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

H. S. Odes*, P. Smirnoff, R. Guberman, S. Pollak-Charcon, A. D. Sperber, A. Fich, G. M. Fraser, B. Schwartz

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

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 < 0.01). Na+ channel α-subunit was expressed in colon and duodenum in animals fed diets with a high or low sodium content. While the β-subunit mRNA was detected in the colon of sodium-restricted rats, it was absent in the duodenum under control conditions and after Na+ restriction. There was an inverse correlation between mRNA transcripts for CFTR and the ENaC α-subunit (r = -0.93, P < 0.003) and β-subunit (r = -0.91, P < 0.004) in colon. VIP-stimulated cAMP in duodenal epithelial cells was greater in crypt than villus (P < 0.05). Conclusion: Cl- efflux, CFTR transcription and forskolin-stimulated cAMP activity occur in both crypt and villus epithelial cells in duodenum. Possible interaction between CFTR and Na+ channels is apparently limited to parts of the colonic crypt. Lack of duodenal β-subunit expression makes ENaC activity unlikely.

Original languageAmerican English
Pages (from-to)231-240
Number of pages10
JournalActa Physiologica Scandinavica
Volume178
Issue number3
DOIs
StatePublished - 1 Jul 2003

Keywords

  • Cl
  • Cystic fibrosis
  • Intestine
  • Na
  • Transmembrane conductance

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