scholarly journals Sodium Movements in the Human Red Blood Cell

1970 ◽  
Vol 56 (3) ◽  
pp. 322-341 ◽  
Author(s):  
John R. Sachs
Keyword(s):  
Blood Cell ◽  
Rate Constant ◽  
Transport Mechanism ◽  
Extracellular Potassium ◽  
Sodium Influx ◽  
Influx Rate ◽  
High K ◽  
Inner Surface ◽  
Pump Mechanism ◽  
Made In

Measurements were made of the sodium outflux rate constant, okNa, and sodium influx rate constant, ikNa, at varying concentrations of extracellular (Nao) and intracellular (Nac) sodium. okNa increases with increasing [Nao] in the presence of extracellular potassium (Ko) and in solutions containing ouabain. In K-free solutions which do not contain ouabain, okNa falls as [Nao] rises from 0 to 6 mM; above 6 mM, okNa increases with increasing [Nao]. Part of the Na outflux which occurs in solutions free of Na and K disappears when the cells are starved or when the measurements are made in solutions containing ouabain. As [Nao] increases from 0 to 6 mM, ikNa decreases, suggesting that sites involved in the sodium influx are becoming saturated. As [Nac] increases, okNa at first increases and then decreases; this relation between okNa and [Nac] is found when the measurements are made in high Na, high K solutions; high Na, K-free solutions; and in (Na + K)-free solutions. The relation may be the consequence of the requirement that more than one Na ion must react with the transport mechanism at the inner surface of the membrane before transport occurs. Further evidence has been obtained that the ouabain-inhibited Na outflux and Na influx in K-free solutions represent an exchange of Nac for Nao via the Na-K pump mechanism.

scholarly journals Ouabain-Insensitive Sodium Movements in the Human Red Blood Cell

1971 ◽  
Vol 57 (3) ◽  
pp. 259-282 ◽  
Author(s):  
John R. Sachs
Keyword(s):  
Blood Cell ◽  
Red Blood Cells ◽  
Transport System ◽  
Rate Constant ◽  
Red Blood Cell ◽  
Blood Cells ◽  
Electrochemical Gradient ◽  
Sodium Influx ◽  
K Concentration

Red blood cells exposed to ouabain are capable of net Na outflux against an electrochemical gradient; the net outflux is inhibited by the diuretic, furosemide. In ouabain-treated cells, both the unidirectional Na outflux and the unidirectional Na influx are inhibited by furosemide. Furosemide also inhibits the ouabain-sensitive Na-Na exchange accomplished by the Na-K pump in K-free solutions. From the interaction of extracellular K, furosemide, and ouabain with the transport system, it seems possible that the ouabain-insensitive Na outflux is accomplished by the same mechanism that is responsible for the ouabain-sensitive Na-K exchange. The ouabain-insensitive Na outflux is increased by extracellular Na, and the influx increases as the intracellular Na increases. In fresh cells, high extracellular K concentrations decrease the ouabain-insensitive Na outflux and increase the ouabain-insensitive Na influx. When the rate constant for sodium outflux and the rate constant for sodium influx in ouabain-treated cells are plotted against the extracellular K concentration, the curves obtained are mirror images of each other. In starved cells, extracellular K increases the ouabain-insensitive Na outflux as does extracellular Na, and it has little effect on the Na influx.

THE BAND GAP ESTIMATION OF ZINC MANGANESE PHOSPHATE GLASSES

2008 ◽  
Vol 22 (12) ◽  
pp. 1265-1272 ◽  
Author(s):  
S. A. SIDDIQI ◽  
M. A. GHAURI ◽  
M. J. S. BAIG
Keyword(s):  
Electric Fields ◽  
Spectral Dependence ◽  
Transport Mechanism ◽  
Phosphate Glasses ◽  
Band Gaps ◽  
Spectral Energy ◽  
Charge Transport Mechanism ◽  
Optical Band Gaps ◽  
Manganese Phosphate ◽  
Made In

Zinc manganese phosphate glasses ( ZnO - MnO - P 2 O 5) of different compositions are synthesized. The optical band gaps are measured in the UV-VIS region. Photoconduction measurements are also made in the spectral energy range 1.5–6.2 eV. At various applied electric fields, the values of the energy band gaps have been deduced from the spectral dependence curves. Furthermore, the band gaps at zero applied voltage were also obtained for different compositions. The charge transport mechanism in these glasses is studied under the Mott's model.

Evidence that spectrin binds to macromolecular complexes on the inner surface of the red cell membrane

1980 ◽  
Vol 42 (1) ◽  
pp. 1-22 ◽  
Author(s):  
D. Litman ◽  
D.J. Hsu ◽  
V.T. Marchesi
Keyword(s):  
Cell Membrane ◽  
Blood Cell ◽  
Glycophorin A ◽  
Red Cell ◽  
Exposed Surface ◽  
Red Cell Membrane ◽  
Macromolecular Complexes ◽  
High Affinity ◽  
Cytoplasmic Surface ◽  
Inner Surface

Spectrin binds to a population of high-affinity sites on the exposed surface of inverted vesicles prepared from human red blood cell ghost membranes. Optimal spectrin binding requires the presence of monovalent salts but does not require calcium or magnesium. The band 2 subunit of spectrin, prepared in SDS, can also bind to vesicles, but isolated band 1 is inactive. Pre-incubation of inverted vesicles with antibodies directed against the cytoplasmic segment of band 3 or against bands 4.1-4.2 inhibits the binding of spectrin to the same vesicles. Antibodies against the cytoplasmic portion of glycophorin A have no effect. These results suggest that spectrin binds to a protein acceptor on the cytoplasmic surface of the red cell membrane which is close to the cytoplasmic segments of bands 3 and 4.1 and/or 4.2.

A model of Na-K-2Cl cotransport based on ordered ion binding and glide symmetry

1998 ◽  
Vol 274 (2) ◽  
pp. C299-C309 ◽  
Author(s):  
Christian Lytle ◽  
Thomas J. McManus ◽  
Mark Haas
Keyword(s):  
Simple Model ◽  
Blood Cell ◽  
Cation Exchange ◽  
Red Blood Cell ◽  
Ion Binding ◽  
K Cells ◽  
Ion Movement ◽  
High K

In the duck red blood cell, Na-K-2Cl cotransport exhibits two modes of ion movement: net cotransport and obligate cation exchange. In high-K cells, the predominant exchange is K/K (or K/Rb). In high-Na cells, it becomes Na/Na (or Na/Li). Both represent partial reactions in which a fully loaded carrier releases part of its cargo, rebinds fresh ions, and returns back across the membrane fully loaded. Net cotransport occurs when the carrier unloads completely and returns empty. This mode has a fixed stoichiometry of 1Na:1K:2Cl under all conditions tested. The ion requirements of the two exchanges differ: K/K exchange requires only K and Cl outside but all three ions inside. Na/Na exchange requires all three ions outside but only Na inside. We propose a simple model in which the carrier can only move when either fully loaded or completely empty and in which the ions bind in a strictly ordered sequence. For example, externally, a Na binds first and then a Cl, followed by a K and a second Cl. Internally, the first on is the first off (glide symmetry), so the Na is released first and then the first Cl, followed by the K and finally by the second Cl. Only then can the empty form return to the outside to start a new cycle.

Physical characterization of HfO2deposited on Ge substrates by MOCVD.

2004 ◽  
Vol 811 ◽  
Author(s):  
S. Van Elshocht ◽  
B. Brijs ◽  
M. Caymax ◽  
T. Conard ◽  
S. De Gendt ◽  
...  
Keyword(s):  
Physical Properties ◽  
Gate Dielectric ◽  
Substrate Material ◽  
Silicon Substrates ◽  
Enabling Technology ◽  
The Past ◽  
High K ◽  
Alternative Approach ◽  
Made In

ABSTRACTGermanium is because of its intrinsically higher mobility than Si, currently under consideration as an alternative approach to improve transistor performance. Germanium oxide, however, is thermodynamically unstable, preventing formation of the gate dielectric by simple oxidation. At present, high-k dielectrics might be considered as an enabling technology as much progress has been made in the deposition of thin high-quality layers.In this paper, we study the growth and physical properties of HfO2 deposited on Ge by MOCVD, using TDEAH and O2 as precursors, and compare the results to similar layers deposited on silicon substrates. Our results show that the physical properties of MOCVD-deposited HfO2 layers on Ge are very similar to what we have observed in the past for Si. Unfortunately, some of the negative aspects observed for Si, such as diffusion of substrate material in the high-k layer, a low density for thinner layers, or a rough top surface, are also observed for the case of Ge. However, careful surface pretreatments such as NH3 annealing the Ge substrate prior to deposition, can greatly improve the physical properties. An important observation is the very thin interfacial layer between HfO2 and Ge substrate, allowing a more aggressive scaling for Ge.

Effect of adjuvant-induced systemic inflammation in rats on hepatic disposition kinetics of taurocholate

2011 ◽  
Vol 300 (1) ◽  
pp. G130-G136 ◽  
Author(s):  
Michael S. Roberts ◽  
Xin Liu ◽  
Yuhong Zou ◽  
Gerhard A. Siebert ◽  
Ping Chang ◽  
...  
Keyword(s):  
Bile Salt ◽  
Mrna Expression ◽  
Rate Constant ◽  
Systemic Inflammation ◽  
Atp Content ◽  
Influx Rate ◽  
Hepatic Disposition ◽  
Disposition Kinetics ◽  
Bile Salt Transporters ◽  
Kinetics Of

It has been reported that the adjuvant-induced inflammation could affect drug metabolism in liver. Here we further investigated the effect of inflammation on drug transport in liver using taurocholate as a model drug. The hepatic disposition kinetics of [3H]taurocholate in perfused normal and adjuvant-treated rat livers were investigated by the multiple indicator dilution technique and data were analyzed by a previously reported hepatobiliary taurocholate transport model. Real-time RT-PCR was also performed to determine the mRNA expression of liver bile salt transporters in normal and diseased livers. The uptake and biliary excretion of taurocholate were impaired in the adjuvant-treated rats as shown by decreased influx rate constant kin (0.65 ± 0.09 vs. 2.12 ± 0.30) and elimination rate constant kbe (0.09 ± 0.02 vs. 0.17 ± 0.04) compared with control rat group, whereas the efflux rate constant kout was greatly increased (0.07 ± 0.02 vs. 0.02 ± 0.01). The changes of mRNA expression of liver bile salt transporters were found in adjuvant-treated rats. Hepatic taurocholate extraction ratio in adjuvant-treated rats (0.86 ± 0.05, n = 6) was significantly reduced compared with 0.93 ± 0.05 ( n = 6) in normal rats. Hepatic extraction was well correlated with altered hepatic ATP content ( r2 = 0.90). In conclusion, systemic inflammation greatly affects hepatic ATP content/production and associated transporter activities and causes an impairment of transporter-mediated solute trafficking and pharmacokinetics.

scholarly journals QuantitativeIn VitroandIn VivoEvaluation of Intestinal and Blood-Brain Barrier Transport Kinetics of the PlantN-Alkylamide Pellitorine

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Lieselotte Veryser ◽  
Nathalie Bracke ◽  
Evelien Wynendaele ◽  
Tanmayee Joshi ◽  
Pratima Tatke ◽  
...  
Keyword(s):  
Blood Brain Barrier ◽  
Rate Constant ◽  
Cell Monolayer ◽  
Elimination Rate ◽  
Brain Barrier ◽  
Apparent Permeability ◽  
Influx Rate ◽  
Blood Brain ◽  
Apical Side ◽  
The Brain

Objective.To evaluate the gut mucosa and blood-brain barrier (BBB) pharmacokinetic permeability properties of the plantN-alkylamide pellitorine.Methods.Pure pellitorine and anAnacyclus pyrethrumextract were used to investigate the permeation of pellitorine through (1) a Caco-2 cell monolayer, (2) the rat gut after oral administration, and (3) the BBB in mice after intravenous and intracerebroventricular administration. A validated bioanalytical UPLC-MS2method was used to quantify pellitorine.Results.Pellitorine was able to cross the Caco-2 cell monolayer from the apical-to-basolateral and from the basolateral-to-apical side with apparent permeability coefficients between0.6·10-5and4.8·10-5 cm/h and between0.3·10-5and5.8·10-5 cm/h, respectively. In rats, a serum elimination rate constant of 0.3 h−1was obtained. Intravenous injection of pellitorine in mice resulted in a rapid and high permeation of pellitorine through the BBB with a unidirectional influx rate constant of 153 μL/(g·min). In particular, 97% of pellitorine reached the brain tissue, while only 3% remained in the brain capillaries. An efflux transfer constant of 0.05 min−1was obtained.Conclusion.Pellitorine shows a good gut permeation and rapidly permeates the BBB once in the blood, indicating a possible role in the treatment of central nervous system diseases.

IMPROVING THE EFFICIENCY OF THE VORTEX DUST COLLECTORS

2018 ◽  
Vol 8 (3) ◽  
pp. 39-42
Author(s):  
Svetlana M. PURING ◽  
Denis N. VATUZOV
Keyword(s):  
Energy Consumption ◽  
Venturi Tube ◽  
Dust Particles ◽  
Dust Collector ◽  
Effi Ciency ◽  
Inner Surface ◽  
Separation Chamber ◽  
Secondary Air ◽  
Reducing Energy ◽  
Made In

It is proposed to use a modernized “wet” vortex dust collector for cleaning ventilation emissions from non-adhering dust. The design of the vortex dust collector contributes to its effi ciency by installing irrigation nozzles in the primary and secondary air connections made in the form of a Venturi tube, which allows reducing energy consumption during the cleaning of dusty air. Due to the multidirectional movement of dust particles and splashed water, active coagulation of dust particles and water particles occurs, as well as a liquid fi lm is formed on the inner surface of the separation chamber, which prevents the dust particles from rebounding from the separation chamber and facilitates their collection and washing into a collecting bin.

Effect of Extracellular Potassium on the Transport of Sodium and Potassium in Rat Thymocytes

1981 ◽  
Vol 61 (3) ◽  
pp. 307-312 ◽  
Author(s):  
R. B. Jones ◽  
J. Patrick ◽  
P. J. Hilton
Keyword(s):  
Potassium Concentration ◽  
Extracellular Potassium ◽  
Sodium Influx ◽  
Potassium Efflux ◽  
Sodium Efflux ◽  
Extracellular Potassium Concentration ◽  
External Potassium ◽  
Potassium Influx ◽  
Sodium And Potassium

1. The effect of extracellular potassium on the transport of sodium and potassium in rat thymocytes has been studied in vitro. 2. A significant increase in the rate constant for total and ouabain-sensitive sodium efflux was demonstrated at an extracellular potassium concentration of 1 mmol/l as compared with that at either 0 or 2 mmol/l. 3. At potassium concentrations below 3 mmol/l ouabain-sensitive sodium influx was observed suggesting sodium-sodium exchange catalysed by the sodium pump. 4. Both total and ouabain-insensitive potassium efflux rose with external potassium. A small ouabain-sensitive potassium efflux was observed at all levels of external potassium studied. 5. Total and ouabain-insensitive potassium influx increased with external potassium, but did not appear to saturate. Ouabain-sensitive potassium influx reached a maximum at an external potassium concentration of 2 mmol/l then decreased with increasing external potassium.

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