Ca-dependent channel

[shimon]

hi,
How do I turn the slow activating K+ channel (Im) to be both VOLTAGE AND CALCIUM dependent?

thanks in advance,

sh.

[ted]

Your choices:
1. Best: find NMODL source code, or a configured Channel Builder, created by
someone else that does exactly what you want. Try looking in ModelDB.
2. Find one or more mechanisms built with NMODL that do almost what you
want, and use the principle of "programming by example" to come up with
your own new mechanism. Try ModelDB, or look at cagk.mod in
C:\nrn60\examples\nrniv\nmodl
(UNIX/Linux/OS X users: get the gzipped source files and look in
share/examples/nrniv/nmodl).
3. Use the Channel Builder to construct a model that combines voltage-gated
and ligand (cai) gated states.

Regardless of which approach you take, test the mechanism extensively to
make sure that it does what you want it to do.

[shimon]

thanks for you answer.

but still -
the cagk.mod file describes the channel as voltage dependent in this way: voltage and calcium INCREASE the conductance. I want to describe a voltage gated channels in a way that the CALCIUM DECREASES its conductance....

[ted]

So replace the bit that specifies the cai dependence of the conductance
with whatever kinetic scheme or mathematical formula you have in mind.