Effects of the membrane potential on the kinetics of carrier mediated Ion translocation

1980 ◽  
Vol 6 (S1) ◽  
pp. 64-64 ◽  
Author(s):  
P. W. J. A. Barts ◽  
G. W. F. H. Borst Pauwels
Keyword(s):  
Membrane Potential ◽  
Ion Translocation ◽  
Kinetics Of

scholarly journals Fusicoccin (FC)-Induced Rapid Growth, Proton Extrusion and Membrane Potential Changes in Maize (Zea mays L.) Coleoptile Cells: Comparison to Auxin Responses

2021 ◽  
Vol 22 (9) ◽  
pp. 5017
Author(s):  
Małgorzata Polak ◽  
Waldemar Karcz
Keyword(s):  
Membrane Potential ◽  
Rapid Growth ◽  
Proton Pumps ◽  
Proton Extrusion ◽  
Membrane Hyperpolarization ◽  
Fungal Toxin ◽  
Maize Coleoptile ◽  
Lag Times ◽  
Kinetics Of ◽  
Indole 3 Acetic Acid

The fungal toxin fusicoccin (FC) induces rapid cell elongation, proton extrusion and plasma membrane hyperpolarization in maize coleoptile cells. Here, these three parameters were simultaneously measured using non-abraded and non-peeled segments with the incubation medium having access to their lumen. The dose–response curve for the FC-induced growth was sigmoidal shaped with the maximum at 10−6 M over 10 h. The amplitudes of the rapid growth and proton extrusion were significantly higher for FC than those for indole-3-acetic acid (IAA). The differences between the membrane potential changes that were observed in the presence of FC and IAA relate to the permanent membrane hyperpolarization for FC and transient hyperpolarization for IAA. It was also found that the lag times of the rapid growth, proton extrusion and membrane hyperpolarization were shorter for FC compared to IAA. At 30 °C, the biphasic kinetics of the IAA-induced growth rate could be changed into a monophasic (parabolic) one, which is characteristic for FC-induced rapid growth. It has been suggested that the rates of the initial phase of the FC- and IAA-induced growth involve two common mechanisms that consist of the proton pumps and potassium channels whose contribution to the action of both effectors on the rapid growth is different.

scholarly journals The Role of Na,k-Atpase α Subunit Serine 775 and Glutamate 779 in Determining the Extracellular K+And Membrane Potential–Dependent Properties of the Na,k -Pump

2000 ◽  
Vol 116 (1) ◽  
pp. 47-60 ◽  
Author(s):  
R. Daniel Peluffo ◽  
José M. Argüello ◽  
Joshua R. Berlin
Keyword(s):  
Membrane Potential ◽  
Voltage Dependence ◽  
Protein Structures ◽  
Pump Current ◽  
Transmembrane Segment ◽  
Α Subunit ◽  
Voltage Dependent ◽  
Kinetics Of ◽  
Α1 Subunit

The roles of Ser775 and Glu779, two amino acids in the putative fifth transmembrane segment of the Na,K -ATPase α subunit, in determining the voltage and extracellular K + (K +o) dependence of enzyme-mediated ion transport, were examined in this study. HeLa cells expressing the α1 subunit of sheep Na,K -ATPase were voltage clamped via patch electrodes containing solutions with 115 mM Na+ (37°C). Na,K -pump current produced by the ouabain-resistant control enzyme (RD), containing amino acid substitutions Gln111Arg and Asn122Asp, displayed a membrane potential and K +o dependence similar to wild-type Na,K -ATPase during superfusion with 0 and 148 mM Na+-containing salt solutions. Additional substitution of alanine at Ser775 or Glu779 produced 155- and 15-fold increases, respectively, in the K +o concentration that half-maximally activated Na,K -pump current at 0 mV in extracellular Na+-free solutions. However, the voltage dependence of Na,K -pump current was unchanged in RD and alanine-substituted enzymes. Thus, large changes in apparent K +o affinity could be produced by mutations in the fifth transmembrane segment of the Na,K -ATPase with little effect on voltage-dependent properties of K + transport. One interpretation of these results is that protein structures responsible for the kinetics of K +o binding and/or occlusion may be distinct, at least in part, from those that are responsible for the voltage dependence of K +o binding to the Na,K -ATPase.

scholarly journals Second-Harmonic Generation Imaging of Membrane Potential with Photon Counting

2008 ◽  
Vol 14 (6) ◽  
pp. 526-531 ◽  
Author(s):  
Jiang Jiang ◽  
Rafael Yuste
Keyword(s):  
Membrane Potential ◽  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Photon Counting ◽  
Analog Voltage ◽  
Second Harmonic Generation Imaging ◽  
Kinetics Of ◽  
Small Voltage ◽  
Pulse Variation

AbstractSecond-harmonic generation (SHG) can be used for imaging membrane potential in neurons, but poor signal-to-noise (S/N) limits accurate measurements of small voltage transients. We use photon counting to improve the S/N of weak SHG signal detection. Photon counting generates shot-noise limited and integrable signals, eliminates pulse-to-pulse variation, and built-in discriminators reduces the background to practically zero. In single trials, by using photon counting, we obtain a more than a twofold S/N increase over analog voltage detection. Trial-to-trial variability is also reduced by 50%. Finally, we show that, using photon counting, the kinetics of fast events such as action potentials can be recorded more accurately.

scholarly journals Dilation of the influenza hemagglutinin fusion pore revealed by the kinetics of individual cell-cell fusion events.

1996 ◽  
Vol 135 (1) ◽  
pp. 63-71 ◽  
Author(s):  
R Blumenthal ◽  
D P Sarkar ◽  
S Durell ◽  
D E Howard ◽  
S J Morris
Keyword(s):  
Membrane Potential ◽  
Cell Fusion ◽  
Individual Cell ◽  
Fluorescent Dye ◽  
Fusion Pore ◽  
Influenza Hemagglutinin ◽  
Rbc Membrane ◽  
Pore Opening ◽  
Kinetics Of ◽  
Fluorescent Lipid

We have monitored kinetics of fusion between cell pairs consisting of a single influenza hemaglutinin (HA)-expressing cell and a single erythrocyte (RBC) that had been labeled with both a fluorescent lipid (Dil) in the membrane and a fluorescent solute (calcein) in the aqueous space. Initial fusion pore opening between the RBC and HA-expressing cell produced a change in RBC membrane potential (delta psi) that was monitored by a decrease in Dil fluorescence. This event was followed by two distinct stages of fusion pore dilation: the flux of fluorescent lipid (phi L) and the flux of a large aqueous fluorescent dye (phi s). We have analyzed the kinetics of events that occur as a result of transitions between a fusion pore (FP) and a solute permissive fusion pore (FPs). Our data are consistent with a fusion pore comprising six HA trimers.

Energy-dependent H+ and K+ translocation by the reconstituted yeast plasma membrane ATPase

1984 ◽  
Vol 62 (9) ◽  
pp. 865-877 ◽  
Author(s):  
Antonio Villalobo
Keyword(s):  
Plasma Membrane ◽  
Membrane Potential ◽  
Atp Hydrolysis ◽  
Potassium Ion ◽  
Plasma Membrane Atpase ◽  
Atpase Inhibitor ◽  
Yeast Plasma Membrane ◽  
Ion Translocation ◽  
Membrane Atpase ◽  
Energy Dependent

A highly purified plasma membrane ATPase from the yeast Schizosaccharomyces pombe incorporated into liposomes was able to carry out translocation of H+ and K+ in the absence of the substrate ATP, when a membrane potential of appropriate polarity was applied. In the absence of ATP, the membrane potential induced K+ translocation was strongly inhibited by the ATPase inhibitor vanadate. [Formula: see text], but not [Formula: see text], stimulated the rate of ATP hydrolysis in the absence, but not in the presence, of the H+-conducting agent carbonylcyanide m-chlorophenylhydrazone. Sodium ion on either side of the membrane did not have any stimulatory effect. The potassium ion translocation driven by ATP hydrolysis appeared to have two different kinetic components. Although the ATP-dependent K+ transport strictly required the presence of a membrane potential, the rate of K+ translocation was not affected by a broad modulation of the degree of coupling (q) between ATP hydrolysis and the electrogenic H+ translocation. These experiments support the view that the yeast plasma membrane ATPase not only uses the membrane potential generated by the electrogenic H+ translocation, but also uses part of the free energy of the hydrolysis of ATP (ΔGP) to translocate potassium ion across the cytoplasmic cell membrane.

scholarly journals Modulation of electrical activity and ionic currents of isolated neurons by orexin A

2013 ◽  
Vol 11 (4) ◽  
pp. 54-60
Author(s):  
Petr Dmitriyevich Shabanov ◽  
Anatoliy Ivanovich Vislobokov
Keyword(s):  
Membrane Potential ◽  
Lymnaea Stagnalis ◽  
Ionic Currents ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Isolated Neurons ◽  
Orexin A ◽  
High Concentrations ◽  
Kinetics Of ◽  
Dose Dependent

The changes in intracellular potential of resting (PR) and potential of action (PA) of the identified neurons of pedal and visceral ganglia of the CNS mollusk Planorbarius corneus registered by means of intracellular electrodes, and ionic currents of isolated neurons under fixed potential after administration of orexin A in concentrations 1, 10, 100 and 1000 µg/ml were studied by the method of fixation of membrane potential in isolated neurons of the Lymnaea stagnalis mollusk. Dibazol in concentrations of 1 and 10 µM effected slightly on the ionic currents. High concentrations of dibazol (100 and 1000 µM) inhibited all currents in dose dependent manner with maximal effect on potassium currents amplitude. ЕС50 were 7.4 мМ for INa, 4.0 мМ for ICa, 83.9 µM for IKs,1 (one group of neurons) and 2.9 мМ for IKs,2 (the another group of neurons). The voltage-amper membrane characteristics shift was not registered, but the kinetics of currents development was changed. Dibazol was more effective in inhibition of ionic currents compared to its structural analogs.

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