Time resolved kinetics of the guinea pig Na–Ca exchanger (NCX1) expressed in Xenopus oocytes: voltage and Ca2+ dependence of pre-steady-state current investigated by photolytic Ca2+concentration jumps

2007 ◽  
Vol 454 (6) ◽  
pp. 1031-1042 ◽  
Author(s):  
Andreas Haase ◽  
Philip G. Wood ◽  
Verena Pintschovius ◽  
Ernst Bamberg ◽  
Klaus Hartung
Keyword(s):  
Steady State ◽  
Guinea Pig ◽  
Xenopus Oocytes ◽  
Time Resolved ◽  
Steady State Current ◽  
Kinetics Of

Effects of sevoflurane on inward rectifier K+ current in guinea pig ventricular cardiomyocytes

1997 ◽  
Vol 273 (1) ◽  
pp. H324-H332 ◽  
Author(s):  
A. Stadnicka ◽  
Z. J. Bosnjak ◽  
J. P. Kampine ◽  
W. M. Kwok
Keyword(s):  
Steady State ◽  
Guinea Pig ◽  
Outward Current ◽  
Inward Rectifier ◽  
Equilibrium Potential ◽  
Ventricular Cardiomyocytes ◽  
Steady State Current ◽  
Voltage Dependent ◽  
Current Activation ◽  
Extracellular Side

The effects of sevoflurane on the inward rectifier potassium current (IKIR) were examined in guinea pig ventricular cardiomyocytes using the whole cell patch-clamp methodology. Sevoflurane had a unique dual effect on the steady-state current amplitude, producing a reversible, concentration- and voltage-dependent block of the inward current at potentials negative to the potassium equilibrium potential (EK) but enhancing the outward current positive to EK. Accordingly, the steady-state conductance negative to EK was reduced by sevoflurane, but conductance positive to EK was increased. The chord conductance-voltage relationship showed depolarizing shifts at 0.7, 1.3, and 1.6 mM sevoflurane. When the myocytes were dialyzed with 10 mM Mg2+, but not with 1.0 mM Mg2+, sevoflurane further slowed current activation kinetics. With 10 mM intracellular Mg2+, the outward current enhancement by sevoflurane and the associated shifts in half-activation potential were abolished. Polyamines abolished all effects of sevoflurane on IKIR. With the use of the Woodhull model for voltage-dependent block, we determined the sevoflurane interaction site with the inward rectifier potassium channel to be at an electrical distance of 0.2 from the extracellular side.

Improve Persistent Luminescence in Pressure-tuned CsPbBr3 Nanocrystals by Ce3+ Doping

2021 ◽  
Author(s):  
Bao Liu ◽  
Meng Tian ◽  
Yang Gao ◽  
Pengyu Zhou ◽  
Kailin Chi ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Steady State ◽  
Photoluminescence Spectroscopy ◽  
Persistent Luminescence ◽  
Time Resolved ◽  
Novel Strategy ◽  
Time Resolved Photoluminescence ◽  
Kinetics Of

The pressure-dependent photoluminescence kinetics of CsPbBr3:Ce quantum dots was investigated by steady-state and time-resolved photoluminescence spectroscopy. Here, we propose a novel strategy to improve the persistent luminescence of CsPbBr3 quantum...

Substrate interactions in the human type IIa sodium-phosphate cotransporter (NaPi-IIa)

2005 ◽  
Vol 288 (5) ◽  
pp. F969-F981 ◽  
Author(s):  
Leila V. Virkki ◽  
Ian C. Forster ◽  
Jürg Biber ◽  
Heini Murer
Keyword(s):  
Steady State ◽  
Sodium Phosphate ◽  
Complete Removal ◽  
Xenopus Laevis Oocytes ◽  
Charge Movement ◽  
Steady State Current ◽  
Transport Cycle ◽  
Voltage Dependent ◽  
Kinetics Of ◽  
State Charge

We have characterized the kinetics of substrate transport in the renal type IIa human sodium-phosphate cotransporter (NaPi-IIa). The transporter was expressed in Xenopus laevis oocytes, and steady-state and pre-steady-state currents and substrate uptakes were characterized by voltage-clamp and isotope flux. First, by measuring simultaneous uptake of a substrate (32Pi, 22Na) and charge in voltage-clamped oocytes, we established that the human NaPi-IIa isoform operates with a Na:Pi:charge stoichiometry of 3:1:1 and that the preferred transported Pi species is HPO42−. We then probed the complex interrelationship of substrates, pH, and voltage in the NaPi-IIa transport cycle by analyzing both steady-state and pre-steady-state currents. Steady-state current measurements show that the apparent HPO42− affinity is voltage dependent and that this voltage dependency is abrogated by lowering the pH or the Na+ concentration. In contrast, the voltage dependency of the apparent Na+ affinity increased when pH was lowered. Pre-steady-state current analysis shows that Na+ ions bind first and influence the preferred orientation of the transporter in the absence of Pi. Pre-steady-state charge movement was partially suppressed by complete removal of Na+ from the bath, by reducing extracellular pH (both in the presence and absence of Na+), or by adding Pi (in the presence of 100 mM Na). None of these conditions suppressed charge movement completely. The results allowed us to modify previous models for the transport cycle of NaPi-II transporters by including voltage dependency of HPO42− binding and proton modulation of the first Na+ binding step.

Effect of Anodizing Voltage on the Growth Kinetics of Porous Anodic Alumina on Al-0.5 wt% Mn Alloys

2013 ◽  
Vol 795 ◽  
pp. 56-59 ◽  
Author(s):  
C.H. Voon ◽  
Mohd Nazree Derman ◽  
U. Hashim ◽  
K.R. Ahmad
Keyword(s):  
Steady State ◽  
Current Efficiency ◽  
Current Density ◽  
Dielectric Breakdown ◽  
Oxide Growth ◽  
Nucleation Process ◽  
Manganese Alloy ◽  
Steady State Current ◽  
Pore Nucleation ◽  
Kinetics Of

In this study, the effect of anodizing voltage on the current density versus time transient, oxide mass and the current efficiency of anodizing of aluminium manganese alloy was reported. It was found that the anodizing voltage facilitated the pore nucleation process and increased the steady state current density. However, when the anodizing voltage is 70V, dielectric breakdown occurred. The current density versus time transient for anodizing conducted at 30 to 60 V were typical while the shape was unusual for anodizing conducted at 70 V. The rate of oxide growth increased as a function of anodizing voltage. The current efficiency of anodizing increased as the anodizing increased from 30V to 70V.

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