Fig. 5. The dependence
of the channel selectivity on the salt gradient across the membrane. Ion
selectivity was quantifies as the zero-current potential (reversal
potential) in the presence of a KCl salt gradient.
The low-salt side was always at a KCl activity of 0.06 while the high-salt
side was varied as indicated. The lines
represent the different theoretical predictions
of different theories: GHK is Goldman/Hodgkin/Katz; LCT (arithmetic) and
LCT (harmonic) are two versions of the
large channel theory. Reproduced with permission
from Zambrowicz and Colombini (1993).