Author's email address D. N. Sheppard: D.N. Sheppard@ed.ac.uk
Mechanism of Glibenclamide Inhibition of Cystic Fibrosis Transmembrane Conductance Regulator Cl− Channels Expressed in a Murine Cell Line
Article first published online: 30 SEP 2004
The Journal of Physiology
Volume 503, Issue 2, pages 333–346, September 1997
How to Cite
Sheppard, D. N. and Robinson, K. A. (1997), Mechanism of Glibenclamide Inhibition of Cystic Fibrosis Transmembrane Conductance Regulator Cl− Channels Expressed in a Murine Cell Line. The Journal of Physiology, 503: 333–346. doi: 10.1111/j.1469-7793.1997.333bh.x
- Issue published online: 30 SEP 2004
- Article first published online: 30 SEP 2004
- Received 04 March 1997; accepted 27 May 1997.
- 1The sulphonylurea drug glibenclamide is a widely used inhibitor of the cystic fibrosis transmembrane conductance regulator (CFTR). To investigate how glibenclamide inhibits CFTR, we studied CFTR Cl− channels using excised inside-out membrane patches from cells expressing wild-type human CFTR.
- 2Addition of glibenclamide (10–100 μM) to the intracellular solution caused a concentration-dependent decrease in the open time of CFTR Cl− channels, but closed times did not change. This suggests that glibenclamide is an open-channel blocker of CFTR.
- 3Glibenclamide is a weak organic acid. Acidification of the intracellular solution relieved glibenclamide inhibition of CFTR, suggesting that the anionic form of glibenclamide inhibits CFTR.
- 4To begin to identify the glibenclamide binding site in CFTR, we investigated whether glibenclamide competes with either MgATP or Cl− ions for a common binding site. Glibenclamide inhibition of CFTR was unaffected by nucleotide-dependent stimulation of CFTR, suggesting that glibenclamide and intracellular MgATP interact with CFTR at distinct sites.
- 5Glibenclamide inhibition of CFTR was voltage dependent and enhanced when the external Cl− concentration was decreased. The data suggest that glibenclamide and Cl− ions may compete for a common binding site located within a large intracellular vestibule that is part of the CFTR pore.