The goal is to understand how a defective ion channel leads to the human genetic disease cystic fibrosis. Studies of ion channels and ion transport involved in gland fluid transport. Methods include SSCP mutation detection and DNA sequencing, protein analysis, patch-clamp recording, ion-selective microelectrodes, electrophysiological analyses of transmembrane ion flows, isotopic methods, DIC (Nomarkski) and fluorescence microscopy, optical methods for analysis of fluid secretion by cultured human cells and from intact human tissues obtained after surgery.