Lack of effect of acute alcohol ingestion on erythrocyte Na+, K+ -ATPase activity or passive sodium uptake in vivo in man.

1986 ◽  
Vol 47 (6) ◽  
pp. 489-494 ◽  
Author(s):  
I B Puddey ◽  
L J Beilin ◽  
R Vandongen
Keyword(s):  
Atpase Activity ◽  
Alcohol Ingestion ◽  
Sodium Uptake

scholarly journals Dissection of Swa2p/Auxilin Domain Requirements for Cochaperoning Hsp70 Clathrin-uncoating Activity In Vivo

2006 ◽  
Vol 17 (7) ◽  
pp. 3281-3290 ◽  
Author(s):  
Jing Xiao ◽  
Leslie S. Kim ◽  
Todd R. Graham
Keyword(s):  
Atpase Activity ◽  
Point Mutation ◽  
Mutational Analysis ◽  
Weak Interactions ◽  
Tetratricopeptide Repeat ◽  
Uba Domain ◽  
J Domain ◽  
Tpr Domain

The auxilin family of J-domain proteins load Hsp70 onto clathrin-coated vesicles (CCVs) to drive uncoating. In vitro, auxilin function requires its ability to bind clathrin and stimulate Hsp70 ATPase activity via its J-domain. To test these requirements in vivo, we performed a mutational analysis of Swa2p, the yeast auxilin ortholog. Swa2p is a modular protein with three N-terminal clathrin-binding (CB) motifs, a ubiquitin association (UBA) domain, a tetratricopeptide repeat (TPR) domain, and a C-terminal J-domain. In vitro, clathrin binding is mediated by multiple weak interactions, but a Swa2p truncation lacking two CB motifs and the UBA domain retains nearly full function in vivo. Deletion of all CB motifs strongly abrogates clathrin disassembly but does not eliminate Swa2p function in vivo. Surprisingly, mutation of the invariant HPD motif within the J-domain to AAA only partially affects Swa2p function. Similarly, a TPR point mutation (G388R) causes a modest phenotype. However, Swa2p function is abolished when these TPR and J mutations are combined. The TPR and J-domains are not functionally redundant because deletion of either domain renders Swa2p nonfunctional. These data suggest that the TPR and J-domains collaborate in a bipartite interaction with Hsp70 to regulate its activity in clathrin disassembly.

Metabolic importance of Na+/K+-ATPase activity during sea urchin development.

1997 ◽  
Vol 200 (22) ◽  
pp. 2881-2892 ◽  
Author(s):  
P Leong ◽  
D Manahan
Keyword(s):  
Enzyme Activity ◽  
Atpase Activity ◽  
Sea Urchin ◽  
Sodium Pump ◽  
Sea Water ◽  
Strongylocentrotus Purpuratus ◽  
Lytechinus Pictus ◽  
Stimulation Of

Early stages of animal development have high mass-specific rates of metabolism. The biochemical processes that establish metabolic rate and how these processes change during development are not understood. In this study, changes in Na+/K+-ATPase activity (the sodium pump) and rate of oxygen consumption were measured during embryonic and early larval development for two species of sea urchin, Strongylocentrotus purpuratus and Lytechinus pictus. Total (in vitro) Na+/K+-ATPase activity increased during development and could potentially account for up to 77 % of larval oxygen consumption in Strongylocentrotus purpuratus (pluteus stage) and 80 % in Lytechinus pictus (prism stage). The critical issue was addressed of what percentage of total enzyme activity is physiologically active in living embryos and larvae and thus what percentage of metabolism is established by the activity of the sodium pump during development. Early developmental stages of sea urchins are ideal for understanding the in vivo metabolic importance of Na+/K+-ATPase because of their small size and high permeability to radioactive tracers (86Rb+) added to sea water. A comparison of total and in vivo Na+/K+-ATPase activities revealed that approximately half of the total activity was utilized in vivo. The remainder represented a functionally active reserve that was subject to regulation, as verified by stimulation of in vivo Na+/K+-ATPase activity in the presence of the ionophore monensin. In the presence of monensin, in vivo Na+/K+-ATPase activities in embryos of S. purpuratus increased to 94 % of the maximum enzyme activity measured in vitro. Stimulation of in vivo Na+/K+-ATPase activity was also observed in the presence of dissolved alanine, presumably due to the requirement to remove the additional intracellular Na+ that was cotransported with alanine from sea water. The metabolic cost of maintaining the ionic balance was found to be high, with this process alone accounting for 40 % of the metabolic rate of sea urchin larvae (based on the measured fraction of total Na+/K+-ATPase that is physiologically active in larvae of S. purpuratus). Ontogenetic changes in pump activity and environmentally induced regulation of reserve Na+/K+-ATPase activity are important factors that determine a major proportion of the metabolic costs of sea urchin development.

Thyroid hormone control of Na+-K+-ATPase and K+-dependent phosphatase in rat heart

1977 ◽  
Vol 232 (5) ◽  
pp. C196-C201 ◽  
Author(s):  
K. D. Philipson ◽  
I. S. Edelman
Keyword(s):  
Thyroid Hormone ◽  
Atpase Activity ◽  
Weight Ratio ◽  
Heart Weight ◽  
Reverse T3 ◽  
Na Pump ◽  
Hormone Control ◽  
Rat Ventricle

To assess the possible role of the Na+ pump in mediating physiological responses to thyroid hormone in the rat myocardium, we examined the effects of L-3,5,3'-triiodothyronine (T3) on the activities of the closely associated enzymes, Na+-K+-dependent adenosine triphosphatase (Na-K-ATPase) and K+-dependent p-nitrophenyl phosphatase (K-dep-pNPPase). In hypothyroid rats, administration of T3 (50 microng/100 g body wt) resulted in significant increases (greater than 50%) in Na-K-ATPase and K-dep-pNPPase activities in both crude homogenates and microsomal fractions of the rat ventricle. Significant effects on Na-K-ATPase activity were also attained with low doses (1 microng/100 g body wt) of T3. A method was developed for assaying K-dep-pNPPase activity in cardiac slices. With this technique, enhancement in K-dep-pNPPase activity of 89.2% was found in ventricle slices after treatment of hypothyroid rats with T3 (50 microng/100 g body wt), implying that augmentation of the capacity of the Na+ pump is achieved in vivo. The potent analogue, L-3,5-diiodo-3' isopropyl thyronine (isopropyl T2) had the same effects on cardiac growth and Na-K-ATPase as T3, in hypothyroid rats. In contrast, the relatively inactive isomer, L-3,3',5'-triiodothyronine (reverse T3) had no significant effect on the heart weight-to-body weight ratio or on ventricular Na-K-ATPase activity.

scholarly journals Dynamic regulation of extracellular ATP in Escherichia coli

2017 ◽  
Vol 474 (8) ◽  
pp. 1395-1416 ◽  
Author(s):  
Cora Lilia Alvarez ◽  
Gerardo Corradi ◽  
Natalia Lauri ◽  
Irene Marginedas-Freixa ◽  
María Florencia Leal Denis ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Atpase Activity ◽  
Atp Release ◽  
Membrane Vesicles ◽  
Fold Increase ◽  
Extracellular Atp ◽  
Outer Membrane Vesicles ◽  
Dynamic Regulation ◽  
E Coli

We studied the kinetics of extracellular ATP (ATPe) in Escherichia coli and their outer membrane vesicles (OMVs) stimulated with amphipatic peptides melittin (MEL) and mastoparan 7 (MST7). Real-time luminometry was used to measure ATPe kinetics, ATP release, and ATPase activity. The latter was also determined by following [32P]Pi released from [γ-32P]ATP. E. coli was studied alone, co-incubated with Caco-2 cells, or in rat jejunum segments. In E. coli, the addition of [γ-32P]ATP led to the uptake and subsequent hydrolysis of ATPe. Exposure to peptides caused an acute 3-fold (MST7) and 7-fold (MEL) increase in [ATPe]. In OMVs, ATPase activity increased linearly with [ATPe] (0.1–1 µM). Exposure to MST7 and MEL enhanced ATP release by 3–7 fold, with similar kinetics to that of bacteria. In Caco-2 cells, the addition of ATP to the apical domain led to a steep [ATPe] increase to a maximum, with subsequent ATPase activity. The addition of bacterial suspensions led to a 6–7 fold increase in [ATPe], followed by an acute decrease. In perfused jejunum segments, exposure to E. coli increased luminal ATP 2 fold. ATPe regulation of E. coli depends on the balance between ATPase activity and ATP release. This balance can be altered by OMVs, which display their own capacity to regulate ATPe. E. coli can activate ATP release from Caco-2 cells and intestinal segments, a response which in vivo might lead to intestinal release of ATP from the gut lumen.

Na-K-ATPase activity along the rabbit, rat, and mouse nephron

1979 ◽  
Vol 237 (2) ◽  
pp. F114-F120 ◽  
Author(s):  
A. I. Katz ◽  
A. Doucet ◽  
F. Morel
Keyword(s):  
Atpase Activity ◽  
Thick Ascending Limb ◽  
Sensitivity Limit ◽  
Henle's Loop ◽  
Collecting Tubule ◽  
Pars Recta ◽  
Hydrolysis Of ◽  
Total Enzyme

Na-K-ATPase activity along the rabbit, rat, and mouse nephron was determined with a micromethod that measures directly labeled phosphate released by the hydrolysis of [gamma-32P]ATP. Na-K-ATPase activity was highest in the rat, intermediate in the mouse, and lowest in the rabbit nephron. With the exception of rabbit cortical thick ascending limb, the enzyme profile was similar in the three species: Na-K-ATPase activity per millimeter tubule length was highest in the distal convoluted tubule and thick ascending limb of Henle's loop, intermediate in the proximal convoluted tubule, and lowest in the pars recta and collecting tubule. The enzyme was present in the thin limbs of Henle's loop, but its activity was very low and measurements were close to the sensitivity limit of the method. Both the absolute activity and the fraction of the total enzyme represented by Na-K-ATPase were severalfold higher than in kidney homogenates. Finally, the Na-K-ATPase activity measured in certain segments of the rat and rabbit nephron in this study seems sufficient to account in theory for the active component of the net sodium transport found in the corresponding region of the nephron with either in vivo or in vitro single tubule microperfusion techniques.

Effect of ethanol on phospholipid metabolism by the rat lung

1975 ◽  
Vol 229 (5) ◽  
pp. 1316-1320 ◽  
Author(s):  
M Wagner ◽  
HO Heinemann
Keyword(s):  
Palmitic Acid ◽  
Phospholipid Metabolism ◽  
Alcohol Ingestion ◽  
Rat Lung

Prefeeding of alcohol shows the in vivo incorporation of orally administered palmitic acid into phosphatidylcholine of the lung. This impairment is also demonstrable in vitro utilizing lung slices and 14C-labeled palmitate or cytidine 5'-diphosphocholine as precursors. It is concluded that alcohol ingestion affects the utilization of precursors needed for phospholipid formation in the lung.

scholarly journals Short-term K+ deprivation provokes insulin resistance of cellular K+ uptake revealed with the K+ clamp

2001 ◽  
Vol 280 (1) ◽  
pp. F95-F102 ◽  
Author(s):  
Cheol S. Choi ◽  
Curtis B. Thompson ◽  
Patrick K. K. Leong ◽  
Alicia A. McDonough ◽  
Jang H. Youn
Keyword(s):  
Insulin Resistance ◽  
Atpase Activity ◽  
Infusion Rate ◽  
Insulin Action ◽  
Insulin Dose ◽  
Short Term ◽  
Conscious Rat ◽  
Physiological Concentration ◽  
Glucose Clearance

We aimed to test the feasibility of quantifying insulin action on cellular K+ uptake in vivo in the conscious rat by measuring the exogenous K+ infusion rate needed to maintain constant plasma K+ concentration ([K+]) during insulin infusion. In this “K+ clamp” the K+ infusion rate required to clamp plasma [K+] is a measure of insulin action to increase net plasma K+ disappearance. K+ infusion rate required to clamp plasma [K+] was insulin dose dependent. Renal K+ excretion was not significantly affected by insulin at a physiological concentration (∼90 μU/ml, P > 0.05), indicating that most of insulin-mediated plasma K+ disappearance was due to K+ uptake by extrarenal tissues. In rats deprived of K+ for 2 days, plasma [K+] fell from 4.2 to 3.8 mM, insulin-mediated plasma glucose clearance was normal, but insulin-mediated plasma K+ disappearance decreased to 20% of control, even though there was no change in muscle Na-K-ATPase activity or expression, which is believed to be the main K+ uptake route. After 10 days K+ deprivation, plasma [K+] fell to 2.9 mM, insulin-mediated K+ disappearance decreased to 6% of control (glucose clearance normal), and there were 50% decreases in Na-K-ATPase activity and α2-subunit levels. In conclusion, the present study proves the feasibility of the K+ clamp technique and demonstrates that short-term K+ deprivation leads to a near complete insulin resistance of cellular K+uptake that precedes changes in muscle sodium pump expression.

Endogenous vasopressin regulates Na-K-ATPase and Na+-K+-Cl− cotransporterrbsc-1 in rat outer medulla

2002 ◽  
Vol 282 (2) ◽  
pp. F265-F270 ◽  
Author(s):  
Claudia A. Bertuccio ◽  
Fernando R. Ibarra ◽  
Jorge E. Toledo ◽  
Elvira E. Arrizurieta ◽  
Rodolfo S. Martin
Keyword(s):  
Renal Failure ◽  
Chronic Renal Failure ◽  
Atpase Activity ◽  
Receptor Antagonist ◽  
The Other ◽  
Outer Medulla ◽  
Physiological Conditions ◽  
Increased Activity ◽  
Expression And Activity

Previous reports have shown a stimulatory effect of vasopressin (VP) on Na-K-ATPase and rBSC-1 expression and activity. Whether these VP-dependent mechanisms are operating in vivo in physiological conditions as well as in chronic renal failure (CRF) has been less well studied. We measured ATPase expression and activity and rBSC-1 expression in the outer medulla of controls and moderate CRF rats both before and under in vivo inhibition of VP by OPC-31260, a selective V2-receptor antagonist. OPC-31260 decreased Na-K-ATPase activity from 11.2 ± 1.5 to 3.7 ± 0.8 in controls ( P < 0.05) and from 19.0 ± 0.8 to 2.9 ± 0.5 μmol Pi · mg protein−1 · h−1 in moderate CRF rats ( P < 0.05). CRF was associated with a significant increase in Na-K-ATPase activity ( P < 0.05). Similarly, CRF was also associated with a significant increase in Na-K-ATPase expression to 164.4 ± 21.5% compared with controls ( P < 0.05), and OPC-31260 decreased Na-K-ATPase expression in both controls and CRF rats to 57.6 ± 9.5 and 105.3 ± 10.9%, respectively ( P < 0.05). On the other hand, OPC-31260 decreased rBSC-I expression in both controls and CRF rats to 60.8 ± 6.5 and 30.0 ± 6.9%, respectively ( P < 0.05), and was not influenced by CRF (95.7 ± 5.2%). We conclude that 1) endogenous VP modulated Na-K-ATPase and rBSC-1 in both controls and CRF; and 2) CRF was associated with increased activity and expression of the Na-K-ATPase in the outer medulla, in contrast to the unaltered expression of the rBSC-1. The data suggest that endogenous VP could participate in the regulation of electrolyte transport at the level of the outer medulla.

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