Why does the Nernst Equation work for Resting Potentials?

Terrence M. Brannon brannon at sapo.usc.edu
Wed Jun 26 10:00:16 EST 1996

Let's just take a glial cell which only has resting (permanently open)
channels for K+. This glial cell also has Na+, Cl- on the outside and
inorganic anions on the inside, though only K+ can move freely from
one side to the other. 

The Nernst Equation calculates the resting potential of a glial cell
based solely on the valence, and intra and extra cellular conc. of K+
as well as the gas constant and temperature. 

My question is: don't Na+ and Cl- and the inorganic anions create a
charge which the K+ must respond to in its passive diffusion?

terrence brannon brannon at rana.usc.edu      telephones: home: 213-386-3659 
3215 San Marino St. #7, LA, CA 90006  /o)\       office: 310-822-1511x308 
http://rana.usc.edu:8376/~brannon     \(o/              fax: 310-823-6714 

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