Example of nasal potential difference tracing (NPD) (a, b) and CFTR immunostaining with MATG 1061 monoclonal antibody of nasal ciliated cells (c,d) before (a,c) and after (b,d) parenteral gentamicin treatment in a Y122X homozygous CF patient. In (d), insert of nasal epithelial cells from a healthy control subject. Scale bars are 40, 20 and 60 microns for (c), (d) and insert, respectively. (a) NPD before treatment showed a basal NPD of -50 mV, strong depolarisation in response to 100 μM amiloride (25 mV), and no significant response to CFTR activation by 10 μM isoproterenol in chloride-free solution. (b) At the end of treatment, basal PD was close to -45 mV, amiloride-induced depolarisation had not changed, and addition of isoproterenol in chloride-free solution induced hyperpolarisation of ~ -5 mV, indicating a CFTR-dependent chloride transport. (c) No CFTR labeling was observed before treatment. (d) After gentamicin treatment, CFTR labeling was detected in the patient's nasal cells.