Cystic fibrosis transmembrane conductance regulator and Na+channel subunits mRNA transcripts, and Cl−efflux, show a different distribution in rat duodenum and colon

Aim: We compared the distribution and putative association of Cl– channel transport, CFTR mRNA transcripts, and Na+ channel (ENaC)α- and β-subunit mRNA transcripts in villus and crypt epithelial cells of duodenum, with corresponding surface and crypt cells of colon from sodium-depleted rats. Methods: Cells were loaded with 36Cl– and forskolin-stimulated efflux was determined. RT-PCR was performed for CFTR mRNA transcripts and ENaC α- and β-subunit mRNA. Duodenal epithelial cell response to VIP was assessed by measuring intracellular cAMP. Results: Forskolin-stimulated Cl− efflux occurred with decreasing magnitude in duodenal crypt, duodenal villus, colonic crypt and colonic surface cells in Na+-depleted animals. CFTR expression was correlated directly with Cl− efflux (r = 0.91, P