Talk:Voltage clamp

message: I've moved this page from Electrophysiology, which I thought was too long.  I've been working to clean it up, but it still needs work. Here's some material that I took off the page because I thought it was too informal and maybe not necessary. delldot | talk 04:08, 25 November 2005 (UTC)
thread_title: Untitled

message: The article states with a reference that voltage gated channels operate normally. Is this correct? Clamping the membrane voltage interferes with the voltage gated channels. I'm revising to reflect this Kghose 01:36, 7 January 2007 (UTC)
thread_title:  Voltage gated channels and voltage clamp 

message: Can this be found anywhere else? The links http://www.moleculardevices.com/pages/instruments/axon_guide.html and http://www.moleculardevices.com/pdfs/Axon_Guide.pdf both seem to be broken.
130.243.156.168 (talk) 20:47, 7 May 2012 (UTC)
thread_title:  Broken link - Axon Guide? 

message: I found the first sentence of this article:
"The voltage clamp is used by electrophysiologists to measure the ion currents across the membrane of excitable cells, such as neurons, while holding the membrane voltage at a set level." 
To be a bit confusing. Initially I thought "one doesn't measure a current across something, you measure the current through something (in normal circuit analysis you do this by breaking the circuit and adding a current measuring device such as an ammeter to close the circuit again). Current is literally the measure of electrons flowing through a given point. You do however measure the voltage (literally the difference in electrical potential-a.k.a electro-motive force) between 2 points, or across something.
However several following statements in the article seem to suggest that the concept of current being referred to cannot be accurately applied to the way that I understand it (viewing It from the perspective of a person who studies electrical engineering).
It makes sense to me that a voltage clamp is a way of taking variations in voltage across the cell's membrane out of the equation,  and that by keeping them constant, eliminates one variable so that the V in Ohm's law becomes a constant and the I and R can then be measured, and their implications as they pertain to ion channels and ion flux throughout a cell be deduced successfully. 
The first sentence just struck me as perhaps wrong, or possibly just rather unclear and hard to parse. Of course there's the very real possibility that I'm wrong, because as I alluded to I'm not an electrophysiologist.  — Preceding unsigned comment added by 71.204.252.142 (talk) 05:33, 9 January 2013 (UTC)
replies: text: Hi, I'm an electrophysiologist by background, but I also believe strongly that Wikipedia needs to be written for non-specialists. I've just spent a long time staring at that sentence in response to your comments, and I ended up changing "across" to "through", while also feeling a little ambivalent about that edit. Your understanding is entirely correct, but the paradox of terminology arises, I suspect, from the biochemical structure of biological membranes. The currents in question do indeed travel through the central pores of individual ion channel proteins. But there are many such proteins, spread out side-by-side in the lipid bilayer of the cell membrane, so it's more like a very large number of wires in parallel. Electrophysiologists who study single ion channels via patch clamp often say that current goes "through" the channel proteins, but electrophysiologists who do voltage clamp at the whole-cell level are more likely to say "across", probably because it's not quite logical to think of current going through the whole membrane, most of which is the non-conducting lipid bilayer. Ultimately, I think "through" and "across" are almost interchangeable in meaning here, so I guess it's probably better to say "through" in this sentence. --Tryptofish (talk) 00:53, 10 January 2013 (UTC)
thread_title:  First sentence - incorrect terminology/confusing phrasing? 

message: Can someone add an example what happens with the current (that can apparently also be recorded) during an action potential? I would add in the abstract: For exmaple, during an action potential of an excitatory cell (positive voltage) the recorded current would be negative. Would that be correct, and possibly help further readers? If yes, please add, or confirm and I'll add. The reason to add is the confusion between flow of ions (as already stated in abstract) and recorded current (EPSC?).
Source
Greetasdf (talk) 11:25, 15 March 2021 (UTC)
thread_title:  current during AP in voltage clamp