The cystic fibrosis (CF) gene encodes a cAMP-regulated chloride channel, the CF transmembrane conductance regulator (CFTR). CFTR inhibitor II, also known as GlyH-101, is a glycine hydrazide that selectively and reversibly blocks the CFTR channel (Ki = 4.3 μM). This compound binds to a site at the external pore of CFTR, occluding the pore and rapidly preventing chloride transport. Intraluminal CFTR inhibitor II greatly reduces intestinal fluid secretion induced by cholera toxin. It is effective in cells in culture and also in nasal and intestinal epithelia in vivo.
