Effect of the non-linear membrane potential on the migration of ionic species in concrete

2009 ◽  
Vol 54 (10) ◽  
pp. 2761-2769 ◽  
Author(s):  
Juan Lizarazo Marriaga ◽  
Peter Claisse
Keyword(s):  
Membrane Potential ◽  
Ionic Species ◽  
Non Linear

Transient peak membrane potential in a liquid membrane system generated by pH jump: Non-linear response to perturbation

1987 ◽  
Vol 17 (2) ◽  
pp. 193-203 ◽  
Author(s):  
Kazuo Nomura ◽  
Shao-Mu Ma ◽  
Hiroshi Kamaya ◽  
Issaku Ueda ◽  
Sheng H. Lin
Keyword(s):  
Membrane Potential ◽  
Linear Response ◽  
Liquid Membrane ◽  
Membrane System ◽  
Non Linear ◽  
Ph Jump

The Neuron at Rest

2017 ◽  
Author(s):  
Peggy Mason
Keyword(s):  
Membrane Potential ◽  
Ion Channels ◽  
Ionic Species ◽  
Membrane Resistance ◽  
Chloride Ions ◽  
Resting Membrane Potential ◽  
Neuronal Membrane ◽  
Nernst Potential ◽  
State Potential ◽  
Pass Through

Neuronal membrane potential depends on the distribution of ions across the plasma membrane and the permeability of the membrane to those ions afforded by transmembrane proteins. Ions cannot pass through a lipid bilayer but enter or exit neurons through ion channels. When activated by voltage or a ligand, ion channels open to form a pore through which selective ions can pass. The ion channels that support a resting membrane potential are critical to setting a cell’s excitability. From the distribution of an ionic species, the Nernst potential can be used to predict the steady-state potential for that one ion. Neurons are permeable to potassium, sodium, and chloride ions at rest. The Goldman-Hodgkin-Katz equation takes into consideration the influence of multiple ionic species and can be used to predict neuronal membrane potential. Finally, how synaptic inputs affect neurons through synaptic currents and changes in membrane resistance is described.

Synthesis and non-linear optical properties of new ionic species: tolan and diphenylbutadiyne with trimethylammonio and dimethylamino groups

2005 ◽  
Vol 18 (5) ◽  
pp. 468-472 ◽  
Author(s):  
Hirohito Umezawa ◽  
Shuji Okada ◽  
Hidetoshi Oikawa ◽  
Hiro Matsuda ◽  
Hachiro Nakanishi
Keyword(s):  
Optical Properties ◽  
Ionic Species ◽  
Non Linear ◽  
Linear Optical Properties ◽  
Linear Optical

scholarly journals Mechanism of Copper Surface Toxicity in Vancomycin-Resistant Enterococci following Wet or Dry Surface Contact

2011 ◽  
Vol 77 (17) ◽  
pp. 6049-6059 ◽  
Author(s):  
S. L. Warnes ◽  
C. W. Keevil
Keyword(s):  
Cell Death ◽  
Membrane Potential ◽  
Copper Alloys ◽  
Copper Ion ◽  
Ionic Species ◽  
Copper Surface ◽  
Surface Cleaning ◽  
Ion Release ◽  
Content Type ◽  
Surface Contact

ABSTRACTContaminated touch surfaces have been implicated in the spread of hospital-acquired infections, and the use of biocidal surfaces could help to reduce this cross-contamination. In a previous study we reported the death of aqueous inocula of pathogenicEnterococcus faecalisorEnterococcus faeciumisolates, simulating fomite surface contamination, in 1 h on copper alloys, compared to survival for months on stainless steel. In our current study we observed an even faster kill of over a 6-log reduction of viable enterococci in less than 10 min on copper alloys with a “dry” inoculum equivalent to touch contamination. We investigated the effect of copper(I) and copper(II) chelation and the quenching of reactive oxygen species on cell viability assessed by culture and their effects on genomic DNA, membrane potential, and respirationin situon metal surfaces. We propose that copper surface toxicity for enterococci involves the direct or indirect action of released copper ionic species and the generation of superoxide, resulting in arrested respiration and DNA breakdown as the first stages of cell death. The generation of hydroxyl radicals by the Fenton reaction does not appear to be the dominant instrument of DNA damage. The bacterial membrane potential is unaffected in the early stages of wet and dry surface contact, suggesting that the membrane is not compromised until after cell death. These results also highlight the importance of correct surface cleaning protocols to perpetuate copper ion release and prevent the chelation of ions by contaminants, which could reduce the efficacy of the surface.

Modeling and simulation of transmembrane ionic transport of cells exposed to magnetic field using the Monte Carlo method

2020 ◽  
pp. 1-12
Author(s):  
M.C. Barrero-Moreno ◽  
E. Restrepo-Parra ◽  
J. Torres-Osorio
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
Membrane Potential ◽  
Monte Carlo Method ◽  
Magnetic Field Gradient ◽  
Ionic Current ◽  
Ionic Transport ◽  
Ionic Species ◽  
Extracellular Medium ◽  
The Monte Carlo Method

This work presents a model for the simulation of plasmatic transmembrane ionic transport that may be exposed to a static gradient magnetic field. The simulation was carried out using the Monte Carlo method to simulate the transmembrane cell transport of five types of ions and obtain observables such as membrane potential, ionic current, and osmotic pressure. To implement the Monte Carlo method, a Hamiltonian was used that includes the contributions of the energy due to the cellular electric field, the electrostatic interaction between the ions, the friction force generated by moving the ion in the center and the contribution given by subduing a cell to a magnetic field gradient. The input parameters to carry out a simulation are the intra and extracellular concentrations of each ionic species, the length of the extracellular medium, the number of Monte Carlo steps (MCS) and the value of the magnetic gradient. The model was validated contrasting it with Gillespie’s algorithm to obtain variations less than 3 % in terms of membrane potential. The Monte Carlo Method combined with the Metropolis algorithm were considered for recreating the stochastic behavior of ion movement.

scholarly journals Positively selected modifications in the pore of TbAQP2 allow pentamidine to enter Trypanosoma brucei

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Ali H Alghamdi ◽  
Jane C Munday ◽  
Gustavo Daniel Campagnaro ◽  
Dominik Gurvic ◽  
Fredrik Svensson ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Amino Acids ◽  
Membrane Potential ◽  
Gene Family ◽  
Pore Size ◽  
Trypanosoma Brucei ◽  
Common Ancestor ◽  
Ionic Species ◽  
Cross Resistance ◽  
Structural Determinants

Mutations in the Trypanosoma brucei aquaporin AQP2 are associated with resistance to pentamidine and melarsoprol. We show that TbAQP2 but not TbAQP3 was positively selected for increased pore size from a common ancestor aquaporin. We demonstrate that TbAQP2’s unique architecture permits pentamidine permeation through its central pore and show how specific mutations in highly conserved motifs affect drug permeation. Introduction of key TbAQP2 amino acids into TbAQP3 renders the latter permeable to pentamidine. Molecular dynamics demonstrates that permeation by dicationic pentamidine is energetically favourable in TbAQP2, driven by the membrane potential, although aquaporins are normally strictly impermeable for ionic species. We also identify the structural determinants that make pentamidine a permeant although most other diamidine drugs are excluded. Our results have wide-ranging implications for optimising antitrypanosomal drugs and averting cross-resistance. Moreover, these new insights in aquaporin permeation may allow the pharmacological exploitation of other members of this ubiquitous gene family.

scholarly journals Electrical Propagation of Condensed and Diffuse Ions Along Actin Filaments

2021 ◽  
Author(s):  
Christian Hunley ◽  
Marcelo Marucho
Keyword(s):  
Physicochemical Properties ◽  
Actin Filaments ◽  
Electric Circuit ◽  
Ionic Species ◽  
Propagation Mechanism ◽  
Electrical Transmission ◽  
Condensed Layer ◽  
Non Linear ◽  
Ionic Calcium ◽  
Diffuse Layers

In this article, we elucidate the role of divalent ion condensation and high polarization of immobile water molecules in the condensed layer on the propagation of ionic calcium waves along actin filaments. We introduced a novel electrical triple layer model and used a non-linear Debye-Huckel theory with a non-linear, dissipative, electrical transmission line model to characterize the physicochemical properties of each monomer in the filament. This characterization is carried out in terms of an electric circuit model containing monomeric flow resistances and ionic capacitances in both the condensed and diffuse layers. In our studies, we characterized the biocylindrical actin filament model using a high resolution molecular structure. We considered resting and excited states of a neuron using representative mono and divalent electrolyte mixtures. Additionally, we used 0.05V and 0.15V voltage inputs to study ionic waves in voltage clamp experiments on actin filaments. Our results reveal that the physicochemical properties characterizing the condensed and diffuse layers lead to different electrical conduction mediums depending on the ionic species and the neuron state. This region specific propagation mechanism provides a more realistic avenue of delivery by way of cytoskeleton filaments for larger charged cationic species. This new direct path for transporting divalent ions might be crucial for many electrical processes that connect different compartments of the neuron to the soma.

scholarly journals Positively selected modifications in the pore of TbAQP2 allow pentamidine to enter Trypanosoma brucei

2020 ◽  
Author(s):  
Ali H. Alghamdi ◽  
Jane C. Munday ◽  
Gustavo D. Campagnaro ◽  
Dominik Gurvič ◽  
Fredrik Svensson ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Amino Acids ◽  
Membrane Potential ◽  
Gene Family ◽  
Pore Size ◽  
Trypanosoma Brucei ◽  
Common Ancestor ◽  
Ionic Species ◽  
Cross Resistance ◽  
Structural Determinants

AbstractMutations in the Trypanosoma brucei aquaporin AQP2 are associated with resistance to pentamidine and melarsoprol. We show that TbAQP2 but not TbAQP3 was positively selected for increased pore size from a common ancestor aquaporin. We demonstrate that TbAQP2’s unique architecture permits pentamidine permeation through its central pore and show how specific mutations in highly conserved motifs affect drug permeation. Introduction of key TbAQP2 amino acids into TbAQP3 renders the latter permeable to pentamidine. Molecular dynamics demonstrates that permeation by dicationic pentamidine is energetically favourable in TbAQP2, driven by the membrane potential, although aquaporins are normally strictly impermeable for ionic species. We also identify the structural determinants that make pentamidine a permeant but exclude most other diamidine drugs. Our results have wide-ranging implications for optimising antitrypanosomal drugs and averting cross-resistance. Moreover, these new insights in aquaporin permeation may allow the pharmacological exploitation of other members of this ubiquitous gene family.

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