Influence of ipratropium bromide on nasal trans-epithelial potential difference

Ipratropium bromide (113) is often used as a mild bronchodilator to treat bronchial hyperresponsivenes. Aim of the study was to examine the effect of IB on alternative and CFTR-dependent chloride channels in the apical membrane of respiratory epithelia using measurement of nasal transepithelial potential difference. Nasal transepithelial potential difference (NPD) was determined below concha nasalis inferior in 19 healthy subjects (16-47 years) and 9 CF patients (17-39 years). Blocking apical sodium channels, nasal mucosa was sequentially superfused with (1) chloride buffer, (2) chloride-free solution and (3) salbutamol or 113 (in chloride-free buffer). In 22 healthy subjects, during blockage of apical sodium channels, IB increased nasal transepithelial potential difference by 17,2 +/- 7,3 mV (mean +/- SD, 92,3 +/- 61,8%). The effect of salbutamol was not significantly different (17,8 +/- 6,5mV; 97,0 +/- 27,7%). There was no increase of NPD by IB nor by salbutamol (-11,44mV; -5,6% vs. -14,8mV; -6,8%) in 9 CF-patients. The effect of 113 on NPD during blockage of apical sodium channels suggests a specific effect of IB on MR-function in healthy subjects.