scholarly journals Ouabain binding to phospholipid-dependent adenosine triphosphatase

1978 ◽  
Vol 169 (2) ◽  
pp. 313-320 ◽  
Author(s):  
S L Goodman ◽  
K P Wheeler
Keyword(s):  
Atpase Activity ◽  
Protein Complex ◽  
Adenosine Triphosphatase ◽  
Rabbit Kidney ◽  
Ouabain Binding ◽  
Equilibrium Conditions ◽  
Enzyme Preparations

The role of phospholipid in the binding of ouabain to the (Na+ + K+)-dependent adenosine triphosphatase was studied. Enzyme preparations obtained from rabbit kidney were treated with Lubrol WX to remove the phospholipid component essential for ATPase activity. Reconstituted enzyme samples were prepared by the addition of phosphatidylserine and sedimentation of an enzymically active lipid-protein complex. The binding of ouabain to both kinds of preparations was measured under equilibrium conditions with the use of 3H-labelled ouabain and initial ouabain concentrations in the range 0.01-1 micrometer. The main findings were: (i) (Mg2+ + Pi) promoted binding of significant quantities of ouabain only to the reconstituted enzyme; (ii) the absence of added Na+, (Mg2+ + ATP) similarly promoted binding only to the reconstituted samples; (iii) the addition of Na+ in the presence of (Mg2+ + ATP) increased the amount of ouabain bound to the reconstituted enzyme when the ouabain concentration was below about 0.1 micrometer, but it had no effect when the ouabain concentration was about 1 micrometer; (iv) (Mg2+ + ATP) induced ouabain binding to the depleted enzyme only when Na+ was also added; (v) the amount of ouabain bound to both depleted and reconstituted enzymes was the same in the presence of (Mg2+ + ATP + Na+); (vi) the reconstituted enzyme appeared to have a greater affinity for Na+ than did the depleted enzyme.

Role of Na+/K+-stimulated adenosine triphosphatase in the action of dopaminergic-D2 receptors of the liver in rats

1987 ◽  
Vol 7 (11) ◽  
pp. 839-842 ◽  
Author(s):  
Abdulrahim Abu-Jayyab ◽  
Ahmed Mahgoub
Keyword(s):  
Atpase Activity ◽  
Receptor Antagonist ◽  
Dopamine Receptor ◽  
Inhibitory Activity ◽  
Receptor Agonist ◽  
Adenosine Triphosphatase ◽  
D2 Receptors ◽  
Dopamine Receptor Agonist ◽  
Dopamine Receptor Antagonist

The dopamine receptor agonist, bromocriptine, in a dose of 10 mg/kg i.p. for 14 days, in rats caused a significant increase in liver Na+/K+-ATPase activity, whereas sulpiride, a dopamine receptor antagonist, in a dose of 10 mg/kg, i.p. for 14 days, in rats, caused a significant decrease in liver Na+/K+-ATPase activity. Injection of bromocriptine and sulpiride simultaneously in a group of rats, under the same conditions and using the same doses caused a complete block of both stimulatory activity of bromocriptine and inhibitory activity of sulpiride on liver Na+/K+-ATPase activity. It is suggested that Na+/K+-ATPase may have a role in the action of dopaminergic-D2 receptors.

UTERINE MITOSIS, ALKALINE PHOSPHATASE AND ADENOSINE TRIPHOSPHATASE DURING DEVELOPMENT AND REGRESSION OF DECIDUOMATA IN PSEUDOPREGNANT MICE

1969 ◽  
Vol 44 (1) ◽  
pp. 91-NP ◽  
Author(s):  
KATHLEEN HALL
Keyword(s):  
Alkaline Phosphatase ◽  
Atpase Activity ◽  
Vascular Endothelium ◽  
Stromal Cells ◽  
Adenosine Triphosphatase ◽  
Glandular Epithelium ◽  
Histochemical Localization ◽  
Vessel Walls ◽  
The Right

SUMMARY Incidence and patterns of mitoses and histochemical localization of alkaline phosphatase (APase) and adenosine triphosphatase (ATPase) were studied from days 5 to 20 in pseudopregnant mice in which deciduomata had been induced in the left uterine horns by intrauterine injection of oil on day 4, the right horns serving as controls. In stromal cells, mitoses were very numerous throughout the endometrium of the left (but not the right) horn on days 5 and 6, in the basal, non-decidualized stroma until day 8 or day 9, and were not seen in stromal cells of either horn thereafter. In glandular epithelium, mitoses were absent from days 5 to 10, and numerous from day 11 or 12 until at least day 17 in both horns. Mitoses were present in capillaries within developing deciduomata on days 5 and 6, then seldom seen until day 12 and during the next 3 days were numerous in endothelial and pericapillary cells in the mesometrial quadrant of the left horn and around glands in both horns. The deciduoma cells reacted strongly with AP and ATP substrates from days 5 to 10, after which the intensity of the reaction weakened and had usually disappeared by day 13. ATPase activity disappeared from vascular endothelium within the deciduoma a few hours after APase had appeared within the deciduoma cells on day 5. It reappeared in the vessel walls on day 9 and thereafter was usually present until the deciduoma was shed. In the basal, non-decidualized stroma, APase was absent until about day 10, then appeared in the stroma cells nearest to the myometrium, extending gradually into the densely packed cells nearest to the regressing deciduoma. The possible role of this enzyme in reparative growth of the endometrium after regression of the deciduoma is discussed.

Effect of changes in dietary sodium on active electrolyte transport by erythrocytes at different stages of human pregnancy

1988 ◽  
Vol 74 (2) ◽  
pp. 145-150 ◽  
Author(s):  
E. D. M. Gallery ◽  
J. Rowe ◽  
M. A. Brown ◽  
M. Ross
Keyword(s):  
Atpase Activity ◽  
Adenosine Triphosphatase ◽  
Normal Values ◽  
Sodium Intake ◽  
Post Partum ◽  
Electrolyte Transport ◽  
Dietary Sodium ◽  
Ouabain Binding ◽  
86Rb Influx ◽  
In Pregnancy

1. Active electrolyte transport was examined in erythrocytes from women in the second and third trimesters of pregnancy and post partum, and compared with that in ovulating women. 2. There was a significant reduction in intracellular sodium ([Na]i) and increase in intracellular potassium ([K]i) in pregnancy with a return towards normal values in the post-partum period. 3. Maximum specific ouabain binding [number of Na+,K+-adenosine triphosphatase (Na+,K+-ATPase) units] was increased by 70% in pregnancy and returned slowly towards normal values post partum. 4. Na+,K+-ATPase activity as determined by ouabain-sensitive 86Rb influx in artificial media was also increased in pregnancy by 13%. It returned towards normal post partum. 5. The increases in Na+,K+-ATPase in pregnancy were not closely related to the concomitant increases in aldosterone or cholesterol nor to reticulocytosis and were not affected by 7 days of high (> 250 mmol/day) or low (< 50 mmol/day) sodium intake.

scholarly journals Studies on the microsomal sodium-plus-potassium ion-stimulated adenosine triphosphatase system in rat ventral prostate

1969 ◽  
Vol 113 (5) ◽  
pp. 829-836 ◽  
Author(s):  
K. Ahmed ◽  
H G Williams-Ashman
Keyword(s):  
Atpase Activity ◽  
Adenosine Triphosphatase ◽  
Specific Activity ◽  
Reaction Medium ◽  
Ventral Prostate ◽  
Experimental Conditions ◽  
Enzyme Preparations ◽  
Rat Ventral Prostate ◽  
Stimulation Of

A Mg2++Na++K+-stimulated adenosine triphosphatase (ATPase) preparation was isolated from rat ventral prostate by flotation of microsomal membranes in high-density sucrose solutions. The reaction medium for optimum Na++K+-stimulated ATPase activity was found to be: Na+, 115mm; K+, 7–10mm; Mg2+, 3mm; ATP, 3mm; tris buffer, pH7·4 at 38°, 20mm. The average ΔPi (Mg2++Na++K+ minus Mg2++Na+) was 9μmoles/mg. of protein/hr., representing a 30% increase over the Mg2++Na+-stimulated ATPase activity. At high concentrations, K+ was inhibitory to the enzyme activity. Half-maximal inhibition of Na++K+-stimulated ATPase activity was elicited by ouabain at 0·1mm. The preparation exhibited phosphatase activity towards ribonucleoside triphosphates other than ATP. However, stimulation of Pi release by Na++K+ was observed only with ATP as substrate. The apparent Km for ATP for Na++K+-stimulated activity was about 0·3×10−3m. Ca2+ inhibited only the Na++K+-stimulated ATPase activity. Mg2+ could be replaced by Ca2+ but then no Na++K+ stimulation of ATPase activity was noticed. The addition of testosterone or dihydrotestosterone (17β-hydroxy-5α-androstan-3-one) in vitro at 0·1–10μm under a variety of experimental conditions did not significantly increase the Na++K+-stimulated ATPase activity. The enzyme preparations from prostates of orchidectomized rats, however, exhibited a drastic decrease in the specific activity of Na++K+-stimulated ATPase; these changes were prevented in the orchidectomized rats by injection of testosterone propionate.

scholarly journals Role of the subunits of the energy-transducing adenosine triphosphatase from Micrococcus lysodeikticus membranes studied by proteolytic digestion and immunological approaches

1980 ◽  
Vol 186 (3) ◽  
pp. 713-723 ◽  
Author(s):  
F Mollinedo ◽  
V Larraga ◽  
F J Coll ◽  
E Muñoz
Keyword(s):  
Atpase Activity ◽  
Adenosine Triphosphatase ◽  
Specific Activity ◽  
Relative Proportion ◽  
Inhibitory Effect ◽  
Beta Subunit ◽  
Gamma Subunit ◽  
Micrococcus Lysodeikticus ◽  
Alpha Beta

An energy-transducing adenosine triphosphatase (ATPase, EC 3.6.1.3) that contains an extra polypeptide (delta) as well as three intrinsic subunits (alpha, beta, gamma) was purified from Micrococcus lysodeikticus membranes. The apparent subunit stoichiometry of this soluble ATPase complex is alpha 3 beta 3 gamma delta. The functional role of the subunits was studied by correlating subunit sensitivity to trypsin and effect of antibodies raised against holo-ATPase and its alpha, beta and gamma subunits with changes in ATPase activity and ATPase rebinding to membranes. A form of the ATPase with the subunit proportions 1.67(alpha):3.00(beta:0.17(gamma) was isolated after trypsin treatment of purified ATPase. This form has more than twice the specific activity of native enzyme. Other forms with less relative proportion of alpha subunits and absence of gamma subunit are not active. Of the antisera to subunits, only anti-(beta-subunit) serum shows a slight inhibitory effect on ATPase activity, but its combination with either anti-(alpha-subunit) or anti-(gamma-subunit) serum increases the effect. The results suggest that beta subunit is required for full ATPase activity, although a minor proportion of alpha and perhaps gamma subunit(s) is also required, probably to impart an active conformation to the protein. The additional polypeptide not hitherto described in Micrococcus lysodeikticus ATPase had a molecular weight of 20 000 and was found to be involved in ATPase binding to membranes. This 20 000-dalton component can be equated with the delta subunit of other energy-transducing ATPases and its association with the (alpha, beta, gamma) M. lysodeikticus ATPase complex appears to be dependent on bivalent cations. The present results do not preclude the possibility that the gamma subunit also plays a role in ATPase binding, in which, however, the major subunits do not seem to play a role.

Localization of Adenosine Triphosphatase Activity in the Phleom of Nicotiana Tabacum

1972 ◽  
Vol 30 ◽  
pp. 230-231
Author(s):  
James Cronshaw ◽  
Jamison E. Gilder
Keyword(s):  
Plasma Membrane ◽  
Atpase Activity ◽  
Adenosine Triphosphatase ◽  
Higher Plants ◽  
High Surface ◽  
Root Tip ◽  
Animal Cells ◽  
Physiological Processes ◽  
Tip Cells ◽  
Atpase Localization

Adenosine triphosphatase (ATPase) activity has been shown to be associated with numerous physiological processes in both plants and animal cells. Biochemical studies have shown that in higher plants ATPase activity is high in cell wall preparations and is associated with the plasma membrane, nuclei, mitochondria, chloroplasts and lysosomes. However, there have been only a few ATPase localization studies of higher plants at the electron microscope level. Poux (1967) demonstrated ATPase activity associated with most cellular organelles in the protoderm cells of Cucumis roots. Hall (1971) has demonstrated ATPase activity in root tip cells of Zea mays. There was high surface activity largely associated with the plasma membrane and plasmodesmata. ATPase activity was also demonstrated in mitochondria, dictyosomes, endoplasmic reticulum and plastids.

scholarly journals Endogenous Mammalian Cardiotonic Steroids—A New Cardiovascular Risk Factor?—A Mini-Review

Life ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 727
Author(s):  
Natalia Słabiak-Błaż ◽  
Grzegorz Piecha
Keyword(s):  
Adenosine Triphosphatase ◽  
Therapeutic Strategies ◽  
Structure And Function ◽  
Sodium Potassium ◽  
Sodium Homeostasis ◽  
Cardiovascular Tissue ◽  
Ancient Times ◽  
And Function ◽  
Regulation Of Blood Pressure

The role of endogenous mammalian cardiotonic steroids (CTS) in the physiology and pathophysiology of the cardiovascular system and the kidneys has interested researchers for more than 20 years. Cardiotonic steroids extracted from toads or plants, such as digitalis, have been used to treat heart disease since ancient times. CTS, also called endogenous digitalis-like factors, take part in the regulation of blood pressure and sodium homeostasis through their effects on the transport enzyme called sodium–potassium adenosine triphosphatase (Na/K-ATPase) in renal and cardiovascular tissue. In recent years, there has been increasing evidence showing deleterious effects of CTS on the structure and function of the heart, vasculature and kidneys. Understanding the role of CTS may be useful in the development of potential new therapeutic strategies.

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