IUBio Biosequences .. Software .. Molbio soft .. Network News .. FTP

Goldman-Hodgkin equation : origin ??

Richard Norman RNorman at msn.com
Fri Feb 16 16:16:20 EST 1996


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 
related mobility,
and currents driven by potential gradients.  Integrating the two 
means choosing
whichever notation best suits your application.





More information about the Neur-sci mailing list

Send comments to us at biosci-help [At] net.bio.net