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PubMed1993

In vivo and in vitro studies on the effect of larvin and cypermethrin on adenosine triphosphatase activity of male rats.

Liver is removed from albino rat and assayed for total adenosine triphosphatase (ATPase) activity following administration with single and repeated doses of larvin and cypermethrin. The data indicate that the total (Na+, K+; Mg2+) dependent ATPase in the liver tissue is significantly inhibited by single and repeated doses of both insecticides. This inhibition is more pronounced by the repeated dose of cypermethrin than that of larvin. The in vitro study revealed that the inhibition encountered by different concentration of both larvin and cypermethrin is of the irreversible non-competitive type. This data indicate that these insecticides can cause biochemical and histopathological changes in the liver ATPase activity which may inhibit several biochemical functions of ATPase system such as: the active transport of metal ions, oxidative phosphorylation of liver cells and generally the muscle contraction.

Adenosine Triphosphatases↗
PubMed2000

Ivermectin: concentration-dependent effects on adenosine triphosphatases in adult worms of Onchocerca volvulus.

The effect of increasing concentrations of ivermectin on adenosine triphosphatase (ATPase) activity was investigated in adult worms of Onchocerca volvulus. Mean Mg- and Na,K-ATPase activities decreased significantly (F ratio = 29.82, P < 0.01 and F ratio = 28.54, P < 0.01, respectively) with increasing concentrations of ivermectin (0-100 ng/ml) in the female worms. When male and female worms were mixed with equal amounts of proteins from each, only the Na,K-ATPase activity was significantly decreased (F ratio = 56.61, P < 0.01) over a similar range of ivermectin concentrations. Since ivermectin exhibits concentration-dependent effects on both ATPases in female adult worms, this might provide an insight into other effects of the drug. However, the adjustment of the dose of ivermectin to obtain a nodular concentration of at least 40 ng/ml is therefore recommended in the complete chemotherapy of onchocerciasis.

Adenosine Triphosphatases↗
PubMed1971

The distribution of sodium-potassium--activated adenosine triphosphatase in medulla and cortex of the kidney.

The activity of sodium-potassium-activated adenosine triphosphatase (Na-K-ATPase) is considerably higher in homogenates of outer medulla than in the cortex or papilla of the kidney. The enzyme has similar kinetic characteristics in both cortex and medulla, and binds ouabain in the same proportion. The discrepancy in enzymatic activity is not paralleled by similar change in the activity of adenyl cyclase, 5'nucleotidase, glucose-6-phosphatase, or succinic dehydrogenase. Na-K-ATPase is also higher in distal convoluted tubules (ventral slices) than in the proximal tubules (dorsal slices) of the kidney of Amphiuma. The high concentration of Na-K-ATPase in the red medulla of the kidney is probably related to the presence here of the thick ascending limb of the loop of Henle, and this has important implications with regard to the mechanism of sodium reabsorption by different portions of the nephron.

Absorption↗
PubMed1981

Mg2+-activated adenosine triphosphatase from Crithidia fasciculata: purification and inhibition by suramin and efrapeptin.

The mitochondrial Mg2+-activated adenosine triphosphatase (ATPase; EC 3.6.1.4) from the insect flagellate Crithidia fasciculata ATCC 11745 has been extracted from the membrane by chloroform treatment and purified to electrophoretic homogeneity by a method involving ammonium sulphate fractionation, gel filtration on Sephadex G-200 and DEAE-cellulose chromatography. The molecular weight of the native enzyme, determined by gel filtration, was about 350 000. Five subunits were detected by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate, with molecular weights of 54 000, 45 000, 35 000, 20 000 and 10 000. The membrane-bound, but not the soluble (F1) ATPase was inhibited by oligomycin and leucinostatin. Both forms of the enzyme were strongly inhibited by the antibiotic efrapeptin and the trypanocidal drug suramin. The inhibition by efrapeptin was of the mixed type, with double-reciprocal plots intersecting below the abscissa, as in the case of the enzyme present in beef heart submitochondrial particles. Suramin, on the other hand, acted as a non-competitive inhibitor of the membrane-bound ATPase and as a strictly competitive inhibitor of the purified F1 ATPase.

Adenosine Triphosphatases↗
PubMed1975

Oxygen exchange in the gamma-phosphoryl group of protein-bound ATP during Mg2+-dependent adenosine triphosphatase activity of myosin.

When ATP binds to myosin in the presence of Mg2+ there follows a rapid cleavage reaction to yield a myosin-product complex whose breakdown is rate-limiting in the overall adenosine triphosphatase reaction at 21 degrees and pH 8.0. Recent kinetic studies on this system have led to the proposal that the cleavage of ATP bound to myosin is reversible. This conclusion is based in part on the observation that when ATP is mixed with an excess of myosin active sites a small amount of tightly bound ATP exists whose life-time coincides with that of the myosin-product complex and implies these two species are in equilibrium during their decay. Previous oxygen exchange studies have shown that phosphate released as free product contains more than one oxygen atom from water. A rapid equilibration between myosin-bound ATP and a myosin-products complex can account for the extra water oxygen incorporation of the product phosphate. Such a model requires that the gamma-phosphoryl group of the bound ATP also exchanges its oxygen atoms with water. Results presented in this paper show that protein-bound ATP labeled in the three terminal oxygen atoms of the gamma-phosphoryl group with 18O exchanges about 75% of its label within 2 s of binding to the active site of myosin. This result provides chemical evidence for a model in which bound ATP undergoes a reversible reaction with water. Incomplete exchange may arise from kinetic and/or structural restraints on the mechanism and plausible models are discussed.

Adenosine Triphosphatases↗
PubMed1981

[(Na+, K+)-dependent adenosine triphosphatase in the rat brain, heart and kidney. Changes in the enzymatic metabolic quotient in purification with sodium deoxycholate].

The usage of detergents is included in most of the proposed methods for purification of a membrane bound enzyme (Na+, K+)-dependent adenosine triphosphatase (EK 3.6.1.3). The detergents influence the lipid envelope of an enzyme, which is considered as an integral part of the enzymic molecule, and extract nonactive proteins from the membrane. The aim of the work is measurement of the metabolic number of the enzyme after two-fold treatment with ionic detergent-sodium desoxycholate in brain, renal and heart tissue of a rat. He finds that the desoxycholate alters the metabolic number in the preparations from renal and brain tissue and does not change it in the heart tissue. These differences according to the author are due to differences in the membrane structures of the tissues. The usage of two-fold treatment of enzyme preparations with sodium desoxycholate is unsuitable for purification of (Na+, K+)-dependent adenosine triphosphatase in kidneys and brain.

Animals↗
PubMed1985

A high-performance liquid chromatographic method for the assay of Na+, K+-adenosine triphosphatase inhibition.

A new method for the assay of Na+, K+-adenosine triphosphatase (Na+, K+-ATPase) inhibition has been devised involving the determination of enzymatically produced adenosine diphosphate (ADP) and unchanged adenosine triphosphate (ATP) by high-performance liquid chromatography (HPLC). The substrate, ATP, was incubated with the enzyme preparation in the presence of an inhibitor. The incubation mixture was filtered through a membrane filter, and ADP and ATP in the filtrate were separated by (HPLC). The inhibitory effect of a cardiac steroid on the enzymic reaction was estimated by measuring the peak area ratio of ADP to ADP plus ATP on the chromatogram. The proposed assay method has proved to be satisfactory with respects to simplicity, sensitivity, and reproducibility.

Adenosine Diphosphate↗
PubMed1971

Properties of the sarcolemmal calcium ion-stimulated adenosine triphosphatase of hamster skeletal muscle.

1. A sarcolemmal fraction was isolated from hamster hind-leg skeletal muscles by successive treatment with lithium bromide and potassium chloride. The membranous fraction was observed to contain a highly active Ca(2+)-stimulated ATPase (adenosine triphosphatase), a Mg(2+)-stimulated ATPase, and an Na(+)+K(+)-stimulated Mg(2+)-dependent ouabain-sensitive ATPase. 2. The Ca(2+)-stimulated ATPase activity was pH-dependent, the optimum being pH7.6. 3. Optimum activation of this enzyme was obtained with 3-4mm-Ca(2+) when 4mm-ATP was present as a substrate, and was not influenced by Na(+), K(+) or ouabain, whereas 2,4-dinitrophenol, sodium azide, oligomycin, sodium fluoride and ethanedioxybis(ethylamine)tetra-acetate were inhibitory. 4. The Ca(2+)-stimulated ATPase was markedly inhibited by thiol-blocking reagents, and cysteine was able to reverse this inhibition. 5. Various bivalent cations stimulated ATP hydrolysis by the sarcolemmal fraction in the following decreasing order of potency: Mg(2+), Ca(2+), Mn(2+), Co(2+), Sr(2+), Ba(2+), Zn(2+), Cu(2+).

Adenosine Triphosphatases↗
PubMed1989

Stimulation of erythrocyte and renal Na+,K+-adenosine triphosphatase activity by antidigoxin antibody in normal rats.

1. A circulating ouabain-like factor which inhibits the Na+,K(+)-pump has been implicated in volume-expanded states. To assess the role of this putative factor in normovolaemic rats, we measured erythrocyte and renal Na+,K(+)-adenosine triphosphatase activity after the infusion of a mixture of high-affinity digoxin-binding Fab fragments (Digibind) capable of removing digoxin from pump sites. 2. Compared with either saline (vehicle) or sheep immunoglobin G, infusion of the antidigoxin antibody caused a moderate increase of Na+,K(+)-adenosine triphosphatase activity in the erythrocyte (saline 348 +/- 12; immunoglobulin G 339 +/- 16; antidigoxin antibody 432 +/- 22 nmol h-1 mg-1; P less than 0.005 by analysis of variance) and a larger increase in the renal cortex (saline 9.7 +/- 0.9; immunoglobulin G 9 +/- 1.4; antidigoxin antibody 24.3 +/- 1.8 mumol h-1 mg-1; P less than 0.0005 by analysis of variance) without a change in blood pressure. 3. These results are consistent with the presence of a digoxin-like inhibitor of the Na+,K+-pump in normal rats.

Animals↗
PubMed2001

Platelet Na,K-adenosine triphosphatase as a tissue marker of hyperthyroidism.

Platelet Na(+),K(+)-adenosine triphosphatase (ATPase) activity was measured in 34 (15 males, 19 females) healthy subjects, 89 (35 males, 54 females) hyperthyroid patients, and 34 (7 males, 27 females) treated hyperthyroid patients to assess the potential of this measurement as a tissue marker and diagnostic test for hyperthyroidism. Platelet Na(+),K(+)-ATPase activity was measured in platelet lysates by the rate of release of phosphate from adenosine triphosphate (ATP) in the presence and absence of ouabain. Platelet Na(+),K(+)-ATPase activity (median and range) in the hyperthyroid group (271, 169 to 821 pmol/h/g protein) was significantly higher compared with the healthy group (125, 74 to 185 micromol/h/g protein, P <.001 by Mann-Whitney U test). The treated hyperthyroid group had slightly, but significantly higher, free triiodothyronine (FT3) and free thyroxine (FT4), as well as platelet Na(+),K(+)-ATPase activity (147, 98 to 246 micromol/h/g protein, P <.05). If a platelet Na(+),K(+)-ATPase activity of 190 micromol/h/g protein was used as a cut off value, the specificity and sensitivity were 90% and 93%, respectively. We conclude that platelet Na(+),K(+)-ATPase may be a useful tissue marker of hyperthyroidism.

Adolescent↗
PubMed1976

Specific sodium-22 binding to a purified sodium + potassium adenosine triphosphatase. Inhibition by ouabain.

Analysis of sodium-22 binding to purified sodium + potassium ion-activated adenosine triphosphatase (Na+, K+)-ATPase reveals the presence of two classes of binding sites. The higher affinity site (Kd = 0.2 mM) binds 6 to 7 nmol of sodium per mg of protein. Pretreatment of (Na+, K+)-ATPase with ouabain blocks the binding of sodium to this higher affinity site. Neither heat-denatured enzyme nor phospholipids extracted from the (Na+, K+)-ATPase contain a ouabain-inhibitable, higher affinity sodium binding site. The ouabain enzyme complex therefore appears to contain altered binding sites for cations.

Adenosine Triphosphatases↗
PubMed1988

Human myocardial adenosine triphosphatase activities in health and heart failure.

This study was designed to determine: (1) the myocardial adenosine triphosphatase (ATPase) activities of normal humans and patients with dilated cardiomyopathy and (2) whether ATPase activity is related to age, cause and severity of heart failure, and digitalis therapy. Endomyocardial biopsies were performed in 32 subjects. Results from six were normal. Ventricular failure in the other 26 was idiopathic (n = 15), familial (n = 3), alcohol induced (n = 5), or related to doxorubicin therapy (n = 3). The biopsies were analyzed for total, mitochondrial, Na+-K+, Ca++, and Mg++ ATPase activities. Total and mitochondrial ATPase activities correlated with left ventricular ejection fraction (r = 0.65 and 0.67, respectively; both p = 0.0001). Residual Mg++ ATPase activity correlated weakly with ventricular function as measured by echocardiography (p = 0.05). Na+-K+ ATPase activity was depressed in patients receiving digitalis (p = 0.01). These results suggest that progressive ventricular dysfunction may be associated with a progressive loss of total ATPase, mitochondrial ATPase and, to a lesser extent, Mg++ ATPase activity. Although depressed mitochondrial ATPase activity is not likely to be the primary cause of ventricular dysfunction, it could perpetuate failure by leading to inadequate production of adenosine triphosphate. Further study of ATPase activities may provide additional insight into the pathogenesis of cardiac failure.

Adenosine Triphosphatases↗
PubMed1984

State of aggregation of detergent-solubilized sarcoplasmic reticulum adenosine triphosphatase investigated by high-performance liquid chromatography.

The state of aggregation of purified sarcoplasmic reticulum adenosine triphosphatase (ATPase) was investigated by high-performance liquid chromatography (LKB TSK-G 4000 SW column) in the presence of various detergents: sodium dodecylsulphate, dodecyl octaethylene glycol monoether (C12E8), sodium deoxycholate, Triton X-100 and myristoylglycerophosphocholine. When the protein (5 mg ml-1) was solubilized with detergent (2 mg per mg protein) and the column was equilibrated with 1 mg ml-1 of the respective detergent, a molecular weight for the monomeric ATPase protein ranging from 100,000 to 200,000 was obtained. In addition to the monomeric form, significant amounts (more than 20%) of aggregated ATPase protein were observed when C12E8 or deoxycholate was used. These results are in agreement with the observation of a great tendency for self-aggregation of the ATPase protein in conventional gel filtration chromatography and ultracentrifugation experiments. The dimeric form of the ATPase protein was detected only when deoxycholate and, probably, when C12E8 was used.

Adenosine Triphosphatases↗
PubMed1972

Flagellar movement and adenosine triphosphatase activity in sea urchin sperm extracted with triton X-100.

Extraction with 0 04% (w/v) Triton X-100 removes the flagellar membrane from sea urchin sperm while leaving the motile apparatus apparently intact When reactivated in a suitable medium containing exogenous adenosine triphosphate (ATP), nearly 100% of the sperm are motile and they swim in a manner resembling that of live sperm. Under standard conditions, with 1 mM ATP at 25 degrees C, the reactivated sperm had an average frequency of 32 beats/sec and progressed forward a distance of 2.4 microm/beat; comparable figures for live sperm in seawater were 46 beats/sec and 3 9 microm/beat. The adenosine triphosphatase (ATPase) activity of the reactivated sperm was measured with a pH-stat in the presence of oligomycin to inhibit residual mitochondrial ATPase. The motile sperm had an ATPase activity of 0.16 micromole P(i)/(min x mg protein), while sperm that had been rendered non-motile by homogenizing had an activity of 0 045 micromole P(i)/(min x mg protein). The difference between the ATPase activities of the motile and nonmotile sperm was tentatively interpreted as the amount of activity coupled to movement, and under optimal conditions it amounted to about 72% of the total ATPase activity Under some conditions the movement-coupled ATPase activity was proportional to the beat frequency, but it was possibly also affected by other wave parameters. The coupled ATPase activity decreased to almost zero when movement was prevented by raising the viscosity, or by changing the pH or salt concentration. The motility of reactivated sperm was wholly dependent on the presence of ATP; other nucleotides gave very low phosphatase activity and no movement. The requirement for a divalent cation was best satisfied with Mg(++), although some motility was also obtained with Mn(++) and Ca(++). The coupled ATPase activity had a Michaelis constant (K(m)) of 0.15 mM. The beat frequency of the reactivated sperm varied with the ATP concentration, with an effective "K(m)" of 0.2 mM.

Adenosine Triphosphatases↗