Kinetics of bumetanide-sensitive Na+-K+ co-transport in erythrocytes of essential hypertensive patients

1985 ◽  
Vol 69 (5) ◽  
pp. 607-611 ◽  
Author(s):  
Pietro Delva ◽  
Mario De Gasperi ◽  
Maurizio Degan ◽  
Grazia Covi ◽  
Alessandro Lechi
Keyword(s):  
Kinetic Parameters ◽  
Transport System ◽  
Clinical Data ◽  
Laboratory Data ◽  
Cation Transport ◽  
Hypertensive Patients ◽  
Apparent Affinity ◽  
Normotensive Subjects ◽  
Kinetics Of

1. Outward bumetanide-sensitive Na+-K+ co-transport was studied in the erythrocytes of 51 subjects, 24 normotensive subjects and 27 hypertensive patients, matched for sex and age. 2. Three kinetic parameters of this cation transport system were considered: velocity of efflux at saturating internal sodium (Nai) concentrations (Vmax.), apparent affinity for sodium (K50%) and index of co-operativity among Nai sites (Hill's n). 3. We correlated these values with clinical and laboratory data determined routinely in hypertension. 4. There were no significant differences between normotensive and hypertensive subjects for the values considered and we did not find any significant correlations between co-transport and clinical data.

Na+ leak in erythrocytes from essential hypertensive patients

1985 ◽  
Vol 69 (5) ◽  
pp. 613-624 ◽  
Author(s):  
Ricardo P. Garay ◽  
Corinne Nazaret
Keyword(s):  
Transport System ◽  
Rate Constant ◽  
Kinetic Properties ◽  
Maximal Rate ◽  
Hypertensive Patients ◽  
Apparent Affinity ◽  
Hypertensive Population ◽  
Number Of Patients ◽  
Sucrose Medium ◽  
Na Efflux

1. Ouabain- and bumetanide-resistant (OBR) Na+ efflux from human erythrocytes into a Mg2+-sucrose medium exhibits kinetic properties consistent with a transmembrane Na+ leak. 2. In 52 essential hypertensive patients, the rate constant of Na+ leak (ke) was 15.0 ± 2.9 × 10−3h−1 (mean ±sd). This was significantly higher than the ke in 47 normotensive controls (13.2 ± 1.6 × 10−3h−1; t = 3.81, P < 0.001; Mann-Whitney U rank sum test P = 0.0014). The relatively small number of patients studied was insufficient to decide if the hypertensive population was bi-modally distributed. Nevertheless, if the upper end of the normotensive population is used as a cutoff point, it appears that a subgroup of 12 hypertensive patients had an increased Na+ leak, ke = 19.5 ± 1.9 × 10−3 h−1 (mean±sd). The increased Na+ leak remained constant in repeated determinations over several months. 3. Na+ movements catalysed by the Na+-K+ co-transport and Na+-Li+ countertransport systems were measured in the above 52 hypertensive patients. Seventeen hypertensive patients showed a low apparent affinity of the co-transport system for internal Na+ and 12 exhibited a high maximal rate of Na+-Li+ countertransport. None of these two abnormalities was found in the 12 hypertensive patients with increased ke. We propose to denote them as Leak-(+) hypertensive patients. 4. Passive net Na+ entry was abnormally high in all Leak-(+) hypertensive patients. However, erythrocyte Na+ content was increased in only five of the 12 Leak-(+) hypertensive patients. A normal or even decreased Na+ content was associated with the presence of compensatory increases in the maximal rate of the Na+-K+ pump and the Na+-K+ co-transport system.

scholarly journals Cation transport by the neuronal K+-Cl− cotransporter KCC2: thermodynamics and kinetics of alternate transport modes

2004 ◽  
Vol 287 (4) ◽  
pp. C919-C931 ◽  
Author(s):  
Jeffery R. Williams ◽  
John A. Payne
Keyword(s):  
Cation Transport ◽  
Competitive Inhibitor ◽  
Maximal Velocity ◽  
Apparent Affinity ◽  
Thermodynamics And Kinetics ◽  
Competitive Inhibitors ◽  
Load Cells ◽  
Transport Modes ◽  
Kinetics Of ◽  
Transport Site

Both Cs+ and NH4+ alter neuronal Cl− homeostasis, yet the mechanisms have not been clearly elucidated. We hypothesized that these two cations altered the operation of the neuronal K+-Cl− cotransporter (KCC2). Using exogenously expressed KCC2 protein, we first examined the interaction of cations at the transport site of KCC2 by monitoring furosemide-sensitive 86Rb+ influx as a function of external Rb+ concentration at different fixed external cation concentrations (Na+, Li+, K+, Cs+, and NH4+). Neither Na+ nor Li+ affected furosemide-sensitive 86Rb+ influx, indicating their inability to interact at the cation translocation site of KCC2. As expected for an enzyme that accepts Rb+ and K+ as alternate substrates, K+ was a competitive inhibitor of Rb+ transport by KCC2. Like K+, both Cs+ and NH4+ behaved as competitive inhibitors of Rb+ transport by KCC2, indicating their potential as transport substrates. Using ion chromatography to measure unidirectional Rb+ and Cs+ influxes, we determined that although KCC2 was capable of transporting Cs+, it did so with a lower apparent affinity and maximal velocity compared with Rb+. To assess NH4+ transport by KCC2, we monitored intracellular pH (pHi) with a pH-sensitive fluorescent dye after an NH4+-induced alkaline load. Cells expressing KCC2 protein recovered pHi much more rapidly than untransfected cells, indicating that KCC2 can mediate net NH4+ uptake. Consistent with KCC2-mediated NH4+ transport, pHi recovery in KCC2-expressing cells could be inhibited by furosemide (200 μM) or removal of external [Cl−]. Thermodynamic and kinetic considerations of KCC2 operating in alternate transport modes can explain altered neuronal Cl− homeostasis in the presence of Cs+ and NH4+.

Influence of medium on alkaline hydrolysis of succinic acid monomethyl and monopropyl esters

1980 ◽  
Vol 45 (11) ◽  
pp. 2873-2882
Author(s):  
Vladislav Holba ◽  
Ján Benko
Keyword(s):  
Succinic Acid ◽  
Kinetic Parameters ◽  
Alkaline Hydrolysis ◽  
Specific Interactions ◽  
Nonaqueous Media ◽  
The Media ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of alkaline hydrolysis of succinic acid monomethyl and monopropyl esters were studied in mixed aqueous-nonaqueous media at various temperatures and ionic strengths. The results of measurements are discussed in terms of electrostatic and specific interactions between the reactants and other components of the reaction mixture. The kinetic parameters in the media under study are related to the influence of the cosolvent on the solvation sphere of the reactants.

Kinetics of temperature-programmed reactivation of a hydrodesulphurization catalyst

1983 ◽  
Vol 48 (12) ◽  
pp. 3340-3355 ◽  
Author(s):  
Pavel Fott ◽  
Pavel Šebesta
Keyword(s):  
Carbon Dioxide ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Thin Layer ◽  
Kinetic Parameters ◽  
Diffusion Region ◽  
Reaction Heat ◽  
Gaseous Products ◽  
Temperature Programmed ◽  
Kinetics Of

The kinetic parameters of reactivation of a carbonized hydrodesulphurization (HDS) catalyst by air were evaluated from combined thermogravimetric (TG) and differential thermal analysis (DTA) data. In addition, the gaseous products leaving a temperature-programmed reactor with a thin layer of catalyst were analyzed chromatographically. Two exothermic processes were found to take part in the reactivation, and their kinetics were described by 1st order equations. In the first process (180-400 °C), sulphur in Co and Mo sulphides is oxidized to sulphur dioxide; in the second process (300-540 °C), in which the essential portion of heat is produced, the deposited carbon is oxidized to give predominantly carbon dioxide. If the reaction heat is not removed efficiently enough, ignition of the catalyst takes place, which is associated with a transition to the diffusion region. The application of the obtained kinetic parameters to modelling a temperature-programmed reactivation is illustrated on the case of a single particle.

Kinetics of bioactive compounds in functional spice Jiangpo during thermal processing

2012 ◽  
Vol 8 (3) ◽  
Author(s):  
Xiaoyan Dai ◽  
Chenhuan Yu ◽  
Qiaofeng Wu
Keyword(s):  
Kinetic Parameters ◽  
Bioactive Compounds ◽  
Thermal Processing ◽  
Order Rate Constant ◽  
Heat Processing ◽  
Order Kinetic ◽  
Time Intervals ◽  
First Order ◽  
Order Kinetic Model ◽  
Kinetics Of

Abstract Jiangpo is an increasingly popular East Asian spice which is made from Mangnolia officinalis bark and ginger juice. Since it induces bioactive compounds decomposition and has influence on final flavor and fragrance, cooking is regarded as the key operation in preparation of Jiangpo. To evaluate the bioactive compounds content changes of Jiangpo during thermal processing, kinetic parameters including reaction order, rate constant, T1/2 and activation energy of bioactive markers namely honokiol, magnolol and curcumin were determined. Cooking was set at temperatures 60, 90 and 120 °C for selected time intervals. Results displayed the thermal kinetic characteristics of the three compounds. Thermal degradation of Honokiol and magnolol both followed first order kinetic model and the loss of curcumin fitted second order. A mathematical model based on the obtained kinetic parameters has also been developed to predict the degradation of honokiol, magnolol and curcumin in non-isothermal state. All the information in this paper could contribute necessary information for optimizing the existing heat processing of Jiangpo.

Oxygen Absorption Kinetics of Sheets and Films Containing a Commercial Iron-based Oxygen Scavenger

2009 ◽  
Vol 15 (2) ◽  
pp. 159-168 ◽  
Author(s):  
M.J. Galotto ◽  
S.A. Anfossi ◽  
A. Guarda
Keyword(s):  
Relative Humidity ◽  
Kinetic Parameters ◽  
Oxygen Absorption ◽  
Absorption Kinetics ◽  
Oxygen Scavenger ◽  
Arrhenius Behavior ◽  
Oxygen Scavengers ◽  
Iron Based ◽  
Empirical Growth ◽  
Kinetics Of

Absorption kinetics of three different forms of the same iron-based oxygen scavenger were studied. Oxygen scavengers were used as pellet, sheet, and film materials. Two scavenger concentrations were used for sheet and film forms. Scavenger samples were analyzed at 75 or 100% relative humidities and stored at 5, 15, and 25°C. Oxygen concentration in the headspace was measured as a function of time. Absorption kinetics was best described by the Chapman-Richards empirical growth model rather than by a first-order reaction. Arrhenius behavior was observed for variations in the final absorption rate with temperature. Absorption capacities, final absorption rates, and activation energies were evaluated and discussed. Scavenger concentration, relative humidity, and temperature effects on kinetic parameters were studied for each experimental condition. Temperature was the most important factor that affected kinetic parameters. At the relative humidity levels studied, any important effect on kinetic parameters was not observed, except on absorption capacities.

Abstract P274: Fruit Extract (blueberry, Cranberry, And Promegranate) Improved Insulin Resistance In Overweight Hypertensive And Normotensive Subjects

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Ludmila N Novaes ◽  
Mariele Moraes ◽  
Keyla Katayama ◽  
Carine Sangaleti ◽  
Maria Claudia Irigoyen ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Lipid Metabolism ◽  
Repeated Measures ◽  
Hdl Cholesterol ◽  
Biochemical Tests ◽  
Fruit Extract ◽  
Hypertensive Patients ◽  
Glucose And Lipid Metabolism ◽  
Normotensive Subjects ◽  
Group B

Arterial hypertension is frequently associated to glucose and lipid metabolism abnormalities. The purpose of this study was to determine if antioxidants (fruit extract) supplementation interfere with glucose and lipid metabolism in overweight hypertensive patients. A randomized clinical trial was conducted with 30 individuals, 23 hypertensive patients (group A) and 7 normotensive controls (group B). They were randomized to take 3 capsules of different fruits extract a day (blueberry, cranberry and pomegranate) or placebo for 4 weeks. This is a crossover study, which started with placebo changed to capsules and vice versa. Blood samples were collected after 12 hours fasting for biochemical tests (glucose, insulin, total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides), anthropometric assessment (weight, height, and body mass index), systolic BP, diastolic BP and heart rate were evaluated at baseline, after 4, and 8 weeks. The comparisons between groups were held with the GLM repeated measures. Twenty three hypertensive patients (age 47 years, 14 females) and 7 normotensive controls (age 40 years, 7 females) were evaluated. BMI, blood pressure, heart and lipid profile did not differ between groups. HOMAir decreased significantly in both groups. See results in table 1. Values are expressed as medians (±SD) In these preliminary results a 4-weeks supplementation of antioxidants (fruit extract) improved insulin resistance in overweight hypertensive and normotensive subjects. Financial support: FAPESP 2014/25808-3

scholarly journals The kinetics of the hydrogen chloride oxidation

2013 ◽  
Vol 78 (12) ◽  
pp. 2115-2130 ◽  
Author(s):  
Martinez Gonzalez ◽  
Tanja Vidakovic-Koch ◽  
Rafael Kuwertz ◽  
Ulrich Kunz ◽  
Thomas Turek ◽  
...  
Keyword(s):  
Kinetic Parameters ◽  
Gas Phase ◽  
Hydrogen Chloride ◽  
Reaction Order ◽  
Membrane Electrode ◽  
Polarization Data ◽  
Rate Determining Step ◽  
Electrode Assemblies ◽  
Apparent Kinetic Parameters ◽  
Kinetics Of

Hydrogen chloride (HCl) oxidation has been investigated on technical membrane electrode assemblies in a cyclone flow cell. Influence of Nafion loading, temperature and hydrogen chloride mole fraction in the gas phase has been studied. The apparent kinetic parameters like reaction order with respect to HCl, Tafel slope and activation energy have been determined from polarization data. The apparent kinetic parameters suggest that the recombination of adsorbed Cl intermediate is the rate determining step.

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