Talk:Resting potential

Untitled
Could someone put in the values for the permeabilities in a typical cell? like calculate how the Nernst equals -70mV at rest? 129.31.72.52 21:37, 19 June 2007 (UTC)

Citations needed?
For such a long text on such a science-heavy subject, it has very few citations? I feel there are a lot of facts in there which it wouldn't hurt to give sources for. For instance, why is the resting potential pegged at -70 mV? Who measured that? --Miturian (talk) 09:48, 9 January 2014 (UTC)

Context
Could someone please extend the first sentence to include something like "...is a term in [whatever] biology" so that people like me, using "random article" to check stuff, know in what context this term is used? Is tis molecular or cell biology? Tierlieb 19:48, 2 November 2007 (UTC)

im a first year undergrad, so far this term came up in a lecture for psychobilogy —Preceding unsigned comment added by 137.205.77.223 (talk) 01:34, 15 May 2008 (UTC)

Reorganizing the field of MEMBRANE POTENTIALS
There are three articles now which discuss very much the same things with numerous repetitions and description of the same material in different terms. As it was already suggested by Methoxyroxy 12:37, 2 November 2006 (UTC), it needs a really big clean-up and optimization. There is a lot of confusion there so I will do this albeit not at once. I will move different parts between these three articles, edit and unify their style etc. At later stage I will need someone who is native English speaker to do spellcheck.Rvfrolov (talk) 20:52, 2 January 2009 (UTC)
 * Resting potential
 * Membrane potential
 * Action potential
 * I have replied at Talk:Membrane potential. Looie496 (talk) 22:00, 2 January 2009 (UTC)

Reorganizing the field of MEMBRANE POTENTIALS-2
The article will be messy for a while until i finish editing. It may take several daysRvfrolov (talk) 22:41, 2 January 2009 (UTC)

You are right. Worse, there is no mention here of potassium leak channels, the ones that set the resting potentials. Uniporters are oddly credited? —Preceding unsigned comment added by Cagedcalcium (talk • contribs) 01:11, 11 September 2009 (UTC)
 * As often happens on Wikipedia and elsewhere, "several days" turned into "never". If you see a way to improve this article, you should go ahead and do it.  Regards, Looie496 (talk) 02:59, 11 September 2009 (UTC)

physiological?
Someone wrote "At physiological temperature, about 29.5 C" surely physiological temperature is 37°C? Citation anyone? 83.146.15.190 (talk) 18:34, 27 April 2009 (UTC)
 * Experimental studies of dissociated cells or brain slices (usually from rats) are often conducted at temperatures below normal body temp. That's probably what "physiological temperature" is supposed to mean here.  It's easier to maintain a healthy preparation at those temperatures.  I agree that this should be clarified, but this article is a bit too technical for me to work on. Looie496 (talk) 19:00, 27 April 2009 (UTC)
 * Yes, it should be at 37°C . I might calculate the right values at 37°C if i think about it :) Trancelot (talk) 14:49, 17 January 2013 (UTC)

Negativity of the resting potential
The article does not explain why the resting potential is negative despite both media having zero global charge. Which I believe is due to negative charged proteins inside (although I don't understand how does this not violate zero global charge). It also does not mention that the membrane potential is given by Vm = Vin - Vout. Rend (talk) 20:06, 18 March 2010 (UTC)
 * This seems to be one of those pages that is chronically in need of work. I agree with you that an improved "measuring" section would do well to mention in-minus-out (although that's true for any membrane potential, not just at rest). The answer to the first part of your question is selective permeability, so K+ leaves the cell, leaving impermeant anions (including but not limited to proteins) behind. The page sort of addresses this, but obviously not very well. --Tryptofish (talk) 21:14, 18 March 2010 (UTC)
 * Yes, the article does at least try to explain why the resting potential is negative -- it's a consequence of the Goldman equation. The reason the article does not mention that Vm = Vin - Vout is because I thought it wouldn't be helpful.  Every measured voltage is actually a voltage difference, so to explain what Vin and Vout are, you have to bring in the concept of a voltage reference point.  Thus Vin and Vout are each, when properly understood, actually more complicated than Vm is.  Maybe the concept needs to be explained anyway, but my first intuition was that it would be best to gloss over the issue.  Regards, Looie496 (talk) 01:21, 19 March 2010 (UTC)

Much to wordy
This article is not very reader friendly. I made just one simple change, but it is only one of many needed. The article is much too wordy. I understand that the average person will not be able to understand the article. However, keep in mind that many beginning students will come to this page seeking help. It should be ESPECIALLY for them. That's the purpose of wiki; its not a platform to pontificate. I suggest going through this and making similar changes as I did, ionic species-simplified as ions. Seriously? —Preceding unsigned comment added by 72.213.53.41 (talk) 07:14, 19 March 2011 (UTC)

Tags
I am going to remove the "lead too long" and "refimprove" tags added to this article today. The lead is not overly long given the length of the article, and the need for references doesn't require a tag to be noticed. There is no doubt that this is a pretty low-quality article which needs improvement in numerous ways, but defacing it with big ugly tags at the top doesn't promote that, in my opinion. Looie496 (talk) 17:08, 19 March 2011 (UTC)

Millman Eq. appears to be wrong in this page
I think ion permeabilities in Millman equation should be replaced by conductances. Ref: Ove Sten-Knudsen, "Biological membranes: theory of transport, potentials and electric impulses", Cambridge University Press, 2002, p. 382 — Preceding unsigned comment added by Hamid.mirzaei (talk • contribs) 18:25, 12 December 2011 (UTC)
 * If you are confident about that, please feel free to fix it. If you have difficulties with formatting, I can probably help with that.  Regards, Looie496 (talk) 18:54, 12 December 2011 (UTC)

Regulation?
An essential point is missing: Is Na+/K+-ATPase working until ATP is exhausted? Or until there is no Na+ or K+ to be pumped? Probably there is some sort of negative feedback. But how can cAMP measure the Membrane potential, because it is no Transmembrane protein ? The negative feedback should be slow enough (T > 10 ms) not to prevent the emergence of the Action potential. Who knows a correct answer? --92.193.88.132 (talk) 17:36, 6 March 2012 (UTC)
 * I don't think this page says anything like that about cAMP. What happens is that there is a steady state between the effects of the ATPase and the opposing effects of leakage channels (principally K+). Nothing is really depleted. --Tryptofish (talk) 01:37, 7 March 2012 (UTC)

Basic Questions

 * "there is no actual measurable charge excess in either side. That occurs because the effect of charge on electrochemical potential is hugely greater than the effect of concentration so an undetectable change in concentration creates a great change on electric potential."

Can this sentence be clarified, specifically:

the effect of charge on electrochemical potential significantly larger then the effect of charge on concentration - is this a general statement or true in all cases?

And if charge is more significant then concentration in influencing electrochemical potential why does a small change in concentration greatly effect electropotential? Or does it mean electrochemical potential? Either way how does it make any sense, is it correct or nonsense and what is the exact meaning behind the message?

I am a beginning student trying to wrap my head around the fundamentals of membrane potential physiology. A couple of other questions I have:

1) What is the reason Na+ stays at its location right across the barrier on the extracellular side of the membrane? Diffusion? Electrochemical potential? Electric Charge repulsion?

2) If the answer is the electrochemical gradient/potential, because it is trying to move to a "less" positive potential.. if its located extracellularlly isn't that the "great unknown" where any molecules/cells/protein etc. are able to float by and possibly influence it? What happens if one of these has a "LESS" positive potential then the membrane that Na+ is currently attracted?

3) Can someone explain why can't Na+ be used for the entire process to establish the same voltage interactions leading from resting to action potential (as long as thier was less concentration intracellularly... if it is about LESS positivity ..Or vice versa for K+?)? — Preceding unsigned comment added by Trancelot (talk • contribs)


 * Regarding the first question, the basic fact is that electrical forces are so strong that even a tiny excess of charged particles creates a huge electromotive force -- that's a general principle. Regarding the rest, can I suggest that you take a look at the membrane potential article?  It's written in a quasi-tutorial way, and serves as background for our other articles about cellular electrical activity.  Regards, Looie496 (talk) 17:15, 17 January 2013 (UTC)

Proposed external link
Some time ago I wrote an interactive tutorial on the origin of the resting membrane potential which is available on my university website: http://www.st-andrews.ac.uk/~wjh/neurotut/mempot.html I have received some positive (unsolicited) feedback from a number of neuroscience students and staff in various other institutions, and I think it answers some of the questions raised on this talk page. I'm therefore minded to put a link to it in the "External links" section of the article. But I wrote it, and I don't want to contravene vanity publishing guidelines, so I thought I'd put it here for a while and see if there were any strong opinions against doing this. Wjheitler (talk) 20:05, 27 September 2013 (UTC)
 * I think it's great, but it might make more sense to add a link from the membrane potential article rather than from here. That's really the "base" article for all aspects of this topic, and it seems like your tutorial would be helpful in understanding it. Looie496 (talk) 22:21, 27 September 2013 (UTC)

Assessment comment
Substituted at 04:11, 30 April 2016 (UTC)

Generation of the resting potential
If simple diffusion is meant to be a passive mean where each ion is independent from each other ion IN each side AND in each compartment.

Then a electric gradient is meant to be an active mean where each ion becomes dependent to each ion OR electrode IN each side AND each compartment.

An electric gradient EXCLUDES all passive mean thus a simple diffusion can't exist when there is a potential difference. Somasimple (talk) 08:38, 27 August 2018 (UTC)


 * That whole section of the page is horribly written. I deleted the word "simple" per your comment. But diffusion in this case need not be passive in the way that, for example, gas molecules spread out due to entropy. Ion movement driven by an energy difference can be considered active rather than passive, but still be diffusion in the sense of increasing entropy. Here, it is contrasted with, for example, active transport. --Tryptofish (talk) 19:17, 27 August 2018 (UTC)


 * I agree with an entropic change but a ion movement may be passive (like thermal motion aka Brownian) but if this ion enters in an electric field (because there is a potential difference) then the ion is driven by the electric field, the passive force is replaced by the electric one. Since the electric field is directed towards the membrane, the potassium CAN NOT go out and the negative ions are expelled. The strength of electric forces is EVER stronger than thermal agitation. That's the basis of every electrochemistry experiment. --Somasimple (talk) 05:11, 28 August 2018 (UTC)


 * I agree with everything that you said. In a biological or cellular context, it's traditional to make a distinction between passive transport and active transport, with the difference between those two terms depending upon whether energy is obtained from ATP as a direct cause of the transport. Membrane proteins like ion channels move ions under the influence of electrical and concentration differences, but do not derive energy from ATP. In contrast, transport proteins use ATP to transport molecules or ions against an electrochemical gradient. The way that this page is currently written is very bad, and it really needs a major rewrite. --Tryptofish (talk) 21:52, 28 August 2018 (UTC)
 * Here is an image that shows the steady state described in the Wiki. The green arrows show the electric flow directions. It shows how the concentrations of the NE or GHK concentrations are separated by the electric field that move POSITIVE AND NEGATIVE ions in wrong directions by the theory Resting_potential. Ions locations in resting potential.png --Somasimple (talk) 09:21, 31 August 2018 (UTC)

Electroneutrality
So we admit the electroneutrality is slightly violated across the membrane. The external milieu contains a little amount/imbalance m of positive ions. Here is a picture of the problem So we expect that for 2 cells the model works and we have now (see picture) and if we have 100 cells we get (see picture) THE VIOLATION GROWS AS THE CELL COUNT GROWS!!! But a cell contains only a m imbalance but sees n*m positive ions outside! This model seems not valid.Somasimple (talk) 11:16, 29 August 2018 (UTC)
 * Membrane potential, Nernst equation, Hodgkin-Huxley model. --Tryptofish (talk) 21:18, 29 August 2018 (UTC)
 * Thanks for the replies. I read carefully the pages you cited but didn't find any sentence or phrase neither a single equation that may address the situation I had described. All the pages describe a 1/1 relation where the problem comes with a 1/N relation. It seems that NOT a theory was tried with at least 2 cells or more. It is a simple computation that is not contestable 1 cell equals to a m positive charge imbalance, 2 cells => 2m positive charge imbalance but the the cytosol of a cell MUST contain only m negative ions excess. So you get a problem you have too much positive ions outside. May I ask how the plugs (external and internal dots) of the HH model are wired?--Somasimple (talk) 05:21, 30 August 2018 (UTC)
 * If there is a battery between the two sides of a membrane, you can't say it is connected or not! Battery cell.png SEE PICTURE--Somasimple (talk) 07:33, 30 August 2018 (UTC)

Goldman voltage equation not correct!
In my opinion and in accordance with the text the equation should contain RELATIVE permeabilities. At the moment all the permeability-quotients are one. — Preceding unsigned comment added by Koitus~nlwiki (talk • contribs) 18:27, 19 October 2018 (UTC)
 * It does not matter at all. There is no electrons flux in solutes (Chemistry) so you can't apply electric rules in solutes.--Somasimple (talk) 07:42, 7 November 2018 (UTC)

2 conflicting equations for Resting Potential
The article correctly states that when a membrane is permeable/conducting to 2 or more ions with different Nernst potentials a steady-state will be reached where the net flux/current is zero, and this steady state occurs at a membrane potential which is, qualitatively, a compromise between the relevant Nernst potentials. However, although 2 different equations are given to describe this compromise, the 2 equations are actually incompatible with each other. The first assumes the conductances are fixed and unrelated to the ion concentrations (which enter only via the Nernst potentials), while the second assumes the permeabilities are fixed, and that the ions move independently of each other. This confusion is common in most elementary accounts of resting potential. The correct view is that both equations are useful simplifications which make different assumptions about how ions actually move, and a better but far more complicated account could be given by specifying the detailed ways ions move through the various types of channels. based on their structures. I recommend the article be modified to say that there are 2 widely used but different ways to quantitatively describe resting membrane potential: one assumes the I-V relations are straight (which they rarely are when the Nernst potentials are nonzero) and the other that ions move independently. These assumptions lead to slightly different equations - one involving weighted sums of logarithms of concentration ratios, the other involving logarithms of weighted sums of concentration ratios. There is no good simple way to avoid this issue.

The other crucial issue is, which types of ion channel are actually involved in generating the resting potential? The article correctly says that the dominant channel is potassium (specifically, mostly 2p-domain K channels), but doesn't really clarify which other types of channel (primarily sodium) are also, to a lesser degree, involved. Recent evidence suggests that a unique channel type, NALCN, provides the long-sought sodium leak conductance (Lu, B., Zhang, Q., Wang, H., Wang, Y., Nakayama, M., and Ren, D. (2010); Ren,D. Neuron 72, December 22, 2011 ª2011. Extracellular calcium controls background current and neuronal excitability via an UNC79-UNC80-NALCN cation channel complex. Neuron 68, 488–499; Kschonsak, M., Chua, H.C., Noland, C.L. et al. Structure of the human sodium leak channel NALCN. Nature (2020). https://doi.org/10.1038/s41586-020-2570-8 It's rather unfortunate that the most basic feature of electrophysiology, the resting potential, is actually rather difficult to explain succinctly and correctly! This is not the fault of the primary author of this article, since most standard texts also flub the issue.Paulhummerman (talk) 21:58, 13 October 2020 (UTC)