potassium

Michael Wehner MWehner at abalkin.wupper.de
Mon Sep 25 11:06:13 EST 1995


In article <4448tc$joq at merkurius.lu.se>, biv94cjn at lustudat.student.lu.se 
(Armilius) writes:
> If you put potassium in the extracellular fluid outside a frog nerv. 
> What is happening to actionpotential then?. What is happening to 
> the cellmecanism? What is happening to the membranpotential. 
>  
> Sincerly regards Carl-_Magnus 
>  

Hi there,

I personally never checked it out, but according to common sense and the 
Nernst- equatation, it will lower the membranpotential, because the gradient 
for potassium inside vs. outside is lowered. Depending on the potassium amount 
in the bath the resting potential is approaching the activation- threshold, 
resulting in a higher excitability, after that, continiously increasing the 
extracellular potassium amount, the membranpotential will break down, 
resulting in a quiet nerve. 
These problems are well known in medicine, as a consequence of tourniquet- 
syndrom or renal- failures, both resulting in a hyperkaliema with the problem 
of cardiac dysrhythmia/arhythmia (and other neurological symptoms).

You can read this (better and in more detail) in all regular neuroscience 
textbooks.

Michael.







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