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[Neuroscience] Re: membrane voltage equations which one

Bill via neur-sci%40net.bio.net (by connelly.bill from gmail.com)
Mon Sep 6 16:27:23 EST 2010


Or I suppose you could get really nerdy and replace the simple ohmic
behavior of an ion channel with its true, Goldman-Hoxgkin-Katz
rectification
Flux*area=P.z^2. (V.F^2)/(RT). ([Ion]i - [Ion]o.e^(-z.V.F/RT))/(1-e^(-
z.V.F/RT))

I wonder what happens to the shape of the action potential if you take
that into account? Probably not a lot seeing as the important fluxes
take place so far from the reversal potentials.

On Sep 7, 12:34 am, r norman <r_s_nor... from comcast.net> wrote:
> On Sun, 5 Sep 2010 20:13:26 -0700 (PDT), Bill
>
> <connelly.b... from gmail.com> wrote:
> >On Sep 6, 11:07 am, Bill <connelly.b... from gmail.com> wrote:
>
> >> where I = Ó Gx (Ex-V)
>
> >That "Ó" was supposed to be a SIGMA... sum of all Gx(Ex-V) across all
> >ions
>
> This is a better account of what is really happening in the cell.
>
> My simplified equation represented the membrane as a simple RC
> circuit, something useful in computing cable properties for example.
>
> Bill's addition expands the ionic current into the separate sodium,
> potassium, and other components reflecting the way that ohmic current
> really crosses the membrane and also accounting for the fact that each
> separate ionic current involves a reversal potential or Nernst
> equilibrium.
>
> It only lacks the inclusion of current derived from, for example, an
> external stimulus, but that is easily added to the sum.



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