CFTR and cystic fibrosis: We tested this possibility by comparing the Fsk responses with PIVCFTR-corrected CF HAE (>100-fold increased CFTR) to non-CF HAE (endogenous CFTR levels) with protocols designed to make the electrochemical driving force for Cl− secretion nonlimiting (bathing solutions changed from Cl− replete [Krebs bicarbonate Ringer, KBR] to Cl− deplete [high potassium low chloride, HKLC]).