Finally, no systematic differences were observed in cell volume in cells 
expressing high quantities of CFTR, nor any inhibition of the capacity of cells to 
regulate their volume in response to osmotic stresses (data not shown). 
IV.B.3.C. Overexpression of CFTR and Cl' conductance in the apical 
membrane of airway epithelial cells 
It is important to test whether Cl' conductance in the apical membrane is 
regulated in part by factors other than the level of CFTR protein expression. This 
question was addressed in the studies of the percent correction CFT1 studies 
described above. As shown in Figure 12, an interesting feature is that the ability of 
the epithelial monolayer to secrete Cl' is no different when 10% of the cells are 
corrected as compared to when 100% of the cells are corrected. These data indicate 
that a functioning monolayer has mechanisms to physiologically coordinate the level 
of apical membrane Cl" conductance with other cellular parameters, e.g., 
basolateral membrane K + channels, necessary for regulated Cl" secretion. 
IV.B.4. Effect of recombinant adenovirus on barrier function of airway 
epithelia 
A series of studies were designed to define whether administration of Ad5- 
CMV-lacZ or Ad5-CB-CFTR damaged the barrier function of airway epithelia. For 
these studies, nasal epithelial cells obtained from normal subjects or CF patients 
were plated on collagen matrices and the formation of an intact epithelial barrier 
measured by the development of a transepithelial resistance (R t ). The effects of 
adenoviral administration on day 2 in culture versus day 3 in culture on 
transepithelial resistance of these preparations was compared to a vehicle control. 
As shown in Figure 22 (below), no changes in resistance were seen in monolayers 
exposed to Ad5-CMV-lacZ (MOI-10,000) or Ad5-CB-CFTR (MOI-10,000) as 
compared to vehicle. Thus, it appears that in acute in vitro studies, recombinant 
adenoviruses do not perturb mucosal barrier function. 
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Recombinant DNA Research, Volume 17 
