Received for publication October 1, 2007.
Revised February 12, 2008.
Accepted for publication February 12, 2008.

-AMINOAZAHETEROCYCLIC-METHYLGLYOXAL ADDUCTS DO NOT INHIBIT CFTR CHLORIDE CHANNEL ACTIVITY

Abstract

Inhibitors of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel have potential applications in the therapy of secretory diarrheas and polycystic kidney disease. Recently, several highly polar -aminoazaheterocyclic-methylglyoxal adducts were reported to reversibly inhibit CFTR chloride channel activity with IC50 values in the low picomolar range (Routaboul et al. J. Pharmacol. Exp. Ther. 322:1023-1035), more than 10,000-fold better than that of thiazolidionone and glycine hydrazide CFTR inhibitors identified previously by high-throughout screening. Here, we resynthesized and evaluated the -aminoazaheterocyclic-methylglyoxal adducts of Routaboul et al. reported to have high CFTR inhibition potency (compounds 5, 7 and 8). We verified that the reported synthesis procedures produced the target compounds in high yield. However, we found that these compounds did not inhibit CFTR chloride channel function in multiple cell lines at up to 100 µM concentration, using three independent assays of CFTR function including short-circuit current analysis, whole-cell patch-clamp and YFP-fluorescence quenching. As positive controls, near 100% CFTR inhibition was found by thiazolidionone and glycine hydrazide CFTR inhibitors. Our data provide direct evidence against CFTR inhibition by -aminoazaheterocyclic-methylglyoxal adducts.

Key words: CFTR, Electrophysiology, Patch-clamp, cholera, cystic fibrosis, diarrhea