Permeability vs. Conductance:
Mathew V. Jones <jonesmat at ohsu.edu> writes:
> The way I usually think about it is that higher relative permeability
> means a better ability to compete with other ions for occupancy of
> the pore. This can also be (but doesn't have to be) thought of as a
> long dwell time in the pore relative to other ions. On the other hand,
> ions that stay in the pore for a long time give rise to smaller
> currents (number of ions passing through the pore per unit of
> time). That means that ions with very high relative permeabilities may
> have small conductances. And in any case, neither of these things are
> related to the "state of openness of channels" because conductance refers
> only to the open channel, and relative permeability is measured by
> comparing reversal potentials while holding gating properties constant.
True! But do you think someone who doesn't even know a citation for
Hodgkin-Katz is ready for this detail? Also, don't ions that stay in the pore
for a long time also have lower flux rates and hence lower permeabilities?
I thought permeability related to diffusion coefficient and flux driven by
concentration gradients while conductance related to the closely
and currents driven by potential gradients. Integrating the two
whichever notation best suits your application.