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From: "Enric Claverol" <enric@caltech.edu>
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Subject: Diffusion/Resistivity of ions in solution
Date: Wed, 9 May 2001 23:02:42 -0700
Organization: California Institute of Technology, Pasadena
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Dear all, any help on the following matter will be apreciated. Thanks in
advance.

I normally culture neurons using a classical solution cosisting, basically,
of
physiologically common ions Na,Cl,K dissolved in water plus additives which
potentiate cell development.
I am interested in substituting this solution (which for the purposes of
this email
can be taken to be typically 150 mM NaCl in water) by
an alternative with the property that the diffusion coefficient of the ions
(mostly K, Na and Cl)
is increased with respect to the water based solution that I am using now. I
aim at finding
a substance with a higher electrical resistivity but still "likable" by my
neuronal cultures.

I know of gelly collagen/laminin/agarose based substrates where neurons
appear
to develop as well as in pure water based solutions. However,  I  would like
to
be able to anticipate the electrical resistivity of the medium before even
initiating
the experiment with cells in oder to choose the medium that will give me the
higher resistivity.

I have some quantitative estimations for KCl solutions in proteic gels but
all the
information is sketchy. It seems like if collagen will not give a large
increase in resistivy
(about a factor of 2) where as I aim at a factor, at least, 10.

enric





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