Factbites
 Where results make sense
About us   |   Why use us?   |   Reviews   |   PR   |   Contact us  

Topic: Transmembrane potential


Related Topics
Ion

In the News (Mon 17 Jun 19)

  
  Neuroscience for Kids - Action Potential
The resting membrane potential of a neuron is about -70 mV (mV=millivolt) - this means that the inside of the neuron is 70 mV less than the outside.
Also, when the threshold level is reached, an action potential of a fixed sized will always fire...for any given neuron, the size of the action potential is always the same.
Action potentials are caused by an exchange of ions across the neuron membrane.
faculty.washington.edu /chudler/ap.html   (767 words)

  
 Action potential - Open Encyclopedia   (Site not responding. Last check: 2007-10-22)
The transmembrane voltage changes that take place during an action potential result from changes in the permeability of the membrane to specific ions, the internal and external concentrations of which cells maintain in an imbalance.
In his discovery of "animal electricity," Luigi Galvani elicited an action potential through contact of his scalpel with the sciatic motor nerve of a frog he was dissecting, causing one of its legs to kick as in life.
In an unmyelinated axon that is firing an action potential, the transmembrane potential at any instant will vary from point to point along the fiber, with its amplitude depending on whether the AP wave has reached that point or passed it, and how long ago.
open-encyclopedia.com /Action_potential   (1147 words)

  
 Cell potential
This voltage is the resting cell potential, also sometimes called the transmembrane potential of the resting cell.
The transmembrane potenial of the mitochondria drives the prodution of ATP, which is the common currency of biological energy.
These changes in the membrane potential itself can enable communication with other cells--as in the case of the impulses that travel nerves--or initiate changes inside the cell that undergoes them--such as the changes in an egg when it is fertilized by a sperm.
www.brainyencyclopedia.com /encyclopedia/c/ce/cell_potential.html   (504 words)

  
 Transmembrane potential changes caused by monophasic and biphasic shocks -- Zhou et al. 275 (5): 1798 -- AJP - Heart ...
Transmembrane potential recordings during shocks of 6.4 V/cm given at different phases of action potential from same impalement.
The 9th control action potential (dashed line) is superimposed on the 10th test action potential for the 10-ms monophasic shock given with a 30-ms S1-S2 coupling interval.
Responses of the transmembrane potential of myocardial cells during a shock.
ajpheart.physiology.org /cgi/content/full/275/5/H1798   (6001 words)

  
 Old Meetings: BIOTRANSPORT98   (Site not responding. Last check: 2007-10-22)
The transmembrane potential threshold for electroporation that we observed is lower than those reported for other types of membranes.
In studies that used external electrodes to apply an electric field, transmembrane potential was estimated from analytical expressions.16 The actual membrane potential may differ considerably from theoretical estimates and may be spatially non-uniform.
An increase in transmembrane potential favors both creation and expansion of pores causing an increase in the fraction of membrane area occupied by pores and consequently the membrane conductance, because higher transmembrane potentials overwhelm diffusion-limited process of pore contraction.
www.ichmt.org /abstracts/BIOTRANSPORT-98/session9.html   (3973 words)

  
 biology - Action potential   (Site not responding. Last check: 2007-10-22)
While the cell is at resting cell potential the electric forces between the sodium and potassium of the neuron is counterbalanced by the "diffusive forces," creating a state of equilibrium.
Action potential initiation occurs at a region called the axon hillock, a point near the base of the axon with the highest concentration of voltage gated ion channels but may occur anywhere along the axon.
Where membrane has undergone an action potential a refractory period follows, during which a second action potential is inhibited due to the reversible inactivation of ion channels.
www.biologydaily.com /biology/Action_potential   (1217 words)

  
 Action potential   (Site not responding. Last check: 2007-10-22)
The transmembrane voltage changes that take place during an action potential result from changes in the permeability of the cell membranemembrane to specific ions, the internal and external concentrations of which cells maintain in an imbalance.
While the cell is at resting cell potential the electric forces between the sodium and potassium of the neuron is counterbalanced by the "entropydiffusive forces/," creating a state of equilibrium.
In his discovery of "animal electricity," Luigi Galvani elicited an action potential through contact of his scalpel with the sciatic nervesciatic/ motor nerve of a frog he was dissecting, causing one of its legs to kick as in life.
www.infothis.com /find/Action_potential   (1515 words)

  
 ANATOMY & PHYSIOLOGY I
The resting potential is the transmembrane potential of an undisturbed cell.
The resting potential remains stable because when the transmembrane potential is at that level the sodium/potassium exchange pumps can keep pace with the rates of sodium entry andpotassium loss.
Graded changes in the transmembrane potential are local events, and only affect the regions in contact with the stimulus.
rmoskowitz.tripod.com /muscle.html   (1848 words)

  
 Activation of Phospholipase C Increases Intramembrane Electric Fields in N1E-115 Neuroblastoma Cells -- Xu and Loew 84 ...
depolarization of the membrane potential of 7.2 ± 0.9
Membrane potential was recorded by whole-cell current clamp, and membrane resistance was monitored by the voltage response to brief hyperpolarizing current injections (0.15 nA).
that the increase in intramembrane potential is the underlying
www.biophysj.org /cgi/content/full/84/6/4144   (6799 words)

  
 Transmembrane potential difference Details, Meaning Transmembrane potential difference Article and Explanation Guide
Transmembrane potential difference is the electrical potential difference across a plasma membrane.
A graded potential is a gradient of transmembrane potential difference.
The membrane potential also tends to keep anions like Cl- out of the cell because their charge is also negative.
www.e-paranoids.com /t/tr/transmembrane_potential_difference.html   (454 words)

  
 Nonuniform responses of transmembrane potential during electric field stimulation of single cardiac cells -- Cheng et ...
Transmembrane potential at end of cell could be recorded during field stimulation by acquiring the fluorescent signal at this spot with photodiode.
A: optical transmembrane potentials were measured at the same end of a single guinea pig ventricular cell before and after reversal of S1 and S2 field directions.
Post-shock potential gradients and dispersion of repolarization in cells stimulated with monophasic and biphasic waveforms.
ajpheart.physiology.org /cgi/content/full/277/1/H351   (7255 words)

  
 Human epidermal cells progressively lose their cardiolipins during ageing without change in mitochondrial transmembrane ...
For this reason, cardiolipin, a suitable marker of the chondriome, as well as the mitochondrial transmembrane potential were examined in keratinocytes obtained from 9- to 75-year-old women.
The stability of the membrane potential may be explained by either or both of the following hypotheses: (i) the same pool of organelles able to maintain membrane potential is conserved even when cardiolipin levels decrease (ii) mitochondria membrane potential does indeed decrease with age but is compensated by glycolysis energy production.
Finally, it may be stated that the fluorescent probes nonyl acridine orange and rhodamine 123 might be of interest in testing the phenotype of senescent cells and would be useful in screening the role of certain specific genes in cell ageing.
www.arclab.org /medlineupdates/abstract_7745994.html   (261 words)

  
 NO/cGMP Pathway Activation and Membrane Potential Depolarization in Pig Ciliary Epithelium -- Fleischhauer et al. 41 ...
A significant depolarization of the ciliary epithelium baseline transmembrane
Original recording of the transmembrane potential obtained after penetration of the epithelium of an isolated porcine ciliary process with a microelectrode.
induces a membrane potential depolarization of the ciliary epithelium
www.iovs.org /cgi/content/full/41/7/1759   (2781 words)

  
 Detection of a Membrane Shunt by DC Field Polarization During Intracellular and Whole Cell Recording -- Svirskis et al. ...
The shunt is supposed to be ohmic (Holmes and Rall
A sample distribution of the transmembrane potential is presented in Fig.
-mediated plateau potentials in a subpopulation of interneurons in the ventral horn of the turtle spinal cord.
jn.physiology.org /cgi/content/full/77/2/579   (4723 words)

  
 Effects of electroporation on optically recorded transmembrane potential responses to high-intensity electrical shocks ...
Elevation of the diastolic potential and saturation of
Nonuniform responses of transmembrane potential during electric field stimulation of single cardiac cells.
Transmembrane voltage changes produced by real and virtual electrodes during monophasic defibrillation shock delivered by an implantable electrode.
ajpheart.physiology.org /cgi/content/full/286/1/H412   (3157 words)

  
 UNC BME -- Faculty (Stephen B. Knisley)
The fluorescent light intensity, which changes in proportion to changes in the transmembrane potential of cells at each recording spot, was detected with a photomultiplier tube.
Individual transmembrane potential recordings at each spot were then obtained by demultiplexing the fluorescence signal.
We think that the defibrillation shock produces rapid changes in the transmembrane voltages of cells during the time that the shock is turned on, and that these changes ultimately produce defibrillation.
www.bme.unc.edu /directory/faculty/knisley/project2.html   (427 words)

  
 Optical Transmembrane Potential Measurements During Defibrillation-Strength Shocks in Perfused Rabbit Hearts -- Zhou et ...
L is a recording region 3 mm away from the shock electrode in the left ventricle; R, a region 3 mm away from the shock electrode in the right ventricle.
Optical recordings of the effect of electrical stimulation on action potential repolarization and the induction of reentry in two-dimensional perfused rabbit epicardium.
Potential distribution in three-dimensional periodic myocardium, II: application to extracellular stimultion.
circres.ahajournals.org /cgi/content/full/77/3/593   (6846 words)

  
 Ion channel Article, Ionchannel Information   (Site not responding. Last check: 2007-10-22)
Voltage-gated channels sense the transmembrane potential and open or close in response to depolarization or hyperpolarization,respectively.
Channels differ with respect to the ion they let pass (for example, Na, Cl), the waysin which they may be regulated, the number of subunits of which they are composed and other aspects of structure.
Channelsbelonging to the largest class, which includes the voltage-gated channels that underlie the nerve impulse, consists of foursubunits with six transmembrane helices each.
www.anoca.org /channels/gated/ion_channel.html   (753 words)

  
 Modeling Electroporation in a Single Cell. II. Effects of Ionic Concentrations -- DeBruin and Krassowska 77 (3): 1225 ...
FIGURE 1 (A) Transmembrane potential and (B) pore density around a spherical cell at the end of 400-V/cm, 1-ms shock as predicted by models with non-specific (dashed line) and ion-specific (solid line) electroporation currents.
FIGURE 5 (A) Transmembrane potential and (B) pore density around a spherical cell at the end of a 400-V/cm, 1-ms shock.
Krassowska, W. Effects of electroporation on transmembrane potential induced by defibrillation shocks.
www.biophysj.org /cgi/content/full/77/3/1225   (4412 words)

  
 D.F. Davey's Teaching Resources - Membrane Potential   (Site not responding. Last check: 2007-10-22)
The membrane potential is a manifestation of a small separation of charge across the lipid bilayer of the membrane.
The lipid is the dielectric of a parallel plate capacitor in which the salty (conductive) solutions separated by the membrane are the plates of the capacitor.
Although the membrane potentials observed in cells are less than 1/10th of a volt, the electrical field is very large.
www.physiol.usyd.edu.au /daved/teaching/potential.html   (577 words)

  
 A Unified Resistor-Capacitor Model for Impedance, Dielectrophoresis, Electrorotation, and Induced Transmembrane ...   (Site not responding. Last check: 2007-10-22)
When a potential difference is applied to a cell suspension modeled by elementary cubes according to Fig.
The cell polarization is described by the potential of the external membrane side.
The contribution of the resistances to the potential distribution is frequency independent.
intl.biophysj.org /cgi/content/full/75/2/1107   (5299 words)

  
 SIMPLE TECHNIQUES SUITABLE FOR STUDENT USE TO RECORD ACTION POTENTIALS FROM THE FROG HEART -- Yoshida 25 (3): 176 -- ...
The tip of the polyethylene electrode was gently placed on the surface of the middle part of the ventricle (top trace) and another electrode at the apex or the lower part of the ventricle (bottom trace).
Note that the shape of the atrial action potential is different from the ventricular one and that the atrial and vetricular action potentials show alternate firings.
Note, that the resting potential was not affected by TTX (Fig.
advan.physiology.org /cgi/content/full/25/3/176   (4360 words)

  
 Mitochondrial Transmembrane Potential Changes Support the Concept of Mitochondrial Heterogeneity During Apoptosis -- ...
Banki K, Hutter E, Gonchoroff NJ, Perl A (1999) Elevation of mitochondrial transmembrane potential and reactive oxygen intermediate levels are early events and occur independently from activation of caspases in Fas signaling.
Bossy–Wetzel E, Newmeyer DD, Green DR (1998) Mitochondrial cytochrome c release in apoptosis occurs upstream of DEVD-specific caspase activation and independently of mitochondrial transmembrane depolarization.
Diaz G, Setzu MD, Zucca A, Isola R, Diana A, Murru R, Sogos V, Gremo F (1999) Subcellular heterogeneity of mitochondrial membrane potential: relationship with organelle distribution and intracellular contacts in normal, hypoxic and apoptotic cells.
www.jhc.org /cgi/content/full/49/10/1277   (4299 words)

  
 Mitochondrial Fusion in Human Cells Is Efficient, Requires the Inner Membrane Potential, and Is Mediated by Mitofusins ...
Inner membrane potential is required for the stimulation of mitochondrial fusion by excess mitofusin 1.
We have demonstrated that dissipation of the inner membrane potential inhibits mitochondrial fusion.
Rojo, M., Emery, G., Marjomaki, V., McDowall, A.W., Parton, R.G., and Gruenberg, J. The transmembrane protein p23 contributes to the organization of the Golgi apparatus.
www.molbiolcell.org /cgi/content/full/13/12/4343   (6581 words)

  
 Bile salt-induced apoptosis in human colon cancer cell lines involves the mitochondrial transmembrane potential but not ...
Bile salt-induced apoptosis in human colon cancer cell lines involves the mitochondrial transmembrane potential but not the CD95 (Fas/Apo-1) receptor.
METHODS: CD95 expression was correlated to DC-induced cell death in four colon cancer cell lines.
Mitochondrial transmembrane potential (MTP) was determined in whole cells as well as in isolated mitochondria.
coloncancer.researchtoday.net /archive/2/2/801.htm   (386 words)

  
 Vesicle transmembrane potential is required for translocation to the cytosol of externally added FGF-1
The vesicular electrical potential was found to be crucial for translocation of the growth factor.
Therefore, the possibility existed that the inside-positive electrical potential across the vesicle membrane (Van Dyke, 1988; Sonawane et al., 2002) generated by V-type proton pumps could be required for translocation.
Thus, the membrane potential is likely to influence the structure of the transmembrane part of FGF receptors and it could affect intracellular trafficking of the growth factor−receptor complex (Clague et al., 1994).
www.nature.com /cgi-taf/dynapage.taf?file=/emboj/journal/v21/n17/full/7594688a.html   (7827 words)

  
 Transmembrane Potential Properties at the Core of Functional Reentrant Wave Fronts in Isolated Canine Right Atria -- ...   (Site not responding. Last check: 2007-10-22)
Transmembrane Potential Properties at the Core of Functional Reentrant Wave Fronts in Isolated Canine Right Atria -- Athill et al.
B, Pacing immediately after episode recorded in A. Note that resting membrane potential is same as that in A and that normal action potential amplitudes are recorded.
In 2 episodes of reentry, the cell at the core remained unexcited at its resting membrane potential.
circ.ahajournals.org /cgi/content/full/98/15/1556   (5002 words)

Try your search on: Qwika (all wikis)

Factbites
  About us   |   Why use us?   |   Reviews   |   Press   |   Contact us  
Copyright © 2005-2007 www.factbites.com Usage implies agreement with terms.