cultures supplemented with an oxidizable carbon source. In the case of mutant OR146(OLI1) there is a 35% loss of mitochondrial protein during fractionation in vitro, suggesting that the mutationally altered adenosine triphosphatase(ATPase) confers some instability on the mitochondrial membrane. The possibility is discussed that this reflects an unstable mitchondrial population in vivo, leading the observed growth deficiency. Mitochondria from mutant OR146 at the OLI 1 locus show a relatively oligomycin-resistant State-3 respiration, but the same ADP/O and respiratory-control quotients as the isonuclear wild-type. A slightly lowered Qo2 with NADH-linked substrates was observed and is discussed. For both strains the apparent H+/O ratios were close to 4 with pyruvate, ethanol and alpha-oxoglutarate, but consistently lower with succinate and citrate. For each substrate a characteristic t 1/2 (time for half-decay of the transmembrane pH differential) range was found, consistent with the view that the substrates effecitvely carry the protons back across the membrane. As expected, H+/O ratios were independent of t 1/2 for all substrates, with the exception of alpha-oxoglutarate in the case of the wild-type, where an inverse correlation was found. The lack of this correlation in the case of the mutant was the only apparent difference in the translocation parameters observed. A hypothesis relating this to the functioning of the oligomycin-resistant ATPase is proposed.

Adenosine Triphosphatases↗