ketamine/xylazine in preparation for in situ functional assays. The basic concept is 
to measure transepithelial potential difference (PD) in response to various stimuli. 
The ground electrode is placed subcutaneously and the measuring electrode is 
placed in the graft lumen bathed in the indicated solution. The initial measurement 
is made in the presence of 120 mM Cl". The luminal bath was subsequently changed 
in the following way: a) amiloride is added, b) Cl" is decreased from 120 to 3 mM, 
and c) forskolin is added. 
Results obtained with xenografts derived from a non-CF and CF individuals 
are summarized in Figure 17 (panels A and B respectively). Introduction of the Na 
channel blocker amiloride to the lumen bath leads to a drop in PD (i.e., less 
negative) in both non-CF and CF grafts. The PD increases (i.e., become more 
negative) in a stepwise manner in the non-CF graft when luminal Cl" is decreased 
(representing basal conductance through CFTR) and when CFTR is stimulated with 
forskolin. 
Panel A (Non-CF) 
Panel B(CF) 
Panel C (CF/CFTR) 
Panel D (CF/lacZ) 
Bioelectric characterization of Cl* transport across surface epithelium of xenografts in situ. Panel 
A- non-CF graft; panel B- CF graft; panel C- CF graft infected with Ad5-CB-CFTR; and panel D- 
CF graft infected with Ad5-CMV-CFTR. 
Figure 17. Analysis of CF electrolyte phenotype in xenografts. 
CF xenografts exposed to Ad5-CMV-lacZ or Ad5-CB-CFTR were subjected 
to similar studies. The CF graft exposed to Ad5-CMV-lacZ (Figure 17, panel D) 
was indistinguishable from the noninfected CF graft (Figure 17, panel B) while the 
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Recombinant DNA Research, Volume 17 
