Table 6. Estimated Parameters.

Variable	Unit	Description
Xi = 118	fmol	number of impermeable ions in the cell, set by electroneutralitye
Xp = 4.21	fmol	number of impermeable ions in the PCL, to 0.2% isosmolaritye
Xs = 16.6	mM	concentration of impermeable ions in plasma, set by electroneutralitye
GBHyC = 10	fS/μm2	$\text{maximum conductance of basolateral}{\text{HCO}}_3^{-}\text{channel per unit}{\text{area}}^{\mathrm{d}}$
GBHC = 50	fS/μm2	maximum conductance of basolateral H+ channel per until aread
GNHE1 = 0.1	fM.μm/s	maximum conductance of basolateral NHE1d

^dAssuming an open probability of one,

^eequilibrium values were used for setting electroneutrality and isosmolarity conditions. Compartmental osmolarity is found to be ≈ 281 mOsm; slightly less that 331 ± mOsm found in normal and CF nasal epithelia by Zabner et al. (1998). The concentration of impermeable ions at equilibrium in the PCL is ≈ 22 mM, in good comparison to an estimate by Tarran et al. (2001) to be around 40-50 mM.