Access potassium sub-currents?

[mjb7]

I have a model that includes potassium accumulation. There are several conductance channels that contribute to the overall potassium current (ik). The .mod files for all of the potassium current mechanisms include the "USEION k READ ek WRITE ik" statement. I would like to know how I might access the sub-current associated with a specific one of these mechanisms.

[ted]

Assuming a density (distributed) mechanism with SUFFIX whatnot

In the ASSIGNED block declare
i (mA/cm2)

In the BREAKPOINT block replace
ik = whatever_your_formula_is
with
i = whatever_your_formula_is
ik = i

In the NEURON block declare
RANGE i

Then your mechanism will not only handle conservation of charge and mass properly (because of its USEION k . . . WRITE ik statement) but you will also be able to discover exactly what your mechanism contributes to ik--this value will be known to hoc as i_whatnot

A nearly identical tactic suffices for dealing with a point process (only differences: units of i will be nA, and i will be known to hoc as foo.i where foo is an objref that points to an instance of the point process's class).

[mjb7]

Ah, yes. Thank you Ted for responding so quickly!

[ted]

Glad to be of help. Thanks for using NEURON in your research. When you publish, please be sure to cite NEURON
see viewtopic.php?f=22&t=73
and send me a citation of your article so we can add it to the on-line bibliography.