scholarly journals Cation-Anion Balance during Potassium and Sodium Absorption by Barley Roots

1963 ◽  
Vol 46 (3) ◽  
pp. 369-386 ◽  
Author(s):  
P. C. Jackson ◽  
H. R. Adams
Keyword(s):  
Steady State ◽  
External Solution ◽  
Potassium Ion ◽  
Sodium Ion ◽  
The Other ◽  
Sodium Absorption ◽  
Specific Rate ◽  
Sodium Ions ◽  
Ion Absorption ◽  
Rate Limiting

Steady-state rates of potassium ion and sodium ion absorption by excised barley roots accompanied by various anions were compared with the rates of anion absorption and the concomitant H+ and base release by the roots. The cation absorption rates were found to be independent of the identities, concentrations, and rates of absorption of the anions of the external solution, including bicarbonate. Absorption of the anion of the salt plus bicarbonate could not account for the cation absorption. H+ is released during cation absorption and base during anion absorption. The magnitude by which one or the other predominates depends on the relative rates of anion and cation absorption under various conditions of pH, cation and anion concentration, and inhibitor concentrations. The conclusion is that potassium and sodium ions are absorbed independently of the anions of the absorption solution in exchange for H+, while anions are exchanged for a base. The H+ release reflects a specificity between K+ and Na+ absorption such that it appears to be H+ exchanged in the specific rate-limiting reactions of the cation absorption.

scholarly journals Resolution of Pump and Leak Components of Sodium and Potassium Ion Transport in Human Erythrocytes

1967 ◽  
Vol 50 (5) ◽  
pp. 1201-1220 ◽  
Author(s):  
R. L. Post ◽  
C. D. Albright ◽  
K. Dayani
Keyword(s):  
Cardiac Glycoside ◽  
Potassium Ion ◽  
Sodium Ion ◽  
The Other ◽  
Potassium Ions ◽  
Sodium Ions ◽  
Passive Transport ◽  
Potassium Ion Transport ◽  
Pump Activity ◽  
Sodium And Potassium

Further support for the pump-leak concept was obtained. Net transport was resolved into pump and leak components with the cardiac glycoside, ouabain. The specificity of ouabain as a pump inhibitor was demonstrated by its ineffectiveness when the pump was already inhibited by lack of one of the three pump substrates, sodium ion, potassium ion, or adenosine triphosphate. In the presence of ouabain the rates of passive transport of sodium and potassium ions changed almost in proportion to changes in their extracellular concentrations when one ion was exchanged for the other. In the presence of ouabain and at the extracellular concentrations which produced zero net transport, the ratio of potassium ions to sodium ions was 1.2-fold higher inside the cells than outside. This finding was attributed to a residual pump activity of less than 2% of capacity. The permeability to potassium ions was 10% greater than the permeability to sodium ions. A test was made of the independence of pump and leak. Conditions were chosen to change the rate through each pathway separately or in combination. When both pathways were active, net transport was the sum of the rates observed when each acted separately. A ratio of three sodium ions pumped outward per two potassium ions pumped inward was confirmed.

FURTHER STUDIES ON THE BINDING OF γ-AMINOBUTYRIC ACID BY BRAIN

1967 ◽  
Vol 45 (12) ◽  
pp. 1795-1807 ◽  
Author(s):  
Paula Strasberg ◽  
K. A. C. Elliott
Keyword(s):  
Rat Brain ◽  
Mitochondrial Fraction ◽  
Sodium Ion ◽  
The Other ◽  
Aminobutyric Acid ◽  
Sodium Ions ◽  
Ninhydrin Reaction ◽  
Gaba Content

Factors which can interfere with the paper chromatographic – ninhydrin method for determining γ-aminobutyric acid (GABA) are described. The GABA–ninhydrin reaction does not involve loss of CO2. GABA that is occluded in subcellular particles in plain sucrose homogenates of rat brain does not readily exchange with radioactive GABA in solution. The relevant particles are found mostly in the "mitochondrial fraction". These particles deteriorate with time and manipulations, and tend to lose much of their GABA content. The presence of sodium (but not of potassium, calcium, or magnesium) in the suspending medium allows considerably more GABA to be bound. The extra bound GABA is exchangeable with free labelled GABA. Sodium also promotes some exchange between free and occluded GABA. It is concluded from the present and previous results that in brain in vivo very little GABA exists in a freely diffusing situation. There are two forms of bound GABA. One of these is an occluded or storage form which does not readily exchange with free GABA though exchange is to some extent promoted by sodium ions. The other is a form which occurs only in the presence of sodium ion and is freely exchangeable with GABA in solution.

scholarly journals An Analysis of the Leakages of Sodium Ions into and Potassium Ions out of Striated Muscle Cells

1973 ◽  
Vol 61 (2) ◽  
pp. 222-250 ◽  
Author(s):  
R. A. Sjodin ◽  
L. A. Beaugé
Keyword(s):  
Steady State ◽  
Striated Muscle ◽  
Ringer Solution ◽  
Intracellular Sodium ◽  
Sodium Ion ◽  
Ion Concentration ◽  
Sodium Ions ◽  
Sodium Influx ◽  
Potassium Efflux ◽  
Steady State Balance

Net sodium influx under K-free conditions was independent of the intracellular sodium ion concentration, [Na]i, and was increased by ouabain. Unidirectional sodium influx was the sum of a component independent of [Na]i and a component that increased linearly with increasing [Na]i. Net influx of sodium ions in K-free solutions varied with the external sodium ion concentration, [Na]o, and a steady-state balance of the sodium ion fluxes occurred at [Na]o = 40 mM. When solutions were K-free and contained 10-4 M ouabain, net sodium influx varied linearly with [Na]o and a steady state for the intracellular sodium was observed at [Na]o = 13 mM. The steady state observed in the presence of ouabain was the result of a pump-leak balance as the external sodium ion concentration with which the muscle sodium would be in equilibrium, under these conditions, was 0.11 mM. The rate constant for total potassium loss to K-free Ringer solution was independent of [Na]i but dependent on [Na]o. Replacing external NaCl with MgCl2 brought about reductions in net potassium efflux. Ouabain was without effect on net potassium efflux in K-free Ringer solution with [Na]o = 120 mM, but increased potassium efflux in a medium with NaCl replaced by MgCl2. When muscles were enriched with sodium ions, potassium efflux into K-free, Mg++-substituted Ringer solution fell to around 0.1 pmol/cm2·s and was increased 14-fold by addition of ouabain.

scholarly journals The effect of methanol and dioxan on the rates of the β-galactosidase-catalysed hydrolyses of some β-d-galactopyranosides: rate-limiting degalactosylation. The pH-dependence of galactosylation and degalactosylation

1973 ◽  
Vol 133 (1) ◽  
pp. 81-87 ◽  
Author(s):  
Michael L. Sinnott ◽  
Odile M. Viratelle
Keyword(s):  
Steady State ◽  
Ph Dependence ◽  
Methanol Concentration ◽  
The Other ◽  
Fractional Rate ◽  
Rate Of Increase ◽  
Rate Limiting ◽  
Hydrolysis Of

1. The effect of methanol on the β-galactosidase-catalysed hydrolysis of some nitrophenyl β-d-galactopyranosides has been studied under steady-state conditions. 2. The initial fractional rate of increase of kcat. as a function of methanol concentration with 2,4- and 3,5-dinitrophenyl β-d-galactopyranosides, but not with the other substrates studied, indicated that degalactosylation of the enzyme was rate-limiting. 3. The decrease in kcat. at high methanol concentrations for these substrates is considered to arise from causes other than galactosylation becoming rate-limiting. 4. Both galactosylation and degalactosylation of the enzyme require protonation of a group of pKa approx. 9.

Fidelity of J1269 and J24523

2007 ◽  
Vol 35 (2) ◽  
pp. 94-117 ◽  
Author(s):  
James A. Popio ◽  
John R. Luchini
Keyword(s):  
Steady State ◽  
Rolling Resistance ◽  
Test Methods ◽  
The Other ◽  
Reference Condition ◽  
Test Standards

Abstract This study compares data from the two Society of Automotive Engineers test methods for rolling resistance: J-2452 (Stepwise Coast-Down) and J-1269 (Equilibrium) steady state. The ability of the two methods to evaluate tires was examined by collecting data for 12 tires. The data were analyzed and the data showed that the two methods ranked the tires the same after the data were regressed and the rolling resistance magnitude was calculated at the Standard Reference Condition. In addition, analysis of the two methods using this matched set of testing provided an opportunity to evaluate each of these test standards against the other. It was observed that each test has merits absent from the other.

Kinetic analysis of mechanism of intestinal Na+-dependent sugar transport

1985 ◽  
Vol 248 (5) ◽  
pp. C498-C509 ◽  
Author(s):  
D. Restrepo ◽  
G. A. Kimmich
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Sugar Transport ◽  
Enzyme Kinetic ◽  
Steady State Distribution ◽  
State Distribution ◽  
Least Squares Fit ◽  
Coupling Stoichiometry ◽  
Rate Limiting ◽  
Kinetics Of

Zero-trans kinetics of Na+-sugar cotransport were investigated. Sugar influx was measured at various sodium and sugar concentrations in K+-loaded cells treated with rotenone and valinomycin. Sugar influx follows Michaelis-Menten kinetics as a function of sugar concentration but not as a function of Na+ concentration. Nine models with 1:1 or 2:1 sodium:sugar stoichiometry were considered. The flux equations for these models were solved assuming steady-state distribution of carrier forms and that translocation across the membrane is rate limiting. Classical enzyme kinetic methods and a least-squares fit of flux equations to the experimental data were used to assess the fit of the different models. Four models can be discarded on this basis. Of the remaining models, we discard two on the basis of the trans sodium dependence and the coupling stoichiometry [G. A. Kimmich and J. Randles, Am. J. Physiol. 247 (Cell Physiol. 16): C74-C82, 1984]. The remaining models are terter ordered mechanisms with sodium debinding first at the trans side. If transfer across the membrane is rate limiting, the binding order can be determined to be sodium:sugar:sodium.

scholarly journals Receptor-operated Ca2+ channels in gastric parietal cells: gastrin and carbachol induce Ca2+ influx in depleting intracellular Ca2+ stores

1993 ◽  
Vol 289 (1) ◽  
pp. 117-124 ◽  
Author(s):  
S Roche ◽  
J P Bali ◽  
R Magous
Keyword(s):  
Steady State ◽  
Receptor Activation ◽  
Parietal Cells ◽  
The Other ◽  
Bivalent Cation ◽  
Gtp Binding ◽  
Gastric Parietal Cells ◽  
Type Receptor ◽  
Ca2 Channels ◽  
Stimulation Of

The mechanism whereby gastrin-type receptor and muscarinic M3-type receptor regulate free intracellular Ca2+ concentration ([Ca2+]i) was studied in rabbit gastric parietal cells stimulated by either gastrin or carbachol. Both agonists induced a biphasic [Ca2+]i response: a transient [Ca2+]i rise, followed by a sustained steady state depending on extracellular Ca2+. Gastrin and carbachol also caused a rapid and transient increase in Mn2+ influx (a tracer for bivalent-cation entry). Pre-stimulation of cells with one agonist drastically decreased both [Ca2+]i increase and Mn2+ influx induced by the other. Neither diltiazem nor pertussistoxin treatment had any effect on agonist-stimulated Mn2+ entry. Thapsigargin, a Ca(2+)-pump inhibitor, induced a biphasic [Ca2+]i increase, and enhanced the rate of Mn2+ entry. Preincubation of cells with thapsigargin inhibits the [Ca2+]i increase as well as Mn2+ entry stimulated by gastrin or by carbachol. Thapsigargin induced a weak but significant increase in Ins(1,4,5)P3 content, but this agent had no effect on the agonist-evoked Ins(1,4,5)P3 response. In permeabilized parietal cells, Ins(1,4,5)P3 and caffeine caused an immediate Ca2+ release from intracellular pools, followed by a reloading of Ca2+ pools which can be prevented in the presence of thapsigargin. We conclude that (i) gastrin and carbachol mobilize common Ca2+ intracellular stores, (ii) Ca2+ permeability secondary to receptor activation involves neither a voltage-sensitive Ca2+ channel nor a GTP-binding protein from the G1 family, and (iii) agonists regulate common Ca2+ channels in depleting intracellular Ca2+ stores.

Recent advances in ferromagnetic metal sulfides and selenides as anodes for sodium- and potassium-ion batteries

2021 ◽  
Author(s):  
Yuhan Wu ◽  
Chenglin Zhang ◽  
Huaping Zhao ◽  
Yong Lei
Keyword(s):  
Lithium Ion Batteries ◽  
Lithium Ion ◽  
Rechargeable Batteries ◽  
Potassium Ion ◽  
Sodium Ion ◽  
Metal Sulfides ◽  
Sodium Ion Batteries ◽  
Next Generation ◽  
Cost Competitiveness ◽  
Sodium And Potassium

In next-generation rechargeable batteries, sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have been considered as attractive alternatives to lithium-ion batteries due to their cost competitiveness. Anodes with complicated electrochemical mechanisms...

Co-construction of sulfur vacancies and carbon confinement in V5S8/CNFs to induce an ultra-stable performance for half/full sodium-ion and potassium-ion batteries

Nanoscale ◽  
2021 ◽  
Author(s):  
Lihong Xu ◽  
Xiaochuan Chen ◽  
Wenti Guo ◽  
Lingxing Zeng ◽  
Tao Yang ◽  
...  
Keyword(s):  
Carbon Fibers ◽  
Anode Materials ◽  
High Energy ◽  
Potassium Ion ◽  
Sodium Ion ◽  
Sodium Ion Batteries ◽  
Vanadium Sulfide ◽  
Stable Performance

To construct anode materials for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) with high energy, and long lifespan is significant and still challenging. Here, sulfur-defective vanadium sulfide/carbon fibers composite (D-V5S8/CNFs)...

POVERTY TRAPS AND INFERIOR GOODS IN A DYNAMIC HECKSCHER–OHLIN MODEL

2012 ◽  
Vol 17 (6) ◽  
pp. 1227-1251 ◽  
Author(s):  
Eric W. Bond ◽  
Kazumichi Iwasa ◽  
Kazuo Nishimura
Keyword(s):  
Economic Theory ◽  
Steady State ◽  
World Economy ◽  
Steady States ◽  
The Other ◽  
Poverty Traps ◽  
Poverty Trap ◽  
Multiple Steady States ◽  
The World ◽  
State Capital

We extend the dynamic Heckscher–Ohlin model in Bond et al. [Economic Theory(48, 171–204, 2011)] and show that if the labor-intensive good is inferior, then there may exist multiple steady states in autarky and poverty traps can arise. Poverty traps for the world economy, in the form of Pareto-dominated steady states, are also shown to exist. We show that the opening of trade can have the effect of pulling the initially poorer country out of a poverty trap, with both countries having steady state capital stocks exceeding the autarky level. However, trade can also pull an initially richer country into a poverty trap. These possibilities are a sharp contrast with dynamic Heckscher–Ohlin models with normality in consumption, where the country with the larger (smaller) capital stock than the other will reach a steady state where the level of welfare is higher (lower) than in the autarkic steady state.

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