CFTR Upregulates the Expression of the Basolateral Na(+)-K(+)-2Cl(-) Cotransporter in Cultured Pancreatic Duct Cells

Am J Physiol. 1999 Dec;277(6):C1100-10. doi: 10.1152/ajpcell.1999.277.6.C1100.

Abstract

The purpose of the current experiments was 1) to assess basolateral Na(+)-K(+)-2Cl(-) cotransporter (NKCC1) expression and 2) to ascertain the role of cystic fibrosis transmembrane conductance regulator (CFTR) in the regulation of this transporter in a prototypical pancreatic duct epithelial cell line. Previously validated human pancreatic duct cell lines (CFPAC-1), which exhibit physiological features prototypical of cystic fibrosis, and normal pancreatic duct epithelia (stable recombinant CFTR-bearing CFPAC-1 cells, termed CFPAC-WT) were grown to confluence before molecular and functional studies. High-stringency Northern blot hybridization, utilizing specific cDNA probes, confirmed that NKCC1 was expressed in both cell lines and its mRNA levels were twofold higher in CFPAC-WT cells than in CFPAC-1 cells (P < 0.01, n = 3). Na(+)-K(+)-2Cl(-) cotransporter activity, assayed as the bumetanide-sensitive, Na(+)- and Cl(-)-dependent NH(+)(4) entry into the cell (with NH(+)(4) acting as a substitute for K(+)), increased by approximately 115% in CFPAC-WT cells compared with CFPAC-1 cells (P < 0.01, n = 6). Reducing the intracellular Cl(-) by incubating the cells in a Cl(-)-free medium increased Na(+)-K(+)-2Cl(-) cotransporter activity by twofold (P < 0.01, n = 4) only in CFPAC-WT cells. We concluded that NKCC1 is expressed in pancreatic duct cells and mediates the entry of Cl(-). NKCC1 activity is enhanced in the presence of an inward Cl(-) gradient. The results further indicate that the presence of functional CFTR enhances the expression of NKCC1. We speculate that CFTR regulates this process in a Cl(-)-dependent manner.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Biological Transport / drug effects
  • Biological Transport / physiology
  • Carrier Proteins / genetics*
  • Cells, Cultured
  • Chlorides / pharmacokinetics
  • Colforsin / pharmacology
  • Cystic Fibrosis / metabolism
  • Cystic Fibrosis Transmembrane Conductance Regulator / metabolism*
  • Gene Expression / physiology
  • Humans
  • Pancreatic Ducts / chemistry
  • Pancreatic Ducts / cytology*
  • Quaternary Ammonium Compounds / pharmacokinetics
  • RNA, Messenger / analysis
  • Sodium / pharmacokinetics
  • Sodium Bicarbonate / metabolism
  • Sodium-Potassium-Chloride Symporters

Substances

  • CFTR protein, human
  • Carrier Proteins
  • Chlorides
  • Quaternary Ammonium Compounds
  • RNA, Messenger
  • Sodium-Potassium-Chloride Symporters
  • Cystic Fibrosis Transmembrane Conductance Regulator
  • Colforsin
  • Sodium Bicarbonate
  • Sodium