Hyperpolarization of Neurons

Rifle River jstream at girch1.med.uth.tmc.edu
Fri Apr 29 09:54:53 EST 1994


In article <2potfp$gpi at news.arc.nasa.gov>, brp at neuron.arc.nasa.gov (bruce
raoul parnas) wrote:

> Actually, the negative resting potential derives even more from the Nernst
> potentials for the various ions present internally and externally.

Bruce, this is an excellent statement and it gets to the heart of the
reason
why the potential is negative (i/o).

> The
> resting potential would be negative even in the absence of any sort
> of pump mechanism.

However, this statement might be contradicted by some "sticklers".
Using, ouabain to inhibit the Na/K pump the squid  giant axon can
maintain its normal resting potential and it can fire action potentials
repeatedly (I don't recall the exact number but I think it was thousands).
However, without the Na/K pump the ion gradients will eventually be
depleted upon repetitive firing.  Therefore, one could conclude that
the Na/K pump is necessary, in the long run, for proper resting potential
and for repeated firing of action potentials. 

BTW, I think most neurons can't fire near as many action potentials as
the squid giant after inhibition of the Na/K pump. 


+++++++++++++++                  
Rifle River                      
jstream at girch1.med.uth.tmc.edu    
                                 



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