[Status of determining the transepithelial potential difference (PD) of the respiratory epithelium in the diagnosis of mucoviscidosis].

Patients with cystic fibrosis (CF) have an increased transepithelial electrical potential difference (PD) on the respiratory mucosa. In an attempt to investigate the diagnostic value of this measurement 12 patients with CF, 15 first degree relatives and 38 controls were studied. A nasal recording electrode and a reference electrode placed subcutaneously in the left upper arm were used. The recorded values of nasal PD were significantly (p less than 0.0001) higher (-61 mV +/- 7) than in subjects without cystic fibrosis (-21 mV +/- 6) and in CF relatives (-25 mV +/- 8). There was an overlap in values measured on the lip and on the tongue of subjects with and without cystic fibrosis. No differences in nasal PD were noted between male or female subjects. Transepithelial potential difference declined slightly with age. In addition, a superfusion with amiloride as inhibitor of sodium transport induced a 62% reduction in nasal PD in a cystic fibrosis patient as compared to a healthy subject (31%). These results as well as the good reproducibility (r = 0.99) demonstrate that the measurement of transepithelial potential difference on the nasal mucosa could be an additional diagnostic tool in cystic fibrosis.